A Trophic Dynamic View of Ecosystem

Energy losses limit the number of trophic levels in ecosystems. We began chapter 18 with a partial and highly qualitative energy budget of a forest: sunlight shines down on the canopy of a forest-some is reflected, some is converted to heat energy, and some is absorbed by chlorophyll. the energy budgets of ecosystem reveal that with cach transfer or conversion of energy, some energy is lost. to verify that these losses have the potential to limit the number of trophic level in ecosystems, we need to quantity the flow of energy through ecosystem. One of the very first ecologist to quantify the flux of energy through ecosystems was Raymond Linderman.

A Trophic Dynamic View of Ecosystem

Raymond received his Ph. D., where his studies of the ecology of Cedar Bog Lake led him to a view of ecosystems far ehead of its time. Lindeman webt from Minnesota to Yale University, whwre his association with G. F. Hutchinson from 1941 to 1942, led to the publication of a revolutionary paper with the provocative title, “ The Trophic-Dynamic Aspect of Ecology”. In this paper, Lindman articulated a view of ecosystems centered on the flows of energy through ecosystems that remains influential to this day. Like Tansley before him, Lindaman pointed out the difficulty and artificiality of separating organism from their environment and promoted an ecosystem view of nature. Lindeman concluded that the ecosystem concept is fundamental to the study of trophic dynamics, which he defined as the transfer of energy from one part of an ecosystem to another.

Lindeman suggested grouping organism within an ecosystem into trophic levels: primary producers, primary consumers, secondary consumers, tertiary consumers and so forth. In this scheme, each trophic level feeds on the one immediately below it. Energy enters the ecosystem as primary producers engage in photosynthesis using solar energy to convert CO2 into biomass. As energy is transferred from one trophic level to another, energy is lost due to limited consumption and assimilation, respiration by consumers, and heat production. The percentage of energy in yhe biomass at a lower thropic level that is called ecological efficiency, which varies from about 5% to 20%. As a result, the quantity of energy in an ecosystem decrease with each successive thophic level, forming a pyramid-shape distribution of energy among trophic levels. Lindeman called these trophic pyramids “Eltonian pyramids”, since Charles Elton was the first to purpose that distribution of energy among trophic levels is shape like a pyramid.