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Library of Congress Cataloging‑in‑Publication Data
Names: Lopez, Ricardo D., author. | Frohn, Robert C. Remote sensing for landscape ecology.
Title: Remote sensing for landscape ecology : monitoring, modeling, and assessment of ecosystems / Ricardo D. Lopez.
Description: Second edition. | Boca Raton : CRC Press, [2017] | Previous edition: Remote sensing for landscape ecology : new metric indicators for monitoring, modeling, and assessment of ecosystems / Robert C. Frohn (Boca Raton : Lewis Publishers, 1998). | Includes bibliographical references and index.
Identifiers: LCCN 2017006901 | ISBN 9781498754361 (Hardback : acid-free paper)
Subjects: LCSH: Landscape ecology--Remote sensing. | Geographic information systems.
LC record available at https://lccn.loc.gov/2017006901
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This book is dedicated to the influential people in my life, especially to my wife Debra, for her unwavering energy, positivity, and love; to my mother Lynn, who always encouraged my imagination and creativity; and to my father Ricardo Carlos, who demonstrated how enjoying one’s work leads to lifelong fulfillment. I also dedicate this work to the many hardworking employees of the United States Environmental Protection Agency for their persistent pursuit of sound science, environmental justice, and public service.
Ricardo D. Lopez
To the memory of Robert C. Frohn, author of the first edition. This book is your continuing legacy.
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5.2.4
Preface
The broad goal of this book builds upon the first edition by elucidating and demonstrating landscape metrics and indicators that show responses to characteristic variations in remotely sensed ecological information. To achieve this goal, it is necessary to go beyond the first edition of this book and meet the multiple objectives that are a typical part of all landscape ecological projects. These are, in the twenty-first century, a characteristic expectation and need of society, and thus decision makers in a variety of realms. In addition to developing landscape metrics that are sensitive to change in patch characteristics, such as configuration and complexity, a thorough understanding of the environmental gradients of change that are of relevance to users’ decision-making needs or goals must precede the design of a project. The development of landscape metrics and indicators that are predictable with regard to changes in the biophysical characteristics of the environment as well as the spatial and temporal resolution of data used are among the key objectives of this book. To accomplish these goals, the linkages between ecosystem functions of interest and information provided by remote sensing data, as well as any limitations of either of these elements, are necessary to better understand in order to establish ecological significance, statistical significance, and relevance to communities and decision makers.
The metrics and indicators developed in this book are practical in nature, as well as quantitative; a major addition to this edition of the book is the practicality of the approaches taken, with specific examples and outcomes. Although the first edition advocated powerfully for the use of specific metrics for theoretical reasons, which are sound and very important to consider, there is an emerging paradigm within community planning, natural resource management, ecological restoration, and conservation as a whole that demands the inclusion of landscape scale analyses within all societal development, which has become well established and institutional in some cases during the past two decades and since the completion of the first edition. The metrics outlined in this edition are based upon these societal demands, and utilize a balance of scientific and geostatistical approaches necessary to ensure fidelity under a number circumstances, driven by geography, biophysical conditions, and data availability. All of the landscape metrics and indicators described in this edition are provided as diverse examples for application and modification, all founded in sound science as well as the user’s specific decision-making needs or goals.
This edition goes far beyond applying theory to the four project case studies by addressing a broad range of challenging project needs encountered in today’s sophisticated atmosphere of melded scientific and societal approaches for broad-scale landscape ecology, which naturally impinge
upon both the spatial and temporal gradients of all of the regions described. Briefly introducing the needs addressed and the geographic areas covered by this edition are the landscape ecological metrics and use of diverse outputs of remote sensing in the entire Laurentian Great Lakes (United States and Canada) Watershed; landscape ecological metrics and indicators of water quality derived from both remote sensing and field information in the Ozark Mountains (Missouri and Arkansas) Watershed; a landscape ecological focus on sea level rise in both coastal California and coastal North Carolina areas as it encroaches on the landscape in the coming century; and landscape hydrologic conditions and modeling in the Missouri River and Mississippi River Watersheds. All four geographies presented in this edition utilize wellestablished landscape metric fundamentals and include novel methods for practical application, which demonstrate the capability of a host of metrics for distinguishing among land cover types and landscape changes.
The book provides important new outcomes from research and development on the integration of remote sensing, geographic information systems, and landscape ecology metrics for modeling, monitoring, and assessment of ecosystems at a variety of scales. The long-term value of such research and development of applications has been incompletely realized; however, as society continues to employ these technologies into the future and methods continue to be developed to improve understanding of the world in which we live, a better awareness of “systems thinking,” especially for developing predictive models, can be utilized to shape decisions, and those decisions can be realized in demonstrable ways that serve society. Because the book is concerned with the development and application of landscape ecology metrics, it may be misunderstood that the metrics and examples used are exclusive of other work in this extremely large field of landscape ecology; this is not the case. The work described in this edition is meant to address a wide spectrum of similar work, and it is not the authors’ intention to suggest that other studies are without merit or not demonstrative in their own right, but rather that the examples provided in this edition are emblematic of the precepts and concepts embodied within the current discipline of applied landscape ecology. The authors are indebted to the researchers of past studies in landscape ecology, especially those who have been devoted to the development of the numerous array of landscape ecology metrics and indicators as a whole.
Acknowledgments
This book integrates and synthesizes a complex topic, utilizing a host of methods and approaches for utilizing remote sensing and other information for landscape ecological analyses. As such, a number of fine people played key roles in the development of these techniques, including Lee Bice, Don Ebert, Curt Edmonds, Ed Evanson, Brenda Groskinsky, Michael Jackson, Maliha Nash, Kamal Qaiser, Caroline Torkildson, Rick Van Remortel, Larry Woods, and Yongping Yuan. For their hard work and skills, the author is forever grateful.
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Author
Ricardo “Ric” D. Lopez, PhD, has been a leader in the field of landscape ecology over the past three decades. During his tenure in academia and public service with the Ohio Environmental Protection Agency, the U.S. Environmental Protection Agency, and the U.S. Forest Service, he has led in the geographically diverse applications of remote sensing and field-based approaches for geospatial analyses, as applied to both theoretical and applied environmental topics. This body of work includes the monitoring and assessing of terrestrial, aquatic, and transitional ecosystems; invasive plant species; multiscale indicators of sustainability; and solutions to risk-based landscape ecology issues. A native of California, Dr. Lopez has spent much of his life exploring, appreciating, and writing about the diverse aspects of complex landscapes, from the tropics to temperate regions, bringing his expertise as a landscape ecologist to bear on specific local, regional, and global environmental issues. He earned a BS in Ecology, Behavior, and Evolution at the University of California, San Diego, and master’s and doctoral degrees in Environmental Science at The Ohio State University, with an emphasis in landscape ecology and wetland ecology. Dr. Lopez is currently the Director of the U.S. Forest Service’s Pacific Southwest Research Station—Institute of Pacific Islands Forestry in Hilo, Hawai‘i.
