Publication Date:
2015-05-01
Description:
Soil microbial nutrient constraints along a tropical forest elevation gradient: a belowground test of a biogeochemical paradigm Biogeosciences Discussions, 12, 6489-6523, 2015 Author(s): A. T. Nottingham, B. L. Turner, J. Whitaker, N. Ostle, N. P. McNamara, R. D. Bardgett, N. Salinas, and P. Meir Aboveground primary productivity is widely considered to be limited by phosphorus (P) availability in lowland tropical forests and by nitrogen (N) availability in montane tropical forests. However, the extent to which this paradigm applies to belowground processes remains unresolved. We measured indices of soil microbial nutrient status in lowland, sub-montane and montane tropical forests along a natural gradient spanning 3400 m in elevation in the Peruvian Andes. With increasing elevation there were marked increases in soil concentrations of total N, total P, and readily-extractable P, but a decrease in N mineralization determined by in situ resin bags. Microbial carbon (C) and N increased with increasing elevation, but microbial C:N:P ratios were relatively constant, suggesting homeostasis. The activity of hydrolytic enzymes, which are rich in N, decreased with increasing elevation, while the ratios of enzymes involved in the acquisition of N and P increased with increasing elevation, further indicating a shift in the relative demand for N and P by microbial biomass. We conclude that soil microorganisms shift investment in nutrient acquisition from P to N between lowland and montane tropical forests, suggesting that different nutrients regulate soil microbial metabolism and the soil carbon balance in these ecosystems.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
