Energy Dynamics of a Food Chain of an Old‐Field Community

Abstract

In recent years there has been a growing interest in the study of the transfer of energy through natural systems (ecosystems, Tansley 1935). Park (1946) stated that probably the most important ultimate objective of ecology is an understanding of community structure and function from the viewpoint of its metabolism and energy relationships. Aquatic biologists have taken the initiative in the study of comillunity energetics, and most of the information available today concerns fresh water or marine communities. A great need exists for similar studies on terrestrial communities. In this study a food chain of the old field comnmunity, from perennial grasses and herbs to the meadow mouse, Microtus pennsylvanicus pennsylvanicus Ord, and to the least weasel, Mustela rixosa allegheniensis Rhoads, was chosen for investigation. This food chain included the dominant vertebrate of the conlinunity (Microtus) and one of its main predators (Mustela) but excluded the otherwise important insects, other invertebrates, bacteria, and fungi. The primary objectives of the study were to determine (1) the rate of synthesis of organic matter by the primary producers-the vegetation, (2) the path of this energy from the vegetation through the mouse to the weasel, and (3) the losses of energy at each step in the food chain. The writer wishes to acknowledge with gratitude the suggestions and guidance of Dr. Don W. Hayne, Institute of Fisheries Research, Michigan Department of Conservation, especially concerning that portion of the study dealing with the population dynamics and productivity of the Microtus population. The writer also thanks Dr. John E. Cantlon, Department of