2.1.1 Range of Habitat Groups
Also to date it is difficult to find reliable numbers for the global range of different
habitat types. Table 1 contains data of different sources, definitions and modes of
calculation. It shows the partitioning of the surface of the Earth with respect to large
groups of habitat types. However, these numbers serve as a first orientation because
it can not be guaranteed that different authors and sources have used the same
classification scheme.
The range of desert, arable land, urban and artificial habitats is currently increasing. The range of grassland, shrubland, glaciers, and active floodplains is decreasing
while the range of the deeper ocean, rocks and screes, and intertidal habitats is
remaining more or less constant. There is some discussion about the tendency of the
whole range of forest. However, this dispute relates to the use of deviating definitions of the term "forest". The area of forest clearly declines in large areas of S
America, notably in Brazil, and in tropical and subtropical regions of Africa and Asia
while the range in Europe is increasing. There is another discussion about the range
of coastal habitats in the face of rising sea level. However, we assume that the
quantity of coastal sediments during the last 30 years was slightly increasing
(Donchyts et al. 2016), and that typical habitats such as dunes and salt marshes are
decreasing because of anthropogenic damage and conversion.
Recent trends most probably will continue for the next years or decades. The
categories of habitat types are used as follows for further numerical analyses.
2.1.2 Marine Habitats
Marine habitats or ecosystems are water bodies and substrates directly connected
with the ocean. Marine waters are normally fully saline, exceptionally or in transition
zones brackish or almost fresh, like for example in the northern part of the Baltic Sea
with very low salt concentration.
The neritic parts are shallow waters of the shelf oceans between c. 200 m depth
and low tide (e.g. Fig. 1).
Marine ecosystems at high latitudes include bodies of swimming ice. Marine
benthic (related to soils) and marine pelagic (water bodies) ecosystems can be
distinguished.
The low tide level in this classification scheme roughly marks the border between
marine oceanic and marine intertidal ecosystems. Subtidal seagrass beds, for example with Zostera marina (ssp. marina) in the Baltic Sea are grouped within the
marine oceanic environment whereas seagrass beds with Zostera marina (ssp.
angustifolia) and Zostera nana living on tidal flats of the Wadden Sea area characterize the transition zone between sea and land and are part of the intertidal
ecosystems which here are grouped within the coastal and saline habitats.
Distribution and Habitat Affinity of Endemic and Threatened Species: Global and. . .
239
Also to date it is difficult to find reliable numbers for the global range of different
habitat types. Table 1 contains data of different sources, definitions and modes of
calculation. It shows the partitioning of the surface of the Earth with respect to large
groups of habitat types. However, these numbers serve as a first orientation because
it can not be guaranteed that different authors and sources have used the same
classification scheme.
The range of desert, arable land, urban and artificial habitats is currently increasing. The range of grassland, shrubland, glaciers, and active floodplains is decreasing
while the range of the deeper ocean, rocks and screes, and intertidal habitats is
remaining more or less constant. There is some discussion about the tendency of the
whole range of forest. However, this dispute relates to the use of deviating definitions of the term "forest". The area of forest clearly declines in large areas of S
America, notably in Brazil, and in tropical and subtropical regions of Africa and Asia
while the range in Europe is increasing. There is another discussion about the range
of coastal habitats in the face of rising sea level. However, we assume that the
quantity of coastal sediments during the last 30 years was slightly increasing
(Donchyts et al. 2016), and that typical habitats such as dunes and salt marshes are
decreasing because of anthropogenic damage and conversion.
Recent trends most probably will continue for the next years or decades. The
categories of habitat types are used as follows for further numerical analyses.
2.1.2 Marine Habitats
Marine habitats or ecosystems are water bodies and substrates directly connected
with the ocean. Marine waters are normally fully saline, exceptionally or in transition
zones brackish or almost fresh, like for example in the northern part of the Baltic Sea
with very low salt concentration.
The neritic parts are shallow waters of the shelf oceans between c. 200 m depth
and low tide (e.g. Fig. 1).
Marine ecosystems at high latitudes include bodies of swimming ice. Marine
benthic (related to soils) and marine pelagic (water bodies) ecosystems can be
distinguished.
The low tide level in this classification scheme roughly marks the border between
marine oceanic and marine intertidal ecosystems. Subtidal seagrass beds, for example with Zostera marina (ssp. marina) in the Baltic Sea are grouped within the
marine oceanic environment whereas seagrass beds with Zostera marina (ssp.
angustifolia) and Zostera nana living on tidal flats of the Wadden Sea area characterize the transition zone between sea and land and are part of the intertidal
ecosystems which here are grouped within the coastal and saline habitats.
Distribution and Habitat Affinity of Endemic and Threatened Species: Global and. . .
239