Capitalising on multiplicity: a transdisciplinary systems approach to landscape research

Landscape and Urban Planning 57 (2001) 143±157

Capitalising on multiplicity: a transdisciplinary systems approach to landscape research BaÈrbel Tress*, Gunther Tress* Alterra Green World Research, Landscape and Spatial Planning Department, P.O. Box 47, NL-6700 AA Wageningen, The Netherlands

Abstract Different disciplines have landscape as the focal point of their research. They are successful in presenting new ®ndings about landscapes within their specialisation, but collaborationÐand thus, transfer of knowledge across disciplinary boundariesÐis seldom realised because a common approach that bridges the gaps between disciplines is missing. Instead, different landscape concepts exist side by side. Yet, cooperation is required to tackle the various environmental and social problems related to landscapes. This paper provides an overview of the historical development of landscape concepts originating from different cultural and scienti®c trends, and presents a new complex concept of landscape, which is designed to enable transdisciplinary landscape research. The transdisciplinary landscape concept is based on ®ve dimensions of landscapes: the spatial entity, the mental entity, the temporal dimension, the nexus of nature and culture, and the systemic properties of landscapes. In contrast to other approaches, it unites dimensions that are usually the domain of individual disciplines and makes it, thus, possible to capitalise on plurality in landscape research. The concept promotes landscape as the combination of the subsystems known as the geo-, bio- and noo-sphere, and is illustrated by the people±landscape interaction model. The concept can be applied to all human±landscape-related research, but is exempli®ed by two studies that have investigated the relationship between landscape and second-home tourism, and landscape and farming, respectively. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Landscape research; Landscape ecology; Transdisciplinarity; People±landscape interaction; Systems thinking; Holism; Secondhome tourism; Farming

1. Introduction `Landscape' is a seemingly familiar term, in research and practise as well as in everyday language. Yet the situations in which we use it and its connotations are changing over time. In everyday language, changes in the broader meaning of a term are passed on through ordinary communication processes and some vagueness in meaning may not be problematic. * Corresponding author. Tel.: ‡31-317-474616; fax: ‡31-317-419000; URL: http://www.tress.cc. E-mail addresses: [email protected] (B. Tress), [email protected] (G. Tress).

0169-2046/01/$20.00 # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 9 - 2 0 4 6 ( 0 1 ) 0 0 2 0 0 - 6

In science, where `landscape' is the focal point of a range of disciplines and a ®eld of interest for many, a more precise understanding of the connotations of the term is essential. How can we research landscapes if we do not de®ne our study object, the landscape? Thus, a theoretical debate, a rede®nition, is necessary so the term `landscape' re¯ects current usage. Clear theoretical concepts are the preconditions for any scienti®c work and its transfer into practice. Within landscape research, different concepts of `landscape' exist, suggesting the application of different approaches (Muir, 1999). These approaches vary depending on whether they were developed within the natural, the social sciences, the humanities

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or the arts. Furthermore, the speci®c disciplines within these ®elds have developed their own traditional applications and concepts of the term and have successfully arrived at new insights into landscapes. As a consequence, important knowledge has been gathered and valuable results have been presented within each discipline working with the `landscape'. But like computer systems developed by different companies, although each may work well they are incompatible with one another, hindering exchange of knowledge and causing problems as soon as disciplinary limits must be transcended (Nassauer, 1995, p. 236). To us, landscape research is a transdisciplinary endeavour (Jantsch, 1970) that includes approaches from the natural and social sciences as well as from the humanities, landscape architecture, and the arts. Transdisciplinary landscape researchers try not only to coordinate scienti®c approaches, but also to communicate with society, which becomes part of the research process. Landscape research is, thus, broader than landscape ecology, from which it nevertheless derives important knowledge. A greater degree of collaboration among landscapeoriented disciplines is frequently prescribed because today's environmental and social issues are global in scope and so complex that single disciplines cannot provide the knowledge necessary to understand or solve them (Naveh, 1995a, 2000; Di Castri, 1997; Hobbs, 1997; DeÂcamps, 2000; Moss, 2000; Fry, 2001). Landscape-related issues often touch on environmental, social, cultural, aesthetic and economic issues simultaneously. How can landscape researchers then effectively work together to solve these problems if they refer to different theoretical constructs? If they have no common theoretical foundation, on which foundation should they rely? If we agree that landscape research is a science oriented towards the solution of problems related to landscapes, then it is imperative to have a reliable theoretical foundation that enables scientists and experts in different areas to work together (see Naveh, 1995a; DeÂcamps, 2000). We need a theoretical concept that enables a transdisciplinary approach to landscape research. On this basis, the paper introduces a transdisciplinary landscape concept, which comprises ®ve dimensions, and is illustrated by the people±landscape interaction model. We will show the application of the concept with two case studies. A brief review of historical and

