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121.
The influence of shade and clouds on soil water potential: The buffered behavior of hydraulic lift 总被引:3,自引:0,他引:3
In the sagebrush/bunchgrass steppe of the North American Great Basin soil water potential has been shown to exhibit diel fluctuations
with water potential increasing during the night as a result of water loss from roots in relatively dry soil layers. We hypothesized
that environmental conditions promoting low transpiration rates (shading, cloudiness) would cause a net increase in soil water
potential as a result of reduced soil water depletion during the day and continuing water efflux from roots during the night.
We examined the response of soil water potential to artificial shading in sagebrush/bunchgrass plantings and used a simple
model to predict how soil water potential should respond to reduced transpiration. Field measurements of soil water potential
indicated that shading reduced daytime soil water depletion, but that the magnitude of the soil water potential increase during
the night was related to the magnitude of the soil water potential decline during the preceding day. As a result, shading
had little net effect on soil water potential. This behavior was consistent with model results and appears to result from
the fact that soil water depletion during the day is largely responsible for creating the water potential gradients that drive
nocturnal recharge of the shallow soil layers. The overall effect of such behavior is to buffer the seasonal course of soil
water depletion in the rooting zone against day-to-day fluctuations in evapotranspiration. Despite the buffered behavior of
soil water potential change, reduced evapotranspiration during light summer rains, and resulting soil water redistribution
in the rooting zone, may enhance plant water status to a greater extent that would be expected on the basis of the rainfall
received. 相似文献
122.
Bt棉叶对棉铃虫抗虫性的时空变化及气象因素的影响 总被引:9,自引:4,他引:9
用叶片喂饲法,测定了转Bt基因棉不同叶位、不同生长时期的叶片对棉铃虫初孵幼虫抗虫性的时空变化,同时测定了大田和室内不同气象条件下生长的侧枝和苗期叶片对棉铃虫抗虫性的影响。结果表明:转Bt基因棉R19-137株系主茎第2~10叶的抗虫性最高,初孵幼虫处理5天后的平均死亡率为97.0%~100%,为害级别在1.0~1.1级;第11~16叶的抗虫性明显下降,平均死亡率为35.6%~67.6%,存活幼虫以2龄为主。7月下旬、8月下旬测定了不同部位侧枝叶片的抗虫性,平均死亡率分别为30.9%~44.9%和10.0%~30.0%,抗虫效果进一步下降。试验结果还表明,在室内外不同气候条件下生长的Bt棉叶片的抗虫性有显著差异。讨论了Bt棉抗虫性时空变化的可能原因与Bt棉推广中气候条件的重要性。 相似文献
123.
Patrick H. Wightman James A. Martin John C. Kilgo Emily Rushton Bret A. Collier Michael J. Chamberlain 《Ecology and evolution》2022,12(6)
Gobbling activity of Eastern wild turkeys (Meleagris gallopavo silvestris; hereafter, turkeys) has been widely studied, focusing on drivers of daily variation. Weather variables are widely believed to influence gobbling activity, but results across studies are contradictory and often equivocal, leading to uncertainty in the relative contribution of weather variables to daily fluctuations in gobbling activity. Previous works relied on road‐based auditory surveys to collect gobbling data, which limits data consistency, duration, and quantity due to logistical difficulties associated with human observers and restricted sampling frames. Development of new methods using autonomous recording units (ARUs) allows researchers to collect continuous data in more locations for longer periods of time, providing the opportunity to delve into factors influencing daily gobbling activity. We used ARUs from 1 March to 31 May to detail gobbling activity across multiple study sites in the southeastern United States during 2014–2018. We used state‐space modeling to investigate the effects of weather variables on daily gobbling activity. Our findings suggest rainfall, greater wind speeds, and greater temperatures negatively affected gobbling activity, whereas increasing barometric pressure positively affected gobbling activity. Therefore, when using daily gobbling activity to make inferences relative to gobbling chronology, reproductive phenology, and hunting season frameworks, stakeholders should recognize and consider the potential influences of extended periods of inclement weather. 相似文献
124.
