Effects of tannins on the decomposition of Chinese tallow leaves by terrestrial and aquatic invertebrates

Abstract

The hypothesis of this study was that tannins from Chinese tallow leaves have a negative effect upon terrestrial and aquatic reducer organisms and thereby may affect the overall rate of tallow litter decomposition. Species diversity and population size of aquatic reducers was lower in forest than adjacent grassland ponds; litter bags showed no difference in weight loss between bags which excluded reducers and those which did not. Differences in physical factors between habitats did not explain the paucity of reducers although rainfall permitted emigration of grassland organisms to forest ponds, yielding a temporary decrease in diversity.Tannin concentration in ephemeral ponds was altered by rainfall but leaching from leaves and soil continuously maintained tannin in ponds. Laboratory experiments showed that tannin was not directly toxic but inhibition of feeding caused high mortality in Asellus militaris and Crangonyx shoemackerii.Population density and reproduction of the terrestrial reducer (Armadillidium vulgare) was asynchronous with autumn leaf fall. Ground, leached leaves were consumed at much greater rate in laboratory experiments than unground, unleached leaves; in addition, mortality from starvation on the latter was high. These results suggest tallow leaves are not utilized by reducers until tannins are leached and the physical structure altered by rainfall and/or microbial action. Aquatic reducers are relatively unimportant in processing autumn leaf fall due to continual tannin leaching into ephemeral ponds from surrounding soil. Physical and microbial condition of leaves and leaching of tannin preceed spring and summer utilization by terrestrial isopods.

Seedbank Potential of Chinese Tallow Tree (Triadica sebifera) in a Texas Bottomland Hardwood Forest

“…In the southeastern U.S., the onset of new growth begins in February and flower production lasts from March through May (Cameron and LaPoint, 1978). Fruit set begins in July with asynchronous maturity lasting from October to November (Godfrey, 1988).…”

Temporary forest pools: can we see the water for the trees?

“…In intermittent ponds, this may be followed, as nutrients circulate into the water column, by an increase in phytoplankton which may accelerate into blooms that, in eutrophic waters, may compromise subsequent periphyton production through reduced light penetration (Bro¨nmark and Hanson 1998). Light penetration that may inhibit feeding in some invertebrates, may also be affected by the release of tannins from leaves that have accumulated on the bed, especially in the autumn in temperate regions (Cameron and LaPoint 1978).…”

The aquatic processing of sclerophyllous and malacophyllous leaves on a Mediterranean island (Corsica) : spatial and temporal pattern

“…Hence, high concentrations of phenolics serve as a de terrent for invertebrates as well as for hyphomycetes and bacteria. This affects not only the initial stage of decomposition, which lasts from 1 (Cameron & Lapoint 1978) to 2 weeks (Suberkropp et al 1976) after incubation, but also later on the palatability of leaves, when the phenolics have not been extracted complete ly by stream water and form complexes with.proteins (Rosset et al 1982). In green, fresh holm-oak leaves measured phenolic concentrations of 13 % of drymass, while alder attained only 4.7 % of dry-mass (Gessner 1991).…”

“…This influence of leaf characteristics on community structure has become widely recognized (Cameron & Lapoint 1978, Bengtsson 1992 4) The macroinvertebrate communities are compo sed of different species; 5) Furthermore, each stream ecosystem has its own variability of properties, be it on the microclimatical or the biotope level. This results in a considerable withinstream variability of leaf breakdown dynamics, as has been demonstrated for temperate regions (Reice 1974, Rosset et al 1982, Mutch et al 1983).…”