An Ecological Study On Endangered Mechanism Of Ceratopteris Thalictroides

Ceratopteris thalictroides is an endangered plant in China and is listed as the second category of the National Key Protected Wild Plants. A total of 13 populations were found in the field investigation. According to the correlation of data and samples, habitats of some locations were investigated. The spatial pattern of 13 populations which quantity is over fifty was analyzed. The four representative habitats of communities, species association and niches were also studied, the main results are as follow:1. In recent year C. thalictroides has declined rapidly in population quantity and even disappeared from some locations in China. In our recent field investigation, we found that of the twenty-five record populations eleven have been extinct and fourteen are remain. C. thalictroides is mainly distributed in the rice field and the populations were all small and isolated. The populations were different in individual numbers and densities.2. The spatial pattern of 10 C. thalictroides populations was studied using the following measures: variance/ mean ratio, t—value, negative binomial parameter, index of dispersal, index of Cassie, index of clumping, index of mean crowding and index of patchiness. The aggregated distribution of C. thalictroides populations was indicated in the present study; however, the degrees of aggregation were different in the investigated populations. The aggregated distribution was mainly caused by the poor dispersal of spores and asexual propagators.3. Leaves of C. thalictroides in the back of which have spores were collected and taken into envelopes. The spores were preserved when released And the spore germination rate was tested. The main conclusions are as follows: the spore germination rates of C. thalictroides are between 39.30%~91.89%; the spore germination rates of C. thalictroides are different in different populations and have a great association; there are different the spore germination rate in different conditions.4. Correlation analyses indicated that the species has no significant relationships in the community. In the four communities, only Dichondra repens Forst has a great negative association with C. thalictroides; Eleocharis yokoscensis and Ludwigia prostrate have a great positive association.5. Populations of C. thalictroides occupied very narrow niches. Its population also had litter niche overlap with others, still less with domination pbpulations. The result indicated that it occupied narrow niche breadth and has litter competitive in the commonalities.The extinction of C. thalictroides populations mainly resulted from competitive commonalities and human activity. Considering the current status of C. thalictroides, both in-situ and ex-situ conservation strategies are recommended for its' conservation.