Fire Treatment Effects on Vegetation Structure, Fuels, and Potential Fire Severity in Western US Forests

Forest structure and species composition in many western U. S. coniferous forests have been altered through. re exclusion, past and ongoing harvesting practices, and livestock grazing over the 20th century. The effects of these activities have been most pronounced in seasonally dry, low and mid-elevation coniferous forests that once experienced frequent, low to moderate intensity,. re regimes. In this paper, we report the effects of Fire and Fire Surrogate (FFS) forest stand treatments on fuel load profiles, potential fire behavior, and fire severity under three weather scenarios from six western U. S. FFS sites. This replicated, multisite experiment provides a framework for drawing broad generalizations about the effectiveness of prescribed. re and mechanical treatments on surface fuel loads, forest structure, and potential. re severity. Mechanical treatments without. re resulted in combined 1-, 10-, and 100-hour surface fuel loads that were significantly greater than controls at three of five FFS sites. Canopy cover was significantly lower than controls at three of five FFS sites with mechanical-only treatments and at all five FFS sites with the mechanical plus burning treatment;. re-only treatments reduced canopy cover at only one site. For the combined treatment of mechanical plus. re, all five FFS sites with this treatment had a substantially lower likelihood of passive crown. re as indicated by the very high torching indices. FFS sites that experienced significant increases in 1-, 10-, and 100-hour combined surface fuel loads utilized harvest systems that left all activity fuels within experimental units. When mechanical treatments were followed by prescribed burning or pile burning, they were the most effective treatment for reducing crown fire potential and predicted tree mortality because of low surface fuel loads and increased vertical and horizontal canopy separation. Results indicate that mechanical plus fire, fire-only, and mechanical-only treatments using whole-tree harvest systems were all effective at reducing potential. re severity under severe. re weather conditions. Retaining the largest trees within stands also increased. re resistance

A prioritization protocol for coastal wetland restoration on Molokaʻi, Hawaiʻi

Hawaiian coastal wetlands provide important habitat for federally endangered waterbirds and socio-cultural resources for Native Hawaiians. Currently, Hawaiian coastal wetlands are degraded by development, sedimentation, and invasive species and, thus, require restoration. Little is known about their original structure and function due to the large-scale alteration of the lowland landscape since European contact. Here, we used 1) rapid field assessments of hydrology, vegetation, soils, and birds, 2) a comprehensive analysis of endangered bird habitat value, 3) site spatial characteristics, 4) sea-level rise projections for 2050 and 2100 and wetland migration potential, and 5) preferences of the Native Hawaiian community in a GIS site suitability analysis to prioritize restoration of coastal wetlands on the island of Molokaʻi. The site suitability analysis is the first, to our knowledge, to incorporate community preferences, habitat criteria for endangered waterbirds, and sea-level rise into prioritizing wetland sites for restoration. The rapid assessments showed that groundwater is a ubiquitous water source for coastal wetlands. A groundwater-fed, freshwater herbaceous peatland or “coastal fen” not previously described in Hawaiʻi was found adjacent to the coastline at a site being used to grow taro, a staple crop for Native Hawaiians. In traditional ecological knowledge, such a groundwater-fed, agro-ecological system is referred to as a loʻipūnāwai (spring pond). Overall, 39 plant species were found at the 12 sites; 26 of these were wetland species and 11 were native. Soil texture in the wetlands ranged from loamy sands to silt and silty clays and the mean % organic carbon content was 10.93% ± 12.24 (sd). In total, 79 federally endangered waterbirds, 13 Hawaiian coots (‘alae keʻokeʻo; Fulica alai) and 66 Hawaiian stilts (aeʻo; Himantopus mexicanus knudseni), were counted during the rapid field assessments. The site suitability analysis consistently ranked three sites the highest, Kaupapaloʻi o Kaʻamola, Kakahaiʻa National Wildlife Refuge, and ʻŌhiʻapilo Pond, under three different weighting approaches. Site prioritization represents both an actionable plan for coastal wetland restoration and an alternative protocol for restoration decision-making in places such as Hawaiʻi where no pristine “reference” sites exist for comparison

Prior consumption of a fat meal in healthy adults modulates the brain’s response to fat

