Study On Ecology Of Rare And Endangered Plant Handeliodendron Bodinieri Population

Handeliodendron bodinieri, belonging to Sapindaceae Handeliodendron, is a unique single-species genus and Tertiary relict plant, only occurred in subtropical evergreen and deciduous mixed forest in Karst hill in china. Because the system location of Handeliodendron bodinieri is between Sapindaceae and Hippocastanaceae, studying on Handeliodendron bodinieri have important acdemic value for relationship between Sapindaceae and Hippocastanaceae and for ancient plants, ancient geography, ancient climate. Handeliodendron bodinieri is excellent species for keeping soil and water and improving soil fertility due to its well-developed root system and large quantities of leaves. In addition to its seed riches in fragrance oil, which can been made for edible and industrial oil, and its wood can made for family furniture, agricultural tool and used for decoration. In recent years Handeliodendron bodinieri is on the verge of extinction, because of vegetation destruction and the fragility of this ecosystem in Karst hill. So far, the distribition range of natural Handeliodendron bodinieri population is narrow. The natural population is only scattered in southern Guizhou Province, including Maolan, Xiasi in Dushan, Sizhai in Pingtang, and northern Guangxi such as Huanjiang, Leye, Lingyue, Donglan, Nandan, Tian'e, Tiandong, Tianlin and so on. Vertical distribution range of Handeliodendron bodinieri is limited. In 1999 the State Council has announced Handeliodendron bodinieri as one of the first-level preservation plant species. Therefore, studying on natural Handeliodendron bodinieri population in ecology of population viewpoint and clarifying characters of Handeliodendron bodinieri population have important significance for protecting and developing Handeliodendron bodinieri population. It also can provide excelent tree species and accelerates the greening of Karst areas. In addiontion to researching on Handeliodendron bodinieri can provide scientific basis for protection and restoration of vegetation in fragile Karst zone.The characters of Handeliodendron bodinieri community, population structure, population dynamics, pattern causes, relationship between different species, competition, niche, and the interrelationship between environment was illuminated in this paper through analysis on Handeliodendron bodinieri population and its habitat. Adaption mechanisms and ecological strategies of Handeliodendron bodinieri population was clarified. The results are as follows:1. Through analysis of Handeliodendron bodinieri community, it showed that: the appearance of Handeliodendron bodinieri community is dark green, the character of leaves is mainly single-leaves, paper lesves and medium-sized leaves. Micro-phanerophytes predominate in Handeliodendron bodinieri community life-form, and Evergreen component is more than deciduous component. The community mainly occur in foot of limestone hill where water condition is better. The altitude range of Handeliodendron bodinieri community is from 550m to 650m. There is high ratio of bare rock and rare soil. Coverage of whole communities is high, and the coverage is more than 80% in arbor layer and shrub layer. The community is affluent in species composition, incuding 59 subjects, 121 genus and 127 species, and ferns have 3 subjects, 3 genus and 3 species. There are few herbs and ferns in community, and liane is not developed.2. Handeliodendron bodinieri population is small. The age structure of population is irrational. There are more big trees and small proportion in seedlings and small trees. The difference of neighbor trees'DBH and heighth is limit using differentiation indexes method. The population dynamic trend is studied adopting Chen Xiaode quantitative methods. The population have growth trend, but considering the external random disturbance the growth is very limited. However, the population will decline after a long period of time when seedlings and small trees become into adult big trees.3. The point pattern analysis was applied and the spatial characteristic was effectively described by Ripley's K(d) function in this paper. The result showed that the distribution pattern of population was mainly random on small scale from 0m to 10m, but on a large scale from 10m to 50m, population showed clumping distribution. On the large scale, although Handeliodendron bodinieri was one of dominant species, its dominant position was not obvious and the box-counting dimension is only 0.8763, reflecting low degree of spatial resource occupation. This was similar to rare and endangered plant Pteroceltis tatarinowii. The information dimension of Handeliodendron bodinieri is only 0.9799, indicating low degree of pattern intensity but large clump size. Handeliodendron