Food webs – Food webs represent energy flows within an ecosystem and provide a look into the connectedness of plants and animals within an ecosystem. The image below is an example of this type of visualization. Most often, webs are composed of different nodes: producers, consumers, detritivores, etc. Nodes are connected by arrows that represent their relationships to one another.
Why? Food webs are a way to better understand how, why, and where energy flows within a system. Fully understanding these connections can allow us to understand and prevent large scale decreases in ecosystem productivity and health.
Source: Gale Virtual Reference Library, Berkshire Encyclopedia of Sustainability
Productivity – Is the amount of energy plants can harvest per unit area per unit time. Gross primary productivity (GPP) measures the total energy harvested, which includes energy needed for plant respiration. Net primary productivity (NPP) measurements only take into account usable energy stored within the plant bodies. The energy measured by NPP is usually transferable through trophic levels. The map below shows the NPP of earth’s terrestrial ecosystems.
Why? When grown and harvested correctly, plants are an almost inexhaustible source of resources and energy. Measures of productivity allow us to gauge this potential.
Source: Gale Virtual Reference Library, Environmental Encyclopedia