Effects of Rock Climbing on Populations of Presettlement Eastern White Cedar (Thuja occidentalis) on Cliffs of the Niagara Escarpment, Canada

Cliffs of the Niagara Escarpment support a self-sustaining presettlement forest of eastern white cedar (  Thuja occidentalis L.) in which some trees are over 1000 years old. Many of the cliffs are also popular locations for recreational rock climbing. Our study employed a stratified random sampling design to assess the impact of rock climbing on populations of cliff-face and cliff-edge trees. Tree density and age structure were compared between four climbed and three unclimbed sites in the vicinity of Milton, Ontario. Signs of physical damage were also recorded for the trees sampled at each site. The results showed that living tree density on the cliff face was lower in climbed areas. The age structures of these forests showed that the numbers of older and younger age classes have been reduced on climbed cliff faces compared with unclimbed areas. A high percentage of trees on climbed cliff faces showed evidence of damage by humans. These trends were not as apparent on cliff edges where other disturbances have affected age structure. We recommend that cliff faces be explored for the presence of presettlement forest and that recreation managers of lands with exposed cliff faces incorporate rock climbing considerations into their management plans. Monitoring programs would help track levels of disturbance. Education of the climbing community would be the most effective long-term solution to limiting disturbance in sensitive areas.     

Feeding and nutritional ecology of the sea urchin strongylocentrotus drobachiensis in Maine,USA

The sea urchin strongylocentrotus drobachiensis exhibited a high degree of food selectivity, whether foods were presented singly or in combination. Foods ranked from most to least preferred were, in summer, Laminaria longicruris, Chondrus crispus, Corallina officinalis, Ascophyllum nodosum, and Agarum cribrosum, whereas in winter A. nodosum and A. cribrosum exchanged ranks. Food preference was not correlated with caloric content but, because of higher feeding rates on preferred foods, caloric intake was positively correlated with preference. Similarly, food absorption rankings were not correlated with food preference, with the exception of gravimetric efficiencies in winter. However, the absorption of L. longicruris, the most preferred alga, was highest in all measurements. Growth and reproductive development of S. drobachiensis on single species diets were positively correlated with food preference. Highest values occurred with animals fed L. longicruris. Urchins transferred from non-preferred to preferred diets showed increased somatic and reproductive growth compared to control animals on the original, non-preferred diets. Conversely, when transferred from preferred to non-preferred diets, urchins showed reduced growth compared to controls. No combination diet tested supported significantly better gonadal growth than L. longicruris: 25% C. crispus supported slightly better somatic growth than L. longicruris alone. These data support the view that S. drobachiensis has evolved a feeding strategy resulting in the maximization of growth and reproduction.     

Spatial and temporal trends of precipitation chemistry in the United States, 1985-2002

A Seasonal Kendall Trend (SKT) test was applied to precipitation-weighted concentration data from 164 National Atmospheric Deposition Program National Trends Network (NADP/NTN) sites operational from 1985 to 2002. Analyses were performed on concentrations of ammonium, sulfate, nitrate, dissolved inorganic nitrogen (DIN, sum of nitrogen from nitrate and ammonium), and earth crustal cations (ECC, sum of calcium, magnesium, and potassium). Over the 18-year period, statistically significant (p< or =0.10) increases in ammonium concentrations occurred at 93 sites (58%), while just three sites had statistically significant ammonium decreases. Central and northern Midwestern states had the largest ammonium increases. The generally higher ammonium concentrations were accompanied by significant sulfate decreases (139 sites, 85%), and only one significant increase which occurred in Texas. In the west central United States there were significant nitrate increases (45 sites, 27%), while in the northeastern United States there were significant decreases (25 sites, 15%). Significant DIN decreases were observed in the northeastern United States (11 sites, 7%); elsewhere there were significant increases at 75 sites (46%). ECC decreased significantly at 65 sites (40%), predominantly in the central and southern United States, and increased at 11 sites (7%). The concentrations of sulfate, nitrate, and ammonium in precipitation have changed markedly over the time period studied. Such trends indicate changes in the mix of gases and particles scavenged by precipitation, possibly reflecting changes in emissions, atmospheric chemical transformations, and weather patterns.     

Surfactant-assisted UV-photolysis of nitroarenes

Photochemical transformations (lambda-254 nm) of 2,4-dinitrotoluene (2,4-DNT) in aqueous solutions containing the cationic surfactant cetyltrimethylammonium (CTA) and the anionic nucleophile borohydride (BH4-) were investigated. The overall decay rate was enhanced at CTA concentrations above the critical micelle concentration (cmc) when stoichiometric excess BH4- was present in solution. A kinetic model that separates the overall reaction rate into micellar and aqueous pseudo-phase components indicates transformation in micelles is 17 times faster that in the homogeneous water phase under those conditions investigated. Intermediate products were identified by comparing the HPLC retention times and ultraviolet-visible absorption spectra of product peaks to those of analytical standards. 2-Methyl-5-nitroaniline, 4-nitrotoluene, 2-nitrotoluene, 4-methyl-3-nitroaniline, 2,4-diaminotoluene, o-toluidine, 1,3-dinitrobenzene, 3-nitroaniline, p-cresol, and 2,4-diaminophenol were identified as photo-transformation intermediates or products.     

