Forest Investment Account (FIA) - Forest Science Program
FIA Project M085126

    Predicting biodiversity maintenance after bark beetles and MPB management
 
Project lead: Martin, Kathy (University of British Columbia)
Contributing Authors: Norris, Andrea R.; Martin, Kathy; Aitken, Kathryn E.H.; Drever, Mark C.; Davidson, Peter; Easton, Wendy
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
In 2007, bark beetle infection levels will reach their peak in Interior BC forests, including our study sites (Fig 1). With field work and analyses of existing data, we will evaluate the impacts on wildlife communities of epidemic and post-epidemic MPB conditions and of beetle management activities. The health of mixed coniferous forests is a critical management issue in BC with implications and impacts on the forest industry, biodiversity conservation and regional land use planning. Interior BC forests have high biodiversity (>200 vertebrate species), and many wildlife species have strong preferences for large and decayed trees for nesting and feeding (Martin et al. 2004, Drever & Martin 2007). As salvage operations focus on mature pine stands, retention of remaining old mixed forests will become increasingly important to support the rich assemblage of resident and migrant wildlife (Martin et al. 2006). Insect outbreaks and fire are the two major natural disturbance factors structuring the succession of mature conifer stands (Kilgore 1978). The current outbreak of mountain pine beetle in interior BC is at a larger scale and intensity than previously experienced, raising the concern that wildlife species may be strongly impacted by these dramatic changes in forest health (Conner et al. 2001). Wildlife population dynamics may become unstable due to the cumulative effects of changes on the landscape caused by cutting of old forest, declines in tree health caused by insect outbreaks, increases of >2.5 deg C in winter and spring minimum temperatures, beetle management activities resulting in a major uplift of the AAC, and fire suppression. Despite the regularity of insect outbreak events, the vast amounts of forest habitat involved, and the importance of understanding natural disturbance regimes for effective ecosystem management, beetle outbreaks remain a natural disturbance type that is essentially unstudied for BC forest ecosystems, or elsewhere in North America. Since 1995, we have conducted population and community level studies on >180 wildlife species in the Cariboo-Chilcotin region of interior BC to determine the critical habitat attributes and wildlife responses to several silvicultural treatments (selection cutting with variable retention, beetle hazard reduction, salvage cutting; Martin et al. 2002). We monitored tree health conditions annually using standard forest inventory, wildlife tree and forest health techniques for >10,000 tagged trees on 29 mixed stands. We have determined critical habitat attributes and population trends for many species in healthy old forest stands (Martin et al. 2004). From 1995-2005, the percent of dead and dying conifers increased from 6% to 55%, with numbers of dead trees rising sharply in 2004 (Martin et al. 2006). Over this period, 40% of 101 bird and mammal species showed significant population changes, with some increasing and others in sharp decline (Drever & Martin 2007). For many insectivorous cavity nesters, bark beetle-attacked stands initially represented an enhancement of habitat quality for foraging (Bull et al. 1986). Since 2001, cavity nester populations increased, and moved to nesting patches with high density MPB-attacked trees, with year round residents showing greater increases than migratory species (K. Martin, Unpubl data). However, as the epidemic proceeds, conditions can deteriorate as the supply of forest insects and old trees decline (Stone 1995). On our study sites, MPB benefits declined as tree mortality exceeded 40%; by 2006 several species were in steep decline. We urgently need to determine which forest conditions will support wildlife populations through peak and post-epidemic conditions. We describe below how we will address this question. In 2007, we will evaluate the role of insect outbreaks and beetle management activities on wildlife biodiversity at the peak and in post-epidemic conditions in mature mixed conifer forests. We will also evaluate the longer-term impacts of forest management responses to beetle outbreaks (hazard reduction by removing attacked green trees and salvage cutting), treatments that can alter habitat quality by removing structure and feeding trees. Initially, cavity nesters had negative responses to beetle hazard reduction treatments (Martin et al. 2002), but 7 years later these sites support good wildlife populations. Such temporal variation in responses demonstrates that forest managers need to be mindful of retaining an adequate supply of critical habitat attributes on the landscape today and over the next 50 years. At landscape and regional scales, extensive areas of mature conifers (mostly pine) have been cut, leaving only remnants of old forest and a reduced supply of critical habitat attributes. Future responses to peak MPB and post-peak conditions by wildlife species will depend on their ability to use recently-cut stands and the remnant forests, both in terms of the tree species used (possibly more use of Douglas-fir and spruce) and how they are used. We will determine from our field study and data which post-epidemic habitats serve best as wildlife refuges. Management options on crown lands need to balance the priorities of biodiversity conservation and timber extraction (Snetsinger 2006), and consider the needs of forest species during and after the epidemic. In other words, we need to ensure the maintenance of habitats for wildlife populations after their 'boom and bust' response to dead trees when forest landscapes are extensively cut. REFERENCES: (See Martin CV for Martin and Drever citations) BULL, EL, SR Peterson & JW Thomas 1986. Resource partitioning among woodpeckers in northeastern Oregon. U.S. Dept Agric & Forest Service, Pacific NW Res Stn, Res Note PNW-444, Portland, Or CONNER, RN, DC Rudolph & JR Walters 2001. The red-cockaded woodpecker: Surviving in a fire maintained ecosystem. Univ. Texas Press, Austin, Tex. KILGORE, BM 1978. Fire in ecosystem distribution and structure: Western forests and scrublands. In Fire regimes and ecosystem properties. HA Mooney et al. (tech coords). U.S. Dept Agric & Forest Service, Wash, D.C. Tech Rept WO-26, pp 5889. SNETSINGER, J 2006. Forest stewardship and allowable annual cuts in British Columbia today. BC JEMS 6(1): STONE, WE 1995. The impact of a mountain pine beetle epidemic on wildlife habitat and communities in post-epidemic stands of a lodgepole pine forest in northern Utah. PhD thesis. Utah State Univ, Logan, Utah.

    Deliverables:

Woodpeckers as Indicators (Biol.Con., 141, p. 624-634)
Beetlemania article (Bird Watch Canada 39: 8-11) Not available online?
Forest Birds & Beetle Eaters Exercise (18Kb)
Resource Selection Plasticity article [Ecology, 89(4)]
Woodpecker Article [Picoides 21(1), p. 13]
MPB and Red-Breasted Nuthatches article [Journal of Wildlife Management, (72)3,]

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Updated August 16, 2010 

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