Notes from the Nursery

An integrated approach

Matthew Nicholson, volunteer editor, Notes from the Nursery

I am a member of the nursery team in a botanic garden and also work as a bush restorer. Please get in touch if you would like to contribute to this section in the future by emailing me at nicholson20@hotmail.com.au.

The roles of botanic gardens as agents of change and influence are manifold, from instituting environmental education programs for schools all the way to the brass tacks of controlling where seed is sourced and leading the way in experimental horticulture and environmental management. Botanic gardens have in recent decades undergone a necessary reinvention as institutions of environmental governance. In this capacity, they contribute worldwide to the preservation of species that have been declared extinct in the wild due to conditions such as urbanisation, pollution and global warming due to climate change. Rather than dwell at length upon our sins with respect to this, I will concentrate on the positives that various institutions, governmental policies, and individuals have had on climate change research, with examples from various academic sources. Regardless of one’s views on climate change, the very fact that it is being discussed at governmental and non-governmental levels is indicative of the amount of concern the notion has engendered since the discovery of the hole in the ozone layer 40 years ago. This discovery led to the Montreal Protocol (1987), which sought to combat the ozone depletion caused by humanity’s use of CFCs, and was ‘the only UN treaty ever ratified by all 197 UN Member states’ (Reuters Fact Check, 2022). During the Industrial Revolution (1760–1840) rapid urbanisation occurred in many parts of the world, and changes to farming due to population shift became evident in terms of the number of people that swelled the cities. A direct result of this population shift was the number of horses providing transport on the streets of London and in other major cities around the globe. The horses produced an astronomical amount of manure, contributing to diseases like typhoid fever and cholera running rife in urbanised areas. In 1894 The Times reported that ‘in 50 years every street in London will be buried under nine feet of manure’. Thus, environmental measures were put into place, such as the sewage system and, ironically, the internal combustion engine. In terms of global government legislation, the aftermath of the Great Smog of 1952 in the United Kingdom precipitated the Clean Air Act 1956, which restricted the burning of coal in domestic fires as well as in industrial furnaces.

Initially, a combination of electric vehicles and internal combustion engines was seen on the streets of New York and London, but thanks to the capitalism that flourished during and after the Industrial Revolution, wealthy industrialists like Henry Ford saw more benefit in championing the internal combustion engine, which powered the motor car, or ‘the horseless carriage’. These measures were arguably reasonable in the short term – they rectified the problems caused by horses, but no-one was even dimly aware of the long-term repercussions for the greater environment that carbon monoxide would create – a problem in a similar vein to the Great London Smog caused by coal fires in people’s homes and from furnaces.

Botanic gardens host several resources to aid with the task of addressing climate change. Some of these include herbaria, which provide collection waypoints and may help to chart any changes to the geographic range of a specific genus or species, provided the records extend back far enough; ‘research at botanical gardens has advanced our understanding of climate change impacts’ (Primack et al., 2021). Primack et al. (2021) cite several examples of how researchers have used resources at botanic gardens to examine changes to plants’ anatomy and phylogeny as they adapt to climate change, thereby easing the process of prioritisation for conservation. Many plants are unable to adapt quickly enough and simply die out. The tragedy is that a great many species have already gone extinct before they are even discovered by Western science and conserved in ex situ collections. Various plants, however, demonstrate the ability to adapt or to acclimate their morphology and physiology to changing environments (phenotypic plasticity). Species with greater phenotypic plasticity will have an advantage over those more narrowly adapted; for example, Holm Oak Quercus ilex seedlings close their stomata when exposed to drought (Gimeno et al., 2009).

Various plants demonstrate the ability to adapt or to acclimate their morphology and physiology to changing environments.

Other research at botanic gardens includes whether gene flow facilitates responses to climate change in terms of an ‘adaptive response’ (Anderson and Song, 2020) and evaluating whether climate change exerts unique selection, and in this exertion is disruptive of local adaptation, changing species interaction (Aguirre-Ligouri et al., 2019).

From an ethical perspective, to restore plant ecosystems globally the number of wild seeds needed is into the ‘hundreds of thousands’ (Neville et al., 2018) but overharvesting by seed collectors risks depleting seed banks unless the seeds can be ethically sourced. There is an industry standard when undertaking seed collection operations; best practice is to collect no more than 10% of an individual or population’s seed production in one season. There are several good reasons for this. First, to refresh the natural seed bank to allow for regeneration and genetic diversity – this diversity is further supplemented by the efforts of local regeneration (both Bushcare and Landcare) groups and contractors in cooperation with residents and city councils. Other reasons include ensuring that seed collectors collect sustainably – the guidelines are in place to guarantee that collectors aren’t removing more seed from individual plants than is required for the collectors’ purposes.

Several years ago, I went on a guided tour of the University of Western Sydney (UWS) with the Australian Institute of Horticulture. We were taken to their research facility for a ‘walk and talk’, which included a tour of the Whole Tree Chambers containing specialised instruments measuring water use and rate of photosynthesis. The species they were researching was Parramatta Red Gum Eucalyptus parramattensis and its response to climate change – hence the need for atmospheric chambers. The temperature in the chambers was raised 3 °C above the average temperature in the Sydney region. The trees grew to more than 6 m in 12 months. Researchers then increased the temperature inside the chambers to 43 °C for four days; the second stage in the process demonstrating the remarkable resilience of this species to contend with severe prolonged temperate changes. The results were truly remarkable and are explained in more detail here.

