The Challenge of Large-scale Natural Disturbances and Salvage Logging

Wildfires and other large-scale forest disturbances figure prominently in forested regions of the world. These disturbances (nominally "forces of nature") are events with a high public profile because of their threats to human life and values, occurrence in famous places, and their spatial scale. Peri-urban areas of major metropolitan regions, such as Los Angeles and Sydney, regularly experience intense wildfire. There have been many widely publicized and large-scale disturbances, such as the eruption of Mount St. Helens in 1980, the Yellowstone fires in 1988, well-known hurricanes such as Hugo (1989) and Katrina (2005), the Columbus Day windstorm of 1964, and the Boxing Day tsunami of 2004.

Large natural disturbances have occurred recently in many regions of the world. Wildfires burned nearly 10 million hectares in a single year (1997–98) in Indonesia (Food and Agriculture Organization 2001), 7 million hectares in 1995 in Canada (Canadian Council of Forest Ministers 2007), 3 million hectares in the 2002–3 fire season in southeastern Australia (Australian Bureau of Statistics 2004), 2.7 million hectares in 1997 in Mongolia (Food and Agriculture Organization 2001), 2 million hectares in 2000 in the United States, and 800,000 hectares in Mexico in 1998 (Food and Agriculture Organization 2001). European forests experience damage to 35 million cubic meters of wood annually (table 1.1), and impacts of the agents of disturbance are increasing (Schelhaas et al. 2003).

Large and novel disturbances are likely to increase as a consequence of climate change (Hobbs et al. 2006; Westerling et al. 2006). In interior British Columbia, more than 13 million hectares of lodgepole pine (Pinus contorta var. latifolia) forest have been affected by the mountain pine beetle (Dendroctonus ponderosae) (British Columbia Ministry of Forests and Range 2006, 2007) (fig. 1.1), and the epidemic of this native pest has spread into neighboring Alberta and could even invade stands of a new host species, jack pine (Pinus banksiana). Such unusual behavior of the mountain pine beetle is believed to be the result of unprecedented expanses of mature pine forest (due to widespread forest fires a century ago and subsequent fire control), coupled with warming winter temperatures and consequent improved survival of overwintering insect broods (Carroll et al. 2004).

Natural and Other Disturbances

Throughout this book we refer to natural disturbances. As is further described in chapter 2, these disruptions are recognized as discrete events in time and place that cause widespread mortality of trees. We distinguish such unplanned disturbances that "nature" generates from scheduled hu-man disturbances of forests, such as timber harvesting, road building, and land clearing for agriculture. Although varying in importance around the world, many or most forest fires in a region may originate from human ignitions, and other disturbances such as landslides can also be induced by human actions. It is debated whether such forests would eventually burn from lightning ignitions anyway, and whether modern rates of human-caused ignitions are more or less than those practiced by indigenous peoples for millennia. Insect populations preying on forest trees may have been introduced from another continent, or may be undergoing exponential growth as a result of increasing temperatures or the loss of predators. The frequency and strength of many weather-related disturbances such as hurricanes seem to be a consequence of global warming induced by fossil fuel consumption, and are expected to continue increasing in the future (Dale et al. 2001). As such, it could be argued that a large proportion of the "natural disturbances" affecting forests have their origin in human activities.

Salvage Logging

Salvage logging is a common response to natural forest disturbances. Salvage logging is defined by the Society of American Foresters (Helms 1998, 158) as "the removal of dead trees or trees damaged or dying because of injurious agents ... to recover economic value that would otherwise be lost."

In practice, salvage logging often also results in the removal of undamaged live trees along with the dead or damaged ones (Shore et al. 2003; Foster and Orwig 2006). Salvage logging is widely practiced throughout the world (table 1.2).

Salvage logging may occur after a wide variety of disturbances, such as the following:

• Wildfires (McIver and Starr 2000; Nappi et al. 2004; Hutto 2006)

• Insect attacks (Radeloff et al. 2000; Shore et al. 2003; Foster and Orwig 2006)

• Hurricanes, cyclones, and other severe windstorms (Nilsson 1975; Savill 1983; Foster and Orwig 2006)

• Floods (Gregory 1997) and debris flows (Beschta, 1979)

• Volcanic eruptions (Eggler 1948; Franklin et al. 1985; Dale et al. 2005)

Most of the literature on salvage logging is related to wildfires (table 1.2), although there are regional differences in the dominant disturbance agent: fires in Australia and western North America, windstorms in Europe and eastern North America (table 1.2), and insects and fire in Canada and, more generally, in boreal regions.

Salvage logging is practiced in all forested regions of the world including tropical forests (Van Nieuwstadt et al. 2001) and boreal and temperate forests (McHugh 1991; Che and Woen 1997; Kulakowski and Veblen 2007). It is also applied in plantations (Holtam 1971; Shakesby et al. 1993, 1996; Rackham 2001). Salvage logging is most prevalent in ecosystems where natural disturbances occur as partial or complete stand-replacement events (McIver and Starr 2000; Lindenmayer and Noss 2006).

