The relevance of COP 21 to endangered South American wildlife

Summary

  • The aim of the UN COP 21 meeting held in Paris at the end of 2015 was to negotiate a global agreement on reducing greenhouse gas emissions to limit global temperature increases
  • The negotiated “Paris Agreement” formally recognised forests as being of key importance
  • It is hoped this recognition will slow deforestation and habitat loss and help preserve endangered wildlife species in the Amazon

Introduction – what was COP 21?

The 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP 21) was held in Paris from 30 November to 11 December 2015. Its aim was to negotiate a global agreement between the 196 parties in attendance to reduce greenhouse gas emissions in order to limit global temperature increases. Following lengthy negotiations, a new international agreement on climate change was reached to strengthen the global response to climate change by “…Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels…”. All attending parties signed up to this agreement, referred to as the “Paris Agreement” [1].

However, halting global temperature rise at 2°C will require significant effort from all nation states, and not just through reducing fossil fuel emissions, but also by better managing sinks of CO2 such as forests which absorb huge amounts of CO2 and keep it stored. Deforestation through agricultural expansion, ranching, infrastructure projects, energy exploration and illegal logging all release this stored CO2 back into the atmosphere, whilst also decreasing the overall sink capacity.

What conclusion did COP 21 reach regarding deforestation?

Programmes to reduce emissions from deforestation have existing for some time, for example the United Nations’ Reducing Emissions from Deforestation and Forest Degradation (REDD) programme which launched in 2008, and which aims to place a financial value for the carbon stored in forests by offering incentives for developing countries to reduce emissions from forested lands. The follow up REDD+ programme expanded upon this concept, to include the role of conservation, sustainable management of forests and enhancement of forest carbon stocks, with key stakeholders and programme developers being the indigenous peoples of the forests [2].

The Paris Agreement comes back to this REDD+ concept, and Article 5 is focused on slowing deforestation and forest degradation, by encouraging that “Parties should take action to conserve and enhance, as appropriate, sinks and reservoirs of greenhouse gases… including forests”. During COP 21, a number of governments (including Colombia, Germany, Norway and the UK) pledged to continue their financial support for projects such as REDD+ to continue to reduce deforestation and forest degradation through results-based payments [3].

How does this relate to endangered species in South America?

Deforestation of the Amazon rainforest is causing habitat loss to countless animal species. If pursued, the vision set out in the Paris Agreement could help sustain at risk populations in the Amazon such as the jaguar, macaw, poison dart frog and black spider monkey [4]. As of 9th May 2016, 176 states and the European Union have signed the Agreement. 16 of those states have ratified the Agreement, but it has not yet entered into force [5].

References

[1] https://unfccc.int/resource/docs/2015/cop21/eng/l09r01.pdf

[2] Global Forest Resources Assessment 2010 – Food and Agriculture Organization (FAO) of the United Nations Forestry Paper. Available from http://www.fao.org/docrep/013/i1757e/i1757e.pdf

[3] http://www.worldbank.org/en/news/feature/2015/12/18/outcomes-from-cop21-forests-as-a-key-climate-and-development-solution

[4] http://www.worldwildlife.org/places/amazon

[5] https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XXVII-7-d&chapter=27&lang=en

Trouble in paradise: Oil roads significantly reduce rainforest frog biodiversity

Summary:

  • The canopy of tropical rainforests harbour a rich variety of life, and remain a largely unexplored scientific frontier
  • Bromeliads are plants that grow in the rainforest canopy, and their leaves form minute ponds in which water can collect, playing host to many other species
  • Disturbance caused by road building and deforestation dramatically alters these complex arboreal ecosystems, with strongly negative impacts on biodiversity

There is an entire world in microcosm living among the branches in the rainforest canopy. This world is complex and replete with microhabitats, hence it supports many thousands of species. The canopy is largely unexplored by scientists, due in part to the difficulties of conducting a study tens of metres above the ground. One of the most important microhabitats present in the lofty world among the trees are phyotelmata- miniature pools that form in the leaves of plants that are perfectly adapted to life in the tree tops. And the most important of these plants are the bromeliads- they have specialised ‘tanks’ at their base, where overlapping leaves form a leak-proof pond of water in order to trap water. This is because most bromeliads are epiphytes- plants that live on tree branches whose roots never touch the ground, relying on airborne mist and dust for their water and nutrition.

Ranitomeya variabilis male, carrying his tadpole on his back. [Picture retrieved from http://www.dendrobates.org/images/variabilis_nominal9.jpg 17/02/2016]
Many animal species are bromeliad specialists; they can live and breed nowhere else. Among the most common specialists are frogs- they require water to hatch their eggs and rear their tadpoles- and as such they are at the greatest risk should anything happen to their arboreal nurseries. One such species is the fantastically colourful poison dart frog Ranitomeya variabilis (left): only as large as your thumbnail, potently poisonous and brilliantly adapted to the rainforest high-life. The female of this bijou little frog lays her eggs in the tank of a bromeliad, and supplies it with infertile eggs as food. Should anything endanger the tadpole, the male carries it on his back to find safety in a new bromeliad pond.