In addition to the Whole Tree Chambers, plots of eucalyptus woodland were selected on which were installed a series of pipes. CO2 was funnelled through these pipes for a series of experiments on CO2 enrichment. This Eucalyptus Free-Air CO2 Enrichment facility (EucFACE) at UWS is the first in the world to study the effects of higher concentrations of CO2 in native forests. The research suggests that under elevated CO2, extra photosynthate is produced, transported below ground and respired, and, perhaps surprisingly, not used for extra growth (Drake et al., 2016; Jiang et al., 2020).

Whole tree chamber at UWS.

Credit: Matthew Nicholson.

In recent decades, botanic gardens have broadened their scope to include discussion of, and research on, the effects of climate change on native plant populations. They have sought to reinvent themselves as transmitters of this knowledge in education and programs for schools; for example, interpretive signage, public engagement (such as workshops) and using significant occasions such as BGANZ’s Botanic Gardens Day to highlight the role botanic gardens play in climate change education. Due to the expansive global network of botanic gardens, the resulting impact of this public engagement has been exponential.

Some gardens possess extensive herbaria, which enable long-term tracking of ecological change over periods of global change. These valuable, and scarce, long-term datasets are used by climate-change scientists to provide ‘windows into the past’ (Lang et al., 2019) and help plan the management and mitigation of climate change into the future. So, using several layers of information – herbaria, government legislation, and collation of industry best practice – botanic gardens can (and are):

• disseminating information to assist with the collation of climate change and habitat dislocation caused by climate change

• providing the public with information concerning the challenges posed by climate change caused by pollution, habitat reduction/destruction, and by increased urbanisation – increased urbanisation means more concrete and open spaces, which in their turn increases heat signatures contributing to the warming of our cities and urban centres.

Urban heat islands can cause ‘thermal discomfort, higher energy consumption, and aggravated pollution effects’ (de Almeida et al., 2021), and botanic gardens have risen to the challenge of showcasing how the effects of these urban heat islands may be mitigated. Singapore has some prime examples of these mitigation measures in its showcasing of green walls and roof gardens. This is an exemplar of how this design style may be utilised to its greatest effect in an urban environment. Singaporeans did this in response to the problem of urban skyscrapers blocking sunlight to such an extent that no garden could grow. So, they used higher criticism to form a solution.

I believe one of the outstanding buildings in Singapore that includes a roof garden is the Kampung Admiralty, completed in 2017. In Australia, one of the standouts is the Sky Park and Gardens in Melbourne (designed by Nicholas Rivett for the Far East Corporation); the largest of its type in Australia. It won the inaugural Australian Institute of Horticulture’s Urban Green Space Award in 2017.

Botanic gardens (and the nursery industry in general) have an integral role to play in promoting ways in which we as communities can reduce urban heat islands and green our cities. There have been steps put in place by some local authorities to begin educating people on the vital importance of returning green spaces and vegetation to our urban and suburban landscapes. Botanic gardens can aid and assist research into climate change by sharing resources with scientists and sharing data with climatologists to be collated and rationalised. They can play a role in deciding which species are planted where in our landscape design schemes by working alongside town planners and landscape architects, providing horticultural input into species placement. By working together with these individuals, professional organisations, and government bodies, botanic gardens can be effective agents of change, and have an influence on both urban and suburban landscapes. We can utilise our broad horticultural knowledge base as an effective teaching tool to help effect that change in thinking.

Botanic gardens have an integral role to play in promoting ways in which we as communities can reduce urban heat islands and green our cities.

References

Anderson, J, & Song, B-H. (2020). Plant adaptation to climate change – where are we? Journal of Systematics and Evolution. 58(5):533−545.

Aguirre-Liguori, J, Ramírez-Barahona, S, Tiffin, P, et al. (2019). Climate change is predicted to disrupt patterns of local adaptation in wild and cultivated maize. Proc. R. Soc. B. 286:20190486.

de Almeida, C, Teodoro, A, & Gonçalves, A. (2021). Study of the Urban Heat Island (UHI) using remote sensing data/techniques: a systematic review. Environments, 8(10):105.

Drake J, Macdonald C, Tjoelker M, et al. (2016). Short-term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration. Glob Chang Biol. 22(1):380−90.

Gimeno, T, Pias, B, et al. (2008). Plasticity and stress tolerance override local adaptation in the responses of Mediterranean holm oak seedlings to drought and cold. Tree Physiology, 29(1):87−98.

Jiang, M, Medlyn, B, Drake, J et al. (2020). The fate of carbon in a mature forest under carbon dioxide enrichment. Nature 580, 227–231.

Lang P, Willems F, Scheepens J, et al. (2019). Using herbaria to study global environmental change. New Phytol. 221(1):110−122.

Neville, P, Cross, A, & Dixon, K. (2018). Ethical seed sourcing is a key issue in meeting global restoration targets. Current Biology, 28(24):R1378−79.

Primack, R, Ellwood, R, Gallinat, A, et al. (2021). The growing and vital role of botanical gardens in climate change research. New Phytologist, 231(3):917−932.

Reuters Fact Check. (2022, August 3). Fact Check-The ‘hole’ in the ozone layer was a real threat, but has been healing due to international action.