Spatial Distribution Patterns And Associations Of Tree Species In Spruce Secondary Forest Of Guandi Mountain

Plant species in forest community by its unique ecology and morphological properties, under the interaction with environmental factors, become the basic structure and function unit of forest ecosystem. The research of spatial patterns and correlation of forest communities is help for understanding the structural features of community and internal ecological processes. It’s meaningful to speculate future trends of population and know better forest community species diversity maintenance and coexistence mechanism. In this study, the research object is Guandi mountain spruce nature secondary forest. Through spatial location monitoring of 14 kinds of major tree species in 4 ha plot and community plots baseline survey, the spatial distribution and interspecific spatial correlation of spruce secondary forest arbor is studied using spatial point pattern analysis method. Then the changes of spatial distribution pattern and interspecific spatial correlation with scale. The results of the study are as follow:(1) Six thousand seven hundred and seventy-two in dividual trees were surveyed in 16005 × 5 m2 quadrats, a total of 14 species belonging to 7 families and 11 genera. The stand density of spruce forest plots is 1693/hm2. The most important 5 species of the community are Picea wilsonii Mast.Larix principis-rupprechtii Mayr, Be tula platyphylla Suk., Betula albosinensis Burkill., Quercus liaotungensis. Picea wilsonii Mast.accounted for 78.78% of the total number of community individuals, relative frequency of 23.31% and relatively significant degree of 75.09%. Species with top 7 importance values take account for 97.66% of the importance value sums. Relative abundance accounted for 96.94% of the total abundance in the plot. Basal area accounted for 98.72% of the total basal area in the plot. From the point of view of community structure, the spruce forest tree species are relatively simple in the plot. Population density difference is very large. Picea wilsonii Mast.occupies a significant advantage.(2) The average diameter of all woody plant is 14.82cm. Large trees accounted for 26.91% of the total number of community individuals. Medium trees accounted for 41.85% of the total number of community individuals. Small trees accounted for 31.24% of the total number of community individuals. Medium trees are the most,and it occupies an absolute advantage. The largest average diameter 5 species of the community are Larix principis-rupprechtii Mayr.(30.55cm), Populus davidiana (18.27cm), Picea wilsonii Mast.(14.53cm), Tilia tuan Szyszyl.(13.80cm),Pinus tabuliformis Carriere.(13.15cm). The largest diameter at breast height of individual from Larix principis-rupprechtii Mayr., and its diameter is 64.50 cm. Large individuals accounted for 86.26% of Larix principis-rupprechtii Mayr. in the plot. With the increase of scale, the number of individuals in the plot showed a trend what is from decreasing after the first increase. Forest tree diameter class distribution curve was similar to an inverted "J" type. Diameter class distribution curve of Picea wilsonii Mast. was similar to an inverted "J" type. As mentioned above, Guandi mountain spruce secondary forest has reached mature forest stage, and it updates better.(3) Total number of spruce forest plots were aggregated distribution. Five main species are Picea wilsonii Mast., Larix principis-rupprechtii Mayr., Betula platyphylla Suk., Betula albosinensis Burkill. and Quercus liaotungensis. They are all aggregated distribution. With the increase of scale, Betula platyphylla Suk., Betula albosinensis Burkill. and Quercus liaotungensis gradually reduce the degree of aggregation, finally become random distribution.The maximum aggregate intensity of them appears respectively at scale 33m,46m and 38m. Each growth stage of all main tree species is aggregated distribution. The maximum aggregate intensity of saplings appears at scale 28m. The aggregated distribution of saplings tends to decrease. Each growth stage of Picea wilsonii Mast, and Larix principis-rupprechtii Mayr. is aggregated distribution. For Betula platyphylla Suk., Betula albosinensis Burkill. and Quercus liaotungensis, which is mainly on sapling and middle-age tree, their sapling and middle-age tree is aggregated distribution and their mature tree is random distribution.(4) The correlation between Betula albosinensis Burkill. and Quercus liaotungensis as well as Betula platyphylla Suk. and Quercus liaotungensis is significantly negative correlation on scale 43m and 48-50m. The others trends from independence to positive or negative correlation with increasing scale(r> 2 m). The correlation between Picea wilsonii Mast. and Larix principis-rupprechtii Mayr. as well as Betula platyphylla Suk. and Betula albosinensis Burkill. is positive, the others are negative.(5) Since the sapling of Larix principis-rupprechtii Mayr. and mature tree of Betula platyphylla Suk. have small number and concentrate in the plots, middle-age tree and sapling of Larix principis-rupprechtii Mayr. and mature tree and middle-age tree as well as sapling of Betula platyphylla Suk. are uncorrelated. The correlation between each growth stage of other main tree species is positive with increasing scale. The correlation between Picea wilsonii Mast. and Larix principis-rupprechtii Mayr. is independent at each growth stage on small scale, and eventually become into positive correlation with the increasing scale. This indicates that mature tree of Larix principis-rupprechtii Mayr. promotes the growth of Picea wilsonii Mast. at different growth stages in plot Picea wilsonii Mast. is major species.