Structure and growth of mixed Scots pine/European beech stands compared with pure stands analyzed along an ecological gradient through Europe

• Applicant: Professor Dr. Hans Pretzsch
• Subject Area: Forestry
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280969003

• Final Report Year: 2023

Final Report Abstract

Our work is based on a series of research plots “triplets” of two of the most common tree species in Europe - European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) - along an ecological gradient through four European countries. These triplets were used to trace properties from the organ to stand level, combining analysis of structural and functional traits in order to clarify and improve theory of forest mixing beyond different ecosystems, model approaches, and prediction. Our results confirm the benefit of mixing deciduous, conifer species, showing that functional - leaf area, leaf, branches, and stem mass, etc. - and structural traits - crown length, projected area, wood density, etc. - behave differently in mixed and monospecific. These differences are expressed in terms of biomass allocation, light interception, water efficiency, and wood composition. The assessment of the latter two characteristics confirmed the stability of the benefits of mixing through time, which is of significant importance in the current climatic scenario. The assumptions and hypotheses presented through our project can carefully be extrapolated to other species in mixture that are similar in terms of light complementarity. These specific findings are relevant for forest management as they provide quantitative evidence of the implications of defining productivity of a forest stand in ecological or economic terms. Moreover, they contribute to policy-makers to take better informed decisions on aspects like carbon storage, to be used in global agreements in order face the current climatic scenario. The data collected in the frame of the project is available for additional research work. Our most interesting finding was that in pine stands the growth partitioning becomes 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.

Publications

• Canopy space filling and tree crown morphology in mixed-species stands compared with monocultures. Forest Ecology and Management, 327, 251-264.
  Pretzsch, Hans
  
• A New Method to Reconstruct Recent Tree and Stand Attributes of Temporary Research Plots: New Opportunity to Analyse Mixed Forest Stands. Conifers.
  Heym, Michael; Bielak, Kamil; Wellhausen, Klaas; Uhl, Enno; Biber, Peter; Perkins, Diana; Steckel, Mathias; Andreas, Thurm Eric; Rais, Andreas & Pretzsch, Hans
  
• Estimation and Uncertainty of the Mixing Effects on Scots Pine—European Beech Productivity from National Forest Inventories Data. Forests, 9(9), 518.
  Condés, Sonia; Sterba, Hubert; Aguirre, Ana; Bielak, Kamil; Bravo-Oviedo, Andrés; Coll, Lluís; Pach, Maciej; Pretzsch, Hans; Vallet, Patrick & Del Río, Miren
  
• Maintenance of long-term experiments for unique insights into forest growth dynamics and trends: review and perspectives. European Journal of Forest Research, 138(1), 165-185.
  Pretzsch, Hans; del Río, Miren; Biber, Peter; Arcangeli, Catia; Bielak, Kamil; Brang, Peter; Dudzinska, Malgorzata; Forrester, David Ian; Klädtke, Joachim; Kohnle, Ulrich; Ledermann, Thomas; Matthews, Robert; Nagel, Jürgen; Nagel, Ralf; Nilsson, Urban; Ningre, François; Nord-Larsen, Thomas; Wernsdörfer, Holger & Sycheva, Ekaterina
  
• 2019b. Weiterentwicklung der Dichte- und Mischungsregulierung forstwirtschaftlich wichtiger Baumarten. Ãquivalenz-Koeffizienten und Dichte-Steigerungs- Koeffizienten für generische waldbauliche Behandlungsalgorithmen. Allg.Forst-u.J.-Ztg. 190(3/4)
  Pretzsch, H.
  
• 2020b. Zuwachsniveau, Zuwachstrend und episodische Zuwachseinbrüche. Ein zusammenfassendes Bild vom aktuellen Zuwachsgang in Rein- und Mischbeständen aus Fichte, Kiefer, Buche und Eiche. AFJZ,Vol. 191
  Pretzsch, H.; Ammer, C.; Wolff, B.; Steckel, M.; Rukh, S. & Heym, M.
  
• Growth and mortality of Norway spruce and European beech in monospecific and mixed-species stands under natural episodic and experimentally extended drought. Results of the KROOF throughfall exclusion experiment. Trees, 34(4), 957-970.
  Pretzsch, H.; Grams, T.; Häberle, K. H.; Pritsch, K.; Bauerle, T. & Rötzer, T.
  
• Do trees have constant branch divergence angles?. Journal of Theoretical Biology, 512, 110567.
  Beyer, Robert M.; Basler, David; Raumonen, Pasi; Kaasalainen, Mikko & Pretzsch, Hans
  
• Tree species mixing can increase stand productivity, density and growth efficiency and attenuate the trade-off between density and growth throughout the whole rotation. Annals of Botany, 128(6), 767-786.
  Pretzsch, H. & Schütze, G.
  
• Facilitation and competition reduction in tree species mixtures in Central Europe: Consequences for growth modeling and forest management. Ecological Modelling, 464, 109812.
  Pretzsch, Hans
  
• Linking crown structure with tree ring pattern: methodological considerations and proof of concept. Trees, 36(4), 1349-1367.
  Pretzsch, Hans; Ahmed, Shamim; Jacobs, Martin; Schmied, Gerhard & Hilmers, Torben
  
• With increasing site quality asymmetric competition and mortality reduces Scots pine (Pinus sylvestris L.) stand structuring across Europe. Forest Ecology and Management, 520, 120365.
  Pretzsch, Hans; Bravo-Oviedo, Andrés; Hilmers, Torben; Ruiz-Peinado, Ricardo; Coll, Lluís; Löf, Magnus; Ahmed, Shamim; Aldea, Jorge; Ammer, Christian; Avdagić, Admir; Barbeito, Ignacio; Bielak, Kamil; Bravo, Felipe; Brazaitis, Gediminas; Cerný, Jakub; Collet, Catherine; Drössler, Lars; Fabrika, Marek; Heym, Michael ... & del Río, Miren