The influence of different litter bag designs on the breakdown of leaf material in a small mountain stream

Abstract

Leaf breakdown of two riparian tree species, Cunonia capensis L. and Ilex mitis (L .) Radlk . was investigated in vitro at Window Stream, Table Mountain, using three different designs of litter bag . Breakdown of Cunonia and flex in coarse-mesh (5 mm) litter bags was very rapid (respectively 14 .79 and 13 .93 % loss d -' ), and was significantly greater than the loss of leaf material of 1 % d -1 for both species from fine-mesh bags (180 µm) . Differences recorded between fine-mesh and composite-mesh bags (180 ym mesh with 5 mm mesh top) represented macro-invertebrate ingestion, and at t = 28 d, amounted to 67 .57 % material loss in Cunonia and 62 .58 % in flex . The losses due to microbial activity and leaching, 31 .28% in Cunonia and 29 .17% in flex were not significantly different . Weight loss of Cunonia in coarse-mesh bags (14 .79% loss d -1 ) and in composite-mesh bags (13 .93% loss d -1 ) did not differ, but this was not the case for Ilex, where a significantly higher rate of loss in coarse-mesh bags (13 .93 % loss d -') than in composite-mesh bags (7 .69 % loss d -1 ) was observed . This difference was used to quantify fragmentation losses . It was concluded that future leaf breakdown experiments in mountain streams must take cognisance of differential fragmentation losses before inferences can be made as to both invertebrate feeding preferences and biological decomposition of leaves .

Effects of Water Removal on a Hawaiian Stream Ecosystem

“…There were no differences in decay rates when summer values were compared with those in the winter months (P ¼ 0:11). These rates were higher than most reported from temperate streams (Rounick and Winterbourn 1983, Stewart and Davies 1989, McArthur et al 1994, Webster et al 1995) but similar to rates reported from tropical streams (Davies et al 1995, Benstead 1996. The half-life of guava leaves in Wainiha may be as much as [60][61][62][63][64][65][66][67][68][69][70] days.…”

Organic matter breakdown and ecosystem metabolism: functional indicators for assessing river ecosystem health

“…However, these problems can be circumvented by using appropriate mesh sizes and relatively small leaf bags and by exposing leaf bags for relatively short periods of time (Boulton and Boon 1991). Coarse-mesh bags (0.5-1-cm aperture) allow colonization by leafeating macroinvertebrates, and, thus, conditions in coarse-mesh bags simulate natural leaf breakdown more closely than do conditions in fine-mesh bags (e.g., Chergui and Pattee 1988, Stewart and Davies 1989, Gonzalez et al 1998, Gessner and Chauvet 2002, Menendez et al 2003. Both coarse-and fine-mesh bags ( 1 mm) should be used (e.g., Gonzalez et al 1998, Menendez et al 2003, Pascoal et al 2003, if feasible, to permit assessment of the relative contributions of macroinvertebrates and microorganisms (fungi and bacteria) to leaf breakdown (Gessner and Chauvet 2002).…”

Decomposition of Avicennia marina (Forsk.) Vierh. Foliage under field and laboratory conditions in the backwaters of Karachi, Pakistan

“…Mangrove litter decay and re-mineralization builds up soil organic matter which is a critical biogeochemical process in this ecosystem Osunkoya 2000, Dick andStreever 2001). In mangrove litter production and decomposition is species specific and is governed by a number of climatic, physicochemical and biologial processes (Peterson and Cummins 1974, Howard and Howard 1979, Stewart and Davies 1989. Decomposition of litter is also affected by C : N ratio, initial nutrient levels and lignin (lignocellulose) content of litter (Pahalawattarachichi and Amarasinghe 1997).…”