Serum concentrations of perfluorooctanesulfonate and other fluorochemicals in an elderly population from Seattle, Washington

Perfluorooctanesulfonyl fluoride (POSF, C₈F₁₇SO₂F) related-materials have been used as surfactants, paper and packaging treatments, and surface (e.g., carpet, textile, upholstery) protectants. A metabolite, perfluorooctanesulfonate (PFOS, C₈F₁₇SO₃⁻), has been identified in the serum and liver of non-occupationally exposed humans and wildlife. Because of its persistence, an important question was whether elderly humans might have higher PFOS concentrations. From a prospective study designed to examine cognitive function in the Seattle (WA) metropolitan area, blood samples were collected from 238 dementia-free subjects (ages 65–96). High-pressure liquid chromatography-electrospray tandem mass spectrometry determined seven fluorochemicals: PFOS; N-ethyl perfluorooctanesulfonamidoacetate; N-methyl perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamide; perfluorooctanoate; and perfluorohexanesulfonate. Serum PFOS concentrations ranged from less than the lower limit of quantitation (3.4 ppb) to 175.0 ppb (geometric mean 31.0 ppb; 95% CI 28.8–33.4). An estimate of the 95% tolerance limit was 84.1 ppb (upper 95% confidence limit 104.0 ppb). Serum PFOS concentrations were slightly lower among the most elderly. There were no significant differences by sex or years residence in Seattle. The distributions of the other fluorochemicals were approximately an order of magnitude lower. Similar to other reported findings of younger adults, the geometric mean serum PFOS concentration in non-occupational adult populations likely approximates 30–40 ppb with 95% of the population’s serum PFOS concentrations below 100 ppb.     

Psychological drivers of risk-reducing behaviors to limit human–wildlife conflict

Conflicts between people and wild animals are increasing globally, often with serious consequences for both. Local regulations or ordinances are frequently used to promote human behaviors that minimize these conflicts (risk-reducing behaviors), but compliance with ordinances can be highly variable. While efforts to increase compliance could be improved through applications of conservation psychology, little is known about the relative influence of different factors motivating compliance. Using concepts from psychology and risk theory, we conducted a longitudinal study pairing data from mail surveys with direct observations of compliance with a wildlife ordinance requiring residents to secure residential garbage from black bears (Ursus americanus). We assessed the relative influence of beliefs and attitudes toward bears and bear proofing, perceived behavioral control, perceived risks and benefits assigned to bears, norms, trust in management, previous experience with conflicts, and demographics on compliance behavior (i.e., bear proofing). Data on previous experience were obtained through direct observation and survey reports. We found that higher compliance rates were associated with more observed conflicts on a respondent's block. Counter to expectations, however, residents were less compliant when they were more trusting of the management agency and perceived more benefits from bears. We suggest that messages have the potential to increase compliance when they empower residents by linking successful management of conflicts to individual actions and emphasize how reducing conflicts could maintain benefits provided by wildlife. Modifying existing educational materials to account for these psychological considerations and evaluating their impact on compliance behavior over time are important next steps in changing human behaviors relevant to the globally important problem of human-wildlife conflict.     

Inverse modeling for effective dispersal: Do we need tree size to estimate fecundity?

The estimation of the dispersal kernel for the seedling and sapling stages of the recruitment process was made possible through the application of inverse modeling to dispersal data. This method uses the spatial coordinates of adult trees and the counts of seedlings (or saplings) in small quadrats to estimate the dispersal kernel. The unknown number of recruits produced by an adult tree (the fecundity) is estimated - simultaneously with the dispersal kernel - via an allometric linear model relating the unknown quantity with a (easily) measured characteristic of the adult tree (usually the basal area). However, the allometric relation between tree size and reproductive success in the sapling (or seedling) stage may not be strong enough when numerous, well-documented, post-dispersal processes (such as safe-site limitation for recruitment) cause large post-dispersal seedling mortality, which is usually unrelated to the size of the tree that dispersed them. In this paper we hypothesize that when tree size and reproductive success in the seedling/sapling stage are not well correlated then the use of allometry in inverse modeling is counter-productive and may lead to poor model fits. For these special cases we suggest using a new model for effective dispersal that we term the unrestricted fecundity (UF) model that, contrary to allometric models, makes no assumptions on the fecundities; instead they are allowed to vary freely from one tree to another and even to be zero for trees that are reproductively inactive. Based on this model, we examine the hypothesis that when tree size and reproductive success are weakly correlated and the fecundities are estimated independently of tree size the goodness-of-fit and the ecological meaning of dispersal models (in the seedling or sapling stage) may be enhanced. Parameters of the UF model are estimated through the EM algorithm and their standard errors are approximated via the observed information matrix. We fit the UF model to a dataset from an expanding European beech population of central Spain as well as to a set of simulated dispersal data were the correlation between reproductive success and tree size was moderate. In comparisons with a simple allometric model, the UF model fitted the data better and the parameter estimates were less biased. We suggest using this new approach for modeling dispersal in the seedling and sapling stages when tree size (or other adult-specific covariates) is not deemed to be in strong relation to the reproductive success of adults. Models that use covariates for modeling the fecundity of adults should be preferred when reproductive success and tree size guard a strong relationship.