current landscape concepts will serve as necessary background information for the transdisciplinary landscape concept. With backgrounds in the natural and social sciences as well as in the humanities, we set out to design both concept and model to be equally attractive to all ®elds dealing with landscape research. This paper should be read as an invitation for joint future research on landscapes. A joint effort will improve the effectiveness of landscape research and maximise its knowledge for deeper insights into landscapes. 2. Past and present landscape concepts 2.1. Early landscape concepts By the early Middle Ages, the term `landscape' was already in use. Early references to the term `landscape' exist in most of the Germanic languages. The oldest written evidence is found in Old High German manuscripts. The phrases `lantscaf' or `lantscaft' appear in the Tatian manuscript Codex 56, written around the year 830 A.D. (Braune and Ebbinghaus, 1969; SchuÈtzeichel, 1969). The term `lantscaf' was used to translate the Latin term `regio', meaning area, territory, region. In the medieval period, the term was synonymous with `region' and `territory', one of the meanings still in use today (Hard, 1976). Olwig (1996, p. 634) shows convincingly that the German `Lant(d)schaft' in medieval times already had a social and legal sense related to customary laws. As `lantschap' the term was also already known in the Middle Dutch period, starting in the 13th century. Here it described an administrative entity, a certain area, or was used as a synonym for land and one's native country (Geerts and Heestermans, 1992; Vries and Tollenaere, 1991). Old English manuscripts, i.e. the Anglo±Saxon Genesis, use the term `landscipe', again as a synonym for `region'. At the end of the 16th century, however, when Dutch landscape paintings came to England, a `landscape' referred to a piece of art, a painted scene (Onions, 1969, p. 514; Simpsons and Weiner, 1989, p. 628). In these paintings, landscapes were no longer only the backdrop for ®gures as they had been throughout the Middle Ages, but had become the subject in their own right. In the 15th and 16th

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centuries, landscape painting emerged as an independent genre and became popular in the 17th and 18th centuries. Landscape paintingsÐespecially those by Lorrain and PoussinÐare often described as representations of an idealised reality, but one wonders to what degree this was actually the artists' intention. It can be assumed that the artists represented natural features as they saw and perceived them but not necessarily with the intention to idealise. Roethlisberger (1998) points out that calling Lorrain's art `idealised' or `ideal' is an invention of 20th century art historical literature. Contemporaries of the painter praised the naturalness of his landscapes, their similarity to `real' nature. Looking back on early landscape concepts exposes the tension between landscape as region and landscape as perception. The meaning of landscape as material reality versus mental perception is still one of the basic questions in the landscape debate. 2.2. Introduction of landscape concepts into science In the transition from the 17th to the 18th century, Alexander von Humboldt, Johann Wolfgang von Goethe, Carl Ritter, Henrik Steffens and others introduced the term `landscape' into science. Humboldt glossed the term as the physical reality of a landscape. To him, landscape was the sum total of the characteristics of a region (see Humboldt, 1849, p. 252). In the second half of the 19th century, the complex holistic meaning of landscape disappeared (SchmithuÈsen, 1968, p. 31), due to the division of science into single disciplines and an increasingly analytical way of thinking. The existing meanings of landscape were analysed separately and so were the parts of landscape. A term like `Landschaftsbild' [landscape scenery] was beyond scienti®c treatment. However, at the turn of the 20th century, Vidal de la Blache and others revitalised `landscape' as a scienti®c concept. It was a commonly held attitude in this period that one should regard the totality of characteristics of a region and unite them mentally. Sauer introduced the term to American Geography in 1925, drawing on the ideas of German Romanticism and natural philosophy (Sauer, 1963; Olwig, 1996, p. 643). To Sauer, landscape was ``an area made up of a distinct association of forms, both physical and cultural'' (p. 321). Hartshorne (1939, p. 154) criticised

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this concept; he found the duality of the term confusing and suggested its removalÐat least from geographical inquiry. This form of dismissal was only a precursor of what would become symptomatic for 20th century landscape research: the complex meaning of landscape and holistic inquiry into it disappeared due to the organisation of science into disciplines and enforced specialisation of scientists. A range of landscape concepts came into existence, each of which served the speci®c purposes of a speci®c discipline. 2.3. Dialectic of landscape concepts in the 20th century Carl Troll was one of the most in¯uential landscape researchers in physical geography. He understood landscape as a process-based `WirkungsgefuÈge' (a complex of mutual in¯uencing factors), a real `Gestalt' of nature and human enterprise (Troll, 1968). Troll's interpretation of the term `landscape' and his unwitting creation of landscape ecology as its own ®eld of research in¯uenced geographically motivated landscape research for decades. From the 1950s to the 1970s, landscape in, for instance, physical geography was perceived as natural area plus land use (Neef, 1967; Haase and Richter, 1980; Haase, 1999). This conception included the cultural as well as the physical dimension. The `natural' landscape was investigated, which included the changes people had made to it through land use. However, only humanmade installations and establishments, and human actions that conditioned them, were considered, not people as living and thinking individuals. This perception with a strongly natural scienti®c orientation can be found until the 1990s by Leser (1976). It is also evident in the schools of landscape ecology established by Risser (1987); Risser et al. (1984); Forman and Godron (1986), and Sanderson and Harris (2000). The subjective qualities of landscape that have been problematic for landscape researchers rooted in spatially oriented natural sciences, became of interest to those who did not agree with the positivist movement within science (Muir, 1999, p. XVII). The landscape concept was reformulated in order to ``allow for the incorporation of individual, imaginative and creative human experience into studies of the geographical environment'' (Cosgrove, 1985, p. 45). Here, landscape

