Study On Ecological Function Of Rare And Endangered Rhinopithecus Bieti In Cold-temperature Forest

The study on the ecological function of species has become a hot topic with the loss of global biodiversity.At present,the studies on the ecological function of rare mammals remain scarce,while rare mammals are often the key species with unique ecological functions in the ecosystem.Understanding the ecological function of rare mammals is helpful to deepen the understanding of the ecological function of rare species,as well as to the effective conservation and management of rare animals and their habitat.The Black-and-white snub-nosed monkeys(Rhinopithecus bieti)is a first-class national protected animal,and is listed as endangered in the IUCN Red List.R.bieti is the flagship species in the cold temperate forest ecosystem.Studies about ecological function are not only helpful to expand the knowledge of R.bieti,but also to provide insight of the functional ecology of rare animals.It can also provide key basic data for the effective conservation of R.bieti and its habitat and the scientific planning of the reserve.Therefore,it has important academic value in the study of functional ecology of rare animals and has important guiding significance in the protection of R.bieti.R.bieti is a large arboreal primate,the canopy structure may be affected by the broken branches of monkeys in the forest canopy.Growth of Usnea longissimi can lead to the death of trees,and feeding from R.bieti on U.longissimi may be beneficial to forest health.The effect of monkeys on the canopy structure and the strategy of feeding on U.longissimi may promote the growth on U.longissimi and contribute to the self-maintenance of food resources.The effect of monkeys on canopy structure may also increase plant diversity and play an important role in maintaining the stability of forest ecosystem.First,a systematic and comprehensive survey was carried out in the southern unit of R.bieti.Then,in order to explore the direct effect of monkeys on the canopy structure,I carried out behavioral ecological monitoring,and compared crown and canopy openness between the area with year-round activity now and the areas where the monkeys had disappeared for different years.Thirdly,through the artificial control experiment,comparing the changes of branches in different health conditions and whether covered by U.longissimi,I explored whether the U.longissimi was harmful to the trees,and through artificial simulation R.bieti to enlarge canopy openness and feed on U.longissimi,I explored the effects of canopy structure changes and monkey feeding on the growth of U.longissimi.Finally,this study explored the indirect effects of R.bieti on plant diversity and forest community succession by comparing the differences of composition structure,horizontal structure,vertical structure,plant diversity and age structure of community between the area with year-round activity now and the areas where the monkeys had disappeared for different years.The following important conclusions have been obtained:1.Excessive growth of U.longissimi might harm the health of trees based on human control experiments,while monkeys feeding on U.longissimi is good for forest health.R.bieti preferred the partial feeding pattern on U.longissimi in this study,and combined with the artificial simulation experiment,we found that partial feeding pattern of R.bieti will promote the growth of U.longissimi.Therefore,R.bieti play the role of“Doctors” in forest health maintenance and “farmers” in own food supply.2.For the first time,we revealed that broken branches were mainly caused by feeding and moving based on the behavioral ecological monitoring of R.bieti and the comparison of crown and canopy openness in different areas.The results showed that the broken branch behavior of R.bieti shortens the crown and enlarges the canopy openness,and plays a role in canopy pruning and reshaping.Therefore,R.bieti can be considered as the “Engineers” in the cold temperate forest ecosystem.Simultaneously,the increase of canopy openness also promoted the growth rate of U.longissimi.3.By comparing the forest community structure in the area with year-round activity now and the areas where the monkeys had disappeared for different years.I found that the composition of species in different areas are basically the same.The vertical structure and horizontal structure of the community have large differences,and the density and height of shrubs and herbs are closely related to the canopy openness.About 20 years after the monkeys disappeared,the change of vertical structure and horizontal structure of community tends to be stable.The results show that R.bieti can shape the horizontal and vertical structure of the cold temperate forest community,and the time scale of the influence is about 20 years.By comparing the age structure of plant community,number of seedlings and proportion of cavity trees in different areas.I found that the age structure of the community in the area with year-round activity now is rapid growth type,and gradually tends to be negative with the disappearance time of monkeys.The number of seedlings and the proportion without their seed trees nearby in the year-round activity area of R.bieti were higher than those in the historical activity areas,and decreased gradually with the disappearance time of monkeys.The number of cavity trees in the year-round activity area of R.bieti was lower than that in the historical activity areas,and increased with the disappearance time of monkeys.The continuous disturbance of its broken branch behavior to the forest community makes the whole plant community in the growing stage,continuously accumulate materials and abilities,increasing biodiversity and increasing ecological elasticity.4.By comparing the plant diversity in the area with year-round activity now and the areas where the monkeys had disappeared for different years.I found that the plant diversity in the year-round activity area of R.bieti is higher than those in the historical activity areas,and decreased with the disappearance time of the monkey and it tended to be stable after the monkeys disappear for about 30 years.There is also a positive relationship between the plant diversity and the canopy openness.The results show that R.bieti plays a very important role in the cold temperate forest community,their influence on the canopy structure will promote the biodiversity and enhance the robustness and stability of the ecosystem.5.During the investigation,two new group,Heishan group and Tianchi group were found.This discovery increased the number of wild groups of R.bieti,from 15 to 17,and expanded the distribution area nearly 40 km to the south.This study is the first to explore the ecological role of R.bieti in the forest ecosystem.It showed that R.bieti can be considered as the “engineer” in cold temperate forest ecosystem.It suggests that R.bieti has a short-term direct effect on canopy structure,and also has a long-term indirect effect on forest health maintenance,biodiversity promotion,forest community succession direction regulation and ecosystem stability improvement.This study is innovative in exploring the interaction mechanism between R.bieti and forest community,and provides a new way for the study and protection of rare species in three parallel rivers of Yunnan.