Structural and Compositional Patterns in Forest Communities in the Intermountain West Across Multiple Scales

The United States Department of Agriculture (USDA) strives to use science-based research to both protect and enhance the management of natural resources. From this overarching goal, the USDA has a specific objective to protect the health and sustainability of forest and rangeland ecosystems. Based on this specific objective, an Advisory Board of natural resource scientists within the Quinney College of Natural Resources (QCNR) was awarded a National Institute of Food and Agricultural (NIFA) grant to train two PhD and two MS students. Their research would focus on managing for resilient forest ecosystem in the Intermountain West. With input from the advisory board and my PhD committee, my research focused on how to increase forest resilience at multiple scales. Locally, on the T.W. Daniel (TWD) Experimental Forest on the Logan Ranger District, three silvicultural trials were evaluated for resistance and resilience to the spruce beetle (partially funded by the TWD Forestry Fellowship). At the regional scale, a conceptual model was developed to classify forest communities based on structural features. The model was tested with data collected from 15 mountain ranges across the Intermountain West. Additionally, basic forest dynamics of limber pine (Pinus flexilis James.) were summarized across the Intermountain West. All three of these studies will aid in developing and implementing sound forest management practices to increase forest resilience

Building Resistance and Resilience: Regeneration Should Not be Left to Chance

Contemporary forest planning has tasked managers with developing goals associated with resistance and resilience. In practice, silviculturists use forest structure and tree species composition to characterize goals and desired future conditions, write prescriptions, and monitor outcomes associated with resistance and resilience. Although rarely discussed in the exploding literature relating to forest resistance and resilience, silvicultural regeneration methods are important and underutilized tools to meet these goals. We propose alternative silvicultural systems for building resistance and resilience to two common large-scale bark beetle disturbance agents in the Intermountain West, United States: mountain pine beetle (Dendroctonus ponderosae Hopkins) and spruce beetle (Dendroctonus rufipennis Kirby). Shelterwood, and shelterwood-with-reserves, silvicultural systems provide the desirable facilitative characteristics of a mature overstory on maintaining advance reproduction and the establishment of new cohorts of desirable tree species. These also allow the timely regeneration of large treatment areas necessary to rapidly promote desired future conditions in the face of inevitable disturbance. When implemented proactively, regeneration treatments allow silviculturists to take advantage of currently existing vegetation for the creation of age class and tree species diversity. In general, these examples illustrate the need for proactive planning for regeneration in response to any disturbance where desired future conditions include particular species. Furthermore, we argue that timely silvicultural interventions that focus on regenerating trees may be a key factor in achieving goals relating to resilience to specific disturbance types. Waiting until after the disturbance has occurred could result in the lost opportunity to establish desired species composition or stand structure—and may well result in a considerable restoration challenge

Landscape-Scale Drivers of Resistance and Resilience to Bark Beetles: A Conceptual Susceptibility Model

Bark beetle (Dendroctonus spp.) outbreaks in the middle latitudes of western North America cause large amounts of tree mortality, outstripping wildfire by an order of magnitude. While temperatures play an important, and direct role in the population dynamics of ectothermic bark beetles, an equally important influence is the nature of the host substrate—the structure and composition of forested communities. For many of the dominant tree species in the western United States, “hazard” indices have been developed for specific bark beetles, which generally include three key variables—host tree size, absolute or relative density of the stand, and percentage of host composition. We provide a conceptual model to apply these three variables across forest ecosystems and bark beetles that shifts the thinking from a species–specific model to a model which focuses on the underlying ecological factors related to bark beetle outbreak susceptibility. We explored the use of our model across multiple scales using the Forest Inventory and Analysis database: Interior West, USA; the states of Colorado and Arizona; and specific national forests within Arizona that are implementing a large-scale restoration effort. We demonstrated that across the Interior West and Colorado, the vast majority of forests have moderate to high susceptibility to bark beetles. Our conceptual model maintains the simplicity of previous “hazard” models but acknowledges the need to consider scale when managing bark beetles. It also shifts the management approach from resistance thinking to the development of “associational resilience”, where the focus is not on any one individual stand or area but the longer-term perspective of forest persistence across the landscape

Adaptive Silviculture for Climate Change in the Mississippi National River and Recreation Area, an Urban National Park in the Twin Cities Area, Minnesota

The Adaptive Silviculture for Climate Change (ASCC) Network is a collaborative effort to establish a series of experimental silvicultural trials across different forest ecosystem types. A variety of partners have developed trial sites as part of this multi-regional study researching long-term ecosystem responses to a range of climate change adaptation actions. We are currently implementing an affiliate trial within the Mississippi National River and Recreation Area, a national park along the Mississippi River in the Twin Cities Metro Area of Minnesota

Oral History Interview: Marcella Windmuller-Campione

Interviewed by Shana Edere

If Long-Term Resistance to a Spruce Beetle Epidemic is Futile, Can Silvicultural Treatments Increase Resilience in Spruce-Fir Forests in the Central Rocky Mountains?

