World Agriculture 1612 1616 September 2016

editors

World Agriculture Editorial Board Patrons Professor Yang Bangjie Member of the Standing Committee of the National People’s Congress of China.

(China) Lord Cameron of Dillington Chair of the UK All Party Parliamentary Group for Agriculture and Food for Development. (UK) Maxwell D. Epstein Dean Emeritus, International Students and Scholars, University of California, Los Angeles. (USA) Sir Crispin Tickell GCMG, KCVO, formerly, British Ambassador to the United Nations and the UK’s Permanent Representative on the UN Security Council (UK) Managing Editor and Deputy Chairman Dr David Frape BSc, PhD, PG Dip Agric, CBiol, FRSB, FRCPath, RNutr Mammalian physiologist Regional Editors in Chief Robert Cook BSc, CBiol, FSB. (UK) Plant pathologist and agronomist Professor Zhu Ming BS, PhD (China) President of CSAE & President of CAAE Scientist & MOA Consultant for Processing of Agricultural Products & Agricultural Engineering, Chinese Academy of Agricultural Engineering Deputy Editors Dr Ben Aldiss BSc, PhD, CBiol, MSB, FRES. (UK) Ecologist, entomologist and educationalist Dr Sara Boettiger B.A. ,M.A.,Ph.D (USA) Agricultural economist Professor Neil C. Turner FTSE, FAIAST, FNAAS (India), BSc, PhD, DSc, (Australia) Crop physiologist Professor Xiuju Wei BS, MS, PhD (China) Executive Associate Editor in Chief of TCSAE, Soil, irrigation & land rehabilitation engineer

Published by Script Media, 47 Church Street, Barnsley, South Yorkshire S70 2AS, UK

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Members of the Editorial Board Professor Gehan Amaratunga BSc, PhD, FREng, FRSA, FIET, CEng. (UK & Sri Lanka) Electronic engineer & nanotechnologist Professor Pramod Kumar Aggarwal B.Sc, M.Sc, Ph.D. (India), Ph.D. (Netherlands), FNAAS (India), FNASc (India) Crop ecologist Dr Andrew G. D. Bean BSc, PhD, PG Dip. Immunol. (Australia) Veterinary pathologist and immunologist Professor Tim Benton BA, PhD, FRSB, FLS Food systems, food security, agriculture-environment interactions Professor Phil Brookes BSc, PhD, DSc. (UK) Soil microbial ecologist Professor Andrew Challinor BSc, PhD. (UK) Agricultural meteorologist Dr Pete Falloon BSc, MSc, PhD (UK) Climate impacts scientist Professor Peter Gregory BSc, PhD, CBiol, FSB, FRASE. (UK)

Soil scientist Professor J. Perry Gustafson BSc, MS, PhD (USA) Plant geneticist Herb Hammond (Canada) Ecologist, forester and educator Professor Sir Brian Heap CBE, BSc, MA, PhD, ScD, FSB, FRSC, FRAgS, FRS (UK) Animal physiologist Professor Fengmin Li BSc, MSc, PhD, (China) Agroecologist Professor Glen M. MacDonald BA, MSc, PhD (USA) Geographer Professor Sir John Marsh CBE, MA, PG Dip Ag Econ, CBiol, FSB, FRASE, FRAgS (UK) Agricultural economist Professor Ian McConnell BVMS, MRVS, MA, PhD, FRCPath, FRSE. (UK) Animal immunologist Hamad Abdulla Mohammed Al Mehyas B.Sc., M.Sc. (UAE) Forensic Geneticist Professor Denis J Murphy BA, DPhil. (UK) Crop biotechnologist Dr Christie Peacock CBE, BSc, PhD, FRSA, FRAgS, Hon. DSc, FSB (UK & Kenya) Tropical Agriculturalist Professor R.H. Richards C.B.E., M.A., Vet. M.B., Ph.D., C.Biol., F.S.B., F.R.S.M., M.R.C.V.S., F.R.Ag.S. (UK) Aquaculturalist Professor Jacqueline Rowarth PhD, CNZM, CRSNZ, FNZIAHS (New Zealand) Agricultural Economist Professor John Snape BSc PhD (UK) Crop geneticist Professor Om Parkash Toky MSc, PhD, FNAAS, (India) Forest Ecologist, Agroforester and Silviculturist Professor Mei Xurong BS, PhD Director of Scientific Department, CAAS (China) Meteorological scientist Professor Changrong Yan BS, PhD (China) Ecological scientist Advisor to the board Dr John Bingham CBE, FRS, FRASE, ScD (UK) Crop geneticist Editorial Assistants Dr. Zhao Aiqin PhD (China) Soil scientist Ms Sofie Aldiss BSc (UK) Rob Coleman BSc MSc (UK) Michael J.C. Crouch BSc, MSc (Res) (UK) Kath Halsall BSc (UK) Dr Wang Liu BS, PhD (China) Horiculuturalist Dr Philip Taylor BSc, MSc, PhD (UK)

In this Issue ...

Fourth issue contents

editorials: Number 1612 n In this Issue – The part played

by World Agriculture in three vital roles of countryside on the Earth Dr David Frape

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scientific: Number 1613 n Innovative agroforestry for 51-58 environmental security in India.

S.B. Chavan, Professor O.P.Toky, Dr. A.K. Handa, A.R. Uthappa, Dr. Ram Newaj and Dr S.K. Dhyani Number 1614 n The functions and sizes of 59-64 the five carbon sinks on planet Earth and their relation to climate change.

Part I – Their present sizes and locations.

Dr David Frape

If you wish to submit an article for consideration by the Editorial Board for inclusion in a section of World Agriculture: a) Scientific b) Economic & Social c) Opinion & Comment or d) a Letter to the Editor please follow the Instructions to Contributors on the website and submit by email to the Editor editor@world-agriculture.net Published by Script Media, 47 Church Street, Barnsley, South Yorkshire S70 2AS, UK

book review and economics & social: Number 1615 n A review of Dame Fiona 65-66 Reynolds’ book: The Fight for Beauty, Publ. Oneworld Publications, London 2016; and on the effects of land use on climate change.

Dr David Frape Number 1616 n Some notes on the politics of survival.

Professor Sir John Marsh

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In this Issue – The part played

by World Agriculture in three vital roles of countryside on the Earth

his Issue is one of the more important Issues of World Agriculture.

The pages here are more numerous than is normally the case. We deal with one of our fundamental purposes and objectives.

This is to give a clear, description of the some of the complex, vital problems confronting this World and where possible propose solutions.

Policy makers carry out their duties in response to pressure from the voting public.

It is up to that public with the very best and well-informed motives to apply the pressure for solutions to issues which are for the long term sustainable benefits of the whole world.

Unfortunately this should not involve many of the current, widely publicised, pressure groups, which frequently have sectional interests at heart, or are composed of ill-informed individuals.

It is for scientists, economists and sociologists, who normally discourse amongst themselves, to make clear statements ‘for the man in the street’ what urgent and grave issues need action.

The most important issue, bar none at the present time, is climate change, and unless the world acts quickly we conclude the situation could be catastrophic.

Unfortunately, the required action will undoubtedly have an adverse effect on

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the standard of living of many at present and so would be difficult for policy makers to invoke and institute. But that is the nature of the beast!

In the first paper we describe the many purposes of agroforestry. This is

by Chavan et al. which demonstrates the multi-functional role played by agroforestry in the landscape. These include a range of “environmental services such as those of provisioning services (food, fuel, fibre, fresh water and genetic resources), regulating services (climate regulation, water maintenance and erosion control), cultural services (spiritual enrichment, reflection, recreation and aesthetic values) and those of supporting services (production of oxygen and soil formation).”

We then consider the activity of forestry in carbon sequestration as part of the carbon cycle of Nature.

Subsequently, we discuss a recently published book, which shows the conflict in the mind of the general public between the countryside which has three roles: it has an essential aesthetic role, it has an essential food producing job and it has its most important role as part of the carbon cycle.

This is vital, because without fulfilling that role the other two would fail. We conclude that a greatly increased world forestry expanse alone will not, by itself, solve the problem of the high rate of greenhouse gas (GHG) emissions. It

will require urgent and difficult political action to rectify this situation.

The final short trenchant note by Professor Sir John Marsh makes clear the indispensable part played by the political leader.

“This is a leadership challenge missing from a political system that is professionally neutral about religion. It delivers power to those who guess what the voters would like to hear and reflect that to them as policy intention. It is wholly irresponsible about the impact of such populist policies upon the real welfare of society.”

“It is the nature of research that those who participate develop their own language and their own view of the world.

“Confronted by problems each group seeks and sometimes identifies solutions within that framework.

“This note argues that because global warming affects all the elements that underpin the lifestyles we seek and enjoy we need a shared responsibility that includes natural sciences, socioeconomic analysis, political and religious conversation and communicators at all levels.

“Parallel debates among experts are not enough. It has to involve the whole community in ways that offer not just a continuation of current consumption patterns but a lifestyle that is more rewarding and sustainable.”

David Frape

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Innovative agroforestry for environmental security in India

S.B. Chavan1, Prof O.P.Toky2, Dr. A.K. Handa3, A.R. Uthappa1, Dr. Ram Newaj4 and Dr S.K. Dhyani5 Scientist (Forestry)1, Principal Scientist (Forestry)3 & Principal Scientist (Agronomy)4 ICAR-Central Agroforestry Research Institute, Jhansi, India 2Ex-ICAR Emeritus Scientist, CSS Haryana Agricultural University, Hisar, India 5Principal Scientist (Agroforestry), Natural Resource Management Division, ICAR, New Delhi, India Dr. O. P.Toky Ex ICAR Emeritus Scientist, Ex Dean, Postgraduate Studies CCS Haryana Agricultural University, Hisar-125004 (India) Mobile: ++91 9896173626 E-mail: optoky@gmail.com

Summary

Agroforestry is emerging as an important land use system for integrated natural resource management and for addressing wide range of issues such as soil degradation, biodiversity conservation and climate change. Apart from a profit oriented approach and technology, it is the need of the hour to focus on ecosystem services in agroforestry. Present and past evidence indicates that agroforestry results in a multi-functional landscape providing different environmental services such as provisioning services (food, fuel, fibre, fresh water and genetic resources), regulating services (climate regulation, water maintenance and erosion control), cultural services (spiritual enrichment, reflection, recreation and aesthetic values) and supporting services (production of oxygen and soil formation). Natural resource management through agroforestry is an essential part of its evolution and wide adoption in the India. This paper highlights the various services rendered by agroforestry viz, soil-based, biodiversity conservation, improvement of problematic soils and carbon sequestration.

