The Forest Community Structure And Diversity Of 15hm~2 Dynamics Plot In Hubei Mulinzi Nature Reserve

The subtropical evergreen and deciduous broad-leaved mixed forest is a vegetation type jointly predominated by the forest canopy evergreen and deciduous species, formed by varying degrees of ingredients of fallen leaves caused by subtropical evergreen broad-leaved forest to adapt to the low-temperature environment at the northern latitude or a high elevation. Located in the middle mountain section of northeastern region of Wuling Mountain in the northern subtropical zone in the mountainous region of southwest Hubei, Hubei Mulinzi National Nature Reserve is one of the best-reserved areas of subtropical evergreen and deciduous broad-leaved mixed forest. However, no systematic research has been carried out on community structure, dynamics based on forest dynamics plot, spatial heterogeneity of environmental factors, spatial distribution pattern and relevance of dominant species and diversity etc. in this area. This work relies on national identity forest ecosystem research station in Hubei Enshi, and the 15 hm2 forest dynamics monitoring plot in accordance with the standards and technical specifications of CTFS was established in Mulinzi Nature Reserve in 2013. The characteristics of structure and diversity of subtropical evergreen and deciduous broad-leaved mixed forest were studied based on the first monitoring data about woody plant individuals and environments in the 15 hm2 forest dynamics plot (FDP) following the Chinese Forest Biodiversity Monitoring Network investigation and research methods. The results showed as the following:1. The constrained clustering analysis was used to classify topographic and edaphic factors by taking 20 mx20 m plots as space units in the forest dynamics plot, and the findings presented the three types of habitats:ridge, slope field and valley had the great spatial heterogeneity. Within the forest dynamics plot, soil is low in pH and abundant in OM, TN, AN, and AK, but AP and TP are insufficient. The enrichment degree of edaphic factors, spatial pattern, spatial correlation and variation features were noticeable in the forest dynamics plot.2. There were a total of 228 types of woody species and 84,189 individual plants which belong to 61 families and 112 genera in Mulinzi forest dynamics plot. These plants showed the old origin of species, abundant primitive components and rich single-species and few-species in flora composition, and had distinct temperate plant genera as well as transitivity of abundant tropical elements. The major families are theaceae and fagaceae for species composition. Low density species was the predominated species composition in the forest dynamics plot, which account for 49.56% of all species, and the sprouting species account for 60.1% of all species.3. Both the species richness and individual abundance gradually decreased with the increase of height and diameter class in Mulinzi forest dynamics plot. The dynamic tendencies of dominant species fall into 4 types, such as increasing population, recent stabilizing and future declining population, declining population, and population increasing and declining alternatively. The structural characteristics of most dominant species revealed that they had good regeneration, and the whole community was in the progressive succession process. The spatial distribution pattern of the majority of dominant species in the forest dynamics plot exhibited a clustering distribution on a certain scale, but the clustering strength gradually deceased with the increase of research scale.4. The functional diversity of species within the community changed with spatial scale and habitat conditions. The functional richness significantly increased with the increase of scale, while the functional evenness decreased with the increase of scale; the functional divergence, functional dispersion and Rao’s quadratic entropy were different at different scales. From the ridge to valley, both the functional evenness and functional divergence were increasing while the functional dispersion and Rao’s quadratic entropy significantly decreased for different habitat types. There was no obvious difference in functional richness. The phylogenetic diversity of the community species in Mulinzi forest dynamics plot significantly increased with the increase of sampling scale and was highly related to the species abundance; however, the phylogenetic diversity did not show apparent difference in various habitat conditions.5. The inter-species interaction changeed accordingly with the spatial scale change and habitat conditions in Mulinzi forest dynamics plot. The competitive effect became more popular than the facilitation with the increase in research scale. The importance and strength of competitive effect were higher than those facilitation in the ravine and ridge, and the strength of community inter-species interaction in the ridge was the highest and more widespread.