Bastian Landscape Ecology Towards A Unified Discipline

Landscape Ecology 16: 757–766, 2001. © 2002 Kluwer Academic Publishers. Printed in the Netherlands.

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Perspective paper

Landscape Ecology – towards a unified discipline? Olaf Bastian Saxon Academy of Sciences, Neustädter Markt 19 (Blockhaus), D-01097 Dresden, Germany (e-Mail: [email protected]) Received 6 December 1999; Revised 22 September 2000; Accepted 2 April 2001

Key words: complementarity, geographical and biological roots, holistic perspective, landscape evaluation, landscape visions, transdisciplinarity

Abstract Contemporary landscape ecology is not unified at all. There are historical, geographical and biological reasons for the lack of unification, as well as differences between science and application. The search for a unified theory of landscape ecology should consider previous concepts such as ‘landscape diagnosis’ and ‘landscape functions’ which were elaborated in Central Europe. Because of the various aspects in a landscape (components, processes, relations), landscape ecology should be regarded as a multidisciplinary, better a transdisciplinary, science where different views and approaches are involved in a holistic manner. The principle of complementarity is helpful to understand and describe the landscape. As a crucial step, the transformation of natural science categories to categories of the human society is brought out. This is realized by land(scape) evaluation and by the elaboration of goals (visions) of landscape development.

Introduction Landscape ecology today appears to be a wide spectrum of views, theories and methodologies. This heterogeneity results from different landscape conceptions (look at the still living question ‘What is a landscape?’), scientific backgrounds, and specializations. One example is the existence of a more (bio)ecologically focused approach which deals especially with habitat patterns, fragmentation and patch heterogeneity, connectivity and other aspects of population biology in contrast to another fundamental approach which has its roots in geography, and therefore includes abiotic parameters and whole geocomplexes in a comprehensive manner. Landscape ecology is still passing through a process of self-discovery. Hobbs (1994 in Wiens 1999) characterized landscape ecology as “a science in search of itself”, which was demonstrated at the 5th IALE-World Congress (International Association for Landscape Ecology) in Snowmass, Colorado, USA (29 July–3 August 1999). This self-discovery con-

tains, for example, the search for the unification of landscape ecology as a discipline (Wiens 1999b), the question “What is the most favourable – or even the right – view of landscape ecology?”, the relation between basic research and application (the science and the action) and between holistic and sectoral approaches and methodologies; and the improvement of scientific exchange to avoid ignoring results from non-anglophone countries. The situation was summed up by Moss (1999): “... landscape ecologists will have a clearer idea of the goals and the context for their work. Of equal importance, the non-landscape ecologist will have a much clearer idea of what landscape ecologists do and can do. In other words, the field needs a focus and a profile.” It is worth investigating if the demand for a unified discipline is realistic, and, if yes, how we can implement it, and which premises should be taken into consideration.

758 Different definitions Landscape Regarding the position, development and future of landscape ecology, we should remember the numerous existing definitions of the term ‘landscape ecology’ and its two roots: landscape and ecology. First, the scientific term ‘landscape’ was shaped by geographers, essentially by the German geographer and scholar Alexander von Humboldt 200 years ago (the landscape as the total character of a region). In 1850, Rosenkranz defined landscapes as hierarchically organized local systems of all the kingdoms of nature. Neef (1967) characterized landscape as a part of the earth’s surface with a uniform structure and functional pattern. Both appearance and components (geofactors: relief, soil, climate, water balance, flora, fauna, humans and their creations in the landscape), including their spatial position, are concerned. Landscape is not however, only the sum of single geofactors, but an integration forming the geographical complex (or geosystem). Thus, landscape is from different spheres: inorganic spheres, biosphere and sociosphere. According to Naveh (1987): “landscapes dealt with in their totality as physical, ecological and geographical entities, integrating all natural and human (caused) patterns and processes ...” or Forman and Godron (1986) defined “landscape as a heterogeneous land area composed of a cluster of interacting ecosystems that is repeated in similar form throughout”. Leser (1997) regards the landscape ecosystem as a spatial pattern of abiotic, biotic and anthropogenic components which form a functional entity and serve as human’s environment. Early definitions (19th and beginning 20th century) from Central and Eastern Europe, where the geographical and the biological roots of landscape ecology occur, reflect a holistic landscape conception. Later, influenced by the rising analytical natural sciences, the “core of an all-embracing thought pattern was not appreciated” (Lehmann 1986). Still today, we also can observe repeated tendencies of reduction and specification: landscapes consist of “structural components, or landscape elements, (which) are patches of several origins, corridors of four types, and a matrix” (Forman 1981) or “The (ideal) landscape is a primarily aesthetic phenomenon, closer to the eyes than to the mind, more related to the heart, the soul, the moods than to the intellect” (Hard 1970). We also find the rejection of the landscape paradigm, as King (1999) asks: “Is there in fact