Key words: Ecosystem services, agroforestry, biodiversity conservation, carbon sequestration and shifting cultivation Glossary: Biochar is the solid material obtained from thermo-chemical conversion of biomass in an oxygen-limited environment.

Biomass, the organic matter derived from living and dead organisms, dried at 60 C. For trees, shrubs, herbs and the litter it is the organic matter by weight per unit area.

Micro-climate is a local set of atmospheric conditions that differ from those of surrounding area.

Salinisation is the accumulation of soluble salts of sodium, magnesium and calcium in soil to the extent that soil fertility is severely reduced. Also it characterized by an electrical conductivity (EC) of typically more than 15 dS/m, deci Siemens per meter. A salty solution contains charged particles which conduct electricity. If salt sensitive crops are being grown the conductivity should be is less than about 700 µS/cm (i.e. 70 dS/m).

Multipurpose tree is the tree species that are deliberately grown and managed for more than one output. They provide multiple tree products like timber, fodder, fruits, fuel wood, gum, resins, fibre, etc.

Shifting cultivation is also known as slash-and-burn cultivation where farmers slashes out ground vegetation by axe and burns it to clear land for agriculture purposes.

Allelopathy is a process by which plants release chemical compounds into their environment to keep other competitive vegetation in check.

Riparian area is the interface between land and a river or stream.

Abbreviations: UNFCCC: United National Framework Convention on Climate Change BNF: Biological Nitrogen Fixation SOC: Soil Organic Carbon MBC: Microbial Biomass Carbon EC: Electrical conductivity FAO: Food and Agricultural Organization of United Nations AICRP-AF: All India Co-ordinated Research Programm on Agroforestry

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Introduction

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he role of trees in environmental security has been well known for ages.

Trees in agroforestry systems not only provide direct benefits (food, fodder, fuelwood, fertilizers, fibres, etc) but also improve soil fertility, reduce soil erosion, filter atmospheric pollutants and most importantly they maintain carbon balance.

Growing multipurpose trees along with agricultural crops, has been considered as a panacea for maladies of intensive agriculture and deforestation.

It is considered to be one of the key paths towards prosperity of small and marginal farmers facing the challenges of low and uncertain yields, deterioration of the soil and environmental resources and suffering from hunger, malnutrition and poverty particularly in areas that have been bypassed by the green revolution (1).

Agroforestry helps coping with climate change by storing carbon, trees buffers weather-related production losses, enhancing resilience in climate impacts and trees can provide income and a diversity of food sources through treebased products (2).

Farmers believe agroforestry is a boon particularly during drought when rainfed crops fail and trees provide fodder, fruit, vegetable, fuelwood, timber and fibre for sustaining rural livelihood.

The respected Nobel Prize Laureate, Wangari Maathai at a second World Agroforestry Congress, said: “Trees have an important role to play, not only in climate change mitigation, but also in reducing vulnerability to climate-related risks.”

The potential capacity of Agroforestry to adapt to harsh climatic events is greater

Fig 2. Agroforestry for soil conservation

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Fig 1. Multi-functional agroforestry systems sustainability has been well documented than is agriculture because it is playing (Fig 2). an important role in ecosystems services, Its systems are likely to be more by preventing land degradation, coping effective in erosion control through with various vagaries of climate. It has been stated that agroforestry systems are supply of litter to the ground surface than through the effects of the tree canopy (3). treasures of ecosystem services which It is the source of organic matter by could act as a symbol of nine planetary litter fall, debris and nitrogen fixation boundaries of world. which can maintain the fertility of soil.

The multi-functional role of agroforestry Erosion is regarded as one of a number (Fig 1) has been emphasized by both of forms of soil degradation, including the the Millennium Ecosystem Assessment deterioration of physical, chemical and and the International Assessment of biological properties, all of which require Agricultural Science and Technology for attention.

Development.

Agroforestry provides soil based ecosystem services from numerous Agroforestry for soil based services positive interactions (1).

Agroforestry practices play an important A major contribution of its trees to soil role in improving the fertility of the soils. based ecosystem services occurs as a Its role in enhancing and maintaining result of above-ground and below-ground long-term soil productivity and organic inputs that provide food and nutrients needed for the soil organisms involved in carbon transformations and nutrient cycling (Fig 3).

Biological nitrogen fixation (BNF) constitutes a key nutrient input to agro-ecosystems. The contribution of leguminous trees to building up N in degraded soils through BNF is well recognized as an important component of the ecosystem service of nutrient cycling (1). There are significant differences in estimates of BNF in trees, ranging from high rates up to 472 kg N2 ha−1 year−1 in L. leucocephala, Gliricidia sepium, and Calliandra calothyrsus to low rates <50 kg N2 ha−1 yr−1 in Acacia melanoxylon and A. holoserica (4), whereas roots of Casuarina species fix nitrogen at up to 350 kg N ha−1 yr−1.

There are two types of the nitrogen fixation, symbiotic and asymbiotic nitrogen fixation. The symbiotic nitrogen fixed by actinomycttes fungi and nodule forming rhizobium species.

In asymbiotic nitrogen fixation, the free living organisms of soil like clostridium (anaerobic), azotobactor (aerobic), Blue green algae (cynobacteria) and

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Fig 3. Soil based ecosystem services in agroforestry (AF) some lichen fixes of free nitrogen of the soil by all the microorganism living freely or outside the plant cell.

Ecosystem services offered by agroforestry Trees in agroforestry are offering several services by directs and indirect means.

The followings are the positive interactions (Adapted from Luedeling et al.16 & Atangona et al.17): n Trees can act as a safety net by capturing nutrients leached from the topsoil, and they can return these to the soil surface as litter (18). n Trees add litter on soil surface layer and its impact increases the activity of soil biota and reduces exposure of the soil surface. This can improve water infiltration into the soil and reduce surface runoff (19) n Trees in agroforestry help to reduce evaporative demand of crops per unit of photosynthesis by lowering windspeeds and the higher humidity under trees partially compensates increased water use (20). n Turnover of fine roots contributes considerable amounts of soil carbon which acts as a major source of soil organic matter in situations where aboveground organic inputs decompose in a surface litter layer (21).

n Nitrogen fixing trees (NFT) can substantially improve the balance and availability of N in agro-ecosystems by adding the nitrogen at the rate of 43-581 kg N ha-1year-1 (Table 1) n Trees can also trap dust and sediment as well as being sites for nutrient accumulation from animals (including birds) that perch on them or seek shelter in their shade, where they urinate or defecate, is a nitrogenous waste in solid form (22). n Agroforestry may improve water use efficiency by reducing the unproductive components of the water balance, such as run-off, soil evaporation and drainage (23). n Trees in agroforestry systems capture water resources mainly from deep soil layers beyond the reach of annual crops. Crop roots in drier surface soil may benefit from hydraulic lift of water by trees from wetter soil at depth (24) n Microclimate modification by trees also provides ecosystem services, e.g. shade and temperature under tree canopies can be substantially lower than in an open field, potentially reducing heat stress for plants and animals particularly during the hottest hours of the day. n Reductions in wind speed are directly beneficial to crops, as they

Table 1. Biological nitrogen fixing trees and shrubs in agroforestry systems

reduce the mechanical damage to crops, such as leaf tearing and crop lodging (25). n Insectivorous birds and beneficial insects hosted by trees have been shown to regulate insect pest populations and pollinate crops (26). n Multispecies systems can sequester carbon over pure crop stands.

Trees and crops (27, 28) may also enhance the soil carbon content, thus participating in climate change mitigation. Rain interception by trees reduces the soil erosion and allows conservation of soil and water. n The effect of agroforestry on weed suppression is also well documented (9). Mixing tree species may also reduce the specific diversity of the weed stand and lead to a change in biomass distribution between weed species n Some of the toxic substance secretions i.e. allelopathy may be useful in control of weeds, insect nematodes and disease pathogens (30).

Agroforestry for biodiversity conservation The concept of agroforestry embraces many intermediate intensity land use forms, where trees still cover a significant proportion of the landscape and influence microclimate, matter and energy cycles and biotic processes (31).

The protection of natural habitats remain the backbone of biodiversity conservation strategies, promoting agroforestry on agricultural land especially in arid and semi arid areas where natural habitat has been highly fragmented.

According to FAO (32), agroforestry improves above ground biodiversity as it provides more habitats and food for birds, small mammals, reptiles, earthworms, insects, etc., which in turn lead to an increase in species diversity and population.

Agroforestry helps in reducing biodiversity loss by providing a protective tree cover along agricultural fields and by providing habitat for a diversity of flora and fauna.

It helps in conserving genetic diversity of ethnocultivars or landraces and for trees that are in danger of loss and require priority conservation (33). Altieri (34) opined that since AFS are more diverse and have lowinput strategies, these have greater biological interactions and thus are richer in biodiversity.

Agroforestry can (1) provide secondary habitats for species, (2) reduce the rate of conversion of natural habitats, and (3) create a benign and permeable matrix (corridor) between habitat (5) and conservation of biological diversity by providing other ecosystem services such as erosion control and water recharge,

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thereby preventing the degradation and loss of surrounding habitats (31, 35).

Table 2 represents the design and development peculiar to agroforestry systems for biodiversity as well as for commerce.

Agroforestry for problematic soils Agroforestry has high potential for simultaneously satisfying three important objectives viz., protecting and conserving natural resources; producing a high level of output of economic goods; and improving income and raw materials for rural populations (1).

