检索结果-南通市图书馆

Past climate and vegetation in Southeast Bulgaria——a study based on the late Miocene pollen record from the Tundzha Basin

在线全文

学校读者我要写书评

暂无评论

Journal of Palaeogeography 2019年第1期8卷 43-67页

作者： Dimiter Ivanov Maria Lazarova institute of Biodiversity and ecosystem research Bulgarian Academy of Sciences

The results of palynological studies on the late Miocene freshwater deposits of the Tundzha Basin(Southeast Bulgaria, SE Europe) are presented. The basin is relatively well known in terms of geology and *** age of sediments in the Tundzha Basin ranges between the late Miocene to the Pliocene, based on mammal and diatom fossils. We carried out a palynological analysis of clayey sediments interlayered with coal beds from four cores and from one outcrop, aiming to obtain information about the composition and the structure of fossil vegetation. The ratios between the main floristic elements and the composition of the fossil flora are analysed and discussed from a palaeoecological point of view. Several main vegetation palaeocommunities were recorded:swamp forests, mixed mesophytic, communities of aquatic plants, and herbaceous palaeocoenoses. The changes in vegetation and in plant diversity are identified. The palaeoclimate analysis indicates a warm temperature climate with high rainfall and mild winter temperatures, without seasonal drier conditions. The early Pontian climate was about 3–4 ℃ warmer than today, with rainfalls per year at least 300 mm higher than today. The results of palaeoecological analysis of the flora and of the quantitative palaeoclimate data show that the climate in the Southeast Bulgaria indicates a climate change towards slight cooling and some drying. This event is consistent with the period of accumulation of the upper, undivided part of the Elhovo Formation.

关键词： Palynology Palaeobotany Coexistence approach Neogene Tundzha Basin Bulgaria

Gut microbiota-astrocyte axis: new insights into age-related cognitive decline

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration research 2025年第4期20卷 990-1008页

作者： Lan Zhang Jingge Wei Xilei Liu Dai Li Xiaoqi Pang Fanglian Chen Hailong Cao Ping Lei Haihe Laboratory of Cell ecosystem Department of GeriatricsTianjin Medical University General HospitalTianjinChina Tianjin Geriatrics institute Tianjin Medical University General HospitalTianjinChina Department of Gastroenterology and Hepatology Tianjin Medical University General HospitalNational Key Clinical SpecialtyTianjin Institute of Digestive DiseasesTianjin Key Laboratory of Digestive DiseasesTianjinChina Department of Urology Tianjin Medical University General HospitalTianjinChina Tianjin Neurological Institution Tianjin Medical University General HospitalTianjinChina

With the rapidly aging human population,age-related cognitive decline and dementia are becoming increasingly prevalent *** is considered the main risk factor for cognitive decline and acts through alterations in the composition of the gut microbiota,microbial metabolites,and the functions of *** microbiota–gut–brain axis has been the focus of multiple studies and is closely associated with cognitive *** article provides a comprehensive review of the specific changes that occur in the composition of the gut microbiota and microbial metabolites in older individuals and discusses how the aging of astrocytes and reactive astrocytosis are closely related to age-related cognitive decline and neurodegenerative *** article also summarizes the gut microbiota components that affect astrocyte function,mainly through the vagus nerve,immune responses,circadian rhythms,and microbial ***,this article summarizes the mechanism by which the gut microbiota–astrocyte axis plays a role in Alzheimer’s and Parkinson’s *** findings have revealed the critical role of the microbiota–astrocyte axis in age-related cognitive decline,aiding in a deeper understanding of potential gut microbiome-based adjuvant therapy strategies for this condition.

关键词： age aging Alzheimer’s disease astrocytes cognitive decline dementia gut microbiota gut–brain axis microbial metabolites neuroinflammation Parkinson’s disease

Response of ecosystem Respiration to Experimental Warming and Clipping at Daily Time Scale in an Alpine Meadow of Tibet

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2013年第3期10卷 455-463页

作者： FU Gang SHEN Zhen-xi ZHANG Xian-zhou YU Cheng-qun ZHOU Yu-ting LI Yun-long YANG Peng-wan Lhasa Plateau ecosystem research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences University of Chinese Academy of Sciences

The alpine meadow, as one of the typical vegetation types on the Tibetan Plateau, is one of the most sensitive terrestrial ecosystems to climate warming. However, how climate warming affects the carbon cycling of the alpine meadow on the Tibetan Plateau is not very dear. A field experiment under controlled experimental warming and clipping conditions was conducted in an alpine meadow on the Northern Tibetan Plateau since July 2008. Open top chambers （0TCs） were used to simulate climate warming. The main objective of this study was to examine the responses of ecosystem respiration （Reco） and its temperature sensitivity to experimental warming and clipping at daily time scale. Therefore, we measured Reco once or twice a month from July to September in 2010, from June to September in 2011 and from August to September in 2012. Air temperature dominated daily variation of Reco whether or not experimental warming and clipping were present. Air temperature was exponentially correlated with Reco and it could significantly explain 58-96% variation of Redo at daily time scale. Experimental warming and clipping decreased daily mean Reco by 5.8-37.7% and -11.9-23.0%, respectively, although not all these changes were significant. Experimental warming tended to decrease the temperature sensitivity of Reco, whereas clipping tended to increase the temperature sensitivity of Reco at daily time scale. Our findings suggest that Reco wasmainly controlled by air temperature and may acclimate to climate warming due to its lower temperature sensitivity under experimental warming at daily time scale.

