It generally takes less time to re-establish dwarf shrub or shrub communities than
it does for a forest to grow old. This fact can also be seen as an opportunity,
especially if rare or threatened species can live in both shrubland and forest.
Keywords Heathland · Savanna · Shrubland · Threats to biodiversity · Future
perspectives
1 Introduction: Classification and Terminology
Heathland and shrub habitats include all ecosystems dominated by shrubs and small
trees (Davies et al. 2004; Specht 1979a). The maximum height of the vegetation is
usually defined as 5 m. The vegetation carpet is open, and many grasses, herbs and
mosses can be found. In many regions, such habitats are influenced to a greater or
lesser degree by anthropogenic activity. Heathlands and shrubs are often successional stages and can develop e.g. from forests and woodlands or grassland
(Hobohm 2014). Under environmental conditions which are not favourable for the
growth of trees this habitat type can also occur naturally and remain for long periods
of time in the same place.
Heathlands are characterized by short perennial ericoid plants on nutrient-poor
soils (Specht 1979a, b).
The term scrub comprises different ecosystem types, all of which are
characterised by the presence of small, woody perennial plants (Weber 2008). A
number of terms such as savanna, heathland, shrubland or others are used in different
parts of the world to describe these types of ecosystems; many of these terms are not
explicitly distinct from one another and can be used for the same entity. Table 1
gives some definitions or descriptions as used in the literature.
Compared to other habitat types such as forest or freshwater ecosystems, heath
and scrub have only fairly recently become a central theme of ecological and
biogeographical research, and have only been the subject of comparatively few
studies to date. Furthermore, the area covered by these habitats is only small
compared to that covered by forest and grassland. Although not well studied, and
despite the small area they cover, these habitats are very rich in species and
endemics.
The structure of savanna ecosystems is characterised by a combination of single
trees or groups of woody plants together with more open land dominated by grasses
and herbs. Such ecosystems are found in particular in tropical and subtropical zones.
Savannas occupy one fifth of the global land surface (Sankaran et al. 2010). Africa
has the most well known savanna, but savannas also exist in South America,
Southeast Asia and Australia (Pfadenhauer and Klötzli 2013), and often represent
a transition zone between woodland and grassland. One common characteristic of
savannas under the otherwise different climatic conditions is the seasonal rainfall
(Solbrig et al. 1996). The term savanna originates from a native American language
(Marchant 2010) and designates a landscape that can harbour a variety of
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N. El Balti
it does for a forest to grow old. This fact can also be seen as an opportunity,
especially if rare or threatened species can live in both shrubland and forest.
Keywords Heathland · Savanna · Shrubland · Threats to biodiversity · Future
perspectives
1 Introduction: Classification and Terminology
Heathland and shrub habitats include all ecosystems dominated by shrubs and small
trees (Davies et al. 2004; Specht 1979a). The maximum height of the vegetation is
usually defined as 5 m. The vegetation carpet is open, and many grasses, herbs and
mosses can be found. In many regions, such habitats are influenced to a greater or
lesser degree by anthropogenic activity. Heathlands and shrubs are often successional stages and can develop e.g. from forests and woodlands or grassland
(Hobohm 2014). Under environmental conditions which are not favourable for the
growth of trees this habitat type can also occur naturally and remain for long periods
of time in the same place.
Heathlands are characterized by short perennial ericoid plants on nutrient-poor
soils (Specht 1979a, b).
The term scrub comprises different ecosystem types, all of which are
characterised by the presence of small, woody perennial plants (Weber 2008). A
number of terms such as savanna, heathland, shrubland or others are used in different
parts of the world to describe these types of ecosystems; many of these terms are not
explicitly distinct from one another and can be used for the same entity. Table 1
gives some definitions or descriptions as used in the literature.
Compared to other habitat types such as forest or freshwater ecosystems, heath
and scrub have only fairly recently become a central theme of ecological and
biogeographical research, and have only been the subject of comparatively few
studies to date. Furthermore, the area covered by these habitats is only small
compared to that covered by forest and grassland. Although not well studied, and
despite the small area they cover, these habitats are very rich in species and
endemics.
The structure of savanna ecosystems is characterised by a combination of single
trees or groups of woody plants together with more open land dominated by grasses
and herbs. Such ecosystems are found in particular in tropical and subtropical zones.
Savannas occupy one fifth of the global land surface (Sankaran et al. 2010). Africa
has the most well known savanna, but savannas also exist in South America,
Southeast Asia and Australia (Pfadenhauer and Klötzli 2013), and often represent
a transition zone between woodland and grassland. One common characteristic of
savannas under the otherwise different climatic conditions is the seasonal rainfall
(Solbrig et al. 1996). The term savanna originates from a native American language
(Marchant 2010) and designates a landscape that can harbour a variety of
362
N. El Balti