Jm. Rowe et al., COMPARISON OF LEAF PROCESSING RATES UNDER DIFFERENT TEMPERATURE REGIMES IN 3 HEADWATER STREAMS, Freshwater Biology, 36(2), 1996, pp. 277-288
1. We studied the effects of different temperature regimes on leaf lit
ter processing in three forested Appalachian headwater streams of diff
erent pH (mean pH = 4.2, 6.5, 7.5). 2. We compared leaf breakdown rate
s, microbial biomass and macroinvertebrate shredder density and biomas
s between two 12-week processing periods (October-January and November
-February) in each stream. Leaf processing rates were calculated both
as k (day(-1)) and k(d) (degree day(-1)). 3. There were no significant
differences in processing rates (k day(-1)) between the two study per
iods for any leaf species in any stream. The average difference in tem
perature between the two study periods was 175 degree days. Shredder d
ensity was significantly higher during the earlier study period on 40%
of the sample dates, but shredder biomass was not significantly diffe
rent between the two study periods. ATP concentration was significantl
y higher during the early study period for 60% of the sample dates. 4.
More significant differences in these variables (shredder density and
biomass, ATP concentration) were seen among the three study streams t
han between the two study periods. This indicates that in this study o
ther factors, particularly stream pH, contributed more to processing r
ate variation than did differences in thermal regime.