Bio-geomorphological significance of vegetation Insights from humid and semi-arid environments

Vegetation plays a crucial role in shaping Earth's surface by influencing geomorphological processes across various scales, from local landscapes to global sediment systems. Key components like leaf litter and spatial patterns affect processes such as erosion and sediment transport. To better understand how landscapes develop, it's important to explore how vegetation interacts with other Earth system factors, including climate, hydrology, geology, and topography. This thesis aims to improve the understanding of vegetation-landscape interactions and their representation in geomorphic models. It first provides a systematic review of how vegetation affects geomorphological processes and how these effects are currently incorporated into models. Next, it examines how vegetation influences landscapes in different climates, comparing humid regions with abundant water and semi-arid regions where water is limited. The study focuses on two semi-natural ecosystems: a temperate forest in Luxembourg, which is formed on weathering-prone marl, and a semi-arid hillslope in southeastern Spain, shaped by a mix of marl and limestone. The findings reveal that the roles of vegetation in current models are still relatively simplified. Emergent landscape features are not driven solely by vegetation cover. Other factors, such as litter quality, and the spatial distribution of vegetation and its litter, also play crucial roles. The thesis concludes that to better understand how vegetation shapes landscapes, future studies should consider a wider range of vegetation-related factors and interactions.