典型树种胸径-边材面积异速生长关系及其影响因素OACHSSCD

The sapwood of trees plays a vital role in water transport,and its area serves as an important parameter for quantifying transpiration.However,the sampling difficulties and methodological limitations make the direct determination of sapwood area extremely challenging.Consequently,current studies predominantly estimated sapwood area based on the allometric relationship between diameter at breast height(DBH)and sapwood area.Although such allometric relationships have been established for multiple tree species,their variations and driving factors,both across different species and within species across different regions,remain poorly investigated.To fill this gap,this study systematically compiled a national-scale database of DBH-sapwood area allometric equations for China,which consists of 139 records from 59 tree species and 81 monitoring sites.This study further compared sapwood areas and their influencing factors among different species,after controlling for six DBH size classes,aiming to clarify the variations in allometric relationships among species and across sites.The results showed that the sapwood area varied significantly among species,with higher values in non-porous and diffuse-porous woods than ring-porous woods,as well as larger values of evergreen species than of deciduous species,and of conifers than of broadleaved species.Among the environmental factors,elevation showed a significant negative effect on sapwood area,but this relationship was no longer significant for trees with the DBH larger than 26 cm.Species with non-porous,evergreen,and needle-leaf functional type had higher sapwood area,especially when the DBH was larger than 26 cm.Species identity together with environmental factors explained 72.7％—82.4％of the variation in the DBH-sapwood area allometric relationship.This study established a comprehensive database of DBH-sapwood area allometric equations for different species in China,which can provide parameters for estimating transpiration of an individual tree,a stand,and the regional level.