Search

To alleviate the severe rocky desertification and improve the ecological degradation conditions in Southwest China, the national and local Chinese governments have implemented a series of Ecological Restoration Projects (ERPs) since the late 1990s. This study proposed a remote sensing based approach to evaluate the long-term efforts of the ERPs started in 2000. The method applies a time-series trend analysis of satellite based vegetation data corrected for climatic influences to reveal human induced vegetation changes. The improved residual method is combined with statistics on the invested project funds to derive an index, Project Effectiveness Index (PEI), measuring the project effectiveness at county scale. High effectiveness is detected in the Guangxi Province, moderate effectiveness in the Guizhou Province, and low and no effectiveness in the Yunnan Province. Successful implementations are closely related to the combined influences from climatic conditions and human management. The landforms of Peak Forest Plain and Peak Cluster Depression regions in the Guangxi Province are characterized by temperate climate with sufficient rainfall generally leading to a high effectiveness. For the karst regions of the Yunnan and Guizhou Provinces with rough terrain and lower rainfall combined with poor management practices (unsuitable species selection, low compensation rate for peasants), only low or even no effect of project implementations can be observed. However, the effectiveness distribution is not homogeneous and counties with high project effectiveness in spite of complex natural conditions were identified, while counties with negative vegetation trends despite relatively favorable conditions and high investments were also distinguished. The proposed framework is expected to be of high relevance in general monitoring of the successfulness of ecological conservation projects in relation to invested funds. [ABSTRACT FROM AUTHOR]

Estimating soil organic carbon (SOC) storage for soils with discontinuous distribution in the karst regions of southwest China poses a challenge due to the predominant carbonate bedrock. In addition, it is not clear how effective the ecological restoration and reconstruction policies, which have been conducted in this region since the 1990s, have been in terms of SOC sequestration. In this study, we explored the ability of an empirical model and validated it using field survey data to predict the coverage of discontinuous distribution soil in a karst region in southwest China. Employing the soil coverage map, survey data of SOC at a soil depth of 0–15 cm, and three land use/cover maps in 1990, 2004, and 2011, we estimated the changes of SOC storages in the study area. Results showed that the land use/cover changes induced by the implementation of ecological restoration policies promoted SOC storage in the karst region. The SOC storage increased from 2.34 Tg to 3.01 Tg and soil organic carbon density increased from 2.72 kg/m2to 3.50 kg/m2over the study period. The mountain closure policy, Grain for Green program, and migration program currently implemented in the karst region have contributed to a decline in the rate of SOC decomposition and the reduction of soil disturbance, which resulted in carbon sequestration in the global carbon cycle while also improving the ecologically fragile karst environment. SOC storage may have been overestimated by almost twofold while ignoring the discontinuous distribution features of soil cover in the karst region. However, along with an increase in both population and agricultural activities, SOC storage in the nonkarst area declined from 1990 to 2011. With the ecological restoration occurring in the karst area, losses of SOC induced by increased farming activities in the nonkarst area should not be ignored. [ABSTRACT FROM AUTHOR]