Youbing Zhou Chris Newman Jin Chen Zongqiang Xie David W. Macdonald 《Global Change Biology》2013,19(9):2867-2877
Ongoing global climate change is predicted to increase the frequency and magnitude of extreme weather events, impacting population dynamics and community structure. There is, however, a critical lack of case studies considering how climatic perturbations affect biotic interactions. Here, we document how an obligate seed dispersal mutualism was disrupted by a temporally anomalous and meteorologically extreme interlude of unseasonably frigid weather, with accompanying snowstorms, in subtropical China, during January–February 2008. Based on the analysis of 5892 fecal samples (representing six mammalian seed dispersers), this event caused a substantial disruption to the relative seed dispersal function for the raisin tree Hovenia dulcis from prestorm 6.29 (2006) and 11.47 (2007), down to 0.35 during the storm (2008). Crucially, this was due to impacts on mammalian seed dispersers and not due to a paucity of fruit, where 4.63 fruit per branch were available in January 2008, vs. 3.73 in 2006 and 3.58 in 2007. An induced dietary shift occurred among omnivorous carnivores during this event, from the consumption fruit to small mammals and birds, reducing their role in seed dispersal substantially. Induced range shift extinguished the functionality of herbivorous mammals completely, however, seed dispersal function was compensated in part by three omnivorous carnivores during poststorm years, and thus while the mutualism remained intact it was enacted by a narrower assemblage of species, rendering the system more vulnerable to extrinsic perturbations. The storm's extended effects also had anthropogenic corollaries – migrating ungulates becoming exposed to heightened levels of illegal hunting – causing long‐term modification to the seed dispersal community and mutualism dynamics. Furthermore, degraded forests proved especially vulnerable to the storm's effects. Considering increasing climate variability and anthropogenic disturbance, the impacts of such massive, aberrant events warrant conservation concern, while affording unique insights into the stability of mutualisms and the processes that structure biodiversity and mediate ecosystem dynamics. 相似文献
125.
Bart Kranstauber Silke Bauer Judy Shamoun-Baranes 《Global Ecology and Biogeography》2023,32(11):1928-1936
Aim
Millions of birds take to the air for nocturnal migrations. Although it is widely recognized that migrants generally depart after sunset, nightly migration timing and their dependence on geographic features are hardly known at a continental scale, yet highly important for the mitigation of human-wildlife conflicts. Using weather radars, we investigate barrier and seasonal effects on the timing of nocturnal bird migration.Location
North western Europe: United Kingdom, Germany, Belgium, the Netherlands, France, Sweden and Finland.Time Period
2014–2020.Major Taxa Studied
Aves, nocturnal migrants, predominantly passerines.Methods
We use nocturnal bird migration distributions extracted from 55 weather radars. The variation between these temporal distributions is captured using a principal component analysis, barrier effects and seasonal differences are investigated with a general linear model.Results
Most variation in nightly migration timing can be explained by a univariate axis that distinguished a more evenly spread migration from a skewed migration. We found migration to be more evenly spread in spring and to have a clear peak early in the night in fall. Furthermore, migration is more peaked early in the night on locations close to or just upstream of major geographic barriers.Conclusions
Our study shows that migration fluxes tend to be more skewed during the night along coastlines and more uniform inland, far from water barriers. Regional and seasonal differences in nocturnal timing can provide vital information for adjusting the timing of wind park curtailment, lights-out initiatives or other conflicts between migratory birds and human activities. 相似文献126.
