Abstract
BackgroundLarch (Larix Mill.) forests are widely distributed in the upper parts of mountainous areas in China, playing vital roles in constructing mountain landscapes and maintaining mountain environments. Despite their importance, our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are unclear. In this paper, we investigated 155 plots from 11 natural larch forest types across the country to explore the biogeographic patterns of the structure characteristics and the allometric relationships between different structure variables for Chinese larch forests.ResultsThe structure characteristics were significantly different among larch forest types. For different larch forest types, the power function fits the relationships between tree height and diameter at breast height (DBH), average DBH and stem density, and taper and stem density well, but with different exponents among larch forest types. The power exponents of the allometric relationships between tree height and DBH for different larch forest types varied from 0.61 to 0.93 (mean = 0.86) by standard major axis regression (SMA), and from 0.51 to 0.78 (mean = 0.56) by ordinary least square regression (OLS). The 50%, 75% and 95% quantile regression (QR) and OLS indicated that the average DBH and taper of the L. gmelinii forests, L. gmelinii var. principis-rupprechtii forests, and L. sibirica forests were significantly correlated with stem density.ConclusionsThe relationship between tree height and DBH showed a power function relationship for all larch forest types in China, but with different exponents. Overall, stem density was negatively correlated with average DBH and taper. The Sect. Larix forests exhibited stand density effect. Our findings provide an important basis for recognizing the biogeographic patterns of structure factors and for the management of larch forests in China.
Highlights
Larch (Larix Mill.) forests are widely distributed in the upper parts of mountainous areas in China, playing vital roles in constructing mountain landscapes and maintaining mountain environments
Local and regional studies have illustrated that different structure variables, such as stem density, tree height, diameter at breast height (DBH), taper, and slenderness, were strongly correlated with each other, mostly showing allometric relationships, such as those between tree height and DBH, stem density
The − 3/2 self-thinning rule is the most acknowledged theory, which proposed a − 3/2 power function relationship between the mean biomass and stem density based on the geometric similarity theory (i.e., Ba ∝N−3/2, where Ba is average biomass) (Yoda et al 1963)
Summary
Larch (Larix Mill.) forests are widely distributed in the upper parts of mountainous areas in China, playing vital roles in constructing mountain landscapes and maintaining mountain environments. Despite their importance, our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are unclear. As proposed by the metabolic scaling theory, the exponent between stem density and plant size was − 2, and that between biomass and stem density was − 4/3, respectively (i.e., N ∝ Da−2, and Ba ∝N−4/3) (West et al 1997, 1999; Enquist et al 1998). Little is known about the influence of stem density on the taper (Sharma and Zhang 2004; Sharma and Parton 2009)
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