水保所知识产出(1956---)知识库

The ecological productivity of the Robinia pseudoacacia L. (RP) widely cultivated on the Loess
hilly region has been widely questioned with its aging. Soil microbial biomass (SMB) plays a key role
in soil nutrient dynamics and productivity of the ecosystems. Understanding the main ecological
drivers of SMB is supposed to be of importance for ecosystem functioning of RP in the Loess hilly
region. In this study, we identified the most influential factors affecting SMB at 2 layers (0–10 cm and
10–30 cm) using forward selection in terms of plant characteristics (forest age, tree height, diameter at
breast height, tree canopy, crown base height, herb height, herb number, herb coverage, herb ground
diameter and herb diversity), soil physiochemical characteristics (soil bulk density, pH, water content,
soil organ carbon, soil total and available nutrient content) and topographical properties (elevation,
aspect and slope). We also analyzed individual and interactive effects (plant–soil, plant–topography,
soil–topography, plant–soil–topography) using general linear model (GLM) analysis. Among all
plant variables, tree canopy and understory richness had the greatest impact on SMB. The soil
variables with the greatest impact on SMB were bulk density and available phosphorus. Elevation
was the most important topographic factor affecting SMB. When we considered the interactive effects
among plant, soil physicochemical and topographical variables on SMB, a significant interaction
effect occurred at a depth of 10–30 cm soil layer. We concluded that individual effects of abiotic and
biotic factors significantly affect SMB at 0–10 cm, while the interaction of these factors mainly played
roles at 10–30 cm. These results provide a basis for maintaining soil health and productivity using
efficient SMB by providing suitable abiotic and biotic habitats.