Community Ecology Of Thuja Sutchuenensis

Based on the review of the papers about Thuja sutchuenensis and field investigations, the characteristics of T. sutchuenensis community, niche and interspecific relationships of main populations, natural regeneration and the cone characteristics and cutting propagation of the species were studied. The main results are as the following.There were 73 families of seed plants, including 150 genera and 242 species in T. sutchuenensis community. The dominant families were Betulaceae, Viburnaceae and Anacardiaceae. The rate of single-species families and the monotypic genera was high. The geographic types of the flora was various and predominant with temperate type.. The flora composition of the community reflected the significant characteristics of transition from subtropical to warm temperate zone. The types of Widespread,N. Temp.and E. Asia & N. Amer. Disjuncted mainly influenced the characteristic of T. sutchuenensis community. Phanemphytes occupied a dominant position in the community,and nanophanemphytes had the highest percentage, followed by hemicryptophyte, chamaephyte and nanophanerophyt.The dominant leaf character was papery and conaceous and the dominant leaf size was microphy. The dominant leaf margin was unentire and thedominant leaf form was simple. The dominant leaf apex was gradually apex. There were three sublayers of tree layer of T. sutchuenensis forest community. The height of the first one was above 15 m, the second was above 7 m and lower than14 m ,the third one was above 4 m and lower than 7 m. The shrub layer was lower than 4 m . The arboraceous layer was sparse.The importance value and horizontal spatial niche breadth of Thuja sutchuenensis was the biggest. The horizontal spatial niche breadths of Carpinus fargesiana, Quercus semecarpifolia and Carpinus cordata were higher than the other species, the horizontal spatial niche breadths of Daphniphyllum oldhami, Tsuga chinensis, Acer sinense and Macrocarpium chinense were lower than other species. There was a positive correlation between the horizontal spatial niche breadth and the importance value. Thuja sutchuenensis had higher horizontal spatial niche overlap with other species. This result reflected that T. sutchuenensis had strong capacity in adaptation and competition. The horizontal spatial niche overlap between the dominated species in T. sutchuenensis community was lower. This result showed that T. sutchuenensis community was stable . The vertical niche of T. sutchuenensis was lower than Quercus semecarpifolia, Acer davidii and Q. phillyraeoides because the number of mother trees and saplings were smaller. The vertical niche overlaps between Thuja sutchuenensis with Cyclobalanopsis gracillis, Cyclobalanopsis fargesii, Quercus phillyraeoides and Thuja chinensis were higher. The reason for this phenomenon was that these species had stronger interspecific competition in light factors.The overall association of the dominant tree species was negative. The pairs of positive interspecific association was as following: Quercus semecapifolia and Cyclobalanopsis fargesiana, Quercus semecapifolia andIllicium fargesii, Cyclobalanopsis jenseniana andQuercus phillyraeoides, Tsuga chinensis andSorbus wilsoniana, Cyclobalanopsis cordata var. chinensis andAcer davidi, Cyclobalanopsis cordata var. chinensis andC. jenseniana, C. jenseniana andMacrocarpium chinense, Cyclobalanopsis fargesiana andIllicium fargesii. The interspecific association of Quercus semecapifolia andAcer davidii was negative. The interspecific associations of Thuja sutchuenensis with other species were not significant. There were 26 pairs of species showed significant positive interspecific covariation and12 pairs showed negative interspecific covariation. The interspecific covariation of T. sutchuenensis with A. sinense was positive. The reason for positive interspecific covariation was these species utilizing similarresource.No significant differences were found on length, width and dry weight of cones from two natural distribution of T. sutchuenensis-Xuebaoshan and Dabashan mountains. However, the effect of different mother plants under the same condition on these characters was significant. For the cones of T. sutchuenensis, the proportion of the cones without seed was 7.1%.The average plump seed number per cone was 3. The 1 000 seed weight was lighter, only 1.112 6 g. No significant difference was found on the seed number in different cones from the same mother plant. This showed that for the same mother plant the sexual reproduction was in the same developmental level and cones development was nearly the same.Natural regeneration of T. sutchuenensis was difficult. The mode of regeneration was seed propagation. The percentage of seedling and sapling which Basal was more than 3cm was biggest in T. sutchuenensis community.The basal diameter growth and height growth of T. sutchuenensis which age was less than 15 years was regular. The best temperature of seed germination was 25℃. The seed could not germinate at 30℃. The maximum rooting and mortality rate were5 % and 48.3 % of cutting propagation in Beijing greenhouse. The maximum rooting rate and maximum mortality rate were14.4 % and 93.3 % of cutting propagation in local area. There was no significant difference between them.