Background: Consumption of fat is regulated by reward and homeostatic pathways, but no studies have examined the role of the intake of a high fat meal (HFM) on subsequent brain activation to oral stimuli. Objective: We evaluated how prior consumption of a HFM or water load (WL) modulates reward, homeostatic and taste brain responses to subsequent delivery of oral fat. Methods: A randomized 2-way crossover design (1-week apart) was used to compare prior consumption of a 250mL HFM (520kcal) (rapeseed oil (440kcal), emulsifier, sucrose, flavor cocktail) or non-caloric WL on brain activation to the delivery of repeated trials of an oral flavored no-fat control stimulus (CS) or flavored fat stimulus (FS) in 17 healthy adults (11 male, age=25±2 years, BMI=22.4±0.8kg/m2). Analyses tested differences in brain activation to the CS and FS, and baseline cerebral blood flow (CBF), following the HFM and WL. Individual’s plasma cholecystokinin (CCK) concentration following the HFM was correlated with their BOLD activation. Results: Prior consumption of the HFM compared to the WL led to decreased anterior insula taste activation in response to both the CS (36.3%,P<0.05) and FS (26.5%,P<0.05). The HFM caused reduced amygdala activation (25.1%,P<0.01) in response to the FS compared to the CS (fat-related satiety). Baseline CBF significantly reduced in taste (insula (5.7%,P<0.01)), homeostatic (hypothalamus (9.2%,P<0.01), thalamus (5.1%,P<0.05))), and reward areas (striatum (9.2%,P<0.01)) following the HFM. Individual’s plasma CCK concentration negatively correlated with brain activation in taste, oral somatosensory and reward areas. Conclusions: To reduce obesity, policy in industry is to lower the fat content of foods. Our results in healthy adults show that a HFM suppresses BOLD activation in taste and reward areas compared to a WL. This understanding will help inform the reformulation of reduced-fat foods that mimic the brain’s response to high fat counterparts, and guide future interventions to reduce obesity

Ecological effects of alternative fuel-reduction treatments: highlights of the National Fire and Fire Surrogate study (FFS)

The 12-site National Fire and Fire Surrogate study (FFS) was a multivariate experiment that evaluated ecological consequences of alternative fuel-reduction treatments in seasonally dry forests of the US. Each site was a replicated experiment with a common design that compared an un-manipulated control, prescribed fire, mechanical and mechanical + fire treatments. Variables within the vegetation, fuelbed, forest floor and soil, bark beetles, tree diseases and wildlife were measured in 10-ha stands, and ecological response was compared among treatments at the site level, and across sites, to better understand the influence of differential site conditions. For most sites, treated stands were predicted to be more resilient to wildfire if it occurred shortly after treatment, but for most ecological variables, short-term response to treatments was subtle and transient. Strong site-specificity was observed in the response of most ecosystem variables, suggesting that practitioners employ adaptive management at the local scale. Because ecosystem components were tightly linked, adaptive management would need to include monitoring of a carefully chosen set of key variables. Mechanical treatments did not serve as surrogates for fire for most variables, suggesting that fire be maintained whenever possible. Restoration to pre-settlement conditions will require repeated treatments over time, with eastern forests requiring more frequent applications.Keywords: Oak, Prescribed fire, Frequent fire regimes, Pine, Mechanical treatment, Forest thinning, Dry forest management, Seasonally dry forest

Effects of fire rotation interval and overstory type on ambient soil temperatures in ponderosa pine forests in Arizona

Ambient soil temperatures were measured every four weeks from May 1986 to November 1986 at three depths under the organic forest floor in ponderosa pine (Pinus ponderosa Lawson & C. Lawson) forests in three stand types subjected to periodic prescribed burning. Temperatures at the organic layer – soil surface interface in sawtimber stands were higher and more variable than in pole and saplings stands. Temperature variability reached a maximum in the summer and decreased into the fall and early winter. Soil temperature variability decreased as depth below the surface increased. Three years after the low-intensity prescribed burns, soil temperatures in the burned stands were not significantly different from the those in the unburned controls, suggesting that any effect, though none was detected, of the low-intensity prescribed burns on soil temperature and belowground processes affected by temperature is short-lived in these stands.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Prescribed Fire Impacts on Soil Carbon and Nitrogen

From the Proceedings of the 2002 Meetings of the Hydrology Section - Arizona-Nevada Academy of Science - April 6, 2002, Midwestern University, Glendale, ArizonaThis article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact [email protected]