Qiaoling Yan?Jiaojun Zhu?Xiao Zheng?Changjie Jin

Causal effects of shelter forests and water factors on desertification control during 2000–2010 at the Horqin Sandy Land region,China

Qiaoling Yan?Jiaojun Zhu?Xiao Zheng?Changjie Jin

The Horqin Sandy Land(HSL),the largestsandy land in the semi-arid agro-pastoral ecotone of Northeast China,has been subject to desertification during the past century.In response,and to control the desertification, government implemented the Three-North Shelter/Protective ForestProgram,world’slargestecologicalreforestation/ afforestation restoration program.The program began in 1978 and will continue for 75 years until 2050.Understanding the dynamics of desertification and its driving forces is a precondition for controlling desertification. However,there is little evidence to directly link causal effectswith desertification process(i.e.,on thechanging area ofsandy land)because desertification is a complex process, that can be affected by vegetation(including vegetation coverand extentofshelterforests)and waterfactorssuch as precipitation,surface soilmoisture,and evapotranspiration. The objectives ofthis study were to identify how influencing factors,especially shelter forests,affected desertification in HSL over a recent decade.We used Landsat TM imagery analysis and path analysis to identify the effects of spatiotemporalchangesin waterand vegetation parametersduring 2000–2010.Desertification was controlled during the studyperiod,as indicated by a decrease in desertarea ata rate of 163.3 km2year-1and an increase in the area with reduced intensity orextentofdesertification.Totalvegetation cover in HSL increased by 10.6%during the study period and this factor exerted the greatest direct and indirect effects on slowing desertification.The contribution oftotalvegetation cover to controlling desertification increased with the intensity ofdesertification.On slightly and extremely severe desertified areas,vegetation covercontributed 5 and 42%of the desertification reduction,respectively.There were significant correlations between total vegetation cover and waterconditions(i.e.,evapotranspiration and precipitation) and the area ofshelterforests(P