The genetic component of biodiversity in forest ecosystems

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1 The genetic component of biodiversity in forest ecosystems Aristotelis C. Papageorgiou 1 and Dimitrios Kasimiadis 2 Department of Forestry, Environment and Natural Resources, Democritus University of Thrace, P.O. Box 129, Pantazidou 193, GR-68200, Orestiada, Greece. (1) apapage@fmenr.duth.gr, (2) dkasimia@fmenr.duth.gr Introduction The term biological diversity or biodiversity is broadly used and can be found in various environmental and development policy texts, such as international conventions, reports of world summits, global and regional environmental action plans. Furthermore, biodiversity has become an important concept of conservation biology and other theoretical and applied sciences, such as forestry, agriculture and wildlife biology. HAILA and KOUKI (1994) report of a rapid increase in the numbers of publications applying the term biodiversity over the period The first definitions of biodiversity (biological diversity or biotic diversity) were presented by the U.S. OFFICE OF TECHNOLOGICAL ASSESSMENT (1987), IUCN, UNEP and WWF (1991) and the Convention on Biological Diversity (CBD), during the 1992 Earth Summit in Rio 1. After reviewing these definitions, one could have the impression that a reasonable consensus exists on the meaning of the term biodiversity, including mainly two elements (PERLMAN and ADELSON 1997): biodiversity is viewed in three different levels, thus genes, species and ecosystems; biodiversity is used to describe the number, variety and variability of living organisms, embracing many different parameters, and becomes essentially a synonym of life on earth (see figure 1). These definitions seem to be simple and easy to be understood by various stakeholders and decision makers, who design and implement strategies for the conservation of biodiversity. However, after the first attempts to apply conservation strategies on the ground, we realize that such definitions turn out to be of limited use in practice. Several conceptual problems concerning the boundaries between taxonomical entities, the parallel reference of different hierarchical levels and the over-simplified bias of considering species richness as the main measure of biodiversity are the main reasons for the failure of the early definition of biodiversity as a concept for both scientific research and environmental policy (PERLMAN and ADELSON 1997; GASTON 1996 a ). Most conservation strategies at all levels include three main steps of action (i.e. IUCN, UNEP and WWF, 1991): An assessment of biodiversity, the choice of the conservation object and the methodology to be used and finally the implementation of the measures decided. Due to our inability to measure biodiversity, most attempts are still at the first stage (GASTON 1996 b ). It is evident, that a new approach of biodiversity, other than the one of a measurable entity, needs to be adopted. There seems to be a consensus on the importance in maintaining the integrity and functions of ecosystems. This means that biodiversity conservation strategies should focus more on the dynamic character of nature than on the endless count and maintenance of biotic entities (WESTERN 1992). 1 A detailed review of the most important definitions of the term biodiversity and their conceptual implications in conservation are presented by PERLMAN and ADELSON (1997).

