Photosynthesis-nitrogen relationship in evergreen and deciduous tree species at different altitudes on Mao’er Mountain, Guangxi Low-temperature tolerance characteristic and ecological evaluation of broad-leaved evergreen tree species Leaf longevity of main evergreen tree species of Guiyang City Nutrient resorption patterns of evergreen and deciduous tree species at different altitudes on Mao‘er Mountain, Guangxi Characteristics of Photosynthesis and Transpiration of Five Evergreen Tree Species in Summer