| As one of the Rare & endangered species, Alsophlia spinulosa is national second-class protective plant, and was listed in the international endangered species protection list by IUCN. In China, its main distribution regions include SiChuan, YuNan, GuiZhou, GuangDong, GuangXi, FuJian, and so on. Due to deficiency of a thorough protection mechanism, a large number of A. spinulosa had suffered different extent destroy. Meanwhile, the ecological environment is getting worse, and the propagation & survival turned out to be more difficult, thus, the number of Alsophlia spinulosa is getting less and less. It seems so urgently to get down to research on population structure and dynamics, and discuss its current situation and trend of A. spinulosa.The study on population structure and dynamics is one of the main points and hot issues in phytoecology research area. In this paper, following the principle of genecology, and with the help of Survival analysis, ecological niche, spatial pattern and interspecific association analysis, the population structure and dynamics of A. spinulosa in RongXian JinHua Natural Preservation area was studied. The results showed that:1,Choosing stem height as a measure of age to establish the age structure, all 6 sample plots presented two types in general. Increasing type includes Q1,Q2,Q4 and recession type includes Q3,Q5,Q6. Each sample plot had a large amount of seeding, but low survival rate.2,Applying the method of space instead of time, compiling the static life table which was based on age level. The data showed the 2ed age level & the 13th level had higher mortality. It means the natural environment was not beneficial for A. spinulosa seedings'growth.3,The survival curve of Alsophlia spinulosa population had both characteristic of type Deevey—Ⅰ& Deevey—Ⅲ. The number of survival individual decreased sharply in the earlier stage with a high mortality, and tend to be gently from the 3ed age level to the 10th age level. When got into the 12th age level, the mortality rate increased, and reached the peak at the 13th age level.4,The downtrend of survival rate relative to high mortality at each age level. Meanwhile the accumulation mortality display increasing trend in general, and the rising amplitude showed stage of seeding larger than the other. And the death density display decreasing trend, the decrease amplitude showed large in the early stage, gentle in the later.5,Based on the niche value analysis, the results showed A. spinulosa occupied an important position in both tree layer and herb layer. The niche values in drop order was:Alsophila spinulosa>5(Eurya spp.)>Sloanea leptocarpa>Maesa japonica> Lithocarpus fangii. In the herb layer was:Alsophila spinulosa> 17(Pteris spp.)> Elatostema involucratum> Myrioneuron faberi> Alpinia japonica> Asplenium unilaterale>Osmunda Vachellii>Neottopteris simonsiana>Microlepia marginata> Dryopteris fuscipes.6,The niche breadth was analysised quantitatively in this article, the Levins & Hurlbert niche breadth shows the results were in agreement. In the tree layer, Alsophila spinulosa,5(Eurya spp.),Sloanea leptocarpa,Maesa japonica,Lithocarpus fangii had bigger niche breadth, their Levins & Hurlbert niche breadth are 5.9872,5.9685,5.8518,5.6517and 0.9974,0.9937,0.9704,0.9303. In the herb layer,17(Pteris spp.),Elatostema involucratum,Alsophila spinulosa,Alpinia japonica,Osmunda Vachellii had bigger niche breadth, their Levins & Hurlbert niche breadth are 5.8564,5.7740,5.5767,5.6687,5.5921 and 0.9713,0.9548,0.9153,0.9337,0.9184. So A. spinulosa was the dominant species in the community which took an important position, and high degree of resource utilization.7,Trough the niche similarity analysis, we can see Alsophila spinulosa had higher niche similarity with the species that had bigger niche breadth, nevertheless had lower niche similarity with the smaller ones. Thus, A. spinulosa's resource utilization was more similar to the ones'had bigger niche breadth, and was likely to form mixed forest.8,Alsophila spinulosa had high Niche overlap with species which had bigger niche breadth, and was close to their biotype, similar with their ability on resource utilization.9,Using 4 aggregation index to find out that 6 sample plots' spatial distribution pattern was aggregated distribution, and the intensity was:Q2>Q1>Q6> Q5>Q4>Q3. Meanwhile the Box Dimensions & Information Dimensions showed A.spinulosa population in Q2 had the highest spatial occupation capacity, its colonizing & dominant status was obvious.10,The result of Spearman Rank Correlation Analysis showed 65% of the populations presented positive association. A.spinulosa had extremely significant positive association with Aucuba himalaica,Microlepia marginata,(15),(25),(3),Selaginella delicatula,Osmunda Vachellii,(18),Saurauia tristyla. It meant A.spinulosa had the similar request of environment with these species, and got interdependent in the long-term adaptation. |
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