Model-aided quantification of dissolved carbon and nitrogen release afterwindthrow disturbance in an Austrian karst system

[摘要] Karst systems are important for drinking water supply. Future climateprojections indicate increasing temperature and a higher frequency of strongweather events. Both will influence the availability and quality of waterprovided from karst regions. Forest disturbances such as windthrow candisrupt ecosystem cycles and cause pronounced nutrient losses from theecosystems. In this study, we consider the time period before and after thewind disturbance period (2007/08) to identify impacts on DIN (dissolvedinorganic nitrogen) and DOC (dissolved organic carbon) with a process-basedflow and solute transport simulation model. When calibrated and validated beforethe disturbance, the model disregards the forest disturbance and itsconsequences on DIN and DOC production and leaching. It can therefore beused as a baseline for the undisturbed system and as a tool for thequantification of additional nutrient production. Our results indicate thatthe forest disturbance by windthrow results in a significant increase of DINproduction lasting  ∼  3.7 years and exceeding thepre-disturbance average by 2.7 kg ha⁻¹ a⁻¹ corresponding to an increase of53 %. There were no significant changes in DOC concentrations. Withsimulated transit time distributions we show that the impact on DIN travelsthrough the hydrological system within some months. However, a small fraction ofthe system outflow (< 5 %) exceeds mean transit times of> 1 year.

[学科分类] 地球化学与岩石