Recent research on the management of hemlock–spruce forests in southeast Alaska for multiple values

McClellan, Michael

doi:10.1016/j.landurbplan.2004.09.013

Cited by 11 publications

(10 citation statements)

References 27 publications

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“…These coastal forests also provide forage for the Sitka black-tailed deer (Odocoileus hemionus sitkensis), an important game animal throughout the region. Since the 1980s, much forest-related research in southeast Alaska has addressed the implications of various active forest management regimes on habitat of this commonly hunted species and biodiversity (McClellan 2005, Deal 2007); aspects of this research centered on oldgrowth habitat and the effects of land use practices, such as clearcutting or partial cutting on forage (Wallmo and Schoen 1980, Kirchhoff et al 1983, Hanley 1993. To date, researchers have not addressed the effects of yellow-cedar decline on the availability of key forage species.…”

Section: Introductionmentioning

confidence: 99%

Long‐term vegetation changes in a temperate forest impacted by climate change

et al. 2014

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Abstract. Pervasive forest mortality is expected to increase in future decades as a result of increasing temperatures. Climate-induced forest dieback can have consequences on ecosystem services, potentially mediated by changes in forest structure and understory community composition that emerge in response to tree death. Although many dieback events around the world have been documented in recent years, yellowcedar (Callitropsis nootkatensis) decline provides an opportunity to study vegetation changes occurring over the past century. Current research identifies climate-related reductions in snow cover as a key driver of this species dieback. To examine the process of forest development post-dieback, we conducted vegetation surveys at 50 plots along the outer coast of southeast Alaska across a chronosequence of mortality. Our main study objectives were to examine changes in seedling and sapling abundance, and community structure of conifer species in the overstory; effects of yellow-cedar mortality on plant diversity and community composition of functional groups in the understory; and volume of key forage species for Sitka black-tailed deer (Odocoileus hemionus sitkensis) managed throughout the region. The probability of yellow-cedar sapling occurrence was reduced across the chronosequence. Yellow-cedar seedling and sapling abundance also decreased. We observed a turnover from yellow-cedar to western hemlock (Tsuga heterophylla) dominated forests. Functional plant diversity increased and the community composition of the understory changed across the chronosequence. Bryophytes became less abundant and grasses more abundant in the early stages of stand development, and shrubs increased in relative abundance in latter stages. Our results demonstrate that yellow-cedar is significantly less likely to regenerate in forests affected by widespread mortality, and a species dieback can dynamically rearrange the plant community over time. These findings emphasize the importance of considering long-term temporal dynamics when assessing the impacts of climate change on biodiversity and ecosystem services, and adapting forest management to a changing climate.

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Section: Introductionmentioning

confidence: 99%

Long‐term vegetation changes in a temperate forest impacted by climate change

et al. 2014

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“…The study area was dominated by coniferous forests that varied in structure and composition with elevation (0–305 m), slope (10–40%), age, and silviculture history. In 2001, forests in southeast Alaska were comprised of young growth (7% of forests), productive old growth with large trees (5%), old growth with small‐and medium‐sized trees (47%), and muskeg and subalpine forest (41%; Barbour et al 2005, Caouette and DeGayner 2005, McClellan 2005, Albert and Schoen 2007).…”

Section: Study Areamentioning

confidence: 99%

“…Post‐harvest areas in the region typically receive no site preparation (McClellan 2005) and after 20–30 years are often characterized by high densities of small, closely spaced, naturally regenerating trees; single‐layered and closed forest canopies; and sparsely vegetated understories (Alaback 1982, Hanley 2005). Harvested stands may take longer than the rotation age of 70–100 years to exhibit characteristics of old‐growth forests (old growth; Alaback 1982).…”

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confidence: 99%

“…The goal of thinning is to reduce the number of regenerating trees competing for light and nutrients, increase the growth of the retained trees and understory vegetation, and ultimately accelerate succession of forest plant and animal communities (DellaSala et al 1996, Hayes et al 2003, Barbour et al 2005, Hanley 2005). Since 1950, over 86,000 ha of managed stands (32%) have been thinned in southeast Alaska; most thinning was pre‐commercial, took place after 1970, and did not involve post‐treatment applications of herbicides to control shrub growth (Barbour et al 2005, McClellan 2005). Despite the considerable attention to thinning in forest wildlife management in southeast Alaska, few studies have assessed whether thinning accelerates the succession of forest vegetation or wildlife communities in the region.…”

