Ecosystem Scales

FOREST ECOSYSTEM STRUCTURE AND ORGANIZATION (Chapter 1)

ECOSYSTEM: A complex association of biotic and abiotic factors that interact to perpetuate or sustain itself, Tanley (1935) introduced the term but the concept goes far back to early historical descriptions of vegetation types

Structure – the biotic and abiotic components and their interactions:

Fig. 1.3 and 1.4 demonstrate ways to consider ecosystem structure and the structural linkage between the organisms in an ecosystem and their environment. This is shown as a structure of interconnected parts that are exposed to the abiotic factors (environment) AND also provide feedback modification of the environment. For example, transpiration (water release by vegetation) humidifies the atmosphere. The combination of organisms, environment and interactions allows the ecosystem to function.

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Function – the processes that are preformed by the ecosystem – e.g. carbon (energy) balance and flux, decomposition, nutrient cycling, regeneration and succession, etc. e.g.

Fig 1.4 shows connections and feedback of all parts. This shows a structure and how it allows functions ff all parts – note all parts are related and interact. Tid-bit – “function” vs “functioning”

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So, in a little review – we often describe or categorize ecosystems (and thus study them) by the way they look or as geographic units.

1. PHYSIOGNOMY. Structure of the ecosystem – what does it look like?

A. Bioecosystem – e.g. forest types such as pine, oak, oak-hickory, etc. Emphasis may be on a single species (autecology)

B. Geoecosystem – a geographic unit, Landscape Ecosystems

e.g. desert, alpine, etc. This may include an entire unit of area that consists of a few to many communities and forest stand types – the study of the relationship between these is called LANDSCAPE ECOLOGY

LANDSCAPE: a heterogeneous land area composed of a group of interrelated and overlapping (layered) ecosystems...