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951.
Context
Many studies dichotomize habitat selection into “local” or “landscape” effects, with little explanation regarding what each represents. Ambiguous use of these terms across studies may confound observations of selection operating across different spatiotemporal resolutions and impede synthesis of scale-dependent habitat selection.Objective
To examine the consistency of use of the terms “local” and “landscape” level habitat selection and evaluate potential implications for conservation science.Methods
We reviewed 136 multi-level studies observing local and/or landscape effects. From each study, we identified which of Johnson’s (Ecology 61:65–71, 1980) selection orders was observed at the local and landscape scale. We assessed consistency in the selection order observed at each scale.Results
At the local scale, 54% of studies observed 3rd order selection and 38% of studies observed 4th order selection. At the landscape scale, 64% of studies observed 2nd order selection, while only 8% of studies observed 1st order selection. Overlap also occurred; 2nd order selection was observed at the local scale in 8% of studies, while 3rd and 4th order selection was observed at the landscape scale in 24 and 3% of studies, respectively.Conclusions
Selection orders observed at local and landscape scales are inconsistent across studies, making comparisons and synthesis difficult. This inconsistency makes the terms “local” and “landscape” meaningless, and may lead to misidentification of limiting factor(s) most important for conservation efforts. Dichotomous terms should no longer be used in reference to levels of selection, but in reference to specific explanatory variables whose characteristic scale(s) best fit the appropriate definition.952.
Olga M. Grant Michael J. Davies Helen Longbottom Christopher J. Atkinson 《Irrigation Science》2009,27(2):139-153
Water use and plant growth and quality were compared across different nursery stock beds, different methods of applying irrigation,
and different methods of scheduling irrigation. With overhead irrigation, scheduling of irrigation according to plant demand,
along with an irrigation system designed to maximise irrigation uniformity, resulted in substantial water savings, without
reducing plant quality. This was the case in both wet and dry years. In the dry year, plant quality was particularly good
when grown on a sub-irrigated sand bed; this system also used less water than any of the overhead irrigation systems. Two
different systems were effective in scheduling overhead irrigation, one based on the volumetric moisture in the growing substrate,
and the other based on plant evapotranspiration. The latter was determined with a small sensor with wet and dry artificial
“leaves”, the output of which correlated with that obtained following the Penman–Monteith method based on a full set of meteorological
data. 相似文献
953.
954.
Gravel pit wetland habitats are a new and rapidly expanding feature of the contemporary environment in Britain. This paper investigates and emphasises their value as potential conservation areas for breeding bird communities. Most gravel pits are characterised by close proximity to man in an urban-agricultural environment, but contain a variety of aquatic, marshland and terrestrial habitats. Their breeding bird communities contain a wide variety of species, often at high breeding densities. As natural wetlands come under increasing pressure, it is suggested that these new wetlands are important for the future conservation of marshland and aquatic species, and may also act as reservoirs of diversity and abundance in a rapidly changing environment. Conservation of some gravel pits should be based on their overall value as conservation, education and recreation areas near urban centres, and others could relieve the increasing public pressure on natural wetlands. Present trends in the utilisation of gravel pits for recreation are discussed and ultimately it is hoped to show how conservation and recreation may or may not co-exist in the new wetlands of the future. 相似文献
955.
Recruitment ecology of pelagic‐broadcast spawning minnows: paradigms from the ocean advance science and conservation of an imperilled freshwater fauna 下载免费PDF全文
Pelagic‐broadcast spawning is a dominant mode of fish reproduction in the oceans and is associated with Fundamental Triad (i.e. nutrient enrichment, nutrient concentration, propagule retention) and Loophole (i.e. disruption of larval competition and predation) processes that are mediated by water currents. Pelagic‐broadcast spawning is uncommon in freshwater, but is employed by an evolutionarily convergent spawning guild in rivers on the Great Plains, North America. We reviewed ecological studies of pelagic‐broadcast spawning minnows to evaluate whether Fundamental Triad and Loophole concepts explain the adaptive significance of this behaviour. Pelagic‐broadcast spawning minnows exhibit spawning periodicity dependent on floods. Nutrient enrichment, nutrient concentration and propagule retention are enhanced during flood recession. Retention is also enhanced by high fecundity and rapid development of pelagic‐broadcast propagules. Predation and competition threats are relatively low in temporary, patchily distributed nurseries present during flood recession. Extended spawning periods and diffusive spread of juveniles and adults ensure annual recruitment despite the unpredictable and often harsh conditions in rivers on the plains. Over the last century, pelagic‐broadcast spawners have suffered declines due to dewatering, flood control and sediment deprivation that disrupt natural Fundamental Triad and Loophole processes. We propose that restoration of conditions necessary for Fundamental Triad and Loophole processes to operate will be most successful at stopping decline and extinction of pelagic‐broadcast spawning minnows of the Great Plains. 相似文献
956.
