Assessing silvopasture management as a strategy to reduce fuel loads and mitigate wildfire risk.

Managing private forests for wildfire resilience is challenging due to conflicting social, economic, and ecological decisions that may result in an increase of surface fuel loads leading to greater fire risk. Due to fire suppression and a changing climate, land managers in fire-prone regions face an increasing threat of high severity fires. Thus, land managers need fuel treatment options that match their forest types and management objectives. One potential option for producers that graze livestock is silvopasture management, where livestock, forages, and overstory vegetation are carefully managed for co-benefits on the same unit of land. This study compared forest composition and structure, fuel types, and vegetative biomass between silvopasture and non-grazed managed forests in Washington, U.S. We show that silvopasture management results in reductions in grass biomass, litter, and duff depth when compared to non-grazed managed forest. These findings point to the integrated nature of silvopasture, where management of overstory composition and structure, understory vegetation, and grazing can reduce fuel loads and potential wildfire risk.

Latitudinal patterns in stabilizing density dependence of forest communities.

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

Evidence for pre-climacteric activation of AOX transcription during cold-induced conditioning to ripen in European pear (Pyrus communis L.).

European pears (Pyrus communis L.) require a range of cold-temperature exposure to induce ethylene biosynthesis and fruit ripening. Physiological and hormonal responses to cold temperature storage in pear have been well characterized, but the molecular underpinnings of these phenomena remain unclear. An established low-temperature conditioning model was used to induce ripening of 'D'Anjou' and 'Bartlett' pear cultivars and quantify the expression of key genes representing ripening-related metabolic pathways in comparison to non-conditioned fruit. Physiological indicators of pear ripening were recorded, and fruit peel tissue sampled in parallel, during the cold-conditioning and ripening time-course experiment to correlate gene expression to ontogeny. Two complementary approaches, Nonparametric Multi-Dimensional Scaling and efficiency-corrected 2-(ΔΔCt), were used to identify genes exhibiting the most variability in expression. Interestingly, the enhanced alternative oxidase (AOX) transcript abundance at the pre-climacteric stage in 'Bartlett' and 'D'Anjou' at the peak of the conditioning treatments suggests that AOX may play a key and a novel role in the achievement of ripening competency. There were indications that cold-sensing and signaling elements from ABA and auxin pathways modulate the S1-S2 ethylene transition in European pears, and that the S1-S2 ethylene biosynthesis transition is more pronounced in 'Bartlett' as compared to 'D'Anjou' pear. This information has implications in preventing post-harvest losses of this important crop.

Fixing a snag in carbon emissions estimates from wildfires.

Wildfire is an essential earth-system process, impacting ecosystem processes and the carbon cycle. Forest fires are becoming more frequent and severe, yet gaps exist in the modeling of fire on vegetation and carbon dynamics. Strategies for reducing carbon dioxide (CO2 ) emissions from wildfires include increasing tree harvest, largely based on the public assumption that fires burn live forests to the ground, despite observations indicating that less than 5% of mature tree biomass is actually consumed. This misconception is also reflected though excessive combustion of live trees in models. Here, we show that regional emissions estimates using widely implemented combustion coefficients are 59%-83% higher than emissions based on field observations. Using unique field datasets from before and after wildfires and an improved ecosystem model, we provide strong evidence that these large overestimates can be reduced by using realistic biomass combustion factors and by accurately quantifying biomass in standing dead trees that decompose over decades to centuries after fire ("snags"). Most model development focuses on area burned; our results reveal that accurately representing combustion is also essential for quantifying fire impacts on ecosystems. Using our improvements, we find that western US forest fires have emitted 851 ± 228 Tg CO2 (~half of alternative estimates) over the last 17 years, which is minor compared to 16,200 Tg CO2 from fossil fuels across the region.

Identifying best methods for routine ELISA detection of microcystin in seafood.