Yasuní national park, in the Ecuadorian Amazon, is the most biodiverse place on Earth, and is a fantastic place to study the rainforest canopy as its variety of life is almost unmatched. Unfortunately Yasuní is under threat by recent oil exploration due to its underground reserves of fossil fuels. A recent study published in the online journal PLoS ONE has attempted to examine the damage caused by this exploration, with a focus on the impacts of oil road construction. The investigation focussed on the response of bromeliad-dwelling frog diversity under three different ‘treatments’- intact forest, low-impact road construction (which uses geofabric as a base) and high-impact road construction (which uses felled trees as a base).. Along with this they recorded environmental variables such as the tree species that bromeliads were living on, the height above the ground that they were growing and the number of bromeliads growing in each tree. The researchers focussed on frogs living in one particular species of pool-forming bromeliad, Aechmea zebrina. Their analyses revealed a startling result: bromeliads growing near oil roads (both low and high-impact) harboured significantly fewer individual frogs from fewer species. Deforestation has many effects on rainforests- the loss of large trees reduces the local

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Bromeliads (Aechmea zebrina) in Yasuni national park, with the author collecting specimens. Retrieved from McCracken & Forstner (2014)

humidity, increases temperature and further tree mortality. As well as this, toxic fumes from oil-towing vehicles could pollute the areas surrounding the road. Both bromeliads and frogs are ‘hypersensitive’ to changes in climatic conditions, because they rely on the moist, cool rainforest air to supply them with water and prevent them from drying out. This, coupled with the reduced number of bromeliads, drastically reduces the habitat space available to canopy-dwelling amphibians; habitat loss is one of the greatest threats to frogs worldwide.

Detrimental effects of oil extraction of tropical rainforests are well documented, and as this study shows even the lowest possible impacts of oil extraction have a significantly destructive influence on these mega-diverse systems. As such, the authors suggest that no further access routes are made into Yasuní, and best-practice methods are used to try to protect this precious tropical Eden.

 

 

Reference

McCracken, S.F., Forstner, M.R.J. (2014) ‘Oil road effects on the Anuran community of a high canopy tank bromeliad (Aechmea zebrina) in the Upper Amazon Basin, Ecuador’ PLoS ONE 9(1): e85470. doi:10.1371/journal.pone.0085470

Riverine roadblocks: Vital connections between Amazonian watercourses severed by environmental change

Summary:

  • The Amazon basin has the highest freshwater fish diversity in the world, and provides fish for millions of people along its course
  • The interconnected watercourses of the Amazon are in danger due to dam building and droughts caused by climate change
  • Conservation strategies have been devised based on ‘metapopulation theory’, where connectivity is maintained between the many thousands of watercourses in the Amazon basin
  • These strategies aim to protect fisheries and biodiversity by improving their resilience to change

The Amazon River and its tributaries are home to over 5600 fish species- more than the entire Atlantic Ocean. This plethora of species supports many millions of people living along the banks of the mighty river, who depend on fishing for subsistence and income. The forests, floodplains and lakes of the Amazon are interconnected during half of the year due to seasonal flooding, linking watercourses across a vast area; the river acts as the veins for the ‘lungs of the Earth’. The interconnected nature of these watercourses allows fish to move far and wide across the Amazon basin, causing the seasonal influx of many millions of fish, directly providing food for local people. In addition to this, flooding brings new individuals (and by extension, new genes) into the mix, allowing fish to breed and the next generation to disperse. Indeed, this connectivity is a key part of the life cycles of many economically (and ecologically) important fish species.

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The watercourses of the Amazon are many and linked by seasonal flooding

Unfortunately, these seasonal ‘fish highways’ are at risk. The most imminent threat comes from the building of hydroelectric dams. Dams act as an impenetrable barrier to fish that need to migrate along river systems in order to breed, preventing them from reaching their spawning grounds. The second major threat to the aquatic life of tropical floodplains is climate change, which also acts as a road block for these fish thoroughfares. Climate change extends the dry season, trapping fish in ever-shrinking water bodies, severing the connections between aquatic environments and reducing the influx of food that is usual
ly washed in by floods. These problems will only become more severe in the coming decades, as development encroaches on wilderness, and the climate continues to warm. The reduction in recruitment of young fish due to hampered seasonal flooding will also lead to a reduction in fish stocks, increasing their vulnerability to overexploitation by humans.

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Many species are dependent on Amazonian wetlands, such as the 3m wide Victoria water lily.

