TY - JOUR
T1 - With increasing site quality asymmetric competition and mortality reduces Scots pine (Pinus sylvestris L.) stand structuring across Europe
AU - Pretzsch, Hans
AU - Bravo-Oviedo, Andrés
AU - Hilmers, Torben
AU - Ruiz-Peinado, Ricardo
AU - Coll, Lluís
AU - Löf, Magnus
AU - Ahmed, Shamim
AU - Aldea, Jorge
AU - Ammer, Christian
AU - Avdagić, Admir
AU - Barbeito, Ignacio
AU - Bielak, Kamil
AU - Bravo, Felipe
AU - Brazaitis, Gediminas
AU - Cerný, Jakub
AU - Collet, Catherine
AU - Drössler, Lars
AU - Fabrika, Marek
AU - Heym, Michael
AU - Holm, Stig Olof
AU - Hylen, Gro
AU - Jansons, Aris
AU - Kurylyak, Viktor
AU - Lombardi, Fabio
AU - Matović, Bratislav
AU - Metslaid, Marek
AU - Motta, Renzo
AU - Nord-Larsen, Thomas
AU - Nothdurft, Arne
AU - Ordóñez, Cristóbal
AU - den Ouden, Jan
AU - Pach, Maciej
AU - Pardos, Marta
AU - Ponette, Quentin
AU - Pérot, Tomas
AU - Reventlow, Ditlev Otto Juel
AU - Sitko, Roman
AU - Sramek, Vit
AU - Steckel, Mathias
AU - Svoboda, Miroslav
AU - Uhl, Enno
AU - Verheyen, Kris
AU - Vospernik, Sonja
AU - Wolff, Barbara
AU - Zlatanov, Tzvetan
AU - del Río, Miren
PY - 2022/9/15
Y1 - 2022/9/15
N2 - Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we revealed how the stand structure is determined by site quality and results from site-dependent partitioning of growth and mortality among the trees. We based our study on 90 mature, even-aged, fully stocked monocultures of Scots pine (Pinus sylvestris L.) sampled in 21 countries along a productivity gradient across Europe. A mini-simulation study further analyzed the site-dependency of the interplay between growth and mortality and the resulting stand structure. The overarching hypothesis was that the stand structure changes with site quality and results from the site-dependent asymmetry of competition and mortality. First, we show that Scots pine stands structure across Europe become more homogeneous with increasing site quality. The coefficient of variation and Gini coefficient of stem diameter and tree height continuously decreased, whereas Stand Density Index and stand basal area increased with site index. Second, we reveal a site-dependency of the growth distribution among the trees and the mortality. With increasing site index, the asymmetry of both competition and growth distribution increased and suggested, at first glance, an increase in stand heterogeneity. However, with increasing site index, mortality eliminates mainly small instead of all-sized trees, cancels the size variation and reduces the structural heterogeneity. Third, we modelled the site-dependent interplay between growth partitioning and mortality. By scenario runs for different site conditions, we can show how the site-dependent structure at the stand level emerges from the asymmetric competition and mortality at the tree level and how the interplay changes with increasing site quality across Europe. Our most interesting finding was that the growth partitioning became more asymmetric and structuring with increasing site quality, but that the mortality eliminated predominantly small trees, reduced their size variation and thus reversed the impact of site quality on the structure. Finally, the reverse effects of mode of growth partitioning and mortality on the stand structure resulted in the highest size variation on poor sites and decreased structural heterogeneity with increasing site quality. Since our results indicate where heterogeneous structures need silviculture interventions and where they emerge naturally, we conclude that these findings may improve system understanding and modelling and guide forest management aiming at structurally rich forests.
AB - Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we revealed how the stand structure is determined by site quality and results from site-dependent partitioning of growth and mortality among the trees. We based our study on 90 mature, even-aged, fully stocked monocultures of Scots pine (Pinus sylvestris L.) sampled in 21 countries along a productivity gradient across Europe. A mini-simulation study further analyzed the site-dependency of the interplay between growth and mortality and the resulting stand structure. The overarching hypothesis was that the stand structure changes with site quality and results from the site-dependent asymmetry of competition and mortality. First, we show that Scots pine stands structure across Europe become more homogeneous with increasing site quality. The coefficient of variation and Gini coefficient of stem diameter and tree height continuously decreased, whereas Stand Density Index and stand basal area increased with site index. Second, we reveal a site-dependency of the growth distribution among the trees and the mortality. With increasing site index, the asymmetry of both competition and growth distribution increased and suggested, at first glance, an increase in stand heterogeneity. However, with increasing site index, mortality eliminates mainly small instead of all-sized trees, cancels the size variation and reduces the structural heterogeneity. Third, we modelled the site-dependent interplay between growth partitioning and mortality. By scenario runs for different site conditions, we can show how the site-dependent structure at the stand level emerges from the asymmetric competition and mortality at the tree level and how the interplay changes with increasing site quality across Europe. Our most interesting finding was that the growth partitioning became more asymmetric and structuring with increasing site quality, but that the mortality eliminated predominantly small trees, reduced their size variation and thus reversed the impact of site quality on the structure. Finally, the reverse effects of mode of growth partitioning and mortality on the stand structure resulted in the highest size variation on poor sites and decreased structural heterogeneity with increasing site quality. Since our results indicate where heterogeneous structures need silviculture interventions and where they emerge naturally, we conclude that these findings may improve system understanding and modelling and guide forest management aiming at structurally rich forests.
KW - Asymmetry of competition
KW - Gini coefficient
KW - Growth dominance coefficient
KW - Mode of competition
KW - Size-dependent mortality
KW - Structural heterogeneity
U2 - 10.1016/j.foreco.2022.120365
DO - 10.1016/j.foreco.2022.120365
M3 - Article
AN - SCOPUS:85133741787
SN - 0378-1127
VL - 520
JO - Forest Ecology and Management
JF - Forest Ecology and Management
M1 - 120365
ER -