Response of Soil Chemical and Microbial Properties to Vegetation Restoration on the Loess Plateau, China

Revegetation has been reported as one of the most effective measures for reducing soil erosion on the Loess Plateau in China. We evaluated the effect of natural revegetation restoration on soil chemical nutrient, microbial biomass and enzyme activities on the Loess Plateau of China. The vegetation types studied, in order from the shortest to the longest enclosure duration, were abandoned grazed grassland (Ab.G3, 3 years), Hierochloe odorata Beauv. (Hi.O7, 7 years) communities, Thymus mongolicus Ronnm (Th.M15, 15 years), Artemisia sacrorum Ledeb (At.S25, 25 years), Stipa bungeana Trin Ledeb (St.B36, 36 years), and Stipa grandis P. Smirn (St.G56, 56 years). The results showed that soil organic carbon (SOC) and total nitrogen (N) was 9.2-32.2 and 1.2-3.5 g/kg during vegetation restoration, respectively. Except from Th.M15, SOC and total N increased with restoration time. Also, soil microbial biomass carbon (Cmic), phosphorus (Pmic), invertase activities, and alkaline phosphatase activities increased with restoration time. Whereas, soil microbial biomass nitrogen (Nmic) and urease activity was the highest in the early succession period and lowest in the mid succession period (under Th.M15 and At.S25). Revegetation resulted in more abundant and stable soil ecological environment by enhancing soil nutrients and biological properties. Thus, this is a beneficial measure for the recovery of degraded soils on the Loess Plateau of China.