The studies indicated that under agroforestry systems soil organic carbon and available nutrients increased as compared to growing only trees or a sole agricultural crop.

Experimental evidence under an agrisilvihorticultural system (aonla+ leucaena + blackgram)in rainfed conditions showed that after nine years organic carbon was increased by 65 to 109.4% under closed canopy conditions and by 28.1 to 62.5% under open canopy as compared to initial value (0.32%). The tree are performing prominent role in enhancing soil organic carbon.

The organic carbon per cent under the canopy of aonla is higher than open canopy owing to the fall of aonla leaves, being mostly restricted to the tree canopy (37). An increase in organic carbon, and available N, P and K content in a Khejri (Prosopis cineraria) based silvipastoral system compared with no-Khejri soil, indicates retention/plantation of Khejri trees on pasture land. The Khejri based system has led to higher fodder production to meet the needs for food, fodder, fuel and small timber (38, 39).

An increase in soil organic carbon status of surface soil has been observed: 0.39% to 0.52% under Acacia nilotica + Sachharum munja and 0.44% to 0.55% under Acacia nilotica + Eulaliopsis binata after five years. There are indications that Acacia nilotica a tree + Eulaliopsis binata a grass are conservative, more productive and less competitive and are suitable for eco-friendly conservation and rehabilitation of degraded lands of Shivalik foot hills of subtropical northern India (40).

Table 3 shows the soil health status under a Prosopis cineraria-based agroforestry as compared to sole or open field. The studies of an agri-silvicultural system growing of Albizia procera with different pruning regimes, showed that the organic carbon of the soil increased by 13-16% from their initial values which was five to six times higher than growing of either sole tree or a sole crop (41).

Evaluation of soil chemical properties in a traditional agroforestry system of the north-eastern region indicates a spectacular increase in soil pH, organic-C, exchangeable Ca, Mg, K, and build up of avai1able P under different agroforestry practices within 10-15 years

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Table 2. Desirable characteristics of agroforestry systems for biodiversity conservation (adapted from Harvey et al. 36) with erosion control structures, such (42). Similar results have been shown as half moon terraces, contour bunds, when MPTs (Multipurpose trees and grassed waterways, gully plugging and shrubs) were evaluated in an extremely bench terracing are helpful from water P-deficient acid Alfisol in Meghalaya. conservation and production points of MPTS, including Alnus nepalensis, view.

Parkia roxburghii, Michelia oblonga, Pinus The overall (biomass) productivity, soil kesiya, and Gmelina arborea led to: a) fertility improvement, soil conservation, greater surface cover (43), b) a constant nutrient cycling, microclimate leaf litter fall and extensive root systems improvement, and carbon sequestration with a 96.2% increase in soil organic potential of an agroforestry system are carbon, c) a 24.0% increase in aggregate generally greater than that of an annual stability, d) an increase of 33.2% in system (45). available soil moisture and e) a reduction Further, alley cropping i.e. intercropping of 39.5% in soil erosion. in interspaces of hedgerows, is a proven Soils under Acacia auriculiformis, and sustainable agroforestry technology Leucaena leucocephala and Gmelina for resource conservation and sustainable arborea have a persistently high production. Fertiliser Trees are used humification rate while soils under the in agroforestry to improve the soil canopy of Michelia champaca, Tectona condition by adding nutrient by nitrogen grandis and Dalbergia sissoo show low fixation and leaf shading e.g. Indigofera, humification of the organic matter (44).

Leucaena, Sesbania, and Albizia have Such improvements in soil quality been tested as alley or hedgerow crops. under agroforestry systems have a direct Alley cropping with Leucaena bearing on long-term sustainability and leucocephala was effective for erosion productivity of soils,being a viable option control on land sloping up to 30%. The for eco-restoration, maintenance of contour-paired rows of Leucaena hedge, soil resources for obtaining ecosystem Leucaena and Eucalyptus trees, and 0.75 services, as good air and water quality in m wide grass barrier at 1.0 m interval in the area. maize reduced runoff of rainfall from 40% Association of MPTS with arable to 30% and soil loss from 21t to 8t ha-1 crops in arable lands and development on 4% sloping land (46). of agroforestry systems such as agriMultipurpose trees and shrubs (MPTs) silviculture, agri-horticulture, silvican be used on sodic soils where annual pasture and horti-pastoral systems crops cannot be grown due to higher pH on all kinds of degraded wastelands and EC. Trees, through their roots, open have been examined. The results the compact subsoil and improve indicate agroforestry interventions

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Table 3. Recommended tree species for problem soils in India water permeability and thus facilitate salt leaching.

By the planting of MPTS, soil pH and EC was decreased to 8.2 and 0.2 mmhos/cm from initial values of 10.5 and 0.736 mmhos/cm, respectively, after 11 years recording. The soil organic carbon, available P and K were increased. Among the tree species tested, Acacia nilotica, Albizia procera, Leucaena leucocephala, Azadirachta indica and Eucalyptus hybrids were found to be the most suitable tree species for rehabilitation of sodic soils and to maintain an eco-friendly systems (47).

Agroforestry has played a major role in the rehabilitation of wastelands, desert and lands degraded by salinisation, water and wind erosion (1). The replacement of field crops and horticulture by silvipasture and agroforestry for, the productive and protective purposes has led to a reduction in runoff in watershed management of 48 to 99% and reduction in soil loss 81 to 98%.

There is the added benefit of a reduction in the rate of population migration from 26.6% before the implementation of Watershed Management to 9.3% during the project period (48). Table 2 exemplifies how different agroforestry tree species suitable for different problem soils can ameliorate the soil condition.

Agroforestry for carbon sequestration The United Nations Framework

Convention on Climate Change (UNFCCC) defines carbon sequestration as the process of removing C from the atmosphere and depositing it in a reservoir (wood or soil).

It entails the transfer of atmospheric CO2, and its secure storage in longlived pools (49).The carbon cycle in plants is driven by the process of photosynthesis (Fig 4). The agroforestry systems have the potential to sequester large amounts

of above and below ground carbon compared to treeless farming systems (50, 51). The agroforestry is well recognised by scientific community for their role in climate change adaptation and mitigation due to its multiple plant species (52).

In India, evidence is now emerging that agroforestry systems are promising land use to increase and conserve aboveground and soil carbon stocks to mitigate climate change (53). Average sequestration potential in agroforestry in India has been estimated to be 25 t C ha-1 over 96 million ha (54).

A study conducted under AICRP-AF shows that in subtropical sub-montane low hill areas agroforestry can enhance carbon sequestration by 50 per cent for both arable and non-arable lands.

A study conducted on the potential of carbon dioxide sequestration of existing green belt at JSW Steel limited in Bellary district of Karnataka found that tree plantations and agroforestry have a huge potential in sequestrating the carbon produced by such heavy industries (55).

Table 3 shows the potential of carbon sequestration by various agroforestry systems in India adapted from Chavan et al. (56).

Shifting agriculture

Biomass As reported by North Eastern Council, Shillong, Meghalaya, about 1.46 Mha is affected by shifting cultivation in the north-eastern region.

In India, about 2.32 M ha is under shifting cultivation in states other than the north-eastern region and about 2.53 million families are engaged in this practice.

Fig 4. Carbon sequestration process in an agroforestry system (adapted from Ram Newaj et al. 51)

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Biomass is the key component of slash and burn agriculture. The biomass stores and conserves the nutrients and recycles them for replenishment of soil fertility. In the areas of slash and burn agriculture, secondary succession rehabilitates the abandoned fields.

The biomass, net primary productivity and litterfall patterns during a 20-year fallow, subsequent to shifting agriculture were studied at Burnihat in north-eastern India (57). Succession was accompanied by increased species diversity, reduced dominance, and increased above-ground productivity which reached 18t ha-1 yr-1 in a 20-year old fallow. Litterfall increased with the age of the fallow up to 10t ha-1 yr-1 in a 20-year fallow (Table 5).

During the agriculture phase a multistoried crop canopy develops, with perennial crops such as cassava, banana and castor occupying the top layer, cereals constituting the middle layer and cucurbits and legumes forming the lower stratum.

In one of the studies at Burnihat, in north-eastern India (58), the total biomass (root and shoot) obtained from grain and seed yielding crops under a 30-year cycle was 2.5- and 20- times greater than under 10 and 5-year cycles, respectively.

The biomass obtained from leafy and fruit vegetables were maximum under a 5-year cycle, whereas, that from tuberous and rhizomatous crops under the 10-year cycle was almost twice the output of the 5 and 30 year cycles. Maximum economic yield per hectare for rice, maize and Setaria italica (Table 6) was obtained under a 30-year cycle. This yield occurs only once after clearing the fallow of 30 years, meaning that the area of the land would need to be 30 times greater if this cycle was to be operated annually.

In practice, shorter cycles of 5 to 10 years are more common as the population of cultivators has increased in the recent past and available land is scarce.

But the reduction of yield of these crops was 48% and 98% under 10 and 5 years cycles, respectively, c.f. 30 years.

The economic yields of leaf and fruit vegetables, however, were much higher in a short cycle of 5-year than in the longer cycles.

Soil carbon Slash and burn agriculture involves a fallow period from 5 years to sometimes 30 years.

The intensity of burn has significant effects in the properties of soil including organic carbon and pH. Short (slash and burn)cycles of 5 years start with a low budget of carbon as compared to medium and longer cycles (59).

The depletion of soil carbon continues throughout one year of cropping depletes the carbon by up to 22% (Table 7) and further throughout early phases of succession up to 5 years mainly due to a low rate of return of litter (1.2 ton/ha/year) and accelerated oxidation at the surface.