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is seen as symbol, icon or myth, mirroring the cultural and social structures of human societies (Cosgrove, 1984, 1993; Daniels and Cosgrove, 1988). This does not mean that landscapes are immaterial, but that they are as real or unreal as their representations. ``A landscape park is more palpable but no more real, nor less imaginary, than a landscape painting or poem'' (Daniels and Cosgrove, 1988). To Cronon (1995, p. 20), landscape as well as nature is ``a human idea, with a long and complicated cultural history which has led different human beings to conceive of the natural world in very different ways''. Appleton (1975, 1986) and Bourassa (1991) make the shift from the subjective qualities of perception to the scenic object as the ultimate determinant of perception. Appleton was the ®rst to formulate a consistent theory on landscape aesthetics, grounded in the `habitat' and `prospect-refuge' theory. This basically evolutionary-biological approach was further developed by Bourassa (1991), who stressed the biological, cultural and personal modes of aesthetic experience and observes landscape to be a ``particularly unwieldy aesthetic object. It is a messy mix of art, artefact and nature, and it is inextricably intertwined with our everyday, practical lives'' (p. XIV). Such historic meanings are all somehow present in the current understanding of landscape. They form overlapping, oscillating, and stretchable layers of meaning. Taken together, they are like a collage of pieces taken from different periodsÐan amalgam of styles in the best post-modern sense. 2.4. Towards a holistic view of landscapes The few examples mentioned above do not give a complete picture of landscape research, nor were they intended to, but they indicate what may have been the chief shortcoming of landscape research in the 20th century. Natural scienti®c oriented landscape researchers investigated the physical parts of the landscape. They focused on the examination of geomorphological or hydrological processes, the spread and distribution of plant and animal species. Or they investigated landscape heterogeneity, dynamics and change, focusing on material and spatial processes and patterns of distribution, as well as on the technical installations and changes to infrastructure made by humans and their effects on the environment.

In contrast, researchers rooted in the social sciences, humanities and the arts, dealt with landscape as a human idea, cultural invention (i.e. works of art that re¯ected personal experiences), social product, and aesthetic object, investigating its shifting meanings in relation to human history and its manifestations of property and power. Many researchers from the natural sciences stressed the importance of human beings as an in¯uencing factor and many researchers from the social sciences and humanities were very aware of the physical± material reality of landscape. As Cronon (1995, p. 21) puts it, a landscape made of pure idea, a fantasy, ``is so ludicrous that it is hard to see how any sane person could hold it [. . .]. But at least for humanity, a world of pure matter is no less absurd, for ideas do exist and have real consequences in the world''. One could, thus, come to the conclusion that the two realms had not been that far apart, but in fact, they were. Even if researchers rooted in the natural sciences included human effects, they did not equally consider the mental and cultural parts of landscapes (Nassauer, 1995, p. 229). And researchers rooted in the humanities, social sciences and arts did not relate the human perceptions and ideas of landscapes to the geological and biological reality. This imbalance will be further elaborated on in the following paragraphs, where the transdisciplinary landscape concept is developed. Researchers with different theoretical concepts have different attitudes and worldviews; they develop different research questions and use different methods to get answers to them. Finally, they present different results on the same subject, the landscape, which are all correct in their limited way, but fail to grasp the full reality of landscapes. Only towards the end of the 20th century were attempts made to develop a holistic, broader and more balanced view of landscapes. Naveh (1990, 1999); Naveh and Lieberman (1994), and Naveh and FroÈhlich (1996) in particular moved towards a transdisciplinary landscape approach, compelling others to see landscapes as a tertium comparationis for several disciplines. At the end of the 20th century, the way became clear for landscape research as a metadisciplinary science. We argue for a transdisciplinary systems approach to landscape research, not to make different disciplines agree upon a distinct concept of landscapes,

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but rather to facilitate exchange of knowledge among disciplines and, thus, make it possible to arrive at deeper insights into landscapes. 3. The ®ve dimensions of the transdisciplinary landscape concept The transdisciplinary landscape concept is rooted in the different historical landscape concepts and is their logical culmination. The concept allows for transdisciplinary landscape research and is built on ®ve dimensions (B. Tress, 2000; G. Tress, 2000). These ®ve dimensions can be described separately, but the landscape concept, as introduced here, unites all dimensions. For methodological reasons they are described one after the other, but in landscapes they do not exist separately. The ®ve dimensions are:     

landscape landscape landscape landscape landscape

as as as as as

a a a a a

spatial entity; mental entity; temporal dimension; nexus of nature and culture; complex system.

3.1. Landscape as a spatial entity Rooted in the `regio'-meaning of earlier landscape concepts (see Section 2.1), landscape has a physical± material dimension and thus, is a palpable reality. Landscapes are so real that we can walk upon them, ¯y over them, recreate them or measure them. In the long tradition of geographical landscape research, as well as in landscape ecological research, landscape as a spatial entity was the cornerstone of all scienti®c debate about landscape, to which other meanings were added (see Troll, 1968, p. 4; Paffen, 1973, p. 76; SchmithuÈsen, 1973, p. 158; Forman and Godron, 1986, p. 11; Zonneveld, 1988, p. 6; Bastian and Schreiber, 1994, p. 30). Today, there exists wide agreement about the fact that landscapes have a physical reality, a spatial dimension. Traditionally, the spatial±material dimension of landscape is manifested in the abiotic, biotic, and artefactual spheres (Naveh, 1995b calls the last `technosphere'). All three spheres are related to each other. The abiotic components of geosphere (e.g. rocks, water) form the conditions for life in the biotic realm,

