Eutrofication impacted temperate forest vegetation recently

Abstract

Abstract1. Nitrogen (N) is a key nutrient elements for ecosystems which has been highly impacted by human development and activities since the early 20 th century. Despite that changes in N-availability have been demonstrated to impact forests, we still miss evidence of its effect on species composition over the long-term.2. Based on a large number of floristic observations (n = 45 604), the French forest status related to soil N-availability was reconstructed from herb species assemblage between 1910 and 2010 using both a bioindication approach and a spatiotemporal sampling aiming to pair past and recent floristic observations.3. We showed that soil N content bioindicated from forest herb communities was higher at the start of impacted the understory species composition of forest. We evidenced changes in communities towards less nitrophilous plant assemblage followed by a recent eutrophication since 2005. We propose that the nitrogen forest vegetation status is likely related to N atmospheric deposition trend, but also to both acidification, climate change and forestry management which impacted organic matter decomposition and soil N mineralization through effects on soil microbial and fauna activities. The current

Ecological constraints increase the climatic debt in forests

“…Soil conditions drive floristic changes, both directly2751 (for example, when a nutrient stress adds to the climatic one) and indirectly (for example, when the climatic constraint is alleviated by good soil conditions)33. In the absence of direct soil observations over the 67,289 surveys, soil pH ( pH ) and C:N ratio ( N ) were inferred from a bioindication model using the floristic assemblage to predict soil pH51 and C:N ratio52 (RMSD=0.9 and 3.1 for 254 independent pH and C:N ratio observations, respectively; Supplementary Fig. 10).…”