A spatially explicit model of leaf litter fall in hemlock–hardwood forests

摘要: A spatially explicit model of leaf litter fall was developed for hemlock–hardwood forests using litter-trap data from mapped forest plots and from isolated trees. The model assumes that litter declines exponentially with distance, as shown by the litter traps from isolated trees, and that a variable allometric equation describes the relationship of DBH to foliage biomass. Model parameters were estimated by a maximum likelihood method using field data from one mapped plot and then tested on a second plot. Predicted leaf fall of sugar maple (Acersaccharum Marsh.), yellow birch (Betulaalleghaniensis Britton), basswood (Tiliaamericana L.), and eastern hemlock (Tsugacanadensis (L.) Carrière) was consistent with the leaf fall measured in 20 traps (r = 0.86, 0.77, 0.95, 0.92, respectively). Data from 100 paired litter traps show the similarity of litter fall at sites 2.7 m apart; trap contents in two successive autumns were also comparable. The model results show that hemlock has the narrowest leaf-fall shadow, while basswood has the broadest. The average radius within which 90% of the leaf litter fall to a trap originates is 17.1 m. A litter fall model can be used to predict nutrient inputs to the forest floor based on a stem map, and strengthens links between population and ecosystem ecology.