关键词： Acclimation Air temperature Open topchamber Temperature sensitivity Respirationquotient ( Q10)

Clipping Alters the Response of Biomass Production to Experimental Warming: A Case Study in an Alpine Meadow on the Tibetan Plateau, China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2015年第4期12卷 935-942页

作者： FU Gang SUN Wei YU Cheng-Qun ZHANG Xian-Zhou SHEN Zhen-Xi LI Yun-Long YANG Peng-Wan ZHOU Nan Lhasa Plateau ecosystem research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences

Predicting how human activity will influence the response of alpine grasslands to future warming has many *** this study, a field experiment with controlled warming and clipping was conducted in an alpine meadow at three elevations（4313 m, 4513 m and 4693 m） in Northern Tibet to test the hypothesis that clipping would alter warming effect on biomass *** top chambers（OTCs） were used to increase temperature since July,2008 and the OTCs increased air temperature by approximately 0.9o C ~ 1.8o C during the growing *** was conducted three times one year during growing season and the aboveground parts of all live plants were clipped to approximately 0.01 m in height using scissors since *** primary production（GPP） was calculated from the Moderate-Resolution Imaging Spectroradiometer GPP algorithm and aboveground plant production was estimated using the surface-measured normalized difference vegetation index in *** decreased the GPP, aboveground biomass（AGB） and aboveground net primary production（ANPP） at all three elevations when clipping was not *** contrast, warming increased AGB at all three elevations, GPP at the two lower elevations and ANPP at the two higher elevations when clipping was *** findings show that clipping reduced the negative effect of warming on GPP, AGB and ANPP, suggesting that clipping may reduce the effect of climate warming on GPP, AGB and ANPP in alpine meadows on the Tibetan Plateau, and therefore, may be a viable strategy for mitigating the effects of climate change on grazing and animal husbandry on the Tibetan Plateau.

关键词： Clipping Gross primary production Open top chamber Warming Alpine Meadow Tibetan Plateau

Habitat preferences of diurnal raptors in relation to human access to their breeding territories in the Balkan Mountain Range,Bulgaria

在线全文

学校读者我要写书评

暂无评论

Avian research 2021年第3期12卷 307-316页

作者： Nadejda Djorgova Dimitar Ragyov Valko Biserkov Jordan Biserkov Boris P.Nikolov institute of Biodiversity and ecosystem research Bulgarian Academy of Sciences2 Gagarin Street1113 SofiaBulgaria

Background:In this study we examined the habitat preferences of three diurnal raptors in relation to human *** aimed to identify the selection of breeding habitat by the Golden Eagle(Aquila chrysaetos),the Long-legged Buz-zard(Buteo rufinus),and the Peregrine Falcon(Falco peregrinus)in response to site accessibility by humans,and in turn,the response of these species to human ***:Data about the nest locations were *** and maps were created using ***“least cost path”was defined using the Cost Path ***:The lowest values of the Cost Path were established for Long-legged Buzzard and the highest values were estimated for Golden *** Cost Path values for Peregrine Falcon were ***:The Long-legged Buzzard could be considered as the most tolerant to human presence in its breeding *** Golden Eagle have the lowest degree of tolerance and the Peregrine Falcon is ranked in an intermedi-ate position compared to the other two species,but closer to Golden Eagle.

关键词： Anthropogenic impact Golden Eagle Least cost path Long-legged Buzzard Peregrine Falcon

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China,2004-2010

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2013年第5期25卷 1007-1014页

作者： Xinyu Zhang Zhiwei Xu Xiaomin Sun Wenyi Dong Deborah Ballantine Key Laboratory of ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences National institute of Water and Atmospheric research HamiltonNew Zealand

The nitrate-nitrogen（NO 3-N） concentrations from shallow groundwater wells situated in 29 of the Chinese ecosystem research Network field stations,representing typical agroand forest ecosystems,were assessed using monitoring data collected between 2004 and *** from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater,and allow linkages between nitrate concentrations in groundwater and broad land use categories to be *** indicated that most of the NO 3--N concentrations in groundwater from the agroand forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard：Quality Standard for Ground Water（≤ 20 mg/L）.Over the study period,the average NO 3--N concentrations were significantly higher in agro-ecosystems（4.1 ± 0.33 mg/L） than in forest ecosystems（0.5 ± 0.04 mg/L）.NO 3-N concentrations were relatively higher（〉 10 mg N /L） in 10 of the 43 wells sampled in the agricultural *** elevated concentrations occurred mainly in the Ansai,Yucheng,Linze,Fukang,Akesu,and Cele field sites,which were located in arid and semiarid areas where irrigation rates are *** suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