a landscape level”, or if Widacki (1994) wants to turn away from geocomplexes because we could fall back now on “satellite images as well as the resulting possibilities of integration and transformation of data read into computer with the aid of GIS”. Generally we can realize, in view of the environmental problems coming to the fore that landscape is regarded more and more as a complex, highlyintegrated system. Landscape ecology The second part of the term landscape ecology – the science ecology – deals with the investigation of relations between life and its abiotic environment (E. Haeckel). The term landscape ecology was coined by the German biogeographer Carl Troll at the end of the 1930s. Interpreting an East-African savannah landscape with the help of aerial photographs, Troll was fascinated by the important scientific findings due to the functional, vertical approach of ecologists with the spatial, horizontal approach of geographers. But already earlier, A. Penck (1924) asked about the earth’s carrying capacity, and S. Passarge (1912) used the term landscape physiology (Finke 1994). Later, e.g., Schmithüsen, Neef, Haase, Richter, Barsch, Schreiber, Leser and others did important work in landscape ecology in Germany, and abroad. A similar development took place in Russia (e.g., Sukachev and Dylis 1964; Soˇcawa 1974) and other Eastern European countries. Since then there are at least two fundamental, different views on landscape ecology (corresponding to its ‘mother sciences’): – A more biological one, esp. in Northern America and some schools in Europe (e.g., Forman and Godron (1986). – A more geographical approach, esp. in Central and Eastern Europe (e.g., Neef 1967, Haase 1990, Richling 1994), but also in Latin America (Baume et al. 1994; Cervantes et al. 1999). This conception is often equated with geoecology, which is not completely correct. The term geoecology was introduced by Troll (1968) as a synonym to improve translatability, but it did not gain much acceptance. Especially in Germany (e.g., Neef and his pupils), geoecology embodies a division of landscape ecology dealing only with the abiotic issues (such as soils, water balance). Leser (1997) distinguishes geoecology, bioecology and the all-embracing landscape ecology (which also considers anthropogenic factors).

759 The differences concerning these terms represent only one part of the existing lack of clarity. Some definitions are both concise and comprehensive, e.g., Forman (1981): “... landscape ecology, thus, studies the structure, function and development of landscapes”; or Leser (1997): “Landscape ecology deals with the interrelations of all functional and visible factors representing the landscape ecosystem.” According to Forman and Godron (1986) there are “three fundamental characteristics of landscape ecology, ... the space relations – landscape structure, their functional relationships - interaction, flow of material and energy and the time relations – the change of the structure, characteristics and functions”. Other definitions reflect a narrow view, e.g.: “Landscape ecology is the study of spatial variation in landscapes at a variety of scales. It includes the biophysical and societal causes and consequences of landscape heterogeneity” (IALE Executive Committee, in Moss 1999). I’ll deepen this concern within the following section. Other authors emphasize both the chorological and the ecosystem aspects of landscape ecology, deriving from geographical and biological roots (Otahel 1999). Naveh and Lieberman (1984) base landscape ecology “on a general systems theory, biocybernetics, and ecosystemology” and emphasize the “active human role in landscape”. This last-mentioned definition corresponds to the absolutely welcome tendency to include human to landscape issues in an increasing manner. The relation between basic and applied research is a further contentious point. Some authors, e.g., Leser (1997), emphasize the importance of basic research (without ignoring practical application). Jongman (1999) wrote: “Landscape ecology is a field of science with perspectives for application. From the 1970s there has been a mutual relationship between landscape ecology and land-use planning and landscape management.” For other authors, a strong focus on application is characteristic: “Landscape ecology is applied may landscape planning oriented ecological research direction” (Haber 1979). It is “determined by its goal – environmental protection. It means that it is an environmental research field, i.e., the applied field of theoretically recognized disciplines” (Drdoš 1996). At the same time, there are somewhat dangerous tendencies to define landscape ecology too widely, i.e., to subsume under the term ‘landscape ecology’ all appearances being related to landscape in a certain manner: Landscape ecology includes “perspectives as varied as theoretical ecology, human geography, land-

