Compilation by Robyn Darbyshire
Nielsen-Pincus, M., R. G. Ribe, et al. (2015). “Spatially and socially segmenting private landowner motivations, properties, and management: A typology for the wildland urban interface.” Landscape and Urban Planning 137: 1-12.
Throughout North America, rapid exurban development is increasing the spatial extent and population density of the wildland urban interface (WUI), exacerbating problems of wildfire risk and biodiversity loss. To address these issues, policy and planning tools need to be targeted toward different types of WUI landowners in the different types of landscape locations they occupy. We developed a typology of WUI landowners in the Willamette Valley foothills of Oregon, USA. We used market segmentation techniques on mail survey data (n = 939) to develop a typology of four types of WUI landowners in the Willamette Valley foothills of Oregon, USA. We identify differences in each type’s land management strategies and property characteristics and use commonly available GIS data to project where different landowner types are likely to occur in the landscape. We conclude with a discussion of the importance of social and spatial heterogeneity in the WUI for strategically targeted policy and planning efforts intended to manage wildfire risk and promote ecological restoration.
Wagenbrenner, J. W. and P. R. Robichaud (2014). “Post-fire bedload sediment delivery across spatial scales in the interior western United States.” Earth Surface Processes and Landforms 39(7): 865-876.
Post-fire sediment yields can be up to three orders of magnitude greater than sediment yields in unburned forests. Much of the research on post-fire erosion rates has been at small scales (100 m2 or less), and post-fire sediment delivery rates across spatial scales have not been quantified in detail. We developed relationships for post-fire bedload sediment delivery rates for spatial scales up to 117 ha using sediment yield data from six published studies and two recently established study sites. Sediment yields and sediment delivery ratios (SDRs; sediment delivered at the catchment scale divided by the sediment delivered from a plot nested within the catchment) were related to site factors including rainfall characteristics, area, length, and ground cover. Unit-area sediment yields significantly decreased with increasing area in five of the six sites. The annual SDRs ranged from 0.0089 to 1.15 and these were more closely related to the ratio of the plot lengths than the ratio of plot areas. The developed statistical relationships will help quantify post-fire sediment delivery rates across spatial scales in the interior western United States and develop process-based scaling relationships.
FULL TEXT LINK: http://dx.doi.org/10.1002/esp.3488
Beschta, R. L., J. Boone Kauffman, et al. (2014). “Long-term livestock grazing alters aspen age structure in the northwestern Great Basin.” Forest Ecology and Management 329: 30-36.
We determined the age structure of quaking aspen (Populus tremuloides) over the period 1850–2009 in Hart Mountain National Antelope Refuge riparian areas to evaluate potential influences of (a) livestock herbivory and (b) climate on aspen demography. We found a significant decline in aspen recruitment (p < 0.05) in the late 1800s, coincident with the onset of high levels of Euro-American livestock grazing. Although livestock use was regulated following establishment of the refuge in 1936, low levels of aspen recruitment continued. After termination of livestock grazing in 1990, aspen recruitment on the refuge increased (p < 0.05) by more than an order of magnitude in comparison to levels occurring during the previous half-century of regulated grazing. Climate variables (i.e., Palmer Drought Severity Index, annual precipitation, and annual temperature) appeared to have little influence on long-term patterns of aspen recruitment. Overall, results are consistent with top–down forcing by livestock herbivory as the major factor associated with a century of reduced aspen recruitment on HMNAR. Where long-term declines in aspen are currently underway on grazed lands in the western US, land managers need to carefully consider the potential effects of livestock and alter, as needed, management of these ungulates to ensure retention of aspen woodlands and their ecosystem services.
Jenkins, M. E., T. L. Bell, et al. (2014). “Pyrogenic carbon: the influence of particle size and chemical composition on soil carbon release.” International Journal of Wildland Fire 23(7): 1027-1033.
In many countries, prescribed or planned burning is increasingly used as a management strategy to reduce the risk and negative effects of wildfires. As a by-product of this practice, ash, charcoal and partially charred material (referred to here as pyrogenic carbon, PC) is created. The amount and type of PC produced and fate of this form of carbon is uncertain. PC is often assumed to be resistant to chemical and microbial degradation and therefore potentially persistent in soils for hundreds or thousands of years. As a result, PC has been proposed as a sink for carbon and promoted for its storage potential in soil. We hypothesised that the differing components of PC would interact differently with soil processes and have varying potential for carbon storage. We analysed the chemical composition of PC produced by prescribed fire in a eucalypt forest and measured its effect on soil respiration. A laboratory incubation experiment showed that when PC of differing size fractions was added to soil, only the smallest size fraction (<1 mm; ash) increased rates of soil respiration, whereas larger fractions (charcoal) had little effect. The carbon contained in charcoal was resistant to microbial degradation and had little effect on microbial processes such as respiration. In general, fires of greater intensity will produce greater proportional amounts of smaller size particles and will likely result in faster rates of respiration than fires of lesser intensity. Therefore, lower intensity fires may ultimately have a greater capacity for soil carbon sequestration than those of higher intensity.
FULL TEXT LINK: http://www.publish.csiro.au/paper/WF13189
Lefèvre, F., T. Boivin, et al. (2014). “Considering evolutionary processes in adaptive forestry.” Annals of Forest Science 71(7): 723-739.
Managing forests under climate change requires adaptation. The adaptive capacity of forest tree populations is huge but not limitless. Integrating evolutionary considerations into adaptive forestry practice will enhance the capacity of managed forests to respond to climate-driven changes. Focusing on natural regeneration systems, we propose a general framework that can be used in various and complex local situations by forest managers, in combination with their own expertise, to integrate evolutionary considerations into decision making for the emergence of an evolution-oriented forestry. We develop a simple process-based analytical grid, using few processes and parameters, to analyse the impact of forestry practice on the evolution and evolvability of tree populations. We review qualitative and, whenever possible, quantitative expectations on the intensity of evolutionary drivers in forest trees. Then, we review the effects of actual and potential forestry practice on the evolutionary processes. We illustrate the complexity of interactions in two study cases: the evolutionary consequences for forest trees of biotic interactions and of highly heterogeneous environment. Evolution-oriented forestry may contribute adapting forests to climate change. It requires combining short-term and long-term objectives. We propose future lines of research and experimentation.
FULL TEXT LINK: http://dx.doi.org/10.1007/s13595-013-0272-1