Evaluation of soil fertility in the succession of karst rocky desertification using principal component analysis.

Expanding of karst rocky desertification (RD) area in southwestern China has led to destructed ecosystem and local economic development lagging behind. It is important to understand the soil fertility at RD regions for the sustainable management of karst lands. The effects of the succession of RD on soil fertility were studied by investigating the stands and analyzing the soil samples with different RD grades in the central Hunan province, China, using the principal component analysis method. The results showed that the succession of RD had different impacts on soil fertility indicators. The changing trend of total organic carbon (TOC), total nitrogen (TN), available phosphorous (AP), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) out of 19 selected indicators in different RD regions was: potential RD (PRD)>light RD (LRD)>moderate RD (MRD)>intensive RD (IRD), whereas the changing trend of other indicators was not entirely consistent with the succession of RD. The degradation trend of soil fertility was basically parallel to the aggravation of RD, and the strength of integrated soil fertility was in the order of PRD>MRD>LRD>IRD. The TOC, total phosphorus (TP), cation exchange capacity (CEC), MBC, MBN, microbial mass phosphorous (MBP), and bulk density (BD) could be regarded as the key indicators to evaluate the soil fertility due to their close correlations to the integrated fertility. [ABSTRACT FROM AUTHOR]