Relations between pedunculate oak growth and climate on two types of temporarily waterlogged soils [acidic redoxisol and pelosol] in the Lorraine region.

摘要

The behaviour of 30-year-old pedunculate oak trees growing in Lorraine on two different waterlogged soils (acidic redoxisol and pelosol) was studied. To reduce the constraints arising from excess water during autumn and winter, different drainage techniques were tested (ridge drainage, trenches 10 or 20 m apart). The study focussed on the effects of soil and drainage on the radial growth and on sensitivity to annual weather conditions. On redoxisol, growth was greater by about 10-15% related to a more moderate groundwater regime (in duration and in intensity) and to deeper root development (altered spatial distribution). Even if extreme frosts in winter caused significant growth reductions in both ecological circumstances, sensitivity to climate appeared higher and after-effects more pronounced on redoxisol (period of study: 1975-2005). In this situation, a humid and fresh autumn (October and November) the previous year followed by a rather hot and dry spring (May) tends to give rise to a wide ring. In the case of the pelosol, sensitivity to weather conditions and climatic after-effects are less noticeable. A wide ring is produced when the end of the summer (September) of the previous year is cool, followed by a rather cool and wet onset of the current summer (June). Drainage was not found to have any influence in the response to annual weather conditions in either circumstance. Finally, the findings are discussed in the light of our partial knowledge of the functioning of these soils and of the ecophysiological characteristics of the species.