Ecoenzymatic stoichiometry of microbial nutrient acquisition in tropical soils

Bonnie Grace Waring, Samantha Rose Weintraub, Robert L. Sinsabaugh

Research output: Contribution to journalArticlepeer-review

142 Scopus citations

Abstract

The relative activities of soil enzymes involved in mineralizing organic carbon (C), nitrogen (N), and phosphorus (P) reveal stoichiometric and energetic constraints on microbial biomass growth. Although tropical forests and grasslands are a major component of the global C cycle, the effects of soil nutrient availability on microbial activity and C dynamics in these ecosystems are poorly understood. To explore potential microbial nutrient limitation in relation to enzyme allocation in low latitude ecosystems, we performed a meta-analysis of acid/alkaline phosphatase (AP), β-1,4-glucosidase (BG), and β-1,4-N-acetyl-glucosaminidase (NAG) activities in tropical soils. We found that BG:AP and NAG:AP ratios in tropical soils are significantly lower than those of temperate ecosystems overall. The lowest BG:AP and NAG:AP ratios were associated with old or acid soils, consistent with greater biological phosphorus demand relative to P availability. Additionally, correlations between enzyme activities and mean annual temperature and precipitation suggest some climatic regulation of microbial enzyme allocation in tropical soils. We used the results of our analysis in conjunction with previously published data on soil and biomass C:N:P stoichiometry to parameterize a biogeochemical equilibrium model that relates microbial growth efficiency to extracellular enzyme activity. The model predicts low microbial growth efficiencies in P-limited soils, indicating that P availability may influence C cycling in the highly weathered soils that underlie many tropical ecosystems. Therefore, we suggest that P availability be included in models that simulate microbial enzyme allocation, biomass growth, and C mineralization.

Original languageEnglish (US)
Pages (from-to)101-113
Number of pages13
JournalBiogeochemistry
Volume117
Issue number1
DOIs
StatePublished - Jan 2014

Keywords

  • Carbon use efficiency
  • Ecological stoichiometry
  • Nutrient limitation
  • Resource allocation model
  • Soil enzymes
  • Tropical forest

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