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Table 4. Reported carbon sequestration potential (CSP) (Mg C ha-1yr-1) of various agroforestry systems in India The change in the soil characteristics This is a strong reason for a longer with biochar includes an increase in cycle. The improvement of soil carbon the activity of mycorrhizal fungi and in is maximum for a 10-year fallow due to microbial growth. production of high litterfall (7.1 ton/ha/ Biochar is useful in the acidic tropical year), of which bamboo (Dendrocalamus soils as it raises pH due to its slightly hamiltonii) is the main contributor (53). alkaline nature. If biochar becomes widely This is a good reason for replenishment available for soil improvement, it will of soil fertility over a 10-year fallow – the sequester significant amount of carbon optimum cycle for the yields of cereals that could help counter global warming. and legume compared with a short cycle An increase in soil carbon has a of 5-year in which the yields of rice and significant impact on crop yield. legumes is much reduced.

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Table 5. Biomass of fallows in slash and burn agriculture under short, medium and long (slash and burn) cycles at Burnihat, Meghalaya in northeastern India (Toky and Ramakrishnan, 59).

An increase of one ton of soil carbon would increase crop yield by 20 to 40 kg/ ha of wheat, 10 to 20 kg/ha of maize and 1 kg/ha of cowpeas (60).

Every year the farmer is clearing a new piece of land and shifting to fresh land after one year of cropping.

This cycle is still repeated; whereas now that land is scarce there is need to find alternatives of shifting cultivation.

These we have proposed in this paper.

Recommendations to improve and change shifting agriculture

n Shifting agriculture with a fallow period of more than 10 years is sustainable ecological, economical and energy efficient and it should continue. n Traditional knowledge of cultivation, resource management and plants used should be documented. n Home gardens which are the sites of high species diversity of native trees, shrubs and herbs should be strengthened. n Degraded lands under shorter cycles should be rehabilitated through cash yielding crops such as fruit, spices and short rotation timbers. n Multi-storied agroforestry systems should be developed integrating cash crops such as areca nuts, coconuts, bananas, citrus, and medicinal and aromatic plants. n Nitrogen fixing trees such as alders (Alnus nepalensis) which coppice excellently and could be managed as a single bole, should find place in high

density agroforestry systems. n Bamboo (Dendrocalamus hamiltonii) which is extremely useful and also conserves potassium during the early stage of secondary succession, should be planted in agroforestry systems. n Agroforestry systems could be managed intensively using bio-fertilizers, bio-pesticides and recycling the in-situ produced litter as mulch for nutrient and moisture conservation. n Native stains of useful microbes and fungi should be used for production of bio-fertilizers and bio-fungicides. n The Taungya system should be launched allocating land with plantation crops raised by the Forest Department, as it was extremely successful in the past and still is in several tropical countries. n Fire can be used as a tool to manage the acidic pH of the high rainfall areas. n Involve local people in all research projects and in development of technology. Develop suitable strategies for agricultural marketing and sub­sidies. n Various agencies should coordinate for the benefit of farmers and should improve their buying capacity.

Ways to overcome hurdles of agroforestry adoption n Complexity: the complex nature of agroforestry systems make it difficult to adopt by farmers. To overcome complexity of agroforestry need to restructure and redesigns the systems as per the need of farmers by considering local species. n Competition: this is the main reason of non-adopting agroforestry systems by farmers. The competition among crop

Table 6. Crop diversity and yield (kg/ha/year) in a multi-storey agroforestry farming system under shifting agriculture, compared with rice yield in northeastern India (Toky and Ramakrishnan, 61). n.b. Yield occurs only once after a period of 30 or 10 or 5 years of fallow period. *Percent of d.m. in soil

and trees reduces yield due shade and nutrient availability.

To overcome competition there are numerous practices evolved by scientific community through extensive research on “Tree-Crop Interaction” studies.

The proper tree management practices with suitable tree species can helps to reduce the negative impacts of interaction and increases positive benefits. n Mechanization: In the era of intensive agriculture, tree based systems are one of the hurdles for mechanization.

Therefore the adoption laborious agroforestry systems is very slow or negligible. To overcome this problems, the choice of species and spacing is the key challenge for adopting mechanization. n Policy issues: The tree harvesting and transportation is very difficult due to numerous laws, acts and policies of state forest department.

The tree is subject of forest department and there is no tie-up between forest and agriculture department. As per as India is concern, the government is came up with National Agroforestry Policy 2014 to overcome these issues. n Marketing: The commercial agroforestry is flourished only limited states like Punjab, Haryana, Andhra Pradesh and Tamil Nadu. Rest of states don’t have proper marketing channel and wood based industry, which hinders the agroforestry adoption. n Carbon trading and Ecosystem services: As per the UNFCCC and IPCC, agroforestry is considered as remedies for environmental issues like climate change.

The services provided by trees are not yet quantified properly and paid for that. There is no proper and simple mechanism for payment of ecosystem services (PES).

Conclusion

The World’s environmental agendas are now converging to address the economic, social and environmental dimensions of sustainable development through developing agroforestry.

Agroforestry combines traditional knowledge and more recent research evidence related to optimizing the interaction of trees, crops, livestock, water, soil, social systems and economic systems such as markets and value chains in order to respond sustainably to challenges of economic development and biodiversity.

The services rendered by agroforestry are well documented throughout the world.

Livelihood security and environmental security are prominent services of agroforestry in sustainable agricultural development in which the concepts of resilience and sustainability are followed.

Agroforestry must form part of discussions within the global environmental arena.

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Table 7. Changes in soil organic %* in slash and burn agriculture (jhum) under short, medium and long cycles in north-eastern India (Ramakrishnan and Toky, 62).

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The functions and sizes of the five carbon sinks on planet Earth and their relation to climate change Part I Their present sizes and locations Summary

Dr David Frape

Carbon has been cycled among five spheres of the Earth, the carbon (C) sinks: the biosphere, pedosphere, lithosphere, hydrosphere, and atmosphere over thousands of years. Since the industrial revolution Man has removed C from the lithosphere at a greatly increasing rate (recently at a much greater rate than occurs naturally as a consequence of volcanic and hot-spring activity), a high proportion of which has been combusted, or has been used in cement production. This has greatly increased the proportion of carbon dioxide (CO2), a greenhouse gas (GHG), in the atmosphere. Since 1995, approximately 57% of the carbon released from the fossil fuel source has persisted in the atmosphere, 29% has been transferred to the ocean, and the balance, 15%, has been absorbed by the biosphere. This CO2 concentration has been demonstrated to be closely correlated with climate change and global warming. The purpose of this review is to describe the current sizes and characteristics of the five C sinks. The largest is in the lithosphere estimated to contain 60,000,000 C t x 109. the other four sinks in decreasing order of estimated size, measured as C t x 109, are in the hydrosphere, 38,400; biosphere, 2002, pedosphere, 2000; and atmosphere, 720. The likely causes for the changes in the size of each sink are discussed. The global effects of increasing the temperature of the oceans and soil are discussed, with a climate induced extension of the growing season in the Northern Hemisphere. The warming and drainage of peat bog and fen areas, which now act as a net source of CO2 are of particular concern. Total CO2 emissions from the worldwide 500,000 km2 of degraded peatland may exceed 0.7 Ce t x 109 an.-1. This value is almost 6% of all global carbon emissions. An enhanced uptake rate of C for photosynthesis prompted by the increased concentration of atmospheric CO2 has been countered by deforestation resulting from urban sprawl and increased demand for agricultural production to meet the growing needs for food. In the next Issue the likely quantitative role of agroforestry as a source of environmental services, especially that in C sequestration, will be measured, and estimates will be made of its potential for countering global warming and the consequences on areas then available for crop production. Agroforestry shading might also impact on the current enormous global soil respiration rates which are mainly microbial in origin and are tenfold the annual losses caused by burning fossil fuels and cement manufacture. Solar energy used in heating exposed soil and so stimulating microbial action is used instead for transpiration which requires water to be raised perhaps 20-30 m to the canopy of trees.

Glossary as defined here: Lithosphere: the uppermost layers of the solid Earth, i.e. oceanic and continental crustal rocks and uppermost mantle, which behaves elastically on time scales of thousands of years. It is part of the Geosphere which also includes the inorganic soil, desert sand, mountains and liquid rock in the inner core of the Earth. And includes: Kerogen, a clastic sedimentary rock (shale) within which organic matter is converted into oil and gas.

Pedosphere: The soil, i.e. the sum total of all the organisms, soils, water and air in the soil.

Hydrosphere: the rivers, lakes, streams, oceans, groundwater, polar ice caps, glaciers, aerial moisture and precipitations of rain, hail and snow. The hydrosphere is found on the surface of Earth, but also extends down several miles below, as well as several miles up into the atmosphere.

Biosphere: the total of living and dead organisms (including derived dead organic matter, such as litter, soil organic matter and oceanic detritus). It is the global ecological system integrating all living beings, their relationships, and their interaction with the lithosphere, hydrosphere, and atmosphere. It includes Biomass: The total mass of living organisms in a given area or volume; recently dead plant material is often included as dead biomass.

Atmosphere: includes the troposphere, stratosphere, mesosphere, ionosphere, thermosphere and the extremely thin exosphere. It is the gaseous envelope surrounding the earth.

Aerenchymous shunt: refers to the vessel-like transport tubes within certain plant tissues. Plants with arenchyma possess porous tissue that allows for direct travel of gases to and from the plant roots. Methane can travel directly up from the soil into the atmosphere using this transport system. The direct “shunt” created by the aerenchyma allows for methane to bypass oxidation by oxygen that is also transported by the plants to their roots.

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Introduction

T

he carbon cycle is the biogeochemical cycle by which carbon is exchanged among five spheres of the Earth, carbon (C) sinks: the biosphere, pedosphere, lithosphere, hydrosphere, and atmosphere (These are not mutually exclusive, see Glossary).

Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that is key to making the Earth capable of sustaining life; it describes the movement of carbon as it is recycled and reused throughout the biosphere.

The lifetime of carbon in sediments is measured in hundreds of millions of years.

Carbon is returned from sediments to the ocean/atmosphere/biosphere/ soil when sediments are uplifted and weathered or when the sediments are drawn down into the mantle and cooked.