use planning, animal behaviour, sociology, resource management, photogrammetry and remote sensing, agricultural policy, restoration ecology, or environmental ethics” (Wiens and Moss 1999). For Miklós (1996) landscape ecology is “the science of the environment in the wide sense of the word.” But not all issues which are related to landscape are landscape ecology! Landscape ecology is a science. Landscape planning is a procedure. Landscape aesthetics, perception, decision making are not ecology! Landscape ecology itself cannot act! Remote sensing, GIS, spatial statistics, and models, are tools. Landscapes have properties that go beyond science. “Landscape ecology cannot explain all the processes, but can undoubtedly help us to understand the complexity ...” (Farina 1998). There is a real danger that the term landscape ecology may become wishy-washy like terms as ecological equilibrium, ecological stability, ecological disaster, or sustainability. I agree with Moss (1999) that landscape ecology is not the only field which deals with the landscape and it certainly is not the all-embracing environmental science. It is, however, a field with the potential to make a unique contribution to solving a particular subset of natural-resource based issues. Pointing to this fact, however, I do not reject the necessity of a holistic approach in landscape ecology (see The holistic perspective section).

Partial aspects of landscape ecology As mentioned above, there are no identical conceptions of landscape ecology. Under the broad field of landscape ecology, various activities of basic research and application are realized. So it is no wonder that some authors or scientific schools emphasize particular issues, and that single aspects are brought out or examined out of context. On the one hand, the investigation of such single aspects can contribute to the knowledge of the whole landscape system; on the other hand, such specialized views can become independent, and the sight of the total system can be lost. Examples shall be discussed on the view of: – spatial relationships, and – single landscape components. Spatial relationships It is true that the spatial character of research in landscape ecology is very important. If landscape ecology

760 is defined as “the study of the structure and dynamics of spatial mosaics and their ecological causes and consequences” (Wiens 1999b), or “Landscape ecology deals with the spatially-explicit relationships among patch types in complex mosaics”, and “that nature is heterogeneous and scale matters, are in fact the raisons d’être of landscape ecology” (Wiens 1999a), or “The spatial dimension has been recognized as extremely important from a topological approach to one in which the real world is studied” (Farina 1998), it is obvious that spatial relations are very important indeed, but they are only one of the relevant foci. The question should be allowed, is only investigation of spatial patterns (e.g., of populations) landscape ecology? If yes, we could add to landscape ecology also other phenomena, if the existence of spatial aspects is sufficient for such a classification. “Much contemporary work on pattern has focused on the analysis or description of spatial geometry and has failed to provide any understanding of the significance or meaning of those patterns” remarked Haines-Young (1999). Li (1999) criticized that studies in landscape ecology “have been dominated by taking things apart and characterizing various attributes of spatial patterns. These studies generally do not address the intrinsic causality and underlying dynamics of the pattern”. To the contrary, “the object of landscape ecology is not only to describe landscapes, but to explain and understand the processes that occur within them. Thus the description of landscape pattern as an end in itself is limited. It is certainly misguided, given the need to find more sustainable forms of landscape management” (Haines-Young 1999). The limited meaning of simple patterns (such as woodlots and other habitat fragments) cannot be extended to the holistically defined geocomplexes (of the geographical approach) which are, in the end, patterns, too. “To justify the existence of landscape ecology merely as a spatial science is severely restrictive. Do not most environmental and other disciplines have a spatial dimension also?” (Moss 1999). According to Solon (1999), space may be understood in two ways: as an arena characterized solely by geometrical features, upon which abiotic and biotic processes (including the life histories of organisms) are played out, or in its entirety, together with its attributes, features and dynamics. “The goal (and the challenge) of landscape ecology, however, is to go beyond these simple statements to explore the richness of basic and applied problems” (Wiens 1999a).