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1 Introduction
1.1 New Challenges for the Landscape Sciences
This book expands on the first edition (Frohn 1997) by focusing on the specific applications of the fragmentation and patch complexity metrics that are often utilized in landscape ecology, as derived from remote sensing data. To that end, the reader will find that their project work shares a number of similarities with the examples in this book, albeit perhaps in different geographies or other circumstances. Those “other projects” that are familiar to the reader will be informed by the processes used and the outcomes generated from the presented projects in this book, which integrate well with a large number of disciplines (from biology to engineering to hydrology), all of which collectively define the collective of disciplines (and individuals) who are the members of an excellent and diverse landscape sciences team. Numerous quantitative measurements of landscape pattern have been used in the field of landscape ecology (e.g., as outlined by Krummel et al. 1987 and O’Neill et al. 1988) several decades ago, which has served as a basis for quite a bit of landscape ecological work since then. These measurements, often called metrics or indicators, have been used to link ecological and environmental processes with patterns found within the larger geographic matrix, commonly referred to as the landscape (Forman 1995). The applied use of metrics often requires the practical use of existing data and these fundamental metrics are often simplified or modified from three fundamental metric types (i.e., dominance, contagion, and fractal dimension), and derivations thereof, to match the biophysical environmental conditions, ecosystem processes and characteristics, or the decision-making goals of the users in a particular geography. The specific application of numerous landscape metrics and indicators are applied and discussed in detail in Chapters 4 and 5. Various landscape ecology metrics have been used to quantify aspects of spatial patterns, and to correlate them with actual ecological processes (e.g., O’Neill et al. 1988; Turner and Gardner 1991; Baker and Cai 1992; McGarigal and Marks et al. 1994; Riitters et al. 1995). In particular, spatial pattern metrics that are related to contagion and dominance (based on information theory) and fractal dimension (based on fractal geometry) have been used
extensively throughout the landscape ecology community (e.g., Krummel et al. 1987; O’Neill et al. 1988; Turner and Gardner 1991; Milne 1991; Wickham and Riitters 1995), and indeed serve as the basis of a host of developed metrics since these earlier days of contemporary landscape sciences. These three metric types have been extensively utilized in various modifications for implementation of watershed integrity indicators; landscape stability and resilience indicators; and biotic integrity and diversity indicators, as demonstrated in the latter chapters of this book. Several tests of these metrics and indicators have also occurred within the remote sensing community (e.g., Wickham and Riitters 1995; Wickham et al. 1996; O’Neill et al. 1996; Fenga and Liu 2015).
Dominance metrics have been used as a landscape diversity measure by determining the equality of the proportion of land cover types across a particular landscape (O’Neill et al. 1988). High dominance indicates that one or more land cover types are covering the landscape. Low dominance indicates that land cover types have nearly equal proportions. However, dominance does not necessarily indicate diversity of the landscape. For example, a landscape with two land cover types with 50% proportion will have the same dominance value as one with 10 land cover types with 10% proportion. Thus, the same arguments that apply to species diversity indexes apply to the dominance landscape metric of diversity. Also, the dominance metric does not actually give a quantitative measurement of landscape pattern, although it has been referred to as a spatial metric. This book demonstrates the use of the dominance landscape metrics (e.g., the use of the Shannon–Wiener Index and Simpson’s Index) within this context and understanding of the limitations, and within the context of other ecological metrics, such as contagion and fractal dimension metrics—the combined application of these three types of metrics, and an understanding of their uses and limitations, leads to the concept of ecological significance of landscape metrics.
Contagion metrics have been used in ecosystem analyses to quantify the amount of clumping or fragmentation of patches on a landscape (O’Neill et al. 1988). They have been utilized to relate the effects of contagion patterns on ecosystem processes such as habitat fragmentation, vegetation dispersal, and animal movements (e.g., Turner and Ruscher 1988; Turner 1989, 1990a, 1990b; Graham et al. 1991; Gustafson and Parker 1992; Li and Reynolds 1993; USEPA 1994, 1996). Fractal dimension metrics have been used in ecosystem analysis to quantify the complexity of patch shapes on a landscape (e.g., Krummel et al. 1987; O’Neill et al. 1988; De Cola 1989; Lam 1990); all of these metric categories have also been used to measure the degree of human disturbance on the landscape. The underlying theory of these metrics is that natural boundaries, such as those for vegetation, have relatively more complex shapes than those that are a result of human activity, such as agricultural fields. As human disturbance increases, the fractal dimension of the landscape decreases (e.g., Krummel et al. 1987; O’Neill et al. 1988; Turner
and Ruscher 1988; De Cola 1989). The contagion and fractal dimension metrics have been evaluated for their sensitivity to variations in remote sensing data and raster data structures (e.g., Kalkhan 2007) and findings are that orientation, shape, and resolution of remote sensing data elements can lead to more or less usable information, relative to ecological processes on the ground. These metrics were originally developed to focus attention toward quantification of landscape pattern and to encourage the development and application of new or improved metrics in ecosystem analysis (O’Neill 1996; personal communication in Frohn 1997).
The utility of any landscape metric is dependent on its maintaining a consistent response to observed phenomena. This does not occur when the fundamental assumptions applied in its formulation are violated. Even in cases where the use of a contagion or a fractal dimension metric may be appropriate, there are a number of characteristics that affect the quality of map and image data, including spatial resolution, geometric registration, and level of classification. In order for a landscape metric to be effective it should also be relatively insensitive to arbitrary sampling characteristics while being very sensitive to the specific spatial patterns. Since remote sensing and other landscape data are captured in a wide variety of geometric representations, landscape metrics must be formulated to compensate for specific sampling geometries in order to facilitate comparison and integration across scales and among different studies.
In addition to technical remote sensing challenges, a critical additional consideration has emerged in the past decade that is relevant to contemporary and future applications of remote sensing for landscape ecology. These considerations drive not only the ultimate use of the outputs but also consideration of accuracy and precision in data incorporation of the social dimensions of the landscape. Evidence of these changes are the incorporation of the terms sustainability and ecosystem services into the decision-making goals and objectives of many landscape ecology projects and research, particularly in the past decade. The concepts of sustainability are not new; however, their current incarnation that unifies social and ecological perspectives of nature provides a challenging new goal for all landscape ecologists to quantify ecosystems (e.g., identification and characterization), their condition (e.g., ecological functions), and their relationship(s) with society (e.g., ecosystem services) (Reid et al. 2010). From the most general concept of sustainability comes a broad view of environmental and ecosystem management issues, which offer approaches for going beyond solely the technological solutions to environmental problems by integrating social participation and policy dialogue with ecological inventorying, monitoring, and assessment activities.
Among the many emerging critical and future threats to the sustainability of ecosystems are soil loss and degradation; water scarcity; and the loss of biological diversity (Running et al. 2004), regardless of the sociological contexts. The perceptions of these environmental problems vary tremendously,
depending upon a number of socioecological factors. If remote sensing data, and indeed all associated geospatial information, is to have an impact on the users in these areas, the information produced needs to be compelling, accurate, and easily accessible to the user (i.e., must have high impact and availability). Some argue for an approach that addresses this complexity as a “multilevel stakeholder approach to sustainable land management,” for finding feasible, acceptable, viable, and ecologically sound solutions at local scales. As explored in-depth in Chapter 6, a number of international programs and bilateral cooperation projects have taken this perspective and started using a sustainable land management approach, such as in the case of the United Nations Capital Development Fund. A sustainability paradigm such as sustainable land management requires that a technology follow some fundamental principles: (1) ecological protection, (2) social acceptance, (3) economic productivity, (4) economic viability, and (5) risk reduction (UN 2012). Accordingly, a technological approach to resource management that is sustainable would have to be developed using criteria for a particular and locally relevant land use, and would likely not be applicable everywhere. This method encourages the full exploration and inclusion of the economic, social, institutional, political, and ecological dimensions of the community/ geography in question. Global environmental professionals have suggested the efficacy of this approach of tying environmental science, technology, and society by explicitly linking research on global environmental change with sustainable development (Reid et al. 2010), which would necessitate an increased use of remote sensing and geospatial analysis for monitoring ecosystem conditions, and also for measuring feedback loops between environmental conditions and societal values and activities.
