Strand, Mary Ann. 1974. Canopy food chain in a coniferous forest watershed. In: Integrated research in the coniferous forest biome. Coniferous For. Biome Bull. 5. Seattle, WA: University of Washington: 41-47.
The internal structure and external couplings of the canopy food chainare examined to quantify the pattern of energy distribution in an old-growth Douglas-fir watershed. The food chain has been divided into ninefunctional groups: grazing vertebrates, grazing insects, sucking insects,seed and cone insects, predaceous birds, parasitic invertebrates, pre-daceous invertebrates, omnivorous birds, and nest predators. Surveys ofthe watershed fauna have shown that these functional groups are complexand may contain large numbers of species. For example, the five inverte-brate groups may include as many as 450 species.
Modeling techniques are employed to compute total annual consumption andsecondary production for two functional groups, grazing insects and omniv-orous birds. The estimates are based on field density records, publisheddata, and simplifying assumptions. The annual consumption by grazinginsects on the watershed is estimated to be 42.5 kg/ha or about 1.6% oftotal primary production. The omnivorous bird population consumes6.2 kg/ha while on the watershed; about 75% of their diet consists ofinsects. The consumption rates and mean standing crop values are similarto those reported for other forests. At current population levels, thisfood chain represents only a minor pathway in the total watershed energyflux.
INTRODUCTION