Chad T. Beranek Andrew J. Hamer Stephen V. Mahony Andrew Stauber Shelby A. Ryan John Gould Samantha Wallace Sarah Stock Oliver Kelly Thomas Parkin Rudolf Weigner Garry Daly Alex Callen Jodi J. L. Rowley Kaya Klop-Toker Michael Mahony 《Diversity & distributions》2023,29(6):785-800
Aim
Changes to the extent and severity of wildfires driven by anthropogenic climate change are predicted to have compounding negative consequences for ecological communities. While there is evidence that severe weather events like drought impact amphibian communities, the effects of wildfire on such communities are not well understood. The impact of wildfire on amphibian communities and species is likely to vary, owing to the diversity of their life-history traits. However, no previous research has identified commonalities among the amphibians at most risk from wildfire, limiting conservation initiatives in the aftermath of severe wildfire. We aimed to investigate the impacts of the unprecedented 2019–2020 black summer bushfires on Australian forest amphibian communities.Location
Eastern coast of New South Wales, Australia.Methods
We conducted visual encounter surveys and passive acoustic monitoring across 411 sites within two regions, one in northeast and one in southeast New South Wales. We used fire severity and extent mapping in two multispecies occupancy models to assess the impacts of fire on 35 forest amphibian species.Results
We demonstrate a negative influence of severe fire extent on metacommunity occupancy and species richness in the south with weaker effects in the north—reflective of the less severe fires that occurred in this region. Both threatened and common species were impacted by severe wildfire extent. Occupancy of burrowing species and rain forest specialists had mostly negative relationships with severe wildfire extent, while arboreal amphibians had neutral relationships.Main Conclusion
Metacommunity monitoring and adaptive conservation strategies are needed to account for common species after severe climatic events. Ecological, morphological and life-history variation drives the susceptibility of amphibians to wildfires. We document the first evidence of climate change-driven wildfires impacting temperate forest amphibian communities across a broad geographic area, which raises serious concern for the persistence of amphibians under an increasingly fire-prone climate. 相似文献127.
Interactions between the atmosphere and terrestrial ecosystems: influence on weather and climate 总被引:15,自引:0,他引:15
Roger A. Pielke . Sr RonI. Avissar † Michael Raupach ‡ A. Johannes Dolman § Xubin Zeng ¶ A. Scott Denning 《Global Change Biology》1998,4(5):461-475
This paper overviews the short-term (biophysical) and long-term (out to around 100 year timescales; biogeochemical and biogeographical) influences of the land surface on weather and climate. From our review of the literature, the evidence is convincing that terrestrial ecosystem dynamics on these timescales significantly influence atmospheric processes. In studies of past and possible future climate change, terrestrial ecosystem dynamics are as important as changes in atmospheric dynamics and composition, ocean circulation, ice sheet extent, and orbit perturbations. 相似文献
128.
Influence of environmental conditions and parasitoid quality on field performance of Trichogramma minutum 总被引:1,自引:0,他引:1
The effects of weather conditions and two parasitoid quality attributes, realized fecundity and host acceptance, were assessed on the field efficacy of mass-released Trichogramma minutum. Temperature was the most important single variable, explaining up to 75% of the variation in field parasitism. There were significant positive relationships between both the sum of the maximum temperatures and the number of degree-hours above a 15 °C threshold, accumulated in the three days following the release, and parasitism in the field. There was a significant negative relationship between the mean relative humidity and the odds of parasitism in the field. Quality parameters based on parasitoid biology were not effective for predicting field efficacy if poor weather conditions persisted after a release. If weather conditions were good (i.e. accumulated maximum temperatures above 62 °C, in the 3 days following the release), then parameters such as release rate and fecundity in the lab were useful predictors of field performance. There was no relationship between host acceptance measured in the lab and field parasitism. Given the importance of field temperatures for field performance, selection for cold tolerance of T. minutum would be desirable. 相似文献
129.
Grasshopper populations and weather: the effects of insolation on Chorthippus brunneus 总被引:1,自引:0,他引:1
MICHAEL BEGON 《Ecological Entomology》1983,8(4):361-370
ABSTRACT.
- 1 In nature, the internal body temperature of Chorthippus brunneus Thunberg is found to be raised substantially under the influence of direct insolation.
- 2 In the laboratory, similarly raised body temperatures, resulting from the radiant heat of a light bulb, lead to a 5.6-fold increase in the rate of development, and a similar or even higher increase in the rate of adult maturation. The rate of egg-production is even more greatly affected, being negligible in the absence of a radiant-heat source.
- 3 These physiological results provide an explanation for the frequently found correlation between grasshopper abundance and hot and/or dry weather.
- 4 The results are also discussed in terms of the problems they pose for the derivation of a physiological time-scale for basking insects, and the evolutionary forces and constraints that might give rise to them.
130.
Climate versus weather extremes: Temporal predictor resolution matters for future rather than current regional species distribution models 下载免费PDF全文
Stephan Feldmeier Lukas Schefczyk Axel Hochkirch Stefan Lötters Manfred A. Pfeifer Günther Heinemann Michael Veith 《Diversity & distributions》2018,24(8):1047-1060