Salvage logging has been practiced for a long time and is a concept and practice dating back to the origins of forestry. Enormous volumes of Norway spruce (Picea abies) were salvaged after being killed by insects in the mid-nineteenth century and again in the mid-twentieth century (Bejer 1988; Christiansen and Bakke 1988). Salvage logging of portions of the 1902 Yacolt Burn were among Weyerhaeuser Company's earliest operations in the U.S. Pacific Northwest. Forests in western Oregon damaged by the 1933 Tillamook Burn were salvaged continuously until at least 1959 and probably 1971 (Wells 1998). Wet eucalypt forests in Australia were salvaged after wildfires in 1926, 1932, and 1939 (Lindenmayer and Ough 2006; see figure 1.2 and chapter 4).

Salvage logging programs can be substantial and prolonged. One of the largest salvage programs in the United States followed the 1938 Hurricane in the New England region (Foster and Orwig 2006). Large areas of private, state, and federal timber affected by the 1980 Mount St. Helens eruption were salvage logged (Franklin et al. 1985, 1995). Harvesting of fire-damaged timber near Campbell River on Vancouver Island provided wood to mills in Vancouver, British Columbia, for at least a decade (Mackie 2000). After Storm Gudrun (called Erwin in Germany) struck Sweden in January 2005, forest-harvesting equipment and operators were mobilized from across northern Europe to rapidly salvage most of the 7.5 million cubic meters of damaged timber (Sondell 2006; fig. 1.3).

Salvaged timber now represents a significant percentage of the wood harvested in many regions of the world. At least 78 percent of the wood volume damaged by natural disturbances in Europe is salvaged (Schelhaas et al. 2001), generating 8 percent of the annual wood harvest (Schelhaas et al. 2003). In 2005, approximately 40 percent of logging on federal forestlands in the USA was focused on salvaging timber from fire-damaged stands. In the states of Washington and Oregon, the proportion of timber from salvage logging increased from 14 percent between 1980 and 1988 to 21 percent between 1989 and 1998 (McIver and Starr 2000). Salvage of dead tree boles now represents 20 percent of British Columbia's current cut from public forests.

Economic Rationale for Salvage Logging

Many justifications for salvage logging have been offered, but the most obvious and defensible rationale is economic (Cannell and Coutts 1988; Ulbricht et al. 1999; Akay et al. 2006). Salvage logging can capture some of the economic value in dead and damaged trees that would otherwise be lost, whether in the form of timber, pulpwood, or fuelwood (U.S. Government Accountability Office 2006; Prestemon et al. 2006). Some consumers may perceive that wood products from salvaged dead trees are more environmentally friendly than products made from wood harvested from green stands (Donovan 2004).

When large amounts of timber are salvaged, that timber is typically substituted for green (live) wood that would have been harvested during that same time period. Large salvage logging programs may generate so much timber that they disrupt markets by flooding them with wood (Prestemon et al. 2006). This can significantly disrupt revenue streams (Kohnle and von Teuffel 2004; Luppold and Sendak 2004) and disrupt the future availability of resources for harvesting in the medium and long term (Eggler 1948; Spittlehouse and Stewart 2003). Large salvage logging programs also may generate wood in excess of regional processing (mill) capacity, necessitating creative responses from wood products industries. For example, a five-year supply of logs was salvaged and preserved in ponds and lakes until needed following the 1938 New England Hurricane. The 1962 Columbus Day windstorm in the U.S. Pacific Northwest blew down 2,360,000 cubic meters of timber, most of which was salvaged; the wood products industry created an Asian log export market to move this large volume of salvaged timber.

Other Rationales for Salvage Logging

Many noneconomic justifications have also been proposed for salvage logging. There is, of course, the natural tendency of societies to want to bring order back from the "chaos" created by large disturbance events (Hull 2006). In particular, Western societies find the perception of waste and disorder to be anathema (Noss and Lindenmayer 2006). Hence, major efforts may be mounted to "clean up" after large, intense disturbance events.

The following are some of the specific justifications offered for salvage beyond economics or general societal inclinations to restore order:

• Safety concerns, such as the hazards created by large numbers of standing dead trees or snags for people working or recreating in burned areas (Ne'eman et al. 1997; Shore et al. 2003).

• Reducing fuels available for subsequent fires, on the basis that the dead wood provides abundant fuels and increases fire risk for re-burns on the disturbed area as well as the adjacent forest (Sessions et al. 2004; British Columbia Ministry of Forests and Range 2006, 2007; Passovoy and Fule 2006). Snags are a particular concern as they can generate firebrands (Inbar et al. 1997; Orwig and Kittredge 2005).

• Reducing fuels to limit the amount of smoke produced in subsequent prescribed burns and, in turn, limit the effects of smoke on nearby settlements (Achtemeier 2001).

• Reducing the potential for dead and dying trees to become breeding grounds for pests and pathogens that would invade adjacent unaffected forests (Holtam 1971; Christiansen and Bakke 1988; Amman and Ryan 1991; Hughes and Drever 2001). For example, outbreaks of spruce beetle (Dendroctonus rufipennis) in the U.S. state of Colorado have traditionally followed extensive windthrow events (Schmidt and Frye 1977; Lindemann and Baker 2001).

