Landscape and Principles in: Landscape Ecology

Forman, R., Godron, M., Landscape and Principles in: Landscape Ecology, New York, 1986, John Wiley and Sons. by BART PLUYM

The text in question is actually the introduction of a book on landscape ecology. It can be read as a synthesis and guideline for the rest of the book, focussing mainly on :
the conceptual framework of landscape ecology;
putting forward a number of principles concerning landscape structure, landscape function and landscape change
the description of the state of the art of landscape ecology, by relating it to other disciplines and by putting it in an international perspective.

The first two parts of the chapter are dedicated to delineating the concept of landscape that is used by landscape ecologists. Given the fact that perspectives on landscape are diverse and multiple, a selective reading is given of the meaning of landscape in a few areas. Several aspects of the artist's approach are relevant for the understanding of landscape ecology: the diversity of landscapes that is presented in landscape paintings, the field of view that is generally similar to what the eye can perceive and the fact that the subject of landscape paintings normally include human and non-human elements. Landscape ecology though is only about the land and not about the water. The meaning of landscape in landscape ecology to a certain extend also has an affinity with the way the word is used by historians to indicate relatively extensive land areas where battles took place or where food was grown, settlements were built, .... But the concept of landscape that is used in landscape ecology finds its main source of inspiration in geography and ecology. Geography uses a concept of landscape that essentially focusses on the dynamic relation between natural landforms and human cultural groups. Landscape ecology distances is itself also in this sense from ecology: whereas ecology over the last few decades has focused on the relationships between plants, animals, water, ... within relatively homogeneous spatial units, landscape ecology focusses on the relationship between spatial units.

So what then makes a landscape from an ecological perspective? According to the authors five characteristics can be discerned across ecological landscapes: (1) a cluster of (visibly discernible) ecosystem types, (2) the 'flows' among the ecosystems of a cluster, (3) the geomorphology and climate, (4) a set of disturbance regimes1 and (5) a certain variation in the number of ecosystems within a cluster. These observations form the heart of the ecological landscape concept, an ecological landscape being defined by the authors as “a heterogeneous land area composed of a cluster of interacting ecosystems that is repeated in similar form throughout. Landscapes vary in size down to a few kilometers in diameter.” Three characteristics of the landscape form the focus of landscape ecology: (1) the structure of the landscape or the spatial relations among the distinctive elements, (2) the way the landscape functions or the interactions among the spatial elements and (3) landscape change or the alteration in the structure and function of the ecological mosaic over time. Landscape ecology studies both the principles concerning these characteristics of landscapes, but also the way they can be used in the formulation and solving of problems.

In the third part of the text the authors conceptualise a number of landscape elements, give a very brief summary of the different chapters in the book and formulate seven statements as principles regarding landscapes that together form an emerging theory of landscape ecology. According to this summary a large part of the book is about the fundamental structure of landscapes: all landscapes, despite their extreme diversity, are entirely made up by a number of patches, corridors or strips and a background matrix. The degree of contrast and the level and type of heterogeneity are also key characteristics of the landscape structure. The book also gives a lot of attention to the changing of landscapes according to natural and human influences and to the functioning of landscapes by looking at the flows of energy, materials and species between landscape elements. In the final two chapters some concepts for landscape applications are introduced.

The seven statements or principles are difficult to summarize without entirely copying what is already written. These principles can be interpreted as a “laws” concerning the structure, the functioning and the changing of landscapes. They bring forward – physical – relations between such things as the heterogeneity of a landscape and the abundance of rare interior species, the flows of energy and biomass across boundaries and the heterogeneity of a landscape, ...
The final part of the text is an overview of forefathers, forerunners and contemporary authors of landscape ecology. They are to be found in geography and ecology, but also in other related disciplines. It ends with a short reading of the state of the art from an international perspective.

1That is the intensity and frequency with which certain types of events cause significant change in the normal pattern of the ecological system.