GREEN STRUCTURES FOR A RESILIENT CA MAU (VIETNAM) José Fernando Higuera Osorio KULeuven- MAHS ABSTRACT This paper is part of the master thesis made as part of the Master in Human Settlements undertaken in the Katholieke Universiteit Leuven- KULeuven. This document is a support of the studio presentation CA MAU, VIETNAM. Back from Planning to Planting made in June 10th 2013 in KU Leuven, Belgium; which was a design studio focused in landscape urbanism in the Ca Mau peninsula in Vietnam. The aim of this paper is to give a deeper elucidation of the related aspects of the peninsular scale regarding with green structures, as a frame to the future develop of the entire region. The first part is an introduction of several aspects in the region, placing it at the present context of growing population, changes in urbanization patterns, pollution, sea level rise, free market economy, etc. Secondly it will take place a short explanation of the evolution of the Ca Mau peninsula and the shaping forces that keep structuring it and to the whole landscape. The third part is about the most challenging aspect that Ca Mau faces, as is the climate change with the expected sea level rise, due to the high vulnerability of the peninsula to deal with this alteration. The next part considers the Acid Sulphate Soils (ASS), which is a natural condition of the whole peninsula that has been disturbed due to the land use changes and cultural practices related with agricultural and aquacultural activities with severe implications in the peninsular environment. The fifth section concerns about the local flora present in Ca Mau peninsula, its ecology, uses, distribution, cultural and economical aspects and main characteristics in order to frame the strategy of Planning/Planting. The sixth part examine the strategic project proposed to deal with the different conditions explained previously, the possible repercussions and implications that can bring to the whole landscape. Finally the conclusions can give a hint of how this strategic project can reshape the peninsular landscape with the proposed growing planting strategy. Although many aspects from the peninsula and the project are not be considered in this paper, it can be a start for further investigations regarding with local flora planting strategies in order to deal with the different challenges that the future brings to the human civilization.
INTRODUCTION The Asian continent has been through gigantic demographic changes in the last 50 years, being one of the most drastic rates of displacement of people from villages to cities. The United Nations estimates that urbanization in Asia between 2005 and 2010 will increase at rates of about 2.5% each year. With these rates, more than half of Asia’s total population will live in urban areas by the year 2025, and by 2030, it is expected that 54.5% of Asia’s population will be urbanized. This means that by 2030, one out of every two urban residents in the world will be living in Asia (Un HABITAT et al, 2008).
the overall Asian rate. In the Vietnam case, the percentage of urban population in the country was 30.4% in 2010, being 44.1% for the south eastern of Asia. While the overall urban population of this region will grow by 2.38% per year between 2010 and 2015, the urban population in Vietnam will grow 3.26% in the same period of time (UN, 2011).
After the implementation of the Doi Moi1 policy, which was officially adopted in December 1986 at the Party’s sixth national congress and which was primarily designed to turn Vietnam’s centrally-planned economy into a market-based one (Hong, 2012), this Although Asia’s least-developed countries country has become the second economy have considerably lower levels of urbanization, in the region; leaded by the People’s these countries are urbanizing faster than 1 Renovation. 1
Republic of China (World Bank, 2013). This has brought several consequences to the whole country, which is facing a rapid process of transformation from a traditional to a modern globalized society, leading to a fast urbanization never seen before and transforming the society from a water- based network to a road- based network with the corresponding urban sprawl around the cities.
land use into a more “profitable” function (BINH et al, 2005); saline intrusion into sweet water-cultivated landscape due to the increment of shrimp farming areas thanks to the Vietnamese governmental resolution 09/NQ-CP (HENS et al, 2009); oxidation of potential acid sulphate soils, due to the soil leaching and other cultural practices in the commonly present acid soils that leads to the acidification of water making it unsuitable for The consequences in the Ca Mau region have domestic purposes (MINH et al, 1997); and it been highly challenging, with the succession has led to the rapid and chaotic growth of the of productive landscape characterized by urban area of the city as well the periurban the move from rice cultivation and small and rural areas (LEBEL et al, 2002; COULTHART scale aquaculture production (with a minor et al, 2006). presence of orchards) to an economy based mainly in brackish-water shrimp mono- The province of Ca Mau is a low coastal aquaculture (BINH et al, 2005). This switch has region in the southern area of Vietnam. It led shrimp to turn into a vital commodity; is surrounded by the Gulf of Thailand at the benefits of which include higher incomes per west and by the East Sea, with an area of 5294 hectare, strengthening of the state financial Km2, a population of 1214900 people with a capacity to invest and the inclusion in density of 229 people/ Km2 (Ca Mau website). global clusters of production. However, the Its freshwater sources are by precipitation, cultivation of shrimp has been increasingly underground aquifers and surface flows from threatened by the very detriments arising the Bassac River. With a coastline of 170 Km from it. Inland conversion of land to intensive long, it is influenced by two different tidal farming shrimp ponds has contributed to regimes that drive the saline intrusion into the surface and ground water pollution due to main canal and creek system mainly through the use of relatively large amount of feed, My Thanh, Ganh Hao Rivers from the East Sea pesticides and antibiotics (PHAM et al, and through Song Doc, Cai Lon, Cai Be Rivers 2010); loss of mangle ecosystem due to the and the canals from the West Sea (TRI, 2012). increments in mangrove forest to change its The semidiurnal tidal range of the East Sea in
12
0
5000 km Worlds biggest delta areas
Delta areas in the world. From KONNINGS, 2012.
2
high tide can reach amplitude ranges from 3- 3.5 m. while during low tides varies from 1.8- 2.2 m. The irregular diurnal West Sea tide reaches amplitudes of 0.8 m. approximately (SIWRR, 2008). The recent growth Ca Mau´s economy between 2001- 2010 has been about 12%, which is stronger than the previous period (1996- 2000, 8%). The provincial GPD reached US$1107 million and GDP per capita augmented from US$640 in 2006 to US$923 in 2009. The projected GDP growth for the period 2010-2030 is 8% on average, although after that the growth rate might reduce to around 5% for 2030- 50. The agricultural sector is the most important of the local economy, with 42% of Ca Mau´s GDP and is the main economical activity of the 75% of the population (THO HUNG, 2012). The forest area of Ca Mau is mainly mangrove forest (88738 ha) and melaleuca forest (56900 ha) (SIWRR, 2008). Mangrove forest is used mainly as a protective system within 1 Km wide coastal belt in the South East and Southern coasts. On the west coast, approximately 2200 ha of new mangrove are missing and should be planted to close the gaps where was previously present and to complete the belt (THO HUNG, 2012).
EVOLUTION OF THE MEKONG RIVER DELTA AND THE CA MAU PENINSULA The Mekong River Delta (MRD) is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoondriven river discharge and human impact (agriculture, fishing, sand dredging, tourism, etc.) (UNVERRICHT et al, 2013). Is a combined system (river-dominated/ influenced, wavedominated/ influenced, tidedominated/ influenced) with several process changes in time (XUE et al, 2010; YAMASHITA et al, 2012). The Mekong River originates in the Tibetan Plateau, runs through China, Myanmar, Thailand, Laos, Cambodia, and finally enters the South China Sea in southern Vietnam with a total length of 4750 Km approximately. Approximately 85% (475 billion m3) of the water discharge occurs during the wet season (May to October), and 15% (78.8 billion m3) in the dry season (November to April). The discharge of sediment to the sea is 160
According with SIWRR- Southern Institute for Water Resources Planning of Vietnam, this complex interaction between two tidal systems, together with the flat geomorphology of the peninsula, causes the following situations related with the water logics: A vast and extended flood regime driven by the south monsoon (May- September), strong winds and cyclones that can inundate dike routes, residential and agricultural areas, erode banks and contaminate drainage; shortages of fresh water and salinity intrusion from the sea in dry season; Acid Sulphate Soils (ASS) that can produce highly acidic waters in the beginning of the rainy season; drought and increased sediment loadings due to deforestation (SIWRR, 2008). Location of dams in the Mekong River. From RENAUD et al, 2012..
3
Mekong River profile from headwaters to mouth. From QUANG TRIEU, 2012.
Mekong River Profile from headwaters to mouth. From QUANG TRIEU, 2012.
ac
ss
Ba r ve
Ri
20
10
10
Scheme of the growing of Ca Mau peninsula. From PETROVSKY, 2013. KULeuven. Sketch of the growing system of Ca Mau Peninsula. From PETROVSKY, 2013, KuLeuven.
