Abstract
In pure and mixed stands of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) we have analyzed crown allometry and growing space efficiency at the tree level and have scaled this from tree level to stand level production. Allometry is quantified by the ratio A between the relative growth rates of laterally and vertically oriented tree dimensions. Efficiency parameters, EOC for efficiency in space occupation, EEX for efficiency in space exploitation, and EBI for efficiency in biomass investment, were evaluated, based on quantity and quality of growing space and were measured using crown size and competition index. The evaluation reveals why pure stands of spruce are preferred by foresters, even though the natural vegetation would be dominated by beech. Spruce occupies its share of resources intensively by means of tightly packed pillar-like crowns, whereas beech seizes resources extensively by means of a multi-layered, veil-like canopy. With a given relative biomass increment, beech achieves a 57 % higher increment in crown projection area and a 127 % higher increment in height due to its particular capacity of lateral and vertical expansion. Beech trees are approximately 60 % more efficient in space occupation than spruce trees, however, on average, they are about 70 % less efficient in space exploitation. As a vertical fast growing tree, spruce is efficient in space exploitation under constant conditions, but far more susceptible to disturbances and less well equipped to overcome them when compared with beech. Beech is weaker in terms of space exploitation, while being superior in space occupation, where it encircles competitors and fills gaps after disturbances, which is a successful long-term strategy. A mixture of the two species reduces stand level production by 24 % in comparison to a pure spruce stand, however, when considering enhanced stabilization of the whole stand and risk distribution in the long term, the mixed stand may exceed the production level of pure spruce stands. EEX reflects a strong ontogenetic drift and competition effect that should be considered when scaling from tree to stand level production.
Key words
Crown allometry - growing space efficiency - Norway spruce - European beech - mixed stand - competition index - scaling from tree to stand level
References
Fagus sylvatica L.) and Norway spruce (Picea abies [L.] Karst.).
Plant and Soil.
(2004);
264
1-11
Implication of forest diversity for the resistance to strong winds. Scherer-Lorenzen, M., Körner, C., and Schulze, E.-D., eds. Forest Diversity and Function, Ecological Studies 176. Berlin; Springer (2004): 399p
An introduction to the functional diversity of temporate forest trees. Scherer-Lorenzen, M., Körner, C., and Schulze, E.-D., eds. Forest Diversity and Function, Ecological Studies 176. Berlin; Springer (2005): 13-37
Aspects of stability, growth and natural regeneration in mixed Norway spruce-beech stands as a basis of silvicultural decisions. Olsthoorn, A. F. M., Bartelink, H. H., Gardiner, J. J., Pretzsch, H., Hekhuis. H. J., and Franc, A., eds. Management of Mixed-Species Forest: Silviculture and Economics, IBN Scientific Contributions. (1999): 245-267
Diversity and productivity in forests. Scherer-Lorenzen, M., Körner, C., and Schulze, E.-D., eds. Forest Diversity and Function, Ecological Studies 176. Berlin; Springer (2004): 41-64
Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.): evidence from long-term experimental plots.
European Journal of Forest Research.
(2005 b);
DOI: 10.1007/s10342-005-0068-4
(Pinus taeda) spacing experiment.
Canadian Journal of Forest Research.
(1998);
28
1344-1351
h.pretzsch@lrz.tum.de
Guest Editor: R. Matyssek
