科尔沁沙地124种天然植物粘液繁殖体的甄别   总被引：5，自引：0，他引：5  

刘志民  闫巧玲  骆永明  王红梅  蒋德明 《中国沙漠》2005,25(5):716-721

用粘沙法对科尔沁沙地西部124种天然植物进行了粘液繁殖体甄别。结果表明:(1)在124种植物中,有13种植物包括冷蒿(Artemisiafrigida)、万年蒿(A.gmelinii)、差不嘎蒿(A.halodendron)、野艾蒿(A.lavan-dulaefolia)、大籽蒿(A.sieversiana)、黄蒿(A.scoparia)、乌丹蒿(A.wudanica)、画眉(Eragrostispilosa)、小画眉(E.poaeoides)、百里香(Thymusmongolicus)、平车前(Plantagodepressa)、盐生车前(Plantagomaritima)、野亚麻(Linumstelleroides)的种子分泌粘液,占所有被测植物的10.5%;(2)综合浇水2mm和水浸20min两种处理结果发现,盐生车前、平车前、乌丹蒿、冷蒿、百里香粘液(粘沙)繁殖体比例很高,万年蒿、黄蒿、野艾蒿粘液繁殖体比例相对低;(3)综合浇水2mm和水浸20min处理结果发现,分泌粘液粘沙后重量变化较大的植物包括画眉、小画眉、盐生车前、乌丹蒿、万年蒿;(4)将水浸20min与浇水20mm处理的结果进行平均,得到的粘沙种子总粘沙量由小到大的顺序是:黄蒿 < 野艾蒿 < 万年蒿 < 小画眉 < 画眉 < 冷蒿 < 差不嘎蒿 < 大籽蒿 < 百里香 < 野亚麻 < 平车前 < 乌丹蒿 < 盐生车前;(5)全部13种有粘液繁殖体植物的种子均小,单粒重小于1mg;(6)无论对水浸20min,还是浇水20mm处理,粘沙种子粘沙量与未粘沙种子重量正相关,即种子越大,粘沙量越大;(7)蒿属植物占具有粘液繁殖体植物的比例较大,供试的7种植物均有种子分泌粘液,但在粘沙种子重量增加量、粘沙种子对未粘沙种子的重量倍数、粘沙种子百分数等方面表现物种间差异;(8)蒿属植物分泌粘液是其适应流沙的属性之一。  相似文献   

“一带一路”沿线国家适应气候变化的技术需求评估     

高美勋  陈敏鹏  滕飞 《气候变化研究进展》2022,18(6):731-742

“一带一路”沿线国家受气候变化影响严重,亟需从其他国家转移适当的适应气候变化技术。技术需求评估是有效开展技术转移的必要前提。本研究利用“一带一路”沿线国家完成提交给《联合国气候变化框架公约》的技术需求评估（TNA）报告,在合作专利分类（CPC）框架下建立适应优先技术需求数据库,并根据技术需求的提及次数、技术需求的国家数目、技术需求的GDP覆盖范围以及技术惠及人口4个指标,分别从技术和地区两个角度对“一带一路”沿线国家的适应技术需求开展评估。结果发现：一方面,农林牧副渔生产中的适应技术（Y02A-40),集水、节水与高效利用水的技术（Y02A-20),沿海地区与江河流域的适应技术（Y02A-10）与对适应气候变化有间接贡献的技术（Y02A-90）这4方面的适应技术是“一带一路”沿线国家普遍关切的技术需求。另一方面,不同地区的“一带一路”沿线国家因其特有的地理区位和社会经济情况不同而产生特殊的适应技术需求。大洋洲、拉丁美洲与加勒比地区以及亚洲地区部分国家由于国内基础设施受气候变化影响十分严重,提出了保护和改造基础设施建设的技术（Y02A-30）需求;受气候变化影响,高温和降水加剧了疾病在空气和水体的传播,因此亚洲地区,大洋洲、拉丁美洲与加勒比地区特别提出了应对极端天气、保护人类健康的技术（Y02A-50）需求。为促进“一带一路”沿线国家开展有效技术转移,提高应对气候变化能力,应加大对气候适应技术研发投入,以技术接受国的技术需求为基础,并高效利用现有的“一带一路”技术转移中心网络,开展技术转移活动。  相似文献   

Hydraulic traits that buffer deep-rooted plants from changes in hydrology and climate     

Kevin R. Hultine  Ray Froend  Davis Blasini  Susan E. Bush  Melissa Karlinski  Dan F. Koepke 《水文研究》2020,34(2):209-222

