ABSTRACT

Stem surface area (S) plays an important role in the eco-physiological processes of trees or forests such as stem respiration, self-thinning mortality, and rainfall interception. As the direct measurement of S is time-consuming and labor-intensive, models for predicting S from commonly measured tree attributes have been developed for coniferous trees grown in plantations. However, there have been no models for trees grown in natural forests. In this study, we compared regression models for estimating S using 122 sample trees of eight coniferous species felled in old-growth natural forests in Kiso district, Nagano prefecture, central Japan. The relationship of S to the product of diameter at breast height and tree height (DH) could be expressed as S = 1.924DH (R ² = 0.996), independent of the species. The estimated slope coefficient of the regression of the natural forests was close to that of plantations reported in a previous study. These findings indicated the generality and wide applicability of the model. By contrast, the estimated slope coefficient of the regression between S and basal area (G) varied with the species, and the slope was gentler in the natural forests than the plantations. Monte Carlo simulation revealed that only 20 sample trees were necessary to estimate regression coefficient for the relationship between S and DH, whereas more than 60 trees were needed if G was used as predictor. In conclusion, the regression model between S and DH is useful when predicting S of various coniferous trees grown in both natural forests and plantations.

摘要

茎表面积（S）在树木或森林的生态生理过程中起着重要作用，例如茎呼吸，自我稀疏性死亡和降雨截留。由于直接测量S既费时又费力，因此已经为人工林中种植的针叶树开发了根据常用的树木属性预测S的模型。但是，还没有用于天然林中生长的树木的模型。在这项研究中，我们比较了日本中部长野县木曾区的八种针叶树种的122棵砍伐过的天然林中砍伐的树木的S估算回归模型。S的关系胸高和树高的直径乘积（DH）可以表示为S = 1.924 DH（R ²  = 0.996），与物种无关。天然林退化的估计坡度系数与先前研究中报道的人工林相近。这些发现表明了该模型的普遍性和广泛的适用性。相比之下，S和基底面积之间的回归估计坡度系数（G）因物种而异，天然林的坡度比人工林平缓。蒙特卡洛模拟显示，估计S和DH之间的关系的回归系数仅需20个样本树，而如果使用G作为预测因子，则需要60多个树。总之，在预测天然林和人工林中生长的各种针叶树的S时，S和DH之间的回归模型很有用。