A recent study published in Biological Conservation highlights the importance of habitat connectivity to Neotropical fish communities, the threats they face and most importantly suggests conservation strategies aimed at preserving the interconnected nature of Amazonian floodplains. The conservation strategies are based ‘metapopulation theory’- the way that natural populations hedge their bets against environmental change. It posits that in nature organisms exist in metapopulations- small, inter-connected populations that individuals may freely disperse between. Under this pattern, should any natural catastrophe locally wipe out a metapopulation, there will always be a source of new individuals from one of the others able to recolonise. This hugely reduces the likelihood that an entire species will go extinct. Since dam construction is an immediate threat to the connections between metapopulations and to the breeding patterns of many migratory species, Hurd et al. suggest that governments should slow the rate of damn construction on these important watercourses, and where construction must take place that ‘fish ladders’ (artificial steps allowing fish to migrate up and down river) should be built.

Climate change and its effects on the floodplains of the Amazon is an altogether more difficult problem to address. However, the authors promote the establishment of large protected areas in order to encapsulate as much biodiversity as possible, and to facilitate the regulatory functions that intact ecosystems undertake. In addition to this, reducing overexploitation of fish species by banning commercial fishing, only allowing subsistence catches under a quota system would allow fish metapopulations to replenish stocks naturally. These community-based management techniques have been shown to work in the Madre de Dios region of the Peruvian Amazon, and can hopefully be applied across the Amazon basin.

 

References:

Hurd, L.E., Sousa, R.G.C., Siqueira-Souza, F.K., Cooper, G.J., Kahn, J.R., Freitas, C.E.C. (2016) Amazonian floodplain fish communities: Habitat connectivity and conservation in a rapidly deteriorating environment. Biological Conservation 195: 118-127

Environmental change and the extinction of ecological interactions

Summary:

  • Interactions between species allow ecosystems to function, and channel energy, nutrients, water and other resources. 
  • A new mathematical model was devised to test whether the loss of species and the loss of ecological interactions were connected.
  • Where ‘keystone’ interactions are removed, a cascade of other ecological interactions are lost, even before other species become extinct
  • Climate change and habitat loss sever ecological links between species, disrupting the function of ecosystems and reducing the benefits they provide.

“When we try to pick out anything by itself, we find it hitched to everything else in the Universe”. These were the words of John Muir, the famous twentieth century naturalist and one of the first proponents of the conservation movement. It implies that when one element of a natural system is changed there will be a cascade of effects upon all of its constituents; this is an astute observation as ‘ecological cascades’ – changes to one small part of an ecosystem having a disproportionately large effect- are well demonstrated in environmental science. If these interactions are so complex and far- reaching, then how will they change life on Earth in the face of species extinction and climatic change?

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Interactions between species are complex and interlinked, like the threads of a spiders web

A recent study by Alfonso Valiente-Banuet et al. may have the answer. Using a new type of mathematical model that takes into account the diversity of species, the diversity of their interactions and the degree of environmental degradation, the group investigated whether there is a link between species extinction and loss of ecological interactions.

The importance of species interactions may at first be unclear, but they are essential for the functioning of living systems. A healthy ecosystem is a web of interconnected organisms, all performing different roles and chaperoning the cycling of energy and nutrients- the unintentional product of this cycling is the provision of ecosystem services which directly benefit us. For example, think of how trees take groundwater and through transpiration turn it into rain clouds, or of the constant recycling performed by earthworms in your allotment, returning nutrients to the soil so that you can grow those prize-winning pumpkins. On a large scale and under major environmental devastation the loss of some interactions may have far more dire consequences- droughts, famine and increased susceptibility to natural disasters to name a few (Diaz et al., 2006).

In the face of environmental change, these links become more and more threatened as the species that orchestrate them go extinct, eliminating key elements of the web. The study, published in Functional Ecology, shows that with increasing environmental degradation the rate of the loss of ecological links depends on the species in question. Generalist species, species that are ecological ‘jack-of all trades’, have interactions that are easily replaced by other species in the ecosystem until most species are extinct. However, many of the most important ecological jobs are conducted by ‘keystone’ species, which demonstrate ‘keystone’ interactions- i.e. those that have a disproportionately large effect on the ecosystem, and whose loss would mean the loss of many critically important interactions. It is these species that have the strongest effect on the extinction of ecological interactions, even before many other species go extinct. These are the interactions which should be conservation priorities, as ‘…to ensure the long-term provision of ecosystem services that depend upon biodiversity, the greatest attention should be focused on those components of biodiversity, such as species interactions, that can be affected by the new scenarios emerging in a changing world. ‘

 

References:

Díaz S, Fargione J, Chapin FS III, Tilman D (2006) Biodiversity Loss Threatens Human Well-Being. PLoS Biol 4(8): e277. doi:10.1371/journal.pbio.0040277

Valiente-Banuet, A., Aizen, M.A., Alcántara, J.M., Arroyo, J., Cocucci, A., Galetti, M., García, M.B., García, D., Gómez, J.M., Jordano, P., Medel, R., Navarro, L., Obeso, J.R., Ovideo, R., Ramírez, N., Rey, P.J., Traveset, A., Verdú, M., Zamora, R. (2015) ‘Beyond species loss: the extinction of ecological interactions in a changing world’. Functional Ecology 29: 299-307.