4
million of tons/year having one of the highest rates of release according with its length and flow rate. This amount of discharge may diminish due to the existing and proposed dams along the river (XUE et al, 2010; UNVERRICHT et al, 2013). Over the past 3000 years, the evolution of the MRD has shown a morphological asymmetry, resulting in a fast progradation around Ca Mau cape; resulting in 16 m/year approximately in the region of the MRD mouth and 26 m/year approx. in the tip of Ca Mau peninsula. At the same time the east shore of the peninsula has been under erosion at a rate 1.1 km2/year, while the west shore presents a progradation of about 1.2 km2/year. This area is influenced by the southeast and northeast Asian Monsoon, having two different scenarios annually. The first one takes place when the southwest monsoon brings the precipitations (the rainy season) between May and October. Most of the suspended sediments are discharged from the MRD to coastal waters. The second one occurs in the dry season between November and April, when tidal asymmetry (coastal currents can reach 0.55 m/s) and the reduction of fresh water flow rate generate saline water intrusion. Sediments are either pumped upstream or transported to the southwest by the coastal currents strengthened by the northeast monsoon. As said before, the Ca Mau peninsula is influenced by the Thailand Gulf tidal regime and the East sea tidal regime, converging in the southern tip of Ca Mau cape. At this point larger amounts of transported sediments are accumulated due to the reduced tidal energy caused by the meeting of the two tidal systems. Only fine sediments are able to pass the tip of the cape, reaching the western shore of the peninsula (XUE et al, 2010). Due to this transport of soil from the inlands to the sea, high percentages of organic matter are present in the sediments (YAMASHITA et al, 2012).
is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes. Vulnerability is a function of the character, magnitude, and rate of climate change and variation to which a system is exposed, its sensitivity, and its adaptive capacity� (IPCC, 2007). Climate change is the major environmental threats for Vietnam caused for greenhouse gas emissions from human activities. The entire peninsula is highly vulnerable to climatic oscillations and extremes in the water regime; it is highly exposed to the sea level rise, being more serious for countries that have high population densities in coastal and lowlands like Vietnam. These climatic oscillations lead to stronger fluctuations in rainfall amounts and an increase in climate extremes like floods and droughts. The sea level rise will affect directly coastal areas, increasing coastal infrastructure costs and inundating, with the resulting loss of land (MACKAY, et al, 2011). The death toll by natural disaster will increase along with poverty due to loss of income and houses. The most vulnerable group includes farmers, ethnic minority, children, women and the elderly. The main impacts will be around the Red River and the Mekong deltas (The Mekong delta is almost below 5 m. above sea level, being one of the most vulnerable in the world). A sea level rise will probably increase salt water intrusion, which is before now a problem in the peninsula due to the constructions of canals and the fresh water extraction for drinking and irrigation (MACKAY et al, 2011; Ministry of Natural Resources and Environment et al, 2010). All these changes will affect the natural systems and the agriculture. Changes in growing periods, crop calendars and distribution will take place with the risk of increasing pests and viruses and some species can become locally extinct as a result of the changing conditions. Rice production is predicted to decrease in 9% in the whole peninsula, being affected too fruit and fresh water aquaculture (Ministry of Natural Resources and Environment et al, CLIMATE CHANGE 2010). As the agricultural sector is the most Climate change vulnerability is defined by important of the local economy, any negative the IPCC as “the degree to which a system impact on these agricultural systems will affect enormously the livelihoods of the people and 5
the regional and national economies; with the challenge in the local and national food security.
care. The hazard of sea level rise can come from three related sources: By one hand, the systematic increment of the green house effect along with the gradual increase of global average temperature of hearth. Most of the global thermal energy is collected in the oceans; therefore an increase in global temperature will result in warmer oceans. This can cause an expansion of sea water volume, increasing the sea level by 1 to 3 m. If the sea level rises by 1m, around 5.3% of land, 10.8% of population, 10.2% of GDP, 10.9% of urban area, 7.2% of agricultural area, and 28.9% of low ground in the whole Vietnam will be affected (IPCC, 2007). By the
Loss of housing is another major impact of climate change in the peninsula. Due to the limitation of high land areas (mostly in rural areas), building in higher places will be difficult. Population living in the coastal areas are the most vulnerable to climate change impacts. Climate change is also expected to affect population´s health due to the fact that the increase of temperature can make easier the growth and development of several viruses and vectors with the result of higher incidences of diseases as malaria or dengue. Hotter climates, higher sun radiations, abrupt weather changes are factors that can cause direct harm to human health such as loss of water balance and salt, higher risks with cardiovascular diseases in elder people (hot and moist weather), skin melanoma, etc. (Ministry of Natural Resources and Environment et al, 2010). This will require new long term strategies for public health
Ca Mau Provincial Vulnerability Synthesis
30
20
10
-
Table 21. Summary of sector Control Measures.
Impacts Sector
Salinity
Storm Surge
Overall Protection
••
••
•
Medium
••
Intermediate and/or partly controlled
••
•••
•
High
•••
Major but largely controlled
••
•••
•••
•
High
••••
Major and largely uncontrolled
•
•
••
•
High
•
•
••
•
High
Erosion & Sedimentation
Flooding & Inundation
Settlements & Population
•
Poverty & Income
•
Agriculture & Livelihoods Industry & Energy Transportation
•
Minor and/or well controlled
Ca Mau ditrict vulnerability synthesis. From MACKAY et al, 2011.
6
other hand, the icebergs in Greenland and West Antarctic are melting faster than before, up to over 1 m. a month in some areas. This phenomenon could increase the sea level by 5 m. The third is the increasing use and extraction of underground water, especially under big cities, which can make land surfaces sink due to loss of humidity (SIWRR, 2008). Coastal ecosystems (including mangrove forests) are highly vulnerable to Climate Change due to the social and economic pressure and its localization in coastlines. The mangrove ecosystem is expected to be the most affected, having a large economical and social impact (YÁÑEZ-ARANCIBIA et al, 1998; MCKEE et al, 2012).
ACID SULPHATE SOILS These soils are very common in most of the tropical and sub tropical coastal areas with a high presence in the Ca Mau peninsula. These are soils with a PH below 4 caused by oxidation of pyrite (Fe2S). The accumulation of this mineral is thanks to a combination of factors that occur only in tropical and sub tropical coastal areas. The sulphur of pyrite is derived from the sulphate in sea water, reduced biologically to sulphide in anaerobic mud. The ferrous iron (Fe2+) is derived from the reduction of insoluble ferric compounds from the weathering clay. Thereby, the combination of sulphate from sea water, organic matter from plant growth, the anaerobic conditions and the presence of ferrous iron gives as a result the formation and accumulation of pyrite in tropical coastal wetlands (ATTANANDANA et al, 1986). When pyrite accumulates remains in waterlogged soils, is called “potential” Acid Sulphate Soils (ASS), due to that they will only produce acidification when oxidised. When these soils become dry, the pyrite oxidises to form sulphuric acid (H2SO4) contaminating the water draining from it. But the main environmental impact comes from highly toxic level of aluminium and ferrous iron, which are also leached from ASS, being unavailable for plant uptake (with strong consequences for plant growth rates) and are toxic for the
aquatic ecosystem (BUCKTON et al, 1999).
THE LOCAL FLORA. MANGROVES What are the Mangroves? Mangroves are tidal forests commonly observed along found in sheltered estuaries and along river banks and lagoons in the tropics and subtropics. Situated between land and sea, the mangrove forest is host to some 69 species of plants called mangroves. These plants are adapted to lose wet soils, saline habitats (halophytes) and periodic tidal submergence (MARCHAND, 2008). The term ‘mangrove’ describes both the ecosystem and the plant families that have developed specialized adaptations to live in this tidal environment. The exact number of species is still under discussion and ranges from 50 to 70 according to different classifications (FAO, 2007). Mangroves are among the most important and productive systems in the world, providing food and nursery grounds for many commercially important aquatic and terrestrial animals; stabilizing coastlines and playing an important socio- economic role of the coastal dwellers (THI SAN et al, 1993). The competition for coastal land use and overexploitation have reduced or degraded mangrove coverage throughout much of their distribution, especially in South-east Asia. Although timber production was the initial motivation for early mangrove reforestation projects, benefits from protection against erosion and extreme weather events and direct improvements in livelihoods and food security have been perceived more recently as justifications for restoration efforts (WALTON et al, 2006). Growth and morphology Mangroves are easily distinguished by their root system, highly adapted to its habitat. The above- ground parts (pneumatophores) allows gas exchange with the below- ground parts. The growth rate varies among species, being the yield valuable timber the slowest. E.G., Bruguiera gymnorrhiza attains a height 7
Soils with saline properties > 6.4g/L
2.56g/L
Acid soils with saline properties > 6.4g/L
2.56g/L
Peat
2.5
Alluvial soils
10
25km
Acid Sulphate Soils- Saline Soils. From TRINH, 2013. KULeuven. Acid Sulphate Soils- aline Soils. From TRINH, 2013, KULeuven.
8
of 9-12 m and a girth of 23-30 cm in 15 years. In Thailand, Rhizophora species attain 14-18 m in height and 45-75 cm in girth in a period of 20-30 years (MARCHAND, 2008). Reproduction
Mangroves have no capacity for vegetative regeneration and no natural capacity for vegetative dispersal. Their dispersion and establishment at a distance are done by floating seeds or seedlings (propagules). All mangroves are dispersed by water, having
m Tre er Riv m Tre
Ri
Ca i
Ta u
er G Riv
On
g
anh
Do
c
ve r
Ri
ve r
Hao am
er D Riv i
Do
ap
er Riv
yH Ba
ua er C Riv
Mangrove > 70%
Melaleuca < 30%
Lon
SLR +65cm
Maximum annual average erosion distance in bank +70cm
10m
5m
3 - 5m
1 - 2m
0.5 - 1m
Current 2013,KULeuven. KULeuven. Currentgreen greenstructuresstructures-River River erosion. erosion .From From TRINH, TRINH, 2013.
