Tree size inequality and competition effects on nonlinear mixed effects crown width model for natural spruce-fir-broadleaf mixed forest in northeast China

Qin, Yangping; He, Xiao; Lei, Xiangdong; Feng, Linyan; Zhou, Zeyu; Lü, Jun

doi:10.1016/j.foreco.2022.120291

Cited by 17 publications

(16 citation statements)

References 73 publications

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“…The results showed that the improvement in structural diversity (CVd) in the predictive power of the CW models was outperformed by species diversity (SIM) (Figure 4), and CW was positively correlated with CVd while negatively correlated with SIM (Figure 7). Some authors considered diversity indices in the modelling process, and their conclusions are consistent with the present study (Lei et al., 2009; Qin et al., 2022; Qiu et al., 2021). Structural complexity promotes ecological niche complementarity in resource use and efficiency in the use of limited space (Lei et al., 2009), which contributes to the increase in CW.…”

Section: Discussionsupporting

confidence: 91%

“…However, as noted by Bechtold et al (2002), CW measures not only significantly increase the burden of field teams but also raise the risk of exposure to erosion and trampling of understory vegetation during large-scale forest resource surveys. Field measurements of CW surely substantially increase survey costs in mixed forests with multiple species, complicated layers and inconsistent age composition (Chen et al, 2021;Qin et al, 2022). Therefore, developing models to achieve an accurate prediction of CW in mixed forests is a proven alternative.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, developing models to achieve an accurate prediction of CW in mixed forests is a proven alternative. The allometric relationship between CW and diameter at breast height (DBH) for different regions and forest types has been extensively explored (Bragg, 2001; Chen et al., 2021; Fu et al., 2013; Qin et al., 2022; Sharma et al., 2016), but most have ignored the importance of environmental factors (e.g. climate and soil).…”

Section: Introductionmentioning

confidence: 99%

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Developing crown width model for mixed forests using soil, climate and stand factors

Tian,

He,

Jiang

et al. 2024

Journal of Ecology

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The tree crown is a useful measure of tree vigour and is highly relevant to a tree's environmental adaptability. Crown allometry depends on environmental and stand conditions. Several studies have focussed on the effects of climate change and competitive intensity on the crown, but the regulatory role of soil resources and diversity on crown allometry and carbon allocation has been neglected. Data from 20,994 trees in 232 mixed forests collected between 2011 and 2019 were located near four major mountain ranges in northeast China. The proposed crown width model includes the stand developmental stage, soil, climate, competition intensity, species mixture, species diversity, structural diversity and their interactions. We observed that the cross‐species allometric scaling exponent does not conform to the universal scaling law. Our results showed that crown width increased with increasing soil bulk density, quadratic mean diameter and coefficient of diameter variation but decreased with increasing de Martonne aridity index, basal area, Simpson index and species mixture. The interaction between quadratic mean diameter and soil bulk density had a significant negative effect on crown width. The influence of a particular factor within the interaction term on crown width was modulated by the gradients of other factors. Furthermore, soil bulk density contributed more to crown width modelling than the aridity index, and structural diversity had a greater effect on crown width than species diversity. Synthesis. Our results provide new insights into the environmental variability of crown allometry in mixed forests under global change, which is critical for improving regional and global estimates of forest biomass and carbon stocks.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Developing crown width model for mixed forests using soil, climate and stand factors

Tian,

He,

Jiang

et al. 2024

Journal of Ecology

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“…Several landmark studies have observed that crown growth is closely related to biotic factors such as tree size (Raptis et al 2018;Russell and Weiskittel 2011) and competition (Sharma et al 2016;Sharma et al 2017), as well as abiotic factors such as site conditions (Fu et al 2013) and topography (Bechtold 2004). Given the objectives of this study, two types of covariates that are convenient to calculate and apply, including tree size and competition, were tested to capture the variability of CR among stands and optimize models (Hasenauer et al 1998;Qin et al 2022). Site quality variables were not considered in this study because they are more applicable to pure even-aged forests rather than mixed-uneven aged forests (Huang and Titus 1993).…”

Section: Addition Of Covariatesmentioning

confidence: 99%

“…The negative influence of HCB and THT on the CR may be attributed to resource allocation strategies related to biomechanical and hydraulic constraints (Zhang et al 2019). The significant negative influences of competition on the crown may be since, with limited resource availability, the larger the competition, the fewer resources available to individual trees (Gill et al 2000;Hemery et al 2005;Qin et al 2022). Canopies could optimize crown filling by changing structure and growth strategies through their plasticity and vertical stratification to efficiently use aboveground space (Morin et al 2011;Pretzsch 2014), adapt to the changing environment of competing neighbors (Gao et al 2021;Kaitaniemi and Lintunen 2010;Longuetaud et al 2013), and efficiently utilize light resources (Jucker et al 2015;Pretzsch 2019).…”

Section: The Growth Trend Of the Four Crmentioning

confidence: 99%

Two new methods applied to crown width additive models: a case study for three tree species in Northeastern China

Wang

Jiang

Xin

et al. 2023

Annals of Forest Science

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Key message The non-linear seemingly unrelated regression mixed-effects model (NSURMEM) and generalized additive model (GAM) were applied for the first time in crown width (CW) additive models of larch (Larix gmelinii Rupr.), birch (Betula platyphylla Suk.), and poplar (Populus davidiana Dode). The crown radii in four directions (CR) exhibited different growth trends and responded differently to tree size and competition variables. In the absence of calibration, GAM was more accurate than NSURMEM for CR and CW predictions. Context Crown radii in four directions (CR) and crown width (CW) are fundamental indicators used to describe tree crowns. The complexity of the CR growth in four directions of different tree species in natural forests is often ignored. There is logical additivity among CR and CW that is also often overlooked. Furthermore, the existing methods applied to CW additive models have some drawbacks. Aims We aim to: (i) evaluate the utility of two new methods in developing CW additive models for larch (Larix gmelinii Rupr.), birch (Betula platyphylla Suk.), and poplar (Populus davidiana Dode) in natural secondary forests of Northeastern China; and (ii) explore the growth patterns of CR in four directions to gain important ecological insights. Methods The non-linear seemingly unrelated regression mixed-effects model (NSURMEM) and generalized additive model (GAM) were used to develop CW additive models and to explore crown growth patterns. The predictive ability of the additive models was evaluated using leave-one-plot-out cross-validation (LOOCV). Results At a fair level without calibration, GAM provided slightly better results than NSURMEM. The response of the four CR to tree size and competition variables is different and may be non-uniform due to complex stand conditions and tree growth strategies. Conclusion The newly provided methods applied to additive models are available for external datasets. GAM is recommended in the absence of calibration. This study has important implications for the understanding of natural forest dynamics and decision-making for critical stand management.

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Effects of climate and competition on crown width: a case of Korean pine plantations

et al. 2022

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Tree size inequality and competition effects on nonlinear mixed effects crown width model for natural spruce-fir-broadleaf mixed forest in northeast China

Cited by 17 publications

References 73 publications

Developing crown width model for mixed forests using soil, climate and stand factors

Developing crown width model for mixed forests using soil, climate and stand factors

Two new methods applied to crown width additive models: a case study for three tree species in Northeastern China

Effects of climate and competition on crown width: a case of Korean pine plantations

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