Conserving Forest Biodiversity

A Comprehensive Multiscaled Approach

David B. Lindenmayer,Jerry F. Franklin

• Publisher: Island Press
• Year: 2013
• ISBN:
  9781597268530
• Topic: Ciencias biológicas
• Subtopic: Ciencias en general

While most efforts at biodiversity conservation have focused primarily on protected areas and reserves, the unprotected lands surrounding those area—the "matrix"—are equally important to preserving global biodiversity and maintaining forest health. In Conserving Forest Biodiversity, leading forest scientists David B. Lindenmayer and Jerry F. Franklin argue that the conservation of forest biodiversity requires a comprehensive and multiscaled approach that includes both reserve and nonreserve areas. They lay the foundations for such a strategy, bringing together the latest scientific information on landscape ecology, forestry, conservation biology, and related disciplines as they examine:

• the importance of the matrix in key areas of ecology such as metapopulation dynamics, habitat fragmentation, and landscape connectivity
• general principles for matrix management
• using natural disturbance regimes to guide human disturbance
• landscape-level and stand-level elements of matrix management
• the role of adaptive management and monitoring
• social dimensions and tensions in implementing matrix-based forest management

In addition, they present five case studies that illustrate aspects and elements of applied matrix management in forests. The case studies cover a wide variety of conservation planning and management issues from North America, South America, and Australia, ranging from relatively intact forest ecosystems to an intensively managed plantation.

Conserving Forest Biodiversity presents strategies for enhancing matrix management that can play a vital role in the development of more effective approaches to maintaining forest biodiversity. It examines the key issues and gives practical guidelines for sustained forest management, highlighting the critical role of the matrix for scientists, managers, decisionmakers, and other stakeholders involved in efforts to sustain biodiversity and ecosystem processes in forest landscapes.

PART I

Principles for Biodiversity Conservation in the Matrix

Part I primarily explores the topic of matrix management. This is because much of the focus of conservation biologists has been on reserve allocation, with conservation management outside these protected-area networks receiving only limited attention.

In Chapter 1 we define what we mean by “the matrix”—landscape areas not designated primarily for conservation purposes. We also define what we consider to be ecologically sustainable forest management given its critical importance for conserving biodiversity in the matrix. Most of Chapter 1 is given over to a discussion of the critical roles of the matrix for biodiversity conservation, including supporting populations of species, regulating the movement of organisms, buffering sensitive areas and reserves, and maintaining the integrity of aquatic ecosystems. Finally, we briefly highlight the limitations of reserve systems and why these roles for the matrix are critical for biodiversity conservation, a theme that is revisited in considerable detail in Part II (Chapter 5).

Because the role of the matrix for biodiversity conservation has largely been ignored in much of ecology and conservation biology, Chapter 2 is dedicated to an exploration of the importance of the matrix in key topics such as metapopulation dynamics, habitat fragmentation, and landscape connectivity. This sets a theoretical and applied framework for identifying a set of general principles to guide matrix management in Chapter 3. We argue that the overarching principle for matrix management is the maintenance of suitable habitat at multiple spatial scales. Underpinning this is the maintenance of stand structural complexity, the maintenance of connectivity, the maintenance of landscape heterogeneity, and the maintenance of aquatic ecosystem integrity. Because of the varying needs of different species at different spatial and temporal scales coupled with the uncertainty of the effectiveness of any given single strategy in its own right, a fifth guiding principle—risk—spreading, or the application of multiple conservation strategies—is also discussed in Chapter 3. A sixth principle—using knowledge and inferences from natural disturbance regimes—is such a large and important topic in informed matrix management for biodiversity conservation that an entire chapter (Chapter 4) is dedicated to it. The fundamental premise of this chapter is that the impacts of human disturbance on forest biodiversity can be reduced if those impacts are within the bounds of natural disturbance regimes such as fires, floods, and windstorms.

The four chapters in Part I set a practical and theoretical foundation for the detailed discussion in Part II of a multiscaled set of approaches to conserving forest biodiversity ranging from large ecological reserves to individual trees within managed stands. How these approaches are implemented will vary between stands, landscapes, and regions. No generic “cookbook” can be applied uncritically everywhere. This is clearly demonstrated in the series of case studies that are featured in Part III, which also illustrate many of the critical roles of the matrix and reemphasize the general principles for matrix management that are the core of Part I. These case studies also highlight many of the social and political realities of matrix management in the real world, which Parts IV and V discuss in greater detail.

CHAPTER 1

Critical Roles for the Matrix

The days are over when the forest may be viewed only as trees and the trees viewed only as timber.

—U.S. SENATOR HUBERT HUMPHREY (IN PATTON 1992)

The conservation of biodiversity is one of the fundamental guiding principles for ecologically sustainable forest management. Many existing conservation programs are limited to a primary or exclusive focus on lands contained in reserves for biodiversity conservation. Yet, most forest will be in off-reserve, or matrix, lands in the vast majority of forest regions and forest types. Comprehensive strategies for the conservation of forest biodiversity must include both reserves and matrix-based strategies. The importance of the matrix for the conservation of biodiversity in forests reflects its dominance in both temperate and tropical regions—most forest landscapes have been, or will be, actively used and managed. Therefore, many forest-dependent species will occur primarily in matrix !ands—or not at all.

How the matrix is managed will influence the size and viability of populations of many forest taxa and thus biodiversity per se. Matrix conditions also greatly influence connectivity between reserves and the movement of organisms. In addition, by acting as buffers, matrix conditions strongly control reserve effectiveness. The matrix must sustain functionally viable populations of organisms that are fundamental to the maintenance of essential ecosystem processes such as nutrient cycling, seed dispersal, and plant pollination—processes that underpin the long-term productivity of ecosystems and their ability to produce goods and services for human use.