bodinieri population only oppears correlation in biggish scale and the intensity of correlation was more close.4. The correlation of Handeliodendron bodinieri and other species was researched on different scale, the results showed that the correlation of Handeliodendron bodinieri and most other species was non-significant positive correlation or negative correlation, but on the biggish scale(more than 10m), the association gradually reached a significant level.5. The intraspecific and interspecific competition intensity of Handeliodendron bodinieri was different in different communities. The intraspecific competition intensity was stronger than interspecific competition in Leyi community. Handeliodendron bodinieri had small number of individuals as competitive trees, but every individual had a strong effect of competition because of its big DBH. Other species had different competition intensity as object trees because of their different population characters and niche. The trees with stronger competition intensity mainly were Cleidion bracteosum, Scheffera actinophylla and Miliusa sinensis. Whereas The interspecific competition intensity was stronger than intraspecific competition in Xiazhai 1 hektare community. The competition intensity of competitive tree against objective tree was analized by linear model, power model and inveresmodel and so on in SPSS. By comparison, the best was inverse model. The function was Y=-0.6304+3.400/X, regression coefficient was 0.8643 and the P<0.01. Therefore this model can be used for forcasting competition intensity of different size objective trees.6. The niche breadth of dominant populations was calculated using Levins index and Shaanon-Wiener index, the results showed that The niche breadth of Handeliodendron bodinieri is the biggest, and its dominance is obvious in every resource position. The number of Handeliodendron bodinieri individuals was relatively fewer. Handeliodendron bodinieri were mainly adult big trees in resouce position. It predominated in arbor layer, but there were very few seedlings and young trees in update layer below the forest.The niche overlap between Handeliodendron bodinieri and other species was calculated by Wanggang formula, the results showed that in total N, total P ,total K and value of Ph niche overlap dimensions there were general niche overlap exists between Handeliodendron bodinieri and Miliusa sinensis, Handeliodendron bodinieri and Murraya exotica, Handeliodendron bodinieri and Scheffera actinophylla , Handeliodendron bodinieri and Sinosideroxylon pedunculatum, Handeliodendron bodinieri and Cleidion bracteosum, and the values of niche overlap were high. Community gradient was a comprehensive reflection of ecological factors including total N,total P, total K ,value of Ph and so on. The niche overlaps between Handeliodendron bodinieri and Miliusa sinensis, Handeliodendron bodinieri and Scheffera actinophylla were high, indicating these species had a wide ecological amplitude and similar ecological habits. As the light factor in the vertical space, there was strong competition for Handeliodendron bodinieri, Sinosideroxylon pedunculatum, Cleidion bracteosum, Boniodendron minus popilation, so their niche overlap values were high too in community gradient.Based on the above ecological characteristics of Handeliodendron bodinieri population, the following protection measures were proposed:First, In order to expand the wild Handeliodendron bodinieri population, artificial collection of seeds and culture of seedling was necessary in nature reserve. The saplings should be planted into the suitable habitat in original distribution area when the seedlings could survive. In addition the clonal seedlings should be retained.So as to ensure clonal seedlings in the growth process to get enough light, the community coverage should be decreased.Second, the community structure should be adjusted to ensure the survival of seedlings and saplings. Selecting higher correlation and larger niche overlap species which reflected the coexistence rather than intense competition to plant with Handeliodendron bodinieri in community when recovering Handeliodendron bodinieri community. In addition chosing different Population density and spatial pattern was important to ensure population normal development.Third, before the DBH of individual reached 30 cm, the proper tending and management were necessary, which will help Handeliodendron bodinieri individuals development.In addition, to expand living space of Handeliodendron bodinieri population. Ex-situ conservation measures should be taken. Strengthening scientific research about Handeliodendron bodinieri was also important.The last, Government departments should establish regulations and raise public awareness of protection to Handeliodendron bodinieri population.