Study On The Effects Of The David's Deer Disturbance On The Habitat And Population Dynamic

In this thesis, based on the investigation of plant community in Dafeng national David's deer nature reserve in Jiangsu province,their biomass characteristics and their contribution rates,the effects of pasture disturbance on species diversity , the plant nourishment composition, soil properties, the population dynamics and carrying capacity of David's deer were studied.The relationship between the David's deer disturbance or grazing and the vegetation structure characters of their habitat,as well as soil properties were revealed. In David's deer's habitats, with the continuous increase of the density of David's deer, the structure variation mechanism of plant community was investigated, which was significant for the vegetation restoration and the ecosystem management of the Natural Reserve. The main results were described as follows: ①The plant biomass varied with the different seasons. There were more biomass in both July and September than in May,and remarkable difference between vegetations. Pennisetum alopecuroides(l.) Spreng had the greatest biomass in all plant species in the Natural Reserve, occupied 61.15 % in May, 85.57% in July and 81.02% in September. Due to the selected grazing of David's deer in different plant communities , plants with weaker disturbances had more biomass. Besides,this thesis analyzed the choice of David's deer grazing and contribution rate of different plant communities to them. ②Due to the disturbance of David's deer,the grasses that David's deer prefer to eating varied with category and biomass. Pennisetum alopecuroides(l.) Spreng play an important role,which greatly influenced the biomass that David's deer favor and enable to eat.Under the disturbance of David's deer,community components changed and both the biodiversity and the landscape heterogeneity declined. ③The nourishment components of different vegetation varied with plant species and seasons in David's deer's habitat. In the Natural Reserve Area, Gramineae and Compositae took up the foremost place. The vegetation of Compositae contained more protein than Gramineae. The protein content of Gramineae changed significantly in seasons and the period that David's deer perfer to eat was short.So overaboundant Gramineae vegetation was harmful to David's deer habitat. ④Due to the choice of David's deer vegetation types,the half-wildness David's deer affected the soil properties of their habitat.As a result,the vegetations which David's deer favorite were frequently disturbed and notably trampled.The different vegetation types also influenced the soil property,changed the content of soil water and the soil bulk density.The soil properties of the habitat is responded to the gradient disturbance of David's deer to vegetations. ⑤The dynamics of David's deer population was also belonging to the density-independent population growth. The carrying capacity of David's deer was estimated.