Return in the latter case occurs in conjunction with hot springs and volcanoes. Changes in sediment cycling rates over time have resulted in a variety of different levels of carbon in the atmosphere and for a wide range of different climate conditions. The lifetime of carbon in the ocean/atmosphere/ biosphere/soil reservoir is a few hundred thousand years.

We would expect variations in CO2 occasioned by temporary imbalances in the sediment source/sink to be manifest therefore on time scales at least this long. The challenge at the moment is that demands for the fossil fuels (coal, oil and natural gas) and cement production in our modern economy are seriously accelerating the natural rate at which carbon is returned to the atmosphere from sediments, by more than a factor of 50 (1). n.b. Cement = calcium carbonate + clay +heat > Ca3SiO5 + Ca2Al2O5 + quick lime + silica i.e. CaCO3 + heat > CaO (quick lime) + CO2 A portion of the CO2 added to the atmosphere over the past several hundred years has been absorbed by the ocean.

At the same time there have been important changes in the quantity of carbon stored in the biosphere and soils.

The early rise in CO2 was clearly due to a net release of carbon from the biosphere, including soils.

Conversion of forested land to agriculture in the eastern region of North America in the late 18th and early 19th centuries, for example, resulted without question in a net transfer of carbon to the atmosphere: the observed increase in the abundance of atmospheric CO2 in this period exceeds by a significant factor the quantity of CO2 produced as a consequence of the early use of fossil fuels.

As richer soils in the interior of

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­ the continent were opened up for development, poorer lands in the East were abandoned and forests were allowed to regrow. Ploughing the carbon rich soils of the Mid West resulted almost certainly in an additional net transfer of carbon to the atmosphere. Regrowth of the forests previously depleted in the East would have resulted in a net sink for atmospheric carbon.

Closer to present, it is apparent that clearance of land in the tropics and subtropics, deforestation, has contributed an important additional source of atmospheric CO2. On the other hand, the biosphere/soil system on a global scale is presently a net sink (1).

Agriculture and agroforestry are part of the biosphere and both affect its C flux and are influenced by that flux.

The paper by Chavan et al. (in this Issue) describes the various roles agroforestry can play. These include carbon sequestration. This is accomplished by converting CO2 into organic carbon, temporarily taking it out of the carbon cycle, and so reducing atmospheric CO2 concentration.

Exchange of C between the atmosphere and the biosphere depends on fixing the gaseous C in photosynthesis: 6CO2 + 6H2O ------> C6H12O6 + 6O2 + sunlight.

A question which is posed by this- does it make a worthwhile contribution to carbon flux /and to reducing greenhouse gas (GHG) production and what is the comparative scale of other influences?

The largest and most direct human influence on the carbon cycle is through direct emissions from burning fossil fuels, which transfers carbon from the geosphere into the atmosphere.

There are two aspects we need to determine: (1) the size of each C sink, and (2) the rate of emissions from (as a source) and uptakes (as a sink) of C by each sphere. In 2010, 9.14 x 109 tonnes C (33.5 x 109 tonnes of CO2) were released from fossil fuels and cement production worldwide, compared to 6.15 x 109 tonnes C in 1990 (2).

What proportion remained in the atmosphere and what are the prospects of reducing, or containing, the increase in atmospheric GHG? We are dividing this discussion into two parts. In Part I we shall describe the size and changing size of the C sinks and the influence of the various atmospheric GHGs. In Part II to be published next month we shall examine evidence for the rates of movement of carbon between sinks and discuss the future role agroforestry and agriculture should play in this.

Sizes of Carbon sinks

Carbonate rocks (limestone and chalk) are the major sources of C in the lithosphere, the quantity of which is by far the greatest reservoir of C on this planet.

The oceanic sink is the second largest,

Table 1. Estimated Carbon pools in the major reservoirs on earth (3) owing mainly to its vast volume and the presence inorganic carbonates.

The estimates are given in Table 1.

Composition of the Atmospheric Sink

Greenhouse Gases (GHGs) The major atmospheric constituents, nitrogen (N2), Earth’s atmosphere (O2), and argon (Ar), are not GHGs. This is because molecules containing two atoms of the same element such as N2 and O2 and monatomic molecules such as argon (Ar) have no net change in the distribution of their electrical charges when they vibrate and hence are almost totally unaffected by infrared radiation.

Nevertheless, although ozone has three atoms of the same element there is a change in the distribution of electrical charges when their vibration is increased, making it a GHG. The primary greenhouse gases (Table 2) in the are water vapour, carbon dioxide, methane, nitrous oxide, and ozone.

Without these gases, the average temperature of Earth’s surface would be about −18 °C (0 °F).

The contribution each molecular species makes to the warming of the Earth, depends on two characteristics of each species: (1) the innate response of that molecule to infrared radiation and (2) the atmospheric concentration and halflife of that molecular species. Hence, the ranges quoted in Table 2 and the consequential dependence on the time interval under consideration after joining the atmosphere (Table 3).

CO2 persists in the atmosphere much longer than does methane and so it is at a greater concentration and is therefore the most important GHG (5).

Water vapour cycles rapidly and its concentration cannot be controlled, although, undoubtedly, it will become of increasing importance, owing to its likely increase as the oceans warm up.

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Table 2. Concentrations and contribution to global warming made by greenhouse gases in the atmosphere (4)

Table 3. Atmospheric lifetime and global warming potential (GWP) per molecule of various greenhouse gases relative to that of CO2 at different time horizons (5) The atmospheric concentration of GHGs is greater than it has been for hundreds of thousands of years (see Figure 1 for values up to 2007).

At the present day, 2016, the mean atmospheric concentration of CO2 is over 400 ppm.

Uptake (release) of carbon by the biosphere is estimated to be responsible for a source (sink) of 1.1 mole of O2 for every mole of CO2 involved in the atmosphere/biosphere exchange process.

The larger value in the ratio for O2

relative to that of CO2 is associated with fossil fuel combustion, as compared to biospheric exchange, the ratio reflects the influence of hydrogen rich components in the fuel mix. (Combustion of CH4 in natural gas is responsible for consumption of 2 moles of O2 with the production of each mole of CO2).

Ocean

The oceanic sink is the second largest sink (Table 1), holding approximately

38,400 x 109 tons of C, much of which is in the form of calcium and magnesium carbonates, which give the oceans a buffering capacity for CO2.

Uptake of CO2 by the ocean is determined by the difference between the partial pressures of CO2 in the air and in surface waters of the ocean.

The abundance of CO2 in the ocean is regulated by an equilibrium among the three primary forms of inorganic carbon dissolved in sea water, HCO3- , CO32and CO2.

Net uptake of CO2 by the ocean and land biosphere between 1995 and mid 2007 amounted to 25.7 (2.14 yr-1) and 13.1 (1.09 yr-1) C t x109, respectively.

Over the same period, fossil fuels added 89.3 (7.44 yr-1) C t x109 to the atmosphere and the abundance in the atmosphere increased by 50.5 C t x109 (i.e. 89.3 –[25.7 +13.1]). Defining the airborne fraction as the fraction of net carbon added to the atmosphere that persists in the atmosphere, these results imply an airborne fraction of 56.5% (i.e.

100 x 50.5/89.3) (1).

Current trends in climate change lead to higher ocean temperatures, thus modifying ecosystems and very gradually reducing the ocean’s capacity to hold CO2. Additional release of CO2 from the ocean to the atmosphere could arise as a result of net warming of surface ocean waters.

However, the role of oceanic cyanobacteria and algae to convert the more readily available CO2 by photosynthesis to carbohydrate seems to have been ignored by many investigators.

Acid rain and polluted runoff from agriculture and industry change the ocean’s chemical composition. Such changes can have dramatic effects on highly sensitive ecosystems such as coral reefs, reducing oceanic biodiversity. It is the decrease in [CO32-] which leads to the decrease in Aragonite and Calcite saturation, as the pH is still buffered to above 7. This is the problem for organisms that use these minerals for calcification (e.g. corals, pteropods, molluscs, & foramina).

Terrestrial Biosphere

Fig 1. Atmospheric CO2 molar concentration v time (1000s of years) (5)

Soil This is the sphere of direct concern to agriculture. Land is estimated to hold of the order of 2000 x 109 tonnes C worldwide (Table 1) of which world forest trees contain about 58%.

Amazonian forests contain about 4% (47 x 109 tonnes C). Deforestation for agricultural purposes leads to land cover which stores comparatively small amounts of carbon, so that the net product of the process is that more carbon stays in the atmosphere.

However, the contemporary increase in the concentration of CO2 in the atmosphere owes mainly to emissions associated with combustion of fossil fuels.

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­ atmospheric GHGs, and the contribution made to maintaining an accommodating hydrological cycle (1)

Fig.2. Panel a: Global atmospheric CO2 concentration from 1995 to 2007, in ppm, derived by weighting monthly averages of station data in proportion to the surface area of that appropriate for the latitude zones to which the stations were assigned. The red line is with the seasonal cycle, the black line with the seasonal cycle removed.

Panel b: Hemispheric CO2 contrast (northern hemisphere CO2 concentration minus southern hemisphere concentration) from 1995 to 2007, in ppm, reflecting the fact that fossil fuel combustion is largely concentrated in the northern hemisphere. (1) Since 1995, approximately 57% of (2) that there will be additional release the carbon released as a result of the associated with deforestation in the fossil fuel source has persisted in the tropics (in countries such as Brazil and atmosphere and 15% has been absorbed Indonesia), the latter representing a by the land biosphere. repeat of what happened earlier in the It is clearly important to define the mid-latitude regime. nature of this biospheric sink and indeed Natural forests are important as a its location. Evidence suggests that it is source of environmental services. The concentrated primarily at mid-latitudes of fact is that eliminating these systems to the Northern Hemisphere. feed the world, converting them either to Possible explanations include a climate pasture or annual crops can provide a induced extension of the growing season, more immediate return to those who own enhanced uptake by photosynthesis or control the land. prompted by the increasing level of Current economic accounting fails CO2 in the atmosphere, and, potentially, regrettably to recognize the intrinsic value regrowth of vegetation representing of the environmental services provided return to conditions prevalent prior to the by these natural ecosystems. If we are mid 20th century when the biosphere is to avoid unacceptable future disruption estimated to have provided a net source to the global climate system, it will be rather than a net sink for CO2. necessary to constrain future growth in The subsequent regrowth of forests the concentration of the key greenhouse depleted previously in conjunction with gases, not only CO2 but also CH4 and N2O. conversion of land for purposes of Reduction in emissions of CO2 from agriculture is likely to be a contributory fossil fuels can make an important factor. contribution to this objective. The role of Compounding the challenge is: environmental services provided by these (1) the likelihood that soils at high natural ecosystems should be preserved latitude may be responsible for a net in regulating the concentrations of the key source of CO2 (see “Peat”, below) and

62 World Agriculture

Soil Respiration and Carbon Sequestration The estimated annual flux of CO2 from soils to the atmosphere in 1995 was estimated to be 21C t x 109yr−1, greater than previous global estimates, and 30–60% greater than terrestrial net primary productivity (6).

