Compilation by Robyn Darbyshire
Egan, D., M. Stoddard, et al. (2015). “Ecological and social implications of employing diameter caps at a collaborative forest restoration project near Flagstaff, Arizona, USA.” Forest Policy and Economics 52: 39-45.
The issue of implementing diameter caps as a means of preserving old-growth trees on forest restoration projects continues to permeate collaborative land management discussions and treatment decisions on public lands in the Southwest and, indeed, throughout the western United States. We examine the ecological and social results of the collaborative Fort Valley Ecosystem Restoration Project on U.S. Forest Service lands near Flagstaff, Arizona. Since this experiment had areas treated with and without a diameter cap, we sought to determine: 1) the ecological consequences of implementing a 16-inch diameter cap, 2) whether the fears and concerns of the environmental groups who proposed the diameter cap were, in fact, warranted, and 3) how the local collaborative responded to implementing the diameter cap. The ecological data revealed that a site’s management history played a major role in how a diameter cap would affect the restoration of stand structure in terms of tree density and tree size. The data suggest that, if implemented, diameter caps are best applied in a manner that takes into account both site conditions and stand management history. In general, we found the concerns about the loss of old-growth trees due to thinning treatments were not realized at Fort Valley. Finally, stakeholder surveys indicate that while the discussion of diameter caps caused tension within the collaborative group, the overall goal of forest restoration was not compromised.
Yetemen, O., E. Istanbulluoglu, et al. (2015). “Ecohydrologic role of solar radiation on landscape evolution.” Water Resources Research 51(2): 1127-1157.
Solar radiation has a clear signature on the spatial organization of ecohydrologic fluxes, vegetation patterns and dynamics, and landscape morphology in semiarid ecosystems. Existing landscape evolution models (LEMs) do not explicitly consider spatially explicit solar radiation as model forcing. Here, we improve an existing LEM to represent coupled processes of energy, water, and sediment balance for semiarid fluvial catchments. To ground model predictions, a study site is selected in central New Mexico where hillslope aspect has a marked influence on vegetation patterns and landscape morphology. Model predictions are corroborated using limited field observations in central NM and other locations with similar conditions. We design a set of comparative LEM simulations to investigate the role of spatially explicit solar radiation on landscape ecohydro-geomorphic development under different uplift scenarios. Aspect-control and network-control are identified as the two main drivers of soil moisture and vegetation organization on the landscape. Landscape-scale and long-term implications of these short-term ecohdrologic patterns emerged in modeled landscapes. As north facing slopes (NFS) get steeper by continuing uplift they support erosion-resistant denser vegetation cover which leads to further slope steepening until erosion and uplift attains a dynamic equilibrium. Conversely, on south facing slopes (SFS), as slopes grow with uplift, increased solar radiation exposure with slope supports sparser biomass and shallower slopes. At the landscape scale, these differential erosion processes lead to asymmetric development of catchment forms, consistent with regional observations. Understanding of ecohydrogeomorphic evolution will improve to assess the impacts of past and future climates on landscape response and morphology.
FULL TEXT LINK: http://dx.doi.org/10.1002/2014WR016169
Franklin, J. and K. Norman Johnson (2014). “Lessons in policy implementation from experiences with the Northwest Forest Plan, USA.” Biodiversity and Conservation 23(14): 3607-3613.
Approximately 20 years ago, the preeminent goal for management of the federal forests of the Pacific Northwest shifted suddenly and permanently from sustained timber harvest to conservation of biodiversity and ecological processes, following a series of court cases over protection of species in decline that were associated with old forests. While old growth harvest has largely ceased, some key species are still in decline and forest management has been restricted more than intended. Creation of openings, even those based on disturbance processes, has been especially difficult. Some lessons from this experience include the difficulty of adaptive management, the importance of ecological foundations for management, and the need for stakeholder collaboration. In addition, it is essential to provide society with a vision of ecologically-based forestry, including field demonstrations, and to communicate this approach and its scientific foundation in the popular media.
