Mapping vegetation dynamics in a rewilded grassland with UAV-LiDAR

During Jaime's postdoc, he explores the ecological effects of rewilding in a temperate North European grassland (Mols research site), specifically focusing on the dynamics of shrub encroachment and biomass allocation. His research is driven by the need to better understand how rewilding practices, which aim to restore natural landscapes and biodiversity by reducing human intervention, impact vegetation dynamics and nutrient cycling. A key concern in this context is shrub encroachment, which can threaten plant biodiversity and disrupt balanced ecosystem functions.

The research addresses several specific objectives:

1. Horizontal Spread of Shrubs: It investigates how shrubs, particularly Cytisus scoparius (Scotch broom), a nitrogen-fixing leguminous species, spread horizontally over time (i.e. encroachment). Processes like resprouting, colonization, and recruitment are studied to capture shrub population dynamics in a rewilded grassland environment.
2. Vertical Biomass Allocation: It examines changes in the vertical structure of shrub biomass in response to factors like herbivory and growth, which affect how shrubs allocate resources to above-ground versus below-ground biomass.
3. Vegetation Biomass Allocation under Grazing Pressure: By using exclosure plots (which prevent herbivores from grazing) and a gradient of grazing intensity, the research explores how grazing affects the overall vegetation biomass distribution and composition.

The methodology integrates technologies such as UAV-LiDAR (unmanned aerial vehicles equipped with light detection and ranging) for detailed 3D monitoring of vegetation, alongside traditional botanical surveys for ground-truthing and detailed plot-level analyses. The study spans seven years (2018–2024) with a focus on one specific year (2020–2021) that included more frequent surveys to capture finer temporal dynamics.

By combining landscape-level UAV LiDAR data with plot-based field metrics, the research provides insights into the effects of rewilding on shrub dynamics, biomass distribution, and ecosystem functioning. This study is expected to inform land management practices, especially regarding the role of herbivory and shrub encroachment in maintaining balanced ecosystems in rewilded grasslands.