Abstract: The mutually beneficial interactions between plants and pollinators or seed dispersers have a significant consequence in the maintenance of biodiversity. The mutualistic interactions often involve dozens or even hundreds of species that form interdependently complex networks. Recent improvements in network analysis provide suitable means for the researches on the structure of the complex ecological networks. The mutualistic networks have the following characteristics: (1) with the structural characteristic of nestedness, which introduces functional redundancy, (2) with asymmetry in the numbers and strengths of interactions, which facilitates the maintenance of biodiversity, and (3) with the characteristic of modularity. The species between modules interact with each other more loosely than those within modules. Of the factors affecting plantanimal mutualistic networks, habitat fragmentation and invasive species are the two especially obvious factors. Habitat fragmentation hampers the interaction of mutualism, reducing the potential of plant regeneration, while invasive species are mainly represented as alien plant invasion, competing with native plants for the mutualistic interactions with animals. In contrast with native plants, alien plants are interrelated with native generalists more easily. The plantanimal mutualistic interactions in communities can be changed with time and space. Accordingly, how and why these changes happened should be further approached in the future.

Key words: soil property, afforestation areas., soil fertility