Study On Population Dynamics Of Endangered Plant Abies Chensiensis

Abies chensiensis, an endangered plant, is a typical endemic species to China listed in China Plant Red Data Book. A. chensiensis is only scattered as small fragments at Mt. Qingling, Bashan and Shenlongjia from 1500m to 2300m altitude. A. chensiensis has an important effect on water source self-restraint, zoology balance etc. In order to probing into the ecological characteristic and endangered mechanism of this population, we selected the caiziping zone of Mt. Qingling where the population is the most concentrating as research zone. We made 18 plots to systematically study the geographical distribution, the bio-ecological characteristic, its population spatial distribution pattern and dynamics, population dynamics and procreation and ecology characteristic. We analyzed the reason of endangering and put forward the protection countermeasure. Firstly, the distribution zone of A. chensiensis is very narrowness. The community structure is mainly temperate zone. The communities in Mt.Qinling could be divided into 5 associations by cluster analysis of the importance values of the dominant species. The growth of its young seedlings was slower. The output of seed is not high. The community update is very difficult. A. chensiensis likes the warm and wetness climate. The individual growth is slower. The self-update capacity of community is not well. Secondly, A. chensiensis population performed clustering distribution pattern in different habitat or the different age stages. The areas for the highest congregation were in the areas with 25 m~2, 150 m~2 and 300 m~2, which could be the most proper area for population to regenerate in natural conditions. The distribution patterns on different altitudes and slope aspects were different. From low to high altitude, the clustering intensity went down. The scale for the highest clustering intensity was smaller in altitude 1500~1700 m area and it was larger in altitude1700~2100 m area. The clustering intensity in shade slope was higher than that in the sunny slope. With the population age increasing, the distribution pattern had the trend from clustering to random, and the clustering intensity performs the decreasing tendency. The area for highest congregation occurred in 50 m2 when the populations were young or middle age stages and 300 m2 when they were in old age stages. Thirdly, the analysis on the age structures of Abies chensiensis populations showed that the young individuals were seriously in short and the number of middle and old individuals was relatively rich. The analysis on the life tables and the survival curves showed that the survival curves of Abies chensiensispopulations belonged to the Deevey III, and death peaks of different populations were in period of 60-100 years old. The number differences among populations reflected the population habitat. Time sequence prediction models for different populations indicate the numbers of old individuals would be increased in the beginning and decreased finally in 20,40,80years lately. It was difficult to maintain the population stability. Fourthly, the percentage of empty seeds reached 31%. The TTC results showed that the vital seed percentage reached 45%, implying the higher ratio of seed abortion. The water content in the seed averaged about 5.7%, and the natura11y fallen seed was only 6.12% germinated. In 10 ecological factors, the tree coverage, soil organism, air humanity influenced germination of seeds positively, and human disturbance and sunlight influenced germination of seeds negatively. That the seeds were demolished by animals like squirre1, mouse and birds was higher than 94.22%. Under the same storage conditions, seeding environments showed great effects on the germination ratio, and loosen, aerated or baked soil also promoted the germination of seeds, with the germinated ratio of above 54%. Fifthly, In the future, the in site conservation should be taken as the most important management for the forest, and the natural regeneration should be promoted. At the same time, the artificial population should be expanded. We should build small forest window and promote the young Abies chensiensis growth. We should promote the adult individual burliness and enhance the seed burgeon ratio in nature condition.