Effects of Forest Management Scenarios on Water Partitioning and Ecosystem Resilience: Insights from Long-Term Tracer-Aided Ecohydrological Modelling in a Drought-Sensitive Lowland Catchment

Forests are essential regulators of water, energy, and carbon cycles, emphasizing the need for sustainable forest management under changing climate conditions. Forest management practices, including regeneration and structural changes, impact species composition and densities which have feedback effects on the water balance, partitioning into blue and green water fluxes, and the ecohydrological resilience of these ecosystems. Quantifying and understanding these impacts is critical for maintaining water availability, sustaining livelihoods, and reducing disaster risks, especially in drought-prone regions. This study investigates blue and green water partitioning and its implications for ecosystem resilience under generic forest management scenarios using modelling experiments. These explore variations in forest density, tree species composition (e.g., deciduous, coniferous, agroforestry), and root distribution. Using the tracer-aided conceptual ecohydrology model Ecoplot, baseline simulations (2000–2024) were conducted in the drought-sensitive Demnitzer Millcreek catchment, Germany. The model was calibrated and validated with seven years of soil moisture data and three years of soil water isotope data using a multi-criteria approach. Results showed that coniferous forests transpire more water than deciduous forests and agroforestry stands, while mixed forests enhance ecosystem resilience during droughts by increasing blue water fluxes. Significant differences in water partitioning between dry and wet years were observed across contrasting management scenarios. The findings underscore the importance of mixed forests in mitigating drought impacts and offer a framework for quantifying, visualizing and communicating the implications of land use changes on water availability. These insights are critical for informed decision-making and stakeholder engagement, highlighting the need for integrated strategies to improve forest resilience and ensure sustainable water resource management.