A recent review paper published in Conservation Letters entitled: Effects of logging on fire regimes in moist forests (Lindenmayer et al. 2010) focuses primarily on logging in moist forests where fires naturally occur at a lower frequency and higher intensity relative to dry forests. The manuscript represents a thorough review of over 650 research articles on fire, fire management, forest management, and conservation biology. The Lindenmayer et al. (2010) review is very relevant to management of our local moist, mixed conifer forests on the Umatilla and Wallowa-Whitman National Forests.
Lindenmayer et al. (2010) states: “Our focus is on relationships between industrial logging practices in native forests (i.e., not plantations) and alterations to natural fire regimes (sensu Gill 1975) that might include (among others) changed susceptibility to ignition, altered fire severity, altered fuel loads and fuel condition, and changed fire frequency. Altered fire regimes can have significant negative effects on biodiversity in moist forests (Holdsworth & Uhl 1997; Brown et al. 2004; Noss et al. 2006b; Lindenmayer et al. 2008), especially those forest types where wildfires are extremely rare or even a novel kind of major natural disturbance (e.g., some kinds of tropical rainforest, Uhl & Kauffman 1990; Cochrane & Barber 2009).”
In the Introduction, Lindenmayer et al. (2010) reminds us that logging cannot replace natural disturbance regimes: “However, we note that natural fire regimes cannot simply be replaced with regulated disturbance by logging (Hunter 2007). This is because, in part, many elements of forest flora and fauna depend on particular fire return intervals and associated habitat features (Saint-Germain et al. 2004). Logging operations also do not provide the diversity of habitats and micro site conditions found after wildfires (Haeussler & Kneeshaw 2003; Lindenmayer et al. 2008).”
Lindenmayer et al. (2010) identifies at least five interrelated ways that logging could influence wildfire frequency, extent and/or severity.
1. Changes in Microclimate: The removal of trees by logging creates canopy openings and this in turn alters microclimatic conditions, especially increased drying of understorey vegetation and the forest floor (Ray et al. 2005; Miller et al. 2007). As with the influence of forest edges (Harper et al. 2005), microclimate effects (including fuel drying) associated with forest harvesting can be expected to be greatest where the unmodified forest is moist.
2. Changes in stand structure and plant species composition: [Logging] changes not only alter microclimatic conditions as described above, but also can change stocking densities and patterns of trees, inter crown spacing, and other forest attributes such as plant species composition. Research in western North America indicates that logging related alterations in stand structure can increase both the risk of occurrence and severity of subsequent wildfires through changes in fuel types and conditions (Thompson et al. 2007).
3. Changes in fuel characteristics: Logging can alter fire regimes by changing the amount, type, and moisture content of fuels (Perry 1994; Weatherspoon & Skinner 1995; Thompson et al. 2007; Krawchuk & Cumming 2009). Large quantities of logging slash created by harvesting operations can sustain fires for longer than fuels in unlogged forest and also harbor fires when conditions are not suitable to facilitate flaming combustion or the spread of fire (Cochrane & Schulze 1999).
4. Change in ignition points: The road networks required for logging operations create an increased number of ignition points for wildfires. A substantial increase in ignitions and fire frequency in Russian boreal forests (Achard et al. 2006) has been attributed, in part, to roads built for logging and mining (Dienes 2004; Bradshaw et al. 2009). In Canadian mixedwood boreal forests, fire initiation following lightning strikes is more likely to occur in harvested areas because of increased fine fuels resulting from logging slash and this effect can remain for 10–30 years following logging (Krawchuk & Cumming 2009).
5. Change in the spatial pattern of stands: Logging operations change natural patterns of spatial juxtaposition of different kinds of forests stands (i.e., patterns of landscape heterogeneity) (Franklin & Forman 1987). This, in turn, can change spatial contagion in the spread of wildfire through landscapes (Whelan 1995; Bradshaw et al. 2009) with some areas traditionally characterized by an absence of fire becoming more susceptible to being burned by fires that spread from adjacent, more flammable, logged areas (Holdsworth & Uhl 1997; Perry 1998; Nepstad et al. 1999; Malhi et al. 2009). Similarly, forest edges created by logging and by logging roads can become sites for fire incursions into adjacent forests (Cochrane & Laurance 2002).
Lindenmayer et al. (2010) offers the following conclusions: “Contrary to claims by some commentators (e.g., National Association of Forest Industries 2009a,b,c), industrial logging is likely to make some kinds of forests more, not less, prone to an increased probability of ignition (Krawchuk & Cumming 2009) and increased fire severity and/or fire frequency (Uhl & Kauffman 1990; Thompson et al. 2007; Bradshaw et al. 2009; Malhi et al. 2009). Such places include tropical rainforests where fire was previously extremely rare or absent (Uhl & Kauffman 1990; Barlow & Peres 2004; Malhi et al. 2009), and other moist forests where natural fire regimes tend toward low frequency, stand replacing events (Whelan 1995; Odion et al. 2004; Bradshaw et al. 2009). These altered fire regimes can, in turn, have significant negative effects on a range of elements of forest biodiversity (Uhl & Kauffman 1990; Lindenmayer & Franklin 2002; Barlow & Peres 2004; Cochrane & Barber 2009).
“If industrial logging changes fire proneness, then interactions between logging and climate change could lead to cumulative negative impacts, including those on biodiversity. Conversely, recent work in Amazonia suggests that some kinds of forest may have some inherent resilience to climate change through maintaining mesic microclimate conditions if other agents such as logging are left undisturbed (Malhi et al. 2009). Third, a better understanding of relationships between logging and wildfire will improve policy making and forest management. For example, in moist forests there may be a case to create buffer areas adjacent to human settlements. In addition, there may be a strong case to exclude logging from those areas where past human disturbances (like timber harvesting) have been limited (Cochrane & Barber 2009). This is because logging induced alterations in landscape cover patterns can take prolonged periods to reverse and hence associated changes in fire susceptibility also may be long lived (Perry 1998).”
Lastly, Lindenmayer et al. (2010) states: “Calls to log forests to save them (Tuckey 2001) are overly simplistic. In this case, fire and forest management recipes suitable in one situation (e.g., for restoring the natural fire regime of a dry forest) might be inappropriate (and even counter productive) in another (e.g., a relatively moist forest) (Brown et al. 2004).”
If management actions in the Blue Mountains continue to target the remaining old growth moist forests, then these forests will become more rare and less able to support dependent native species. As we see today in the Ponderosa Pine/Douglas fir type, when old-growth forests are significantly reduced through logging, old growth associated species are greatly reduced as well. It is time we protect all remaining old growth forests from industrial logging.
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Ecosystem Conservation Coordinator
Hells Canyon Preservation Council