Everyone knows about the tropical forest biodiversity crisis. Agricultural conversion, logging and fire are pushing species ever closer to the precipice of extinction, while some have already plummeted over the edge. This destruction is also causing loss of carbon into the atmosphere, contributing to climate change, and changes the ecosystem services we get from these forests.
But you already knew all that, right?
What you may not know about is the Reducing Emissions from Deforestation and Degradation (REDD+) initiative (those of you who do know, feel free to skip ahead to the next paragraph). In short REDD+ is a policy championed by some that aims to reduce the potential emissions from forests, largely by paying communities that live in and around them to manage them sustainably. Of all the tools we could use to help reduce deforestation this policy has been the one to generate most hype over the last few years. I’ve lost count of the number of talks, debates and papers I’ve seen discussing it since I became a PhD student.
Though it seems like a generally good idea (and yes I know there are lots of caveats to this), there have been fears about its potential effects on biodiversity. There is the potential that only forests which have high carbon density would be prioritised, thereby missing out large areas with unique biodiversity. This seems stupid for a policy which targets forests, especially when these forests are home to so many unique species. Equally however, just concentrating on biodiversity might not catch areas with high carbon density.
It is here where a new(ish) paper by Chris Thomas in Ecology Letters comes in. The paper acknowledges the problems of focussing solely on one goal, and explores how you could balance the two most effectively.
To do this they used maps of carbon, along with maps of species ranges in both the Americas and UK. This is, in my opinion, a bit unrealistic since they perceive a world in which protection of carbon everywhere is considered of equal value – at the moment REDD+ is very much targeted at forests in developing countries. Nonetheless, this paper provides a few pointers on how to target this policy. Using the carbon and biodiversity maps they used the program Zonation to come up with areas considered priorities for carbon storage and biodiversity by selecting the 30% of cells with the greatest value.
Doing this for carbon solely realised peoples fears about poor protection for biodiversity. In the Americas protecting the 30% of land with highest carbon could protect nearly half the carbon stocks of the continents, but only 34% of bird biodiversity. Similarly in the UK prioritising carbon solely could protect 59% of carbon stocks, but only 25% of biodiversity.
The picture was similar when they targeted biodiversity only. In the Americas this would lead to protection of 71% of biodiversity, but only 30% of carbon. In the UK this would protect 93% of biodiversity but only 25% of carbon.
Both of these results clearly present a problem, targeting one goal does not automatically mean that you do particularly well with the other even if areas of high carbon tend to be in areas of high biodiversity.
The final analysis they did was to see how well the two goals could be achieved. By foregoing a loss of 10% of the maximum carbon in the America it was possible to maintain 91% of the maximal biodiversity value. The picture was similar in the UK where foregoing 10% of the maximum carbon meant it was possible to protect around 90% of biodiversity.
Given the previous concerns about targeting protection of carbon this paper seems remarkably positive. There seems no reason why, with careful and systematic planning, we can’t design policies to protect the two.
My criticisms of the paper still hold though, and it seems like a bit of an oversight that someone hasn’t done a similar analysis for countries which will realistically be part of REDD+ in the near future.
Having said that, we need to more analyses like this for more places – Africa and Asia, as well as Europe spring to mind, but we also need to get on and map and model ecosystem services other than carbon storage. This way we can get a better balance between managing the things we need to live and the biodiversity that underpins in. There is more to the benefits we get from ecosystems than just carbon