Analysis Of Influence Factor Of Natural Regeneration Of Woody Plants For Betula Albo-sinensis In The Southern Slope Of Qinling Mountains

Qinling is the natural dividing line between north and south climate, the Yangtze river and Yellow River in China, it’s also the intersection of Oriental and palaearctic animals and north China, central China, southwest and the qinghai-tibet plateau various floristic composition. Special in geographical position, rich in wildlife species, high in biodiversity, Qinling has been hailed as the biological "gene pool" in China and all over the world. Betulaceae Betula albo-sinensis is main dominant species, its primary distribution area is warm temperate zone and north subtropical high and middle mountain areas, generally vertical distribution on the deciduous broad-leaved oak forest belt. Based on previous studies, it was used to study that Betula albo-sinensis Forest community structure and influencing factors(slope direction, slope, elevation, etc) of natural regeneration on the Southern Slope of the Qinling Mountains, the main results are summarized as follows:(1)Betula albo-sinensis Forest are constituted with 23 families, 32 genera, 42 species plants within Betula albo-sinensis Forest community, woody and herbaceous species are rich; In view of the dominant species of Betula albo-sinensis community, Betula albo-sinensis, the dominant specie of arborous layer has important value(47.27%); Viburnum glomeratum Maxim and Fargesla spathacea, the dominant species of shrub layer shrub layer have important value(32.73% and 29.23%); Carex hancockiana and Carex capolifomis, the dominant species of herbaceous layer have important value(38.80% and 31.67%).(2)According to Raunkiaer life system, statistical analysis of Betula albo-sinensis community composition suggests that arbors, shrubs and herbaceous plants account for 31.0%, 35.7% and 33.3% in Betula albo-sinensis forest, Phanerophytes, chamaephytes, hemicryptophytes, cryptophytes and annual plants account for 64.3%, 4.8%, 9.5%, 19.0% and 2.4% in Betula albo-sinensis biological spectrums, the species diversity indexes of tree, shrub and herb layers are not high and the community structure is relatively simple in Betula albo-sinensis forest.(3)Betula albo-sinensis forest biomes can be divided into the following two associations: Ass. Betula albo-sinensis — Viburnum glomeratum Maxim. — Carex hancockiana; Ass. Betula alto-sinensis — Fargesla spathacea — Carex capolifomis.(4)There are woody plant seedling, sapling 34 species under Betula albo-sinensis forests, including 16 tree species and 18 shrub species; Fargesia is dominant species, Rubus corchori folius is sub-dominant species, Litsea cubeba, Rosa omeiensis and Rosa prattii are third dominant species in update plants; Low in topographical factors requirement, strong in adaptability, fargesia can make full use of environmental undergrowth resources; lived in sunny slopes, stream, valley, desert and density moist places in thickets, Rubus corchori folius, the Pioneering plants are in obvious dominant position; Betula albo- sinensis, dominant plants have not obvious advantages in the update plant, at the same time, the important values of the other 14 woody species are smaller, it’s explained that the poor ability of natural regeneration under Betula albo- sinensis forest; Sprout regeneration Occupied the main advantage, seedling regeneration Occupied small proportion in trees and shrubs, it has disadvantages to the expansion of species and structure optimization of the secondary agencies; seedlings and saplings have larger density and occupied larger proportion in High level 20 to 39 cm, 40 to 59 cm, 160 cm, 180-160-199 cm and 200 cm above. The number of seedlings is relatively small in high level 0-19 cm, to some degree, restricting natural regeneration capacity of Betula albo-sinensis forest.(5)Under the same geographic condition, sunny enough in sunny slope is conducive to the growth of saplings; Less sunlight in shady slope is not conducive to the growth of saplings. It’s eneficial to the growth of saplings that the content of soil nutrient and moisture content increase with the altitude. The elevation over 2200 m, the gradually reduced temperature in the forest affected the growth of the saplings. Saplings updating density of Betula albo-sinensis forest in middle slope is maximum, the density in upper and lower slope comes second.