FULL TEXT LINK: http://dx.doi.org/10.1007/s10531-014-0789-0
Yospin, G. I., S. D. Bridgham, et al. (2014). “A new model to simulate climate-change impacts on forest succession for local land management.” Ecological Applications 25(1): 226-242.
We developed a new climate-sensitive vegetation state-and-transition simulation model (CV-STSM) to simulate future vegetation at a fine spatial grain commensurate with the scales of human land-use decisions, and under the joint influences of changing climate, site productivity, and disturbance. CV-STSM integrates outputs from four different modeling systems. Successional changes in tree species composition and stand structure were represented as transition probabilities and organized into a state-and-transition simulation model. States were characterized based on assessments of both current vegetation and of projected future vegetation from a dynamic global vegetation model (DGVM). State definitions included sufficient detail to support the integration of CV-STSM with an agent-based model of land-use decisions and a mechanistic model of fire behavior and spread. Transition probabilities were parameterized using output from a stand biometric model run across a wide range of site productivities. Biogeographic and biogeochemical projections from the DGVM were used to adjust the transition probabilities to account for the impacts of climate change on site productivity and potential vegetation type. We conducted experimental simulations in the Willamette Valley, Oregon, USA. Our simulation landscape incorporated detailed new assessments of critically imperiled Oregon white oak (Quercus garryana) savanna and prairie habitats among the suite of existing and future vegetation types. The experimental design fully crossed four future climate scenarios with three disturbance scenarios. CV-STSM showed strong interactions between climate and disturbance scenarios. All disturbance scenarios increased the abundance of oak savanna habitat, but an interaction between the most intense disturbance and climate-change scenarios also increased the abundance of subtropical tree species. Even so, subtropical tree species were far less abundant at the end of simulations in CV-STSM than in the dynamic global vegetation model simulations. Our results indicate that dynamic global vegetation models may overestimate future rates of vegetation change, especially in the absence of stand-replacing disturbances. Modeling tools such as CV-STSM that simulate rates and direction of vegetation change affected by interactions and feedbacks between climate and land-use change can help policy makers, land managers, and society as a whole develop effective plans to adapt to rapidly changing climate.
FULL TEXT LINK: http://dx.doi.org/10.1890/13-0906.1
Lookingbill, T. R., E. S. Minor, et al. (2014). “Incorporating Risk of Reinvasion to Prioritize Sites for Invasive Species Management.” Natural Areas Journal 34(3): 268-281.
The relationship between landscape pattern and the distribution and spread of exotic species is an important determinant of where and when management actions are best applied. We have developed an interdisciplinary approach for prioritizing treatment of harmful, nonnative, invasive plants in National Park landscapes of the Mid-Atlantic USA. The approach relies upon a detailed model of reinvasion risk that combines information on: (1) global factors representing park-level infestation from seed and sprout, (2) landscape factors including disturbance-based spread vectors and neighborhood seed density, and (3) local factors determining establishment probability based on habitat suitability. Global seed rain estimates are derived empirically from park inventory data and modified by information on species reproductive strategies. Landscape-level propagule pressure is modeled spatially using species life history characteristics including dispersal attributes, connectivity to nearby plant populations, and increased propagule pressure through disturbance. The local-scale habitat suitability model uses a Mahalanobis distance approach, parameterized from plant inventory plot data and GIS-based data on plot wetness, land cover, slope, radiation, and soil characteristics. We illustrate the model for Ailanthus altissima (tree-of-heaven) in Antietam National Battlefield Park. The results of the A. altissima modeling highlight regions of the park where eradication would be most prudent and feasible based on current infestation patterns and landscape heterogeneity. Although the success of different treatment modalities is often considered in invasive species management, a spatially explicit assessment of likely treatment success is rarely undertaken. Our approach provides a valuable tool to assist natural resource practitioners to prioritize management options in confronting biological invasions.
FULL TEXT LINK: http://dx.doi.org/10.3375/043.034.0303