| Based on the idea that Giant Panda, forests and bamboo mutually effect each other and co-evolution, the indicator system for diagnosing giant panda habitat health is established. Then the forest structure and dynamics and the relationship between forest structure and disturbance are studied. At last the models and rules for restoring degraded giant panda habitat are purposed. The indicator system for describing the degradation of giant panda′s habitat is developed, including three kinds of indicators as topography , forest community and feeding bamboo. The topographic indicators include altitude, slope, aspect etc.. Height of trees and shrubs, density of trees and shrubs, shrub species, shrub coverage, tree composition and canopy are employed to evaluate the forest community. The quality of the feeding bamboo is assessed by the density and height of bamboo, bamboo trunks base diameter and the percentage of young bamboo. In brief, the standards for the restoration of the habitat of giant panda are as following: altitude between 2 600~3 000 m, slope between 25~45°, tree height<15 m, shrub height<2 m, shrub density >5 000 individuals/hm2, tree density<300 individuals/hm2, shrub species> 5 species, percentage of Abies and Picea in forest composition>50%, shrub coverage between 80%~100%, canopy<50%, bamboo density between 35~102 individuals/m2, bamboo base diameter>4.4mm, percentage of young bamboos in all bamboos>25%, bamboo height between 1.8~2.8 m。In the end, restoration, reallocation and rehabilitation as three approaches are supposed for the restoration of giant panda′s habitats. It is important to restore degraded forests and bamboo and disturbed evolutionary relationship among giant panda, forests and bamboo, which are disturbed by gap regime such as gap size, age, frequency, turnover time and response of trees to gap size and age. The mechanism of gap disturbance should be explored for restoring degraded giant panda habitat. Disturbance regime of 62 gaps of subalpine forests in Wang Lang Natural Reserve is analyzed. Abies faxoniana and Picea purpurea are the main gap makers in the process of gap making. Among the makers, the ratio of numbers of Abies faxoniana is 79.62%. And the ratio of the numbers of Abies faxoniana with radial of 20-30 cm to all gap makers was 27.42%. As to Picea purpurea, the ratio of numbers with radial of 20-30 cm is 18.75% in all gap makers by Picea purpurea. The ratio between the numbers with radial less than 20 cm or 40-60 cm and all the Picea purpurea makers is about 6%. The turnover time of gap disturbance is 469a. The average length of the long axis of the expanded gaps is 20.7 m, the short one is 13.7 m. The ratio of length between the long axis and the short axis is 1.539. Average area of expanded gap is 230.088 m2,ranging from 100 m2 to 300 m2。The ratio of numbers of gaps that formed from 50 years ago to 60 years ago is 30.65%,and there is almost no gaps with age of more than 100 years. The average age of gaps is 42 years。The regeneration stage of gaps is mainly in their primary stage,the ratio is 51.61%。Uprooting is the main gap formation way, its ratio is 24.19%。Regeneration patterns and disturbance history of 6 subalpine forests are analyzed through the analysis of population structure (size, age, spatial patterns) and radial growth patterns in Giant Panda habitat in Wang Lang Natural Reserve. There is a close correspondence between forest composition, structure and disturbance history of forest stands. One of most important disturbances is the canopy disturbance that led to the formation of gap as the result of uprooting treefall, standing death, and trunk snapping. Gap formation in these stands is a relatively continuous small-scale process during the past period of 200 years. Treefalls and trunk snapping cause growth releases on average 6 year. Gap formation initiate the tree regeneration and maintained current forest canopy composition. At the same time, tree seedling competition with bamboos and bamboo growth cycle controlle patterns of tree regeneration and therefore community structure and dynamics. The compound system composed of giant panda habitats and human communities effect and disturb giant panda habitat suitability. Three models such as emigrating, developing and comprehensive are proposed for rationing community economy in order to restore degraded giant panda habitat. Restoration and rehabilitation through natural succession are recommended for restoring degraded habitat. And man-made ecosystem is not reasonable approach for giant panda habitat restoration. At the same time, the approach and rules for restoring main kinds of degraded habitat are purposed. |
