Weight and Calcium losses from decomposing tree leaves on land and in water.
Losses of weight and Ca from decomposing leaves of Acer rubrum, Liriodendron tulipifera and Quercus alba proceeded at much greater rates in a perennial stream than they did on land. Complete decomposition of Acer leaves in water required <24 weeks, while that of Liriodendron and Quercus both required <44 weeks. First-year losses on land also varied among species: from Acer losses were 55% of weight and 54% of Ca; from Liriodendron, 44% of weight and 38% of Ca; and from Quercus, 33% of weight and 35% of Ca. Constant leaching and scouring of leaves by bottom sediments probably accounted for the greater loss rates in water. Variation in weight and Ca losses among samples in the stream far exceeded the variation among samples on land. Weight losses from leaves that had partly decomposed on land increased sharply when they were placed in the stream 9 months after abscission, showing that allochthonous material may influence stream chemistry by inputs throughout the entire year. The losses of weight and Ca from the leaves did not differ significantly at the 0.05 probability level in either environment; this suggests that the estimate of weight loss from decomposing deciduous leaves may also serve as an adequate index of the rate of Ca release. [Cf. F.A. 32 No. 85.KEYWORDS: Acer rubrum litter/humus \ Liriodendron tulipifera litter/humus \ forest litter \ forest litter \ decomposition rate \ Quercus alba litter/humus \ Soil chemistry Ca