Leaf litter decomposition and macroinvertebrate communities in headwater streams draining pine and hardwood catchments

Abstract

Benthic invertebrates, litter decomposition, and litterbag invertebrates were examined in streams draining pine monoculture and undisturbed hardwood catchments at the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains, USA. Bimonthly benthic samples were collected from a stream draining a pine catchment at Coweeta during 1992, and compared to previously collected (1989-1990) benthic data from a stream draining an adjacent hardwood catchment. Litter decomposition and litterbag invertebrates were examined by placing litterbags filled with pine or maple litter in streams draining pine catchments and hardwood catchments during 1992-1993 and 1993-1 994. Total benthic invertebrate abundance and biomass in the pine stream was ca. 57% and 74% that of the hardwood stream, respectively. Shredder biomass was also lower in the pine stream but, as a result of higher Larctra spp. abundance, shredder abundance was higher in the pine stream than the hardwood stream. Decomposition rates of both pine and red maple litter were significantly faster in pine streams than adjacent hardwood streams (p<0.05). Total shredder abundance, biomass, and production were similar in maple bags from pine and hardwood streams. However, trichopteran shredder abundance and biomass, and production of some trichopteran taxa such as Lepidostoma spp., were significantly higher in maple litterbags from pine streams than hardwood streams (p<0.05). In contrast, plecopteran shredders (mainly Tallaperla sp.) were more important in maple litterbags from hardwood streams. Shredders were well represented in pine litterbags from pine streams, but low shredder values were obtained from pine litterbags in hardwood streams. Results suggest conversion of hardwood forest to pine monoculture influences taxonomic composition of stream invertebrates and litter decomposition dynamics. Although the impact of this landscape-level disturbance on invertebrate shredder communities appeared somewhat subtle, significant differences in decomposition dynamics indicate vital ecosystem-level processes are altered in streams draining pine catchments.

Citation

Whiles, Matt R.; Wallace, J. Bruce. 1997. Leaf litter decomposition and macroinvertebrate communities in headwater streams draining pine and hardwood catchments. Hydrobiologia, Vol. 353: 107-119