Variability in the climate-radial growth correlation of Pinus massoniana of different diameter classes

The physiological characteristics of trees change with age,suggesting that growth-related climate signals vary over time.This study aimed to clarify the impacts of different diameter classes on the chronological characteristics of Pinus massoniana Lamb.and its response to climatic factors.Chronologies of P inus massoniana were established in small diameter(14.1 cm),middle diameter(27.3 cm),and large diameter(34.6 cm)trees according to dendrochronology.The results show that:(1)radial growth of different diameter classes had varied characteristics and climate sensitivities;(2)radial growth of small diameter trees was affected by climatic factors of the previous and the current year,while large diameter trees were mainly affected by climatic factors of the current year;and(3)precipitation and temperature were key factors that restricted the radial growth of small and large diameter trees,respectively.

Influence of Spatial Distribution on the Regeneration of <i>Piptadeniastrum africanum</i>and <i>Ocotea usambaernsis</i>in Kalikuku, Lubero, North Kivu, Democratic Republic of Congo

The aim of our study is to highlight the spatial structure of the trees and to determine its influence on the natural regeneration of the Kalikuku dense forest, with a view of its optimal conservation and enhancement. Data collection was done by measuring diameter at breast height along 10 plots of 0.5 ha in size. In analyzing these data, the Dajoz test was used to determine the horizontal spatial distribution pattern of the two most abundant tree species in the forest (Piptadeniastrum africanum and Ocotea usambarensis). The χ2 test was used to compare the frequency distribution of diameter classes for the two species tested. To estimate the difference between the number of seedlings in aggregate versus non-aggregate areas, the Wilcoxon signed-rank test was used. In addition, the equability index was used to test the preponderance of proportions between diameter classes. Finally, the natural regeneration index was evaluated.

Are models of volumetric production at the diametric distribution and total stand level mutually compatible?

The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory.The model efficiency was also evaluated.Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand,comprising 24 sample plots used for model fitting,and six sample plots for validation.The volume of wood per hectare was estimated for different productive units(sites),using 7 years as the reference age.The model adjustment quality was verified by adjustment and precision statistics:the correlation between observed and predicted variables,root mean square error percentage,graphical analysis of residual distribution,and a frequency histogram for classes of relative errors and validation.Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age(7 years)in the different productivity classes,it generated imprecise estimates of the number of individuals.Consequently,it produced inaccurate volumetric production estimates.The total stand model provided reliable projections of production volumes in different productivity classes for both adjustment types,showing compatibility with the pre-cut inventory according to a Tukey test.In summary,the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not.