As noted in the introduction to this chapter, forest landscape ecology deals with large spatial extents with a spatial resolution that is generally much coarser than the individual trees or stands that are more familiar to practitioners. Changes in the forest landscape over these large spatial scales often take place only over long periods of time, and these slow dynamics can only be observed through sampling at relatively infrequent intervals. At the same time, our observational perspective is comparatively fine-grained. We observe daily, seasonal, and interannual changes in trees and stands that might be significant with respect to larger-scale changes, or might only be high-frequency "noise" (i.e., insignificant variation).
With scale so central to forest landscape ecology, misunderstanding of the importance of scale or a failure to incorporate principles of scale in modeling of forest landscapes is likely to create barriers to widespread use of forest landscape ecological models. Conversely, understanding of the importance of scale and disciplined treatment of scale could both provide potential solutions.
By and large, principles of scale are not having a positive impact on the application of landscape ecology to forest management. This assessment is based on our combined experience with principles of scale in ecological, landscape, and forest landscape modeling, and observations of their use in forest management. Others also have discussed how understanding the concepts of scale is important to forest landscape ecology and other applications of landscape ecology (e.g., Allen et al. 1984; Bissonette 1997). Forest resource managers are increasingly aware of the importance of scale as modern forest management is moving toward forest landscape management. Forest landscape models that are sensitive to issues of scale, and particularly to large and multiple scales, have been and are being developed with application in forest management as a primary goal. However, we believe that the full richness of the literature on the importance of scale in ecology has not been exploited in the development of models, and that an understanding of ecological scale is not informing the practice of forest landscape management.
This occurs for a variety of reasons. First and foremost, many practitioners simply do not see the relevance of concepts of scale beyond the idea that forested landscapes involve a large spatial extent. If their understanding of landscape ecology is limited to the notion that landscape ecology is simply the ecology of large areas or that landscapes are nothing more than large areas, they may feel they know all that they need to know about scale. Thus, the failure of landscape ecolo-gists to emphasize aspects other than large spatial extents and to counter that bias may have created a barrier to practitioners pursuing a deeper understanding of scale.
Even practitioners and landscape scientists who have moved beyond that barrier may encounter additional barriers to understanding and incorporating the concepts of scale into modeling and practice. These include the possibilities that:
• There has been too little discussion of scale in ecology.
• The discussions of scale that have taken place may not have been sufficiently clear.
• The existing theory and principles of ecological scale may be too esoteric.
• Too much attention may have been placed on multiple scales rather than on the appropriate scale.
• Too little attention has been devoted to the defining principles of landscape ecology.
• There has been too little synthesis of our understanding of ecological scale.
• It is simply too soon for the science of ecological scales to significantly affect landscape management.
In the remainder of this section, we briefly address each of these issues.
2.5.1. Have We Discussed Enough about Scale?
Yes and no. Yes, because there has been much discussion of ecological scale in journal articles and books going back at least 20 years (e.g., O'Neill and King 1998). No, because the more important question is whether all that talk has been clear and effective in communicating the importance of scale to decisionmakers, managers, and other practitioners.
2.5.2. Has the Discussion of Scale Been Clear?
No, as a whole it has not been. There have been good discussions and explanations of the importance of scale in ecology (e.g., Turner et al. 1989), and individual presentations to potential users of this knowledge may have clearly and logically presented definitions of the concepts. However, the body of literature on scale often appears contradictory because different authors have investigated different problems, scales, or contexts without making these differences clear. This situation can generate confusion for individuals who are investigating how scale might influence an application. Perhaps more importantly, different individuals may develop different understandings of scale depending on which portion of the literature they sampled. Differences in understanding can lead to misunderstandings and confusion. The imprecise and inconsistent use of "scale" and "level" (as in the phrase "level of organization") is an example of one cause of confusion (Allen 1998; Allen and Hoekstra 1990; King 1997, 2005).
2.5.3. Has the Theory of Scale in Ecology Been too Esoteric?
Yes, at least in part. There are certainly commonsense aspects of scale that have influenced or are influencing forest modeling and management. One example is that large-scale systems such as forested landscapes require observations over large spatial extents and long time periods, and the scales of observation and management are increasingly being matched to the scale of the system. Similarly, there is an increasing recognition that the forest systems being managed encompass multiple scales, and new management approaches are addressing those different scales. There have also been largely theoretical discussions of scale explicitly targeted at an audience capable of applying this knowledge (e.g., Allen et al. 1984; King 1997). However, other aspects of the theory, including elements with rich potential insights on how to understand and manage large, multiscale systems, have tended to be couched in terms of unfamiliar abstractions and theoretical or mathematical terminology (O'Neill et al. 1989; Rosen 1989). The target audience for these presentations has been other scale researchers, which is fine so far as it goes, but the esoteric nature of these presentations, which comprise a sizable portion of the literature on scale in ecology, makes them unsuitable for practitioners. The differences in the language and style of presentation between researcher and practitioner audiences have been, in part, responsible for the limited influence of the discussion of scale in applied forest management. Some parts of the message are getting through; others are not.
