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111.
Salinity and geomorphology drive long‐term changes to local and regional fish assemblage attributes in the lower Pecos River,Texas 下载免费PDF全文
River systems throughout arid regions worldwide have been heavily impacted by human activities, resulting in long‐term ecological consequences. The lower Pecos River in the Trans‐Pecos region of Texas is no exception, having undergone anthropogenic changes that include decreased flow, elevated salinity, species loss and species invasion. We compared historical and contemporary fish assemblage attributes from the Pecos River at local (site‐specific) and regional (Trans‐Pecos region) scales across a 24‐year time period. Fish assemblage data were collected in October 1987 and 2011, by seining at 15 sites spanning 430 km of the river in Texas. Additionally, we examined contemporary environmental conditions to determine species–environment relationships. We found that fish assemblages were significantly different between time periods, likely due to increased salinisation in the upper half of the study region. Decreased species richness, species replacement and increases in euryhaline species were documented in the upstream sites. Freshwater springs lower the salinity and maintain flows in the downstream reach, allowing for maintenance of the native fish fauna. Careful management of regional aquifers, irrigation practices and petroleum waste water will be necessary for protecting biodiversity and environmental flows in the lower Pecos River. 相似文献
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欧亚温带草原东缘生态样带研究探讨 总被引:1,自引:0,他引:1
为揭示全球变化与欧亚温带草原东缘生态系统的关系,提出沿着从中国长城至俄罗斯贝加尔湖设置一条经向样带,主要表征欧亚大陆东缘经向热量梯度,反映受大陆性气候控制下的草原地带的生态系列.沿样带开展生物地球化学过程、能量交换、植被结构动态、气候—植被、放牧—草地—牧草驯化、土地利用格局与管理、模型模拟等研究工作,对于加深气候变化和人为影响对草原生态系统的发生、发展、利用及演变规律的影响的认识,增强对气候变化的减缓和适应能力,具有非常重要的意义. 相似文献
114.
Studies of biological responses in the terrestrial environment to rapid changes in climate have mostly been concerned with aboveground biota, whereas less is known of belowground organisms. The present study focuses on mites and springtails of heathland ecosystems and how the microarthropod community has responded to simulated climate change in a long-term field experiment. Increased temperature and repeated drought was applied for 13 years to field plots located in Wales, The Netherlands and Denmark representing sites of contrasting climatic conditions with respect to precipitation and temperature. This approach provided an opportunity to study biological responses on a local (within sites) and regional scale. Warming treatments increasing night time temperature (0.3–1 °C higher than ambient at 5 cm soil depth) had no detectable effects on the microarthropod communities. Increased intensity and frequency of drought had only weak persistent effects on springtail species composition, but practically no effect on major mite groups (Oribatida, Prostigmata or Mesostigmata) suggesting that ecosystem functions of microarthropods may only be transiently impacted by repeated spring or summer drought. 相似文献
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通过问卷调查和SPSS软件,分析和探讨了农民气候适应性行为的现状及影响因素,并在此基础上思考探讨应对之策,即建立和健全农业科技服务体系,加强对农民气候认知和适应能力的教育培训,推进农民之间气候适应性行为的合作,加强对农民气候适应性行为的指导。 相似文献
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A possible mechanism of mineral responses to elevated atmospheric CO2 in rice grains 总被引:1,自引:0,他引:1
Increasing attentions have been paid to mineral concentration decrease in milled rice grains caused by CO2 enrichment, but the mechanisms still remain unclear. Therefore, mineral(Ca, Mg, Fe, Zn and Mn) translocation in plant-soil system with a FACE(Free-air CO2 enrichment) experiment were investigated in Eastern China after 4-yr operation. Results mainly showed that:(1) elevated CO2 significantly increased the biomass of stem and panicle by 21.9 and 24.0%, respectively, but did not affect the leaf biomass.(2) Elevated CO2 significantly increased the contents of Ca, Mg, Fe, Zn, and Mn in panicle by 61.2, 28.9, 87.0, 36.7, and 66.0%, respectively, and in stem by 13.2, 21.3, 47.2, 91.8, and 25.2%, respectively, but did not affect them in leaf.(3) Elevated CO2 had positive effects on the weight ratio of mineral/biomass in stem and panicle. Our results suggest that elevated CO2 can favor the translocation of Ca, Mg, Fe, Zn, and Mn from soil to stem and panicle. The CO2-led mineral decline in milled rice grains may mainly attribute to the CO2-led unbalanced stimulations on the translocations of minerals and carbohydrates from vegetative parts(e.g., leaf, stem, branch and husk) to the grains. 相似文献
119.
Effects of recent climate change have already been detected in many species, and, in particular, in insects. The present paper reviews the key impacts of global warming on insect development and dispersal. The effects of climate change appear to be much more complex than a simple linear response to an average increase in temperature. They can differ between seasons and bioclimatic regions. Earlier flight periods, enhanced winter survival and acceleration of development rates are the major insect responses. Differential response of insects and hosts to warming up might also lead to disruption of their phenological synchrony, but adaptive genetic processes are likely to quickly restore this synchrony. In a number of cases, warming results in removing or relocating the barriers that limit present species' ranges. It is also likely to facilitate the establishment and spread of invasive alien species. Finally, knowledge gaps are identified and future research interests are suggested. 相似文献
120.
绿洲是干旱区人民赖以自下而上的一片沃野。由于人类的强度作用,绿洲向复杂方向演变发展。本文以高台绿洲为例,以地下水位为指标确定了绿洲边界范围,进而研究了绿洲从1958年至1985年边界的变化,并分析高台绿洲农田和草地生态系统功能,指出草地生态系统的恶化是绿洲边界变化的重要原因,应当加强对草地的投入与管理。 相似文献