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the biosphere, consisting of ¯ora, fauna and including humans. People form artefacts (like buildings, roads, cars, planes) out of the abiotic and biotic elements. People areÐas living beingsÐpart of the biosphere and as such, they are part of the physical±material reality of landscapes. 3.2. Landscape as a mental entity Whenever people get in touch with the physical reality of landscapes (that is the ®rst dimension), they respond with their minds through re¯ection, feelings, and imagination. This dimension of landscape is rooted in the aforementioned understanding of landscape as a mental perception (see Section 2.3). It is mind and reason that distinguish humans from other beings. Perception, the `perceiving' of landscapes is not dependent on purely sensory data from eyes and ears. It is in¯uenced by our minds' ability for selective perception, which is always embedded in the social and cultural contexts of individuals and society (Tuan, 1979, p. 89; Muir, 1999, p. 115). Meinig (1979, p. 33) states that ``landscape is composed not only of what lies before our eyes but what lies within our heads''. Our view of landscapes is a product of culture and culture shapes landscape (Naveh, 1998, p. 30). Therefore, the same landscape can be perceived differently by different observers. To consider the mental dimension of landscape is to regard people not only as external disturbance factors or as external steering mechanisms, causingÐmostly unwantedÐchanges in a physical ecosystem. We must recognise that landscape has developed in a coevolutionary process with people. Landscape would not exist in its present state without human in¯uence. Vernadsky (1945) coined the term `noosphere' (from the Greek, `noos', or mind) for the mental sphere in which humans function. He recognised that people were a determining factor in geological and biological processes on Earth due to their mental abilities. He concluded that the human species was transitioning from the biosphere to the noosphere. But the term is not used in this sense here. To us, the noosphere is not following the biosphere; rather, the noosphere is a third ®eld of equal importance. The noosphere is the mental space of people, structured by perception and adaptation. By means of the noosphere, human beings are able to perceive and to in¯uence the

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physical±material reality of the geo- and bio-spheres. Both motivations and the actions that result are part of the noosphere. The two dimensions of the landscape concept presented illustrate the dualistic relationship between people and the landscape. On the one hand, people areÐas part of the biosphereÐpart of the physicalmaterial reality of landscape and as such they are not a precondition for its existence. On the other hand, peopleÐas thinking, acting, and re¯ecting beingsÐ also create the landscape. It is mental re¯ection that ®rst creates landscape. As acting beings, people in¯uence the natural conditions and create artefacts, which shape and organise their environments. As beings capable of re¯ection, people have the ability to take themselves out of the landscape and to re¯ect upon it from this perspective. This is possible in spite of the fact that people simultaneously are part of the landscape and create it by means of their mental abilities. Thus, they relate themselves to landscape and are part of it at the same time. 3.3. Landscape as a temporal dimension Both the spatial and the mental dimensions of landscapes underlie the third, the temporal dimension. The overview of historical landscape concepts showed that the understanding of landscape as a `regio' and as a perception changed over time. Landscapes are not static, but subject to ongoing change. Landscape change and development are intrinsically linked to the passage of time. Space is the issue on which landscape researchers have often focused (see Section 3.1). Time, in contrast, has not been treated equally, often relegated to the background. Landscape functions have often been explained with static models (see Vink, 1983). And the perception of a static landscape is still present today. In the ®rst third of the 20th century, Clements (1916) developed the theory of succession and climax in plant ecology, which was adopted by many ecologists. Accordingly, landscapes were perceived as developing toward a ®nal state or as being in their ®nal state, their climax. Consequently, descriptions of landscapes emphasised movement toward a climax state, the state that should be conserved and leaves no room for further development. The succession±climax dogma should be given up, because it is inappropriate

to explain the dynamic changes that occur in a landscape (Naveh and Lieberman, 1994, p. 9). It is important to be aware of the relationship between time and space. To physicists, space and time are closely related. At the beginning of time, space was almost zero, but the more time has passed, the more space has expanded (Greene, 1999, p. 411). This process is still going on. What landscape research can learn from these ®ndings is the fact that space and time are expressions of each other and that space changes through time, and time through space. Many peoples' perception of space and time are changing and with it their perception of landscapes. People in early times did not have long life expectancy and their circle of activity was limited to places they could reach on foot. As late as the Middle Ages, an average person's perception was limited to the constricted space of one's hometown or village. Time and space in their lives must have been operating on a different scale from the present day, in which a trip to another continent is a common occurrence for many people. The temporal aspect changed together with the expansion of peoples' activity space. It may still be possible to measure time and space with the same entities as centuries ago (days, hours, minutes, kilometres, metres, and centimetres), yet what these entities mean to people is different. A kilometre in the 15th century did not mean the same thing as it would today, and neither did a day. So time and space are not ®xed terms in our minds. Similarly, our perception of time and space results in different perceptions of the landscape. The temporal dynamic of landscapes concerns all landscape dimensions and changes appear on all scales. What Laszlo (1972) states about groups of people and of societies is also valid for landscapes as a whole: ``Individuals come and go; [societies] remain. It is not that they are immune to changes themselves, but they do not change with the changes in their membership''. While single landscape elementsÐi.e. soil particles, plants, buildings, and water moleculesÐare being exchanged constantly, the landscape as a whole persists. In a similar way, peoples' ideas and perceptions of landscape elements or cultural conventions endure across generations. The temporal dimension of landscape is not always necessarily connected to a noticeable change because changes occur slowly and thus, people do not become aware of them.

