坡位对东灵山辽东栎林土壤微生物量的影响

Abstract

Soil microbial biomass is an important component of terrestrial ecosystem and plays an important role in the nutrient cycle and energy transformation in forest ecosystem.With its great sensitivity to the environmental conditions,the size of soil microbial biomass can be affected by a number of factors.As an important geographic factor,slope position can affect the soil microbial biomass by influencing soil microclimate,soil physical and chemical properties,vegetation growth and below-ground carbon input.Soil microbial biomass at slope scale has not been well studied as far as we know,and most of the previous studies of this topic chose a single mountain slope as study area,lacking of comparison among different slope positions in the entire distribution of one plant species.To address this question,we selected 10 west slopes along the altitudinal gradient of Quercus liaotungensis forest,with altitude ranging from 1000m to 1800m in Dongling Mountain of Beijing as our study area.A total of 357 soil samples were collected to compare the differences of soil microbial biomass on different slope positions,in which,120 samples belonged to top slope,138 samples belonged to middle slope and 99 belonged to bottom slope.Soil microbial biomass was measured using chloroform fumigation-extraction method.Soil and vegetation factors were also tested.Analysis of variance(ANOVA),partial correlation analysis and path analysis were used to investigate the difference in soil microbial biomass on different slope positions and their influencing factors.ANOVA analysis showed that microbial biomass carbon and nitrogen from different slope positions were not significantly different(with P0.05),while the soil properties showed significant differences(P0.05): soil moisture,soil organic carbon and total soil nitrogen was significantly higher on bottom slopes than that on middle slopes and top slopes.Soil pH and herbal richness had no significant difference among slope positions(with P0.05).Partial correlation analysis showed that the microbial biomass had significant positive correlations with soil moisture,soil organic carbon and total soil nitrogen(with P0.05),and a significant negative correlation with herbal richness(with P0.05).Further path analysis showed that on top and middle slope positions,soil moisture and soil organic carbon were important factors,while the negative effect of herbal richness was significant on bottom slopes.This study showed that the change of slope position significantly affected the differences in soil properties,therefore affecting the spatial distribution of soil microbial biomass.However soil microbial biomass was also affected by herbal richness with a negative effect,with which the combined effects led to no significant difference of soil microbial biomass among slope positions.