Topographic controls on ecosystem evapotranspiration and net primary productivity under climate warming in the Taihang Mountains, China

Abstract:

In mountain environments, topography is a key control of alpine ecosystems and corresponding ecohydrological processes. This paper examines the influence of topography on variations in mountain ecohydrology under climate warming in the Taihang Mountains in China. The ecosystem model BioGeochemicalCycles (BIOME-BGC) was used to evaluate ecosystem evapotranspiration (ET) and net primary productivity (NPP) for deciduous broadleaf trees, shrubs and grass at different elevation gradients and changes in these variables under a 3℃-warming scenario with no precipitation changes. The results showed that the ET and NPP of deciduous broadleaf trees and shrubs increased with elevation below 1500 m and decreased with elevation above 1500 m. The NPP and ET of deciduous broadleaf trees and shrubs decreased in response to warming below 1500 m, and increased above 1500 m. For grass, the ET and NPP slightly decreased with greater elevation and increased under climate warming. The impacts of precipitation on ET and NPP placed deciduous broadleaf trees under energy stress in high elevation areas. Shrubs were influenced by water conditions, with an optimal precipitation of 600 mm, and climate warming will increase the upper threshold of water stress. Grass was under energy stress at all elevations. This study provides scientific support for future management of mountain ecosystems and water resources.