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confidence: 99%

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Succession of bird communities in young temperate rainforests following thinning

2012

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We repeated bird and vegetation surveys in 1991-1992 and 2005-2006 among young managed stands and old-growth forests in southeast Alaska to evaluate whether pre-commercial thinning of managed stands influenced the bird community. We compared decadal changes in bird densities and forest vegetation among 3 stand types: managed stands originating from clearcuts 35 years ago that were left untreated (unthinned), managed stands thinned at uniform spacing (thinned), and old growth with no prior timber harvest. We did not detect differences in decadal trends in avian densities between thinned and unthinned stands for 15 of 16 common bird species using a repeated-measures design. Thinning did not result in greater recruitment of overstory-nesting species as predicted. This was likely because of 1) similar increases in tree heights (x ¼ 9-10 m) and canopy cover (x ¼ 29-43%) between unthinned and thinned stands across decades and 2) the relatively young successional stage of these stands, which had only begun to recruit medium and large size conifers (dbh ! 36 cm). Decadal trends in densities of most (88%) understorynesting bird species did not differ between thinned and unthinned stands. Shrub cover decreased by 22% and 31% across decades in thinned and unthinned stands, respectively. Bird community composition in managed stands reflected the general decadal changes in forest vegetation with a shift in dominance from understory species in the early 1990s (80-85% of total bird density) to an equal abundance of understory (45-54%) and overstory species in the mid-2000s. The latter was more similar to old-growth stands, which were dominated by overstory species (67-71%). Overstory-nesting birds in old growth increased in density by 49% across decades. Densities of cavity-nesting species remained unchanged in managed stands and less than densities in old growth across decades, possibly because of a lack of large trees and snags for nest sites. Overall, thinning of clearcut stands, the primary silvicultural system in the region, had few measurable benefits to birds nearly 20 years after treatment. Monitoring over the 70-100-year harvest rotation may be necessary to fully test whether thinning accelerates succession of bird communities in clearcut stands. However, partial harvests that retain large trees and snags should also be explored as alternatives to better maintain late-succession avifauna throughout the harvest rotation in southeast Alaska. ß 2012 The Wildlife Society.

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“…These stands were harvested without a planned silvicultural system to ensure tree regeneration or stand growth. Forest managers are interested in developing silvicultural solutions to increase stand structural diversity and enhance biodiversity in these forests (McClellan 2005;Deal 2007).…”

Section: Introductionmentioning

confidence: 99%

Comparison of tree size structure and growth for partially harvested and even-aged hemlock-spruce stands in southeast Alaska

Deal

Heithecker

Zenner

2010

Journal of Forest Research

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The effects of partial cutting on tree size structure and stand growth were evaluated in 52 plots in 13 stands in southeast Alaska that were partially harvested 53-96 years ago and compared with 50-year-old even-aged stands that developed after clearcutting. The net basal-area growth was greater in the partially cut plots than in the uncut plots, and basal-area growth generally increased with increasing cutting intensity. However, the basal-area growth of all of the partially harvested stands was significantly less than the growth of 50-year-old even-aged stands, and net basal area growth over the 50 year period since partial harvesting was about 33-43% of the growth of the even-aged stands. Partial cutting maintained stand structures similar to uncut old-growth stands, and the cutting had no significant effect on tree species composition. The tree size distribution of the partially harvested stands was far more complex and well distributed in comparison with the 50-year-old even-aged stands, and included the presence of several trees with diameters of more than 100 cm. These trees included both large-diameter spruce and hemlock trees and were a distinctive structural feature that was noticeably lacking in the even-aged stands.

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Recent research on the management of hemlock–spruce forests in southeast Alaska for multiple values

Cited by 11 publications

References 27 publications

Long‐term vegetation changes in a temperate forest impacted by climate change

Long‐term vegetation changes in a temperate forest impacted by climate change

Succession of bird communities in young temperate rainforests following thinning

Comparison of tree size structure and growth for partially harvested and even-aged hemlock-spruce stands in southeast Alaska

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