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Aspen Restoration and Social Agreements: An Introductory Guide for Forest Collaboratives in Central and Eastern Oregon
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This document is part of a forest collaborative regional learning project on aspen restoration and social agreements. Many forest collaborative groups in the region have voiced an interest in addressing aspen restoration on their public lands of focus or Collaborative Forest Landscape Restoration (CLFR) projects. These groups consist of diverse stakeholders who work together to support forest restoration on public lands for mutual ecological, economic, and social outcomes through consensus-based dialogue and decision making. This often occurs during the management agency’s planning or NEPA process. Although the agency retains final decision-making authority, common ground agreements that collaboratives achieve can assist in identifying socially acceptable restoration treatments, and are intended, in part, to reduce the likelihood of objections and litigation.
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In eastern Oregon in the USA, there has been a debate about restoring forest health to address overstocking, insects and disease, and uncharacteristic wildfire. Stakeholder “forest collaborative” groups have formed for dialogue about these issues. Little is known about how these groups function and how they conceive of forest health. We examined seven forest collaboratives, finding that forest health is an umbrella term often used to indicate general need for forest restoration including thinning and prescribed burning. Concepts such as historic range of variability, structure, and species diversity were more commonly discussed than specific insects and diseases. There is a fairly high degree of satisfaction among participants with how well forest collaboratives are achieving their desired outcomes.
An experimental assessment of the use of clearfell harvesting to initiate a regeneration response in commercially managed aspen forests affected by sudden aspen decline (SAD) was conducted in western Colorado in cooperation with the USDA Forest Service. Nine pure commercial quality aspen stands, with three levels of mortality attributed to SAD, were selected (three replicates per mortality level). Half of each stand was clearfelled, and half was left uncut. The aspen regeneration response was monitored for three growing seasons after harvest in the cut and uncut treatments. Cut treatments with low and moderate mortality had the best subsequent regeneration response, and those with the heaviest mortality exhibited the poorest regeneration response. Uncut treatments exhibited very little regeneration response, regardless of the initial overstory mortality level. Dead trees in the uncut overstory were projected to fall within 15 years. These results indicate that it is possible to successfully regenerate aspen forests affected by SAD, provided that treatment occurs before the majority of the aspen are dead.
Quaking or trembling aspen (Populus tremuloides Michx.) forests occur in highly diverse settings across North America. However, management of distinct communities has long relied on a single aspen-to-conifer successional model. We examine a variety of aspen-dominated stand types in the western portion of its range as ecological systems, avoiding an exclusive focus on seral dynamics or single-species management. We build a case for a large-scale functional aspen typology based on the existing literature. Aspen functional types are defined as aspen communities that differ markedly in their physical and biological processes. The framework presented here describes two “functional types” and seven embedded “subtypes”: seral (boreal and montane), stable (parkland, Colorado Plateau, elevation and aspect limited, and terrain isolated), and a crossover seral-stable subtype (riparian). The assessment hinges on a matrix comparing proposed functional types across a suite of environmental characteristics. Differences among functional groups based on physiological and climatic conditions, stand structures and dynamics, and disturbance types and periodicity are described herein. We further examine management implications and challenges, such as human alterations, ungulate herbivory, and climate futures, that affect the functionality of these aspen systems. The functional framework lends itself well to stewardship and research that seek to understand and emulate ecological processes rather than combat them. We see advantages of applying this approach to other widespread forest communities that engender diverse functional adaptations.
Trembling aspen (Populus tremuloides Michx.) regeneration dynamics including sprout production, growth, and clone size were measured to determine the effects of fire on small aspen clone persistence following a mixed-severity wildfire in the Black Hills, South Dakota. Four years postfire, 10 small, isolated aspen clones per low and high fire severity classes were compared with 10 unburned clones. Regardless of severity, fire did not cause an increase in the area occupied by individual aspen clones. Clones affected by high severity fire had the greatest suckering response producing an average of 31 930 sprouts(.)ha(-1); more than double the sprout density in unburned clones and 67% greater than the sprout density in clones affected by low severity fire. Sprout growth in high severity clones was 135% and 60% greater than sprout growth in unburned and low severity clones. The succession of these clones to more shade-tolerant ponderosa pine was delayed in clones affected by high severity fire as high severity fire caused significant pine mortality within and surrounding the clone, whereas, without further disturbance, pine encroachment and dominance will likely continue in clones affected by low severity fire.
