Decreasing before increasing: Evolution of nitrogen availability conditions in French forest ecosystems over the last century according to forest herbs
نویسندگان
چکیده
Based on a large number of floristic plots (n = 82 581), the French forest status related to soil nitrogen (N) availability was reconstructed from herb species bio-indication spanning from1910 to 2010. The temporal changes highlighted a decrease in available-N until 1990s in coniferous and broadleaved forests (mean ΔC:N=+0.79 and +0.74 C:N units, respectively). It was followed by an increase in available-N until 2010, in both coniferous and broadleaved forests (mean ΔC:N=-0.10 and-0.16 C:N units, respectively). Spatially, our results confirm the temporal trends, and highlight the center-to-south of France as mainly impacted by the increased N availability in both forest types. The observed decrease in available-N may be related to acidification impacting on soil processes while the recent increase is consistent with the current cessation of acidification. The past N deposition is still impacting both forest soils and vegetation.
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