Effects of Monovegetation Restoration Types on Soil Water Distribution and Balance on a Hillslope in Northern Loess Plateau of China

Abstract

In the Loess Plateau of China, mosaic-vegetation restoration by converting cropland into fallow (to regenerate natural vegetations) and perennials performs well in soil erosion control. However, soil desiccation caused by the planted perennials threatens the sustainability of vegetation restoration. Understanding of soil water distribution and balance in monovegetation systems at hillslope scale is crucial for building a constructive mosaic-vegetation restoration pattern in the Northern Loess Plateau. The objectives in this study were to investigate effects of monovegetation restoration types on soil water distribution and balance and discuss the possible implications of the monovegetation hydrological properties for mosaic-vegetation pattern establishment at hillslope scale. In 2004, the authors chose a one-piece waste hillslope with uniform slope of 12° and established four monovegetation plots subjected to shrub, grass, fallow, and cropland. Shrub, grass, and fallow are the typical vegetation restoration types, whereas cropland presents the traditional land use. Soil water content profiles, down to 400–600 cm depth, along the hillslope were measured with a neutron moisture meter from May–October in 2004, 2008, and 2009. Results showed that the rainfall infiltration depth was approximately 100 cm for shrub and grass but exceeded 300 cm for fallow and cropland. Six growth years later, shrub, grass, and fallow depleted more soil water than cropland, in the amount of 288, 313, and 62 mm, respectively. Soil water depletion in shrub and grass resulted in dried soil layers at the depth of 100–260 cm and 100–360 cm. Water balance results indicated that soil water deficit occurred in June during the rain season. The authors observed that downhill-accumulation of soil water storage, down to 400 cm depth, existed for fallow and cropland in 2004 and 2009. However, 6 growth years of shrub and grass substantially weakened such soil water downhill-accumulation tendency. This fact alone suggests that a mosaic vegetation system of planting shrub/grass downhill and setting fallow uphill would be appropriate from a standpoint of maintaining the sustainable development of vegetation restoration in the study area. Further experiments should be performed to develop the mosaic-vegetation patterns meeting the interests of both erosion control and sustainability of vegetation restoration.