Identification of General Patterns of Nutrient and Labile Carbon Control on Soil Carbon Dynamics Across a Successional Gradient |
| |
Authors: | Alexandru Milcu Angela Heim Richard J Ellis Stefan Scheu Pete Manning |
| |
Institution: | 1.Division of Biology, NERC Centre for Population Biology,Imperial College London,Ascot,UK;2.Department of Earth and Environmental Sciences,University of Potsdam,Potsdam,Germany;3.Veterinary Laboratories Agency, VLA Weybridge,New Haw,UK;4.J.F. Blumenbach Institute of Zoology and Anthropology,Georg-August-University G?ttingen,G?ttingen,Germany;5.School of Agriculture, Food and Rural Development,Newcastle University,Newcastle,UK |
| |
Abstract: | Carbon (C) inputs and nutrient availability are known to affect soil organic carbon (SOC) stocks. However, general rules regarding
the operation of these factors across a range of soil nutrient availabilities and substrate qualities are unidentified. “Priming”
(stimulated decomposition by labile C inputs) and ‘preferential substrate utilization’ (retarded decomposition due to shifts
in community composition towards microbes that do not mineralize SOC) are two hypotheses to explain effects of labile C additions
on SOC dynamics. For effects of nutrient additions (nitrogen and phosphorus) on SOC dynamics, the stoichiometric (faster decomposition
of materials of low carbon-to-nutrient ratios) and ‘microbial mining’ (that is, reduced breakdown of recalcitrant C forms
for nutrients under fertile conditions) hypotheses have been proposed. Using the natural gradient of soil nutrient availability
and substrate quality of a chronosequence, combined with labile C and nutrient amendments, we explored the support for these
contrasting hypotheses. Additions of labile C, nitrogen (N), phosphorus (P), and combinations of C and N and C and P were
applied to three sites: 2-year fallow grassland, mature grassland and forest, and the effects of site and nutrient additions
on litter decomposition and soil C dynamics were assessed. The response to C addition supported the preferential substrate
hypothesis for easily degradable litter C and the priming hypothesis for SOC, but only in nitrogen-enriched soils of the forest
site. Responses to N addition supported the microbial mining hypothesis irrespective of C substrate (litter or SOC), but only
in the forest site. Further, P addition effects on SOC support the stoichiometric hypothesis; P availability appeared key
to soil C release (priming) in the forest site if labile C and N is available. These results clearly link previously contrasting
hypotheses of the factors controlling SOC with the natural gradient in litter quality and nutrient availability that exists
in ecosystems at different successional stages. A holistic theory that incorporates this variability of responses, due to
different mechanisms, depending on nutrient availability and substrate quality is essential for devising management strategies
to safeguard soil C stocks. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|