Influence of nurse birch and Scots pine seedlings on early aerial development of European beech seedlings in an open-field plantation of Central France
1 Cemagref, Research Unit on Mediterranean Ecosystems and Risks, 3275 route Cézanne, CS40 061, F-13182 Aix-en-Provence Cedex 5, France
2 Cemagref, Sustainable Management and Biodiversity of Forest Ecosystems, Domaine des Barres, F-45290 Nogent-sur-Vernisson, France
* Corresponding author. E-mail: bernard.prevosto{at}aix.cemagref.fr
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Abstract |
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Beech woodland can be restored by direct planting of beech (Fagus sylvatica L.) seedlings in abandoned areas, but this method is generally avoided in forestry because of the growth difficulties of beech in full-light conditions. This study tested a method that consists of planting beech seedlings in full-light conditions with silver birch (Betula pendula Roth.) or Scots pine (Pinus sylvestris L.) as nurse trees. A total of 65 two-year-old beech seedlings surrounded by either 3, 4, 5 or 6 pine or birch seedlings or without competitors were planted in bare-soil open-field conditions in Central France. Tree growth and light availability were monitored at the end of each of the following 3 years, and soil moisture was also measured the last year. At the end of the experiment, aerial biomass measurements were made on the beeches. Results showed that relative beech growth in terms of diameter was significantly reduced by the local neighbouring trees and that this reduction was particularly noticeable in the pine treatments where there was extensive pine seedling development. In contrast, relative beech height did not exhibit any significant variations among the treatments. Light availability was decreased by the neighbouring trees, especially in the pine treatments. Light reduction was more pronounced in the last 2 years and in the middle or lower parts of the canopy of the subject beech. Soil water content was lower under the pine canopies than under the birch canopies, and was positively correlated to beech relative diameter growth. Specific leaf area, height-to-diameter ratio and crown length-to-crown width ratio weakly but significantly increased with competition from the neighbours. Beech biomass partitioning was only weakly affected by the treatments. This study showed that nurse trees tend to reduce beech growth but improve form although effects remained weak due to the insufficient length of the experiment. Further studies are also needed to quantify the effects of the neighbourhood on the growth of competitive herbaceous vegetation and on changes in the microclimatic conditions.
Received 14 September 2006.
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