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Litter Quality of Two Remnant Tree Species Affects Soil Microbial Activity in Tropical Seasonal Pastures in Western Mexico

2011; Taylor & Francis; Volume: 25; Issue: 1 Linguagem: Inglês

10.1080/15324982.2010.528148

1532-4990

Leopoldo Galicia, Felipe Garcı́a-Oliva,

Invertebrate Taxonomy and Ecology

Abstract In degraded soils of tropical seasonal pastures, native remnant tree species that differ in foliar morphology, litter quality, and quantity might be quite useful as an organic input for improving soil fertility. The objective of this study was to analyze litter quality effects on soil microbial activity from two native remnant trees: Caesalpinia eriostachys Benth. (Caesalnaceae) and Cordia elaeagnoides DC (Boraginaceae), located within a tropical seasonal pasture matrix dominated by Panicum maximum Jacq. (Poaceae). The substrate-induced respiration method was used to determine soil microbial activity in a laboratory incubation experiment. A 3 × 3 factorial laboratory experiment for litter type and soil origin was carried out by adding leaf litter to soil in a reciprocal fashion to evaluate the relative effect of litter quality on substrate-induced respiration. Potential C mineralization rate and net microbial C immobilization from soil under C. elaeagnoides and C. eriostachys were higher with endogenous litter (260 ± 24 µg C g−1 d−1 and 242 ± 11 µg C g−1 d−1 for C. elaeagnoides and C. eriostachys, respectively) than with exogenous litter. Potential carbon mineralization and net microbial C immobilization in soil under P. maximum increased with litter from C. eriostachys due to other leaf-litter quality parameters as lignin concentration and lignin:N ratio. Therefore, C. eriostachys litter addition on soil under grass species may help to stabilize soil organic matter, promoting soil microbial biomass and activity. The net immobilization of microbial N under two remnant tree species and grass species was negative, indicating an N mineralization from microbial biomass. Keywords: potential C mineralizationsoil microbial carbonsoil microbial nitrogensoil rehabilitationtree species effectstropical deciduous forest The authors thank Georgina García-Méndez for her assistance in the laboratory analysis, Heberto Ferreira and Alberto Valencia for their help in data processing, Ramiro Peña of San Mateo for allowing us to use his pastures, and the personnel of Chamela Biological Station, UNAM, for logistic support during the field work. Funds for this research were provided by DGAPA – UNAM and CONACyT-Mexico (Grant No. G27674-N). Notes Numbers are averages (n = 5) and numbers in parentheses correspond to the standard error. Different letters indicate a statistically significant difference between species (P < 0.05) using Tukey's HSD multiple comparison. Values within a row followed by different letters among the plant species differ at P < 0.05 (Tukey's HSD multiple comparison). Values within the plant species and among leaf litter treatments followed by a different letter differ at P < 0.05 (Tukey's HSD multiple comparison). Lowercase letter indicates response of one soil to litter amendment, and uppercase letter indicates litter effect on soil under other species.