The dominating biological view Absolutely, interesting and important landscape ecological approaches are based on population dynamics, e.g., patch-corridor-matrix models, greenways, connectivity, ecological infrastructure, habitat networks, ecological barriers, biocentres and biocorridors forming a skeleton of ecological quality and stability. In spite of all scientific and practical significance, we are dealing with partial aspects of a landscape, especially “with (bio)ecology in the landscape” (Moss 1999), though we should think about landscape systems as a whole. While distinguishing a human, a geobotanical and an animal perspective, Farina (1998) accents a dominating biological view. The occupation with “habitat patches in a landscape” or with “patch quality to the organisms occupying a landscape” (Wiens 1999a) indicates a strong biological conception, too. The numerous works about landscape fragmentation speak about the landscape admittedly, but they mean habitats (e.g., fragmentation of woods). According to Pietrzak (1998), a ‘hypertrophy’ of the biological approach is evident, i.e., the biological view is overstressed. The patch-corridor-matrix model (Forman 1981, Forman and Godron 1986) also belongs here, even if it was elaborated for matter and energy fluxes. This fact is not altered by the acceptance that this model has found, even in Europe: The model ...“is at present a widely accepted, efficient method of describing landscape structure and – as it seems – an optimum proposal of landscape research for planning and designing activities in landscape” (Pietrzak 1998). Regarding the widespread tendency of reducing landscape’s complexity to single aspects or components, Leser (oral comm.) marks it as “playing with names”. Moss (1994) draws attention to the “drift away from this broad integrative concept to a dominance of the field by community and ecosystem scientists whose perception of landscape ecology is that of spatial community ecology.” The risk that – in consequence of landscape ecology’s explosive growth – the “subdisciplines will seek their own identity and will look inward rather than outward, splintering rather than consolidating landscape ecology” is mentioned also by Wiens (1999b). Antrop (1999) identifies quite different approaches in landscape ecology: sectoral (e.g., forestry, nature conservation), integrated (e.g., spatial planning), compartments (e.g., biological), and themes (e.g., fragmentation).

761 Summarizing the cited intellectual positions, we can state that restricted views and foci are still usual in landscape ecology, despite the tendencies of spreading the holistic approach.

The holistic perspective Outstanding features of landscape ecology are – in my opinion – the focus on – structures, processes and changes, – spatial and hierarchical aspects, – the complexity of different factors in a landscape. The holistic approach in the context of humannature-relations is the real challenge of modern landscape ecology regarding the background of increasing environmental problems and the discussion about sustainability. In the last years, the consideration of both natural and social components has been given more and more attention: “The time is ripe for change; a holistic ... approach is needed. ... the ecological system cannot be understood by reducing it to its parts” (Li 1999). Especially, great value is attached to the human factors, since “it would be naive to conduct basic scientific investigations of those landscapes without considering the anthropogenic forces that have shaped them” (Wiens 1999b) and the “accelerated landscape change is an anthropogenic phenomenon”... which “demands a permanent and consequent consideration of the context: nature-technique-society” (Leser 1997). In other words: “A co-evolutionary relationship exists between socio-cultural, economic and environmental systems within the context of a definable landscape, and they cannot be addressed in a reductionist and deterministic manner” (Fairbanks et al. 1999). Integrative approaches in landscape research (and planning) can contribute to overcome the overspecialization and fragmentation of environmental sciences, policies and education which lead to fragmentary attempts in the solution of environmental problems, and they may help to close the sometimes wide gaps between theory and practice. That all is not new; it was already drafted by the fathers of landscape ecology, by Troll (1939), Schmithüsen (1942), Neef (1967) and others. Neef (1983) wrote in repetition of earlier ideas, that “landscape research as an applied science has to give special attention to the metabolism between human beings and earth, ... between nature and society.” According to Naveh and Lieberman (1984), landscape ecology