1.2 Goals and Objectives of This Book
The principal goals of this book are to thoroughly outline the various advantages and limitations of utilizing remote sensing data for landscape ecology, and to provide practical examples of the use of landscape metrics within the context of the aforementioned advantages and challenges with a full discussion of the many considerations that must be made when selecting remote sensing data types, exploring project designs, and utilizing the outputs of projects. In the first edition of this book, the author approached this challenge from a purely quantitative perspective, focusing mainly on the specific methods that would ensure greater certainty in the technical/theoretical applications of remote sensing data. This book expands this approach by soberly looking at the current state of the art, in terms of the remote sensing data utilized for developing landscape metrics and indicators as utilized in the field, tying the technological and scientific elements to practical
management goals and perspectives, which drive today’s needs in society. Specific examples go far beyond the theoretical and utilize remote sensing data in a variety of key geographies, with user needs that must be met, and have been specifically selected to demonstrate techniques for expanding and building upon the earlier edition’s information. Each of the examples given are actively used by end users and decision makers, making them an excellent demonstration of both the theoretical and applied uses of remote sensing and landscape ecology. This approach is not intended to completely overcome the uncertainties described above in the challenges of Section 1.1, rather they are meant to demonstrate the approaches for balancing uncertainty with project needs and professional approaches, which the reader is no doubt likely to experience in present or future circumstances. In this book, three specific concepts and approaches are used to overcome these challenges, which were outlined previously:
1. The concept of ecological significance is key to understanding trends and multiple streams of data with ecological theory as a basis of understanding those trends and data.
2. The concept and approach of trajectory analysis is important for interpreting multiple streams of data, including both the qualitative and quantitative, leading to further inquiry and discovery of trends.
3. The concept and approach of hypothesis generation (without a fear of endless analysis) in a particular geography or ecosystem type, which enables the use of data that is imperfect, within a controlled analytical environment, where assumptions are stated and utilized to guide user’s interpretation, decision making, and further generation of hypotheses and focused work (perhaps at another scale or a subsetted area of analyses).
This book also utilizes these three complementary concepts/approaches, which were initially explored in the first edition, building further upon what has been learned in the past two decades of landscape ecological applications. The expansive approach taken in this edition recognizes the tremendous progress made since the first edition, and the need to continue that progress in the discipline of landscape ecology as a whole, despite substantial uncertainty that is intrinsically a part of environmental data collected from a distance, i.e., remote sensing of the environment, while providing some fundamental concepts and approaches for utilizing these constantly improving sources of data. A much more expansive approach in this edition provides the reader with additional tools, techniques, and perspectives to comparatively explore the approaches taken under the challenging circumstances of uncertainty to further the goals of landscape ecologists and remote sensing scientists/practitioners, specifically as it pertains to landscape monitoring, landscape modeling, and the assessment of ecosystem functions.
In general, the goals and objectives of this book are met by carrying out a series of tasks. These tasks include the following:
• A contemporary overview of landscape ecology metrics for the monitoring and assessment of landscape change through application and an improved understanding of ecosystems from that perspective.
• A contemporary evaluation of landscape metric types (dominance, contagion, and fractal dimension) on a conceptual basis, and through specific applications.
• A comparison of landscape metrics using real-world data, conditions, and circumstances for various gradients of change, including both the biophysical and the societal considerations of the landscapes involved.
• An analysis of the strengths, weaknesses, opportunities, and limitations for utilizing each of the metrics explored, and the implications for future work in the field of remote sensing for landscape ecology.
1.3 Utilizing This Book to Its Fullest Benefit
This book is intentionally written for the full diversity of environmental and resource professionals at the broad-level and sub-fields of engineering, ecology, resource management, climate sciences, and policy development at the local, state, regional, national, and global scales. This book is certainly useful as a reference and handbook for readers increasing their understanding of broad scale landscape ecology work that involves the direct use of remote sensing data, and also provides a wide variety of geospatial data outputs, all of which provide a full range of examples to guide readers’ project work. Results and information in the several applied examples in this book contain some key nuggets of information that come from experience and application, many of which address the important linkages that are not always apparent in every project, spanning resource parameters, a variety of scales, and decision making processes. Such use of technology and science to serve the needs of broad scale issues can inform national and international policies related to, for example, restoration; clean water; climate change; human safety, health, and well-being; and sustainable development (Doyle and Drew 2008), with direct relevance to international commissions, conventions, protocols, and agreements that require compiling information from community- and place-based analyses, allowing for broad scale application of the relevant elements from fine-scale needs and decisions. A worthy example, discussed in detail in Chapter 3 with applications in Chapter 4, is the ongoing work in the transboundary ecosystem of the Laurentian Great Lakes, where Canada and the United States have successfully collaborated to monitor and assess
the ecological functions and services of the entire Great Lakes Ecosystem, known as the Great Lakes Restoration Initiative, with tremendous strides in recent and novel research and restoration. The initiative was initially funded in 2010 and is now reaching nearly $2 billion through the Fiscal Year 2015 President’s Budget. This particular example provides a specific vision for future successful linkages between the applied work of remote sensing specialists and landscape ecologists, with an in-depth presentation of this specific transboundary solution to evaluating and monitoring massive landscapes; in this case, the entirety of the Great Lakes Watersheds. This in-depth example is followed by several other important landscape projects with additional intricacies and subtleties of analysis, which similarly link fine-scale information and needs to broad-scale understanding of environmental conditions, each serving decision makers and communities well.
This book uses the selected applied examples to highlight current remote sensing, geographic information systems, geostatistical, and modeling techniques to address the challenges you may encounter now, or in the future, in your particular geography or professional circumstances. The techniques demonstrated in this book are selected to show the breadth of applications for a diversity of landscapes and ecosystem types, resource conditions, and societal dimensions that are encountered every day by practitioners.
Throughout the book, a number of Internet sites and other resources from the literature are noted for reference, which equip you as the reader with a tremendous amount of integrated information that provides you with timesaving and clear pathways toward the solution for specific challenges that you may encounter when utilizing remote sensing for landscape ecology. All of the methods and approaches outlined in this book provide both new users and seasoned professionals with practical tools for success in the ever-changing world of landscape sciences, which now requires, at least, a reasonable facility with possibilities for the use of remote sensing to communicate effectively with like-minded professions. The complexity of present-day situations presented to ecologists, particularly if the focus is beyond plot-based work, requires an agility of understanding, conceptualization/articulation of capabilities, design skills, and the knowledge of the steps needed to implement a landscape scale project (or at least an ability to direct others on a viable path), by providing the necessary detail and synthesis of numerous available/ potential approaches. This book was designed to provide several quality examples of successful and complex landscape ecology projects (Chapters 4 and 5), all of which have a number of the complexities mentioned above, so as to explain how you can develop a fully successful project with substantive outputs and outcomes under such circumstances. The approaches and methods described in this book should be read and analyzed by you, the reader, in such a way as to discover and extract similarities in your work, so as to recognize and translate the circumstances in the work described in this book into your own application of the same or similar technology, science, and societal parameters. To aid in this utilization for the contemporary
applications of the reader, several new aspects are included in this edition of the book.
