The stem height–diameter allometric relationship is fundamental in determining forest and ecosystem structures as well as in estimating tree volume, biomass, and carbon stocks. Understanding the effects of silvicultural practices on tree height–diameter allometry is necessary for sustainable forest management, though the impact of measures such as thinning on the allometric relationship remain understudied. In the present study, the effects of thinning on tree height–diameter allometry were evaluated using Masson pine height and diameter growth data from a plantation experiment that included unthinned and thinned treatments with different intensities. To determine whether thinning altered the height–diameter allometry rhythm, the optimal height–diameter model was identified and dummy variable methods were used to investigate the differences among model parameters for different thinning treatments. Periodic (annual) allometric coefficients were calculated based on height and diameter increment data and were modeled using the generalized additive mixed model (GAMM) to further illustrate the response of tree height–diameter allometry to different thinning treatments over time. Significant differences were detected among the parameters of the optimal height–diameter model (power function) for different thinning treatments, which indicated that the pattern of the height–diameter allometry relationship of Masson pine was indeed altered by thinning treatments. Results also indicated a nonlinear trend in the allometric relationship through time which was significantly affected by thinning. The height–diameter allometric coefficient exhibited a unimodal convex bell curve with time in unthinned plots, and thinning significantly interfered with the original trend of the height–diameter allometric coefficient. Thinning caused trees to increase diameter growth at the expense of height growth, resulting in a decrease of the ratio of tree height to diameter, and this trend was more obvious as the thinning intensity increased.

There is growing concern that public benefits from forests are underprovided in current forest management regimes and need to be increased through policy and economic measures that promote conservation. Ecological compensation is a type of institutional arrangement for the sustainable use of ecosystem services achieved by adjusting the distribution of costs and benefits among different stakeholders using economic measures. However, how to accurately and reasonably determine the compensation standard for ecological services has not been guided by scientific methods and theories. This study provides an estimation of the compensation standard for forest ecological services based on the forest multifunction evaluation and financial net present value analysis, and a case study was performed in Southwest China. The results showed that most forest types brought some economic loss to the managers but contributed great ecological benefits to the public when they were managed as ecological forests. It is crucial to incentivize forest managers to participate in voluntary conservation programs through ecological compensation. The results of this analysis can potentially guide sustainable forest management by both accurate quantification of the value of forest ecosystem services and an improved understanding of the costs of voluntary forest conservation schemes currently in use in many countries.

How trees allocate their biomass among different components has important implications for their survival and growth and ecosystem carbon cycling. Data on the distribution pattern and dynamics of tree biomass are essential for fully exploiting forest carbon sequestration potential and achieving the goal of carbon neutralization. However, there has not been enough research to-date on tree biomass spatial allocation and temporal dynamics in different site qualities at specific tree species scales. This study aimed to evaluate the biomass allocation patterns within tree components of Chinese fir and to examine how they are affected by tree age and site quality. A total of 87 trees were destructively sampled and measured for stem, branch, leaf, bark and root biomass. The biomass proportion difference of tree components in different age stages (8-40 years) was analysed, and the influence process of tree age and site quality on biomass allocation was examined. Our results indicate that the biomass allocation varied with tree age and was also affected by site quality. Stem biomass accounted for the largest proportion of total tree biomass, followed by leaf, root, branch and bark biomass in young forests, and it was followed by root, bark, branch and leaf biomass in other age groups. The biomass proportion of each component all nonlinearly changed with tree age. The proportion of stem biomass increased with increasing tree age, and the biomass proportion of branches and leaves decreased with increasing tree age. The proportion of root biomass first increased and then decreased with tree age, while the bark biomass proportion first decreased and then increased with increasing tree age. Site quality had a positive effect on the biomass proportion of stems but a negative effect on the biomass proportion of branches and bark. The interaction of tree age and site quality also had a significant effect on the proportion of stem biomass as well as root biomass. Therefore, to obtain accurate estimates of Chinese fir forest biomass and carbon stocks, age-specific changes and the influence of site conditions on it need to be considered.

Studying tree biomass dynamics and allocation is crucial to understanding the forest carbon cycle and the adaptation of trees to the environment. However, traditional biomass surveys are time-consuming and labor-intensive, so few studies have specifically examined biomass formation in terms of the increase in individual tree biomass, and the role that tree age and site conditions play in this process, especially tree roots, is unclear. We studied the tree ring characteristics of 87 sample trees (8–40 years old) from 29 Chinese fir plantations with different site conditions and measured the biomass of their stems, crowns, and roots. The biomass increment at various age stages during tree growth was determined via using tree ring analysis, and a generalized additive mixed model (GAMM) was used to analyze biomass formation and allocation, as well as the specific impact of site conditions on them. The results showed that the biomass increment of Chinese fir trees first increased and then decreased with age, and improving site conditions delayed the carbon maturation of the trees. The proportion of stem biomass increased with age, while the proportion of crown biomass decreased and the proportion of root biomass increased and then decreased. The effect of the site conditions on the tree biomass allocation showed a nonlinear trend. Tree ring analysis provides a feasible and effective method for assessing tree growth and biomass dynamics. Forest managers can use the findings of this study to scientifically optimize the management of increasing forest carbon sequestration.

Height–diameter (H–D) growth patterns describe the relative growth of tree height and stem diameter and may vary with local competitive conditions. We examined a Eucalyptus urophylla × E. grandis clone DH32-29 plantation across 12 stand units. Phenotypic comparisons included 364 interior trees and 254 true stand-edge trees; RNA-seq was conducted on a balanced subset of 72 trees (36 interior and 36 edge trees), not on the full phenotypic sample. Neighborhood competition around interior trees was characterized using the Hegyi index and basal area in larger trees (BAL), and growth traits were compared between interior and edge trees. Hegyi and BAL were negatively associated with growth, with stronger associations for diameter increment than for height increment. Unadjusted comparisons suggested different growth patterns, but plot-adjusted sensitivity analysis supported differences only in diameter increment and H/D. WGCNA identified modules associated with individual allometric traits, and XGBoost prioritized expression features with moderate model performance (R² = 0.404). qRT-PCR supported expression trends for selected genes but did not test gene function. These observational results identify associations among neighborhood structure, growth patterns, and gene-expression variation; edge contrasts may also reflect differences in light, wind exposure, microclimate, or soil conditions. The candidate modules and genes require independent and functional validation.