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61.
Rebecca J. McLain Patrick T. Hurley Marla R. Emery Melissa R. Poe 《Local Environment》2014,19(2):220-240
Recent “green” planning initiatives envision food production, including urban agriculture and livestock production, as desirable elements of sustainable cities. We use an integrated urban political ecology and human–plant geographies framework to explore how foraging for “wild” foods in cities, a subversive practice that challenges prevailing views about the roles of humans in urban green spaces, has potential to also support sustainability goals. Drawing on research from Baltimore, New York City, Philadelphia, and Seattle, we show that foraging is a vibrant and ongoing practice among diverse urban residents in the USA. At the same time, as reflected in regulations, planning practices, and attitudes of conservation practitioners, it is conceptualised as out of place in urban landscapes and an activity to be discouraged. We discuss how paying attention to urban foraging spaces and practices can strengthen green space planning and summarise opportunities for and challenges associated with including foragers and their concerns. 相似文献
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Hugh S Robinson Robert B Wielgus Hilary S Cooley Skye W Cooley 《Ecological applications》2008,18(4):1028-1037
Carnivores are widely hunted for both sport and population control, especially where they conflict with human interests. It is widely believed that sport hunting is effective in reducing carnivore populations and related human-carnivore conflicts, while maintaining viable populations. However, the way in which carnivore populations respond to harvest can vary greatly depending on their social structure, reproductive strategies, and dispersal patterns. For example, hunted cougar (Puma concolor) populations have shown a great degree of resiliency. Although hunting cougars on a broad geographic scale (> 2000 km2) has reduced densities, hunting of smaller areas (i.e., game management units, < 1000 km2), could conceivably fail because of increased immigration from adjacent source areas. We monitored a heavily hunted population from 2001 to 2006 to test for the effects of hunting at a small scale (< 1000 km2) and to gauge whether population control was achieved (lambda < or = 1.0) or if hunting losses were negated by increased immigration allowing the population to remain stable or increase (lambda > or = 1.0). The observed growth rate of 1.00 was significantly higher than our predicted survival/fecundity growth rates (using a Leslie matrix) of 0.89 (deterministic) and 0.84 (stochastic), with the difference representing an 11-16% annual immigration rate. We observed no decline in density of the total population or the adult population, but a significant decrease in the average age of independent males. We found that the male component of the population was increasing (observed male population growth rate, lambda(OM) = 1.09), masking a decrease in the female component (lambda(OF) = 0.91). Our data support the compensatory immigration sink hypothesis; cougar removal in small game management areas (< 1000 km2) increased immigration and recruitment of younger animals from adjacent areas, resulting in little or no reduction in local cougar densities and a shift in population structure toward younger animals. Hunting in high-quality habitats may create an attractive sink, leading to misinterpretation of population trends and masking population declines in the sink and surrounding source areas. 相似文献
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Octopus dofleini (Walker) is a common inhabitant of shallow subtidal communities in the Northeast Pacific. The abundances of octopuses at two sites monitored since 1977 have fluctuated greatly during this period. The populations reached high abundances in mid-summer and, during some years, mid-winter. The highest abundances at the two sites did not coincide. There was a constant influx of new octopuses into both study sites, with the greatest immigration occurring in early summer. The octopuses captured spanned a wide range of weights every month, with no clear size classes or seasonal trends in size. The weights of newly-captured octopuses, however, did differ between the sexes and seasons: males weighed more on the average than females, and male weight decreased from winter to fall while female weights did not change O. dofleini appeared to recruit throughout the year; the smallest octopuses occurred between May and November and the greatest number of small octopuses was found in July and August in most years. Females predominated at both study sites throughout the year. However, males predominated among octopuses caught in traps at nearby locations, suggesting that the skewed sex ratios were due to behavioral differences between the sexes. 相似文献
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Summary The daily movements and the resulting activity and calling fields are described for three groups of titi monkeys Callicebus moloch. Groups move to the periphery of their home range in the early morning and then call. Playback experiments confirmed that both proximity and location of calling by neighboring animals affect the group's response. Subsequent countercalling often regulates the approach of neighboring groups to a boundary. After encountering adjacent groups, animals return to areas near the home range center. Movements, calling behavior, and the response to neighboring groups all increase the probability of intergroup encounters in the early morning. Encounters define and reinforce the conventional location of boundaries. Boundaries decrease the probability of intergroup encounters at other times and allow exclusive use of space. 相似文献
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Moreno FN Anderson CW Stewart RB Robinson BH 《Environmental pollution (Barking, Essex : 1987)》2005,136(2):341-352
Experiments were carried out in plant growth chambers and in the field to investigate plant-mercury accumulation and volatilisation in the presence of thiosulphate (S2O3)-containing solutions. Brassica juncea (Indian mustard) plants grown in Hg-contaminated Tui mine tailings (New Zealand) were enclosed in gastight volatilisation chambers to investigate the effect of ammonium thiosulphate ([NH4]2 S2O3) on the plant-Hg volatilisation process. Application of (NH4)2 S2O3 to substrates increased up to 6 times the Hg concentration in shoots and roots of B. juncea relative to controls. Volatilisation rates were significantly higher in plants irrigated only with water (control) when compared to plants treated with (NH4)2 S2O3. Volatilisation from barren pots (without plants) indicated that Hg in tailings is subject to biological and photochemical reactions. Addition of sodium thiosulphate (Na2S2O3) at 5 g/kg of substrate to B. juncea plants grown at the Tui mine site confirmed the plant growth chambers studies showing the effectiveness of thio-solutions at enhancing shoot Hg concentrations. Mercury extraction from the field plots yielded a maximum value of 25 g/ha. Mass balance studies revealed that volatilisation is a dominant pathway for Hg removal from the Tui mine site. A preliminary assessment of the risks of volatilisation indicated that enhanced Hg emissions by plants would not harm the local population and the regional environment. 相似文献
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Comparison of particle light scattering and fine particulate matter mass in central California 总被引:2,自引:0,他引:2
Chow JC Watson JG Park K Lowenthal DH Robinson NF Park K Magliano KA 《Journal of the Air & Waste Management Association (1995)》2006,56(4):398-410
Particle light scattering (Bsp) from nephelometers and fine particulate matter (PM2.5) mass determined by filter samplers are compared for summer and winter at 35 locations in and around California's San Joaquin Valley from December 2, 1999 to February 3, 2001. The relationship is described using particle mass scattering efficiency (sigmasp) derived from linear regression of Bsp on PM2.5 that can be applied to estimated PM2.5 from nephelometer data within the 24-hr filter sampling periods and between the every-6th-day sampling frequency. An average of sigmaSp = 4.9 m2/g was found for all of the sites and seasons; however, sigmasp averaged by site type and season provided better PM2.5 estimates. On average, the sigmasp was lower in summer than winter, consistent with lower relative humidities, lower fractions of hygroscopic ammonium nitrate, and higher contributions from fugitive dust. Winter average sigmasp were similar at non-source-dominated sites, ranging from 4.8 m2/g to 5.9 m2/g. The sigmasp was 2.3 m2/g at the roadside, 3.7 m2/g at a dairy farm, and 4.1 m2/g in the Kern County oilfields. Comparison of Bsp from nephelometers with and without a PM2.5 inlet at the Fresno Supersite showed that coarse particles contributed minor amounts to light scattering. This was confirmed by poorer correlations between Bsp and coarse particulate matter measured during a fall sampling period. 相似文献