Within the Central Rocky Mountains, spruce beetle populations have the potential to rapidly transition from endemic to epidemic levels in the spruce-fir (Engelmann spruce and subalpine fir) forest type. Conventional management has focused on creating resistance to spruce beetle outbreaks by manipulating the overstory density and composition. Three silvicultural treatments, single tree selection, group selection, and shelterwood with reserves, were established in a spruce-fir forest in northern Utah with the goals of increasing both resistance and resilience to outbreaks. Resistance and resilience metrics were explicitly defined. Pre-harvest and two post-harvest measurements were used to assess how the different silvicultural treatments influenced the metrics. The shelterwood with reserves was the only treatment to meet both the resistance and resilience criteria. This treatment, while not traditionally used, created a stand structure and composition that will be most resilient to climate induced increases in spruce beetle caused tree mortality. However, there will be a trade-off in composition and structure, especially Engelmann spruce, after a spruce beetle epidemic because the created structure is more uniform with fewer groups and gaps than commonly observed in spruce-fir forests. With changing climatic conditions, proactive forest management, such as the shelterwood with reserves in the spruce-fir forest type, is the best method for increasing short-term resistance and long-term resilience to spruce beetle outbreaks

Limber Pine (Pinus flexilis James), a Flexible Generalist of Forest Communities in the Intermountain West

As forest communities continue to experience interactions between climate change and shifting disturbance regimes, there is an increased need to link ecological understanding to applied management. Limber pine (Pinus flexilis James.), an understudied species of western North America, has been documented to dominate harsh environments and thought to be competitively excluded from mesic environments. An observational study was conducted using the Forest Inventory and Analysis Database (FIAD) to test the competitive exclusion hypothesis across a broad elevational and geographic area within the Intermountain West, USA. We anticipated that competitive exclusion would result in limber pine’s absence from mid-elevation forest communities, creating a bi-modal distribution. Using the FIAD database, limber pine was observed to occur with 22 different overstory species, which represents a surprising number of the woody, overstory species commonly observed in the Intermountain West. There were no biologically significant relationships between measures of annual precipitation, annual temperature, or climatic indices (i.e. Ombrothermic Index) and limber pine dominance. Limber pine was observed to be a consistent component of forest communities across elevation classes. Of the plots that contained limber pine regeneration, nearly half did not have a live or dead limber pine in the overstory. However, limber pine regeneration was greater in plots with higher limber pine basal area and higher average annual precipitation. Our results suggest limber pine is an important habitat generalist, playing more than one functional role in forest communities. Generalists, like limber pine, may be increasingly important, as managers are challenged to build resistance and resilience to future conditions in western forests. Additional research is needed to understand how different silvicultural systems can be used to maintain multi-species forest communities

Estudio de parámetros ergonómicos y de seguridad de la escuela municipal "Can Roig i Torres" de Santa Coloma de Gramanet

Este trabajo continua el trabajo iniciado con el proyecto básico, presentado en abril de 2004, incorporando las variacions de programa y de necesidades, introducidas en las diferentes reuniones mantenidas con representantes de la escuela y del ayuntamiento. En general con la redacción de este proyecto se pretende resolver la posibilidad de ampliar l’Escola Municipal de Música actual para incorporar un nuevo auditorio relacionado funcionalmente con ella, y además, con capacidad para ofrecer actuaciones al público de la ciudad, con aforo previsto 216 butacas

Landscape-Scale Drivers of Resistance and Resilience to Bark Beetles: A Conceptual Susceptibility Model

Bark beetle (Dendroctonus spp.) outbreaks in the middle latitudes of western North America cause large amounts of tree mortality, outstripping wildfire by an order of magnitude. While temperatures play an important, and direct role in the population dynamics of ectothermic bark beetles, an equally important influence is the nature of the host substrate—the structure and composition of forested communities. For many of the dominant tree species in the western United States, “hazard” indices have been developed for specific bark beetles, which generally include three key variables—host tree size, absolute or relative density of the stand, and percentage of host composition. We provide a conceptual model to apply these three variables across forest ecosystems and bark beetles that shifts the thinking from a species–specific model to a model which focuses on the underlying ecological factors related to bark beetle outbreak susceptibility. We explored the use of our model across multiple scales using the Forest Inventory and Analysis database: Interior West, USA; the states of Colorado and Arizona; and specific national forests within Arizona that are implementing a large-scale restoration effort. We demonstrated that across the Interior West and Colorado, the vast majority of forests have moderate to high susceptibility to bark beetles. Our conceptual model maintains the simplicity of previous “hazard” models but acknowledges the need to consider scale when managing bark beetles. It also shifts the management approach from resistance thinking to the development of “associational resilience”, where the focus is not on any one individual stand or area but the longer-term perspective of forest persistence across the landscape

Landscape-Scale Drivers of Resistance and Resilience to Bark Beetles: A Conceptual Susceptibility Model

Bark beetle (Dendroctonus spp.) outbreaks in the middle latitudes of western North America cause large amounts of tree mortality, outstripping wildfire by an order of magnitude. While temperatures play an important, and direct role in the population dynamics of ectothermic bark beetles, an equally important influence is the nature of the host substrate—the structure and composition of forested communities. For many of the dominant tree species in the western United States, “hazard” indices have been developed for specific bark beetles, which generally include three key variables—host tree size, absolute or relative density of the stand, and percentage of host composition. We provide a conceptual model to apply these three variables across forest ecosystems and bark beetles that shifts the thinking from a species–specific model to a model which focuses on the underlying ecological factors related to bark beetle outbreak susceptibility. We explored the use of our model across multiple scales using the Forest Inventory and Analysis database: Interior West, USA; the states of Colorado and Arizona; and specific national forests within Arizona that are implementing a large-scale restoration effort. We demonstrated that across the Interior West and Colorado, the vast majority of forests have moderate to high susceptibility to bark beetles. Our conceptual model maintains the simplicity of previous “hazard” models but acknowledges the need to consider scale when managing bark beetles. It also shifts the management approach from resistance thinking to the development of “associational resilience”, where the focus is not on any one individual stand or area but the longer-term perspective of forest persistence across the landscape