9
the propagule some initial ability to float recognized by the mound of fresh mud up to (MARCHAND, 2008). 75 centimetres high around their entrances. These burrowing activities help to mix the soils Physiology and to change their surface characteristics. (MARCHAND, 2008). Against the common sense, mangroves are not very fond of saline water, being this a Importance of Mangrove Ecosystem physiological stress factor. These plants have developed several mechanisms to cope with Mangrove forests are an important coastal this stress, being a competitive advantage resource. A vast majority of human over other plants; having the ability to population lives in coastal areas, being obtain freshwater required for physiological source of highly valued products and fisheries processes from the pore-water surrounding resources (KATHIRESAN, 2013b). Although the absorbing roots. A little amount of salt coastal communities and scientists have is taken up by the tree and will accumulate, recognized the value of mangroves, policy excreting it via leaf glands, roots glands or makers and the general community have not by loose of parts; mainly leaves. Salt in high recognized the variety of services and offered concentrations is plant tissues is toxic and by mangrove forests. This mean that these must be largely excluded (MARCHAND, 2008). forests are competing for space with more â&#x20AC;&#x2DC;profitableâ&#x20AC;&#x2122; uses as urbanization, agriculture Biological Environment and aquaculture, as well as the over exploitation of forestry products and changes As said before, Mangroves are found in inter in water quality; resulting in worldwide losses tidal wetlands. This ecology has not structural of approximately 33% by area in 50 years analogues at higher latitudes, where salt especially in the south east of Asia (WALTON marshes occupy similar environmental et al, 2006). conditions. It seems to be a clear pattern among mangrove seedlings when they settle. Economic benefits: Mangroves supply Propagules of a certain species are specialised forests and fishery products. Due to the in colonising particular environments (pioneer high calorific values, mangrove wood is used species). Grazing is also a common feature in to make charcoal and firewood. This wood mangrove forests. Mangrove foliage is grazed has high content of tannin, making durable by cattle, sheep, goats, camels, isopods and timber. These trees attract honey bees crabs. The latest are important in reworking facilitating apiculture activities in some areas, the sediments among the mangroves. Mud producing high quality honey according with lobsters (Thalassia anomala) build large the mangrove species. Avicennia species tunnelling burrows which are generally Country South of Vietnam
Item of value Protection against extreme weather events
Cost (US$/ha/year)
Author, year
5000
Tri et al, 1998
Global
Forestry and fisheries benefits
500- 2500
Constanza et al, 1997
Idem Idem Idem Idem Idem Idem
Disturbance regulation Waste tratement Habitat Food production Raw materials Recreation
1839 6696 169 466 162 658
Idem Idem Idem Idem Idem Idem
Estimates values of mangroves. Adapted from KATHIRESAN, 2013b.
10
are a cheap and nutritive feed for grazing mammals, very common in India, Pakistan and Indonesia. Mangrove extracts are used in indigenous medicine in all places where they exist, having a potential for human, animal and plants pathogens (KATHIRESAN, 2013b). Mangroves can also provide seeds for aquaculture industries. WALTON et al (2006) in their studio of the socioeconomic impacts of a communityled reforestation project in the Philippines suggest that fish production related to replanted mangrove was 578–2568 kg ha/yr (US$ 463–2215 ha/yr), which can equal that of brackish-water aquaculture ponds. The replanted mangrove also supplied additional services providing an income from tourism of US$ 41 ha/yr and from sustainablyharvested timber of US$ 60 ha/yr. Therefore the total direct economic benefits from the replanted mangroves was US$ 564–2316 ha/yr depending on what percentage of the coastal and shoreline catches of mangrove associated species were attributable to the replanted mangrove (10–80%) (WALTON et al, 2006). See Annex Why Mangroves?
of life and property. They have an important role with the attenuation of oceanic waves as well as windbreakers (MARCHAND, 2008; KATHIRESAN, 2013b). The capacity of flood controlling of mangroves is due to the physical configuration of their root system and their ability to promote sedimentation, catching the sediments by inhibiting tidal flows due to the friction with the root system. The particles are carried to the mangroves from the sea water by the arriving tide and left behind and settling during low tide, most likely because the turbulence and water velocity is reduced and being able to catch about 80% of the sediments resulting in a rise of the substrate from 0.1 cm/year (FURUKAWA et al, 1997) to 0.8 cm/year (KATHIRESAN, 2013b). At the same time, mangroves can catch about 28% of the riverine fine sediment inflow. The sediment trapping efficiency of mangroves is a function of tidal dynamics in the mangrove wetlands, depending mainly of the complexities involved in the exchange process between mangroves and the closer coastal areas (KATHIRESAN, 2013b; VICTOR, 2004). This process can vary related with the different types of forest, Ecological services: Mangroves possess riverine, basin and fringe types. The process mechanisms to deal with intense sunlight falls in decreasing order: Riverine- basinrays and solar UV‐B radiation. Their foliage fringe. The river dominated system gets produces flavonoids2 that serve as UV‐screen allochthonous sediment supply, and the compound. These forests fix greater amount quantity of sediments deposited is a function of CO2 per unit area than phytoplankton of the catchments size. The fringe system, do in tropical oceans (KATHIRESAN, 2013b). as is tide dominated, contains abundant CEBRAIN (2002) estimated that a loss of about allochthonous sediments, being disturbed 35% of the total population of mangroves by tides. Beside this, mangroves control the in the world has resulted in a net loss of entrance of salt water to the inland and protect 3.8 x 1014g C stored as mangrove biomass. Mangroves also can form a shelterbelt against cyclones and storms, which has generated awareness among the local communities of the importance of this forest as protectors 2 Flavonoid refers to Organic compound, any member of a class of biological pigments containing no nitrogen that are found in many plants. They include anthoxanthins, which give yellow colours to flower petals and anthocyanins, responsible for the red colouring of buds and young shoots and the Importance of Mangrove ecosystem. From Kathiresan, 2003, 2012. purple and purple-red colours of autumn lea- Mecanisms of sedimentation induced by mangroves. From KATHIRESAN, 2003, 2012. ves. (Encyclopædia Britannica, 2013). 11
the underground water system (KATHIRESAN, 2013b). The sediments present in mangrove areas have the capacity to retain nutrients, recycling carbon, nitrogen and sulphur; being one of the few biotic systems that recycle sulphur efficiently in nature. These forests also have the capacity to absorb large amounts of pollutants, being feasible to use constructed mangrove wetlands as a secondary treatment process for municipal wastewater (WU et al, 2008; KATHIRESAN, 2013b) and to absorb and hold heavy metals. The oxygen exuded by the underground supports the formation of iron plaques in the root surfaces, avoiding metals to enter to the root cells. These metals are precipitated in the form of stable metals sulphides under anoxic conditions. Metals like Mercury (Hg) that cannot form sulphides are immobilized in organic complexes in the
sediments (KATHIRESAN, 2013b). The main importance of the mangrove forest to the adjacent marine ecosystem is through the export of dead organic material, motivating a complex foodweb (MARCHAND, 2008; KATHIRESAN, 2013b). The detached parts of the mangrove plants are decomposed by micro organisms when fall on the floor. In this process nutrients are released which enrich the surrounding waters. This decomposed organic matter along with microbial biomass is an important product of the mangrove ecosystems, serving as a nutritious food for a variety of organisms. The influx of nutrients generated by the mangroves supports many other sensitive habitats (KATHIRESAN, 2013b). For every hectare of forest cleared, nearby coastal fisheries lose approximately 480 kg of fish per year (MacKinnon and MacKinnon, Mangrove Litter Fall
Leaching of Nutrients
C rab C onsumption
D ecomposition
Land Run-O ff
N utrient R etention
D issolved Nutrients
Phytoplankton
Microbial Biomass
Nutrient R egeneration
Sea G rass
: Epiphytes
Faeces/D eath
Benthic Algae
Particulate matter & Sedim ent
Land Run-O ff
Small Invertebrates
D etritus
Larvae & Juveniles of Fin & Shell Fishes
Im migration of Larvae
Phytoplankton Based Material
Em igration of Sub-Adults
Adult prawns/ Fishes in O ffshore
Foodweb scheme in a mangrove ecosystem. From KATHIRESAN and BINGHAM, 2001 in A food web in a mangrove ecosystem. From Kathiresan and Bingham, 2001 in Kathiresan 2012. KATHIRESAN 2012.
