Biological Indicator of Soil Quality:A Review

Current findings of the study on use soil microorganism,soil enzymatic activity and soil animals as biological indicators of soil quality are here in summarized and reviewed. Soil microbe is the most active part of soil organic constituents and ecosystem,and hence considered to be the most sensitive biological indicator of soil quality. Soil microbial biomass stands for quantity of the microorganisms that regulate energy and nutrient cycle in soil and transformation organisms,however,it is essential to combine this with the study on microbial diversity to make up the shortage that it fails to reflect composition of the soil microorganisms and variation of the microbiota. Dynamics of composition and diversity of the soil microbial community reflects variability of soil biological groups and variation of quantity and functions of soil microorganisms with soil quality. Soil microbial activity displays itself in microbial quotient,microbial respiration and metabolic quotient. The relationship of the size of biomass with activities of microbial groups should be taken into account as an indicator of differentiation between soil microbial groups. Soil enzymatic activity is an indicator extremely time-effective,and reflects nearly real-time change in soil quality. In the aspect of soil animals,species composition and population,relative abundance of soil fauna,diversity and activity are sensitive indicators of soil biological quality. Compared with physical and chemical indicators,biological indicators are more sensitive and quick in response to changes in soil quality,and hence more widely applied to soil quality evaluation nowadays.