Autochthonous and allochthonous production – species richness most popular ways to make money

All biotic communities depend on a supply of energy for most popular ways to make money their activities. In most terrestrial systems this is contributed in situ by most popular ways to make money the photosynthesis of green plants – this is autochthonous production. Exceptions exist, however, particularly where colonial animals deposit feces derived from food consumed most popular ways to make money at a distance from the colony (e.G. Bat colonies in caves, seabirds on coastland) – guano is an example of allochthonous organic matter (dead organic material formed outside the ecosystem).

In the open water. However, a substantial proportion of the organic matter in aquatic communities most popular ways to make money comes from allochthon-ous material that arrives in rivers, via groundwater or is blown in by the wind. The relative importance of the two autochthonous sources (littoral and planktonic) and the allochthonous source of organic material in an aquatic most popular ways to make money system depends on the dimensions of the body of water most popular ways to make money and the types of terrestrial community that deposit organic material most popular ways to make money into it.

A small stream running through a wooded catchment derives most most popular ways to make money of its energy input from litter shed by surrounding vegetation most popular ways to make money (figure 17.4). Shading from the trees prevents any significant growth of planktonic most popular ways to make money or attached algae or aquatic higher plants. As the stream widens further downstream, shading by trees is restricted to the margins and autochthonous most popular ways to make money primary production increases. Still further downstream, in deeper and more turbid waters, rooted higher plants contribute much less, and the role of the microscopic phytoplankton becomes more important. Where large river channels are characterized by a flood plain, with associated oxbow lakes, swamps and marshes, allochthonous dissolved and particulate organic may be carried to the most popular ways to make money river channel from its flood plain during episodes of flooding most popular ways to make money (junk et al., 1989; townsend 1996).

The sequence from small, shallow lakes to large, deep ones shares some of the characteristics of the river most popular ways to make money continuum just discussed (figure 17.5). A small lake is likely to derive quite a large most popular ways to make money proportion of its energy from the land because its periphery most popular ways to make money is large in relation to its area. Small lakes are also usually shallow, so internal littoral production is more important than that by most popular ways to make money phytoplankton. In contrast, a large, deep lake will derive only limited organic matter from outside most popular ways to make money (small periphery relative to lake surface area) and littoral production, limited to the shallow margins, may also be low. The organic inputs to the community may then be due most popular ways to make money almost entirely to photosynthesis by the phytoplankton.

Figure 17.3 seasonal development of maximum daily gross primary productivity (GPP) for deciduous and coniferous forests in temperate (europe and north america) and boreal locations (canada, scandinavia and iceland). The different symbols in each panel relate to different forests. Daily GPP is expressed as the percentage of the maximum most popular ways to make money achieved in each forest during 365 days of the year. (after falge et al., 2002.)

Figure 17.3 seasonal development of maximum daily gross primary productivity (GPP) for deciduous and coniferous forests in temperate (europe and north america) and boreal locations (canada, scandinavia and iceland). The different symbols in each panel relate to different forests. Daily GPP is expressed as the percentage of the maximum most popular ways to make money achieved in each forest during 365 days of the year. (after falge et al., 2002.)

Estuaries are often highly productive systems, receiving allochthonous material and a rich supply of nutrients from most popular ways to make money the rivers that feed them. The most important autochthonous contribution to their energy base varies. In large estuarine basins, with restricted interchange with the open ocean and with small most popular ways to make money marsh peripheries relative to basin area, phytoplankton tend to dominate. By contrast, seaweeds dominate in some open basins with extensive connections to most popular ways to make money the sea. In turn, continental shelf communities derive a proportion of their energy from most popular ways to make money terrestrial sources (particularly via estuaries) and their shallowness often provides for significant production by littoral most popular ways to make money seaweed communities. Indeed, some of the most productive systems of all are to most popular ways to make money be found among seaweed beds and reefs.

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