12
Country/ area
Most recent reliable estimate ha
Ref. year
1980
1990
ha
ha
Annual change 1980–1990 ha
%
Annual change 1990–2000
ha
100
1992
150
1995
428 000
460 000
Brunei Darussalam
18 418
1996
18 400
18 400
0
0
18 400
0
Cambodia
72 835
1997
91 200
82 400
–880
–1.0
73 600
–880
China
22 480
2001
34 157
28 344
–581
–1.8
22 955
–539
India
446 100
2003
506 700
467 000
–3 970
–0.8
448 200
–1 880
Indonesia
3 062 30
2003
4 200 000 3 500 000
–70 000
–1.8
3 150 000
19 234
1997
27 500
22 500
800
2005
800
800
Japan Kuwait Malaysia
–500
90 476 000
–2.0
0
19 100
0
5
2004
n.s.
n.s.
n/a
n/a
n.s.
2005
674 000
642 000
–3 200
–0.5
589 500
n.a. a.
n.a.
n.a.
n.a.
Myanmar
518 646
1999
555 500
536 100
n/a
n/a
–1 940
–0.3
–1 1 600
–35 000 –340
n.a. 516 700
n/a
n/a –1 940
%
90
0
0
476 000
0
0
18 400
0
0
69 200
–880
–1.2
–2.1
22 480
–95
–0.4
–0.4
448 000
–40
n.s.
2 900 000
–50 000
–1.6
19 000
–20
–0.1
800
0
0
–1.1
–1.0 –1.6 0 n/a –0.8 n/a –0.4
n/a
n/a
–4 900
–0.8
n.a.
n/a
n/a
507 000
–1 940
–0.4
1995
2000
2 000
0
2001
345 000
207 000
–13 800
–5.0
158 000
–4 900
–2.7
Philippines
247 362
2003
295 000
273 000
–2 200
–0.8
250 000
–2 300
–0.9
500
199
0
0
500
0
0
500
0
0
20 000
–100
–0.5
20 000
0
0
20 000
0
0
Saudi Arabia Singapore
20 400
1985
21 000
–6.7
5 565 000
1 088
50
–100
ha
158 000
50
1000
0
Annual change 2000–2005
Pakistan
Qatar
0
–1.0
0
–5 250
2005 ha
0.3
800
564 971
Maldives
Oman
–4 0.7
%
476 215
Iran, Islamic Republic of
–5 3 200
ha
Bangladesh
Bahrain
10
2000
500
1990
1790
50
–129
–12.0
500
0
Sri Lanka
9 530
1996
9 600
9 30
–30
–0.3
9 000
–30
–0.3
Thailand
244 085
2000
280 000
250 200
–2 980
–1.1
244 100
–610
1 802
2000
4250
3 000
–125
–3.4
1 800
–120
Timor-Leste United Arab Emirates Viet Nam Yemen
Asia
0
1 000
0
0
157 000
–200
–0.1
240 000
–2 000
–0.8
500
0
0
8 800
–40
–0.4
–0.2
240 000
–82
–0.3
–5.0
1 800
0
0
4 000
1999
3500
3 800
30
0.8
4 000
20
0.5
4 100
20
0.5
157 500
2000
269 150
213 500
–5 565
–2.3
157 500
–5 600
–3.0
157 000
–100
–0.1
900
0
927
1993
6 047 798
2002
–5
–0.5
900
7 769 197 6 741 394 –102 780
1000
95
–1.41
6 162 645
–5 –57 875
–0.5 –0.89
5 857 575 –61 014
0 –1.01
Note: n.a. = not available; n/a = not applicable; n.s. = not significant.
Status FAO,FAO, 2007. Statusand andtrends trendsin in mangrove mangrove areas. area – From Asia. From 2007.
1986 in FAO, 2007) and the average yield of fish and shellfish in mangrove areas is about 90 kg per hectare, with maximum yield of up to 225 kg per hectare (FAO, 2007). Mangroves in Vietnam The mangrove ecosystem in Vietnam has varied through time, by one hand due mainly to the two Indochina wars and in particular with the use of herbicides and napalm during the Vietnam War (1962- 1971). This resulted in the destruction of nearly 40% of the mangrove forest in the south of Vietnam. There are listed at least 27 species of mangrove in the whole country (FAO, 2007).
By the other hand, mangroves has been exploited for their resources or replaced by agricultural or aqua cultural uses, being the main causes of loss of mangrove area due to conversion to other uses such as shrimp ponds, agriculture, salt pans and human settlements. Although Vietnam has only the 2.68% of total mangrove area in Asia (157000 ha in 2000), it has been presenting negative rates of loss of area since 1990´s3 (FAO, 2007). Apart of the effects of human activities, mangroves are susceptible to changes in 3 Due to the fact that reliable data about mangrove coverage is only available since 1990´s.
13
climatic, edaphic and hydrological conditions. distribution and extension of mangroves (THI The differences created by geographical SAN et al, 1993). conditions are also important; the consequences of these factors determine the The government of Vietnam signed in
CLIMATIC FACTORS
Temperature
Typical responses of mangrove to decreasing temperatures and increasing thermal amplitudes are reductions in the number of species and height and size of trees.
Rainfall
Rain regulates salt concentration and is an extra source of fresh water, favouring their physiological processes. As southwest monsoons from Indian Ocean bring heavy rains during summer, most dense mangrove forest can be found in Ca Mau cape (2000- 2200 mm/year with 120- 150 rainy days/year.
Winds
The northeast monsoons from East Sea (December- April) cause heavy erosion along the coast from Vung Tau to Ca Mau cape, affecting the growth of mangroves.
Tides
HIDROLOGICAL FACTORS
Ocean currents
The coast of Ca Mau receives mixed semi diurnal and diurnal tides. The last is less favourable for the growth of mangrove due to the double period of inundation that requires high storage of oxygen in the roots and the longer period of exposure to sunlight that causes evapotranspiration. Hence, in Ca Mau areas mangroves develop much better than those in the north thanks to the soil richness. Larger tidal amplitudes minimize seed and sediments settlement. Mangrove seeds are transported into Vietnam mainly by currents under the influence of winds from the Indian Ocean (Monsoons). These surface sea currents during the southwest and east monsoons (June to November) change their direction at latitude 12, causing the different species compositions between north and south of Vietnam.
Bring necessary nutrients and alluvium and dilutes the salt Fresh water currents water creating brackish water. It´s unusual for mangrove to grow in places of lacking fresh water. Salinity
Mangroves grow well in places like Ca Mau Cape where the salt concentration is moderate, about 22- 26 ppt.
Coastal erosion
A sea level rise can accelerate coastal erosion. Strong waves can deposit sediment in mangroves areas, covering pneumatophores and killing the trees.
Soils of mangrove areas are formed by alluvium from rivers and sediments from the sea. Mangroves survive on difSOILS ferent waterlogged and anaerobic substrate but they grow best in silt clay soils. Mangroves develop in shallow and calmed waters. Along the coast of the central part of Vietnam there are almost no TOPOGRAPHY mangroves due to the coastline is uneven and unprotected from the wave action. Factors affecting the mangrove distribution in Vietnam. Adapted from THI SAN et al, 1993.
14
Associated effects of mangrove From SANDILYAN et al, 2012.loss. From Sandilyan et al, 2012. Schematic diagram showingloose. concomitant effects of mangrove
1989 the Ramsar Convention on Wetlands, protecting 84982 ha in five designated sites. One of these sites is the Mui Ca Mau National Park, in the southern tip of the peninsula.
THE LOCAL FLORA. MELALEUCA
the Florida everglades in USA. The showy part of the tree is the flower, being the stamens the most notorious part of it. This “flower” is really an inflorescence formed by a cluster of small flowers (ANPSA, 2013). Reproduction
After flowering, melaleucas produce seed capsules that remain within it indefinitely, being easily collected at any time. This species Melaleuca is a genus of plants of around 170 have capacity for vegetative regeneration, species in the Myrtle family (Myrtaceae). being easy to propagate (ANPSA, 2013). The majority of species are endemic from Australia, but several occur more in the north Biological Environment (Indonesia, Vietnam, Malaysia, etc,). The melaleuca trees are commonly known as Melaleucas are found along watercourses or “paperbacks”, “honey myrtles” or “tea tree”. along the edges of non tidal wetlands near (ANPSA, 2013). coastal areas. They can grow in temporarily inundated with fresh water areas for up to Growth and morphology three to six months of the year and in arid regions. They are able to adapt to almost all Melaleuca are plants of open forest, woodland regions of hot climate with average monthly or shrubland, very popular for gardens and temperatures ranging from 23C to 270C. landscaping in several parts of the world. Due They also grow in areas of cold climate with to this, Melaleuca quinquenervia (a large tree winters of relatively low average monthly from Australia) has become a serious pest in temperatures of 13C (QUANG TRUNG, 2009). 15 What is the Melaleuca?
These forests provide a valuable nesting or roosting sites for a number of bats and birds and being an important food source for migratory birds. (THO HUNG, 2012). Importance of Melaleuca Ecosystem
this habitat. Due to this, forest composition is much simple in comparison with other forest ecosystem as mangroves (VU TAN, 2011). Small posts and poles are the historical main products from melaleuca, but the price of these products are very unstable, dropping from 15000 to 11000 VND per pole in the period from 2003 to 2006. Fluctuations are result of declining markets, lack of long term policies, planning, low product quality and inadequate risk management. Traditionally, plantation of melaleuca is practiced at very high stockings (10000 stems/ha or greater) to produce great numbers of small size posts and poles for general construction purpose (THO HUNG, 2012) and poor management; giving as a result irregular qualities in the wood. Decline is also associated with the change of land use to agriculture; to rice fields mainly (SIMPSON, 2009; THO HUNG, 2012). As said before, these forests are naturally adapted to grow in Acidic Sulphate Soils, in which other types of yields have lower productions than in optimal conditions (BUCKTON et al, 1999).