2 The genetic component of biodiversity While most definitions of biodiversity refer to three levels including ecosystems, species and genes, the latter one is usually not included in conservation strategies and other environmental policy texts. We rarely see a conservation plan that focuses on genes as the primary element for protection (PERLMAN and ADELSON 1997). Several authors mention that genes are too difficult to assess and therefore cannot become the basic unit of biodiversity (i.e. DOBSON 1995), although the significance of genetic diversity within species is recognised (UNEP 1995). There are two different meanings of genetic diversity found in the biodiversity literature; a) specific genes that should be protected for their value for humanity (i.e. the wild relatives of crop plants, that are resistant to certain disease) and b) the genetic diversity itself, which should be considered for its importance against inbreeding and the accumulation of lethal recessive alleles in populations (PERLMAN and ADELSON 1997). The first approach is seen from a human point of view and refers to specific entities that are needed for primary production. Such elements are necessary for breeding of agricultural and forest plants and can be dealt with gene banks and other similar static measures. The second approach is closer to the genetic diversity of wild populations of species, but is missing the adaptability aspect; the fact that genetic diversity is the most important prerequisite for evolution of all species. PERLMAN and ADELSON (1997) claim that measurements of genetic diversity are summary statistics within a subdiscipline of population genetics and do not have any connection with the real world. It is evident that several authors consider the conservation of the genetic component of biodiversity either impractical (i.e. DOBSON 1995) or meaningless (i.e. PERLMAN and ADELSON 1997). The mistakes these authors do can be summarized in two points: a) they believe that an assessment of genetic diversity is needed prior the planning of any gene conservation measure; b) they consider the alleles and genotypes identified in the laboratories as the targets of gene conservation. It is true that if the above-mentioned points are valid, no actual conservation measure for genetic diversity has a meaning. It is well known to the genetic scientific community, that the genetic diversity found in the laboratories refer to gene markers, thus genes, the phenotypes of which are strongly connected with their phenotypes. Most, of these genes are irrelevant with the so-called adaptive genes and play a rather non-significant role for the survival of a population or a species. For this reason, the effort to conserve a certain rare allele at a marker gene locus is meaningless. Furthermore, even if this would have a meaning, the assessment of all possible genes of all populations of a species is technically impossible. The conservation of genetic diversity should aim at the maintenance of the adaptability of populations and not at the maintenance of a specific status quo (GREGORIUS 1991; ZIEHE et al. 1989). The task of gene conservation has a dynamic and not a static character. We are interested in having the species evolve, adapt and change. We do not wish to keep nature in a museum and for this reason we cannot consider conserving the genetic variants rather than the genetic diversity. Furthermore, genetic studies are not the aim of conservation, but a tool to conserve genetic diversity. Genetic studies often reveille the evolutionary history of populations and their capability for adaptation under new environmental conditions (FINKELDEY 1993; PAPAGEORGIOU 1997). They further indicate the effects of specific human activities on the genetic diversity and can lead us to improvements of our techniques to

3 manage nature and its resources. For these reasons, the consideration of the genetic component of biodiversity is of crucial importance for both, the development of conservation biological concepts and the planning of conservation strategies. Management techniques that will prevent disturbances in critical ecological and genetic processes need to be developed. A new concept is needed. Biodiversity research should not become a fragmented assessment of genetics, ecology and wildlife biology, based mainly on endless assessments. It should focus on the understanding of the main processes that keep biodiversity alive and allow evolution in space and time. Instead of trying to assess all possible genetic variants, genetic research should go on performing research and providing information on (BOSHIER and YOUNG 2000): the incorporation of genetic criteria into more general management procedures, the extrapolation of appropriate strategies for most taxa from the results of studies of a few model cases, the identification of the genetic aspects that may become limiting for certain species types and the monitoring and evaluation of demographic processes. Besides the targeted conservation of specific resources and units, biodiversity principles of all levels should be integrated into management techniques. Furthermore, biodiversity knowledge and understanding should be included in the principles needed for the planning of all nature related human activities. The challenge is to create space for all possible approaches on biodiversity that exist in our society. The genetic component of biodiversity in forest management Conservation of forest ecosystems has gained a significant part of conventions, treaties and action plans for biodiversity conservation. One major reason is the fact that forests are in many parts of the world the most wild, impressive and complex terrestrial ecosystems. Another reason could be the knowledge that forests are decreasing worldwide. Yet, the most important reason is probably the fact that forest science is the most developed applied on the ground nature management scientific discipline. Following the arguments presented in the previous chapter, the conservation of forest genetic diversity cannot be seen separately from the general use and management of forest resources. Each country and each region can have different approaches on the subject. The same happens with different parties of interest as well (sectors). Any forest genetic conservation effort should recognise these differences and adjust the measures designed with them. Taking the available information in account, management techniques should be developed, aiming at the optimisation of achieving multiple targets. The preservation of genetic diversity and the evolutionary adaptability of forest species should be included in these targets, in order to secure the long term functioning of forest ecosystems and the production of goods and services for society. This management-based approach of biodiversity and genetic diversity conservation is more likely to become effective, since it can reconcile the targets of forest management for production and biodiversity conservation (Figure 2). Sustainable forest management can be organized, based on the need to secure the long-term persistence of forest ecosystems (PAPAGEORGIOU et al. 2003). As a result, multiple targets can be achieved.

