Above- and below-ground effects of aspen clonal regeneration and succession to conifers

Shepperd, Wayne D.; Bartos, Dale L.; Mata, S. A.

doi:10.1139/cjfr-31-5-739

Cited by 33 publications

(28 citation statements)

References 5 publications

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“…Poor regeneration of aspen has been associated with conifer succession or conversion to shrubs and grasses (Schier et al, 1985;Shepperd et al, 2001). Aspen cover may be lost on some sites if most of the overstory is dead, root systems are in poor condition, and little regeneration is present.…”

Section: Discussionmentioning

confidence: 99%

“…Root systems regressed in deteriorating stands, surviving primarily near the residual live stems (Schier, 1975). In southern Utah, deteriorating aspen stands had lower root densities than adjoining healthy stands (Shepperd et al, 2001), and suckering was suppressed by apical dominance of residual stems over the smaller root systems (Schier, 1975;Schier and Campbell, 1980). As in the Great Lakes region, observations suggested that genotype was an important factor determining which clones deteriorated.…”

Section: Introductionmentioning

confidence: 99%

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Rapid mortality of Populus tremuloides in southwestern Colorado, USA

Worrall¹,

Egeland²,

Eager³

et al. 2008

Forest Ecology and Management

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229

288

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Concentrated patches of recent trembling aspen (Populus tremuloides) mortality covered 56,091 ha of Colorado forests in 2006. Mortality has progressed rapidly. Area affected increased 58% between 2005 and 2006 on the Mancos-Dolores Ranger District, San Juan National Forest, where it equaled nearly 10% of the aspen cover type. In four stands that were measured twice, incidence of mortality increased from 7-9% in 2002/2003 to 31-60% in 2006. Mortality generally decreased with increasing elevation over the primary elevation range of aspen and occurred on less steep slopes than healthy aspen. Slope-weighted mean aspects of aspen cover type were northern at low elevations and generally southern at high elevations. Relative frequency of mortality was generally highest on southern to western aspects. In 31 stands measured in detail, mortality ranged from 0 to 100% (mean 32%) and was negatively correlated with stand density (P = 0.033). Size of trees affected was strongly correlated with amount of current mortality (P < 0.001), and current mortality was skewed toward larger diameter classes. Density of regeneration was in a low range typical of undisturbed stands and did not increase with overstory mortality.Agents that typically kill mature trees in aspen stands were unimportant in this mortality. Instead, a group of interchangeable, usually secondary agents was most commonly associated with mortality, including Cytospora canker (usually caused by Valsa sordida), aspen bark beetles (Trypophloeus populi and Procryphalus mucronatus), poplar borer (Saperda calcarata), and bronze poplar borer (Agrilus liragus). The rapidity of mortality, mortality agents involved, and probably other causal factors distinguish this phenomenon from the long-term loss of aspen cover usually attributed to successional processes operating in an altered disturbance regime (and often exacerbated by ungulate browsing). Our data are consistent with a hypothesis that (a) predisposing factors include stand maturation, low density, southern aspects and low elevations; (b) a major inciting factor was the recent, acute drought accompanied by high temperatures, and; (c) contributing factors and proximate agents of mortality are the common biotic agents observed. On sites with poor regeneration and weak root systems, clones may die, resulting in the long-term loss of aspen forest cover. Published by Elsevier B.V.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rapid mortality of Populus tremuloides in southwestern Colorado, USA

Worrall¹,

Egeland²,

Eager³

et al. 2008

Forest Ecology and Management

Self Cite

229

288

View full text Add to dashboard Cite

show abstract

“…Within a century of stand establishment conifer height growth will equal or exceed that of aspen. The current shift in conifer dominance in mixed stands is likely to be the result of this change in competitive superiority from aspen to conifer stems (McKenzie, 2001;Shepperd et al, 2001;Kaye, 2002). Since the last major fire events on the Plateau were recorded in 1879, the shifts in dominance measured 100 years later appear to be consistent with natural historic variation in vegetation cover for aspen forests in the western Rocky Mountains.…”

Section: Discussionmentioning

confidence: 99%

Twenty-year change in aspen dominance in pure aspen and mixed aspen/conifer stands on the Uncompahgre Plateau, Colorado, USA

Smith

2005

Forest Ecology and Management

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“…An example of more recent successful establishment of aspen followed the severe fires in Yellowstone National Park in 1988, which apparently provided a Bwindow of opportunity^of suitable substrate and climate conditions for seed germination (Romme et al 2005). Although aspen clones are long lived, possibly thousands of years (Kemperman and Barnes 1976), individual stems normally live 100-150 years (Mitton and Grant 1996;Shepperd et al 2001). Since sexual regeneration requires prolonged moist conditions and is thought to be rare for xeric aspen, it is possible that an aspen clone lost from the landscape will not regenerate from seed (Mitton and Grant 1996).…”

Section: Aspen Ecologymentioning

confidence: 99%

“…These stable aspen systems are unsuitable for conifers or are located far away from conifer seed sources (Mueggler 1989). In biophysical settings where aspen is seral to conifer species, slowgrowing shade-tolerant conifers begin to overtop aspen late in succession, eventually outcompeting the aspen, leading to aspen loss (Shepperd et al 2001).…”

Section: Aspen Stressorsmentioning

confidence: 99%

Long-term monitoring of western aspen—lessons learned

Strand

Bunting

Starcevich

et al. 2015

Environ Monit Assess

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Aspen woodland is an important ecosystem in the western United States. Aspen is currently declining in western mountains; stressors include conifer expansion due to fire suppression, drought, disease, heavy wildlife and livestock use, and human development. Forecasting of tree species distributions under future climate scenarios predicts severe losses of western aspen within the next 50 years. As a result, aspen has been selected as one of 14 vital signs for long-term monitoring by the National Park Service Upper Columbia Basin Network. This article describes the development of a monitoring protocol for aspen including inventory mapping, selection of sampling locations, statistical considerations, a method for accounting for spatial dependence, field sampling strategies, and data management. We emphasize the importance of collecting pilot data for use in statistical power analysis and semi-variogram analysis prior to protocol implementation. Given the spatial and temporal variability within aspen stem size classes, we recommend implementing permanent plots that are distributed spatially within and among stands. Because of our careful statistical design, we were able to detect change between sampling periods with desired confidence and power. Engaging a protocol development and implementation team with necessary and complementary knowledge and skills is critical for success. Besides the project leader, we engaged field sampling personnel, GIS specialists, statisticians, and a data management specialist. We underline the importance of frequent communication with park personnel and network coordinators.

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Above- and below-ground effects of aspen clonal regeneration and succession to conifers

Cited by 33 publications

References 5 publications

Rapid mortality of Populus tremuloides in southwestern Colorado, USA

Rapid mortality of Populus tremuloides in southwestern Colorado, USA

Twenty-year change in aspen dominance in pure aspen and mixed aspen/conifer stands on the Uncompahgre Plateau, Colorado, USA

Long-term monitoring of western aspen—lessons learned

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