Quantifying the effectiveness of ecological restoration projects on long-term vegetation dynamics in the karst regions of Southwest China

Abstract

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 proposes 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. The distribution is however not homogeneous and counties with a high project effectiveness in spite of complex natural conditions were identified, but also counties with negative vegetation trends despite favorable conditions and high investments. 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.

Increased vegetation growth and carbon stock in China karst via ecological engineering

“…Although this study found a clear pattern at the county level, finer-scaled studies and in situ measurements are necessary to support the surveillance of environmental projects. It has been shown that financial investment and the spatial extent of plantations for environmental restoration or commercial purposes are not linearly linked with an increase in the vegetation abundance, as the effectiveness of implementations varies with topography and management aspects 15 . Whereas the satellite-based data applied were able to monitor continuous changes in LAI and ABC, no firm conclusions on changes in species composition and functioning can be drawn and the positive trends may conceal the establishment of monocultures and inappropriate conservation actions.…”

“…As the effectiveness of the implemented conservation varies considerably between counties, this will also be reflected in the afforestation or land cover changes 15 . However, the data provide a useful indication on active investments that allows for a detailed analysis of vegetation changes in relation to conservation project efforts.…”

“…Dynamic vegetation models and Earth observation studies reveal climatic and atmospheric changes as the main drivers of large scale increases in LAI 10,13 . On the contrary, the anthropogenic footprint is usually found to cause land degradation and deforestation 13,14 , and only a few studies find a direct positive effect of management on vegetation cover and biomass trends 2,11,15 . Although ecological conservation projects aim at increasing biodiversity, carbon sequestration and vegetation cover 16,17 , the success of such conservation efforts is not easily quantifiable, and the spatial footprint of projects is not always commensurable with contemporary satellite-and modelling-based monitoring methods.…”

Conversion of Blue Water into Green Water for Improving Utilization Ratio of Water Resources in Degraded Karst Areas

“…In China, deforestation had brought about large-scale rocky desertification in karst regions during the period of the "Great Leap Forward" (1958)(1959)(1960)(1961). According to statistics, in Guizhou Province alone where there are large number of karst regions [19,25], the area of rocky desertification expanded considerably by 3.76 times from 1970 to 2005 [26]. Based on a study in Guizhou Province, Wang et al (2004) [27] found that vegetation deterioration, soil loss, and outcropping of rocks led to serious water shortages (local permeability coefficients are commonly 0.3-0.6).…”

“…By establishing the "water resources allocation" model and calculations, Song et al (2015) [42] believed that a large number of water diversion from the west part of Guizhou province to its central part would be beneficial to the ecological restoration in central of Guizhou. Tong et al (2016) [25] argued that limited by a low water use efficiency, the ecological recovery effect in southwest of China was questionable. Although these researchers performed thorough analyses of water resource utilization from the perspective of ecological restoration in degraded karst areas, and some even calculated the ecological water volume for evaluation and analysis via numerical simulation, they did not clarify how to improve the ecological water share.…”