Source-sink landscape theory and its ecological significance

Exploring the relationships between landscape pattern and ecological processes is the key topic of landscape ecology,for which,a large number of indices as well as landscape pattern analysis model were developed.However,one problem faced by landscape ecologists is that it is hard to link the landscape indices with a specific ecological process.Linking landscape pattern and ecological processes has become a challenge for landscape ecologists.“Source”and“sink”are common concepts used in air pollution research,by which the movement direction and pattern of different pollutants in air can be clearly identified.In fact,for any ecological process,the research can be considered as a balance between the source and the sink in space.Thus,the concepts of“source”and“sink”could be implemented to the research of landscape pattern and ecological processes.In this paper,a theory of sourcesink landscape was proposed,which include:(1)In the research of landscape pattern and ecological process,all landscape types can be divided into two groups,“source”landscape and“sink”landscape.“Source”landscape contributes positively to the ecological process,while“sink”landscape is unhelpful to the ecological process.(2)Both landscapes are recognized with regard to the specific ecological process.“Source”landscape in a target ecological process may change into a“sink”landscape as in another ecological process.Therefore,the ecological process should be determined before“source”or“sink”landscape were defined.(3)The key point to distinguish“source”landscape from“sink”landscape is to quantify the effect of landscape on ecological process.The positive effect is made by“source”landscape,and the negative effect by“sink”landscape.(4)For the same ecological process,the contribution of“source”landscapes may vary,and it is the same to the“sink”landscapes.It is required to determine the weight of each landscape type on ecological processes.(5)The sourcesink principle can be applied to non-point source pollution control,biologic diversity protection,urban heat island effect mitigation,etc.However,the landscape evaluation models need to be calibrated respectively,because different ecological processes correspond with different source-sink landscapes and evaluation models for the different study areas.This theory is helpful to further study landscape pattern and ecological process,and offers a basis for new landscape index design.