In the northwest Great Basin, western juniper (Juniperus occidentalis subsp. occidentalis Hook.) is encroaching into aspen (Populus tremuloides Michx.) communities. There is a concern that aspen communities in this region are in a state of decline, but their status has not been documented. This study determined the timing, extent, and some of the effects of this expansion. Ninety-one aspen stands were sampled for density, canopy cover, age, stand structure, and recruitment of western juniper and aspen. Soils and tree litter beneath aspen and western juniper were collected to analyze the effects of western juniper on soils. Additionally, 2 large aspen complexes in southeast Oregon were intensively aged to determine disturbance (fire) frequencies. Western juniper encroachment peaked between 1900 and 1939 with 77% of all juniper trees sampled having been established during this period. Three-fourths of aspen stands sampled have established populations of western juniper. Twelve percent of aspen stands sampled were completely replaced by western juniper and another 23% dominated by western juniper. Average density of western juniper in aspen sites was 1,573 trees ha-1. Seventy percent of aspen stands sampled had zero recruitment of new aspen. Aspen stands averaged 98 years old. There was an inverse correlation between aspen canopy cover and western juniper canopy cover. Soils influenced by western juniper had a higher C:N ratio, pH, salts, lime, and sulfate, and lower amounts of magnesium, iron, copper, and manganese. Aspen litter had a lower C:N ratio than western juniper litter. Two major aspen complexes sampled had even-age, 2-tiered even-age, and multiple-age aspen trees. The absence of presettlement juniper within all sampled aspen stands suggests fire was the primary stand-replacing disturbance in these northwest Great Basin aspen communities. The lack of fire coupled with aspen stand decadence and low recruitment levels will allow for the continued encroachment and replacement of aspen communities by western juniper in the northwest Great Basin. /// En la Gran Cuenca del noroeste el "Western juniper" (Juniperus occidentalis subsp. occidentalis Hook.) esta invadiendo las comunidades de "Aspen" (Populus tremuloides Michx.). Existe una preocupación respecto a si las comunidades de "Aspen" de esta región están en un estado de deterioro, pero este punto no ha sido documentado. Este estudio determinó la época, cantidad y algunos efectos de esta expansión. Se muestrearon 91 poblaciones de "Aspen" en las cuales se midió la densidad, cobertura de la copa, edad, estructura de la población y establecimiento de "Western juniper" y "Aspen". Bajo los árboles de "Aspen" y "Western juniper" se colectó suelo y mantillo de árboles para analizar los efectos del "Western juniper" en los suelos. Adicionalmente 2 grandes complejos de "Aspen" situados en el sudeste de Oregon fueron intensivamente muestreados para conocer su edad y determinar las frecuencias de disturbio (fuego). La invasión de "Western juniper" alcanzó su pico entre 1900 y 1939, periodo en el cual se estableció el 77% de los árboles de "Juniper" muestreados. En el 75% de las poblaciones de "Aspen" muestreadas se habían establecido poblaciones de "Western juniper". El 12% de estas poblaciones de "Aspen" fueron completamente remplazadas por "Western juniper" y otro 23% fue dominado por "Western juniper". La densidad promedio de "Western juniper" en los sitos de "Aspen" fue de 1,573 árboles ha-1. El 70% de las poblaciones de "Aspen" muestreadas no presentaron establecimiento de nuevas plantas de esta especie. Las poblaciones de "Aspen" promediaron una edad de 98 años. Hubo una correlación inversa entre la cobertura de copa del "Aspen" y la cobertura de copa del "Western juniper". Los suelos influenciados por "Western juniper" tuvieron valores mas altos en la relación C:N, pH, sales, cal y sulfato y por otra parte tuvieron menores cantidades de magnesio, fierro, cobre y manganeso. El mantillo de "Aspen" tuvo una menor relación C:N que el mantillo de "Western juniper". Los dos complejos principales de "Aspen" que se evaluaron tuvieron una edad uniforme, 2 estratos de edad uniforme y árboles de "Aspen" de edad múltiple. Todas las poblaciones de "Aspen" estudiadas presentaron ausencia de "Juniper" antes de la de colonización, lo que sugiere que el fuego fue el principal factor de remplazo de las poblaciones de especies en estas comunidades de "Aspen de la Gran Cuenca del noroeste. La falta de fuego acompañada de la decadencia de la población de "Aspen" y sus bajos niveles de establecimiento permitirán que en la Gran Cuenca del noreste ocurra una invasión continua y el remplazo de las comunidades de "Aspen" por comunidades de "Western juniper".
