Abstract: Wetland not only provides rich production and living materials,but also has great environmental function and value.The LDI (Landscape Development Index) can be used as an indicator of the impact of human disturbance on the environment.In this paper,the wetland in the middle reaches of Heihe River was used as the object of research,and the land use classification map was interpreted based on the remotely sensed images in 1975,1987,1992,2000,2010 and 2016.By calculating the landscape pattern index and LDI index value of different types of wetlands in the past 41 years,the response of landscape pattern to human disturbance was analyzed.The results showed that the landscape pattern index of wetland has undergone great changes from 1975 to 2016.The area of natural wetlands,including the riverine wetland,lake wetland,riparian wetland and marsh wetland,kept declining,and the area of artificial wetland showed an increasing trend.The complexity of the wetland edge was intensified and the connectivity of wetland patches became poorer which meant the degree of fragmentation of the wetlands was enhanced.From the space perspective,the human disturbance mainly occurred along the river wetland and the flood plain,and the areas of high value included Ganzhou and Gaotai County.From the time perspective,the human disturbance to the natural wetlands was showing a trend from more to less and a contrary trend to the artificial wetlands.The wetlands were transformed into forest land,grassland,industrial and mining land and cultivated land because of human disturbance.The landscape pattern index has a strong correlation with the human disturbance.From 1975 to 2016,the response of the different types of wetland to the landscape pattern was different which was reflected by the fact that the reinforcement of human disturbance was the main reason for the decrease of river wetland areas.For the reservoir pond wetlands,with the increase of human disturbance,the patch areas were increased which made the edges of the wetlands become complicated,the fragmentation and landscape heterogeneity become more obvious.The correlation between the riparian wetland and the edge density was strong,reflecting the riparian wetland patch edge became more and more complex as the human activities got increased.

Key words: human disturbance, human activities, LDI index, wetlands in the middle reaches of Heihe River