Analysis of Xylem Economic Spectrum of Evergreen Broad-leaved Forest Tree Species in South Subtropical Mountain

Abstract:

The montane evergreen broad-leaved forest in the south subtropical zone has important ecological value, but the environment adaptation strategies of montane forest species are still not well understood. Based on the fixed monitoring plots of south subtropical mountain forest, xylem anatomical structure, saturated water content, mechanical strength and hydraulic structure of 25 representative evergreen tree species were determined, xylem economic spectrum was analyzed, and physiological and ecological strategies of tree species in mountain forest were clarified. The results showed that the specific conductivity of sapwood was significantly correlated with the vessel density and the proportion of vessel cavities, but there was no direct correspondence between other xylem structural characteristics and physiological functions. The lack of common structural basis led to no significant correlation between xylem hydraulic properties, saturated water content and mechanical strength. Therefore, the tree species in the mountain forest do not support the xylem economic pedigree. There was no tradeoff between sapwood specific conductivity and embolic resistance, which may be related to the lower environmental selection pressure in mountain forest. The tree species with higher community importance value had lower wood density and higher sapwood specific conductivity and saturated water content, indicating that improving xylem water transport capacity and water storage capacity was conducive to adapting to the mountain environment. This study revealed the diversity of xylem character combinations of evergreen tree species in mountain forest, which is conducive to tree species coexistence and coping with environmental changes.

Key words:Anatomical structure;Mechanical strength;Hydraulics;Wood density;Saturated water content