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

N1 - Publisher Copyright: © 2022 The Authors

PY - 2022

Y1 - 2022

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 - Journal article

AN - SCOPUS:85133741787

VL - 520

JO - Forest Ecology and Management

JF - Forest Ecology and Management

SN - 0378-1127

M1 - 120365

ER -