Bologna was processed from ground turkey breast meats containing one of four antioxidant treatments (none, rosemary extract, sodium erythorbate, and sodium nitrite). After it was cooked, the bologna was sliced, sealed in gas impermeable bags, exposed to 0, 1.5, and 3.0 kGy gamma-radiation, and then stored at 5 degrees C for up to 8 weeks. Thiobarbuturic acid reactive substances (TBARS), color, and volatile sulfur compounds were measured every 2 weeks during storage. Irradiation had no consistent effect on TBARS values. The rosemary extract and sodium nitrite inhibited, while erythorbate increased, TBARS values, independent of radiation dose or storage time. Irradiation promoted redness and reduced yellowness of the control (no antioxidant) bologna at weeks 0 and 2. The use of nitrite and rosemary extract inhibited the changes in color due to irradiation. Several volatile sulfur compounds (hydrogen sulfide, methanethiol, methyl sulfide, and dimethyl disulfide), measured using a pulsed flame photometric detector, increased with radiation dose. However, none of the antioxidants had any substantial effect on volatile sulfur compounds induced by irradiation. Our results suggest that antioxidants did not consistently affect irradiation-induced volatile sulfur compounds of turkey bologna although they did significantly impact color and lipid oxidation. 相似文献
957.
Ester variability in apple varieties as determined by solid-phase microextraction and gas chromatography-mass spectrometry 总被引:2,自引:0,他引:2
Solid-phase microextraction (SPME) with a polydimethylsiloxane fiber coupled with gas chromatography-mass spectrometry (GC-MS) was applied to the study of variability in volatiles released by 13 apple varieties. The relative amounts of 40 esters and alpha-farnesene were determined. Principal component analyses of these results clustered the apples into three groups according to skin color: red, green, and red-green. Total ester contents were highest with the red cluster apples, and the green cluster apples had the highest alpha-farnesene levels. This technology was also applied to the monitoring of changes in volatiles for apples removed from controlled-atmosphere storage with subsequent storage at 4 degrees C and room temperature. Total ester contents increased 25-fold, with the greater increases coming at room temperature, whereas alpha-farnesene levels increased only 5-fold. For apples stored at room temperature, after 11 days, the amount of increase was inversely proportional to the size of the ester: levels of smallest esters (molecular weight 116) increased 12.5-fold, and the largest esters (molecular weight 228) increased approximately 1.3-fold. 相似文献
958.
Recent reports suggest that most of the world's commercial fisheries could collapse within decades. Although poor fisheries governance is often implicated, evaluation of solutions remains rare. Bioeconomic theory and case studies suggest that rights-based catch shares can provide individual incentives for sustainable harvest that is less prone to collapse. To test whether catch-share fishery reforms achieve these hypothetical benefits, we have compiled a global database of fisheries institutions and catch statistics in 11,135 fisheries from 1950 to 2003. Implementation of catch shares halts, and even reverses, the global trend toward widespread collapse. Institutional change has the potential for greatly altering the future of global fisheries. 相似文献
959.
Zuhair Masri Jerry Wilhm Christopher C. Underwood Nicholas T. Bancroft Jay Eccleton 《Communications in Soil Science and Plant Analysis》2019,50(7):795-810
A proprietary Flavonol Polymer Technology (FPT), designed by AgroLiquid, is an agent for encapsulating different chemistries on the polymer by impregnation to provide extended release of nutrients and optimize yield. Based on FPT, FPT-Product (Pro-Germinator®) a 9-24-3 (% N, % P2O5, and % K2O w/w) manufactured to slow the phosphorus release process in soil and extends its usability by the plant. Phosphorus release was evaluated using micro-lysimeters installed in soil and used as a tool for the collection of the plant-usable phosphorus dissolved in the soil solution. A rate of 22 kg of P2O5/hectare of liquid formulations was banded in-furrow with four phosphorus liquid fertilizer treatments: (1) orthophosphate (9-18-9), (2) ammonium polyphosphate (10-34-0), (3) FPT-Product (9-24-3), and (4) a control. In-field measurements were collected at 20–60 days after the application for two successive years (2015 and 2016). In both years, averages of measured dissolved phosphorus in the soil solution and exchangeable soil phosphorus at 10-cm soil depth, 20–60 days after planting reported higher values in the FPT-Product treatments while lower values were measured in the other treatments. The results proved that the FPT extended the release mechanism for phosphorus in the FPT-Product at 10 cm depth in the soil, and rendered phosphorus in both the soil and the solution to be used by plants for an extended period after corn planting. 相似文献
960.
用CFD方法模拟日光温室温度环境初探 总被引:23,自引:12,他引:23
日光温室温度环境为一动态变化过程,该文建立了求解晴天室内温度环境的计算模型。将室外的水平面太阳辐照度、天空辐射温度、室外空气相对湿度、空气温度、风速及室内1.0m深土壤温度作为边界条件,采用计算流体动力学技术(CFD)中的非稳态方法求解控制方程,模拟了晴天室内温度随外界气候条件的变化,结果显示模拟得到的室内空气温度及土壤温度变化规律与实测值变化规律相同,盖帘后室内空气温度及土壤0.2 m深土层的温度模拟值与实测值相差约在1℃以内;探讨了边界条件中冷风渗透、土壤表面太阳能转换显热份额及1.0 m深土壤温度的取值变化对室内温度的影响。日光温室内温度动态变化模拟模型的建立对优化温室设计参数和预测不同天气情况下室内的温度环境变化具有参考意义。 相似文献