红碱淖湖泊沉积记录的近五十年来的环境变化

对红碱淖湖泊短钻岩芯沉积物进行了粒度、碳酸盐以及有机质含量等环境代用指标分析,恢复了红碱淖近五十年以来的环境变化过程。依据红碱淖湖泊沉积记录,可以将红碱淖过去五十年的环境变化大致划分为2大阶段：第一阶段（A阶段,1957～1996年）,湖泊环境变化的影响因素以自然因素为主,经历了迅速扩张（1957～1969年）、基本稳定（1969～1990年）和渐趋萎缩（1990～1996年）三个亚阶段;第二阶段（B阶段,1996～2005年）,湖泊面积缩小,但指标中碳酸盐含量减少,有机质含量快速增加,指示湖泊沉积环境受人类活动影响强烈,碳酸盐保存条件发生改变,碳酸盐含量在这种情况下已不能指示湖泊环境变化。     

椰子间作可可下可可光合日变化与环境因子的关系

研究椰子间作可可下的可可光合速率(Pn)和环境因子日变化,探讨间作可可Pn与环境因子的关系,为优化可可栽培技术提供理论依据。结果表明,间作和单作可可Pn日变化均呈双峰曲线,有光合"午休"现象。环境因子与Pn的相关性均不显著(p0.05),间作和单作可可环境因子对Pn的直接作用均为TLRHPARTa,对间作可可Pn的影响是PAR、TL和Ta等相互作用的结果。光合有效辐射是影响间作可可Pn的主要环境因子。在可可的栽培管理中,应发挥主导环境因子的作用。     

人参展叶期净光合速率与环境因子日变化的关系研究

利用CI-340超轻型便携式光合测定系统,在人参展叶期对1、3、5年生人参的净光合速率与环境因子的日变化进行测定,并进行数据分析,目的是阐明人参叶片光合作用中净光合速率与主要的环境因子日变化之间的规律。结果表明：在展叶期各种环境因子的日变化过程中,各种环境因子相互协同作用,共同影响人参净光合速率水平。研究发现,各种环境因子都在适宜的范围内对人参光合作用有促进作用,而当环境因子变化超过一定范围后,都不同程度降低人参净光合速率,甚至出现净光合速率小于0的情况。     

Effects of experimental seaweed deposition on lizard and ant predation in an island food web

The effect of environmental change on ecosystems is mediated by species interactions. Environmental change may remove or add species and shift life-history events, altering which species interact at a given time. However, environmental change may also reconfigure multispecies interactions when both species composition and phenology remain intact. In a Caribbean island system, a major manifestation of environmental change is seaweed deposition, which has been linked to eutrophication, overfishing, and hurricanes. Here, we show in a whole-island field experiment that without seaweed two predators--lizards and ants--had a substantially greater-than-additive effect on herbivory. When seaweed was added to mimic deposition by hurricanes, no interactive predator effect occurred. Thus environmental change can substantially restructure food-web interactions, complicating efforts to predict anthropogenic changes in ecosystem processes.     

Modeling effects of environmental change on wolf population dynamics, trait evolution, and life history

Environmental change has been observed to generate simultaneous responses in population dynamics, life history, gene frequencies, and morphology in a number of species. But how common are such eco-evolutionary responses to environmental change likely to be? Are they inevitable, or do they require a specific type of change? Can we accurately predict eco-evolutionary responses? We address these questions using theory and data from the study of Yellowstone wolves. We show that environmental change is expected to generate eco-evolutionary change, that changes in the average environment will affect wolves to a greater extent than changes in how variable it is, and that accurate prediction of the consequences of environmental change will probably prove elusive.     

Global change and the ecology of cities

Urban areas are hot spots that drive environmental change at multiple scales. Material demands of production and human consumption alter land use and cover, biodiversity, and hydrosystems locally to regionally, and urban waste discharge affects local to global biogeochemical cycles and climate. For urbanites, however, global environmental changes are swamped by dramatic changes in the local environment. Urban ecology integrates natural and social sciences to study these radically altered local environments and their regional and global effects. Cities themselves present both the problems and solutions to sustainability challenges of an increasingly urbanized world.     

普那菊苣夏季光合速率日变化及其影响因子的研究

研究夏季普那菊苣叶片净光合速率日变化及其与影响因子的相互关系。利用CI-340便携式光合仪,测定了普那菊苣叶片净光合速率和环境因子(气温、光合有效辐射、空气相对湿度)、生理因子(蒸腾速率、胞间CO2浓度、气孔导度)的日变化;通过回归和通径分析,考察了影响因子对净光合速率日变化的影响。结果表明,在夏季自然晴天下,普那菊苣叶片的净光合速率呈双峰曲线,表现出"光午休"现象,保护性气孔导度降低,是高光强、高温下高光呼吸所致。     

我国农村居民消费结构变化及其环境影响分析

运用层次聚类方法和再扩展的扩展线性支出模型,划分了改革开放后我国农村居民的消费阶段,探讨了每一阶段农村经济政策的实施特点和这一阶段的农居环境问题,估算了近期农村居民消费方程,分析了不同收入等级农民的消费特点及其消费变化带来的农居环境影响,在此基础上,提出了优化农村居民的消费结构和提高农村居民生活环境质量的政策建议。     

Internal behavior in fish schools

Structural changes within fish schools correlate with declines in environmental oxygen. The changes may result from the responses of individual fish to the environmental consequences of group metabolism. Individual behaviors are adaptive to the school in that they tend to maintain stability between school members and their environment.     