关键词： Chinese ecosystem research Network shallow groundwater agricultural forest ecosystems nitrate concentration

Effects of livestock exclusion and climate change on aboveground biomass accumulation in alpine pastures across the Northern Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第32期59卷 4332-4340页

作者： Jianshuang Wu Xianzhou Zhang Zhenxi Shen Peili Shi Chengqun Yu Baoxiong Chen Lhasa Plateau ecosystem research Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences

To better understand the ecological and economic benefits of short-term grazing exclusion on the aboveground net primary productivity(ANPP)of alpine pastures,we conducted annual multi-site transect surveys in the summers from 2009 to 2011 and calculated the aboveground biomass discrepancy(ABD)between grazed and ungrazed pastures at plant community and economic group levels for three zonal alpine grassland types—meadow,steppe,and desert-steppe—across the northern Tibetan *** results indicated that aboveground biomass(AGB)significantly differed among grassland types and declined northwesterly from 64.07 to11.44 g m-2with decreasing precipitation and increasing *** mean ABD exhibited considerable community dependency,with meadow(12.47 g m-2)[steppe(6.91 g m-2)[desert steppe(2.54 g m-2),and it declined from 25.42 to 1.29 g m-2with decreasing precipitation and increasing temperature.‘Good forage’,*** and sedges,benefited most from grazing exclusion,followed by edible *** longer grazing exclusion durations(GEDs),the aboveground biomass of poisonous locoweeds initially decreased and then increased compared with the adjacent grazed *** the nested analysis of co-variances with a general linear model,growing season precipitation(GSP;from May to September)accounted for 52.67%ofthe observed variation in AGB,followed by AGT(9.77%)and pasture management systems(PMSs;grazing or grazing-excluded,5.31%).The variation in ABD was explained primarily by AGT(16.52%),GED(20.25%),and the interaction of AGT 9 GED(19.58%).Our results confirm that precipitation is the primary factor controlling the ANPP of alpine grasslands on the Northern Tibetan Plateau and that the ecological benefits arising from grazing exclusion are also partly dependent on grassland type and exclusion ***,spatial and temporal variations in growing season precipitation and plant functional traits or economic group composition should be jointly considered when devel

关键词：地上生物量藏北高原生物量积累牧场高山气候变化荒漠草原牲畜

Forest structure and anthropogenic pressures in the Pachmarhi biosphere reserve of India

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry research 2015年第4期26卷 867-874页

作者： Chandra Prakash Kala ecosystem & Environment Management Indian Institute of Forest Management

A critical first step in establishing biosphere reserves--under the Man and Biosphere Programme of UNESCO--is to generate baseline information for future courses of action. The present study aims to assess the structure and composition of forests--along with anthro- pogenic pressures mounting on these forests in the buffer zone of one such biosphere reserves--the Pachmarhi bio- sphere reserve of India. The quadrat method was employed for sampling vegetation, and information on anthropogenic pressures was collected by conducting interviews with local people and forest officials and collecting it from secondary sources. A total of 39 tree species were sampled in 82 quadrats; of these 26 tree species were in standing stage, 25 in sapling, and 35 in seedling. Chloroxylon swi- etenia emerged as the most dominant tree species having highest importance value index, followed by Tectona grandis, Terminalia tomentosa, and Hardwickia binata. Nine tree species and their saplings, including Sterculia urens and Terminalia arjuna, were exploited so badly that they were only found in the seedlings stage. The unavail- ability of standing trees of 12 important tree species including Aegle marmelos and Phyllanthus emblicaindicates the intensity and gravity of anthropogenic pres- sures on these important tree species. If the present anthropogenic pressure continues, which has inhibited the regeneration of several tree species, then substantial neg- ative ecological and societal consequences can be expected.

关键词： Pachmarhi biosphere reserve Tropicalforest Forest composition Forest structure Regeneration Anthropogenic pressures

Introduction to the China Jellyfish Project——The Key Processes,Mechanism and Ecological Consequences of Jellyfish Bloom in China Coastal Waters

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Oceanology and Limnology 2011年第2期29卷 491-492页

作者：孙晓霞王世伟孙松 Jiaozhou Bay Marine ecosystem research Station Institute of OceanologyChinese Academy of Sciences

As a National Basic research Program (973 Program) of China, the Key Processes, Mechanism and Ecological Consequences of Jellyfish Bloom in China Coastal Waters led by Prof. SUN

关键词：中国科学院沿海水域生态后果水母机理 973计划基础研究关键工序