Review on the shelter forest decline

Forest decline is one of the critical environmental issues in the 21st century,while the shelter forest in China,which occupies 31% of the China's total forest area,is partly declined seriously.Based on the literature review,the shelter forest decline was defined as the reduction of shelter forest function and efficiency due to the decline of forest productivity and soil fertility and the irrational stand structure.The major causes of shelter forest decline such as no matching tree species with site,irrational stand structure,lacking in rational management,human disturbances,and frequent natural disturbances were summarized.The main existing problems in the researches on China's shelter forests were analyzed from the aspects of decline mechanism,stand structure,management,human disturbancs,and species composition.It was suggested that the studies on the process and mechanism of shelter forest decline,the early diagnosis and evaluation as well as the prevention of the decline,the macro-scale arrangement of shelter forest,and the strategies for responding disturbances should be further studied.