1. A practical update of remote sensing data types and geospatial methods
2. Demonstrations of specific examples, which are project driven
3. Descriptions of any pitfalls of using ecological data at landscape scales, with solutions
4. Discernment of alternative techniques for a variety of practitioners
5. Inclusion of specific linkages between field-based and landscapebased remote sensing and ecological practices
6. Updated resources for practitioners
1.4 Significance of Landscape Ecology Research
It is important to realize, initially, that there is a theoretical basis for the two rich disciplines of landscape ecology and remote sensing, as well as the many allied sciences involved in the work we will discuss in this book. Ultimately, landscape metrics are employed to create quantitative measures of commonly observed spatial patterns found on a map or within a remote sensing image or data set. Just take a look at a map or image derived from remote sensing imagery, or within a data set associated with the map or image, and notice the multitude of patterns illuminated. If making a visual assessment of the map or an image, perhaps the landscape is full of rectangular geometric shapes, which may be indicative of agricultural fields. Or perhaps one finds an image that contains an array of adjacent circles, indicative of fields with center point irrigation systems. In other areas one may see a regular grid of intersecting lines, such as those often found in residential areas. One may notice in a scene that there are many elongated complex shapes such as those found in association with geologic formations. Or, there may be a series of thin elongated narrow strips with a more regular shape, indicative of geologically “folded” mountain ridges and valleys. One notices these similar patterns across the world, and indeed, all of these patterns are observable in each of the focal geographies described in later chapters, within the Great Lakes Basin, in the marine coastal areas of California and North Carolina, in the rolling Ozark Mountains of Missouri and Arkansas, and in the Midwestern large river systems of the United States. These commonly observed patterns help us as landscape ecologists understand common processes that may occur in different geographies without the need to completely “reinvent the wheel” in each new study area. Nonetheless, hypothesis testing is always needed to confirm that the characterization of the landscape is accurate, and that metrics are an accurate measure of ecological processes on the ground.
One may also notice the particular arrangement of patches across a landscape. Perhaps patches are fragmented into thousands of small forested wetland patches along a river bank, such as in the Midwestern Missouri River Basin. Or they may exist as large patches of forest with cleared areas where development has occurred, such as in the Ozark Mountains. Basically, when one views a satellite image she may notice or identify many elements that, when combined, characterize the physical aspects of the scene. These elements include tone or color, shadow, illumination, location, association, objects, and process. In addition, the observer may notice varying shapes and sizes of those elements, textures, and patterns. It is the quantification of these groups of elements into a measurable variable that creates what we refer to as a landscape metric. Thus, all of the patterns mentioned previously can be quantified and distinguished from one another through the use of landscape metrics, in an infinite variety of combinations. Quantifying these patterns is critically important for a number of reasons, not least of which is that images need to be described by an observer in such a way as to convey comparability and condition, if necessary—this is a communication need for all analysis outputs, but is most important for images and complex geospatial data sets that contain more information than can be humanly possible to process at one time. Consider the complex matrix of geology, soil, and geomorphology (e.g., ridges, sheer cliffs, and valleys) in the Ozark Mountains. How does one describe the shapes, patterns, and textures of this area in a few words? Landscape metrics can potentially quantify these spatial patterns in one or two variables. But, more importantly, the use of landscape metrics by researchers can facilitate the detection of patterns of change that are not readily visible to the human eye nor easily detectable by a human analyst, when utilizing the power of remote sensing and the expertise of remote sensing scientists and practitioners.
Another critical reason why landscape metrics are necessary is to better understand our surroundings in terms of those landscape patterns and ecological and environmental processes, and importantly, so these elements can be linked quantitatively. For these reasons, landscape ecology is indeed the study of the effects of landscape patterns and their changes on ecological processes, and the understanding of these relationships is the constant pursuit of those engaged in this discipline. By quantifying spatial patterns and their changes, landscape ecologists endeavor to quantify their effect on ecological processes, and thus we can study changes in habitat of a particular species or community of organisms and determine whether the habitat has become too fragmented for the species, or an entire biological community, to persist in a particular geographic location. With this fundamental approach understood, we can move forward to determine, for example, the complexity of shapes of a given habitat type (e.g., oak-dominated forests) or determine if certain organisms (e.g., black bear) may travel among locations, given certain impediments between various land cover types and the resources at the locations (i.e., accounting for distance or land cover types). All of these
ecological functions, and more, can be theoretically determined and applied from remote sensing data, provided we adequately integrate, test, and apply landscape ecological metrics and remote sensing approaches thoughtfully.
There are a number of aspects of the discipline of geography, particularly remote sensing and geographic information systems, where this book makes a significant contribution. One fundamental contribution is how the combination of both remote sensing and landscape ecology bridges the disciplines of ecology and geography. More specifically, the melding of methodologies and applications of remote sensing and landscape ecology brings knowledge concerning quantitative landscape processes to users of remote sensing and geographic information systems. Of course, remote sensing has long been used as a means for providing data for environmental studies; however, to date, the use of remote sensing technology to characterize landscape patterns and relate those patterns to ecological processes has not been entirely explored, relative to other more integrated disciplines that utilize technology, for example, and analogously, biomedical engineering.
There are a number of other contributions that this book can make to geography, particularly remote sensing and geographic information systems (GIS). First, relevant landscape ecological metrics could certainly be used to improve the classification of remote sensing data in a number of data sets. For instance, some of the landscape ecology work accomplished for this book allowed for the ability to characterize entire watershed basins, coastlines, and instream conditions. This gives notion to what has been referred to as a spatial signature of a given land cover type (Frohn 1997). By placing more emphasis on spatial pattern with landscape metrics for land cover classification or combining landscape metrics with spectral or other biological or biophysical information, classification products from remote sensing data can be greatly improved in this regard.
This book is special in that it also strongly emphasizes the practical uses of a number of classical spatial analysis methods within the context of specific societal needs and satisfies the need for practitioners to better determine and infer the biological and biophysical conditions within larger and larger landscapes, worldwide. The authors welcome the reader to consider the similarities, and perhaps the dissimilarities, between the context of the work outlined in this book with their own work context, to aid in developing their plans for metric selection, scale of work, structuring of projects, or other aspects of the outlined projects in Chapters 4 and 5.
1.5 Selection of Study Sites
In this edition, four relatively large extent geographic areas were chosen for the purposes of analysis and demonstration of landscape ecological methodologies
and the use of remote sensing to achieve the specific goals of each of the four areas. The four study areas were chosen to assist in these analytical and demonstration cases, specifically because each of the areas has unique biophysical and ecological conditions and gradients that can be characterized and discussed in detail. Although such specific areas may not coincide exactly with the particular focus areas in which you conduct your work, by exploring and understanding the remote sensing and landscape ecology approaches in each of the case study project areas, consideration of the circumstances of each will provide you with insight into most of the relevant issues that stakeholders, managers, and researchers encounter at multiple scales, in most cases. Both spatial and temporal gradients are included and analyzed in the four examples to better characterize the environmental conditions that exist; provide a look at how complex both spatial and temporal components and scale can be influential in determining project design and outcomes; and determine how the challenges of setting these limits can be informative in your project’s design. The key to understanding how the four case studies in this book integrate is to understand how scale and diversity of landscape elements, in addition to the constraints of the remote sensing data and technology, all weave together to address the key questions of decision makers.