The conservation of biodiversity has become a major concern for resource managers and conservationists worldwide, and it is one of the foundation principles of ecologically sustainable forestry (Carey and Curtis 1996; Hunter 1999). This represents a major challenge for forest management because forests support approximately 65 percent of the world’s terrestrial taxa (World Commission on Forests and Sustainable Development 1999). They are the most species-rich environments on the planet, not only for vertebrates, such as birds (Gill 1995), but also for invertebrates (Erwin 1982; Majer et al. 1994) and microbes (Torsvik et al. 1990).

Setting aside networks of dedicated reserves has been the traditional approach advocated by many conservation biologists to conserve the extraordinary biodiversity that characterizes forest ecosystems. Many books and vast numbers of scientific articles have been written on reserve design and selection (Shafer 1990; Noss and Cooperrider 1994; Margules et al. 1995; Anonymous 1996; Pigram and Sundell 1997). In this book, we argue that the conservation of a significant proportion of the world’s forest biodiversity will require a far more comprehensive and multiscaled approach than simply partitioning forest lands into reserves and production areas, which we term the matrix. This book attempts to lay the foundations for such a comprehensive strategy. Although large ecological reserves are discussed (see Chapter 5), most of this book addresses management of the matrix.

Most temperate and subtropical forest landscapes are composed primarily (or even exclusively) of off-reserve forests, or matrix lands. It has been estimated that between 90 and 95 percent of the world’s forests have no formal protection (Sugal 1997). This is particularly true in temperate regions where the most productive (and species-diverse) forested lands have already been extensively modified by humans (Franklin 1988; Virkkala et al. 1994). Therefore, forests outside reserves are extremely important for the conservation of biodiversity—how they are managed will ultimately determine the fate of much biodiversity.

Our primary objective in this book is to illustrate the importance of the matrix for biodiversity conservation and to propose strategies for enhanced matrix management that can be the basis for a comprehensive approach to maintaining forest biodiversity. We begin in this first chapter by providing our definitions of biodiversity and the matrix. We then illustrate the importance of the matrix for conserving forest biodiversity.

Defining Biodiversity and Ecologically Sustainable Forest Management

There are many definitions of biodiversity. Ours is relatively simple:

Biodiversity encompasses genes, individuals, demes, metapopulations, populations, species, communities, ecosystems, and the interactions between these entities.

There are also many interpretations of ecologically sustainable forest management (Amaranthus 1997). Ours follows Lindenmayer and Recher (1998):

Ecologically sustainable forest management perpetuates ecosystem integrity while continuing to provide wood and non-wood values; where ecosystem integrity means the maintenance of forest structure, species composition, and the rate of ecological processes and functions with the bounds of normal disturbance regimes.

Two other terms widely used in this book are stands and landscapes. We define a stand as “a patch of forest distinct in composition or structure or both from adjacent areas.”

This definition is often inadequate, such as when modified cutting practices like retention at the time of harvest are employed (see Chapter 8); this means that stands can actually be composed of structural mosaics (Franklin et al. 2002). However, the simple definition is widely used and understood (see Helms 1998) and, except where noted, we use it in this book.

Given that the focus of this book is on forests, we crudely define a landscape as “many sets of stands,” or patches, that cover an area ranging from many hundreds to tens of thousands of hectares. Drainage basins are a good landscape unit, but it often is necessary to consider much smaller areas or very large regional landscape units.

Defining the Matrix from a Conservation Biology and Landscape Ecology Perspective

In the technical language of landscape ecology, the matrix is defined as the dominant and most extensive “patch type” (Forman 1995; Crow and Gustafson 1997). Other criteria used in its definition include the portion of the landscape that is best connected and that has a controlling influence over key ecosystem processes such as water and energy flows (Forman 1995).

In conservation biology and forest planning literature, the “matrix” often refers to areas that are not devoted primarily to nature conservation. In temperate regions in particular, these areas are generally available for resource extraction and use, including the production of commodities, as well as for many other human uses. The definitions of “matrix” from both landscape ecology and conservation biology perspectives are congruent in many temperate regions where reserved lands are clearly in the minority. Conversely, in undeveloped regions, the matrix sensu landscape ecology (the dominant patch type) may not be equivalent to the matrix sensu conservation biology because the majority of the forested land is in a “natural” condition. For this book, we have adopted a very broad definition of the matrix:

The matrix comprises landscape areas that are not designated primarily for conservation of natural ecosystems, ecological processes, and biodiversity regardless of their current condition (i.e., whether natural or developed).

Much of our focus is on biodiversity conservation in wood production areas outside the dedicated reserve system because land allocation in many jurisdictions around the world has created a distinction between reserves and commodity landscapes. The term matrix management is used frequently throughout the book, and it refers to approaches to conserve biodiversity in forests outside the reserve system.

Critical Roles for the Matrix

There are four critical roles the matrix plays that relate specifically to biodiversity conservation: (1) supporting populations of species, (2) regulating the movement of organisms, (3) buffering sensitive areas and reserves, and (4) maintaining the integrity of aquatic systems.

Conditions in the matrix will determine the degree to which it contributes positively or negatively to these roles.

Conserving biodiversity for its own sake is only one of many possible goals of matrix management. Another is the production of commodities, such as wood, and services, such as well-regulated flows of high-quality water. Management practices in the matrix will determine whether these goods and services can be sustained, because such practices also influence whether elements of biodiversity critical to long-term sustainability, such as mycorrhizal-forming fungi, are maintained (Perry 1994). Such organisms need to be conserved at functionally effective levels to maintain ecosystem processes (Conner 1988). Hence, conservation of biodiversity in the matrix is fundamental to achieving intrinsic goals (e.g., sustainable production of wood products...