我国西南地区柏木单株生物量驱动因子分析

Driving Factors for the Biomass of Individual Cupressus funebris in Southwest China

为揭示区域尺度上影响柏木地上、根和全株生物量大小的因子及其贡献情况,对我国西南地区分布的150株柏木进行地上、根及全株生物量分析,建立影响柏木单株生物量驱动因子模型。结果表明,柏木全株生物量为0.564~1099.929 kg,年龄为3~88 a。全株生物量与地上生物量、根生物量、胸径、树高、年龄、土层厚度呈极显著正相关,与年平均降雨量呈显著正相关。胸径是影响柏木地上及全株生物量的主要因子,其次是年龄、木材密度与降雨量;随机森林模型分析也证实了这一结论,此外,树高在生物量累积中也起到重要作用。研究发现,影响单株柏木生物量的生物因子和非生物因子的贡献量中,除胸径(21.09%)发挥决定性作用外,年龄(18.83%)、木材密度(8.91%)、降雨量(7.16%)也相对较高。因此,在柏木生物量模型构建中应重视这3项因子,可以提高以柏木为主的林分生物量估算精度,为其森林碳储量评估提供科学依据。

To reveal the factors that affect the biomass of aboveground,root and whole plant of Cupressus funebris and their contributions on the regional scale.The aboveground,underground,and whole tree biomass of 150 individual C.funebris plants that were collected from southwestern China were measured.The model to explore the driving factors of the biomass growth for individual plant was established.The biomass allocation of the whole tree ranged from 0.564 to 1099.929 kg and the tree age ranged from 3 to 88 a.The whole tree biomass was positively correlated with the aboveground biomass,root biomass,DBH,tree height,tree age,and soil depth as well as annual mean precipitation.The DBH was known as the main factor affecting the aboveground and whole tree biomass allocation of C.funebris,followed by tree age,wood density and precipitation.It was also confirmed by the analysis of the random forest model.In addition,tree height played an important role in biomass allocation.It was found that DBH(21.09%)played a decisive role in the contribution of biological factors and abiotic factors to the biomass of individual C.funebris,the tree age(18.83%),wood density(8.91%)and precipitation(7.16%)made relatively high contribution to the biomass of individual plant.Therefore,these three factors should be emphasized in the establishment of the biomass model in order to improve the accuracy of biomass estimation of forest and provide the scientific basis for the related carbon storage assessment.