Abstract. Three small streams located at Coweeta Hydrologic Laboratory, North Carolina, USA, on an old field watershed, a pine plantation watershed, and a hardwood forest watershed were investigated to determine effects of watershed perturbation on K and Ca dynamics in the stream ecosystems. Data collected included measurements of litterfall inputs, large particulate organic matter and benthic organism standing crops, large particulate organic matter and organism drift, and insect emergence. We used Cs to estimate detritivore ingestion and elimination rates of Ca and K, respectively.We found that watershed perturbations had altered stream inputs and caused accompanying changes in the stream fauna. Our results indicated that the perturbed streams had less efficient physical processing of allochthonous inputs, but greater biological utilization of inputs. The streams exhibited high resilience to perturbation with complete recovery limited by the recovery rate of allochthonous inputs.
This article introduces and summarizes the foundations of network environ analysis and describes four primary properties resulting from this research. These properties-dominance of indirect effects (Higashi and Patten 1986), network amplification (Patten and others 1990), network homogenization (Patten and others 1990), and network synergism (Patten 1991)-provide insight into the behavior of holistic network interactions. In short, amplification, homogenization, and indirect effects demonstrate the influence of the indirect flows in a system to show that energy or matter cycling allows flow to return to the same component many times and tend to become evenly distributed within the network. Synergism relates direct and indirect, qualitative relations to show that network organization is, on the whole, more mutualistic than is apparent from direct interactions alone. Using network analysis, objects can be studied as part of a connected system and the indirect effects can be identified and quantified. This is a fundamentally different way of investigating ecosystems, and it gives a quantitative foundation to the widely held perception of the interconnectedness of nature.
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