was born as a human-related science. Also the demands for landscape ecology to consider ethical / cultural aspects (e.g., Swouden-Svobodová 1991, Naveh 1995, Nassauer 1999) have predecessors: Troll (1950) emphasized that an integrative landscape perspective has to include not only nature but also culture and the traditions of the people. The holistic principle which was postulated already by Smuts (1926), culminates in the “Total Human Ecosystem as the highest level of co-evolutionary complexity, integrating humans and their total environment in our biosphere and technosphere landscapes with emerging properties not existing at the lower levels” (Naveh 1999); i.e., the whole is more than the sum of the composing parts. Landscape as a holistic system represents a part of the ‘Total Human Ecosystem’. Increasingly, thinking and acting humans are regarded as an inherent part of the landscape which is defined as a “spatial and mental unity of the interrelated subsystems geosphere, biosphere and noosphere” (Tress and Tress 2000). Such a broad landscape conception unifies the variety of ecological, aesthetic, social and psychological aspects, and it philosophically supersedes the contradiction between natural sciences and humanities. I doubt, however, that the term landscape ecology is the most favourable one for such a broad ‘meta-science’. Besides, we should accept that – despite the absolutely necessary emphasis on the holistic principle – the examination of the totality of facts and dependences in the highly-complicated phenomenon landscape represents a cognitive overtaxing (it demands too much of humans intellectually). Landscape ecologists and planners cannot consider ‘all things’. Demands leading to this could not be realized and would be remote of everyday life. Holism, however, doesn’t mean the inflationary (i.e., the far too frequent) use of the term landscape ecology for all appearances which are related with landscape in the broadest sense (see Different definitions section).

The role of geography The holistic principle is embodied in both mother sciences of landscape ecology: in ecology with its ecosystem approach and in geography which attaches great value both to spatial aspects and to comprehensiveness (e.g., geocomplexes). The space-related processing and structuring of aggregated, integra-

762 tive parameters belong to the most essential tasks of geography. There are several geographical principles which are often forgotten now in the course of detailed analyses, but which may provide a good basis for wider generalization of both a methodological and theoretical nature. Such principles are, e.g., the hierarchical ordering of geocomponents (landscape factors), partial geocomplexes, discontinuity of natural environment (applicability from the point to the area), regionalization, landscape synthesis (Pietrzak 1998, Solon 1999). As a consequence of the astronomical development of landscape ecology, geography has only a minor part (Finke 1994). Another reason was emphasized by Neef (1984): For a long period it had been assumed that nature and society differed so much in their constituent causal relationships that a connection between the two could not be admitted. ... this tended to be the argument for declaring physical and economic geography to be two distinct sciences which were to be strictly separated. However, one decisive mistake was made in this. Geography does not concern itself with natural systems and social systems, but with landscape regions and their utilization. Besides, many geographers turned to special issues, which probably can be covered by representatives of other disciplines as well or even better. They left the holistic view which actually distinguished geography from other disciplines. A recollection of the landscape as a complex part of the earth’s surface, and the consistent application and further development of geographical principles mentioned above, would be a fundamental supposition to strengthen geography’s identity.

Transdisciplinarity/complementarity It is necessary to take the holistic character of landscape ecology into account, including methodologically. This means less differentiation of branchspecific procedures and looking for bridges which allow connection of specific views (Leser 1997), since the “landscape perspective is full of promise for the realization of the integration of different sciences” (Farina 1998). For Richling (1994) and Moss (1999) landscape ecology is ‘the marriage of biology and geography’. The goal for landscape ecology is to come out of