Melaleuca forests are particularly well adapted to difficult edaphic environment as inundating Acid Sulphate Soils. These forests play an important role in filtering the water that flows through them, catching it during rainy season and releasing it during dry season (THO HUNG, 2012; SIMPSON, 2009). Very few species have a commercial use. The timber of Melaleuca leucadendra and Melaleuca quinquenervia has been used as fence posts, railway sleepers, etc.; being also useful in honey production. Melaleuca alternifolia is also used for Tea Tree Oil, being the most significant use for this family. This oil is valuable as germicide and used in several beauty products (ANPSA, 2013). Its wood is very resistant to wet and muddy conditions (VAN CUONG, 2012) and there´s some existing evidence pointing that melaleuca can act as an ameliorative mechanism in Acid Sulphate Soil areas, reducing the levels of toxic aluminium STRATEGIC PROJECT. TAMING THE WATER and iron ions in the water in which it is grown As exposed before, the Ca Mau peninsula (BUCKTON et al, 1999). is facing several challenges due to different Melaleuca in Vietnam physical, natural, climatic and social variables. The following pages are related to one Melaleuca forests in the Ca Mau are a unique strategic project which looks for undertaking ecosystem that once covered extensive some of the described situations in order to areas of the peninsula, being the Melaleuca reshape the current landscape into a more cajaputi the most common native species resilient one. in south of Vietnam (VAN CUONG, 2012). Over the years as a result of the unplanned Taming the Water is about planting a natural use of fire, warfare activities, increasing dike along the coastline and in highly population pressures, etc., these forests eroded points of rivers with the use of have been reduced in extent and diversity local flora and local material as melaleuca (SIMPSON, 2009). It can be considered like a wood with two different models of fences. multipurpose species, being capable to adapt These were originally developed by the to diverse ecological zones (QUANG TRUNG, Deutsche Gesellschaft fßr Internationale 2009). Melaleuca species in Vietnam has at Zusammenarbeit (GIZ) GmbH in a pilot project least 4 varieties as melaleuca population and in the Kien Giang Province in Vietnam, started communities that are distributed naturally on in 2010 (VAN CUONG, 2012). This strategy can acid soil in Mekong delta. As melaleuca forest help to deal with the expected sea level rise ecosystem established under typical alum and climatic oscillations and extremes in the inundated environment (Acid Sulphate Soils), water regime, the management of ASS areas, only some species could adapt and survive to mangrove and melaleuca reforestation, etc. 16
Background As stated earlier, mangroves play a key role in coastal protection against extreme natural and climatic conditions as typhoons, tsunamis, flooding, erosion protection, etc. The trees can reduce the height and velocity of incoming waves through the drag forces applied in their radicular system (KATHIRESAN, 2013b), being used as a shelterbelt along the coasts.
planting propagules, collected seedlings or cultivated seedlings that natural recruitment will not provide the quantity of successfully established seedlings (LEWIS et al, 2006). As said before, Melaleuca cajaputi is a native species that grows in the south of Vietnam; it used to be very common in the whole peninsula but with scarce presence at the present time in form of few patches, mainly as a forest reserve. This species has been used historically as a local construction material, but now is being displaced by the use of concrete. The drop in the demand along with
Forest restoration programs have been previously carried in Vietnam and all around the world, most attempts often failing completely or fail to achieve the main goals (LEWIS et al, 2006; MARCHAND, 2008). About Sediment trap fence 580 ha on the seaward side of the dyke in Ha 3 m = 40 pole size 4 Tinh province was planted with mangroves TYPE 1 4 4 4 4 4 4 4 4 4 4 4 between 1989 and 1993 in order to develop 3m a green barrier for coastal protection with survival rates around 40% (MARCHAND, 2008). From 2000 to 2010, the 661 program implemented in Kien Giang planted 500 ha approximately of new mangrove forest with single species (Avicennia alba or Rhizophora apiculata) with a survival rate of 50% ( DUKE et al, 2010 in VAN CUONG, 2012). These From VAN COUNG et al, 2012. break fence failures are often attributed to inappropriate Wave Seaward side species selection, inappropriate site selection (MARCHAND, 2008), poor quality seedlings 5 4 4 4 4 4 4 4 4 4 4 5 4 4 4 4 4 4 4 4 4 4 and lack of protection of seedlings from mechanical forces during the initial stages of growth after planting (VAN CUONG, 2012). 5 5 5 5 5 5 5 5 5 5 5 5 5 5 E.g., in the Philippines, the favoured but unsuitable Rhizophora ssp. is planted in sandy 5 substrates of the exposed coastline instead 4 of the natural pioneers Avicennia ssp. and Sonneratia ssp. Also with low survival rates (MARCHAND, 2008). According to LEWIS, 2006, Sediment trap fence Sediment trap fence in order to achieve a 3successful m = 40 pole size 4mangrove restoration, five main steps are necessary: TYPE 2 TYPE 1 3 m = 40 pole size 4 x 2 rows = 80 poles 4 4 4 4 4 4 (individual 4 4 4 4 4 autoecology 1. understand the 4 4 4 4 4 4 4 4 4 4 3m species ecology) of the mangrove species 4 4 4 4 4 4 4 4 4 4 naturally present in the site, 2. understand the normal (natural) hydrology patterns that 4 Melaleuca Pole 4 control the distribution and autoecology of the Fishing net mangrove species, 3. calculate modifications Bamboo mat of the original mangrove environment in Melaleuca support frame order to prevent secondary succession, 4. design the restoration program to restore the Fences From VAN COUNG, 2012. From VAN COUNG et al, 2012. From VAN design. COUNG et al, 2012. appropriate hydrology and 5. Utilize actual 3m
Sediment TYPE 2
From VAN COUNG
3m
3 m = 1 pole size 5 + 40 pole size 4
0.5 m
0.5 m
3 m = 18 pole size 5 pushed 2 m into mud
Melaleuca Pole 5 (diameter 8 cm) Melaleuca Pole 4 (diameter 5 cm) Melaleuca branches Fishing net
Bamboo mat
From VAN COUNG et al, 2012.
(diameter 5 cm)
17
others motives explained before have helped to reduce its market value.
normally, preventing smothering seedlings. This fence grants the right conditions for natural regeneration of mangrove forest and Characteristics is placed parallel to the coastline where the water depth in high tide is about 50 cm. It is The coastline defence is made of two different made with smaller melaleuca poles tan the types of fences made mainly of melaleuca wave break fence and bamboo. poles, with a less proportion of bamboo matting and fish netting; being able to reduce The riverline defence is made with the significantly the erosion and to increase the sediment trap type 2, working in the same height of the soil. The external fence is the way that the coastline defence, but with a Wave Break Fence, made of two rows of single fence placed in highly eroded spots in melaleuca poles and melaleuca branches in the rivers and canals. This fence is also made with middle that are able to move with the waves small melaleuca pole (as the sediment trap absorbing part of its energy. Normally, these type 1), bamboo and fish netting. Melaleuca branches are considered as residual wood, wood can endure between 10 to 15 years in being burned after the thinning. Every pole is wet and muddy conditions. By the time these 3 meters height and is pushed 2 meters into structures disappear, the soil will be naturally the mud. This external row is placed parallel to consolidated thanks to the root system of the the coast and where the water depth in high mangroves (VAN CUONG, 2012). tide is about 1 m, reducing the strength of the wave energy hitting to the shores assisting Behind of every fence different types of the stabilization of the coastline. The internal mangrove seedlings are planted, giving fence is the Sediment Trap type 1, designed priority to pioneer (colonizers) and dominant to trap the sediments deposited by the waves species according with the place where the (mainly in wet season) allowing to develop fence is built. Strategic planting can also enough structure to enable the root system of be done in order to increase populations seedling and seed anchor in the soil an grow of endangered or productive species. This YEAR 0
. min
2 m. min
2m
Seedling pioneer species
High tide
1 m. aprox.
Seedling secondary species
YEAR 1 20 cm/ year aprox.
High tide
YEAR 5
High tide
WAVE BREAK
SEDIMENT TRAP 1
Growing scheme.