• An expectation that some damaged trees will inevitably die from pest infestations, and the desire to remove them before they are killed (Brooks 2004; Foster and Orwig 2006).

Salvage logging has also been justified on the basis that it will contribute to ecological recovery of naturally disturbed forests (Sessions et al. 2004). This is, in part, based on the following perceptions:

• Legacies of dead and damaged trees do not contribute to the recovery of ecosystem processes and biodiversity (Sessions et al. 2004).

• Ecosystem recovery will be assisted or accelerated by speeding the re-establishment of forest cover (Bartlett et al. 2005; Sessions et al. 2004).

• Naturally disturbed areas have limited value for biota (Morissette et al. 2002).

The notion that salvage logging assists the ecological recovery of naturally disturbed forests is fundamentally incorrect (Lindenmayer et al. 2004). Hence, justifications for salvage logging based on contributions to ecological recovery have little merit. We know of few circumstances where salvage logging has been demonstrated to directly contribute to recovery of ecological processes or biodiversity. Under some circumstances, salvage logging can indirectly contribute through generation of funds for restorative activities. Conversely, there is abundant theoretical and empirical evidence (presented later in this volume) that salvage logging interferes with natural ecological recovery (Lindenmayer and Ough 2006) and may increase the likelihood and/or intensity of subsequent fires (e.g., Kulakowski and Veblen 2007; Thompson et al. 2007). As Jerry Franklin stated,

based on our current understanding of forest recovery following disturbances, timber salvage is most appropriately viewed as a "tax" on ecological recovery. The tax can either be very large or relatively small depending upon the amount of material removed and the logging techniques that are used (2005, 2).

Indeed, the term salvage itself is problematic ecologically given that the word means "recovering or saving" (Lindenmayer and Noss 2006). We return to this issue of terminology in chapter 6.

Importance of This Book

We based this book on the following premises:

• Large forest disturbances have been and will remain significant and prominent events, with the possibility that there will be increasing numbers and novel forms of disturbances as a consequence of climate change.

• Society has come to consciously value forests much more broadly than simply as sources of wood, such as for the ecological services that they provide (e.g., watershed protection) and for the biodiversity that they support.

• There is much relevant scientific literature that should be considered during the development of policies and management approaches regarding disturbed forest landscapes.

Our objective in this book is to examine the ecological consequences of salvage logging for a broad audience of stakeholders. We recognize that ecological values are only one of the criteria society uses in making forest management decisions, including post-disturbance activities such as salvage logging. Similarly, science provides only one of the relevant knowledge bases. Nevertheless, we believe that a synthesis of ecological science relevant to salvage logging is important to fully inform public dialogue. When decisions are made regarding salvage and other post-disturbance activities, they should be made with clarity about the rationale for those activities.

A detailed consideration of salvage logging appears particularly timely in view of climate change. There is increasing evidence that one of the results of climate change is that large disturbance events are becoming more frequent (Cary 2002), widespread (Flannigan et al. 2005; British Columbia Ministry of Forests and Range 2006), intense (Emanuel 2005), or all of these (Franklin et al. 1991; Lenihan et al. 2003; Pittock 2005). There is already statistical evidence that as a result of climatic change there has been an increase in the extent and intensity of wildfires (Westerling et al. 2006), more numerous and intense hurricanes (Goldenberg et al. 2001), and a massive collapse of tree populations under novel infestations of native insects (Breshears et al. 2005). Hence, there is the potential for salvage logging proposals to become even more widespread and frequent (Schelhaas et al. 2003; Spittlehouse and Stewart 2003).

Although numerous volumes deal with ecological impacts of traditional ("green") logging and ways they can be mitigated (e.g., DeGraaf and Miller 1996; Franklin et al. 1997; Hunter 1999; Burton et al. 2003b; Lunney 2004), no equivalent volume deals with salvage logging. This book is an attempt to redress this imbalance.

Finally, we acknowledge the primacy of management objectives in determining appropriate post-disturbance management activities for affected areas, including the relative weights given to ecological and economic values. The process of evaluating various courses of action should begin with a consideration of management goals for the property, whether they involve wood production, watershed protection, conservation of biodiversity, or, as is most often the case, a mixture of economic and ecological goals.

Structure of This Book

This book is composed of a series of short, linked chapters. First, chapter 2 presents a brief overview of natural disturbance regimes in forests as a basis for examining issues associated with salvage logging. Potential ecological impacts of salvage logging are considered in chapter 3. Brief reviews of a wide variety of salvage logging projects are provided in chapter 4; these short case studies aim to highlight the diversity of issues associated with salvage logging. Chapter 5 is a discussion of the importance of management objectives in determining post-disturbance management policies, since the spatial scale and intensity of salvage logging should relate to those objectives. Chapter 6 also considers some forest management policy implications of salvage logging. A glossary that defines key terms associated with salvage logging completes this book.