2.5.4. Has There Been too Much Focus on Multiple Scales?
Yes. One of the recommendations to come from the consideration of scale in ecology has been a call for observations and studies at multiple scales. This is scientifically appropriate, but incomplete. It is certainly true that forested landscapes span a wide range of observational scales and involve processes operating at many different scales. It is also true that observations and studies at multiple scales will help determine how different processes operating at different scales are ultimately expressed at the scale of the forested landscape. But lost in this focus on multiple scales has been the equally fundamental message that there may be a single scale of observation, or a small set of scales, that is most appropriate to the specific management problem faced by a practitioner. If one has the objective of management of a forest at a given spatial extent for a given period of time, the theory of scale in ecology argues for finding the scale of observation most appropriate to that objective. It does not argue for, in fact argues against, looking at all scales encompassed by the scale of the management objective.
The principle of the appropriate scale for observing and understanding ecological systems draws heavily on hierarchy theory (Allen et al. 1984; King 1997, O'Neill 1989; Urban et al. 1987) and argues in favor of a three-scale approach. Hierarchy theory asserts that the focal level L of a system is the level of observable dynamics chosen by the investigator, and in the context of this chapter, is determined by the management objective. A mechanistic explanation of the dynamics at this level is found at the next lower level of organization L-1. However, level L occurs within the context of the next higher level L+1. This higher-level organization simultaneously bounds and is a consequence of focal level L, and both the constraints on the dynamics of that focal level and the significance or results of those dynamics can be found by examining the next higher level L+1. Allen et al. (1984) and King
(1997) and the references cited therein provide further details. Briefly, a three-level approach to nested, hierarchically organized ecological systems implies a corresponding three-scale approach to observing and understanding these ecological systems. The power of this approach lies in its emphasis on identifying the correct focal scale for a given management objective and the scales above and below that scale to discern the context and mechanisms (respectively) that govern that scale. It is this emphasis that has been lost in or obscured by the broader message that multiple scales are at work in any landscape.
A combination of hierarchy theory with the theory of scale can provide guidance on how to find the appropriate scales for a stated objective or application. This example illustrates how a richer understanding of scale can benefit applied forest landscape ecology. The consideration of scale in landscape ecology should be more nuanced than a simplistic recommendation to address only large scales or multiple scales. Such a message can be misinterpreted as a call for the study of multiple, arbitrarily selected scales even if those scales range from small to large. The arbitrary interpretation of multiple scales multiplies the problems for decisionmakers and managers, who are being asked to obtain scientifically sound observations and understanding at many different scales rather than at the most appropriate scale for their problem. The limited resources available to most practitioners would be better applied to identifying, observing, and understanding the most appropriate scale or limited number of scales for their management objectives.
Of course studies at multiple scales are needed to provide guidance for identifying the appropriate scales. Such studies might be required in circumstances in which theory provides uncertain or ambiguous guidance. Studies at multiple scales are also required in the determination of scaling rules or functions (King 1991; Milne 1997; Schneider 1994) that are used to translate information and observations across scales—for example, from the scales empirically accessible by field studies to larger scales of management objectives. In each case, there are uses for a fuller consideration of the importance of scale in landscape ecology.
2.5.5. Has There Been too Little Attention to the Defining Principles of Landscape Ecology?
Yes. Although this is not strictly an issue of scale, it is related to scale. Landscape ecology is a subdiscipline of ecology that focuses on understanding how spatial patterns and structures influence ecological processes (Turner 1989). It is true that most landscape ecology deals with spatial extents measured in thousands of hectares, but that tendency is historical and secondary, not a defining characteristic. The focus on how considerations of scale might help address a large spatial extent that encompasses processes at many different temporal and spatial scales has diverted attention from a consideration of how issues of scale might affect our understanding of spatial patterns and their influence on processes. Accordingly, the attention to scale, in the narrow sense of "large spatial scale," has detracted from the application of landscape ecology to forest management.
2.5.6. Has There Been Sufficient Synthesis?
No. The large and diverse literature on scale in ecology has not been sufficiently reviewed and synthesized from a scientific perspective. There has been even less effort devoted to synthesizing this knowledge from the perspective of potential application and to addressing problems using the language and examples familiar to the potential users of the knowledge. This lack of a useful and familiar synthesis has undoubtedly contributed to the limited application of considerations of scale and forest landscape ecology to forest management.
2.5.7. Perhaps It's too Early?
Perhaps. Intensive investigations of scale in ecology and the inevitable debates that have ensued go back more than 20 years. After that much time, one might hope for a more obvious influence of applications of scale in forest management and elsewhere than is currently apparent. The heightened awareness and understanding of issues of ecological scale in the scientific community has in fact influenced forest management to some degree; that is, the scientific deliberations on the challenges of large-scale ecological applications that influenced the growth of landscape ecology are gradually being transferred into applications. Today's discussions of forest management and ecological applications are different from those that occurred prior to the growth of landscape ecology and its considerations of scale. We suspect that the consideration of larger scales in modern forest management was driven primarily by the advent of satellite-based remote sensing and the accompanying changes in visual perspective, and that the emergence of landscape ecology was simultaneously influenced by these technological changes. But larger-scale applications and landscape ecology have grown together, have had positive influences on one another, and will likely continue to do so. Researchers and practitioners increasingly share their language, concepts, and understanding. The influence of science on practice undoubtedly requires more time to be fully realized. We may simply be anxious to see more impact and influence than the natural time scales of the feedback process permit. Nevertheless, the apparent influence has been patchy. Greater attention to the process of knowledge transfer to promote appropriate use of an understanding of scale in landscape modeling and forest management is called for.
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