我国亚热带次生林乔木地上生物量估算的适宜样地面积初探

我国亚热带森林生物量估算研究常基于400~900 m²的小面积样地,但到底多大面积样地才较为适宜却鲜有探究。该文以浙江九龙山国家级自然保护区内三个1 hm²样地亚热带次生林为研究对象,利用生物量回归方程估算木本植物(胸径≥1 cm)的地上生物量,分析地上生物量的空间分布格局,并利用移动窗口法探讨三个次生林地上生物量估算的适宜样地面积。结果表明:(1)三个次生林木本植物的地上生物量分别为63.75 Mg·hm^-2(大岩前)、84.70 Mg·hm^-2(八通岭)和128.20 Mg·hm^-2(屁股窟),地上生物量集中分配在个体数量较少的大径级个体;屁股窟次生林的地上生物量空间变异程度高于大岩前和八通岭次生林。(2)利用移动窗口法确定的三个次生林木本植物地上生物量估算的适宜样地面积分别为2025 m²(大岩前)、2500 m²(八通岭)和3600 m²(屁股窟),森林地上生物量越高且空间变异程度越高,所需调查的样地面积越大。该研究结果可为我国亚热带森林地上生物量估算的样地面积设置提供证据,并为该区域森林生物量与碳储量的估算提供基础数据。

Appropriate plot areas of secondary forests in subtropical China based on tree aboveground biomass data

Biomass estimation studies of subtropical forests in China are often based on small plots ranging from 400 to 900 m².However,what is the appropriate sample area remains unknown.In the present study,aboveground biomass(AGB)and its spatial distribution pattern of woody plants with diameter at breast height(DBH)≥1 cm in three subtropical secondary forests in Jiulong Mountain National Nature Reserve,Zhejiang Province,East China were analyzed,and the appropriate sample areas for the AGB survey of the three secondary forests were explored by moving window method.The results were as follows:(1)The AGB of woody plants in the three secondary forests were 63.75(Dayanqian site),84.70(Batongling site)and 128.20(Piguku site)Mg·hm-2,respectively.AGB was concentrated in plants with large DBH but with a small individual number.The spatial variation degree of secondary forest AGB at the Piguku site was higher than those at the Dayanqian and Batongling sites.(2)The appropriate sample areas of the three secondary forests based on AGB data were 2025(Dayanqian site),2500(Batongling site)and 3600(Piguku site)m²,respectively.The higher the forest AGB and its spatial variation degree were,the larger sample area was required.The present study provides evidence for sample area setting of AGB survey in subtropical forests,and provides basic data for regional forest biomass and carbon storage estimations.