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We excluded litter (leaves and wood) inputs to an Appalachian headwater stream for 5 years. Leaves disappeared from the streambed very rapidly (< 1 year) following litter exclusion, however, a large residual mass of woody debris remained. After excluding inputs of leaf litter and wood to the stream for 3 years we removed all small wood (< 10 cm diameter) from the stream. There was close agreement (within 10%) between estimates of mass of small woody debris made using line intersect methods and that made by direct removal. Two years later, we removed all large woody debris (LWD = >10 cm diameter) from the wetted perimeter of the stream. Five annual estimates of LWD mass made with line intersect methods exceeded those of complete removal by a factor of about 2×, although total wood removed was within the 95% confidence interval of that estimated by the line intersect method. Species of wood removed from the stream displayed weak similarity (percent similarity = 45 to 49%) with recent (1993 and 1972) measures of basal area of tree species in the surrounding forest, but stronger similarity (65%) with tree species measured in 1934. About 37% of the LWD removed consisted of American chestnut, Castanea dentata, (∼24%) and black locust, Robinia pseudoacacia, (∼14%), which currently represent < 1.5% of the basal area of the surrounding forest. LWD in the stream reflects large inputs of chestnut following the chestnut blight in the1930s and inputs of early successional species such as black locust following extensive timber harvesting in the early 1920s. These earlier disturbances to the forest were important sources of LWD that remain in the stream today. Thus, the structure and function of present day streams are influenced by forest disturbances that occurred over six decades ago.

We examined the effects of resource limitation on stream invertebrate drift by reducing inputs of terrestrial detritus to a headwater stream in western North Carolina. In the treatment stream, leaf-litter was excluded for 6 years (September 1993 – August 1999), small woody debris was removed for 2 years (September 1996 – August 1998), and large and small woody debris was removed for 1 year (September 1998 – August 1999). Invertebrate abundance in the drift was significantly lower in the treatment stream during the study, but total biomass of invertebrate drift was similar. Although drift densities were higher in the reference stream, a greater proportion of total benthic invertebrate abundance and biomass drifted out of the treatment stream. The proportion of shredder, gatherer, and predator benthic abundance in the drift was significantly greater in the treatment stream, but scraper proportions were higher in the reference stream and filterer proportions were similar for the two streams. Combined data from both streams indicated that the relationship between drift densities and benthic abundance was positive and significant. Our results demonstrate that bottom-up effects of resource reduction in a detrital-based stream influence invertebrate drift, increasing the proportion of the benthic community emigrating from the detritus-poor stream.

1. Macroinvertebrate colonization dynamics were examined on artificial substrata in a stream with terrestrial litter inputs excluded, downstream of the litter‐exclusion treatment, and in a reference stream. 
2. Short‐term examination of the rates of organic matter accrual and invertebrate colonization demonstrated significantly lower accumulation of leaf detritus and invertebrates in the litter‐excluded reach and a short distance downstream of that reach. 
3. All major fractions of organic matter and invertebrates declined on artificial substrata during the 3‐year litter exclusion. Further, secondary production on artificial substrata in the litter‐excluded reach decreased from 6.2 to 1.5 g AFDM m−2 year−1 from pretreatment to the third year of litter exclusion, respectively. 
4. Downstream, fine particulate organic matter on artificial substrata decreased during litter exclusion, and there was a significant reduction in colonization of collector‐filterers. Total secondary production downstream of the litter exclusion declined >70%, demonstrating that downstream colonization dynamics are linked to upstream detritus inputs and processing by stream invertebrates.