The first of the four geographic locations selected is the Laurentian Great Lakes Watershed. This project case study demonstrates the role of landscape data in spatial and temporal ecosystems and general biophysical characterization of a very large and complex landscape. By identifying strategies for the assessments of the extent, composition, and landscape configuration of both upland and wetland elements across this vast area at a synoptic scale, the value of utilizing remote sensing to affect the evaluation of landscape ecological attributes is evaluated and demonstrated actively. The landscape metrics used are quantifiable measurements based on data that are spatially explicit and geographically referenced. In the context of watershed management, this case study can provide options for using landscape metrics, particularly in a dynamic societal context. Additionally, this study shows how relatively broad-scale use of metrics can be utilized for hypothesis generation, where remote sensing data can then be linked to field data for both validation and scaling. Ultimately, the integration of landscape scale metrics with ground-level ecological functions is critical to managing natural resources, and the work in the Great Lakes points us in that direction, which is then carried forward in later case studies.
The second selected geographic location is the California and North Carolina coastal regions of the United States. This project case study tackles a very pressing global environmental crisis, sea level rise along coastal regions of all marine coastlines of the planet, by utilizing remote sensing data and modeling of sea level data to characterize the influence on coastal landscapes, specifically low-lying areas that are typically marshy or swampy. The extent and the degree of the loss of these coastal regions is a very challenging
question for geographers, ecologists, engineers, and policy makers to address in the coming years. This study demonstrates the necessity for understanding and utilizing the trade-offs available to us all in terms of the precision of various models and landscape metrics, and the need for ecologically and societally significant information to meet pressing project goals. These concepts and challenges apply equally to many similar landscape ecological issues, such as changing temperature along elevational and latitudinal gradients, and changing precipitation along elevational and latitudinal gradients, which are both also driven to some degree by climate change.
The third of the four selected geographic locations is the Ozark Mountains, United States. This project case study is a truly groundbreaking watershed analysis that redeems the goals of remote sensing being used to characterize not only the physical nature of watersheds, but also the biophysical characteristics of the contributing areas outside of the channel, riparian areas, and also by utilizing these techniques to infer the water chemistry and water quality characteristics within the water flowing through these systems. Because the analyses are moderate in geographic extent, the impression may be left that this case study is not applicable to larger areas of the landscape, but upon consideration of the methods and approaches used, it can be seen how the methods and approaches presented can be applied to any number of areas, given similar data, across a vaster area if necessary. An important step forward in this case study, as compared to the Great Lakes work, is the use of specific ground-based field ecological data to calibrate the remote-sensing based models, from the headwaters of the White River, through a multitude of tributary streams, to the main stem of the White River, which ultimately feeds the Mississippi River and Gulf of Mexico. This work also incorporates the complexity of human population increases in the region, land cover changes, and utilizes spatiotemporal complexity to inform the use of remote sensing to model ecological conditions on the ground. As in other areas that you may be considering doing similar work, the selection of landscape metrics is key to answering the necessary and pressing issues of watershed and riparian configuration of agricultural, urbanization, changes in forestland cover, and the concomitant influences on surface water conditions.
The fourth and final geographic location selected is the Missouri River and Mississippi River Watersheds, with a special focus on the Kansas River (one of twenty-two tributaries analyzed). This project case study predicts major natural hazard impacts and floods, which affect the largest number of people worldwide, averaging 99 million people per year. This area has experienced unprecedented flooding in recent decades that have caused many fatalities, evacuations, and large financial losses. In addition, urbanization in these areas is on the increase, just as in similar areas around the world. Such urbanization generally increases the size and frequency of floods and may expose communities to increasing flood hazards that result in an increasing focus by planners and land managers on the role of urbanization in the prediction of flood levels and damage. Most of this work by planners is for
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might go over the horse’s head. But he came back safely, and at last brought the horse down to a walk.
“Whoa there, Charley Boy,” he said as soothingly as a panting breath would permit. “Good boy now! Keep quiet!” And then he managed to bring the horse to a standstill.
When the others came up Randy dismounted and all saw that the horse had received several deep scratches on the flank, and from these the blood was still flowing. Randy and Jack attempted to wipe the blood away, but the horse would not have this and acted as if he meant to “kick them into kingdom come,” as Andy expressed it. So then they let him alone.
“What became of the wildcat?” questioned Randy.
“It wasn’t a wildcat. It was a young mountain lion,” declared Jack. “Fred and I tried to get a shot at it, but it got away up the mountainside before we could get our guns around to taking aim.”
“Didn’t the mountain lion hit you at all, Randy?” questioned his brother anxiously.
“No, he missed me by a couple of inches,” was the reply “I saw him coming and I dodged. He went right over my shoulder and then struck the horse. Of course Charley Boy wouldn’t stand for that, and he swung around as if hit with a red-hot whip. That threw the mountain lion to the ground, and what happened to the animal after that I don’t know because I had my hands full with the horse.”
“Gee, I’m sorry we didn’t get a crack at that beast!” said Fred regretfully
“Well, there’s one thing sure,” returned Andy, and something of a grin showed on his face. “We know that there’s one kind of game around here. In fact, two kinds, if you’re going to count the fish.”
After the horse that had been attacked had been thoroughly subdued the boys continued on the trail around the lake. Now, however, they kept their guns handy, hoping they might get a sight of the mountain lion or some other game.
But nothing appeared and, having come to the point from which they had started, they climbed up the road leading to Sunset Trail. By this time the sun was descending behind the mountains to the westward and they thought it time to return to Gold Hill.
When they got back to the boarding house they found that Peter Garrish had been busy during their absence. Evidently the mine manager had called upon the colored man who kept the place, for Toby was no longer as affable as he had been on their first appearance.
“Very sorry to tell you,” he announced. “But I’m expecting some other miners in a day or two, so I’ll have to ask you all to give up your rooms and go elsewhere.”
“Have you told my father this, White?” demanded Randy.
“I ain’t seen your father. He didn’t even come back for his dinner.”
“That’s because he had to go away on an errand,” answered Andy. “He said he’d be back by supper time, and it’s almost that now You had better not try to do anything until you see him.”
“Well, I’ve got to have the rooms, that’s all there is to it,” answered Toby White, and started to shuffle off.
“I suppose Mr. Garrish put you up to this,” called Jack after him.
“That don’t make no difference—I’ve got to have them rooms,” muttered the colored man, and then went away
A little later Tom Rover appeared and the boys at once acquainted him with what Toby White had said. They had agreed to say nothing about the encounter with the mountain lion, fearing that Tom might keep them from going out camping as they had hoped to do.
“I expected something of that sort,” answered the twins’ father. “And after I had sent off my telegrams I had a talk with Terwilliger, the keeper of the store. He told me of a man who lives up on Sunset Trail just a short distance from here—a man named Corning. I went and saw this Corning, who used to run the Mary Casey mine. I made an arrangement to stop at Corning’s house provided we were put out here. Corning has his two old-maid sisters with him, and Terwilliger
says they are good cooks and good housekeepers, so I imagine we won’t miss anything by making a change.”
