Alpine food webs do not principally differ from lowland food webs. Nevertheless, there are some points to consider:

Alpine food webs are relatively poor in species. This has two main reasons: First, species diversity generally decreases with altitude and second, large parts of the alpine landscape are steppe habitats, which are generally species poorer than for example forest ecotones. Steppes contain fewer species because of their uniformity. They are less mosaic than forests but the phytomass productivity is much higher. Especially in spring, when lots of water is available through snow melt, the productivity of alpine steppes is enormous. Even though species diversity is low in alpine steppes, the density of organisms is high and exceeds that of forests.

1 - Food web of an alpine grassland

Unlike the common food webs of alpine steppes, that do not differ very much from lowland food webs, we can find a more specific food web in the sparse habitats of boulder fields, rocks and snow fields. Phytomass there is very low and food webs are not self-contained. Primary consumers are scarce (due to the lack of plants) and predators depend on external food entry. Nevertheless, a high diversity of predators exists in these areas and their food consists mainly of windblown invertebrates from lower altitudes.

2 - Food web of an alpine boulderfield

Characteristic for food webs depending on external entry is that they are less predictable and less robust than other food webs. External entry depends on many factors such as wind, weather and season. Food chains within the web are generally short and sometimes incomplete.

29 August 2011
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