Adjustment of the age–height relationship for uneven-aged black spruce stands

Abstract

Site index (SI) is commonly used in natural stands, even when their diameter distribution deviates from that of the monospecific, even-aged, fully stocked stands used to develop basic age–height relationships. Since deviations from basic age–height trajectories can be reflected in deviations of stand diameter distribution from a bell shape, we incorporated different diameter diversity indices into an age–height equation to help improve height predictions and determine which index is best related to stand dominant height. This procedure was performed using black spruce ( Picea mariana (Mill.) BSP) stands from a large network of permanent sample plots established across the province of Quebec, Canada. The age–height model that minimized the Akaike’s information criterion used the Shannon evenness index (ESh) as an equation modifier accounting for the diameter diversity variable. The model showed that for stands established on relatively poor sites (SI = 9), no substantial differences in dominant height were found between two contrasting ESh values. For SI = 15, however, the larger ESh value increased the dominant height by as much as 1 m at 80 years. These results suggest that introduction of ESh into an age–height model can improve calculation of site index, particularly in regions characterized by the presence of numerous uneven-aged stands.

HEIGHT-DIAMETER RELATIONSHIPS FOR Araucaria angustifolia (BERTOL.) KUNTZE IN SOUTHERN BRAZIL

“…These results are in accordance with the values observed in the literature in terms of accuracy and precision (HUANG et al, 2000;COLBERT et al, 2002;PENG et al, 2004;ADAME et al, 2008;OUZENNOU et al, 2008;LEI et al, 2009;CRECENTE-CAMPO et al, 2010).…”

Predicting the long-term yield trajectory of black spruce stands using time since fire

“…The H d value calculated for each measurement of each PSP was then incorporated into the age-height relationship developed by Ouzennou et al (2008) for black spruce stands:…”

“…Eqs. (2)-(7) were used in order to take into account the indirect effect of diameter diversity (E Sh ) on the age-height relationship, which is particularly important for adjusting site index estimation of old, irregularly structured stands according to Ouzennou et al (2008).…”

“…Yield models are generally calibrated with numerous inventory plots that adequately represent changes in volume from juvenile stage to maturity. After maturity, however, the information available on the pattern of change in merchantable volume is generally uncertain because as dominant trees begin to die through natural senescence, it becomes increasingly harder to sample free-growing dominant trees that represent the correct stand age and dominant height (Ouzennou et al, 2008), two key variables of most stand-level yield models. The phase in which mortality begins to affect the initial post-disturbance cohort of trees while younger trees reach the canopy is known as the old-growth stage (Kneeshaw and Gauthier, 2003).…”

Spatial Autoregressive Models for Stand Top and Stand Mean Height Relationship in Mixed Quercus mongolica Broadleaved Natural Stands of Northeast China

“…Estimating site productivity is crucial to predict forest growth and yield, as well as to maintain sustainable management of forest resources [2,3]. Site index, which is commonly defined as the mean height of dominant and codominant trees of a stand (hereafter referred to as stand top height) at a pre-specified age [4][5][6], has been accepted and widely used as the most expedient indicator of forest site productivity in Germany and North America since around the end of the 19th century because of its simple calculation and efficacious prediction [3,6,7]. Additionally, stand top height is less sensitive to thinning and allows more stability of assessment (e.g., [6,8,9]), and invariance with stand density (e.g., [1,10,11]).…”