| Study arid protection on endangered species is a major part of the contents of biodiversity which is one of hotspots of world's studies. Alsophila spinulosa which is survival plant from the end of the Cretaceous Period and the forepart glacier of the Tertiary Period and one of the oldest living fossil in the world and the only remnant arboreal fern at present is Chinese endangered protective plant in the first class. The arboreal fern was been of great value for study on geologic climate and origin and evolution of plant and geographical flora besides it possesses horticultural ornamental and medicinal value and many other uses. So it is very significant for exploration of endangered mechanism, valid protection and exploitation and utilization of resource of Alsophila spinulosa as also protection of biodiversity etc to carry on ecological study on Alsophila spinulosa.Population ecology and ecological field characteristics of Alsophila spinulosa in different sites in Guaxi Alsophila spinulosa nature reserve in Fujian province were analyzed and discussed by quantitative statistic method in the work, including size structure, spatial distribution pattern and its fractal trait and life process of the population, as well as studies on character of ecological field and change law of field gradient of individual aboveground and ecological field property of population aboveground. The results indicated as follows:(1) By applying the method of "spatial sequence instead of temporal change". Size structures of Alsophila spinulosa populations in seven sites took on growing, stable, adult and senescent four kinds of forms with stem height as the indices of individual size.Spatial distribution patterns of Alsophila spinulosa populations in the different sites were different with the types of clump or random. Clump distribution appeared in the growing populations generally with stores of seedlings and a small quantity of adults and random distribution in the stable or senescent populations with more adults and less seedlings relatively. Possessing diffusivity, distribution pattern of Alsophila spinulosa population changed from clump to random in the course of development furthermore. Seedlings appeared as clump distribution, while large plants random. Degree of aggregation of the population patterns varied with the different sampling scales, values of dispersion index I decreasing with increment of quadrat scale by and large. Therefore, sampling scale had a certain effect on the measurement of spatial distribution pattern of Alsophila spinulosa population.(2) Alsophila spinulosa populations in 8 sites existed variant scale variation and fractal trait on spatial occupation, pattern intensity and spatial correlation of individuals. The box-counting dimension ranged from 0.3132 to 1.1189 and the order of that was Q3 > Q6 > Q7 > Ql > Q2 > Q4 > Q5 > Q8, information dimension from 0.3031 to 1.078 and the order of that Q3 > Q7 > Q6 > Ql > Q2 > Q5 > Q8 > Q4 and the correlation dimension from 0.7450 to 1.1453 and the order of mat Q3 > Q6 > Q8 > Ql > Q5 > Q7 > Q2 > Q4. The spectrum of fractal dimension showed that spatial structure characteristicses of those populations in sites Q1,Q2, Q3, Q6 and Q7 were similar, the same to those in sites Q4, Q5 and Q8.(3) Time-specific life table of Alsophila spinulosa population established based on highness class revealed that seedlings were abundant relatively and structure of the population was the type ascending in the primary stage and stable in the late stage. The survival curve belonged to the typical type of Deevey-III with the high mortality in the earliness and the survival values fluctuating not large in the late stage. In the process of development of the population, there were three death peaks of which occurrence was perhaps one of the important reason of population endangerment.Survivability of the population dropped down monotonously, and accumulative mortality rose up correspondently with increment of the age class (highness class) and varying extent was large in the earl...
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