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3.4. Landscape as nexus of nature and culture In the paragraphs above, we addressed the importance of recognising the spatial, temporal and mental dimensions, respectively, of landscapes. These dimensions do not exist separately from each other, but are intertwined. Therefore, we will now focus on the mutual relationships that exist among these three dimensions. Since humans evolved, they have been in¯uencing and changing landscapes. Today's landscapes are the visible product of this historical process. Landscapes come into existence neither solely from natural processes nor solely from cultural processes. Naveh (1995a, p. 44) coined the de®nition of landscape as ``the tangible meeting point between nature and mind''. This concept implies that people do not only in¯uence landscape, but landscape also in¯uences people. Consequently, landscape is the very point where nature and culture come into contact, where the material and mental spheres come together. Nature and culture are not counterparts, but rather complementary, overlapping entities. Natural sciences, social sciences and humanities, which research this subject, should also be seen as complementary entities. To regard the landscape as a mental entity has its roots in the social sciences and within artistic approaches (see Section 2.3). It is not a common attitude in landscape ecology research, which is based on a natural scienti®c view (Nassauer, 1995; Palang et al., 2000). On the other hand, studies of landscape perception and cultural aspects of landscapes do not treat the multiple abiotic and biotic facets of landscapes (Hard, 1973; Bourassa, 1991; Bender, 1993). This is a problem when trying to investigate and to understand landscapes as a whole. As mentioned above, all these branches have made valuable contributions to the understanding of landscapes. However, it is essential, to have a broader view when trying to solve the problems related to future landscapes. Such an integrated approach, combining nature and culture in landscape research is called for by several researchers, including Gustavsson and IngeloÈg (1994); Nassauer (1995, 1997); DeÂcamps (1997, 2000, 2001); Di Castri (1997); Antrop (1998, 2000); Naveh (1998, 2000, 2001); Bridgewater and Bridgewater (1999);

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Makhzoumi and Pungetti (1999); Luz (2000); Oreszczyn (2000); Roe (2000), and Fry (2001). 3.5. Landscape as a complex system The expression of the ®fth dimension of the landscape concept is the perception of landscape as a system. Systems thinking is a method of scienti®c inquiry that allows one to understand and investigate complex realities (Laszlo, 1972; Checkland, 1986; Capra, 1996). Landscape is a complex system involving the geo-, bio- and noo-spheric subsystems, and their expression over time. Regarding the landscape as a system is to focus on the relationships among these subsystems and see them in the context of the whole and not only as separate entities. The geo-, bio- and noo-sphere, as well as the manner of change over time, can be examined independently of one another, but it is only when the four subsystems are combined that we can speak of the landscape as such. This whole has distinct qualities and a higher level of complexity. Landscapes are hierarchically ordered, with the geo-, bio- and noo-sphere as subsystems and the total human ecosystem (Naveh and Lieberman, 1994) as suprasystem. Insofar as the subsystems of landscape are combined in one system (and consequently are also treated as a single system in research), we are applying a holistic approach (Smuts, 1926). The holistic view perceives reality as a hierarchically ordered combination of wholes: neutrinos, quarks, atoms, molecules, organisms, human society, Earth as total human ecosystem, galaxy, cosmos. Every whole is a system. Antrop argues that, ``Holistic also means that each element receives its signi®cance only because of its position and relationship with the surrounding elements. Therefore, changing one element always means changing the whole in some way'' (2000, p. 18). Holistic thinking ``. . . provides the basis for studying certain wholes or systems, without knowing all the details of its internal functions'' (Zonneveld, 1988, p. 8). As a consequence, it is super¯uous to examine all the elements in a system, including their relationships, before the whole can be examined. As part of the total human ecosystem, landscape is an open system that communicates with its environment by streams of energy, matter, and information. In addition, landscape can be identi®ed as a living system because it is characterised by the three features

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of pattern, structure, and process (Capra, 1996). The pattern represents the general order of relationships among the system's elements. It is valid for all landscapes. Structure, by contrast, represents a particular landscape. It is the way in which the general pattern is realised in one speci®c landscape. The relationship between these two ®eldsÐand this is the decisive characteristic for living systemsÐis in constant renewal. This process points to a new de®nition of the term `life' as a descriptor of everything that is capable of initiating an autopoietic process (Capra, 1996, p. 185). Landscape remains a stable structure (see Section 3.3), but can be recreated at any moment by the continual exchange of energy, matter, and information and therefore, landscapes are autopoietic systems with dissipative structures.

Fig. 1. The dynamic interrelationship of the geo-, bio-, and noosphere.

3.6. The transdisciplinary landscape concept The ®ve dimensions described above have been incorporated into the transdisciplinary landscape concept. The knowledge that has been gathered in different ®elds comes together in this concept, capitalising on the vast multiplicity in landscape research. By landscape, we mean a complex, dynamic system, made up of the interrelated subsystems known as the geo-, bio- and noo-sphere. Due to these coexisting subsystems, landscape is the concrete nexus of nature and culture. As a spatial and mental entity, landscape is part of the totality of the geo-, bio- and noo-spheres. People are part of the landscape by means of their actions and thoughts. Through human thought, landscape also becomes part of people.

Fig. 2. Nature and culture as complementary entities.

1. In the transdisciplinary landscape concept, the noosphere is put next to the geosphere and the biosphere as a third ®eld of equal importance. The geo- and bio-sphere represent the spatial dimension of the concept, the noosphere, the mental dimension. Fig. 1 illustrates how these three spheres interact and in¯uence each other. They form a dynamic system that changes over time, which is indicated by the time arrow.

3.7. The people±landscape interaction model The above-mentioned concept is a theoretical way to understand landscapes. We illustrate the premises that are formulated herein by the people±landscape interaction model, which can be helpful in the application of the concept to the practical investigation of landscapes. It is not a mathematical model that allows for one form of application but a conceptual model that can serve as a framework for research on complex landscape issues. It allows for individual adaptation to ®t speci®c research situations. The model will be introduced step-by-step (see Figs. 1±5).