“But don’t you want to keep an eye on this place?” questioned Jack.
“Yes, I’m going to keep an eye on it, and in a way Garrish little expects. But I won’t be able to do much openly until I hear from Mr. Renton and two other stockholders named Parkhurst and Leeds. If I can get those three stockholders to act with me we’ll control a majority of the stock, and then we’ll be able to run things here to suit ourselves.”
“Did you hear anything at all from Billings?” asked Fred.
“Not a word. He wasn’t seen around Maporah nor at Allways, the next station. I am satisfied that he is either in hiding or else he’s met with foul play.”
The meal served to the Rovers that evening was a fairly good one, but it was plainly to be seen that Toby White was more than anxious to have them take their departure. Tom said but little to the colored man, fearing that the fellow was entirely under Garrish’s thumb.
“I don’t believe in staying where I’m not wanted,” he told Toby White. “I’ll settle with you right now and we’ll leave as soon as we can pack our things.”
“Sorry, Mr. Rover, very sorry,” said the colored man. “But you know how it is here—this place is leased to me by the mining company and I’ve got to keep my rooms for nothing but miners.”
“Yes, I know. And we’ll go.” And shortly after that the boys and Tom Rover took their departure.
It was not a long journey to Cal Corning’s place, a long, low log cabin containing eight rooms, all on the ground floor. Behind the cabin were half a dozen outbuildings, for Corning was the only man in that vicinity who kept any cattle.
“Well, I’ll say this is an improvement over Toby White’s place,” remarked Jack, when they were settling down in the three rooms
assigned to them. Two were of fair size, and these were taken by the boys, while the third, a smaller room, went to Tom Rover.
“I’ve made a deal with Corning,” announced the twins’ father, when the Rovers were alone. “He is going to keep an eye on the office of the Rolling Thunder mine.”
“The office?” asked Jack. “Is he an expert bookkeeper, or something like that?”
“No, no! Nothing of that sort, Jack,” and Tom Rover smiled. “I’m simply going to have him watch, so that Garrish doesn’t take it into his head to have the records of the mining company carted away. I want to get at the bottom of this deal with that concern that is getting a good part of our ore.”
After that several days slipped by without anything unusual happening. Tom and the boys took a look around the outside of the mine, and even glanced in at the office. They saw Peter Garrish, but had no further words with him.
“He can stew until I’m ready to move,” said Tom to the boys. “I’ll wager he’s doing a lot of deep thinking right now.”
On the afternoon of the third day the boys rode over to Maporah to post some letters, the post-office being in Gus Terwilliger’s store.
“Here are some letters for you fellows, and also a letter for Mr. Rover,” said the storekeeper, and he handed the epistles over. “They came in on the noon train.”
“Hurrah! That’s just what we’ve been looking for,” cried Fred.
Then the boys went outside and sat down on the stoop of the store to read the communications.
“Here comes a fellow tearing along on horseback,” announced Jack, looking up. “He seems in a tremendous hurry.”
The rider had come from a trail which crossed the railroad close to the station. Now he sailed past the Terwilliger store at full speed. He wore a miner’s outfit, and the flap of his broad-brimmed hat flew
back in the breeze. In less than a quarter of a minute he was out of sight down a side trail.
“My stars!” ejaculated Fred, leaping to his feet. “Did you recognize that man?”
“It was Tate—the oil man from Texas!” answered Randy.
CHAPTER XXIII AT LAKE GANSEN
“Are you sure it was Tate?” demanded Andy, who had had his back turned to the rider.
“It certainly was,” answered his twin.
“What in the world can that man be doing here?” demanded Jack.
“Don’t ask me!” returned Randy. “I suppose now they’ve let him out of prison he has as much right to roam around as Davenport has.”
“I remember now that Tate did come from the West,” said Jack. “He was a miner before he became an oil man. Perhaps he’s interesting himself in the mines in this vicinity.”
“He couldn’t have anything to do with the Rolling Thunder mine, could he?” questioned Fred.
“I’m sure I don’t know.”
“Let’s go in and ask Mr. Terwilliger if he knows Tate,” suggested Fred, after a pause.
“Never heard of such an individual,” answered the storekeeper when the question had been put to him. “I don’t believe he belongs around here. Anyway, he doesn’t get any mail at this office.”
The boys talked the matter over for several minutes more. But then they were anxious to get at their letters and returned to the store stoop for that purpose. There were long letters from the girls postmarked at Jacksonville, Florida, where the steam yacht on which they were taking their outing had stopped. One letter to Jack was from Ruth, and this, it can well be imagined, the young major read with much interest. Ruth was enjoying herself greatly and trusted that Jack and his cousins were having a good time.
“Hello, here’s news that’s mighty interesting!” cried Randy “Here is a letter from Phil Franklin, and he says that he and Barry Logan have made half a dozen efforts to bring up the silver trophy from the bottom of the lake. He says that once they had it hooked up and brought it to the top of the water, but before they could grab it the thing slipped from the trawl and sank out of sight again.”
“Oh, what a shame!” murmured his twin. “To almost have it and then lose it again!”
“It’s just like the big fish that gets away,” returned Fred. “But, anyway,” he added, his face brightening, “they must know the exact spot now.”
“They do,” answered his cousin. “Phil writes that as soon as the vase slipped out of sight he and Barry took a piece of fish line, weighted it well, and let it go down to the bottom. Then they tied a bit of board to the top of the line, and on this hoisted a rag on a stick so they could see the board from a distance. He wrote this letter the day after the thing happened and said they were going out again just as soon as it stopped raining.”
“They’ll get it, I’m sure of it!” declared Jack.
“Well, I’ll feel better when that silver trophy is safe in the glass case in the gymnasium,” answered Randy.
All was going well with the folks who were taking the steam yacht trip, and for this the boys were thankful. They had a letter from Sam Rover, and from this learned that he and Jack’s father were exceedingly busy in Wall Street. There was also a letter from Dick Rover, but this was for Tom. When the latter received this communication he read it with great satisfaction.
“Your dad is right on the job,” he said to Jack. “He had been communicating with two other stockholders in the Rolling Thunder mine and has got them to put their proxies in my hands. That means that I can vote for them at any meeting of the stockholders that may be called. Those two men represent a hundred and ten thousand dollars’ worth of stock. And that means that I can get along without Leeds if I have to. All I shall want now is the backing of Mr Renton
and Mr Parkhurst and then I’ll be ready to put the screws on Garrish.”
The boys told Tom Rover of having seen Tate, and this interested the twins’ father at once.
“You want to keep your eyes open for that rascal,” said Tom. “He used to be in cahoots with Davenport, and he may be yet.”
“We’ll watch out for him, never fear,” answered Jack.
All of the boys were anxious to go farther westward on Sunset Trail and it was finally arranged for them to take an outing to last several days. They went on horseback, carrying such things as they needed with them.
“It’s a pretty wild country, don’t forget that,” said Tom Rover. “But you have been out before and have always been able to take care of yourselves, so I don’t suppose that I should worry. Just the same, remember that I shall be thinking of you,” and he smiled faintly.
“And we’ll be thinking about you, Dad,” said Andy. “I hope by the time we get back you’ll be in a position to tell Garrish where he gets off.”
“I hope so myself, Son.”
“I’ll bet you have a hot time with him when you tell him to clear out,” put in Randy.
