Spatial distribution of precipitation extremum in the ecotone between agriculture and animal husbandry in northern China
北方农牧交错带降水极值变化空间特征

The ecotone between agriculture and animal husbandry in northern China is the fra-gile zone of ecological environment.Changes of rainfall extreme s will have tremendous influ ence on agriculture and animal husbandry.Daily rainfall amount of109weather stations from1971to1998is used to analyze the annual change and spatial distribution of rainfall extremes in the e-cotone between agriculture and animal husbandry in northern China.The rainfall extremes com-prise five parameters of annual rainfall,annual erosive rainfall,annual erosive rainfall days,an-nual rainstorm,and annual rainstorm days.The result shows that annual average erosive rainfall is between3.5and17.6days and rainstorm is between0and2.6days.Annual rainfall,erosive rainfall and rainstorm have increased gradually in recent 30years in most parts of the ecotone between agriculture and animal husbandry in northern China,and the annual rainstorm and ero-sive rainfall have increased more quickly than annual rainfall which shows that the rainfall in-tensity has increased and the potential erosion capability of rainfall has enhanced in most parts.The areas of positive change trend center in Chifeng and Tongliao of Inner Mongolia,Wuzhai in Shanxi province,and Yanchi in Ningxia Hui Autonomous Region.The rainfall extremums have deceased in only some areas and the areas of negative change trend center in Xixian county of Shanxi province and Luochuan in Shaanxi province.