• Document: Maintenance of Forest Ecosystem Health and Vitality
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Maintenance of Forest Ecosystem Health and Vitality Ryan D. DeSantis and W. Keith Moser Introduction OREST HEALTH WILL likely be threatened by a number of factors—including fragmentation, fire regime alteration, and a variety of diseases, insects, and invasive plants—along with global climate change (Krist et al. 2007, Tkacz et al. 2008). By itself, global climate change could dramatically and rapidly alter forest composition and structure (Allen and Breshears 1998, Allen et al. 2010). In conjunction with other threats, global climate change poses unique challenges to forest management by influencing forest dynamics at virtually all levels: disturbance regimes in forest ecosystems; rates of resource availability and utilization; canopy gap formation and woody debris dynamics; fire regimes; community composition; and forest distribution, structure, biodiversity, and biogeochemistry. Global climate change and other threats, in turn, could favor the establishment of invasive species. The following pages discuss effects of the most pertinent threats to the future health of forests in the Northern United States. OVERVIEW OF THREATS The threats vary considerably in the amount of forest area they affect and in their rate of The major biotic threats affecting northern spread, but collectively the North surpasses forests (USDA FS, n.d.a) include: other regions of the country in the number of • Oak decline invasive forest pests per county (Liebhold • Asian longhorned beetle et al. 2013). Some threats are not yet broadly (Anoplophora glabripennis) established but pose serious concern for • Gypsy moth (Lymantria dispar) future forests nonetheless (Tables 5.1, 5.2). • Emerald ash borer (Agrilus planipennis) Although some have been successfully mitigated, • Hemlock woolly adelgid (Adelges tsugae) contained, controlled, or even eradicated, others • Beech bark disease continue to spread unimpeded throughout • Sirex woodwasp (Sirex noctilio) northern forests (Fig. 5.1). • Spruce budworm (Choristoneura fumiferana) • Winter moth (Operophtera brumata) CHAPTER FIVE 107 Key Findings • Forest threats like emerald ash borer, hemlock • Fire regime changes have substantially decreased woolly adelgid, beech bark disease, and gypsy the abundance of fire-tolerant and fire-adapted moth are causing major changes to forests. vegetation like oaks and have contributed to • Insects such as the Asian longhorned beetle, invasion by fire-intolerant mesic species. spruce budworm, Sirex woodwasp, and winter • Invasive plants are contributing to habitat moth have exhibited the potential to decimate loss, ecosystem degradation, and decreasing a variety of tree species and could become more species diversity. formidable to forests in urban and rural areas. • Other threats such as deforestation and fragmentation • Emerald ash borer could decimate the entire U.S. contribute to worsening forest health conditions, population of ash, which is culturally significant to which provide increased opportunities for invasions Native American populations, valuable for specialty to spread. products, and valued in urban landscapes. • Although forest threats have always existed, • Decline-disease complexes such as oak decline are present-day challenges to forest ecosystem causing negative ecological and economic effects. health, diversity, and resilience are unprecedented. FIGURE 5.1 Areas in the North predicted to have ≥25-percent mortality risk from oak decline, southern pine beetle, gypsy moth, pine engraver beetle, or hardwood decline by 2030 (USDA FS, n.d.e). Nonforest Forest Forest insect and disease risk 108 FUTURE FORESTS OF THE NORTHERN UNITED STATES Table 5.1—Occurrence of th

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