期刊
BIOGEOCHEMISTRY
卷 114, 期 1-3, 页码 313-326出版社
SPRINGER
DOI: 10.1007/s10533-012-9812-2
关键词
Leaf litter; Ecoenzymes; Nutrient limitation; Soil organic matter; Tropics
资金
- National Science Foundation [DEB-0515744, DEB-0852916]
- Direct For Biological Sciences
- Division Of Environmental Biology [0919080] Funding Source: National Science Foundation
- Directorate For Geosciences
- Division Of Earth Sciences [0918835] Funding Source: National Science Foundation
Soil extracellular enzymes mediate organic matter turnover and nutrient cycling yet remain little studied in one of Earth's most rapidly changing, productive biomes: tropical forests. Using a long-term leaf litter and throughfall manipulation, we explored relationships between organic matter (OM) inputs, soil chemical properties and enzyme activities in a lowland tropical forest. We assayed six hydrolytic soil enzymes responsible for liberating carbon (C), nitrogen (N) and phosphorus (P), calculated enzyme activities and ratios in control plots versus treatments, and related these to soil biogeochemical variables. While leaf litter addition and removal tended to increase and decrease enzyme activities per gram soil, respectively, shifts in enzyme allocation patterns implied changes in relative nutrient constraints with altered OM inputs. Enzyme activity ratios in control plots suggested strong belowground P constraints; this was exacerbated when litter inputs were curtailed. Conversely, with double litter inputs, increased enzymatic investment in N acquisition indicated elevated N demand. Across all treatments, total soil C correlated more strongly with enzyme activities than soluble C fluxes, and enzyme ratios were sensitive to resource stoichiometry (soil C:N) and N availability (net N mineralization). Despite high annual precipitation in this site (MAP similar to 5 m), soil moisture positively correlated with five of six enzymes. Our results suggest resource availability regulates tropical soil enzyme activities, soil moisture plays an additional role even in very wet forests, and relative investment in C, N and P degrading enzymes in tropical soils will often be distinct from higher latitude ecosystems yet is sensitive to OM inputs.
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