“It’s awfully queer you don’t get some sort of word from that Lew Billings,” declared Jack.
“You couldn’t get word very well if he’s dead,” was Fred’s comment.
“Hank Butts gave me an idea yesterday,” said Tom Rover. “He’s got a hunch that Billings was made a prisoner by the Garrish crowd first and that he got away and is now in hiding, probably watching what is being done by that outside company that is taking some of our ore. Of course, Butts may be mistaken, but he’s a rather shrewd old fellow and may have struck the truth.”
As the weather was clear and warm the boys did not deem it necessary to take much in the way of shelter. They carried their sleeping bags and also a dog tent and blankets, and that was all. They took with them a few cooking utensils and a few necessary provisions.
“We know we can get fish and we ought to be able to get some small game,” said Jack. “Anyway, it won’t hurt us to rough it. If we have to starve a bit, why, that may be good for our digestions,” and he smiled faintly.
“We shan’t starve as long as we have got our beans and bacon,” answered Fred. “We’ll get along. We’ve done it before, and we can do it again.”
From Cal Corning they obtained directions regarding the best points to visit along Sunset Trail.
“That lake you fished in was Dogberry Lake,” said their host. “About ten miles farther on is Gansen Lake. I know you’ll like it up there. The fishing is good, and you ought to be able to stir up something in the way of game.”
Once on the road, the boys felt in high spirits and for the time being the trouble at the Rolling Thunder mine was forgotten. Swinging his cap high in the air, Andy led the way with Fred close behind him and Jack and Randy following.
“I’ll tell you what—this is the life!” sang out Andy gayly. “I feel as if I could keep riding right along to the Pacific Ocean.”
“Sounds good,” answered Fred. “But I think your horse will have something to say about that. You’d better take it a bit slow climbing these hills.”
The two Corning sisters had put up a lunch for the boys, and this was partaken of shortly after noon, when they reached a high spot on the trail. Here was a precipice, and standing on its brink they could look down into a stony valley six or seven hundred feet deep.
“Gee, this is a jumping-off place, I’ll say!” remarked Andy.
“It would be a bad spot for a runaway,” returned Jack.
Back of the precipice was some brushwood, as well as a number of tall trees, and here the boys proceeded to make themselves at home. They had sandwiches, cake, and some fruit, and that being so did not deem it necessary to start a fire for the purpose of making anything hot to drink. They had passed a spring in coming up to the precipice, and obtained a bucket of cool, clear water.
“This region is certainly a lonely one,” said Jack while they were eating. “Just think—we’ve been traveling for better than three hours and haven’t met a soul!”
“It would be a great place for a stage hold-up,” returned Randy “The bandits could get away with almost anything out here.”
“We don’t want any hold-up,” put in Fred. “All we want to do is to enjoy ourselves,” and he leaned back contentedly against a tree while munching a chicken sandwich.
A little later found the boys again on the way, and by three o’clock in the afternoon they came in sight of Gansen Lake. The lake was supplied from a mountain torrent and the torrent contained a waterfall ten or twelve feet in height and half that in width.
“Here is certainly an ideal place for camping out!” exclaimed Jack. “To my mind, it could not be better.”
“It’s all to the mustard!” sang out Andy. “Let’s unload right here and call it a day.”
“That lake looks mighty inviting to me,” declared Fred. “I’ll say a swim wouldn’t go bad.”
“Now you’ve said something!” burst out Randy. “Let’s get settled as soon as we can and then go swimming.”
The idea of getting into the lake after the long and somewhat warm ride appealed to all the lads, and in less than quarter of an hour they had their horses unloaded and properly tethered and then hurried down to a point along the lake shore where the water looked particularly inviting.
“I don’t suppose there can be anything dangerous in this lake,” said Jack.
“Nothing more dangerous than a few sharks and whales,” answered Andy, with a grin. “What did you expect to find here— leviathans?”
“There might be some water snakes,” put in Fred. “However, I’m not going to worry about that. I’m going to have a swim,” and without further words he proceeded to disrobe and the others did likewise.
At first the mountain water seemed exceedingly cold. But soon the boys got used to it, and then they proceeded to have as much fun as possible. They dived and raced, and Andy and his brother indulged in all manner of horseplay Near the shore they found the lake quite shallow, but farther out they were unable to touch bottom.
“These lakes are very deceiving,” said Jack. “Sometimes they lie right in between steep mountains and the bottom is hundreds of feet down.”
“We ought to be careful about diving too deep,” cautioned Randy. “There might be some outlet to this lake at the bottom. And if so, a fellow might be sucked down and be unable to come up again.”
“Let’s get up another race,” suggested Andy, after they had gotten through splashing water in each other’s faces.
“See that rock over yonder?” returned Fred. “Let’s race to that and back. Come on! Everybody ready?”
“All ready!”
“Then go!”
Away the boys started side by side, laughing and shouting merrily. Soon Randy pulled slightly to the front, with Jack close behind him.
“Hi, you fellows, wait for me!” spluttered Fred, who was last.
“The fellow who wins can cook supper for us!” sang out Jack.
“Nothing doing!” yelled back Randy. “The loser can cook supper and wash the dishes too.”
He came in ahead, the others following closely in a bunch. Then, somewhat out of breath, the four boys crawled out on some flat
rocks to rest before swimming back to where they had left their clothing.
“My gracious!” suddenly exclaimed Andy, and leaped to his feet in astonishment. “Look there, will you?”
He pointed across the water to a spot midway between where they had left their clothing and their camping outfit.
“Wolves!” breathed Jack. “Three of them! What do you know about that!”
CHAPTER XXIV
THE TIMBER WOLVES
“Now we are in a pickle!”
“I’ll say so! Why, we haven’t even got our clothing, much less our guns!”
“What are we going to do about it?”
“Don’t ask me! I was never good at answering riddles!”
Thus speaking, the four Rover boys gazed in wonder and astonishment at the sight before them. Sneaking along cautiously were three large gray timber wolves, gaunt and fierce in appearance. They had evidently been attracted to the spot by the scent of the boys and the horses and also, possibly, by the bacon in the supplies.
“There comes another one,” said Fred.
“Yes, and two more are crouched up on the rocks a short distance behind,” came from Jack.
“Six wolves! Maybe there’s a regular pack of them.”
“Shouldn’t wonder. They often travel in packs.”
“And they look hungry enough to eat us up,” came from Fred, and the tone of his voice showed that he felt anything but comfortable.
For the matter of that, all of the boys felt uneasy. Not only were they without their clothing but their four guns lay within a hundred feet of where the three leading wolves were standing.
The horses had also discovered the wolves and were now snorting wildly and trying to break from their tethers. Charley Boy, Randy’s mount, was particularly nervous, probably from his experience with the mountain lion.
The wolves had been sniffing first in the direction of the boys’ clothing and then in the direction of the supplies and the horses. Now they looked across the small arm of the lake at the boys themselves and uttered a series of snarls, baring their teeth as they did so.
“Oh, if I only had a rifle or a heavy shotgun!” murmured the young major.
“Can’t we heave some rocks at them?” suggested Fred.
“I don’t think it would do any good,” answered Randy. “We’re too far off. We were foolish to rove around in a wild place like this without our guns.”
Although the wolves snarled viciously, they did not as yet make any attempt to approach the four boys. Instead, while two sniffed at the clothing on the rocks, turning it over with their noses and paws, the others loped over to the supplies.
