Search

Close-to-nature management (CTNM) has been proposed as a promising forestry management approach to improve the structure and quality of forests, which integrates wood production and ecological service functions. Research on the effect of CTNM on the univariate and bivariate distribution of the spatial structure of forest stands provides a scientific basis for the evaluation of CTNM implemented in forestry. Here, we analyzed and compared the spatial-structure characteristics of Masson pine (Pinus massoniana) plantations (young, middle-age, and near-mature stages) under CTNM 8 years after selective cutting and unmanaged control. We used univariate and bivariate distribution of three spatial-structure parameters: mingling (M), dominance (U), and uniform-angle index (W). Results showed that the effect of CTNM on spatial structure was more remarkable in middle-aged and near-mature Masson pine forests compared with the young forest. CTNM significantly improved mingling degree and promoted the horizontal distribution, thereby changing from a cluster to a random distribution. Moreover, CTNM improved the proportion of trees with a high mixing degree and random distribution and the proportion of trees having a micro-structure of random distribution with a high degree of mixture and dominance with a high degree of mixture in middle-aged and near-mature Masson pine forest. Overall, the implementation of CTNM 8 years ago showed a positive effect on the improvement of the spatial structure of Masson pine forest, but the present spatial structure is suboptimal. Further implementation of CTNM to adjust the mingling and uniform-angle index is necessary, and CTNM according to this method of frequency distribution of stand structure parameters can improve the success of forest management.

The relationship between height and diameter (H-D) is an important component in forest growth and yield models, and a better understanding of the relationship will improve forest monitoring, management, and biomass estimation. Sixteen nonlinear growth functions were fitted to H-D data for 1261 trees from a Cryptomeria fortunei plantation in the Pingba region of Guizhou Province, China. Of the 1261 trees, 80 % were randomly selected for model calibration, while the remaining trees were reserved for model validation. All models were evaluated and compared by means of multiple-model performance criteria. Although all 16 models showed a good fit to the dataset and each of them accounted for more than 75 % of the total variation in height, a large difference in asymptotic estimates was observed. The Chapman–Richards, Weibull, and Näslund models were recommended for C. fortunei plantations, due to their satisfactory height prediction and biological interpretability.

This study investigated a typical pine-oak mosaic mixed forest in the Qinling Mountains, China. In the sample plot, the population structure and spatial distribution of the stems were analyzed for the predominant species, to identify the mechanisms of species coexistence and successional trends of the forest. The population structures of all species were bimodally distributed, with young trees (DBH

This paper attempts to explore the characteristics of the spatial structure and development dynamics of three predominant tree populations, Quercus aliena var. acutiserrata Maxim.(QA), Acer caesium subsp. giraldii (Pax) E. Murr.(AC), and Ulmus propinqua Koidz (U. japonica) Sag (UG), in a virgin old-growth oak broad-leaved mixed forest in the Qinling Mountains, China. We employed a bivariate distribution of the structural parameters (mingling, dominance, and uniform angle index) based on the relationship between nearest neighbor tree groups and found that all predominant populations with a high species mixture and random distribution pattern. However, QA and UG are recessional populations, and AC is a progressive population. Predominant populations showed a consistent tendency during stand development that the spatial structures became increasingly mixed; the distribution pattern gradually transformed from clumped to random, and the segregation among the tree species increased. This finding demonst...

Understanding the factors that allow the successful regeneration of species is a key step toward the conservation and management of forests. In this study, canonical correspondence analysis was used to examine the relationships between the distribution of the regenerating species in pine-oak mixed forests and 18 environmental factors of topography, soil properties, and forest characteristics in seedlings and saplings in the Qinling Mountains in China. A generalized additive model was used to fit the response of the density of the regenerating species to the various environmental factors. Variation partitioning in both seedling and sapling stories indicated that the order of importance was soil properties > forest characteristics > topography. The distribution of seedlings and saplings was mainly influenced by slope gradient, shrub cover, and available phosphorus. Herb cover and total nitrogen level were major environmental factors affecting the density of the regenerating seedlings, but total pota...