Land managers in the Pacific Northwest have reported a need for updated scientific
information on the ecology and management of mixed-conifer forests east of the
Cascade Range in Oregon and Washington. Of particular concern are the moist
mixed-conifer forests, which have become drought-stressed and vulnerable to
high-severity fire after decades of human disturbances and climate warming. This
synthesis responds to this need. We present a compilation of existing research
across multiple natural resource issues, including disturbance regimes, the legacy
effects of past management actions, wildlife habitat, watershed health, restoration
concepts from a landscape perspective, and social and policy concerns. We provide
considerations for management, while also emphasizing the importance of local
knowledge when applying this information at the local and regional level.
Western juniper (Juniperus occidentalis spp. occidentalis Hook.) woodlands are rapidly replacing lower elevation (< 2 100 m) quaking aspen (Populus tremuloides Michx.) stands throughout the northern Great Basin. Aspen restoration is important because these communities provide critical habitat for many wildlife species and contain a high diversity of understory shrubs and herbaceous species. We studied two juniper removal treatments to restore aspen woodlands. Treatments included cutting one-third of the juniper trees followed by early fall burning (FALL) or early spring burning (SPRING). Selective cutting of juniper was performed to increase cured surface (0-2 m) fuel levels to carry fire through the woodlands. We tested treatment effectiveness at removing juniper from seedlings to mature trees, measured aspen sucker recruitment, and evaluated the response to treatment of shrub and herbaceous cover and diversity. In the FALL treatment, burning eliminated all remaining juniper trees and seedlings, stimulated a 6-fold increase in aspen suckering (10 000 ha-1), but initially resulted in a significant reduction in herbaceous cover. Spring burning removed 80% of the mature juniper trees that remained after cutting. However, 50% of juniper juveniles survived the SPRING treatment, which will permit juniper to redominate these stands in less than 80 years. Aspen suckering in the SPRING increased only 2.5-fold to 5 300 stems ha-1 by the third year after fire. In the SPRING, herbaceous cover increased 330% and the number of species observed doubled by the third year after fire. If the management objective is to eliminate western juniper with minimal cutting and stimulate greater aspen suckering, we recommend that woodlands be burned in the fall. If the objective is to maintain shrub and herbaceous cover and moderately increase aspen suckering, spring burning is recommended. With spring burning it appears follow-up management will be necessary to remove juniper that are missed in initial treatments.
The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use man-agement of the Nation's forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the national forests and national grasslands, it strives—as directed by Congress—to provide increasingly greater service to a growing Nation. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.
Sudden decline (SAD), affecting Populus tremuloides, was first observed in Colorado in 2004. By 2008 it affected at least 220,000 ha, an estimated 17% of the cover type in the state. In southwestern Colorado, we examined site and stand features in paired
A conventional view of regeneration ecology of quaking aspen (Populus tremuloides Michx.) in western North American holds that reproduction is strictly vegetative and, except on some marginal sites, only successful following high-severity disturbance. This view has strongly influenced silvicultural treatment of western aspen and has led to low expectations concerning genetic diversity of stands and landscapes. However, recent discoveries are fundamentally altering our understanding of western aspen regeneration ecology and genetics. For example, there are clearly multiple pathways of aspen regeneration and stand development. Research on a variety of fronts indicates that seedling establishment is common enough to be ecologically important and that genetic diversity is substantially greater than previously thought. We review conventional understanding of western aspen and put this into the context of silvicultural practice. We then review recent developments in aspen research and assess the silvicultural implications of these insights.