Between 1989 and 2008 soil respiration increased by about 0.1% per year (7) (0.1 CO2 t x 109yr−1). In 2008, the global total of CO2 released from the soil reached roughly 98 billion tonnes, (27 C t x 109yr−1) (1), about three times more carbon than humans are now putting into the atmosphere each year by burning fossil fuel and cement manufacture (1) (i.e., 9-10 C t x 109 yr-1).

There are a few plausible explanations for this trend, but the most likely explanation is that increasing temperatures have increased rates of decomposition of soil organic matter, which has increased the flow of CO2. (compare these values with RS, soil respiration rate, below).

The extent of carbon sequestering in soil is dependent on local climatic conditions and thus changes in the course of climate change.

From the pre-industrial era to 2010, the terrestrial biosphere represented a net source of atmospheric CO2 prior to 1940, switching subsequently to a net sink (1). As well as enhancing food security, in future carbon sequestration has the potential to offset fossil fuel emissions by 0.4 to 1.2 gigatons of carbon per year, or 5 to 15% of the global fossil-fuel emissions (8).

Soil CO2 fluxes have a pronounced seasonal pattern in most locations, with maximum emissions coinciding with periods of active plant growth.

Models indicate that soils produce CO2 throughout the year and thereby contribute to the observed wintertime increases in atmospheric CO2 concentrations (Fig. 3).

The derivation of statistically based estimates of soil CO2 emissions at a 0.5° latitude by longitude represents the best-resolved estimate to date of global CO2 fluxes from soils and should facilitate investigations of net carbon exchanges between the atmosphere and terrestrial biosphere (10).

Soil respiration, RS, the flux of microbially and plant-respired carbon dioxide (CO2) from the soil surface to the atmosphere, is the second-largest terrestrial carbon flux (7). However, the dynamics of RS are not well understood and the global flux remains poorly constrained.

Ecosystem warming experiments indicate that RS should change with climate. After adjusting the data for mean annual climate, leaf area, nitrogen deposition and changes in

scientific

e x 109an-1 (approximately 0.7 t Ce x 109an.-1) (13). These high emission rates can be avoided by peatland rewetting and restoration(14). Rewetting of peatlands suppresses aerobic CO2 and N2O emissions but leads to increased methane (CH4) emissions (see below).

Fig 3. 2011, carbon dioxide mole fraction in the troposphere; NASA (9) CO2 measurement technique the N. There is insufficient data on the natural observations indicate that the air rate at which there is inter-conversion temperature anomaly (the deviation from amongst the NOx; Nevertheless, there is ample evidence on their differential the 1961–1990 mean) is significantly and effects. positively correlated with changes in RS Nitric oxide, NO, is an essential (7). metabolite for normal human well-being.

The conclusion is that the flux, Individuals unable to synthesise NO from integrated over the Earth’s land L-arginine in the lining of arteries under surface, was increasing at the rate the influence of the enzyme arginase, of 0.1 Pg C yr-1 between 1989 and suffer severe hypertension, as the central 2008. It has been estimated (7) that regulation of blood pressure, smooth the global RS in 2008 (that is, the flux muscle relaxation, and vasodilatation are integrated over the Earth’s land surface interrupted. over 2008) was 98 ± 12 t C x 109 and that There is a very slow rate of oxidation it increased by 0.1 Pg C yr-1 between 1989 of NO to NO2, nitrogen dioxide. Under and 2008. natural conditions NO2 reacts with This value is ten times the value for water causing acid rain (nitric acid, the annual loss of C to the atmosphere HNO3) and as a consequence is said derived from fossil fuels and cement to be associated with emphysema and manufacture. bronchitis. NO2, is a gas in the exhaust An increasing global RS value does fumes of road vehicles which is the cause not necessarily constitute a positive of the EU’s concern for human safety. feedback to the atmosphere, as it could All gases are toxic and lethal to humans be driven by higher carbon inputs to soil rather than by mobilization of stored older when inhaled continuously at abnormal concentrations. carbon. The available data are, however, There is some evidence which shows consistent with an acceleration of the exposure to 1.5 ppm nitrogen dioxide terrestrial carbon cycle in response to (NO2) for 3 h increases airway reactivity global climate change (11).

(12), although other evidence has described no ill effect.

Peat Nitrous oxide (N2O) is an extremely Oxides of Nitrogen: potent GHG (Table 3). Use of excessive Although our concerns in this review rates of N fertilizers causes a local rise in are principally with the C cycle, fuller atmospheric N2O concentrations. understanding of the causes of global Drainage of peat soils results in CO2 and N2O emissions of globally 2-3 t CO2 warming requires reference to oxides of

Methanogenesis: Over thousands of years peatlands have developed deposits of 1.5 to 2.3 m- the average depth of the boreal peatlands.

One of the most common components is Sphagnum moss, although many other plants can contribute. Soils that contain mostly peat are known as histosols.

Peat forms in wetland conditions, where flooding obstructs flows of oxygen from the atmosphere, slowing rates of decomposition leading to methane fluxes.

Yet methane fluxes are negligible in SE Asian peatlands at low water levels and only amount hourly to up to 3 mg CH4 m−2 h−1 at high water levels.

This is low compared with emissions from boreal and temperate peatlands (13,15). The scientific data base for methane (CH4) emissions from peatland is much larger than that for CO2 or N2O. In an anaerobic environment the availability of fresh plant material is the major factor in methane production. Old (recalcitrant) peat plays only a subordinate role.

The global CO2 emissions from drained peatlands have increased from 0.288 C t x 109 to 0.354 C t x 109, from 1995 to 2008 (>20%), excluding effects of N2O (16). This increase has particularly taken place in developing countries, of which Indonesia, China, Malaysia, and Papua New Guinea, are the fastest growing top emitters. This estimate excludes emissions from peat fires (conservative estimates for the effect of fires amount to at least 1.1 C t x 109 an-1 for south-east Asia).

For drainage related peatland CO2 (excl. extracted peat and fires): Indonesia emits 0.136 Ce t x 109an-1; The EU is the second largest emitter with an estimated 0.0474 Ce t x 109 .an-1and Russia, 0.044 Ce. t x 109 an-1).

Total CO2 emissions from the worldwide 500,000km2 of degraded peatland may exceed 0.7 Ce t x 109 an-1. This value is almost 6% of all global carbon emissions.

(13, 17) A differentiation can be made between generally nutrient poor, acidic raised bog peat and often more nutrient and base rich fen peat (Table 4). The lower nutrient content and higher acidity of the bog peat indicates lower methane production and emission.

This is so for boreal peatlands and becomes most obvious when comparing bogs and fen with aerenchymous shunts*.

In temperate peatlands no differentiation between bogs and fens can be made on the basis of the available data.

Availability of comparable data for tropical peatlands is still limited.

Current knowledge indicates emissions will be small even after rewetting (<0.5mg

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­

Table 4. Emission factors of methane from peatlands of different types and vegetation. ‘Dry’ means a mean annual water level below -20 cm, ‘Wet’ one above – 20 cm (13) CH4 m2h-1)(16). Rewetting of previously drained peat soils may lead to excessive initial methane emissions when vegetation is flooded and dies off to become substrate for methanogens.

Over a longer period there will be a clear climate benefit from rewetting drained peatlands.

Fermentation is a process used by certain kinds of microorganisms to break down essential nutrients. In a process called acetoclastic methanogenesis, microorganisms from the classification domain archaea produce methane by fermenting acetate and H2CO2 into methane and carbon dioxide: H3C-COOH › CH4 + CO2 Depending on the wetland and type of archaea, hydrogenotrophic methanogenesis, another process that yields methane, can also occur. This process occurs as a result of archaea oxidizing hydrogen with carbon dioxide to yield methane and water: 4H2 + CO2 › CH4 + 2H2O

Conclusions

1. The rapid atmospheric increase in GHGs continues, caused primarily by the burning of fossil fuels and cement manufacture.

2. Deforestation(18, 19, 20, 21) and the drainage of peatlands(17) have a large contributory influence on GHG production.

3. The general warming of the global environment and the increasing abundance of atmospheric CO2 have several consequences: a. an increase in general photosynthetic rate, absorbing atmospheric CO2. b. an extension in the season of growth in the Northern Hemisphere(1), c. an increase in the rate of soil respiration(7) and loss of C to the atmosphere at a rate tenfold that of burning fossil fuels and cement manufacture. d. an increase in the rate of thawing of northern peatlands will itself cause an increased evolution of CH4.

64 World Agriculture

e. the increased rate of evaporation of water from the oceans will increase cloud cover accelerating global warming.

4. The annual loss of C from the global soil as a GHG is at least three times, and soil respiration rate of C at least ten times, the loss caused by fossil fuels and cement manufacture. Therefore a greater control of this soil loss would be expected to have a significant impact upon the rate of climate change.

The role of agroforestry (22) in sequestration of C needs to be quantified and should also have a beneficial impact on the losses under Conclusion 4. We conclude shading of soil brought about by agroforestry could lower its temperature and so reduce microbial activity and GHG production rate.

