Studies On Ecosystem Pattern And Dynamics In Kunming Based On Remote Sensing

Ecosystem classification system of Kunming were established based on ecosystem structure,features,and functioning.Landsat TM imageries from 1990 to 2015 at 5-years interval were derived to study ecosystem structure,pattern,dynamic changes and its driving agents,by applying remote sensing and geographic information system technology.The results would be helpful for implementation of ecological protection and management.The results showed that:(1)According to ecosystem features,structure and functional features,Kunming ecosystems were divided into 8 types at the first class,15 types at second class,25 types at third class,and 34 types at fourth class.Forest ecosystems and agro-ecosystems were dominant,which accounting for 34.77%and 33.24%respectively.Warm temperate coniferous forests and semi-humid evergreen broad-leaved forests were dominant types in forest ecosystems.Rainfed land was the main type in agro-ecosystems.Semi-natural shrubland and grassland with shrubs had second large area.Among the current ecosystem types,broad-leaved forests,coniferous forests,shrub land and grassland with shrubs were accounting for 60%of the total area,indicating that natural ecosystems were still the main part.(2)In the ecological system of each county,forest ecosystem and agro-ecosystems were the main ecosystem in almost districts.Shrubland was occupied a large proportion in Shilin,grassland with shrubs was occupied a large proportion in Dongchuan,urban ecosystem had the largest area in five urban districts.(3)During the study period,the area of the settlement increased continuously,and the area of broad-leaved forests,coniferous forests,shrublands,grassland with shrubs,and farmlands were decreased,and the area of farmland decreased mostly.Broad-leaved forests,coniferous forests,shrubs and grassland with shrubs were decreased from 1990to 2000,but increased from 2000 to 2015.And farmland area was changed in an opposite way during the same peroid.The area of construction land was increased by 1051.94km~2.(4)During the year from 1990 to 2000,the area of broad-leaved forests and coniferous forests was reduced,mainly conversed into farmlands.The area of broad-leaved forests from 2000 to 2015 was increased,mainly transformed from shrublands,grassland with shrubs.Shrubs grassland and farmland transformed into each other in the two periods.During the year from 1990 to 2000,shrubs and shrubs were converted into farmland,and the year from 2000 to 2015 were changed back to each other.The area of settlement increased continuously,mainly transformed from farmlands.During the study period,change rate of each type decreased gradually.The disturbance of human to natural ecosystem became weak gradually,and the transformation of artificial ecosystem was strengthened.(5)In term of ecosystem characteristics,the year of 2000 was the turning point of landscape metrics.At the landscape level,the overall landscape heterogeneity of Kunming ecosystem was enhanced,exchanges of material,energy,and information between patches was reduced.The area of the internal habitat was reduced,material,corridor of energy and species were cut off,and patches were isolated.At the class level,the area of broad-leaved and coniferous forests was reduced.Although the corridors of material,energy,and species exchange were cut off and patches are isolated,while the exchange,of material energy,and species between patches became frequent.Shrubs and shrubs grassland are similar to the farmland,and the material,ability and information between the same types of patches reduced,the habitat area was reduced,and corridors for material,energy and species exchange were cut off,and patches are isolated.(6)Ecosystem change in Kunming was mainly controlled by human factors.From1990 to 2005,policy factors were the main controlling factors.From 2005 to 2015,urbanization and transportation development became the key factors.In addition,demographic growth and economic development were the inevitable factors in development of human society,and have played an important role in the past 25 years.