ZSL conservation scientists lead ground-breaking research using satellites to understand the impacts of rewilding efforts over two decades, at famous UK site.
A long-standing UK rewilding project which has seen key species and native vegetation returned, has been monitored for the first time from space, showing remarkable ecosystem recovery.
Our scientists have used long-term satellite data to monitor and evaluate the impacts of more than 20 years of nature restoration efforts at the Knepp Estate in West Sussex – one of England’s longest running rewilding sites.
New research published today by ZSL’s Institute of Zoology, Imperial College London and the University of Sussex, gathered satellite data and imagery such as those available from Google Earth, to track changes in trees and shrubs from 2001 to 2020 across the 1,400-hectare Knepp Estate.
After scouring years of earth observation images across seasons, the team pieced together a picture of definitive nature recovery at the site, with results showing that rewilding efforts have led to a 40% increase in areas with trees, and six times more shrubs than before the project started.
The UK is one of the most nature depleted countries in the world, with only an estimated half of its original biodiversity left. Exponential rates of land use change for agriculture and urbanisation are the top drivers of this.
Following World War II, the Knepp Estate was used for intensive agriculture, but after this was deemed unprofitable, the owners turned it into a conservation site with selected areas open to the public. Since this time, the estate has become home to a diversity of returning wild species, including rare turtle doves (Streptopelia turtur), nightingales (Luscinia megarhynchos), peregrine falcons (Falco peregrinus) and purple emperor butterflies (Apatura iris).
Rewilding - the process of rebuilding a functioning and self-sustaining ecosystem by restoring natural processes and food webs - is increasingly seen as an important tool to help repair damage to natural systems, which are the foundations of all life on earth.
Satellite data showed that nature has bounced back particularly well in the south side of the Estate where fields were left for long periods before the introduction of herbivore species such as Exmoor ponies and fallow deer. This space exhibited the most significant change in land cover between 2001 and 2020, with the area dramatically switching from brown ‘plowed’ fields and grassland to shrubs, woody vegetation and trees. Conservationists who led the study say that these changes would have reinvigorated support for important ecosystem functions including food sources, habitats, water and soil retention.
Lead author, and ZSL researcher, Henrike Schulte to Bühne said: “This study is the first of its kind to assess the impacts of rewilding on wider ecosystem functions over several decades and at scale, in the UK. The Knepp Estate is becoming a lush and thriving natural habitat, and by using freely available, satellite data, we have deepened our understanding of the impacts made by rewilding efforts.”
Measuring the impacts of long-term rewilding projects, such as Knepp, has thus far been a challenge. This study is the first in the UK to use satellite images to assess the long-term impacts of rewilding as a strategy for a nature positive future.
Schulte to Bühne added: “Earth observation tools have been vital in helping us to understand more about rewilding and how it's working. We hope that our work has proven how successful it is, and will be used to assess the impact of other rewilding projects in the future.”
The findings also showed a significant increase in green vegetation, which the researchers believe cannot be entirely explained by rewilding efforts alone. They suggest these changes could also be attributed to the impacts of warming conditions in South England due to climate change. As climate change is causing broad and damaging shifts in nature, this will need to be monitored closely, and satellite imagery could help.
Senior author and climate change and biodiversity expert at ZSL, Dr Nathalie Pettorelli said: “Restoring nature in the context of rapid environmental change is challenging. To inform conservation action, we need a range of reliable tools that help us assess and predict the impacts of our efforts in the context of rapid changes in climatic conditions; as this study has shown, satellite data are, in that respect, extremely useful.
“Alongside the IUCN’s recent resolution on rewilding, there has been a broad interest in the development of guidelines to monitor the ecological impacts of rewilding projects. Here at ZSL, we would like to see governments, landowners and policy makers across the UK putting nature at the heart of decision making, prioritising biodiversity loss and recognising its interconnections with other environmental issues such as climate change.
“The good thing about satellite data is that you can go back in time and look for data from a time passed, so it presents itself as an ideal tool to help with monitoring the work being done to help restore nature.”
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