Research On The Evolution Mechanism Of Landscape Pattern Based On "source-sink" Landscape Theory

Due to reveal ecological processes,the driving mechanism of ecological patterns is a hot topic and difficult issue in the field of ecology.How to effectively combine ecological landscape pattern and ecological processes is the key to interpret the evolution mechanism of ecological landscape pattern,which is important for rational regulation of ecosystem structure.The"Source-sink"can express the genesis and destruction of some object:the"source"can promote some object generation,while the"sink"can inhibit that.As a result,using the"source–sink"theory in the ecological processes is an effective method to combine the ecological landscape patterns and ecological processes,which provides possibility to interpret the driving mechanism of ecological process.Land use and cover change(LUCC)expresses the process of interaction between human and nature during various development stages.For the ecological landscape with significant human activity,the way and level of LUCC affect the ecosystem structure under different scales.Ecosystem structure decides the ecological function,as a result,the ecosystem structure function decided by ecosystem structure change with the ecosystem structure.Obviously,the effection of different land use types on ecological processes is different,including inhiti and pormote the ecological processes.For some specific ecological processes,the land use types promoting the process are identified as"source"landscape,while those inhibitting the process are identified as"sink"landscape.Therefore,"source-sink"landscape not only expresses the characteristics of ecological landscape,but also the connotation of ecological processes,based on which,we carried out ecological landscape pattern analysis and studied the driving mechannism of ecological processes by identifying the"source–sink"landscape pattern.At last,the model of ecological landscape evolution mechanism is built,which is a sets of models including the identification of"source–sink"landscape,landscape pattern analysis,driving mechanism of ecological processes with"source–sink"landscape as driving factors and associated characteristics of across–scales.In this work,taking Guiyang City with significant human activities as an example and using datasets including land use data since 1990 indicating ecosystem structure,the data of annual mean temperature and annual precipitation since 1980indicating climate maintenance function,and total NPP data since 2000 indicating primary productivity supply,on the level of Guiyang City scale and the level of all the unit of jurisdictions including Municipal district,Kaiyang,Qingzhen(county-level cities),Xifeng county and Xiuwen county,the charateristics of ecosystem structure and function,the identifying of the"source-sink"landscape and its characteristics,the driving mechanism of ecological process with"source-sink"landscape as driving factors and the relationship of across–scales were studied,and the model of regional ecological landscape pattern evolution mechanism is built finally by the methods of mathematical statistics and linear regression fitting.The results showed that:1)Different land use types have different effect on ecological processes,the construcion land is"source"landscape,while,most the cultivated land and forest land and a few grassland are"sink"landscape.The"source-sink"landscape is different from ecological processes and scales.The"source-sink"landscape effect of thermal process is more significant than that of water process.On the city scale,the"sink"landscape of thermal process was cultivated land and forest land,and the correlation coefficient between the change rate of temperature and"sink"landscape ranged from-0.64 to-0.94.The is construction land,and the correlation coefficient between the change rate of temperature and"source"landscape ranged from 0.71 to 0.98.On the county scale,the"source"landscapes of the thermal process were all the construction land of each unit of Guiyang City,and the correlation coefficient between the change rate of temperature and"source"landscape ranged from 0.67 to 0.99.On the county scale,the"sink"landscapes were complex and different for thermal processes around Guiyang.2)There was a balance relationship between"source"and"sink"landscape area in time and space,and"source–sink"landscape has a rise"source",decline"sink"trend and a decline concentration trend with time.With time,the"source-sink"balance ratio on city scale was-1.56,on the county scale they were-1.73,-1.31 and-1.59,respectively,the average value of which was about equal to that of the city scale.Gini coefficient of"source-sink"landscape indicated that the distribution concentration of"source-sink"landscape is different,which showed that the distribution of"source"landscape is more concentrated than that of"sink"landscape.The Gini coefficients of the"source-sink"landscape of the thermal process were all>0.3 and decreased over time,which indicated that the degree of concentration was alleviated,especially after 2010.3)The driving models are bilut with"source-sink"landscape as driving factors.The driving models of thermal were roughly divided into two types,that was the driving factors of thermal process changing or not with scale transformation.The first type included kaiyang Station which driving factors did not change with scale transformation;however,the driving factors changed for Guiang and Qingzhen Station.The driving mechanism of all the stations as follow.The dt,dx₁ and dx₂ were change rate of temperature,"sink"area and"source"area,respectively.Only the water process of Xifeng and Xiuwen Station had significant driving model,and the driving mechanisms as follow.The d P,dx₁ and dx₂ were change rate of temperature,"sink"area and"source"area,respectively.4)When the low-level scale(county scale)transformed to the high-level scale(city scale),the degree of"source-sink"landscape change determined the driving factors of the ecological process model changing or not.If the"source"landscape was same,the change of"sink"landscape caused by scale transformation less than 1 did not lead to the change of the influencing factors of ecological process,however,if the scale transformation results in a large change of"sink"landscape(more than 1),the impact factors of the ecological process model would change.Based on series of studies including the identification of"source-sink"landscape,the analysis of"source-sink"landscape pattern,driving research of ecological processes with"source-sink"landscape as affect factors and cross-scale correlation characteristics on the city and county scales,the evolution mechanism of ecological landscape pattern was built with the relationship of human activities,the change of source-sink landscape pattern and ecological processes on different scale as the main content.When human beings perform ecological restoration and transform the underlying surface according to specific ecological purposes(such as controlling warming and regulating NPP,etc.),the change mechanism of"source-sink"landscape pattern can provide a scientific basis for guide how to transforme the underlying surface and assessing its corresponding ecological impact.The way of"Source-sink"effectively solved the prolblem combining the landscape pattern index and ecological process,but because only Guiyang City and the basic structural ecological function were used as objects,the commonality of scale transformation correlation needs to be further verified.Meanwhile,the lag effect and heterogeneity of impact of LUCC on ecosystem function need further accurate,so that the pattern evolution mechanism based on"source-sink"landscape can be further improved.