Dr Sophie Fauset, Lecturer in Environmental Science at the University of Plymouth, explains her recent research into the leaf temperatures of China's tropical forests and how this relates to climate change.
Tropical forests in a changing climate
My research is looking at how tropical forests might respond to climate change and human impact.
Limestone forest at Xishuangbanna Tropical Botanic Garden
Researching in the treetops
"The research that I’ve been doing in China is measuring leaf temperatures of different tree species in the tropical forest because we don't actually have much data about this. Leaf temperatures are not necessarily the same as the air temperature because the leaf is affected by how much light it is receiving and the amount of transpiration that occurs (as the evaporating water cools it down)."I spent two months at the Xishuangbanna Tropical Botanic Garden in China, where they have many research stations with canopy cranes. These canopy cranes are amazing because they allow you to go to the top of any tree that you want within reach of the crane. It solves what is often one of the main challenges of this fieldwork which is actually getting access to the leaves!”
"Once we were up there, we attached tiny sensors to the leaf surface which are then connected to a data logger. This records measurements continuously so you can see how temperature fluctuates throughout the day. This allows us to build up a picture of leaf temperatures in different species of trees and from that we can think about what impact climate change might have on these forests.
"We often think of trees as being along a spectrum. At one end there are the pioneer species which will be the first that colonise an environment and these trees tend to grow quite fast. Then on the other end, you get the shade tolerant species which can grow under the shade of a full canopy and tend to grow slower. As the fast-growing pioneer species are trying to capture a lot of light, they have quite big leaves but also quite high levels of transpiration meaning the leaves stay cooler."
Measuring leaf temperatures of Parashorea chinensis
Temperate montane forest, Jade Dragon Field Station
The potential impact of climate change
"I’m still working on the data at the moment so it’s uncertain what the findings will be but my hypothesis is that the slower growing trees, which have the hotter leaf temperatures, are probably going to struggle more in the face of increasing atmospheric temperatures. Whereas the faster growing trees have quite high transpiration, making it easier for them to stay cool.
"In terms of consequences, climate change could affect the species composition of the forest depending on which species can tolerate rising air temperatures. If I’m correct that this will map onto the fast growing versus slow growing spectrum, you could potentially get a reduction in the carbon stock of the forest if it becomes more dominated by the pioneer species. Faster growing species tend to store less carbon because their wood is less dense, whereas slow growing species store carbon over a longer time."
From the canopy to the classroom
"It’s brilliant getting to go out and work in the field to collect new data like this and it also allows me to incorporate what I've learnt into my teaching.
"I teach students about tropical forest ecology in a third year module 'Biological Conservation', but even when I'm teaching broader first year modules I try to include examples of my own work when we discuss topics such as species composition.
“I also really enjoying getting students out in the forest to collect their own data. We have a fieldtrip to Malaysia where students get the opportunity to do their own tropical forest research project. I find it very rewarding to share my skills and enthusiasm for fieldwork with them.”