Effect of demand-driven fertilization on water chemistry : an assessment of Undersvik project

Sammanfattning

Demand-driven fertilization is a silvicultural practice designed to enhance forest productivity while minimizing nutrient losses to aquatic systems. This study assesses the impact of demand-driven fertilization on water chemistry at the Undersvik High-Yield Experimental Forest in Sweden, analysing nutrient concentrations and exports from nine monitored sites. Using statistical models, including the Durbin-Watson test, Generalized Least Squares and Kruskal-Wallis’s test, we examined temporal trends in dissolved organic carbon (DOC), nitrogen (NO₂+NO₃, NH₄, dissolved N), and phosphate (PO₄). The results indicate that DOC and PO₄ concentrations showed significant spatial variation, with treated sites displaying transient increases post-fertilization, particularly following the second application in June 2022. However, no clear long-term effects were detected, suggesting that hydrological variability may overshadow fertilization impacts. Continued monitoring is necessary to distinguish between fertilization-driven nutrient leaching and natural fluctuations. This study provides insights into the environmental trade-offs of intensive forestry and contributes to sustainable forest management discussions.