Ecological integrity varies with latitude due to the influence of climate and other factors. However, the relationship between ecological integrity and latitude and the driving mechanisms behind it remain poorly understood. Understand the driving mechanisms behind is of great significance to biodiversity conservation and ecological sustainability. In our study, we used an averaging approach and a threshold approach to quantify ecological integrity at different spatial scales. We map patterns of ecological integrity at different scales and their relationship with latitude. We investigate the roles of environmental temperature in shaping latitudinal patterns of forest ecological integrity. The results reveal a significant negative correlation between forest ecological integrity and increasing latitude at different spatial scales. We find that forest ecological exponentially with environmental temperature as predicted by the Metabolic theory of ecology (MTE), although other factors can also have impact on forest ecological integrity, such as topography, soil and human disturbance. Our study quantified the ecological integrity of forests at different scales in Northeast China and explored their latitudinal patterns. We find that the latitudinal patterns of forest ecological integrity can be explained by the metabolic theory of ecology. Ecological integrity is primarily driven by climate and other factors can also have impact on forest ecological integrity, such as topography, soil and human disturbance. And more importantly, our study extends MTE theory from the individual level to the ecosystem level, which is of great significance for forest conservation, management and restoration of integrity in the future.

The variation of species composition among communities, commonly known as beta diversity, is at the heart of ecology because of its role in explaining community assembly. This study presents a new approach that integrates functional and phylogenetic characteristics into the traditional beta diversity framework. Drawing on the observations from a large-scale forest inventory network, our results show that functional- and phylogenetic-based metrics offer distinct insights beyond those provided by species-based metrics. Species-based metrics help to identify species with specific distribution and locations with unique composition. Functional and phylogenetic-based metrics aid in identifying species and locations with distinctive ecological and evolutionary attributes. Furthermore, upon integrating functional and phylogenetic information, the relative contribution of deterministic processes in driving biodiversity patterns become more apparent. Our expanded framework provides a new opportunity to characterize the ecological uniqueness of species and locations, helping to reveal more detailed insights into assembly processes and guide biodiversity conservation.