4 Acknowledgements The ideas developed in this article were greatly influenced from discussions with HANS H. HATTEMER, especially during his course Conservation of Mediterranean Plant Diversity at the Mediterranean Agronomic Institute of Chania. His teaching was a significant inspiration that has shaped our ideas and understanding on nature dynamics and biodiversity conservation. Literature Boshier, D.H., and Young, A.G., Forest conservation genetics: Limitations and future directions. In: Forest Conservation Genetics: Principles and Practices (Young, A., Boshier, D, and Boyle, T., eds), CSIRO Publishing, Australia. Dobson, A.P., Conservation and Biodiversity. Scientific American Library, New York, U.S.A. Finkeldey, R., Die Bedeutung allelischer Profile für die Konservierung genetischer Ressourcen bei Waldbäumen. Göttinger Forstgenetische Berichte 14, Gaston, K.J., 1996(a). What is biodiversity? In: Biodiversity: A Biology in Numbers and Difference (Gaston, K.J., ed), Blackwell Science, Oxford, U.K. Gaston, K.J., 1996(b). Species richness: Measure and measurement. In: Biodiversity: A Biology in Numbers and Difference (Gaston, K.J., ed), Blackwell Science, Oxford, U.K. Gregorius, H.-R., Gene conservation and the preservation of adaptability. In: Species Conservation: A Population Biological Approach (Seitz, A., and Loeschke, V., eds), Birkhäuser verlag, Basel, Switzerland. Haila, Y, and Kouki, J., The phenomenon of biodiversity in conservation biology. Ann. Zool. Fennici 31, IUCN, UNEP and WWF, Caring for the Earth: A Strategy for Sustainable Living. IUCN, Gland, Switzerland. Papageorgiou, A.C., Genetic structure of Mediterranean tree species as influenced by human activities. IUFRO Information Bulletin for Developing Countries, Summer 1997, Papageorgiou, A.C., Arabatzis, G., and Tampakis, S., Forest Development and Biodiversity in the Enlarged European Union. In: Hellas 2003: Events and Activities in the Forest Sector. CD-ROM, Hellenic Ministry of Agriculture, Greece. Perlman, D.L., and Adelson, G., Biodiversity: Exploring Values and Priorities in Conservation. Blackwell Science, Malden, Massachusetts, U.S.A. United Nations Environmental Programme (UNEP), Global Biodiversity Assessment. Cambridge University Press, Cambridge, U.K.

5 U.S. Office of Technological Assessment, Technologies to Maintain Biological Diversity. United States Government Printing Office, Washington D.C., U.S.A. Western, D., The biodiversity crisis: A challenge for biology. Oikos 63, Ziehe, M., Gregorius, H.-R., Glock, H., Hattemer, H.H., and Herzog, S., Gene resources and gene conservation in forest trees: General concepts. In: Genetic Effects of Air Pollutants in Forest Tree Populations (Scholz, F., Gregorius, H.-R., and Rudin, D., eds), Springer, Berlin Heidelberg, Germany.

6 Figure 1: Elements of biodiversity. This term is defined as a synonym of life on earth and can be categorized in several levels, from alleles to the biosphere. However, most definitions list ecosystems, species and genes (Perlman and Adelson 1997: p.9)

7 Figure 2: Sustainable forest management (SFM) focuses on the maintenance of forest biodiversity and secures the adaptability of forest ecosystems in the future. This reconciles the targets of timber production, the conservation of specific elements of biodiversity (i.e. wildlife species) and the provision of various social and environmental benefits (Papageorgiou 2003).