Precipitation water storage capacity in a temperate mixed oak-beech canopy

The storage capacity of a temperate mixed oak-beech stand was investigated as a function of stand density and species composition. Measurements were performed in selected zones delimited by three neighbouring trees. Three independent approaches were compared: (i) a spraying laboratory experiment to estimate the water storage on foliage before and after dripping: (ii) a mechanistic model deseribing, rainfall partitioning within the forest canopy and providing, estimates of foliage storage capacities: and (iii) linear regression analyses to evaluate the canopy (foliage + branches) storage capacity using the relationship between throughfall and rainfall. Good agreement was generally observed between the laboratory experiment and the mechanistic model estimates. while estimations from the regression method tended to exceed those from the other approaches. Storage capacity estimates ranged from 0.22 mm to 0.80 mm for pure oak zones, from 0.24 mm to 1.12 mm for mixed zones and from 0.53 mm to 1.17 mm for pure beech zones. The increase of storage capacity with increasing proportion of beech in the canopy resulted from higher beech LAI compared with oak. Similarly, for mixed and pure beech canopies. storage capacity was higher for high density zones than for low density zones as a result of the increase in LAI with increasing local basal area: in contrast, for pure oak, the storage capacity was not related to basal area because of the lower shade-tolerance of this species compared with beech. Copyright (C) 2008 John Wiley & Sons, Ltd.