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11.
Citizen science has been gaining momentum in the United States and Europe, where citizens are literate and often interested in science. However, in developing countries, which have a dire need for environmental data, such programs are slow to emerge, despite the large and untapped human resources in close proximity to areas of high biodiversity and poorly known floras and faunas. Thus, we propose that the parataxonomist and paraecologist approach, which originates from citizen‐based science, is well suited to rural areas in developing countries. Being a paraecologist or a parataxonomist is a vocation and entails full‐time employment underpinned by extensive training, whereas citizen science involves the temporary engagement of volunteers. Both approaches have their merits depending on the context and objectives of the research. We examined 4 ongoing paraecologist or parataxonomist programs in Costa Rica, India, Papua New Guinea, and southern Africa and compared their origins, long‐term objectives, implementation strategies, activities, key challenges, achievements, and implications for resident communities. The programs supported ongoing research on biodiversity assessment, monitoring, and management, and participants engaged in non‐academic capacity development in these fields. The programs in Southern Africa related to specific projects, whereas the programs in Costa Rica, India, and Papua New Guinea were designed for the long term, provided sufficient funding was available. The main focus of the paraecologists’ and parataxonomists’ activities ranged from collection and processing of specimens (Costa Rica and Papua New Guinea) or of socioeconomic and natural science data (India and Southern Africa) to communication between scientists and residents (India and Southern Africa). As members of both the local land user and research communities, paraecologists and parataxonomists can greatly improve the flow of biodiversity information to all users, from local stakeholders to international academia.  相似文献   
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Prediction of phosphorus (P) availability from soil-applied composts and manure is important for agronomic and environmental reasons. This study utilized chemical properties of eight composted and two non-composted beef cattle (Bos taurus) manures to predict cumulative phosphorus uptake (CPU) during a 363-d controlled environment chamber bioassay. Ten growth cycles of canola (Brassica napus L.) were raised in pots containing 2 kg of a Dark Brown Chernozemic clay loam soil (fine-loamy, mixed, Typic Haploboroll) mixed with 0.04 kg of the amendments. Inorganic P fertilizer (KH2PO4) and an unamended control were included for comparison. All treatments received a nutrient solution containing an adequate supply of all essential nutrients, except P, which was supplied by the amendments. Cumulative P uptake was similar for composted (74 mg kg-1 soil) and non-composted manures (60 mg kg-1 soil) and for the latter and the fertilizer (40 mg kg-1 soil). However, the CPU was significantly higher for organic amendments than the control (24 mg kg-1 soil) and for composted manure than the fertilizer. Apparent phosphorus recovery (APR) from composted manure (24%) was significantly lower than that from non-composted manure (33%), but there was no significant difference in APR between the organic amendments and the fertilizer (27%). Partial least squares (PLS) regression indicated that only two parameters [total water-extractable phosphorus (TPH2O) and total phosphorus (TP) concentration of amendments] were adequate to model amendment-derived cumulative phosphorus uptake (ACPU), explaining 81% of the variation in ACPU. These results suggest that P availability from soil-applied composted and non-composted manures can be adequately predicted from a few simple amendment chemical measurements. Accurate prediction of P availability and plant P recovery may help tailor manure and compost applications to plant needs and minimize the buildup of bioavailable P, which can contribute to eutrophication of sensitive aquatic systems.  相似文献   
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Remote cameras are an increasingly important tool for ecological research. While remote camera traps collect field data with minimal human attention, the images they collect require post-processing and characterization before it can be ecologically and statistically analyzed, requiring the input of substantial time and money from researchers. The need for post-processing is due, in part, to a high incidence of non-target images. We developed a stand-alone semi-automated computer program to aid in image processing, categorization, and data reduction by employing background subtraction and histogram rules. Unlike previous work that uses video as input, our program uses still camera trap images. The program was developed for an ungulate fence crossing project and tested against an image dataset which had been previously processed by a human operator. Our program placed images into categories representing the confidence of a particular sequence of images containing a fence crossing event. This resulted in a reduction of 54.8% of images that required further human operator characterization while retaining 72.6% of the known fence crossing events. This program can provide researchers using remote camera data the ability to reduce the time and cost required for image post-processing and characterization. Further, we discuss how this procedure might be generalized to situations not specifically related to animal use of linear features.  相似文献   
16.
Lenz M  Janzen N  Lens PN 《Chemosphere》2008,73(3):383-388
Inhibitory effects of selenite and selenate towards hydrogenotrophic and acetoclastic methanogenesis were evaluated in anaerobic toxicity assays. The 50% inhibitory concentration (IC(50)) of both selenium oxyanions was below 6.1x10(-5)M in hydrogenotrophic assays, whereas acetoclastic methanogens were less inhibited: IC(50)=8.3x10(-5)M and 5.5x10(-4)M for selenite and selenate, respectively. Selenite completely inhibits methanogenesis from both substrates tested at concentrations 10(-3)M selenite, while only marginal methanogenic activities occur at equimolar concentrations of selenate. Selenite becomes irreversibly inhibitory upon a single exposure, whereas selenate inhibits methanogens upon repeated exposure. Consequently, methane recovery can be seriously hampered or even impossible during anaerobic treatment of highly selenium contaminated waste streams.  相似文献   
17.
