Quantifying the hazardous impacts of human-induced land degradation on terrestrial ecosystems: a case study of karst areas of south China

This paper assesses the harm that human-induced land degradation poses on terrestrial ecosystems. We propose and define a hazardous impact (HI) indicator and a method to quantify this degradation and promote sustainable land use under the pressure resulting from population growth. Taking human appropriation of the net primary productivity owing to land-use conversion (HANPP(luc)) as a proxy, the quantification of HI was developed with support from remotely sensed net primary productivity (NPP) data and using the co-kriging method. A case study in the karst area of south China showed that HI in the study area decreased from southwest to northeast. Areas with the highest level of HI occupied 4.77 % of the total area and were distributed in northwest Sichuan Province, southwest Yunnan Province, and southern Guangxi Autonomous Region. Lower HI areas were mainly located in Hunan Province and Hubei Province. This indicates that land use has a strong impact on karst rocky desertification. To maintain a decreasing trend in HI, a land-use policy must guide human activity. In the karst areas of south China, HI and rocky desertification have similar spatial distribution and intensity. This suggests that HI can effectively reveal adverse effects on the ecosystem due to human-induced land degradation, and that it can potentially be applied to other related issues. We also argue that NPP reduction and HI level do not follow a simple 1: 1 relationship, so revisions may be needed when applying the proposed indicator and approach to other regions. This approach also needs to be improved in its accuracy in terms of natural vegetation extraction.