This was more than the horses could stand, and, plunging wildly, one after another broke his tether and shot off out of sight along the mountainside.
“Good-by to the horses!” cried Fred. “Now we sure are in a pickle even if we can manage to get rid of those wolves.”
“They’re coming this way!” yelled Randy.
“Pick up as many loose stones as you can carry,” ordered Jack. “Then wade out into the lake. I guess it’s about the only thing we can do.”
Three of the wolves were advancing around the arm of the lake in the direction of the boys. Evidently they were exceedingly hungry, for otherwise they would have run away at the sight of human beings.
Small stones were handy, and it did not take the four boys long to pick up half a dozen each. Then they waded out in the lake until they were in water up to their waists. By this time the three wolves had reached the flat rock on which the youths had been resting. They snarled repeatedly, showing their fangs, and their eyes gleamed in a
manner that indicated they would like nothing better than to get hold of the lads and make a meal of them.
“Let ’em have a dose of rocks!” cried Jack. “Be careful how you throw! Don’t waste your ammunition!”
“LET THEM HAVE A DOSE OF ROCKS,” CRIED JACK.
He let fly, and so did the others, and all the wolves were hit in the head or in the side. They set up a fearful howl of commingled pain and rage and then made a move as if to leap into the lake after the lads.
While this was going on the other wolves had approached the duffel bags of the boys and were tearing the outfit apart in an endeavor to get at the bacon and dried beef the lads carried.
Crack!
It was the report of a rifle and the shot startled the boys quite as much as it did the wolves. Then came a second crack, and, looking across the arm of the lake, the boys saw one of the big gray wolves leap into the air and fall back lifeless. Then came a third shot and a second wolf sprang into the air and then came down and with a wild snarl went limping away into the forest.
“Hurrah, somebody has come to our assistance!” cried Jack. “Give it to ’em! Give it to ’em good and plenty!” he yelled at the top of his lungs.
“Plug every one of ’em!” came from Andy.
“Shoot ’em down!” added his twin.
“Don’t let any of them get away!” was the way Fred expressed himself.
At the first crack of the rifle the three wolves that had come after the boys raised their heads to listen. Then, as they saw one wolf killed and another wounded, they waited no longer, but, turning, leaped swiftly over the rocks and then up the mountainside, their movements being hastened by a bullet that hit the rocks between them as they fled. In the meanwhile the remaining wolves had also taken their departure.
Satisfied that the coast was now clear, the boys swam across the arm of the lake. As they did this they saw a somewhat elderly man
approaching on horseback, his rifle in his hands. He was a tall man with a short-cut black beard and he wore a miner’s outfit.
“Reckon I come just about in time,” he sang out as he watched the approach of the boys. “Didn’t think any timber wolves would attack you like that.” And then he replaced the empty cartridges in the magazine rifle with fresh ones and waited for the lads to come up.
“It was fine of you to arrive as you did,” sang out Jack, who was the first out of the water. “We were caught good and plenty with our guns over in our outfits yonder.”
“Where do you belong? I don’t think I ever saw you before,” said the miner, as he dismounted. Then he added quickly: “You ain’t them Rover boys, are you?”
“Yes, we are,” answered Jack.
“Well, now, ain’t that great!” and the miner began to grin broadly. “Bet you a dollar you don’t know who I am.”
“We know you’re our friend,” came quickly from Fred.
“I’m Lew Billings,” answered the miner. “I guess Mr. Tom Rover has talked about me.”
“Lew Billings!” gasped all of the boys in concert.
“That’s it! And I’m downright glad I got here just in time to take care of them timber wolves for you. That one yonder is as dead as a doornail, and I don’t think them others will bother you again for a while. You see, timber wolves has been multiplying most amazing in Canada, and they’ve got so thick they’re slipping all over us down here. There’s a bounty on killing ’em, but what it is I don’t just know.”
“But where have you been, Mr. Billings?” questioned Randy. “My dad has been looking all over for you.”
“I know it, lad. But I had to lay low. I had a good reason for doing it, too. Your father will know all about it as soon as I reach him. I understand he’s stopping with Cal Corning.”
“He is,” put in Andy. And then he went on: “From what Hank Butts said, my dad thought you might have been made a prisoner by Mr.
Garrish.”
“So I was. And Garrish wanted me to sign some reports that was all false. I wouldn’t do it, and I got away from him and since that time I’ve been spying on him and on them fellers who’re running the Bigwater crusher. I’ve got a lot to tell Mr. Rover when I see him. And I’ve got an account to settle with Peter Garrish, too,” went on the old miner.
The boys dressed, and while so doing Lew Billings gave them a few particulars of what had happened to him. But he was in a hurry to go on and left them as soon as he felt satisfied that they were now able to take care of themselves.
“As you’ve all been to a military academy you ought to know how to shoot,” he declared. “And as you’ve got your guns and also a couple of pistols with you, it ain’t likely that you’ll have any more trouble—especially if you keep your firearms handy. You don’t want to prowl around in these mountains without some kind of a gun.”
“Believe me, you won’t catch us without our guns again,” answered Fred.
“Even when I sleep I’m going to have a pistol under my pillow,” added Randy.
They thanked Lew Billings heartily for what he had done and then watched the old miner as he rode away on Sunset Trail in the direction of Gold Hill Falls.
“If you ask me, I’ll say he was a friend in need if ever there was one,” declared the young major “I don’t know what we’d have done if he hadn’t come along.”
“It ought to be a lesson to us to be on our guard,” answered Fred.
“Now I am armed, oh, how I’d love to get a shot at those wolves!” remarked Andy
“What about the horses?” questioned Randy. “We’ve got to find those animals. I think the quicker we get after them the better If they’re allowed to stay away all night there’s no telling if we’ll ever be able to round ’em up.”
But rounding up the four horses proved easier than expected. None of them had gone away any great distance. Two of them were found on Sunset Trail just above the lake and the others in the bushes on the mountainside. They were rather difficult to handle for a few minutes, but presently calmed down when spoken to soothingly.
The boys did not know exactly what to do with the lean gray wolf that had been laid low by Billings’s bullet. At first they thought to skin the animal and save the pelt. But the hair was poor at this time of year, and none of the boys relished the labor, so they simply dragged the carcass down the lake shore for a distance, and then threw it in an opening between the rocks.
By nightfall the boys had erected their little shelter and had a campfire going, and all did their share in preparing the evening meal and in cleaning the dishes afterward.
“Wonder what will happen to-night,” said Randy, as they turned in, thoroughly tired out over the happenings of the day. “Maybe we’ll see more wolves, or a mountain lion or a bear.”
None of them cared to admit it, yet each was a trifle nervous, thinking that possibly the timber wolves might return. But nothing came to disturb them, and, having made sure that their campfire would not set fire to the forest around them, one after another fell asleep and slumbered soundly until after sunrise.
The next day proved to be one of unalloyed pleasure for all the boys. In the morning they went fishing and managed to get a goodsized catch. In the afternoon they tramped through the forest and there managed to bag several squirrels and also a somewhat larger animal which none of them could name.
“I thought we’d strike a bear, or something like that,” said Andy.
“I guess you want too much,” answered Fred, with a laugh.
The boys returned to camp while it was still light. All were hungry and immediately set to work to clean some of the fish for supper. They were hard at work at this when they saw a man on horseback riding rapidly toward them.
