Long-term growth trends of Fagus sylvatica L. in northeastern France. A comparison between high and low density stands

摘要

Several recent surveys have shown an increasing long-term growth trend for various forest species in western Europe. In order to confirm these growth changes and to study the role of stand density changes, we compared radial growth trends of beech (Fagus sylvatica L.) in northeastern France, during the last century, in two different silvicultural systems: high forest (high density stands) and coppice-with-standards (low density stands). The sampling scheme was based on 1025 trees of all age classes from 102 sites. This allowed the separation, in the low-frequency signals, of effects related to the ageing of the trees or stands from other effects. Two standardization techniques were used. Both showed a significant increasing radial growth trend since the last century, independent from biological effects related to age. However, this trend was steeper and began earlier in high forest than in coppice-with-standards stands. This result implies that the current increasing growth trend is partly due to silvicultural effects or interactions between silviculture and environmental changes.