Carsten Marohn1, Reinhold Jahn2 and Joachim Sauerborn1
On seven sites in Western Leyte, Philippines, different land uses, namely reforestation with indigenous tree species (‘rainforestation’), reforestation with exotic tree specie Gmelina arborea, and traditional fallow/grassland use were compared with respect to soil biological activity. Analysed parameters were Basal Respiration (BR), microbial carbon (Substrate-Induced Respiration method, Cmic SIR) and leaf litter decomposition. Correlations between BR, SIR, metabolic quotient (qCo2), soil organic carbon (Corg), soil N (NT) and pH were assessed. BR and Cmic SIR as well as the metabolic quotient qCo2 (BR/SIR) proved to be sensitive parameters and the methods gave reproducible values to distinguish sites and land-uses in most cases. However, due to differences among fallow / grassland treatments, a uniform tendency between these and rainforestation was not observed. On the other hand, BR and Cmic SIR were significantly higher under Gmelina than under either of the other land-uses. Correlations between parameters were strongest for BR vs Corg and BR vs. pH as well for Cmic SIR vs. Corg and qCo2 vs. Corg.
Keywords: soil biological activity; basal respiration; Substrate-Induced Respiration; land-use; reforestation.