Abstract:

Aims Soil quality plays an essential role in vegetation restoration in the karst soil ecosystem. Many studies have reported soil quality of different plantations and vegetation successional stages in karst regions, but few have focused on the seasonal dynamics of basic soil properties. Our objectives were to investigate annual dynamics of basic soil properties of different types of plantations and evaluate soil integrated quality index (SQI).
Methods We analyzed the dynamics of soil physical and chemical properties and soil enzyme activities for four sites in Puding County, Guizhou Province, China: Robinia pseudoacacia plantation (RP), Cupressus duclouxiana plantation (CD), R. pseudoacacia-C. duclouxiana mixed plantation (RD) and a non-plantation area (CK). Soil samples were collected in alternate months from September 2009 to September 2010. Soil factors were measured using general methods, and data were analyzed using SPSS 13.0 software.
Important findings Soil physical properties of all three plantations had an advantage over the non-plantation area and were slightly improved within one year. There were significant differences in soil nutrients and soil pH among the four sites (p < 0.01). Soil urease activity in all sites was highest in September and lowest in January. Soil invertase activities were remarkably different among the four sites (p < 0.01). Soil catalase activity exhibited a unimodal peak, and alkaline phosphatase activity had a bimodal peak. Soil polyphenoloxidase activity was lowest in January and very low in RP throughout the study. Moreover, the rank of means of five soil enzyme activities was different among the four sites. The SQI of RP, CD, RD and CK was 0.748, 0.406, 0.590 and 0.315, respectively. In general, all three types of plantations, but especially RP and RD, could improve soil quality after conversion of farmland to forest.

Key words: comprehensive evaluation, karst region, plantation, rocky desertification site, soil enzyme activity