Studies On The Bird Communities With Reference To The Limiting Factors In The North Of North China Plain Cultivation Areas

To study the bird community diversity and the limiting factors of bird's surviving in plain cultivation areas have an important theoretical and practical meaning for resuming the bird diversity, utilizing the bird's function in integrated pest management. According to different vegetation types, we selected seventeen fixing plots in Langfang, Hebei province, used tramp count and point count methods to study the bird community structure from May to October in 2004. The forest pest investigation method was used to survey the insect community in different vegetation types. The results are as follows.1. Fifty-seven kinds of birds which are belonged to eight orders, twenty-two families were observed in summer and autumn. The species of Fringillidae, Muscicapidae, Corvidae of Passeriformes which are dominant population are respectively 8, 7, 7. The summer birds, resident birds, travel birds and winter birds are respectively 23, 21, 11, 2. The species of Palaearctic realm, widespread and Oriental realm are respectively 29, 22, 6. The relative density, distribution coefficients and important values of Tree Sparrow, House Swallow, Magpie, Hoopoe, Ashy Starling, Spot-necked Dove are higher than that of other kinds of birds. It shows that the six kinds of birds have adapted the environmental changes and became the typical species of accompanying human in the history of reclaiming the land.2. The species composition, the colony density and Shannon-Wiener indices of the middle-age forest and the younger growth, the nursery and the pure orchards are as lower as wheat fields in seventeen vegetations. These indices of old-age aspen forests and mixed woodlands are higher than that of other vegetation. It shows that the space complexity of vegetation in different woodlands have a distinct effects on the bird community.3. The bird community guilds can be divided to seven types by adopting the systematic clustering Ward method. The bird community diversity, evenness indices and probability indices of encounter of the hills in Sanhe county are higher than that of plain cultivation area which includes the Chaizhuangzi forest centre in Yongqing county and the old-age willows-aspens woodland along the Haihe river levee in Weng An county.4. The forest ages have not only a direct effect on the forest factors, such as the height and the diameter of trees, but also on the bird's surviving resources, such as foods, shelters and nesting sites. The relationships between woodlands areas and bird species and community diversity indices accord with logarithm models. The smallest woodland area in plain cultivation areas should be at least five hectares.5. The magpie have no choice of the nesting trees species and almost build their nests onthe trees whose heights are above fifteen meters and the diameters are above twenty-seven centimeters. The twenty-three percent of the magpie's nests are built on the top of telegraph poles around the farmland. These phenomens show that the tall arbors which can provide nest sites for magpies and affect their breeding success are scarce.6. Both Greater Pied Woodpecker and Grey-headed Woodpecker often nest on the tall aspens and willows. The average height and diameter of aspens are separately 15.52±3.72m and 36.65±11.62cm. The average height and diameter of willows are separately 16.97±2.34m and 27.87±9.23cm. The Greater Pied Woodpecker likes to probe insects on the trunks above six meters but the Grey-headed Woodpecker seeks insects on the trunks below five meters. The population densities, nesting rates of the two kinds of woodpeckers are higher in old-age woodlands which have many broken, withered and dead trees.7. Ninety-seven kinds of insects which are belonged to 10 orders and 48 families have been observed in different plots. Among them the percent of Lepidoptera and Coleopteras' species are separately 40%, 23%. The insect community diversities of pure aspens woods are higher than that of other vegetation types. With the increasing of aspens age, the insect species, community diversity and evenness...