18
Average Sediment Accumulation per Treatment (m) over 1 year
0.3
Wet season SW Monsoon
Dry season NE Monsoon
0.25 0.2
Sep 2011
Aug 2011
Jul 2011
Jun 2011
May 2011
Apr 2011
-0.1
Feb 2011
-0.05
Mar 2011
0 Jan 2011
Wave Break + Trap Fence
0.05
Dec 2010
Control
0.1
Nov 2010
Accumulation (m)
0.15
Date
Sediment elevation over time. Adapted from VAN COUNG, 2012. Sediment elevation over time. From VAN CUONG, 2012. 70 9 8
60 50
6 40 2
5 4
Individuals/m
Number of species
7
3 2
20 10
1 0
30
Natural Mangrove
Control
Wave break + Sediment trap
Crustacea
0 Natural Mangrove
Control
Wave break + Sediment trap
Bivalvia Gastropoda
Species density. Adapted from VAN COUNG, Species diversity. Adapted from VAN COUNG,Species density. 2012. From VAN CUONG, 2012. 2012.
Species diversity. From VAN CUONG, 2012.
system allows animals to move freely in and out of the involved areas, getting close at the benthos4 diversity and density found in natural mangroves areas. The planted seedlings have a survival rate at around 82% in the coastline defence and 57% in the riverline defence, being higher than most of the former reforestation attempts.
capable to produce the high amount of wood needed. In Ca Mau, there is already 170 km of coastline without any defence more than the existing mangrove forest that need to be protected from the sea level rise. Taking as a base the available information referred to the eucalyptus planting (a related species from the same family, Myrtaceae) which has already a wood industry developed worldwide and due The catching rate of sediments makes the soil to the lack of information found referred to grow at a rate of 20 cm/year, turning about a melaleuca planting, it can be assumed that natural growing dyke. with an industrialized production of melaleuca can be produced 2500 poles/ha with a This system utilizes a massive amount of harvest every 8 years (KFS, 2009). In 1 linear melaleuca wood. With the present low yields Km of coastal protection (wave break fence and irregular management in melaleuca and sediment trap type 1) is needed 32340 plantings, is not possible to develop an industry melaleuca poles of 3 different diameters, 4 Benthos is referred to the assemblage resulting in a planting average of 12.93 ha per each linear Km of coastal protection. Due to of organisms inhabiting the seafloor. (Encythe fact that for the complete construction clopĂŚdia Britannica, 2013). 19
YEAR 5
Tidal Level: 3- 3,5 m
EXISTING MANGROVES
CANAL
Rhizophora apiculata (P) + Ceriops decandra 25
100
EAST SEA
Sediment trap 1
Avicennia alba (P) + Rhizophora apiculata + Avicennia officinalis
Wave break
200 M
elevation. Current and scenario the 5th year of the project. YEAR 5 EastEast coast coast elevation. Current condition andcondition development in year 5 of the in project.
Tidal Level: 0,8- 1,2 m
Tidal Level
Wave break 25
YEAR 5
100
Avicennia alba (D) + Avicennia officinalis
Sediment trap Type 1
DYKE
EXISTING MANGROVES
GULF OF THAILAND
Rhizophora mucronata (D) + Bruguiera sexangula
200 M
West coast coast elevation. Current condition and development in 5th in year of the West elevation. Current condition and scenario the 5thproject. year of the project.
Sulfuric horizon 50- 70 cm
Tidal level
Avicennia alba (P) + Avicennia alba (P) + Avicennia officinalis Avicennia alba (P) Avicennia officinalis
Sediment trap 2
EXISTING MANGROVES
25
Sediment trap 2
GANH HAO RIVER
100
Sulfuric horizon 70- 100 cm Avicennia alba (P) Avicennia alba (P) + Avicennia officinalis Avicennia alba (P)
EXISTING MANGROVES
200 M
Gan Hao River elevation. Current condition and scenario in the 5th year of the project.
of the required coastline defence its needs the wood produced by 2199.12 ha in just one harvest, a progressive silvicultural project must be established in order to provide enough material for the construction of the defence.
is compared with the different expected sea level rise scenarios, by the ending of the coastal defence construction around the whole Ca Mau peninsula (2056) becomes evident that the growing soil can compete with the sea level rise..
The proposed scenario shows 4 different plots (two with 150 ha and two with 200 ha) planted every one with 2 years of each other and with the 8th year of the first planting the beginning of the construction of the coastal defence. In this scenario the whole coastline protection can be finished 34 years later than the first planting, harvesting every 2 years from different plots using them over and over again.
With the construction of the coastal defence can be developed several silvicultural projects in places where the presence of ASS is a problem, due to the release of toxic metals and acidification of water. At the same time, availability of fresh water must be considered due to the fact that with the climate change, industrial planting should have plenty availability of fresh water for not to depend on rainy seasons.
If the same scenario exposed previously The phasing construction of the coastal (starting to plant in 2017 and to build in 2025) protection can provide a stable market for 20
CANAL
DYKE
Planted Area (ha) 200 175 150 125 100 75 50 25 Years 2
20
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40 60 80 100 120 140 160
170 Km
180 Dike construction (Km)
Planting/ harvesting/ building proposed scenario. Planting- harvestingbuilding proposed scenario. Global mean sea level rise (cm above 1992) 120
2056 (consolidation)
2091
1,2 m 1m
80 0,5 m 40 Observed scenarios
0,2 m
0
-40 1900
Year 1950
2000
2050 2025 (construction begining)
2100
2051 (construction ending)
Proposed scenario and Sea LEvel Rise. Adapted from NOAA, 2012. Proposed scenario and sea level rise. Adapted from “Global Sea Level Rise Scenarios for the United States National Climate Assessment”, NOAA, 2012.
the melaleuca wood for many years, giving enough time to acquire the “know how” of the industry and the appropriation of technology to be able to compete in local and international markets. Expected Response to Sea Level Rise Although some authors argue that increments in sea level between 12 and 27 cm every 100 years can make collapse mangrove ecosystems, there are strong evidences showing that these won´t be affected with rises between 50 and 80 cm every 100 years. During the last half decade, mangroves in Key West, Florida have been expanding into the sea and inlands, in spite of yearly hurricanes and a sea level rise of 23 cm every 100 years (YÁÑEZ-ARANCIBIA et al, 1998). Analysis of stratigraphy and chronology of Holocene deposits on coastal shorelines have been
used to prove that mangrove shorelines have persisted under sea level rise rates about 1015 mm/year (MCKEE et al, 2012). The response of a combined system as Ca Mau mangrove forest (river-dominated/ influenced, wavedominated/ influenced, tidedominated/ influenced) largely depends of the sediment supply and catchment deposited in growing areas. Sedimentation budgets equal to sea level rise may enable intertidal areas to remain relatively stable (SIWRR, 2008; MCKEE et al, 2012). This confirms that tidal inundation is the main factor in species zoning regarding with sea level rise. Different mangrove species, without presence of important physical barriers can be able to migrate into inlands making possible a redistribution of species along the forest thanks to the different tolerances and autoecologies of mangrove 21
20
10
Proposed plots for silvicultural project.
10
Proposed plots for melaleuca planting.
species. According with Kirwan et al, 2010 resilience of this coastal protection will be (in MCKEE et al, 2012) “wetland resilience increased, providing the natural conditions to may be exhausted under rates of sea-level allow a “natural” grow of the defence. rise of only a few millimetres per year when suspended sediment concentrations are low, while wetlands may match sea-level rise of several centimetres per year when suspended sediment concentrations are high. Only those wetlands with tidal ranges exceeding 3 m and high suspended sediment concentrations may survive rates exceeding 20 mm/year…” This indicates that mangrove forest in Ca Mau peninsula can be able to deal with the expected sea level rise without any other intervention, being the mangrove forest in Possible mangrove response to Searesponse Level Rise. From to Hashimoto, in SIWRR, 2008. mangrove Sea 2001 Level Risse. the east coast the more resilient. With the Possible From HASHIMOTO, 2001 in SIWRR, 2008. construction of the coastal defence, the 22
CONCLUSIONS
ANPSA- Australian Native Plants Society. Web http://asgap.org.au/melaleuc.html in June 12 2013.
The result of this project is a strategy to cope with the sea level rise at a peninsula scale, providing a resilient living coastal protection ATTANANDANA, Tasnee, VACHAROTAYAN, Sorathat act like a soft dyke and provides the sith, “Acid Sulfate Soils: Their Characteristics, Genesis, Amelioration and Utilization”, in Southeast following qualities: Asian Studies, Vol. 24, No.2, 1986.
• The coastal protection is built with local and easily available materials, non specialized labour and is much cheaper than the normal hard dyke systems.
BINH, T.N.K.D., VROMANT, Nico, THANH HUNG, Nguyen, HENS, Luc, BOON, E.K, “Land Cover Changes between 1968 and 2003 in Cai Nuoc, Ca Mau Peninsula, Vietnam”, in Environment, Development and Sustainability, Vol. 7, pp. 519–536, 2005.
• Produces minimal disturbance to the tidal systems, allowing to mangrove BUCKTON, Sebastian T., CU, Nguyen, DUC TU, Nguyen, QUYNH, Ha Quy, “The Conservation of forest to develop “naturally”. • Enhances and requalifies the existing green structures along coasts and rivers, increasing the economical and ecological services that mangrove forests can offer, as the relation with the benthic fauna and the cleaning water functions among others. • Gives a feasible productive alternative with the Acidic Sulphate Soils (ASS) promoting the change from low productivity farming to a more suitable production, allowing trapping toxic metals and alleviating the effects into the environment. • Provides a stable market for this new productive alternative (melaleuca wood) giving time during the construction of the coastal protection to get the “know how” of the industry in order to make it competitive at international spheres.
