Coarse Benthic Organic Matter

Abstract

Coarse particulate organic matter is the main energy source for consumers in forest streams. Although diverse, this source is dominated by leaves, whose quantity in the streambed is highly variable at both spatial and temporal scales. Disturbances in the riparian vegetation and stream channels further contribute to this variability. This chapter describes a method to estimate the amounts of coarse benthic organic matter (CBOM) stored in small streams. In a stream reach that is as representative as possible, all CBOM in five randomly selected transects is collected with a Surber-type sampler. The collected material is sorted into different categories such as leaves, twigs, bark, fruits, flowers and debris. All fractions are dried, weighed, ashed and reweighed to determine ash-free dry mass (AFDM) and results are expressed in terms of grams per square metre. Potential applications of this method include assessments of differences in CBOM among similar-sized streams experiencing different degrees of riparian disturbance, assessment of stream restoration measures or studies of stream food webs.