Permeation theory is an important theory in physics. It refers to that when the density of a certain medium reaches a certain level (threshold), the permeable substance suddenly passes through the medium to reach another direction, which is called critical threshold phenomenon in physics. Later, the research methods, research concepts and research ideas were introduced into the research of landscape ecology. During the ecological planning of urban green space, when the density and area proportion of the patches that are suitable for good ecological environment reach the minimum threshold of the demand for the spread distance of biological species, these patches can assume the function of free migration between species. For example, when the rural landscape has reached a certain level of transformation by human activities, it has evolved into the urban landscape. The application of infiltration theory to the study of the critical threshold characteristics of landscape ecological flow and the relationship between landscape connectivity and ecological processes has become a landscape model. Because its infiltration theory has obvious threshold characteristics, it can be used to study the relationship between "landscape process and landscape pattern" in landscape ecological pattern.
Edited and Translated by Zhang Yifei