Fig. 3. The ®ve dimensions of landscape.

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Fig. 4. The landscape and its material interactions with humans.

2. The next ®gure illustrates the dimension of landscapes as a nexus of nature and culture (Fig. 2). The noosphere represents the cultural aspects of the landscape concept, the geo- and biosphere, the natural ones. Nature and culture are visualised with two horizontal ovals: in landscapes, nature and culture are not opposed to each other but complementary. 3. The system dimension of the transdisciplinary landscape concept is illustrated in Fig. 3. When all ®ve dimensionsÐspatial, mental, temporal, nexus, and systemÐare realised we speak of a landscape. The vertical oval visualises this perception of landscape in the model. 4. People play a dual role in the people±landscape interaction. They are part of the biosphere but, as

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re¯ecting and acting beings, they can also set themselves apart from the landscape. The people± landscape interaction is material and mental and proceeds in mutually in¯uencing loops of actions and reactions. Fig. 4 illustrates the material interaction loop. By means of their actions, people affect the landscape, the subsystems bio- and geosphere. In return, these subsystems provide raw materials, space, potential food, and are therefore, the precondition for human existence and action. 5. In Fig. 5, the mental interaction loop is added to Fig. 4. Landscapes also affect people by means of their appearance (reactions are not restricted by time and place). People perceive landscapes and re¯ect upon them, which is to say they also re¯ect about the changes they have undertaken. By thinking and re¯ecting about the landscape, people create a mental image of it. People compare their conceptions (expected reality) with actual perception (perceived reality) and draw conclusions. This comparison in¯uences peoples' subsequent actions as it may cause them to modify future behaviour. In this way, it steers the course of the landscape system. The material and cognitive processes described in the people±landscape interaction model take place between all living systems and their environments; each of us can experience them while observing the landscape around us. 4. Applications of the transdisciplinary landscape concept The people±landscape interaction model and the concept on which it is based can be used to examine people±landscape relations in landscape research in various ways. Two uses will be illustrated in the following examples. 4.1. Second-home tourism and landscape

Fig. 5. The people±landscape interaction model.

Second-home tourism is a phenomenon common in many European countries. In Denmark, the tradition of second-homes goes back more than 100 years. Most second-homes in Denmark are privately owned cottages or houses close to the sea that are used for

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recreational or tourism purposes (in Danish, they are called sommerhus). Since the early 1980s, international tourism in Denmark has been driven by secondhome recreation. The number of second-homes has increased dramatically. Today, about 216,000 secondhomes can be found, mainly along coastal areas. Many second-homes are used year-round, both by domestic and foreign tourists. At present, second-home tourism is the most important sector in Danish tourism (see Tress, 2002). The study reported here (Tress, 2000) investigated the relationships between second-home tourism and the landscape in Denmark. The research was motivated by the critical need for carefully considered management of second-home areas in coastal landscapes in Denmark. To determine whether secondhome tourism was viable for future coastal recreation, its impact on the landscape had to be foregrounded. The study applied the transdisciplinary landscape concept under discussion. Coastal landscapes result not just from bio- and geo-spheric conditions, but are shaped by the noosphere as well. Second-home tourists are not only part of the biosphere but, due to noospheric conditions, are able to shape the coastal landscape. This interaction is changing over time. In keeping with the idea that the landscape is a nexus of culture and nature (see Fig. 2), the study had to consider both natural and cultural aspects of the relationship between second-home tourism and the landscape. The relationship is not unidirectional. Not only does second-home tourism impact the landscape, but the landscape itself is the main factor in creating the phenomenon of secondhome tourism. The relationship between second-home tourists and landscape is not a juxtaposition of independent problems, but a complex system of relations among different elements and positions. The relations expressed and visualised by steering loops in the people±landscape interaction model (see Figs. 4 and 5) can be identi®ed in the relationship between second-home tourists and landscapes too. Second-home tourism has a material impact on the spatial dimension of the coastal landscape. Tourism activity, travel and second-home construction have to be considered here. On the other hand, the spatial dimension of the landscape offers space for tourism activity to occur. However, a discussion of the material consequences of the second-home landscape interaction would not cover

the relationship suf®ciently. Investigating the interaction cannot be done without considering the motivations behind second-home tourism and also the tourists' perception of landscapes. The coastal landscape is subject to tourists' expectation and ideas that shape it anew. The mental steering loop of the interaction has to be considered too. The tourists have expectations towards the landscape that stimulate the tourism activity, but the coastal landscapeÐand its perceived material consequencesÐalso in¯uences the tourists' expectations and activities. The relationship is thus, continually modi®ed by ongoing perception and use, which impacts further actions. In this way, second-home tourists and coastal landscape mutually in¯uence each other. The application of the concept resulted in recording more than just the environmental repercussions of second-home tourism. It was necessary to focus also on the landscape's suitability for tourism activity, on tourists' expectations and motivations for the secondhome stay, and on the way tourists perceived the coastal landscapes and repercussions on it. The questions about future development of second-home areas in Denmark could be addressed only by broadening the scope of the research activity. This approach determined the choice of methods used in the research process, which were rooted in the natural sciences, social sciences, humanities, and the arts. The study surveyed about 1000 second-home tourists and collected data on more than 625 second-homes. Results were drawn from questionnaires, interviews and personal communications, ®eld studies, mappings, and interpretations of aerial photographs. The results drawn from the study were quite diverse and threw new light on the relationship between second-home tourism and the landscape in Denmark. The desire to experience an attractive landscape was indeed the main reason for buying or renting a second-home. The study also recorded the enormous environmental impact of construction and use of second-homes. It demonstrated that although awareness of environmental consequences was high among second-home tourists, such awareness had no profound in¯uence on their behaviour and perception. Finally, the results were combined in the design of several `leitbilder' for second-home tourism. `Leitbilder' are condensed visions and fantasies, wishes and hopes of single or groups of second-home tourists.