Ingestion of water contaminated with the cyanotoxin, microcystin (MC), can pose serious health risks to humans. MC is also known to accumulate in seafood; however, this exposure pathway is much less understood. A fundamental element of this uncertainty is related to analytical difficulties. Commercially available enzyme-linked immunosorbent assays (ELISAs) offer one of the best options for routine MC detection, but methods of detecting MC in tissue are far from standardized. We spiked freshwater finfish and marine mussel tissues with MC, then compared recovery rates using four different preparation protocols and two ELISA types (polyclonal anti-MC-ADDA/direct monoclonal (DM)). Preparation protocol, type of ELISA, and seafood tissue variety significantly affected MC detection. This is the first known study to use DM ELISA for tissue analyses, and our findings demonstrate that DM ELISA combined with a short solvent extraction results in fewer false positives than other commonly used methods. This method can be used for rapid and reliable MC detection in seafood.

Spatial aspects of tree mortality strongly differ between young and old-growth forests.

Rates and spatial patterns of tree mortality are predicted to change during forest structural development. In young forests, mortality should be primarily density dependent due to competition for light, leading to an increasingly spatially uniform pattern of surviving trees. In contrast, mortality in old-growth forests should be primarily caused by contagious and spatially autocorrelated agents (e.g., insects, wind), causing spatial aggregation of surviving trees to increase through time. We tested these predictions by contrasting a three-decade record of tree mortality from replicated mapped permanent plots located in young (< 60-year-old) and old-growth (> 300-year-old) Abies amabilis forests. Trees in young forests died at a rate of 4.42% per year, whereas trees in old-growth forests died at 0.60% per year. Tree mortality in young forests was significantly aggregated, strongly density dependent, and caused live tree patterns to become more uniform through time. Mortality in old-growth forests was spatially aggregated, but was density independent and did not change the spatial pattern of surviving trees. These results extend current theory by demonstrating that density-dependent competitive mortality leading to increasingly uniform tree spacing in young forests ultimately transitions late in succession to a more diverse tree mortality regime that maintains spatial heterogeneity through time.

Spatially nonrandom tree mortality and ingrowth maintain equilibrium pattern in an old-growth Pseudotsuga-Tsuga forest.

Mortality processes in old-growth forests are generally assumed to be driven by gap-scale disturbance, with only a limited role ascribed to density-dependent mortality, but these assumptions are rarely tested with data sets incorporating repeated measurements. Using a 12-ha spatially explicit plot censused 13 years apart in an approximately 500-year-old Pseudotsuga-Tsuga forest, we demonstrate significant density-dependent mortality and spatially aggregated tree recruitment. However, the combined effect of these strongly nonrandom demographic processes was to maintain tree patterns in a state of dynamic equilibrium. Density-dependent mortality was most pronounced for the dominant late-successional species, Tsuga heterophylla. The long-lived, early-seral Pseudotsuga menziesii experienced an annual stem mortality rate of 0.84% and no new recruitment. Late-seral species Tsuga and Abies amabilis had nearly balanced demographic rates of ingrowth and mortality. The 2.34% mortality rate for Taxus brevifolia was higher than expected, notably less than ingrowth, and strongly affected by proximity to Tsuga. Large-diameter Tsuga structured both the regenerating conspecific and heterospecific cohorts with recruitment of Tsuga and Abies unlikely in neighborhoods crowded with large-diameter competitors (P < 0.001). Density-dependent competitive interactions strongly shape forest communities even five centuries after stand initiation, underscoring the dynamic nature of even equilibrial old-growth forests.

The importance of large-diameter trees to forest structural heterogeneity.

Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥ 1 cm dbh, all 1,966 snags ≥ 10 cm dbh, and all shrub patches ≥ 2 m(2). Basal area of the 26 woody species was 62.18 m(2)/ha, of which 61.60 m(2)/ha was trees and 0.58 m(2)/ha was tall shrubs. Large-diameter trees (≥ 100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P ≤ 0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses.

Effects of remedial sport hunting on cougar complaints and livestock depredations.

