Characteristics Of Land Use Change And Effects Of Land Management Practices On Dynamics Of Soil Water, Nutrients And Organic Carbon In Mountain Landscapes, Southwestern China

Land use change is one of the primary causes of global environmental change, and has caused many concerns of global change researches. But, the questions of what the trajectories of land use change and which measures mitigate environmental issues resulted from corresponding land use change remain largely unanswered. Despite that various results in understanding land use change have been achieved, most published cannot figure the concrete trajectories of land use change, and scale-dependence of land use change cannot be resolved as well. In China, several major land use change projects have been initiated in recent two decade. However, most of them have mainly focused on the North-East, South-East and North regions of China. Few studies of land use change have paid more attention to southwestern mountainous areas, China, particularly in Chongqing. Certainly, land use change inevitably results in certain ecological and social effects. Moreover, shock events will occur, when the concentration of these effects are excessive eco-environmental threshold. Currently, appropriate land management practices have universally considered that provide alternative methods for managing slopeland soil water and paddy soil nutrients and organic carbon. For slopeland soil water, more interests were made in arid, semi-arid or semi-humid regions. As for soil nutrients and organic carbon, dry farming land soils or the effects of different function land transformation or short-term and single soil management practices on them were focused on. Little is known about, at a microcosmic cultivation scale, long-term effects of land management practices on hilly slopeland soil water in humid regions, and soil nutrients and organic carbon in paddy regions. Furthermore, under the background of regional land use change, the effects of local land management practices on soil water, nutrients and organic carbon are even more poorly understood.The goal of this study is to identify the trajectories of changes in land use, measure different land management practice effects on soil water, nutrients and organic carbon, and develop proper land use scenario and recommend appropriate management practices in mountain landscapes, southwestern China. The study included two components, i.e., land transformation to a different function and effects of land modification within a function on soil water, nutrients and organic carbon. The former involved remote sensing data, statistics data and household interview data, while the latter used field or experiment monitoring data. For slopeland soil water, experimental plots were subject to the following treatments: Cross-sloping tillage (CST); Cross-sloping tillage with organic manure (CST/OM); Cross-sloping tillage with straw mulch (CST/SM); Contour ridge culture (CRC); Contour ridge culture with organic manure (CRC/OM); Contour ridge culture with straw mulch (CRC/SM). For paddy soil nutrients and organic carbon, four treatments, conventional tillage (rice (Oryza sativa L.)-fallow) (CT/RF), conventional tillage (rice-wheat (Triticum aestivum L.)) (CT/RW), no tillage and ridge culture (rice-fallow) (NTR/RF), and no tillage and ridge culture (rice-wheat) (NTR/RW) were used. The results indicated that:(1) In study site, land use change presented pronounced regional heterogeneity for two stages, regardless of the speed or direction of land transformation. The patches possessing about 18.37% and...