TY - JOUR

T1 - Effects of local neighbourhood diversity on crown structure and productivity of individual trees in mature mixed-species forests

AU - Georgi, Louis

AU - Kunz, Matthias

AU - Fichtner, Andreas

AU - Reich, Karl Friedrich

AU - Bienert, Anne

AU - Maas, Hans-Gerd

AU - von Oheimb, Goddert

N1 - Funding Information: LG was funded by the German Research Foundation (DFG 320926971) through the project “Analysis of diversity effects on above-ground productivity in forests: advancing the mechanistic understanding of spatio-temporal dynamics in canopy space filling using mobile laser scanning”. Funding Information: We thank the Forestry Offices of the City of Lübeck County for permission to conduct this study in their forests. The QSM calculations were made on the Taurus HPC cluster of the ZIH of the TU Dresden. Moreover, we would like to thank the anonymous reviewers for their comments and suggestions on the manuscript. Publisher Copyright: © 2021, The Author(s).

PY - 2021/4/26

Y1 - 2021/4/26

N2 - Background: Species-specific genotypic features, local neighbourhood interactions and resource supply stronglyinfluence the tree stature and growth rate. In mixed-species forests, diversity-mediated biomass allocation has beensuggested to be a fundamental mechanism underlying the positive biodiversity-productivity relationships. Empiricalevidence, however, is rare about the impact of local neighbourhood diversity on tree characteristics analysed at avery high level of detail. To address this issue we analysed these effects on the individual-tree crown architectureand tree productivity in a mature mixed forest in northern Germany. Methods: Our analysis considers multiple target tree species across a local neighbourhood species richnessgradient ranging from 1 to 4. We applied terrestrial laser scanning to quantify a large number of individual maturetrees (N= 920) at very high accuracy. We evaluated two different neighbour inclusion approaches by analysing botha fixed radius selection procedure and a selection based on overlapping crowns. Results and conclusions: We show that local neighbourhood species diversity significantly increases crowndimension and wood volume of target trees. Moreover, we found a size-dependency of diversity effects on treeproductivity (basal area and wood volume increment) with positive effects for large-sized trees (diameter at breastheight (DBH) > 40 cm) and negative effects for small-sized (DBH < 40 cm) trees. In our analysis, the neighbourinclusion approach has a significant impact on the outcome. For scientific studies and the validation of growthmodels we recommend a neighbour selection by overlapping crowns, because this seems to be the relevant scaleat which local neighbourhood interactions occur. Because local neighbourhood diversity promotes individual-treeproductivity in mature European mixed-species forests, we conclude that a small-scale species mixture should beconsidered in management plans.

AB - Background: Species-specific genotypic features, local neighbourhood interactions and resource supply stronglyinfluence the tree stature and growth rate. In mixed-species forests, diversity-mediated biomass allocation has beensuggested to be a fundamental mechanism underlying the positive biodiversity-productivity relationships. Empiricalevidence, however, is rare about the impact of local neighbourhood diversity on tree characteristics analysed at avery high level of detail. To address this issue we analysed these effects on the individual-tree crown architectureand tree productivity in a mature mixed forest in northern Germany. Methods: Our analysis considers multiple target tree species across a local neighbourhood species richnessgradient ranging from 1 to 4. We applied terrestrial laser scanning to quantify a large number of individual maturetrees (N= 920) at very high accuracy. We evaluated two different neighbour inclusion approaches by analysing botha fixed radius selection procedure and a selection based on overlapping crowns. Results and conclusions: We show that local neighbourhood species diversity significantly increases crowndimension and wood volume of target trees. Moreover, we found a size-dependency of diversity effects on treeproductivity (basal area and wood volume increment) with positive effects for large-sized trees (diameter at breastheight (DBH) > 40 cm) and negative effects for small-sized (DBH < 40 cm) trees. In our analysis, the neighbourinclusion approach has a significant impact on the outcome. For scientific studies and the validation of growthmodels we recommend a neighbour selection by overlapping crowns, because this seems to be the relevant scaleat which local neighbourhood interactions occur. Because local neighbourhood diversity promotes individual-treeproductivity in mature European mixed-species forests, we conclude that a small-scale species mixture should beconsidered in management plans.

KW - Ecosystems Research

KW - biodiversity

KW - tree growth

KW - crown architecture

KW - quantitative structure models

KW - terrestrial laser scanning

KW - neighbour classification

KW - Biodiversity

KW - Tree growth

KW - Crown architecture

KW - Quantitative Structure Models

KW - Terrestrial laser scanning

KW - neighbour classification

UR - http://www.scopus.com/inward/record.url?scp=85104880943&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/72464af0-dcb8-39ea-a019-96cc23502437/

U2 - 10.1186/s40663-021-00306-y

DO - 10.1186/s40663-021-00306-y

M3 - Journal articles

VL - 8

JO - Forest Ecosystems

JF - Forest Ecosystems

SN - 2095-6355

IS - 1

M1 - 26

ER -