Key Wetland Sites in the Mekong Delta”, Conservation Report Number 12, BirdLife International, Royal Netherlands Embassy, 1999.
Ca Mau website. “Cong Thong Tin Dien Tu. Tinh Ca Mau.” Web http://www.camau.gov.vn/ in June 5 2013. CEBRAIN, J., “Variability and control of carbon consumption, export, and accumulation in marine communities” in Limnology and Oceanography, Vol. 47, pp. 11‐22, 2002. COULTHART, Alan, QUANG, Nguyen, SHARPE, Henry, “Urban Development Strategy. Meeting the challenges of rapid urbanization and the transition to a market oriented economy”, 2006. Web http://siteresources.worldbank.org/INTEAPINFRASTRUCT/Resources/Urban.pdf in May 12 2013. Encyclopædia Britannica, “Encyclopædia Britannica Online Academic Edition”, Encyclopædia Britannica Inc., 2013. Web June 09 2013. FAO Forestry Paper, “The World´s Mangroves. 1980- 2005”, Vol. 153, 2007.
• Gives an alternative to diversify FURUKAWA, K., WOLANSKI, E., MUELLER, H., the aquaculture related economy, “Currents and Sediment Transport in Mangrove introducing another economic activity. Forests”, in Estuarine, Coastal and Shelf Science The coastal protection can be a progressive and feasible alternative that can deal with some of the most important challenges that the Ca Mau region is facing. The role of the government (local and central) is crucial to give the necessary conditions that can allow start the strategy.
Vol. 44, pp. 301–310, 1997. HENS, Luc, VROMANT, Nico, THO, Nguyen, HUNG, Nguyen Thanh, “Salination of surface water, groundwater, and soils in the shrimp farming areas of the coastal Cai Nuoc district, South Vietnam”, in International Journal of Environmental Studies, Vol. 66, No. 1, pp. 69–81, 2009.
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HONG, Hiep Le, “Performance-based Legitimacy: The Case of the Communist Party of Vietnam and Doi Moi”, in Contemporary Southeast Asia Vol. 34, No. 2, pp. 145-172, 2012. IPCC, INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE, “Climate Change 2007- Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel of Climate Change.” Cambridge, 2007. Web http://www.ipcc.ch/publications_and_data/ar4/wg2/en/contents.html in June 5 2013. KATHIRESAN, K., “Policy and Sustainable Management Strategies: Restoration Technologies.” UNUOpenCourseWare, Web www.ocw.unu.edu in March 19 2013a. KATHIRESAN, K., “Importance of Mangrove Ecosystem”. UNUOpenCourseWare, Web www.ocw. unu.edu in March 19 2013b. KENYA FOREST SERVICE- KFS, “A Guide to On-Farm Eucalyptus”, 2009. LEBEL, Louis, HOANG TRI, Nguyen, SAENGNOREE, Amnuay, PASONG, Suparb, BUATAMA, Urasa, THOA, Le Kim, “Industrial Transformation and Shrimp Aquaculture in Thailand and Vietnam: Pathways to Ecological, Social, and Economic Sustainability?” in Ambio 31(4), pp. 311-323, 2002. LEWIS, R.R., BROWN, Ben; QUARTO, “Five Steps to Successful Ecological Restoration of Mangroves”, Alfredo, ENRIGHT, Jim, CORETS, Elaine, PRIMAVERA, Jurgenne, RAVISHANKAR, T., DEIVA STANLEY, Oswin, DJAMALUDDIN, Rignolda (Ed.), Mangrove Action Project, Yayasan Akar Rumput Laut, 2006. MCKEE, Karen, ROGERS, Kerrylee, SAINTILAN, Neil, Response of Salt Marsh and Mangrove Wetlands to Changes in Atmospheric CO 2 , Climate, and Sea Level” in Global Change and the Function and Distribution of Wetlands, MIDDLETON, Beth A. (Ed.), Springer Science+Business Media Dordrecht, pp. 63- 96, 2012.
guide”, WRU/ TUD, Deltares, 2008. MINH, L.Q., TUONG, T.P., VAN MENSVOORT, M.E.F., BOUMA J., “Contamination of surface water as affected by land use in acid sulphate soils in the Mekong River Delta, Vietnam”, in Agriculture, Ecosystems and Environment 61, pp. 19-27, 1997. Ministry of Natural Resources and Environment. Sub-Institute of Hydrometeorology and Environment of South Vietnam, “Climate Change in the Mekong Delta. Climate scenarios, sea level rise, other effects”, Vietnam-Netherlands Mekong Delta Masterplan project, 2010. Web http:// www.partnersvoorwater.nl/wp-content/uploads/2011/06/CLIMATE-CHANGE-final-draft.pdf in June 5 2013. PHAM Thi Anh , KROEZE, Carolien, BUSH, Simon R., MOL, Arthur P.J., “Water pollution by intensive brackish shrimp farming in south-east Vietnam: Causes and options for control”, in Agricultural Water Management 97, pp. 872–882, 2010. QUANG TRIEU, Hay, “Bank Erosion Processes along the Lower Mekong River”, PhD thesis, University of Southampton, Faculty of Social and Human Sciences, Geography and Environment, 2012. QUANG TRUNG, Nguyen, “Melaleuca Timber- Resource potential and its current use in Kien Giang Province”, Deutsche Gesellschaft fuer Technische Zusammenarbeit (GTZ) GmbH, 2009. RENAUD, Fabrice G, KUENZER, Claudia (Ed.), “The Mekong Delta System. Interdisciplinary Analyses of a River Delta”, Springer Science+Business Media Dordrecht, 2012. SANDILYAN S., KATHIRESAN, K., “Mangrove conservation: a global perspective” in Biodiversity and Conservation, 2012. SIMPSON, John, “Improving Production and Income to Farmers from Melaleuca”, Deutsche Gesellschaft fuer Technische Zusammenarbeit (GTZ) GmbH, 2009.
MACKAY, Peter, RUSSELL, Michael, “Socialist Republic of Viet Nam: Climate Change Impact and Adaptation Study in the Mekong Delta”, Vietnam Institute of Meteorology, Hydrology and Environment (IMHEN) and the Ca Mau Peoples Committee, 2011.
SIWRR- Southern Institute for Water Resources Planning, “Climate Change Scenarios. Assessment for Ca Mau Province. Technical Report”, 2008. Web http://awsassets.panda.org/downloads/ vietnam_full_final_report.pdf in May 2 2013.
MARCHAND, Marcel, “Mangrove restoration in Vietnam. Key considerations and a practical
THI SAN, Hoang, HONG, Phan Nguyen, “Mangroves of Vietnam”IUCN, 1993.
24
THO HUNG, Ngo, “District Based Climate Change Assessment and Adaptation Measure for Agriculture in Ca Mau, Vietnam”, Institute of Meteorology, Hydrology and Environment, Hanoi, Vietnam, APEC Climate Center, 2012. TRI, Vo Khac, “Hydrology and Hydraulic Infrastructure Systems in the Mekong Delta, Vietnam”, in RENAUD, Fabrice G., KUENZER, Claudia, (Ed.) “The Mekong Delta System. Interdisciplinary Analyses of a River Delta”, Springer Environmental Science and Engineering, 2012. United Nations Human Settlements Programme (Un HABITAT), United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP), “Housing the poor in Asian cities, Urbanization: The role the poor play in urban development”, Nairobi: United Nations Human Settlements Programme, Vol. 1, 2008. Web http://www.unhabitat.org/pmss/listItemDetails.aspx?publicationID=2526 in April 4 2013. United Nations, “World Urbanization Prospects: The 2011 Revision”. Web http://esa.un.org/unup in June 5, 2013.
World Bank. Web http://data.worldbank.org in June 5 2013. WU, Y., CHUNG, A., TAM, N.F.Y., PI, N., WONG, M.H., “Constructed mangrove wetland as secondary treatment system for municipal wastewater”, in Ecological Engineering Vol. 34, pp. 137–146, 2008. XUE, Zuo, LIU, J. Paul, DEMASTER, Dave, NGUYEN, Lap Van, OANHTA, Thi Kim, “Late Holocene Evolution of the Mekong Subaqueous Delta, Southern Vietnam”, in Marine Geology 269, pp. 46–60, 2010. YAMASHITA, Shota, TAMURA, Toru, SAITO, Yoshiki, NGUYEN, V. Lap, OANH, T.K. Ta, BATEMAN, Mark D, MATSUMOTO, Dan, “Origin and evolution of Interdistributary delta plains; insights from Mekong River delta” in Geology Vol. 40 No. 4, pp. 303–306, 2012. YÁÑEZ-ARANCIBIA, Alejandro, TWILLEY, Robert R., LARA-DOMÍNGUEZ, Ana Laura, “Los Ecosistemas de Manglar Frente al Cambio Climático Global”, in Madera y Bosques 4(2), pp. 3-19, 1998.
