Studies On Biomass Of Bashania Fargesii And Fargesia Qinlingensis In Enjoying Forest Communities Of Giant Pandas In The Qinling Mountains

Bashania fargesii and Fargesia qinlingensis are principal food sources for Qinling giant pandas. In Qinling Mountains, B. fargesii distributes mainly in the broad-leaved forests or coniferous and broad-leaved mixed forests in the elevation of1100～1900m, and F. qinlingensis distributes mainly in the broad-leaved evergreen forests or coniferous and broad-leaved mixed forests in the elevation of1600-2900m. The giant pandas’survival and activity are associated with growth status, quantity and spatial pattern of B. fargesii and F. qinlingensis. The biomass of the both bamboo is crucial not only in exploring Qinling giant pandas’ habitats selection, but also in providing guidelines for the conservation actions of Qinling giant pandas. However, there is lack of empirical research on the spatial distribution characteristics of B. fargesii and F. qinlingensis biomass. This study was aimed to investigate the site effects on biomass distribution of B. fargesii and F. qinlingensis. The key factors and the suitable site condition for the bamboo growth were assessed.The bamboo biomass, height, basal diameter, population, and density with different site conditions (including elevation, slope, slope position, slope aspect, and canopy closure) were measured in106sample plots of giant pandas habitat in Foping, Huangbaiyuan, Guanyinshan and Pingheliang natural reserves. These natural reserves are located on south-facing slope in the middle of the Qinling Mountains in Shaanxi Province. In this research, the effects of different site conditions on the bamboo biomass were analyzed by using the methods of t test and multiple regression with SPSS software.Our results show that the distribution of the bamboo varied regularly by site factors as follows:(1) The bamboo biomass varied significantly in different investigated areas. In this study, the rich biomass density and favorable growth status of B. fargesii were found in Foping and Huangbaiyuan natural reserves, and the similar status of F. qinlingensis were found in Foping and Guanyinshan natural reserves, while the poor biomass density and less favorable growth status of the both bamboos in Pingheliang natural reserves. This was probably caused by the different hydrothermal conditions and characteristics of the community structure of the different investigated areas.(2) There was a remarkable correlation between the bamboo biomass and vegetation type. When canopy closure of the over wood was over0.6, B. fargesii and F. qinlingensis grew feeble. B. fargesii grew better in Quercus aliena var. acuteserrata forest, and its biomass order in Quercus aliena var. acuteserrata forest with different ages was sapling plantation> mature plantation> composite plantation. F. qinlingensis grew better in birch forest, and its biomass increased with the age of mature Abies fargesii.(3) The bamboo biomass changed with elevation. The good B. fargesii communities were located in mid or lower and gentle slope between the elevation of1500m and1700m. The good communities of F. qinlingensis formed in gentle slope between the elevation of2400m and2700m. Both of the bamboos grew better on the sunny slope.(4) The stem biomass of the both bamboos was the largest, and accounted for nearly half the total biomass. The proportion of underground biomass of F. qinlingensis was obviously higher than B. fargesii, so was the rhizome, fine root and stem.(5) There were certain differences of bamboos biomass in different communities where the giant pandas enjoyed living. The difference of bamboos total biomass was not significant between the summer and winter habitats, while the total biomass was poor in transition zone of the giant pandas. However, the biomass of B. fargesii distributed in leaves was higher than it of F. qinlingensis.In conclusion, the dominant site factors influencing B. fargesii biomass were slop position and canopy closure. However, different site affected on F. qinlingensis biomass was more significant. These areas where the biomasses of both bamboos were large seem to be the most suitable habitats for the giant pandas.