Remedial sport hunting of predators is often used to reduce predator populations and associated complaints and livestock depredations. We assessed the effects of remedial sport hunting on reducing cougar complaints and livestock depredations in Washington from 2005 to 2010 (6 years). The number of complaints, livestock depredations, cougars harvested, estimated cougar populations, human population and livestock populations were calculated for all 39 counties and 136 GMUs (game management units) in Washington. The data was then analyzed using a negative binomial generalized linear model to test for the expected negative relationship between the number of complaints and depredations in the current year with the number of cougars harvested the previous year. As expected, we found that complaints and depredations were positively associated with human population, livestock population, and cougar population. However, contrary to expectations we found that complaints and depredations were most strongly associated with cougars harvested the previous year. The odds of increased complaints and livestock depredations increased dramatically (36 to 240%) with increased cougar harvest. We suggest that increased young male immigration, social disruption of cougar populations, and associated changes in space use by cougars - caused by increased hunting resulted in the increased complaints and livestock depredations. Widespread indiscriminate hunting does not appear to be an effective preventative and remedial method for reducing predator complaints and livestock depredations.

The natural history of spina bifida in children pilot project: research protocol.

BACKGROUND: Population-based empirical information to inform health care professionals working with children with spina bifida currently is lacking. Spina bifida is a highly complex condition that not only affects mobility but many additional aspects of life. We have developed a pilot project that focuses on a broad range of domains: surgeries, development and learning, nutrition and physical growth, mobility and functioning, general health, and family demographics. Specifically, we will: (1) explore the feasibility of identifying and recruiting participants using different recruitment sources, (2) test a multidisciplinary module to collect the data, (3) determine the utility of different methods of retrieving the data, and (4) summarize descriptive information on living with spina bifida. OBJECTIVE: The overall objective of the project was to provide information for a future multistate prospective study on the natural history of spina bifida. METHODS: Families with a child 3 to 6 years of age with a diagnosis of spina bifida were eligible for enrollment. Eligible families were identified through a US population-based tracking system for birth defects and from a local spina bifida clinic. RESULTS: This is an ongoing project with first results expected in 2013. CONCLUSIONS: This project, and the planned multistate follow-up project, will provide information both to health care professionals experienced in providing care to patients with spina bifida, and to those who have yet to work with this population. The long-term purpose of this project is to increase the knowledge about growing up with spina bifida and to guide health care practices by prospectively studying a cohort of children born with this condition.

Health risk behaviors among young adults with spina bifida.

AIM: Persons with spina bifida who adopt unhealthy lifestyles could be at increased risk of adverse health outcomes because the presence of spina bifida may magnify this risk. We estimated overall and age-specific prevalence of selected health risk behaviors (HRBs) in young people with spina bifida and examined the association between HRBs and depression. METHOD: We performed analyses on data obtained from individuals with spina bifida (n=130; mean age 23y SD 4y 5mo; 64 males, 66 females; 64% lumbosacral lesion; 77% with shunt) who participated in a population-based survey conducted by the Arkansas Spinal Cord Commission in 2005. RESULTS: Compared with national estimates, young people with spina bifida tend to eat less healthy diets, do less exercise, and engage in more sedentary activities. Respondents were less likely to use substances (alcohol, tobacco, illegal drugs), which peaked among 25 to 31 year olds. About 90% saw a doctor in the previous year. Nearly one half reported mild or major depressive symptoms. In the logistic regression analysis after controlling for potential confounders (age, sex, ethnic group, education, employment, marital status, living arrangement, level of lesion, presence of shunt, mobility, self-rated health and healthcare utilization), major depressive symptoms were associated with current alcohol drinking (adjusted odds ratio: 4.74; 95% CI 1.18-19.04). INTERPRETATION: Young adults with spina bifida exhibit unhealthy behaviors that continue into their late 20s. The findings highlight the need to increase awareness of their health risk profiles in the spina bifida community and show opportunities for mental health and health risk screening and counseling by healthcare providers.

Ecological importance of large-diameter trees in a temperate mixed-conifer forest.

Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m(2). We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by a few large trees as opposed to many smaller trees.

Evaluating integrated watershed management using multiple criteria analysis--a case study at Chittagong Hill Tracts in Bangladesh.

