Testing a common allometric equation for predicting the above-ground weight of trees and estimation of net ecosystem production

在先前的研究（Komiyama et al. 2005 ; J.Trop.Ecol. 21：471-477）中，基于植物形态的静态模型的生物学理论，开发了用于预测红树林树种地上重量的通用异速生长方程。在本研究中，我检查这个方程是否适用于各种各样的树种生长在东亚，包括红树林。387棵树的数据，包括超过71个物种，收集了热带到温带森林位于印度尼西亚，泰国和日本。以树干木材密度为变量，这些树种的地上部分重量与树干直径之间的异速生长方程均达到显著水平。用该方程估算的地上部分重量与实测值的相对误差为19.5%，110年生次生林地上部分净初级生产量为9.96吨/公顷/年。地下NPP =0.97吨/公顷/年。因此，在110年的次生林中，净初级生产力=10.93吨/公顷/年。另一方面，净生态系统生产力（NEP）是通过从NPP中减去异养呼吸（HR）来计算的。HR假设土壤呼吸的一半，碳含量也假设树木和/或凋落物的一半。因此，在这片林分中，NEP=NPP-HR=4.98-3.71=1.27吨碳/公顷/年。

In the previous study (Komiyama et al. 2005 ; J.Trop.Ecol. 21:471-477), a common allometric equation for predicting the above-ground weight was developed for mangrove tree species based on a biological theory of statical model of plant form. In the present study, I examine whether this equation is applicable to a wide variety of tree species growing in East-Asia, including mangroves. The 387 tree data consisted of over 71 species were collected from tropical to temperate forests located in Indonesia, Thailand, and Japan. A common allometric equation between the above-ground tree weight and trunk diameter held significantly for these trees adding the wood density of trunk as a variable. The relative error between actual and estimated above-ground weight was 19.5% for this equation.In 110-year-old secondary forest, Net primary production (NPP) of aboveground=9.96 ton/ha/year. NPP of underground=0.97 ton/ha/year. Thus, in 110-year-old secondary forest, NPP=10.93 ton/ha/year. On the other hand, net ecosystem production (NEP) is calculated by subtraction of heterotrophic respiration (HR) from NPP. HR assumes half of soil respiration and carbon content also assumes half of tree and/or litter. Thus, NEP=NPP-HR=4.98-3.71=1.27 ton carbon /ha/year, in this stand.