Abstract:
Soil fauna can influence soil processes through interactions with the microbial community. Due to the complexity of the functional roles of fauna and their effects on microbes, little consensus has been reached on the extent to which soil fauna can regulate microbial activities. We quantified soil microbial biomass and maximum growth rates in control and fauna-excluded treatments in dry and wet tropical forests and north- and south-facing subalpine forests to test whether soil fauna effects on microbes are different in tropical and subalpine forests. Exclusion of fauna was established by physically removing the soil macrofauna and applying naphthalene. The effect of naphthalene application on the biomass of microbes that mineralize salicylate was quantified using the substrate induced growth response method. We found that: (1) the exclusion of soil fauna resulted in a higher total microbial biomass and lower maximum growth rate in the subalpine forests, (2) soil fauna exclusion did not affect the microbial biomass and growth rate in the tropical forests, and (3) the microbial biomass of salicylate mineralizers was significantly enhanced in the fauna-exclusion treatment in the tropical wet and the south-facing subalpine forests. We conclude that non-target effects of naphthalene on the microbial community alone cannot explain the large differences in total microbial biomass found between control and fauna-excluded treatments in the subalpine forests. Soil fauna have relatively larger effects on the microbial activities in the subalpine forests than in tropical dry and wet forests.

Author Keywords:
soil fauna, tropics, subalpine, naphthalene, substrate induced growth response

KeyWords Plus:
MICROBIAL FUNCTIONAL-GROUPS, LEAF LITTER, BIOMASS, DECOMPOSITION, DYNAMICS, FIELD, MICROORGANISMS, NAPHTHALENE, COLLEMBOLAN, SUBSTRATE

Addresses:
Gonzalez G, US Forest Serv, Int Inst Trop Forestry, POB 25000, San Juan, PR 00928 USA
Univ Colorado, Inst Arctic & Alpine Res, Boulder, CO 80309 USA
Univ Colorado, Dept Epo Biol, Boulder, CO 80309 USA
Univ Puerto Rico, Inst Trop Ecosyst Studies, San Juan, PR 00936 USA

Publisher:
SPRINGER-VERLAG, 175 FIFTH AVE, NEW YORK, NY 10010 USA

IDS Number:
468LJ

ISSN:
0029-8549