Criteria and indicators assessment is one of the ways to evaluate management strategies for mountain watersheds. One framework for this, Integrated Watershed Management (IWM), was employed at Chittagong Hill Tracts region of Bangladesh using a multi-criteria analysis approach. The IWM framework, consisting of the design and application of principles, criteria, indicators, and verifiers (PCIV), facilitates active participation by diverse professionals, experts, and interest groups in watershed management, to explicitly address the demands and problems to measure the complexity of problems in a transparent and understandable way. Management alternatives are developed to fulfill every key component of IWM considering the developed PCIV set and current situation of the study area. Different management strategies, each focusing on a different approach (biodiversity conservation, flood control, soil and water quality conservation, indigenous knowledge conservation, income generation, watershed conservation, and landscape conservation) were assessed qualitatively on their potential to improve the current situation according to each verifier of the criteria and indicator set. Analytic Hierarchy Process (AHP), including sensitivity analysis, was employed to identify an appropriate management strategy according to overall priorities (i.e., different weights of each principle) of key informants. The AHP process indicated that a strategy focused on conservation of biodiversity provided the best option to address watershed-related challenges in the Chittagong Hill Tracts, Bangladesh.

Disability among individuals with sickle cell disease: literature review from a public health perspective.

CONTEXT: Young people with blood disorders face challenges in maintaining their physical health as they age. Sickle cell disease has well-documented complications in various organ systems. Increasingly, professionals, consumers, and advocates involved in blood disorders are concerned about the cumulative and ongoing effect of organ-specific complications on function and participation. EVIDENCE ACQUISITION: Publications were identified that looked at the relationship between sickle cell disease and associated impairments and restrictions in participation as defined by the International Classification of Function, Disability, and Health (ICF). EVIDENCE SYNTHESIS: This article organizes a literature review in PubMed using ICF terms that define functional limitations and participation restrictions in sickle cell disease. CONCLUSIONS: Individuals with sickle cell disease experience complications in multiple organ systems that affect related functions and, consequently, participation in community living. The effects begin early in childhood and accumulate across the life course into adulthood. Intervention research is needed to understand how contextual factors can promote optimal function and participation in the face of mounting impairments.

Health disparities in low-income families with infants and toddlers: needs and challenges related to disability.

This study examines disparities in health status, health care utilization, insurance coverage and satisfaction in US low-income parents of infants and toddlers with disabilities compared to low-income parents of children without disabilities. The Early Head Start Research and Evaluation Project is a longitudinal study involving 2087 families in 17 communities across the United States. Families completed interviews at enrollment and at 7, 16, and 28 months after enrollment. Descriptive analyses were conducted to characterize children's status in terms of health, health care use, and insurance coverage. Children with disabilities were more likely to experience poor health and to use more health care services. Parents of children with disabilities were more likely to report that medical care was inadequate. Hispanic children were less likely to experience excellent health. Hispanic parents were less likely to have health insurance or to report that their medical care was adequate. Low-income parents of young children with disabilities perceived their children as less healthy, more vulnerable and needing more health services. This study demonstrates the importance of providing accessible, culturally-competent services to this vulnerable population.

Need for the life course model for spina bifida.

Because children with chronic conditions, such as spina bifida, have grown up into adults in increasing numbers, they and their families have increasingly questioned whether they have reached their full potential and maximized their participation in adult activities. Lack of knowledgeable adult medical providers and longitudinal data about natural history places more responsibility on individuals and their family for self-care of the impairment. This article describes the need for the life course model, which merges several concepts and principles related to children with disabilities and provides a framework for services and research to achieve the desired adult outcomes.

Physiatrists and developmental pediatricians working together to improve outcomes in children with spina bifida.

Based on the experience of 2 physicians from physiatry and developmental pediatrics, this article proposes a framework for improving care and outcomes for children with spina bifida. The combined skills of physiatrists and developmental pediatricians, along with other disciplines, can form the ideal team to manage the complex issues faced by this population. The developmental pediatrician is best suited for directing care for younger children through the elementary and middle school years, during which time behavioral and educational issues are prominent. As the child assumes more responsibility for self-management in adolescence, the physiatrist is ideally suited to provide major clinical input that improves functional outcomes. The addition of the discipline of physiatry to traditional, developmentally oriented pediatric interdisciplinary teams can add the much needed dimensions of activity and participation, and improve functional outcomes at the adult level by encouraging activities in adolescence that lead to full participation in adulthood.