红碱淖湖泊近50年来的环境变化分析——以湖泊沉积记录数据为依据

对红碱淖湖泊短钻岩芯沉积物进行了粒度、碳酸盐以及有机质含量等环境代用指标分析,恢复了红碱淖近50年以来的环境变化过程。依据红碱淖湖泊沉积记录,可以将红碱淖过去50年的环境变化大致划分为两大阶段：第一阶段（A阶段,1957～1996年）,湖泊环境变化的影响因素以自然因素为主,又经历了迅速扩张（A1阶段,1957～1969年）、基本稳定（A2阶段,1969～1990年）和渐趋萎缩（A3阶段,1990～1996年）3个亚阶段。A1阶段：这个时期粘粒和粉沙含量变化不明显,但粗颗粒含量减少、平均粒径变细,有机质含量在波动中上升,另外,这期间的TOC含量总体上略有上升。TOC含量的变化,除与碳酸盐含量的变化呈极好的负相关外,与平均粒径的变化也呈一定的负相关关系,平均粒径较细时TOC含量也较高。A2阶段：这一时期平均粒径值较稳定（1983～1984年除外）,各粒径含量虽然仍呈波动性变化,但没有明显的增减趋势;TOC与碳酸盐仍呈负相关关系,二者含量较A1阶段均略有增加。A3阶段：入湖颗粒中粉沙、粗颗粒含量均下降,以粘土为主,平均粒径减小,碳酸盐含量增加、有机质含量减少,说明气候偏干,流域生产力下降、入湖径流减少,水动力较弱,湖泊萎缩,面积减小。第二阶段（B阶段,1996～2005年）,湖泊面积缩小,但指标中碳酸盐含量减少,有机质含量快速增加,指示湖泊沉积环境受人类活动影响强烈,碳酸盐保存条件发生改变,碳酸盐含量在这种情况下已不能指示湖泊环境变化。     

干热河谷主要造林树种水分生理生态学特点

对８个造林树种的叶片自然含水量及蒸腾速率与环境因子的关系进行了分析。结果表明，蒸腾速率的日变化、含水量和蒸速速率的季节变化与大气温度和相对湿度密切相关，但各环境因子的影响各不相同。旱季，绢毛相思，马占相思，大叶相思，薄英相思和纹英相思是以减少蒸腾来抵御干旱，赤桉和肯氏相思以强大的根系来维持水分吸收能力，加大地上部分的蒸腾进行抗旱。     

土壤动物对土壤环境的生物指示作用

土壤动物对土壤环境生物指示作用的研究已成为国际土壤生态学领域的热点和前沿课题。土壤线虫对土壤环境(化肥、农药、除草剂和重金属)污染的生物指示研究,土壤原生动物对土壤中残留的有机污染物、农药和重金属的污染诊断的应用,蚯蚓物种多样性作为土壤环境污染的指示生物研究,土壤螨类种类组成和密度与土壤环境的变化的研究等越来越被国内外学者重视。笔者阐述了土壤动物对土壤环境变化生物指示作用的必然性和重要性。     

Integration of plant responses to environmentally activated phytohormonal signals

Plants live in fixed locations and survive adversity by integrating growth responses to diverse environmental signals. Here, we show that the nuclear-localized growth-repressing DELLA proteins of Arabidopsis integrate responses to independent hormonal and environmental signals of adverse conditions. The growth restraint conferred by DELLA proteins is beneficial and promotes survival. We propose that DELLAs permit flexible and appropriate modulation of plant growth in response to changes in natural environments.     

CikA, a bacteriophytochrome that resets the cyanobacterial circadian clock

The circadian oscillator of the cyanobacterium Synechococcus elongatus, like those in eukaryotes, is entrained by environmental cues. Inactivation of the gene cikA (circadian input kinase) shortens the circadian period of gene expression rhythms in S. elongatus by approximately 2 hours, changes the phasing of a subset of rhythms, and nearly abolishes resetting of phase by a pulse of darkness. The CikA protein sequence reveals that it is a divergent bacteriophytochrome with characteristic histidine protein kinase motifs and a cryptic response regulator motif. CikA is likely a key component of a pathway that provides environmental input to the circadian oscillator in S. elongatus.     