Solar energy used in heating exposed soil and so stimulating microbial action is used instead for transpiration which requires water to be raised perhaps 20-30 m to the canopy of trees.

Soil respiration rate over the world’s land surface in 2008 was estimated (7) to produce 98 ± 12 t C x 109. A 1 % decrease in this would equal 10 % of the annual GHG produced by burning fossil fuels and cement manufacture.

References

1. Huang, Junling and Michael B. McElroy (2012). “The Contemporary and Historical Budget of Atmospheric CO2” (PDF). Canadian Journal of Physics 90 (8): 707-716.

Bibcode:2012CaJPh..90..707H. doi:10.1139/p2012033.

2. G.P. Peters et al.(2010) Global carbon budget (summary), Tyndall Centre for Climate Change Research 3. Falkowski, P.; Scholes, R. J.; Boyle, E.; Canadell, J.; Canfield, D.; Elser, J.; Gruber, N.; Hibbard, K.; Högberg, P.; Linder, S.; MacKenzie, F. T.; Moore b, 3.; Pedersen, T.; Rosenthal, Y.; Seitzinger, S.; Smetacek, V.; Steffen, W. (2000). “The Global Carbon Cycle: A Test of Our Knowledge of Earth as a System”. Science 290(5490): 291– 296. Bibcode:2000Sci...290..291F.doi:10.1126/ science.290.5490.291. PMID 11030643.

4. Wallace, John M. and Peter V. Hobbs (2006) Atmospheric Science; An Introductory Survey.

Elsevier. Second Edition, 2006. ISBN 978-0-12732951-2. Chapter 1 5. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood,

J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland (2007). “Changes in Atmospheric Constituents and in Radiative Forcing”. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 6. Rice, Charles W. (2002) Carbon in Soil: Why and How? Geotimes (January). American Geological Institute.

7. Bond-Lamberty, B. & Thomson, A. (2010) Temperature-associated increases in the global soil respiration record. Nature 464, 579-582.

8. Lal, R. (2004) Soil Carbon Sequestration Impacts on Global Climate Change and Food Security Science 11 Jun 2004: Vol. 304, Issue 5677, pp.

1623-1627; DOI: 10.1126/science.1097396 : lal.1@ osu.edu 9. Dlugokencky, E. (5 February 2016). “Annual Mean Carbon Dioxide Data”. Earth System Research Laboratory. National Oceanic & Atmospheric Administration. Retrieved 12 February 2016.

10. Raich, James W. & Christopher S. Potter (1995) Global patterns of carbon dioxide emissions from soils. Global Biogeochemical Cycles. 9.

11. Lal, Rattan (2010) Managing Soils and Ecosystems for Mitigating Anthropogenic Carbon Emissions and Advancing Global Food Security BioScience 60 (9): 708-721.doi: 10.1525/ bio.2010.60.9.8 12. Frampton, Mark W., Paul E. Morrow, Christopher Cox, F. Raymond Gibb, Donna M. Speers, and Mark J. Utell. Effects of Nitrogen Dioxide Exposure on Pulmonary function and Airway Reactivity in Normal Humans (1991) American Review of Respiratory Disease, 143, (March, 1991) No. 3, 522-527.

13. COUWENBERG, JOHN, RENÉ DOMMAIN, & HANS JOOSTEN (2010) Greenhouse gas fluxes from tropical peatlands in south-east Asia. Global Change Biology, 16, Issue 6 June, 1715–1732 14. Trumper, K., Bertzky, M., Dickson, B., van der Heijden, G., Jenkins, M. & Manning, P. (2009) The Natural Fix? The Role of Ecosystems in Climate Mitigation. A UNEP Rapid Response Assessment, United Nations Environment Programme, UNEPWCMC, Cambridge, UK, 65 pp. http://www. unep.org/pdf/BioseqRRA_scr.pdf 15. Couwenberg J, Dommain R, Joosten H (2009) Greenhouse gas fluxes from tropical peatlands in south-east Asia. Global Change Biology, doi: 10.1111/j.1365-2486.2009.02016.x 16. COUWENBERG, J., RENE´ D O M M A I N and H A N S J O O S T E N (2009) Greenhouse gas fluxes from tropical peatlands in south-east Asia. Global Change Biology, doi: 10.1111/j.13652486.2009.02016.x,pp 1-18.

17. Joosten, Hans, (2009, 2010) The Global Peatland CO2 Picture Peatland status and drainage related emissions in all countries of the world.

Greifswald University, Wetlands International, Ede, August 2010 www.wetlands.org 18. FAO (2010), Forestry Department, Corporate Document. Global Forest Resources Assessment.

19. FAO (2015) assessment of forests and carbon stocks, 1990–2015, I4470E/1/03.15 20. FAO (2001) Forestry Department, Corporate Document Repository State of the World’s Forests (SOFO). Climate change and forests, pp1-12.

21. Brown, Felicity (2009-09-02). “Total forest coverage by country | Environment |Guardian. co.uk”. Guardian. Retrieved 2012-08-19.

22. Zomer, Robert J., Antonio Trabucco, Richard Coe and Frank Place, (2009) Trees on Farm: Analysis of Global Extent and Geographical Patterns of Agroforestry. © World Agroforestry Centre ICRAF Working Paper no. 89, pp 1-64.

book review

A review of Dame Fiona Reynolds’ book: The Fight for Beauty, Publ.

Oneworld Publications, London 2016; and on the effects of land use on climate change

D

ame Fiona has published a most apposite and timely book on the Man’s need for beauty of the natural world.

She has asked me to review it – a hard-headed scientist to review a book on beauty, is you might think, a bit incongruous.

“Beauty lies in the eyes of the beholder”, as Plato most astutely stated – it is not subject to scientific analysis, or quantification.

Nevertheless, what is beautiful is subject to teaching, or is learnt by experience. My mother once told me she enquired of a young lady we had staying in our home why she was weeping whilst gazing through a rear window of our house. The young urbane lady replied – that the scene was so empty – there was not a house in sight! That need would be amply compensated today.

The countryside of these islands is beautiful and bewitching. I know of no land in which there is such a variety in such a small area, undoubtedly associated with its soils covering the whole range of geological formations from Precambrian to Recent.

No sensible person wants to see it destroyed, or covered with buildings, which is occurring with urban sprawl – despite the so-called green belts.

The chapter on farming gives an eloquent, interesting and most worthwhile description of British farming from its earliest days till the present day.

Fiona Reynolds relates that the scene in England has changed repeatedly over the centuries according to economic and social dictates, with some delightful quotes from John Clare, the poet (17931864) and Thomas Hardy (18401928), two, whose writing, like Dame Fiona’s, evoked a great passion for countryside.

The book and this chapter are most appropriate for the present day following the vote for the UK to leave the EU. Our countryside is precious,

but it must also produce food- here is the rub!

Looking at the global situation as a scientist the vital issues are: 1. to maintain biodiversity.

2. to retard the rate at which greenhouse gases are entering the atmosphere, and if possible return them eventually to the pre-industrial level.

3. to adequately nourish the world population.

4. to reduce demand for natural resources.

If the world fails to achieve these four objectives, then it could be that to have concern for beauty in the countryside may be a futile objective.

The next chapter, most appropriately, is on woodland. Oliver Rackham, The History of the Countryside, a fine book, is given reference.

I particularly enjoy deciduous woodland, and as a mountaineer I used to enjoy sleeping just above the upper rim of conifers – their scent and the wind blowing through them were quite soothing.

The authorities, quite rightly as is mentioned in “The Fight for Beauty”, have increased the proportion of broad-leaved trees in England which has approximately 13000 km2 of woodland (1) covering approximately 10% of England’s land area (2,3).

To bring this up to the international average would require a further 19500 km2 of additional forest, or if this was to be on agricultural land (which covers >70 % of the land area) it would represent taking 21.7% of the existing cropped area of England for trees.

Broad-leaved forests, in particular, are an important reservoir for wildlife and with conifers reduce the risk of flooding downstream.

The penultimate chapter is quite rightly on urbanisation – a consequence of population growth.

This is likely to take up agricultural land and increase flooding risk. In the first chapter fracking is discussed.

Dr David Frape

Another hideous necessity of the human demand for energy.

However, fracking for gas has many advantages over oil. Amongst these it is less conducive to impact climate, as the required infrastructure is far less than with North Sea oil, the product is less polluting and a point missed by many is that gas inevitably produces less CO2 per kW than does oil.

Trees are a valuable sink for sequestering carbon, as Dame Fiona points out. Shading of soil brought about by agroforestry could also lower soil temperature and so reduce microbial activity and GHG production rate.

Solar energy, used in heating exposed soil which stimulates its microbial activity, is used instead for transpiration which requires water to be raised perhaps 10-30 m to the canopy of trees. Soil respiration rate (Rs) over the world’s land surface in 2008 was estimated (4) to produce 98 ± 12 t C x 10 9, that is Rs = 1.94 t C ha-1an-1, ± 0.2 t.; but an additional 19500 km2 of trees in England would compensate for the annual CO2 production brought about by burning fossil fuels and cement manufacture to extent of only 1.5-2.0% World forests would need to increase by 26%, or by 10,000,000 km2 to equal the annual production of CO2 produced by this effect of industrialisation. An increase of this magnitude is most unlikely to occur!

The Rs value is likely to include a part of the Ce accounted for by drainage of peatlands which yields vast quantities of GHG, principally CO2 and N2O emissions, as is referred to in “The Fight for Beauty”.

This amounts globally to 2-3 t CO2e x 10 9an-1 (approximately 0.7 t Ce x 10 9an-1) (5). If drainage was halted and peatlands were to be returned to their natural state it would help, but at the very maximum, only to the extent of about 6-7% of the forest effect, i.e. it could reduce the requirement for world forest expansion to 24-25%.

