Effect of species proportion definition on the evaluation of growth in pure vs. mixed stands.
By Hubert Sterba, M. Río, A. Brunner, S. Condés. 2014
59 citations recorded by the source corpus.
Aim of study : The aim of this paper is to compare differences in growth per hectare of species in pure and mixed stands as they result from different definitions of species proportions. Area of Study : We used the data of the Spanish National Forest Inventory for Scots pine and beech mixtures in the province of Navarra and for Scots pine and Pyrenean oak mixtures in the Central mountain range and the North Iberic mountain range. Material and Methods : Growth models were parameterized with the species growth related to its proportion as dependent variable, and dominant height, quadratic mean diameter density, and species proportion as independent variables. As proportions we use once proportions by basal area or by stand density index and once these proportions considering the species specific maximum densities. Main Results : In the pine – beech mixtures, where the maximum densities do not differ very much between species, the mixing effects are very similar, independent of species proportion definitions. In the pine – oak mixture, where the maximum densities in terms of basal area are very different, the equations using the proportions calculated without reference to the maximum densities, result in a distinct overestimation of the mixing effects on growth. Research highlights : When comparing growth per hectare of a species in a mixed stand with that of a pure stand, the species proportion must be described as a proportion by area considering the maximum density for the given species, wrong mixing effects could be introduced by inappropriate species proportion definitions. Keywords: Mixing effects; proportion by area; Stand Density Index; overyielding; Pinus sylvestris L.; Fagus sylvatica L.; Quercus pyrenaica Willd.
Subfields: Global and Planetary Change, Mechanics of Materials, Nature and Landscape Conservation
View Paper: https://www.semanticscholar.org/paper/566fe6c8aef9133ff3f2afa14f63b1edaa9c45bf
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In Global and Planetary Change
In Mechanics of Materials
In Nature and Landscape Conservation
Citations in the corpus
- Tree species mixing can increase maximum stand density (2016, background): “…specific growing space requirements from the SDI as shown above is not 236 only a key to species-independent stand density comparisons, but also to calculating the area 237 proportions of the different species in a mixed stand (Dirnberger & Sterba 2014, Huber et al. 238 2014, Sterba et al. 2014).”
- Tamm Review: On the strength of evidence when comparing ecosystem functions of mixtures with monocultures (2015, methodology): “fo or basal area) and tree size (using SDI) when calculating mixing proportions (Río and Sterba, 2009; Condés et al., 2013; Sterba et al., 2014).”
- Characterization of the structure, dynamics, and productivity of mixed-species stands: review and perspectives (2015, methodology): “Another option is based on quantifying the proportion of the stand area occupied by each species, reducing 3D growing space into 2D (Sterba 1998; Sterba et al. 2014).”
- Improved productivity and modified tree morphology of mixed versus pure stands of European beech (Fagus sylvatica) and Douglas-fir (Pseudotsuga menziesii) with increasing precipitation and age (2016, methodology): “The stand density differences between the species were adjusted by an equivalence coefficient e1 computed by the ratio between the SDI of pure Douglas-fir stands (SDIDf) and pure beech stands (SDIEb) (Sterba et al. 2014; Pretzsch et al. 2015).”