The protection of relict species is a prominent goal in nature conservation (Soule 1986; As et al. 1992). These are taxa with only small recent occurrences and which now show only isolated distribution remaining from a once wider distribution.
Institute of Forest Botany and Forest Zoology, TU Dresden, Tharandt, Germany e-mail: marcozi[email protected]
M. Vischer-Leopold, G. Ellwanger, A. Ssymank and E. Schröder
Department I 2.2 "Habitats Directive/Natura 2000", German Federal Agency for Nature
J.C. Habel and T. Assmann (eds.), Relict Species: Phylogeography and Conservation Biology, 323 DOI 10.1007/978-3-540-92160-8_19, © Springer-Verlag Berlin Heidelberg 2010
There may be very different reasons for their decline in the past. The species may be a relict of former stages of historical vegetation and landscape development resulting from past climate changes (glacial and post-glacial periods). Very often, the anthropogenic effects of cultural landscape development interfere or overlap with this, resulting in additional reduction of the distribution area, the density or fragmentation of patches or the population itself.
The scope of this paper is to focus mainly on the first category of relict species (which have developed mainly as a result of natural changes in abiotic conditions), as anthropogenic fragmentation and isolation has accelerated in recent decades and is at least partly documented in Red Data Books.
Most present-day relict species were widely distributed during the last glacial period, when their ecological requirements were well fulfilled; relict species with this type of distribution pattern are called climatic relicts or glacial relicts (e.g. Cox and Moore 2006).Today, these species are not well adapted to the prevailing climate conditions and are thus often very rare and localized, with the result that their occurrences are generally well documented. A prominent example of such glacial relict species is the dwarf birch (Betula nana) in bogs and fens in Germany. After the last glacial period, conditions were good for B. nana because cold-steppe vegetation covered the entire Central European landscape. Temperature increase resulted in more and more suboptimal conditions for B. nana, because other herbs and trees were more competitive and better adapted to the new conditions. B. nana was able to survive only in regions with low temperatures and low nutrient input where competition was reduced. Most glacial relicts, both plants and animals, follow this general pattern (Varga 1977). Often these species show arctic-alpine or boreo-alpine distribution patterns and are nowadays widely distributed in Northern Europe and/or remain isolated in cold areas such as the highest mountain regions or peatlands.
Thermophilic relicts represent a second type of relict species. These are the relicts from once warmer times during the Atlantic period, when thermophilic species were well adapted to warm and dry conditions. During this time, these species were widely distributed, but they later became isolated and restricted to favourable habitats due to colder temperatures and an increase of rainfall. A good example of a thermophilic relict is the Heath Bush-cricket Gampsocleis glabra in heathland in Northern Germany. In warm and dry years, Mediterranean species were able to expand to the North. When climate changes resulted in lower temperatures, these species were able to survive only in exposed habitats where higher temperatures are usually reached more quickly. This is often the case in stony and dry biotopes like dunes or rocks on Southern slopes. Areas with thermophilic relicts may often be found in the rain shadow of mountain ranges.
The goal of nature conservation is to conserve all these different types of relict species in their natural habitats as a witness of the natural conditions and developments in the past. Often it is quite clear that these species are not able to expand their ranges because current conditions are bad for them. In these often small populations with no contact to neighbour populations, evolution means that speciation and adaptation occur. This makes such populations very interesting objects of evolutionary research.
We have a responsibility to protect these species and their isolated populations. It is an important policy target to conserve a species' entire gene pool (BMU 2007; BFN 2008; Gruttke et al. 2004). The German government pointed out in its national strategy for biological diversity (BMU 2007) that the entire gene pool of species and populations has to be conserved, e.g. populations with local adaptations to regional microclimatic conditions. Fragmented populations often show significant changes in their character states, so if populations are separated for a long period from each other (several 1,000 years) with an interruption of gene flow, gene drift can mean that these populations change character states. The concept of Evolutionary Significant Units (ESUs) takes into consideration that such populations are on their way to an evolutionary unit of their own, leading to a different taxonomic status (Moritz 1994). For Germany, Gruttke et al. (2004) give a summary of current knowledge on this modern field of conservation biology, where glacial relicts are an important topic.
Nature conservation often means nature management. This involves the question of how relict species can be best protected. Since 1992, there has been an established, important and modern concept in nature conservation: The implementation of the EC Habitats Directive. The main goal of this Directive is to establish a network of Sites of Community Importance (SCI) for species listed in Annex II of the Directive. In Germany there are three biogeographic regions: Atlantic, Continental and Alpine (for further details see Balzer et al. 2008).0ne hundred and thirty-three plant and animal species as well as 91 habitat types are listed in Annexes II and I of the Habitats Directive, respectively. In Germany, a total of 4,622 SCI have been integrated into the EU network of protected areas "Natura 2000" for these species and habitat types. SCIs in Germany cover a terrestrial area of 3,313,083 ha equalling 9.3% of the territory. No scientific analysis has been performed to date to determine whether relict species are represented in the Natura 2000 network of protected sites in Germany. The current work gives an overview of whether, how and to what extent relict species are conserved by the EC Habitats Directive.
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