monodisciplinary restrictions (Neef 1985) and develop to a fairly comprehensive multidisciplinary field. “A simple understanding of landscape ecology as the integration of several disciplines (geography, ecology, ...)”, however, “is not acceptable either for landscape ecologists or for specialists in classical disciplines. A mere combination of disciplines does not solve the specific landscape ecological problems. What actually is specific to landscape ecology? The key factor is the specific landscape-ecological problem...” (Miklós 1996). Landscape ecology is regarded as a holistic transdisciplinary science (Naveh and Lieberman 1984, Naveh 1995; 1999, Miklós 1996), working not only between but above the ‘mother sciences’. Transdisciplinarity means knowledge and research of complex problems beyond special disciplines. The scientific questions are defined and solved independently of particular disciplines (Jaeger and Scheringer 1998). Striving for a unification of landscape ecology (e.g., Wiens 1999b: “Landscape ecology ... must become conceptually and operationally unified.”) leads to the question: In what way can we master the diversity of the landscape sphere? Is it possible with a unified approach, anyway? It is hardly possible for practical research to realize the comprehensive perspective of landscape ecology (which is based on the model of the complex spatially related landscape ecosystem) through only one discipline. Inevitably, several disciplines are involved in the investigation of the landscape ecosystem. It is necessary to be aware of the fact that each of these different views has a selective character and grasps only a part of the complex reality (Leser 1997). Landscape ecology “is an interesting mixture of subjects and motivations for interactive work, as it brings together different viewpoints” (Golley and Bellot 1991 in Drdoš 1996). In my opinion, landscape ecology cannot reflect all facts and relations. But it can and should put special issues into the overall context of nature-environment-society. Rightly we can say that the principle of complementarity is valid in landscape ecology, too. This term was created more than 60 years ago by Niels Bohr for nuclear physics: On the one hand, light, electrons and other elementary objects react as waves, on the other hand as particles. The appearances of waves and particles both describe one part of the reality. One description alone doesn’t give an adequate explanation of all observations. For the equal use of two ‘pictures’ (statements) which are mutually exclusive, Bohr created the term ‘complementarity’. A simple laying of

763 one picture on top of the other is not possible. The pre-condition for an actual synthesis of both pictures is a new dimension; an enlargement of comprehension in nature description. Bohr himself supposed that complementarity is a general dialectical principle in scientific research. This principle was introduced to geography in the 1980s (Buchheim 1983, Neef 1985). Because landscape is a ‘compositum’ (i.e., an assembled construct), a system based on different emerging processes and causalities, it cannot be analyzed by only one scientific approach. Different aspects are possible (Neef 1967). This is the meaning of complementarity in geography (Neef 1985), and respectively landscape ecology: the parallelism of independent research disciplines is not a scientific shortcoming, but a necessity in the investigation of geographical (i.e., landscape) complexes. Landscape as a very complicated phenomenon is analyzed and described from various points of view by different scientific approaches and disciplines. To gain a comprehensive picture of the landscape, all the manifold ecological, social, cultural, psychological aspects must be taken into consideration.

The key position of land(scape) evaluation Landscape diagnosis An urgent goal in landscape ecology is to achieve “a strong theoretical and methodological base” (Moss 1999). Especially, it is necessary to promote the holistic approach. The question, how – going beyond general statements – can be realized; how to implement the specialists’ knowledge into holistic approaches and how to introduce this in practical land management/landscape planning? We are not at zero, a lot of preliminary work has been done. Among various approaches only some can be mentioned here. It is true that “landscape ecology as a science is to provide a firm foundation for applications, it needs more than an array of disparate findings about, for example, the effects of fragmentation in this or that system, on this or that kind of organism”. It requires more than general statements of the form ‘scale matters’ or “all ecosystems in a landscape are interrelated. It requires a core of concepts, principles, methodologies, and predictive theories that generate specifics from generalities” (Wiens 1999b). But I don’t agree that landscape ecology has no “unifying conceptual structure or body of theory”

