In this follow-on study on aboveground biomass of shrubs and short-stature trees, we provide plant component aboveground biomass (herein ‘AGB’) as well as plant component AGB allometric models for five common boreal shrub and four common boreal short-stature tree genera/species. The analyzed plant components consist of stem, branch, and leaf organs. We found similar ratios of component biomass to total AGB for stems, branches, and leaves amongst shrubs and deciduous tree genera/species across the southern Northwest Territories, while the evergreen Picea genus differed in the biomass allocation to aboveground plant organs compared to the deciduous genera/species. Shrub component AGB allometric models were derived using the three-dimensional variable volume as predictor, determined as the sum of line-intercept cover, upper foliage width, and maximum height above ground. Tree component AGB was modeled using the cross-sectional area of the stem diameter as predictor variable, measured at 0.30 m along the stem length. For shrub component AGB, we achieved better model fits for stem biomass (60.33 g ≤ RMSE ≤ 163.59 g; 0.651 ≤ R² ≤ 0.885) compared to leaf biomass (12.62 g ≤ RMSE ≤ 35.04 g; 0.380 ≤ R² ≤ 0.735), as has been reported by others. For short-stature trees, leaf biomass predictions resulted in similar model fits (18.21 g ≤ RMSE ≤ 70.0 g; 0.702 ≤ R² ≤ 0.882) compared to branch biomass (6.88 g ≤ RMSE ≤ 45.08 g; 0.736 ≤ R² ≤ 0.923) and only slightly better model fits for stem biomass (30.87 g ≤ RMSE ≤ 11.72 g; 0.887 ≤ R² ≤ 0.960), which suggests that leaf AGB of short-stature trees (<4.5 m) can be more accurately predicted using cross-sectional area as opposed to diameter at breast height for tall-stature trees. Our multi-species shrub and short-stature tree allometric models showed promising results for predicting plant component AGB, which can be utilized for remote sensing applications where plant functional types cannot always be distinguished. This study provides critical information on plant AGB allocation as well as component AGB modeling, required for understanding boreal AGB and aboveground carbon pools within the dynamic and rapidly changing Taiga Plains and Taiga Shield ecozones. In addition, the structural information and component AGB equations are important for integrating shrubs and short-stature tree AGB into carbon accounting strategies in order to improve our understanding of the rapidly changing boreal ecosystem function.

中文翻译：

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加拿大西北部北方灌木和矮身乔木的地上生物量分配

在对灌木和矮树的地上生物量的后续研究中，我们提供了植物成分的地上生物量（以下简称“ AGB”）以及五种常见的北灌木和四类常见的矮树的植物成分AGB异位模型。属/种 分析的植物成分包括茎，枝和叶器官。我们发现西北地区南部的灌木和落叶乔木属/树种的茎，枝和叶的组分生物量与总AGB的比率相似，而常绿的云杉科与落叶类/种相比，植物属对地上植物器官的生物量分配有所不同。使用三维可变体积作为预测变量，得出灌木成分AGB立体模型，确定为线截面积，上叶宽度和地上最大高度的总和。使用茎直径的横截面积作为预测变量对树组件AGB建模，该直径沿茎长度在0.30 m处测量。对于灌木部件AGB，我们实现了更好的模型拟合为干生物量（60.33克≤RMSE≤163.59克; 0.651≤[R ² ≤0.885）相比叶生物量（12.62克≤RMSE≤35.04克; 0.380≤[R ²≤0.735），正如其他人所报道的那样。对于短身材树木，叶生物量的预测导致类似的模型拟合（18.21克≤RMSE≤70.0克; 0.702≤[R ² ≤0.882）相比，分支的生物量（6.88克≤RMSE≤45.08克; 0.736≤[R ² ≤0.923）并且仅略好于茎生物量的模型拟合（30.87 g≤RMSE≤11.72 g; 0.887≤R ²≤0.960），这表明使用断面面积（而不是高矮树的胸高直径）可以更准确地预测矮树（<4.5 m）的叶子AGB。我们的多物种灌木和矮身材树异速生长模型显示出可预测植物成分AGB的有希望的结果，可用于无法始终区分植物功能类型的遥感应用。这项研究提供了有关植物AGB分配以及组分AGB建模的重要信息，这些信息对于了解动态且快速变化的Taiga平原和Taiga Shield生态区中的北方AGB和地上碳库是必需的。此外，