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They are concepts that exist not only in thoughts but direct actions of second-home tourists. They were constructed to elucidate the different kinds of relationships between second-home tourists and the landscape that make up the complex structure of the people± landscape interaction. 4.2. Farming and landscape Farmers and their activities have a crucial role in shaping landscapes. This observation is also true for Denmark, where still almost two-thirds of the territory is used for agriculture. Since the 1960s, crops in Denmark have been increasingly saturated with chemical fertilisers and pesticides. By the 1980s, marine and terrestrial environments had become threatened by high concentrations of nitrogen and phosphate, evidencing the high costs of this kind of production. Agriculture is of high relevance for the Danish economy as two-thirds of the national export derive from agricultural products. Organic agriculture was brought into discussion as one way to reduce the negative environmental impact of commercial agriculture on the environment. The Danish Government launched a national plan of action to promote organic agriculture, and sought to have 7% of all Danish farms managed organically by the year 2000 (Tress, 2001). The regulations for organic farming in Denmark conform to the regulations of the International Federation of Organic Agricultural Movements (IFOAM, 1997). The study referred to here (B. Tress, 2000) investigated the relationship between farmingÐboth organic and conventionalÐand the landscape. The basic assumption was that organic and conventional agriculture interact differently with the landscape. Organic and conventional agriculture not only have different land uses and different shifting-cultivation practices, but also different paradigms that drive agricultural production, resulting in different attitudes of farmers. The focus was on the farming±landscape interaction in production and non-production areas. The possibility of converting farmers from conventional to organic farming was given special focus, as a major shift toward organic production would change the farming±landscape interaction and thus, result in other landscapes. The people±landscape interaction model was used as a conceptual framework for an integrated assessment of these different aspects.

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According to the transdisciplinary landscape concept, answers to the research questions, necessitated treating the noospheric, perceptional realmÐhow do farmers perceive their landscapes and re¯ect upon themÐas equal in importance to the geo- and bioconditions of the landscapes. To consider the temporal dimension of the concept was to recognise that today's agricultural landscapes in Denmark are the result of interactions between farmers and the landscape since ancient times and that the current situation is only a snapshot in the course of their dynamic development. Acknowledging the systemic character of these landscapes meant uncovering the mutual relationships that exist between the geo-, bio- and noo-sphere and regarding them as a whole. The dual role of humans in the people±landscape interaction, as highlighted earlier, is also valid for farmers. They are part of the physical landscape, but are also able to set themselves aside and re¯ect upon it and their in¯uence upon it. The material and mental steering loops that visualise the people±landscape interaction (see Figs. 4 and 5) can also be found in the farming±landscape relationship. The farmers affect the landscape by sowing, ploughing, fertilising, establishing new ®elds, and rearranging their boundaries. In turn, the geo- and bio-sphere form the basis for agricultural production; they are the precondition for the farmer's existence. The spatial dimension of the landscape determines how agriculture is realised at a certain spot: geomorphology, soils, and climate determine which crops can be grown or which kind of livestock farming is the most suitable. However, the agricultural landscape also impacts the farmer, who perceives the landscape and re¯ects upon it and on the actions and changes he/ she has undertaken. In this way, farmers create a mental picture that is not merely a product of the moment, but is also in¯uenced by economics (market prices), social factors (age, education) and culture (ethical values, aesthetic concepts). The farmer's idea about how the agricultural landscape should appear is compared to actual perception and in¯uences subsequent actions of the farmer (e.g. to make changes in land use, to cut the grass, or to establish hedgerows). It may cause a change in future management of the landscape and thereby steers the future course of the farming landscape. The study surveyed 650 organic and conventional farmers. Production areas and non-production areas

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were compared and contrasted. The mindsets of organic and conventional farmers were determined by asking them about their attitudes toward farming practices (e.g. application of fertilisers and pesticides, pro®t motive, environmental-friendly production, biotope management, and landscape values, among other topics). Conventional farmers' impressions of organic farming were surveyed as well as their motives to convert or to resist conversion to organic agriculture. The scope of the study demanded the application of methods from different academic traditions, quantitative as well as qualitative ones, including a questionnaire, interviews, personal communication, mapping of agricultural areas, map and aerial photo interpretations. The study revealed a high diversity of interactions between farming and the landscape in Denmark. Land use in organic and conventional farming settings vary considerably. Differences in management practices are subtle and involve qualitative issues. Organic and conventional farmers' attitudes towards farming practices coincide to a large extent and vary only on speci®c issues. Few conventional farmers were willing to convert to organic agriculture, but the study showed that an increasing percentage of new organic farmers come from outside the agricultural sector. The results of the study made obvious the heterogeneity among Danish farmers, who come from different cultural and social backgrounds and have widely varying motivations to farm. These characteristics ®nd expression in different farming±landscape interactions, in different ways of farming, and ®nally, in different farming landscapes. These ®ndings are important for agricultural policy and subsidy principles, which should pay more attention to the farmers' background and motivations and see them in relationship to the landscapes. We must not only consider what lies in front of our eyes, but also what lies within the minds of farmers, and establish the relationship between them. 5. Conclusion The complexity of the people±landscape interaction illustrates the dif®culties of system-oriented transdisciplinary approaches within landscape research. One could assume when everything is interrelated, then full understanding could only be reached by dissecting

