Relationships of Stable Carbon Isotope of Abies faxoniana Tree-Rings to Climate in the Sub-Alpine Forest in Western Sichuan Relationships of stable carbon isotope of Abies faxoniana tree-rings to climate in sub-alpine forest in Western Sichuan Responses of the Tree-Ring of Abies faxoniana and Tsuga chinensis to Climate Factors in Sub-Alpine in Western Sichuan The Influence Factors of Sub-Alpine Forest Restoration in Miyaluo, West Sichuan Spatial pattern of sub-alpine forest restoration in west Sichuan