UNVERRICHT, Daniel, SZCZUCIŃSKI, Witold, STATTEGGER, JAGODZIŃSKI, Karl Robert, THUYEN LE, Xuan, WEE KWONG, Laval Liong, “Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam”, in Global and Planetary Change, 2013. Web http://dx.doi. org/10.1016/j.gloplacha.2012.12.009 VAN CUONG, Chu, BROWN, Sharon (Ed.), “Coastal Rehabilitation and Mangrove Restoration using Melaleuca Fences. Practical Experience from Kien Giang Province”, Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, 2012. VICTOR, S., GOLBUU, Y., WOLANSKI, E., RICHMOND, R.H., “Fine sediment trapping in two mangrove-fringed estuaries exposed to contrasting land-use intensity, Palau, Micronesia”, in Wetlands Ecology and Management Vol. 12, pp. 277–283, 2004. VU TAN, Phuong (Ed.), “Forest Ecological Stratification in Vietnam”, RCFEE, UN REED, FAO, 2011. WALTON, Mark, SAMONTE-TAN, Giselle, PRIMAVERA, Jurgenne, EDWARDS-JONES, Gareth and LE VAY, Lewis, “Are Mangroves worth replanting? The direct economic benefits of a community based reforestation project” in Environmental Conservation Vol. 33 (4), 2006.
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Annex 1. WHY MANGROVES?
Annex WHY MANGROVES? Fodder, timbers and pulpwood. 1 ha
Direct beneficts
Rhizophoraceae ssp.
Tannins, medicines, adhesives, etc. 1 ha
Local fauna habitat and production.
Manis javanica
1 ha
13,3 t/year
Natural tannin (no market)
7740 Kg/ year
90- 225 Kg/year
Cyprinidae ssp.
Herpestes javanicus Crocodylus porosus
Prionailurus bengalensis Varanus salvator
Pseudibis gigantea (locally extinted)
Mycteria cinerea (locally extinted)
Pantera tigris (locally extinted)
Bubalus arnee (locally extinted)
And many, many others...
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Rhizophoraceae ssp. Co2
Co2
CO2 storage. C burial rate= 580 g/m2/year
Ecological beneficts Land forming and conservation. 0,1- 0,8 cm/ year Expected sea level rise: 0,6- 0,8 cm/year
Water cleaning. 1 ha
0,5- 0,3 ha farming
Protective beneficts Wind breaking.
10 m
2 Km/h 50 Km/h
0,25 m
Wave attenuation. 30 trees/ 100 m2 15 cm
3m
1,5 m
100 Km/ h
50 Km/ h 200 m
Sources: WALTON, Mark, SAMONTE-TAN, Giselle, PRIMAVERA, Jurgenne, EDWARDS-JONES, Gareth and LE VAY, Lewis, “Are Mangroves worth replanting?. The direct economic benefits of a community based reforestation project.” Environmental Conservation 33 (4), 2006. MARCHAND, Marcel, “Mangrove restoration in Vietnam. Key considerations and a practical guide”, WRU/ TUD, Deltares, 2008. FAO Forestry Paper, “The World´s Mangroves. 1980- 2005”, 153, 2007. KATHIRESAN, K., “Policy and Sustainable Management Strategies: Restoration Technologies.” UNU OpenCourseWare, www.ocw.unu.edu, accesed in 19/03/2013. KATHIRESAN, K., “ Importance of Mangrove Ecosystem”. UNU OpenCourseWare, www.ocw.unu.edu, accesed in 19/03/2013.
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Annex 2. MANGROVES OF OFOF VIETNAM MANGROVES OF THE THESOUTH SOUTH VIETNAM ACANTHACEAE Acanthus ebracteatus
Loam, clay soil. normal or equinoctial tides.
ACANTHACEAE
Acanthus ilicifolius normal or equinoctial tides. Natural regeneration. Protection of lagoons and estuaries.
AIZOCEAE
Sesuvium portulacastrum
Firm mud or wet sandy mud. tial tides.
ARCEAE
Cryptocoryne ciliata
Loam soil under S. caseolaris or Nypa canopy. normal or equinoctial tides.
AVICENNIACEAE Avicennia
alba
Deep mud.
PI ON Protection of lagoons Eandseaestuaries. Dyke protection alongE Rand aquaculture farms. all high tides.
AVICENNIACEAE
Avicennia lanata
Sandy mud.
PI ON E
normal high tides.
ER
AVICENNIACEAE
Avicennia marina
all high and spring tides.
PI ON lagoons and estuaries. E Natural regeneration.
Coastal protection and protection of Harvest of forest products. sources AVICENNIACEAE
ER
Dyke protection along sea and aquaculture farms.
Loam clay and degraded soils.
PI ON Protection of lagoons EEand estuaries. Coastal and dyke protection R along andspring tides.
Greening of barren coasts. Natural regeneration.
sea and aquaculture farms. Harvest of forest products.
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BIGNONIACEAE Dolichandrone
spathacea
Loam clay. or equinoctial tides.
COMBRETACEAE Lumnitzetra
littorea or equinoctial tides.
COMBRETACEAE
Lumnitzetra racemosa or equinoctial tides.
EUPHORBIACEAE
Excoecaria agallocha or equinoctial tides. Natural regeneration. Dyke protection along sea and aquaculture farms.
MELIACEAE
Xylocarpus granatum
mal high and normal or equinoctial tides. Harvest of forest products.
MELIACEAE Xylocarpus
moluccensis
Clay. or equinoctial tides.
MYRSINACEAE
Aegiceras corniculatum
Wet sandy, sandy mud. high and spring tides. Natural regeneration.
PALMAE
Nypa fructicans
normal or equinoctial tides.
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PALMAE
Phoenix paludosa
soil. noctial tides.
PTERIDACEAE
Acrotichum aureum
Firm mud, in clearings. normal or equinoctial tides.
RHIZOPHORACEAE
Brugiera gymnorrhiza
Loam, sandy mud, foot of limes-
Harvest of forest products. resources. RHIZOPHORACEAE Brugiera
PI ON spring tides. E tone.
H2S
cylindrica
ER
Dyke protection along sea and aquaculture farms.
Restoration of mining areas. Firm mud.
PI ON Protection of lagoons EEand estuaries. Restoration of mining areas. R spring tides.
H2S RHIZOPHORACEAE
PI ON areas. Restoration of mining EE R normal high tides.
RHIZOPHORACEAE Brugiera
sexangula
H2S
Loam.
PI ON areas. Restoration of mining EE R spring tides.
RHIZOPHORACEAE Ceriops
decandra
H2S
Firm mud.
PI ON Restoration of mining EEareas. R normal or equinoctial tides.
H2S RHIZOPHORACEAE
Ceriops tagal
Firm mud under Rhizo canopy.
PI ON Dyke protection along E sea and aquaculture farms. ER spring tides.
Harvest of forest products.
H2S
Greening of barren coasts.
Restoration of mining areas.
30
RHIZOPHORACEAE Kandelia
candel
Loam, sandy mud.
Restoration of mining areas.
PI ONagainst tidal Coastal protection EE waters, erosion and cyclones. R Protection of lagoons and estua-
Harvest of forest products.
ries.
spring tides.
RHIZOPHORACEAE Rhizhophora
apiculata
H2S
PI ONcyclones. waters, erosion and EE estuaProtection of lagoons and R ries. Dyke protection along sea and medium high and spring tides.
Coastal protection against tidal
H2S
Harvest of forest products.
Restoration of mining areas. RHIZOPHORACEAE Rhizhophora
mucronata
H2S
Harvest of forest products.
Restoration of mining areas. RHIZOPHORACEAE Rhizhophora
stylosa
aquaculture farms.
PI ON E
equinoctial tides. Coastal protection against tidal waters, erosion and cyclones. Protection of lagoons and estuaries. Dyke protection along sea and
ER
aquaculture farms.
PI ON Protection of lagoons E and estuaries. Dyke protection alongEsea and R aquaculture farms. spring tides.
H2S
Restoration of mining areas.
RUBIACEAE
Schyphiphora hydrophyllacea
Sandy mud. or equinoctial tides.
SONNERATIACEAE
Sonneratia alba
mal high tides. Coastal protection against tidal waters, erosion and cyclones. Harvest of forest products.
SONNERATIACEAE Sonneratia
caseolaris
mal or equinoctial tides. Protection of lagoons and estuaries. Dyke protection along sea and aquaculture farms.
SONNERATIACEAE
Sonneratia ovata or equinoctial tides.
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STERCULACEAE
Heritiera litoralis
Sandy loam. or equinoctial tides.
PIONEER: Pioneer species.
H2S: Acidophilus species.
Bibliography: KATHISERAN, K. “Policy and Sustainable Management of Mangroves. Conservation and Management Strategies: Restoration Technologies”, UNU OpenCourseWare, www.ocw. unu.edu in 19/03/2013. NGUYEN HONG, Phan, THI SAN, Hoang. “Mangroves of Vietnam”, IUCN, 1993. www.iucnredlist.org, in 04/05/2013.
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