Schwanz LE  Spencer RJ  Bowden RM  Janzen FJ 《Ecology》2010,91(10):3016-3026
Conditions experienced early in life can influence phenotypes in ecologically important ways, as exemplified by organisms with environmental sex determination. For organisms with temperature-dependent sex determination (TSD), variation in nest temperatures induces phenotypic variation that could impact population growth rates. In environments that vary over space and time, how does this variation influence key demographic parameters (cohort sex ratio and hatchling recruitment) in early life stages of populations exhibiting TSD? We leverage a 17-year data set on a population of painted turtles, Chrysemys picta, to investigate how spatial variation in nest vegetation cover and temporal variation in climate influence early life-history demography. We found that spatial variation in nest cover strongly influenced nest temperature and sex ratio, but was not correlated with clutch size, nest predation, total nest failure, or hatching success. Temporal variation in climate influenced percentage of total nest failure and cohort sex ratio, but not depredation rate, mean clutch size, or mean hatching success. Total hatchling recruitment in a year was influenced primarily by temporal variation in climate-independent factors, number of nests constructed, and depredation rate. Recruitment of female hatchlings was determined by stochastic variation in nest depredation and annual climate and also by the total nest production. Overall population demography depends more strongly on annual variation in climate and predation than it does on the intricacies of nest-specific biology. Finally, we demonstrate that recruitment of female hatchlings translates into recruitment of breeding females into the population, thus linking climate (and other) effects on early life stages to adult demographics.  相似文献   
18.
Livestock manure in feedlots releases ammonia (NH3), which can be sorbed by nearby soil and plants. Ammonia sorption by soil and its effects on soil and perennial grass N contents downwind from two large cattle feedlots in Alberta, Canada were investigated from June to October 2002. Atmospheric NH3 sorption was measured weekly by exposing air-dried soil at sampling points downwind along 1700-m transects. The amount of NH3 sorbed by soil was 2.60 to 3.16 kg N ha(-1) wk(-1) near the source, declining to about 0.25 kg N ha(-1) wk(-1) 1700 m downwind, reflecting diminishing atmospheric NH3 concentrations. Ammonia sorption at a control site away from NH3 sources was much lower: 0.085 kg N ha(-1) wk(-1). Based on these rates, about 19% of emitted NH3 is sorbed by soil within 1700 m downwind of feedlots. Field soil and grass samples from the transect lines were analyzed for total N (TN) and KCl-extractable N content (soil only). Nitrate N content in field soil followed a trend similar to that of atmospheric NH3 sorption. Soil TN contents, because of high background levels, showed no clear pattern. The TN content of grass, downwind of the newer feedlot, followed a pattern similar to that of NH3 sorption; downwind of the older feedlot, grass TN was correlated to soil TN. Our results suggest that atmospheric NH3 from livestock operations can contribute N to local soil and vegetation, and may need to be considered when determining fertilizer rates and assessing environmental impact.  相似文献   
19.
Janzen N  Dopp E  Hesse J  Richards J  Türk J  Bester K 《Chemosphere》2011,85(9):1481-1486
The reaction of the fragrance compounds 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (HHCB), 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone (AHTN), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene/MX), 1-(4-tert-butyl-2,6-dimethyl-3,5-dinitrophenyl)ethanone (musk ketone/MK), and 1-(2,3,8,8-tetramethyl-1,3,4,5,6,7-hexahydronaphthalen-2-yl)ethanone (OTNE) with ozone in tap water as well as waste water treatment plant (WWTP) effluents is described. Several transformation products are characterized by means of gas chromatography coupled to mass spectrometry. One transformation product (HHCB-Lactone) was confirmed by means of a true standard. Musk xylene and musk ketone do not react with ozone under the conditions used in this study. AHTN and HHCB reacted slowly to a multitude of transformation products, while OTNE reacted quickly to several stable transformation products. The reaction constants and half lives are used to predict removal efficiencies for full scale reactors.  相似文献   
20.
Soil carbon dynamics and potential carbon sequestration by rangelands   总被引:14,自引:0,他引:14  
The USA has about 336 Mha of grazing lands of which rangelands account for 48%. Changes in rangeland soil C can occur in response to a wide range of management and environmental factors. Grazing, fire, and fertilization have been shown to affect soil C storage in rangelands, as has converting marginal croplands into grasslands. Carbon losses due to soil erosion can influence soil C storage on rangelands both by reducing soil productivity in source areas and potentially increasing it in depositional areas, and by redistributing the C to areas where soil organic matter mineralization rates are different. Proper grazing management has been estimated to increase soil C storage on US rangelands from 0.1 to 0.3 Mg C ha(-1)year(-1) and new grasslands have been shown to store as much as 0.6 Mg C ha(-1)year(-1). Grazing lands are estimated to contain 10-30% of the world's soil organic carbon. Given the size of the C pool in grazing lands we need to better understand the current and potential effects of management on soil C storage.  相似文献   
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