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book review In order to achieve some success with items (1) and (3) the reliable evidence for (1) must be based upon comparing equal outputs of food, in order that (3) is achieved. The necessary evidence for this has been published in World Agriculture: “Given that most empirical evidence shows that extensive farming produces lower yields and less local environmental impact than intensive systems, there are two basic land management strategies: land can be farmed extensively over a large area thereby producing less food, but more ecosystem services on the same land (a “land sharing” strategy), or farmed intensively over a smaller area and the remaining land can be “saved” to be managed exclusively for ecosystem services (“land sparing”). Recent research indicates that when the extra land needed to maintain yields under extensive systems is taken into account, land sparing strategies may often be optimal in terms of balancing food production while maintaining overall ecosystem services. Furthermore, if farm management increasingly reduces intensive agriculture’s impact on the environment (say through new technologies that reduce the greenhouse gas emissions from conventional farms) the conflict between intensive and extensive systems will be additionally reduced.”

(6) An example of the last point would be no tillage systems examined in several papers published in World Agriculture, especially those by our Chinese colleagues (7-9). Weeds in stubble are, if necessary, sprayed with a herbicide, the ground subsequently harrowed to produce a seedbed and then sown.

This procedure reduces the consumption of fossil fuels and reduces the oxidation of organic

66 World Agriculture

­ matter associated with traditional ploughing, causing the evolution of large quantities of CO2, a recommendation also advanced in “The Fight for Beauty”.

Requirement (4) implies that those of (1) and (2) are anthropogenic in origin.

Hence, if the world is to prevent a possible catastrophic change in the environment tree planting and forest extension would be inadequate on their own. Further and direct action will be essential. Nevertheless, the reduction in the resulting agricultural area must mean that without (4) intensive production is necessary in order to achieve the requirement of (3).

On balance climate change is likely to reduce worldwide yields of crops – Chinese evidence published in this Journal (8,9) indicates this is already the case in China. The Earth is very likely to have a smaller area available for producing food for a larger world population (the population of Africa alone is expected to rise by about a further billion between 2030 and 2050) – a world in which each individual places much greater demands on natural resources.

Therefore the UK may have, in large part, to feed a growing population itself from a smaller area of agricultural land, whereas at present perhaps about half its foodstuffs are imported. The most reliable current scientific advice would be essential for production ensuring conservation methods are employed for sustainable production – taking care of the total environment.

“The Fight for Beauty” is an important book, particularly at the present time. World population increases the demand for space on this Earth which does not itself “grow” – in fact land area is likely to decrease, as the seas encroach on it. Nevertheless, with the best scientific advice and with a reduction

in individual demand for natural resources, agricultural production should be up to the task, assuming existing problems of distribution are overcome.

The human being needs countryside to maintain sanity- its monetary value cannot be calculated in an accountants ledger, so its preservation requires the inspired efforts of a few, including that of “The Fight for Beauty” – lets ensure it gets it; but with scientifically-based intensive production where necessary.

References

1. Anon. (2012) Agriculture in the United Kingdom.

Produced by: Department for Environment, Food and Rural Affairs Department of Agriculture and Rural Development (Northern Ireland) Welsh Assembly Government, The Department for Rural Affairs and Heritage The Scottish Government, Rural and Environment Research and Analysis Directorate.

2. Smith, Steve (2001)The National Inventory of Woodland and Trees – England, pp.1-8 Publ.

Forestry Commission Edinburgh, UK 3. Smith, Steve, Justin Gilbert, Graham Bull, Simon Gillam and Esther Whitton (2010) National inventory of woodland and trees (1995–99): methodology.

Publ. Forestry Commission, Edinburgh, UK. 4. Bond-Lamberty, B. & Thomson, A. (2010) Temperature-associated increases in the global soil respiration record. Nature 464, 579-582.

5. COUWENBERG, JOHN, RENÉ DOMMAIN, & HANS JOOSTEN (2010) Greenhouse gas fluxes from tropical peatlands in south-east Asia. Global Change Biology, 16, Issue 6 June, 1715–1732 6. Benton, T; Dougill, A J; Fraser, EDG; Howlett, D J B (2011) The scale of managing production vs the scale required for ecosystem service production.

World Agriculture 2, No.1, 14-21.

7. Dongmei Jiang , Associate Professor Xiaoshun Li, Professor Zhengfu Bian , Professor Jinming Yan, Professor Futian Qu, Professor Xiaoping Shi, Professor Shaoliang Zhang, & Guancong He (2015) China’s cultivated land change and its carbon budget measurement based on the system dynamics. World Agriculture 5, No.1, 19-24.

8. Dr Zhao Aiqin, Professor Zhu Ming & Professor Wei Xiuju (2015) Impact of climate change on crop production and agricultural engineering technological countermeasures used in mitigation in China, World Agriculture 5, No.1, 43-49.

9. Dr Rui-Ying Guo and Professor Feng-Min Li (2014) Agroecosystem management in arid areas under climate change: Experiences from the Semiarid Loess Plateau, China World Agriculture 4, No.2, 19-29.

economic & social

Some notes on the politics of survival 1. We can only make policies that have the consent of the power brokers a. In a democracy such as the UK, power lies with those who win votes. b. The Brexit debate has shown how voters disregard expert views but accept uncritically populist statements from pressure groups.

2. The need to reduce fossil fuel use implies unwanted changes in lifestyles. a. The public response is likely to be fashioned by pressure groups who offer ‘easy’ options – anti-austerity for example. b. The use of direct regulation to secure an immediate reduction in fossil fuel use would affect many people adversely. It would impact most severely on poor households who, despite spending a larger share of their income on food and energy, depend on older and less efficient apparatus for heating homes, cooking and washing. A government that sought to enforce such a regime would reduce its own chances of survival. c. We already tax some fossil fuels so that the price to the user is above the cost of supply. This brings pressure for long run shifts in the way in which energy is priced and used. If such taxation is to result in a very large reduction in fuel use, it would need to be sufficiently high to outweigh the cost and inconvenience of more energy efficient systems.

Again, it is the poor who are most at risk. ( even at current prices a winter fuel payment is seen as necessary). d. The implication is that policy action is not likely to bring about the level of change needed in fossil fuel consumption.

3. This discussion implies we seek means to provide what people actually want with less dependence upon fossil fuel. Such technologies may either sustain current consumption patterns by greater efficiency, the use of non-fossil sources of energy or offer opportunities that lead to a change in what people want to consume. a. An attractive approach is to capture solar energy either by solar panels or by using plants to deliver a variety of forms of energy – including liquid fuel. These technologies have potential but the probable scale of substitution for fossil fuel is limited. a.i. A shift of farm land from food to energy production would lead to – higher food prices, resulting in hardship for the poorest people. a.ii. Solar energy depends on hours of sunlight and the capacity to store and transmit electricity from where and when it is available to places where it will be consumed.

b. A different approach is to change the pattern of consumer preferences.

For example by substituting virtual experience for actual. We already see some examples of this where meetings are held via electronic conferencing rather than physical encounter. b.i. The field is open for the development of artistic and artisan skills of all sorts. Never before has society encountered a situation in which most of its people do not have to work most of their time in order to survive. At the same time modern computer systems offer new ways to be creative at relatively modest levels of skill. b.ii. Electronic tourism already exists in the form of many natural history programs. ‘Discovery’ type television may replace the need for physical movement to explore distant places.

4. How do we know if we are making progress? a. Traditionally our approach to the environment has been defensive not pro-active. Environmental goods are often recognised only when some exogenous change reduces supply or leads to a novel market. Thus we become concerned about flower rich meadows only when most have disappeared, we are anxious about rural villages when outside money prices their houses beyond the purse of local communities. b. Because we do not need to devote so much of our time to physical production the opportunities for creating socially valuable ‘goods’ at the personal level has never been greater. Many of these non-market roles add real value to community life but are often ignored in calculations of welfare. The examples are numerous, for example : b.i. Amateur dramatics and choirs, b.ii. Concerned groups that seek to keep villages tidy, b.iii. Networking among residents that brings aid to people in need, b.iv. Village sporting teams and b.v. Activities for children that help them discover and identify talents and interests. c. Measurements of national income are made in money terms. For items that do not have a price but have value, such as the stream of benefits house owners receive from living in their own properties, estimates in money terms are made. Similarly environmental economists have sought means of providing surrogate money values for environmental services. This is difficult and controversial but at least represents an important stream of real benefit to society that is missed in market

Professor Sir John Marsh

estimates. d. The valuation of social non-market benefits, such as those described above is even more difficult. They have to be identified, a particular activity or commitment may lead to positive benefits – and be regarded as a cost to be endured. However, in valuing a lifestyle that is consistent with much lower dependence on fossil fuels they will become of growing importance. e. To change our pattern of consumption to one which is consistent with a reduced level of fossil fuel consumption we need to free ourselves from the idea that the quality of life depends upon the abundance of possessions. Such a traditional approach is too often dismissed as unrealistic. In fact it is much more realistic than ‘business as usual’ if we take seriously the threat to the world community from the unconstrained exploitation of fossil fuels.

5. Conclusion. a. Not unsurprisingly the issue of changing lifestyles takes us into the territory of religion. To make progress politicians have to articulate what it is that is truly valuable. This is a leadership challenge missing from a political system that is professionally neutral about religion. It delivers power to those who guess what the voters would like to hear and reflect that to them as policy intention. It is wholly irresponsible about the impact of such populist policies upon the real welfare of society. b. It is also a challenge to religious leaders whose energies too often seem to be devoted to the defence of historical dogma and structures. What is urgently needed is to articulate values that others adopt as forming the basis of a lifestyle that is both more fulfilling and more sustainable. c. It is the nature of research that those who participate develop their own language and their own view of the world. Confronted by problems each group seeks and sometimes identifies solutions within that framework. This note argues that because global warming affects all the elements that underpin the lifestyles we seek and enjoy we need a shared responsibility that includes natural sciences, socio-economic analysis, political and religious conversation and communicators at all levels.

Parallel debates among experts are not enough, it has to involve the whole community in ways that offer not just a continuation of current consumption patterns but a lifestyle that is more rewarding and sustainable.

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