Right at the end of the extremely dry period we had this summer I decided to do a little experiment: I started taking a photo of the patch of grass in my street in Manchester, in the North West of England, every couple of days. I study the effects of drought on ecosystems (see my previous posts about the effects of drought belowground here and here) and I thought it would be nice to show how the grass in my street would bounce back after the rain had started.
Only… it didn’t. The rain did not come as intensely as I expected, and the grass did not bounce back as quickly as I expected. The first (top left) photo was taken on the 12thof July, the last (bottom right) on the 20thof August. And still you can see bare soil and brown patches! This patch of grass would look a lot lusher and greener during a normal Manchester summer.
The grass in my street in Manchester this summer.
But, more importantly, while aboveground plant growth seems mostly recovered, the composition of the community has changed (which you can’t see in these photos), and as I’ve shown in my research, this might continue to affect belowground communities and the processes they perform.
Of course, this little patch of grass in Manchester is not that important for the functioning of our ecosystems. But it is a nice illustration of the impacts of an extremely dry summer on grassland and how long it takes for these fast-growing plants to regain their biomass!
There has been plenty of media coverage of the current extremely hot and dry weather. The drought is revealing archaeological features, (see also here), and we can even see the browning of our landscape from space. But this drought is not good news for our ecosystems at all, and one example of that are the recent wildfires in the Peak District. These fires are not just bad news for the plants and animals that live there, but also they make large amounts of carbon that have been sequestered over many years go up in the air as CO2, and this can amplify climate change. Drought also affects our ecosystems more subtly than that, but the long-term consequences might be as severe.
We can all see the effect the drought is having on plants: lawns are turning yellow, corn leaves are rolling, and in extreme cases, trees even lose their leaves. They become inactive, and can even die. This is not just bad news for the plants, it is also bad news for the soil. When plants stop growing, they are not photosynthesing, and when they are not photosynthesising, they are not removing CO2from the atmosphere. A large part of this photosynthesised CO2 goes straight into the soil to fuel the activities of microbes, which carry out important functions such as the decomposition of plant litter and the release of nutrients for plant growth. Continue reading