Subalpine grassland carbon balance during 7 years of increased atmospheric N deposition
| Autor: | Jan Enderle, Seraina Bassin, Matthias Volk |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
010504 meteorology & atmospheric sciences
lcsh:Life 01 natural sciences Sink (geography) Grassland Animal science lcsh:QH540-549.5 Grazing Ecosystem Ecology Evolution Behavior and Systematics 0105 earth and related environmental sciences Earth-Surface Processes geography geography.geographical_feature_category Ecology Crop yield lcsh:QE1-996.5 04 agricultural and veterinary sciences Soil carbon lcsh:Geology lcsh:QH501-531 Plant productivity 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Environmental science Montane ecology lcsh:Ecology |
| Zdroj: | Biogeosciences, Vol 13, Iss 12, Pp 3807-3817 (2016) |
| ISSN: | 1726-4189 |
| DOI: | 10.5194/bg-13-3807-2016 |
| Popis: | Air pollution agents interact when affecting biological sinks for atmospheric CO2, e.g., the soil organic carbon (SOC) content of grassland ecosystems. Factors favoring plant productivity, like atmospheric N deposition, are usually considered to favor SOC storage. In a 7-year experiment in subalpine grassland under N- and O3-deposition treatment, we examined C fluxes and pools. Total N deposition was 4, 9, 14, 29 and 54 kg N ha−1 yr−1 (N4, N9, etc.); annual mean phytotoxic O3 dose was 49, 65 and 89 mmol m−2 projected leaf area. We hypothesized that between years SOC of this mature ecosystem would not change in control treatments and that effects of air pollutants are similar for plant yield, net ecosystem productivity (NEP) and SOC content, leading to SOC content increasing with N deposition. Cumulative plant yield showed a significant N and N × N effect (+38 % in N54) but no O3 effect. In the control treatment SOC increased significantly by 9 % in 7 years. Cumulative NEP did show a strong, hump-shaped response pattern to N deposition with a +62 % increase in N14 and only +39 % increase in N54 (N effect statistically not significant, N × N interaction not testable). SOC had a similar but not significant response to N, with highest C gains at intermediate N deposition rates, suggesting a unimodal response with a marginal (P = 0.09) N × N interaction. We assume the strong, pollutant-independent soil C sink developed as a consequence of the management change from grazing to cutting. The non-parallel response of SOC and NEP compared to plant yield under N deposition is likely the result of increased respiratory SOC losses, following mitigated microbial N-limitation or priming effects, and a shift in plant C allocation leading to smaller C input from roots. |
| Databáze: | OpenAIRE |
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