Tree biomass allometry during the early growth of Norway spruce (Picea abies) varies between pure stands and mixtures with European beech (Fagus sylvatica)

Abstract

Tree biomass allometry during the early growth of Norway spruce (Picea abies( AbstractIn this paper we report an investigation of how forest stand mixture may affect biomass allometric relationships in Norway spruce (Picea abies (L.) Karst). Analysis of aboveground biomass data was conducted for 50 trees. Twenty-five sample trees were from a pure Norway spruce stand and the remainder were taken from a mixed stand of Norway spruce with European beech (Fagus sylvatica L.). ANCOVA results demonstrated that individual tree biomass allometry of the pure stand significantly differed from that of the mixed stand. Allometric characteristics depended on the biomass component recorded and the type of biomass predictor used. When predicted by DBH and/or height, the total aboveground biomass of mixed stand trees was significantly less than that for pure stand ones. This 'apparent' lower aboveground biomass was attributed to the lower branch and needle biomass proportions of trees growing in mixed stands. The findings indicate that caution should be exercised when applying biomass allometric models developed from pure stands to predict tree biomass in mixed stands (and vice versa), as such data treatment may introduce significant bias.

A practical measure for determining if diameter (D) and height (H) should be combined into D2H in allometric biomass models

“…However, inclusion of H in the model would be of no value if D and H were perfectly correlated. Although D and H are always correlated to some degree, their relationship varies greatly (Feldpausch et al, 2010), being influenced by genotype, competition and environmental conditions (Egbäck et al, 2015;Hulshof et al, 2015;Dutcă et al, 2018b). As a result, including H in allometric models has been shown to improve biomass prediction accuracy (Chave et al, 2005(Chave et al, , 2014Feldpausch et al, 2012;Fayolle et al, 2013;Rutishauser et al, 2013;Dutcă et al, 2018a).…”

Site-effects on biomass allometric models for early growth plantations of Norway spruce (Picea abies (L.) Karst.)

“…The main drivers of site specificity in allometric models are H-D ratio, biomass allocation pattern (to vegetative organs) wood density, and these three are moderated by genotype [41], competition [42][43][44] and environmental conditions [27,[45][46][47]. Therefore, it can be expected that unique stand-level interactions between genotype, competition and environmental factors will influence H-D ratios, biomass allocation patterns and wood densities, and such stand level effects will be further reflected by the site-specificity of biomass allometric models.…”

“…In our sample, for any constant diameter, the H-D ratio was found to vary between sites (ICC = 0.77), thus strongly indicating that tree height was responsible for the high site-specificity of stem biomass component. In contrast, branch and needle biomass are less dependent on H-D ratio and may be more sensitive to competition with the neighbouring trees [42,49], which is why they exhibit greater within stand variability and, consequently, are less prone site-specific effects when modelled.…”

Biomass data for young, planted Norway spruce (Picea abies (L.) Karst.) trees in Eastern Carpathians of Romania

“…These two characteristics (i.e. tree architecture and wood density) are modulated by genotype [5] , tree competition [6] and environmental conditions [7] . Since wood density is inherently species specific and because the current dataset involves only one tree species, the sampling strategy has been focused on tree architecture only.…”