Exploring and revealing the mechanisms of community construction (niche theory and neutral theory) is a hot topic and a difficulty in ecology and biogeography research. Studies on the relationship between beta diversity and spatial distance and natural distance provide some theoretical basis for the construction of the community. However, studies on beta diversity have mainly been focus on species differences and little on differences in the evolutionary relationships and functional properties between species. Based on field investigations, we evaluated the two-element attribute data of the total species, that is when the species was in the stands, it was denoted as 1 and when it was not in the stands, it was denoted as 0. We developed a master plant list of seed species found in the middle and upper reaches of the Fenhe River. According to the Linnaean classification system, the species were divided into six levels: Phylum, Class, Order, Family, Genus, and Species, and the phylogenetic trees of all species were built. Considering the plant morphology, physiology, and breeding phenology, plant properties including growth form, life history of plants, types of nitrogen fixation, photosynthetic pathway, light tolerance, leaf shape, flower shape, pollination mode, fruit type, seed dispersal mode, flowering time, flowering phase, fruit time, and fruit phase, were recorded to measure functional diversity and to express differences between individual plants in terms of productivity, resource utilization, ecological resilience, and ecological countermeasures. The measurement indicator, beta diversity, was calculated using the Jaccard index. The Tβ, Pβ, and Fβ diversity patterns of 17 stands in the middle and upper reaches of the Fenhe River were calculated, respectively, and the correlations among diversity patterns, spatial distance, and habitat heterogeneity were analyzed. The results showed that (1) with increasing distance of the 17 stands, the Tβ, Pβ, and Fβ patterns showed an increasing trend, that is, the distance of the community showed an attenuation effect. (2) TP (total phosphorus) is the main soil factor that influences the Tβ, Pβ, and Fβ in the sample areas (P < 0.05), while the influence of pH, TOC (total organic carbon), and TN (total nitrogen) was not significant (P > 0.05). (3) Because of the restrictions on spatial diffusion and the influence of habitat heterogeneity, the diversity of beta diversity among the samples was obviously different (Tβ 0.66-1, Pβ 0.42-0.85, and Fβ 0.51-0.94). (4) Although the Tβ, Pβ, and Fβ reflected different aspects of diversity, the relationship with each other was highly significant (P < 0.01). (5) Based on the Tβ, Pβ, and Fβ diversity patterns and their relationship with spatial distance and habitat heterogeneity, it is suggested that the environmental factors and diffusion limitation jointly dominated the pattern of beta diversity, namely, the construction mechanism of the community was jointly decided by the ecological niche theory and neutral theory.