(Wiens 1999b). For example, in Central Europe, especially in Germany, over the last few years, landscape research resulted in the development of an essentially coherent, highly consistent concept of landscape diagnosis and those areas of land management that were based thereupon. Landscape diagnosis is based upon the results of landscape analysis which, as a field of scientific research and inventory, serves the determination of the landscape structure (components, space, and time structure) with respect to its natural, utilization-related, and dynamic characteristics. Landscape diagnosis has as its primary objective to systematically and methodically determine the capability of landscapes to meet various social requirements and define limiting or standard values, respectively, for securing the stability of natural conditions and for, if possible, increasing of performance capacities (Haase 1990). The term landscape diagnosis was introduced in Germany in the 1950s (Lingner and Carl 1955) following medical diagnosis. In Poland, but also in other countries, specificity of landscape ecology manifests itself in an integrative approach to the object of research, i.e., landscape treated together with man and the effects of his activity, approaching in a structural, functional and visual aspect. Landscape ecology encompasses the analysis of landscape components and their interrelations, identification of spatial natural units, the hierarchical classification and evaluation of the systems of natural environment for various forms of human activity, as well as diagnosis of the way of organization of natural space (Richling 1994). There is no question that only a description of the landscape is not sufficient for planning purposes. A purposeful processing of the analytical data is necessary, i.e., the combination of results of scientific exploration and measurements with technical and economic parameters and, finally, the transformation of geosynergetic and ecological parameters into economic and social indices ... (transferring naturalscience categories to social-science categories in the field of landscape research Neef 1969, Haase 1990, Bastian 1998a). The “transformation problem” includes – as a crucial step of

764 landscape diagnosis or “the core of the application value of landscape ecology” (Zonneveld 1995) – the evaluation of landscape characteristics with respect to social requirements and functions. Thus, the gap between natural scientific facts (e.g., structures, processes and all analytical parameters which we are dealing with, such as habitat networks, patches and matrices, patterns and heterogeneity) and socioeconomic aspects can be bridged. Landscape functions A fundamental help to realizing the transformation problem, i.e., the step from categories of nature to those of society (and vice-versa), is the assessment of landscape functions. It is not a matter of landscape functions in the sense of “fluxes of energy, mineral nutrients and species between landscape elements” or “patch-matrix interactions” (Forman 1981), but in their direct relation to human society. The approach evaluating landscapes with regard to natural potentials/landscape functions has been applied in landscape ecology and planning for many years (e.g., Neef 1966, Haase 1978, Mannsfeld 1979, Ružiˇcka and Miklós 1982, Bastian and Röder 1998, Bastian and Schreiber 1999), such as ecological functioning, usability, and carrying capacity. Examples of such landscape functions are: (potential) biotic productivity, resistance to soil erosion, water retention capacity, groundwater recharge, groundwater protection, habitat function, and landscape potential for recreation. Landscape visions The problem of ecological goals/landscape visions (in German, ‘Leitbild’) is a further expression of connecting natural science and society. Presently, there is much discussion about this in landscape planning and nature conservation. Such goals or visions are seen as providing a solution where we shall choose different alternatives in conservation and utilization of nature and environment (Bastian 1998b). Necessarily, there are both natural scientific and social points of view. It is a real challenge for a transdisciplinary landscape ecology to contribute to the elaboration of scientifically based ecological goals/landscape visions which are accepted by human society.

Conclusion Favouring the holistic concept of landscape ecology, we should also pay attention to special aspects which are to integrate into a comprehensive theory. The more complex a system is, the more complicated is the solution of questions and problems. There are enough difficulties when combining abiotic and biotic aspects. To bridge the gap to social aspects (the transformation problem) is much more complicated. This is still a wide field for research. There are also still essential deficits in the practical application of scientific results and knowledge. Communication gaps between ecology and the design/planning disciplines seem to have their roots, first, in the different approaches of the landscape ecologists’ scientific descriptions versus the practitioners’ artistic or social value-driven work. Second, a lack of cooperation both in research and practical projects enlarges these gaps (Ahern 1999). Often enough, landscape planners and land users (e.g., farmers) also talk at cross purposes. We also should diminish our euphoria concerning the general possibilities of planning landscape development, anyway. There are thousands or millions of actors in a landscape with diverse ambitions. How do we include these ambitions into planning? Which factors and processes influence landscape development. In what way can we regulate it? What consequences for different landscape types result from globalization? How can we protect our most valuable old cultural landscapes? What about the diverging tendencies of land use intensification and urbanisation on the one side and the progressing marginalization on the other side? If we solve one problem, two new questions are opened up. There is a huge amount of work. Let’s get down to it!

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