From farmlands to forests: Understanding the effects of rewilding on soils
Learn how to collect soil data with our new video guide!
While many studies have explored how the presence of vegetation and animals change during rewilding, the hidden world of soil has received far less attention. Yet, soils represent the largest terrestrial carbon pool, and accommodate more than half of the Earth’s biodiversity. There’s still a lot we don’t know about how carbon stocks and soil biodiversity respond when nature is left to recover on its own. This is partly because soil is incredibly complex, expensive to study, and varies greatly from place to place.
The WILDCARD project is working to close this gap. By collecting data on soil carbon and biotic communities, the latter using advanced environmental DNA (eDNA) techniques, we aim to better understand how soils respond to rewilding. This will help us learn more about the role of soil in storing carbon and supporting biodiversity.
Instructional videos
To support the WILDCARD consortium and other organisations involved in the project, our partner Research Institute for Nature and Forest (INBO) created a series of videos that explain the steps for collecting soil samples. These videos complement the project’s written soil sampling guide, developed by INBO and the Silva Tarouca Research Institute (VUKOZ), making it easier to follow the process in the field. The information gathered will help us track changes in soil carbon and biodiversity as rewilding progresses in forests where management was halted and on abandoned farmland. The videos and soil sampling protocol can aid other projects and researchers in doing similar investigations, thus generating consistent and harmonised data across different initiatives.
Discover our video guide:
Video #1 Sampling the forest floor
This video shows how to collect samples from the forest floor using a frame with a known surface area. It covers the steps of:
- Identifying the fresh litter layer (OL) and fragmented and partly decomposed forest floor layer (OFH) and telling them apart from the mineral soil underneath.
- Measuring the thickness of each layer.
- Preparing samples to study their mass, chemical composition, and biodiversity using eDNA.
Video #2 Taking undisturbed soil samples
This video explains how to collect undisturbed soil samples from set depths (0–100 cm) using metal rings with a known volume. These samples are used to measure soil bulk density and the amount of stones (coarse material).
Video #3 Mixing composite samples and taking subsamples
This video demonstrates how to mix soil from different spots within the plot, to create a representative sample for each layer. It also shows the steps to:
- Taking smaller samples for chemical and eDNA tests.
- Properly bagging, labeling, and recording the samples.
- Storing eDNA samples temporarily in a car-based freezer.
Video #4 Taking disturbed soil samples
Learn how to use a soil auger to collect disturbed soil samples from set depths (0–100 cm). These samples are tested for chemical properties over the entire depth range and for biodiversity, focusing on the 0–10 cm layer.
Video #5 Description and classification of terrestrial humus forms
This video explains how to classify the forest floor into different humus forms using a small soil pit. It highlights key features of the forest floor layers and the A horizon to help identify the humus form.
Where will we collect soil data?
The data collected using our soil sampling protocol will be used to study how rewilding affects carbon storage and biodiversity in different environments on the European continent, with a special focus on so-called High-Intensity Sites (HIS). These are carefully chosen locations that represent different ecological and climatic conditions, past land uses, classes of time since abandonment, and where additional data will be collected by WILDCARD.
At HIS-aboveground, our researchers use advanced tools like terrestrial laser scanning (TLS) and unoccupied aerial laser scanning (ULS) to map forest structures and explore their links to biodiversity. At HIS-belowground, the focus is on soil—sampling for chemical and physical properties and analysing eDNA from the mineral soil and forest floor in approximately 300 locations. By targeting these High-Intensity Sites, the project ensures comprehensive coverage and gathers detailed data to understand how ecosystems recover and thrive when left to rewild. This knowledge will help shape strategies for healthier landscapes and better climate solutions.
Banner photo credit: Research Institute for Nature and Forest (INBO)