Alterations of the Littoral Landscape

With reclamation and settlement at lake shores and along river corridors, the landscape is greatly altered by man. This leads to the decline of specific habitats and the typical species that inhabit these. For example, open marshland declines with increasing population density and recreative visitor frequency across the Netherlands (Figure 1), leading to declines in characteristic and red-list angiosperm plants and changes in bird communities. Lake fish communities adjacent to human development had fewer species and lower abundance than pristine sites, and were also characterized by a more disturbance-tolerant species assemblage. Along North American lake shores, the density of woody debris fragments in the littoral zone

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Figure 1 (a) covariation of recreative visitor density and population density in 21 wetland complexes across the Netherlands; (b) percentage of open marshland (fens, reedbeds) remaining in the wetland complex versus population density. In a multivariate analysis, angiosperm plant diversity declined in parallel with the percentage marshland, and characteristic reed bed bird species declined overall during the period 1965-1995. The filled symbol in (a) is excluded from the regression because in this wetland complex visitor entry is strictly regulated (the Naardermeer). Data re-analysed from Vermaat JE, Omtzigt N, and Goosen H (2007) A multivariate analysis of biodiversity patterns in Dutch wetland marsh areas: urbanisation, eutrophication or fragmentation? Biodiversity Conservation 16: 3585-3595.

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Adjacent human population density (km-2)

Figure 1 (a) covariation of recreative visitor density and population density in 21 wetland complexes across the Netherlands; (b) percentage of open marshland (fens, reedbeds) remaining in the wetland complex versus population density. In a multivariate analysis, angiosperm plant diversity declined in parallel with the percentage marshland, and characteristic reed bed bird species declined overall during the period 1965-1995. The filled symbol in (a) is excluded from the regression because in this wetland complex visitor entry is strictly regulated (the Naardermeer). Data re-analysed from Vermaat JE, Omtzigt N, and Goosen H (2007) A multivariate analysis of biodiversity patterns in Dutch wetland marsh areas: urbanisation, eutrophication or fragmentation? Biodiversity Conservation 16: 3585-3595.

declined precipitously with increasing cottage density, thus altering the inshore habitat and affecting benthic macroinvertebrate communities. In the Great Lakes area of North America, the high biodiversity and large numbers of ecologically and economically important fish associated with wetlands are a key reason to conserve and restore these habitats. Equally, river floodplains will be affected, when the main channel is straightened, parts of the floodplain will be cut off by dams and side arms and backwaters will be drained and reclaimed. In a comparative study across the United States, it was found that the protection of sites sought after by real-estate developing agencies would greatly help biodiversity conservation because of the large number of characteristic, but endangered species associated notably with shorelines. In short, large changes in habitat prevalence will affect presence and abundance of species with potentially unforeseen changes in ecosystem services provided.

During the last decade of the twentieth century, however, a trend reversal in awareness and management practices can be observed. Increasing attention is given to the amelioration and restoration of riparian habitat, including the protection of river banks from boat traffic-induced erosion, the (re-)creation of shallow wetland fringes and fish spawning habitat as well as passageways, and the (re-)opening of formerly straightened meanders.

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