Interannual and spatial variation in maximum leaf area index of temperate deciduous stands

The aim of this study was to quantify, both spatial and temporal variations of maximum leaf area index (LAI) and to interpret LAI variation according to stand characteristics and meteorological conditions. We have compared ma ximum LAI, measured using the LI-COR LAI-2000 PCA, throughout 4 years and o ver 420 ha of a temperate forest across a range of stand structure (density , biomass, age) and site fertility (soil nutrient and water availability). LAI values ranged from 0.5 to 8 m(2) m(-2). This study has shown that maxim al LAI was relatively stable between years. However, although the water str ess did not affect LAI development in the current year, it reduced LAI of t he following year only in stands with high LAI (above 5.5 m(2) m(-2). spati al variations of maximal LAI were mainly dependent on forest management whi ch affected tree density and stand diameter at breast height (DBH) through thinning and harvesting. Among the 34 deciduous stands studied, maximal LAI increased with tree density up to a value of about 1000 stems per ha and t hen it reached a plateau between 6 and 8 m(2) m(-2). Total leaf area per tr ee has a strong correlation to DBH for species with different sap conductin g system (r(2) = 0.94). Decreases of maximal LAI with humus quality were ob served, suggesting that, although forest management appears to be the main cause of LAI variations between stands and between years, soil fertility ma y be a determinant of stand LAI. (C) 2000 Elsevier Science B.V. Allrights r eserved.