Study On Ecological Adaptive Mechanisms Of Seed Special Germination System Of Cyclobalanopsis Chungii

Cyclobalanopsis chungii is a kind of Fagaceae Cyclobalanopsis which is the important timber species and is also a cash plant in southern China. This paper was based on the propHase study of our studying team. Yunzhong-Mountain Natural Reserve, Minqing C. chungii forests and Jianou Houping village of Fujian were taken as research objects. The water permeability of C. chungii seeds coats during seed germination and the biotic measurement of different parts of C. chungii seed were investigated, the antioxidant enzymes, the contents of MDA and polypHenol oxidase during seed germination of C. chungii from different origins were compared, in order to reveal eco-pHysiological mechanism of C. chungii seed germination. To reveal the natural regeneration mechanism of C. chungii natural forest, the seed rain, ground seed bank and soil seed bank of C. chungii natural forest in Minqing C. chungii Forest Natural Reserve were investigated. We also analyzed the relationship between germination character and population characters from the community and population characteristics of different C. chungii forests, in order to reveal the ecological adaptation significance of it. We hope to provide theoretical foundations and technologies for protecting C. chungii and enlarging its population. The main results of the study were as follows:1. The study of water permeability of C. chungii seeds coats during seed germination shows that the water absorption of every germination stage of intact seeds increased first and then decreased, while the seeds without embryo skin were changed by wave-type. The time of intact seeds reached the highest water absorption were first increases later reduces with the prolonging of the germination time, while the time of the seeds without embryo skin reached the highest water absorption were almost all at 16ds. The water absorption of intact seeds were bigger than that of the seeds without embryo skin in every germination stage, it had turned out that seed coat is one of the factors in hindering C. chungii seeds from absorbing water.2.Seed of cabbage treated by the methanol extract from C. chungii seeds, the results showed that C. chungii seed contains some substances, which enhance seedling growth when its concentration was lower, inhibite when the concentration was higher, which were related to seed water absorption. The results can support the previous results and explain the germination characters of C. chungii seeds.3. The activities of antioxidant enzymes and MDA concentration during seed germination of C. chungii from different origins were determined, the results showed that the activities of POD and SOD of C. chungii from different origins had the same changing tendency, but change value and range had same differences. The activities of POD and SOD of C. chungii from Jianou were larger than that from Anxi and Minqing in every germination stage. The change tendencies of MDA concentration of C. chungii from three origins were contrary to the change tendencies of SOD activity, but MDA concentration and change range were different. The change tendencies of MDA concentration of C. chungii seed from Jianou were bigger than that of seed from Anxi and Minqing.4. The contents of polypHenol oxidase (IAA, GA₃, ABA and CTK) during seed germination of C. chungii from different origins were compared. The results showed that the IAA, ABA and CTK concentration of C. chungii seeds from Anxi were higher than seeds from the other two regions in every germination stage, the changing range were respectively 82.78～120.61 ng/g·FW,95.19～108.63 ng/g·FW and 13.28～16.76 ng/g·FW. Seeds from Jianou had the lowest. The GA₃ concentration of C. chungii seeds from Jianou were higher than seeds from the other two regions, the changing range was 12.03～24.38 ng/g·FW, seeds from Anxi had the lowest, its changing range was 11.41～14.44 ng/g·FW.5. The seed rain and ground seed bank of C. chungii natural forest in Minqing C. chungii Forest Natural Reserve were investigated by the located observation. The results showed that the duration of seed rain lasted two months and the peak of seed rain was during late November to early December. There was great difference among the proportions of different kinds of seed, in which the worm-eaten seed account for 42.35% and the germinating seed account for the least. The proportion of worm-eaten seed account for 54.03% in the ground seed bank, the amounts of intact seed and germinating seed decreased largely compared with that in the seed rain. However, the ground seed bank and seed rain had the similar changing tendency. The seed survive rate and the seed eaten rate by animals were respectively 42.61% and 46.04%, which showed that eaten and carried by animals were one of the main reasons for the seed loss.6. The soil seed bank of C. chungii natural forest in Minqing C. chungii Forest Natural Reserve was investigated. The results showed that there were 69 kind seeds of different species in the soil seed bank. The seed storage of subsoil was larger than that of upper layer in all sampling points. The Simpson index and Shannon index of subsoil were also larger than that of upper layer of soil in vertical distribution of all sampling points. The diversity pattern of total soil seed bank was the same as that of every sampling point. The vigor seed amount was abundant, which belong to 33 families and species. The seeds uneven distribution and most of these seeds distributed in the soil layer of 2-5 cm. The number of seeds in soil seed bank was smaller than ground vegetation. The population similarity level between soil seed bank and ground vegetation was low, the similarity coefficient was only 0.201.7. The population similarity level among Yunzhong-Mountain Natural Reserve, Minqing C. chungii forests and Jianou Houping village were calculation by Sorensen index. The results shows that the similarity coefficient between Jianou and Minqing C. chungiii community was the largest, and that between Jianou and Anxi C. chungiii community was the smallest. The population similarity level have little difference among three regions, it may have some relationship with their different climate zone.8. The species diversity of three different C. chungiii communities was compared. The results showed that the sequence of compared all diversity indexes of tree layers were Jianou > Minqing > Anxi, and the sequence of compared all diversity indexes of shrub and herb layers showed contrary result: Anxi > Minqing > Jianou. The kinds of species were turn more as the latitudinal of C. chungiii forest increased, but the species diversity of all community was turn down.9. The succession law of populations of three different C. chungiii communities was compared. The results showed that the frequency of C. chungiii at the main story of communities and it was obviously dominant. The frequency at succession layer and regeneration layer of Jianou C. chungiii communities had some differences with that of other two regions. Yunzhong-Mountain Natural Reserve and Minqing C. chungii forests had the same results, its seedling was less and regeneration was quite slower, it could also be likely to threaten development of C. chungiii forest in future..10. The C. chungiii communities of Yunzhong-Mountain Natural Reserve and Minqing C. chungii forests were divided into 5 grades. The results showed that the population age structure of different geograpHy position of C. chungiii forests were similar, all for spindle-type. This type of structure has many tree individuals at middle age, and the young or aged tree individuals are quite little. It was considered as a decline population.