Seasonal Dynamics of Leaf Litter Breakdown in a Utah Alpine Stream

Publication Title

Journal of the North American Benthological Society

Publication Date


Document Type





allochthonous, leaf litter, leaf breakdown, decomposition, community respiration




Seasonal breakdown patterns of leaf litter were studied in a Utah Rocky Mountain stream using box elder (Acer negundo) leaf packs between January 1976 and January 1977. Sets of 14, 5-g leaf packs were placed at two sites 400 m apart during the first week of each month. Two packs from each site were removed at 100-degree-day intervals. Leaf pack mass loss and community respiration rates were measured for each removal. Breakdown rates were fit to a negative exponential model using either days or degree days. For both days or degree days breakdown rate varied seasonally at each site and between sites. The fastest breakdown rates using days were in packs placed at the upper site in spring and summer and at the lower site in spring, summer and fall. Using degree days in the model, which factors out the temperature effect, the fastest breakdown rates at the upper site were in packs placed in July and in the following October-January period. At the lower site the fastest rates using degree days were in packs placed in July, late fall, and early winter. Highest respiration rates (mg O2/hr/g dry mass) were obtained for the June placement at the upper site and for the September placement at the lower site. These differences are probably due to differences in physical and biological conditions at the two sites.