Telecoupled land-use changes in distant countries

International food trade has become a key driving force of agricultural land-use changes in trading countries,which has influenced food production and the global environment. Researchers have studied agricultural land-use changes and related environmental issues across multi-trading countries together,but most studies rely on statistic data without spatial attributes. However,agricultural land-use changes are spatially heterogeneous. Uncovering spatial attributes can reveal more critical information that is of scientific significance and has policy implications for enhancing food security and protecting the environment. Based on an integrated framework of telecoupling(socioeconomic and environmental interactions over distances),we studied spatial attributes of soybean land changes within and among trading countries at the same time. Three distant countries- Brazil,China,and the United States- constitute an excellent example of telecoupled systems through the process of soybean trade. Our results presented the spatial distribution of soybean land changes- highlighting the hotspots of soybean gain and soybean loss,and indicated these changes were spatially clustered,different across multi-spatial scales,and varied among the trading countries. Assisted by the results,global challenges like food security and biodiversity loss within and among trading countries can be targeted and managed efficiently. Our work provides simultaneously spatial information for understanding agricultural land-use changes caused by international food trade globally,highlights the needs of coordination among trading countries,and promotes global sustainability.     

Forecasting agriculturally driven global environmental change

During the next 50 years, which is likely to be the final period of rapid agricultural expansion, demand for food by a wealthier and 50% larger global population will be a major driver of global environmental change. Should past dependences of the global environmental impacts of agriculture on human population and consumption continue, 10(9) hectares of natural ecosystems would be converted to agriculture by 2050. This would be accompanied by 2.4- to 2.7-fold increases in nitrogen- and phosphorus-driven eutrophication of terrestrial, freshwater, and near-shore marine ecosystems, and comparable increases in pesticide use. This eutrophication and habitat destruction would cause unprecedented ecosystem simplification, loss of ecosystem services, and species extinctions. Significant scientific advances and regulatory, technological, and policy changes are needed to control the environmental impacts of agricultural expansion.     

Cardiovascular actions of cadmium at environmental exposure levels

A low intake of dietary cadmium induces specific dose-dependent functional and biochemical changes in the cardiovascular tissues of rats. Maximum changes occur when the cadmium intake is 10 to 20 micrograms per kilogram of body weight per day. The changes reflect the accumulation of "critical" concentrations of cadmium in the cardiovascular tissues. The biologic activity of cadmium is demonstrated for intakes that approach those of the average American adult exposed to the usual environmental concentrations of the element but not to industrial concentrations. The sensitivity of the cardiovascular system to low doses of cadmium could not be anticipated by extrapolation from data on exposure to high concentrations of cadmium. The data support the hypothesis that ingested or inhaled environmental cadmium may contribute to essential hypertension in humans.     

黄芪多糖对小叶杨逆境胁迫下保护酶系统的影响

[目的]探究黄芪多糖对小叶杨对抗逆境胁迫能力的影响.[方法]研究小叶杨在低温和干旱逆境条件下体内过氧化氢酶（CAT）、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性的变化.[结果]在短时间内,经过一定浓度黄芪多糖处理的小叶杨保护酶活性较高,而一定时间后黄芪多糖处理组的小叶杨保护酶的活性较低.[结论]黄芪多糖可能提高了小叶杨抗逆境胁迫的能力.     

Phenotypic diversity, population growth, and information in fluctuating environments

Organisms in fluctuating environments must constantly adapt their behavior to survive. In clonal populations, this may be achieved through sensing followed by response or through the generation of diversity by stochastic phenotype switching. Here we show that stochastic switching can be favored over sensing when the environment changes infrequently. The optimal switching rates then mimic the statistics of environmental changes. We derive a relation between the long-term growth rate of the organism and the information available about its fluctuating environment.     

城市景观格局演变的生态环境效应研究进展

快速城市化过程剧烈影响着下垫面变化,直接带来了交通拥挤、资源短缺、环境污染、生态恶化等诸多问题,所有这些问题的出现均与景观格局演变密切相关,研究城市景观格局演变及其生态环境效应正在成为全社会关注的热点.系统总结了城市化过程对景观格局演变的影响,分析了城市景观格局演变的热环境效应、水环境效应、生态服务效应,以及城市生态用地与生态安全格局设计等方面的研究进展.指出了目前城市景观演变与生态环境效应研究中存在的问题与不足:(1)现有研究侧重于景观格局演变的量化分析和景观格局指数的计算,较少关注景观格局演变对生态环境及其区域生态安全的影响;(2)城市景观格局演变与热岛效应研究多局限于两者数理统计关系的分析,对于城市热环境形成的机理缺乏深入研究;(3)城市景观格局演变与大气环境效应方面更多研究关注绿地及其空间布局在吸收和降解大气污染物、固体颗粒物方面的作用,对城市景观格局演变的大气环境综合效应以及大气灰霾效应影响机理重视不够;(4)如何通过合理设置生态用地,有效提高城市生态服务功能和保障城市生态安全,目前仍缺乏深入而又系统的研究.下一步的研究中,需要综合多尺度的景观信息来揭示城市景观的演变机理和环境效应,构建基于城市空间扩展和生态服务效应评价的城市生态空间优化决策模型,探讨城市生态空间优化模式与安全格局.