Cycling and retention of nitrogen in European beech (Fagus sylvatica L.) ecosystems under elevated fructification frequency
| Autor: | Markus Wagner, Uwe Klinck, Partap Khanna, Rainer Brumme, Christoph Schulz, Joachim Block, Henning Meesenburg, Bernd Ahrends |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
0106 biological sciences
Fructification 010504 meteorology & atmospheric sciences biology Chemistry Phosphorus chemistry.chemical_element 15. Life on land Plant litter biology.organism_classification 01 natural sciences Nutrient Fagus sylvatica Agronomy 13. Climate action Soil water Cycling Beech Ecology Evolution Behavior and Systematics 010606 plant biology & botany 0105 earth and related environmental sciences Earth-Surface Processes |
| Zdroj: | Biogeosciences. 18:3763-3779 |
| ISSN: | 1726-4189 |
| Popis: | Atmospheric deposition of nitrogen (N) has exceeded its demand for plant increment in forest ecosystems in Germany. High N inputs increased plant growth, the internal N cycling within the ecosystem, the retention of N in soil and plant compartments, and the N output by seepage water. But the processes involved are not fully understood, notably the effect of fructification in European beech (Fagus sylvatica L.) on N fluxes. The frequency of fructification has increased together with air temperature and N deposition, but its impact on N fluxes and the sequestration of carbon (C) and N in soils have been hardly studied. A field experiment using 15 N-labeled leaf litter exchange was carried out over a 5.5-year period at seven long-term European beech (Fagus sylvatica L.) monitoring sites to study the impact of current mast frequency on N cycling. Mean annual leaf litterfall contained 35 kg N ha −1 , but about one-half of that was recovered in the soil 5.5 years after the establishment of the leaf litter 15 N exchange experiment. In these forests, fructification occurred commonly at intervals of 5 to 10 years, which has now changed to every 2 years as observed during this study period. Seed cupules contributed 51 % to the additional litterfall in mast years, which creates a high nutrient demand during their decomposition due to the very high ratios of C to N and C to phosphorus (P). Retention of leaf litter 15 N in the soil was more closely related to the production of total litterfall than to the leaf litterfall, indicating the role of seed cupules in the amount of leaf N retained in the soil. Higher mast frequency increased the mass of mean annual litterfall by about 0.5 Mg ha −1 and of litterfall N by 8.7 kg ha −1 . Mean net primary production (NPP) increased by about 4 %. Mean total N retention in soils calculated by input and output fluxes was unrelated to total litterfall, indicating that mast events were not the primary factor controlling total N retention in soils. Despite reduced N deposition since the 1990s, about 5.7 out of 20.7 kg N ha −1 deposited annually between 1994 and 2008 was retained in soils, notably at acid sites with high N / P and C / P ratios in the organic layers and mineral soils, indicating P limitation for litter decomposition. Trees retained twice as much N compared to soils by biomass increment, particularly in less acidic stands where the mineral soils had low C / N ratios. These results have major implications for our understanding of the C and N cycling and N retention in forest ecosystems. In particular the role of mast products in N retention needs more research in the future. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|