and explaining each relationship. Of course, this is impossible. But according to Capra (1996, p. 56), a systems-oriented transdisciplinary approach is useful nonetheless because it brings us far closer to this knowledge. It does not support the demand for certainty and strictly uphold scienti®c theories and terms. As per Bohm and Peat (1987, p. 569), knowledge is not a process of continuous accumulation, but a process of continuous changes. When we have presented our concept at different meetings and conferences, we have occasionally been confronted with the question of the value of theoretical debates for landscape research. Is it worth spending time on theoretical debates when faced with the urgent problems of the environment? We see landscape research as a practical scienti®c ®eld, oriented towards solutions to environmental, cultural, social, aesthetic, and economic problems. Nevertheless, without a common concept, landscape researchers are merely individual competitors, who are unable to form a team when necessary. Our discussion and development of a theory has not been done at the expense of practical research. With a workable theoretical concept of landscape, we can more precisely target just what we are researching. We are then able to structure and organise research in a way that it is more effective, goal-oriented, and thus, more capable of solving practical problems. The concept under discussion combines physical± material and cognitive systems. Traditionally, the ®rst are examined by the natural sciences, whereas the latter are investigated within the social sciences and the humanities. Our approach requires the natural and social sciences, humanities and the arts to surmount this tradition and cooperate. Landscape is neither a solely objective nor a purely subjective reality; it is both simultaneously. Thus, its scienti®c examination needs a common effort across traditional disciplines. The examination of geological, biological, aesthetic, historical, psychological, social or economic dimensions in isolation is not appropriate to landscape's complex reality. Landscape research is a futureoriented, pro-active science, and therefore, it is necessary to take on the challenge of looking beyond the boundaries of our own disciplines, our own familiar ways of thinking, and discover common ground with other disciplines. It is necessary to bridge the gap between human and natural sciences in landscape

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research. Then we may acknowledge that we are not only part of the landscape, but that landscape is also part of us. Acknowledgements We would like to thank all the landscape researchers whoÐprobably without knowing itÐhave had a great in¯uence on us and inspired us to develop our approach. We would especially like to express our respect for Zev Naveh from the Israel Institute of Technology, Haifa, who developed many of the ideas on which we rely. His constructive comments and constant support give us the strength to further elaborate our ideas. Thanks also to the reviewers for their critical remarks and to Janine Perron for putting the ®nishing touches on our manuscript. References Antrop, M., 1998. Planning and landscape ecology. Landscape Ecological Papers, Centre for Landscape Research, Roskilde University, Vol. 11, pp. 29±59. Antrop, M., 2000. Background concepts for integrated landscape analysis. Agric. Ecosyst. Environ. 77, 17±28. Appleton, J., 1975. The Experience of Landscape. Wiley, London. Appleton, J., 1986. The role of the arts in landscape research. In: Penning-Rowsell, E., Lowenthal, D. (Eds.), Landscape Meanings and Values. Allen and Unwind, London, pp. 26±47. Bastian, O., Schreiber, K.-F., 1994. Analyse und oÈkologische Bewertung der Landschaft. Gustav Fischer, Jena, Stuttgart. Bender, B., 1993. LandscapeÐmeaning and action. In: B. Bender (Ed.), Landscape, Politics and Perspectives. Berg, Providence, Oxford, pp. 1±17. Bohm, D., Peat, F., 1987. Science, Order and Creativity: A Dramatic New Look at the Roots of Science and Life. New York. Bourassa, S.C., 1991. The Aesthetics of Landscape. Belhaven, London. Braune, W., Ebbinghaus, E.A., 1969. Althochdeutsches Lesebuch. Niemeyer, TuÈbingen. Bridgewater, P.B., Bridgewater, C., 1999. Cultural landscapeÐthe only way for sustainable living. In: Kovar, P. (Ed.), Nature and Culture in Landscape Ecology. Charles University, Carolinum Press, Prague, pp. 37±45. Capra, F., 1996. The Web of Life: A New Synthesis of Mind and Matter. Harper Collins, London. Checkland, P., 1986. Systems Thinking, Systems Practice. Wiley, Chichester. Clements, F.E., 1916. Plant Succession: An Analysis of the Development of Vegetation. Carnegie Institution of Washington, Washington.

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BaÈrbel Tress (1969) and Gunther Tress (1968) are landscape researchers trained in the natural sciences, social sciences and humanities. They hold Master's degrees in Geography and German from the University of Heidelberg, Germany, and European Doctorates in Landscape Research from the University of Roskilde, Denmark. Both served as assistant professors at the Centre for Landscape Research at the University of Roskilde within the interdisciplinary research initiative ``Value, Landscape and Biodiversity'' from 1999 to 2001. At present, they work at Alterra Green World Research in Wageningen, The Netherlands, and deal with transdisciplinary approaches to bridge the humanities, social sciences, arts, and natural sciences. Their fields of expertise in landscape research include inter- and transdisciplinarity, communication and information technology, the human±environment relationship, scenarios and future-oriented studies, systems theory, holism, organic agriculture, and tourism and recreation.