Groundwater-dependent ecosystems are often defined by the presence of deeply rooted phreatophytic plants. When connected to groundwater, phreatophytes in arid regions decouple ecosystem net primary productivity from precipitation, underscoring a disproportionately high biodiversity and exchange of resources relative to surrounding areas. However, groundwater-dependent ecosystems are widely threatened due to the effects of water diversions, groundwater abstraction, and higher frequencies of episodic drought and heat waves. The resilience of these ecosystems to shifting ecohydrological–climatological conditions will depend largely on the capacity of dominant, phreatophytic plants to cope with dramatic reductions in water availability and increases in atmospheric water demand. This paper disentangles the broad range of hydraulic traits expressed by phreatophytic vegetation to better understand their capacity to survive or even thrive under shifting ecohydrological conditions. We focus on three elements of plant water relations: (a) hydraulic architecture (including root area to leaf area ratios and rooting depth), (b) xylem structure and function, and (c) stomatal regulation. We place the expression of these traits across a continuum of phreatophytic habits from obligate to semi-obligate to semi-facultative to facultative. Although many species occupy multiple phreatophytic niches depending on access to groundwater, we anticipate that populations are largely locally adapted to a narrow range of ecohydrological conditions regardless of gene flow across ecohydrological gradients. Consequently, we hypothesize that reductions in available groundwater and increases in atmospheric water demand will result in either (a) stand replacement of obligate phreatophytic species with more facultative species as a function of widespread mortality in highly groundwater-dependent populations or (b) directional selection in semi-obligate and semi-facultative phreatophytes towards the expression of traits associated with highly facultative phreatophytes in the absence of species replacement. Anticipated shifts in the expression of hydraulic traits may have profound impacts on water cycling processes, species assemblages, and habitat structure of groundwater-dependent woodlands and riparian forests.  相似文献   

高分五号高光谱影像的关联对齐域适应与分类     

彭江涛  孙伟伟  魏天慧  范文琦 《遥感学报》2020,24(4):417-426

高分五号(GF-5)搭载的高光谱传感器兼顾宽覆盖和高分辨率的特性,但在实际应用中宽覆盖范围内各种地物类别的标注十分困难。当标记样本很少甚至没有标记样本时,遥感图像分类异常困难。此时,可以采用域适应方法,借助已标记的历史数据(源域)实现对未标记数据(目标域)的分类。本文提出了一种基于稀疏矩阵变换的关联对齐域适应分类算法。首先,利用稀疏矩阵变换估计源域和目标域的协方差矩阵;然后,运用协方差关联对齐方法估计源域到目标域的变换矩阵;接着,运用估计得到的变换矩阵将源域数据进行变换,使得其与目标域对齐;最后,在变换后的源域数据上建立分类器,实现对目标域数据的分类。本文的算法在两个真实的GF-5高光谱数据集上进行了验证。实验结果表明,本文算法要优于常用的子空间对齐算法和关联对齐算法。特别地,在黄河口GF-5数据上,本文算法比原始关联对齐方法的最近邻分类准确率提升了3.5%,支持向量机分类准确率提升了2.3%。  相似文献   

Urban resilience for whom,what, when,where, and why?     

Sara Meerow  Joshua P. Newell 《Urban geography》2019,40(3):309-329

ABSTRACT

In academic and policy discourse, the concept of urban resilience is proliferating. Social theorists, especially human geographers, have rightfully criticized that the underlying politics of resilience have been ignored and stress the importance of asking “resilience of what, to what, and for whom?” This paper calls for careful consideration of not just resilience for whom and what, but also where, when, and why. A three-phase process is introduced to enable these “five Ws” to be negotiated collectively and to engender critical reflection on the politics of urban resilience as plans, initiatives, and projects are conceived, discussed, and implemented. Deployed through the hypothetical case of green infrastructure in Los Angeles, the paper concludes by illustrating how resilience planning trade-offs and decisions affect outcomes over space and time, often with significant implications for equity.  相似文献   

Modelling blue and green water availability under climate change in the Beninese Basin of the Niger River Basin,West Africa          下载免费PDF全文

Djigbo Félicien Badou  Bernd Diekkrüger  Evison Kapangaziwiri  Mamadou L. Mbaye  Yacouba Yira  Emmanuel A. Lawin  Ganiyu T. Oyerinde  Abel Afouda 《水文研究》2018,32(16):2526-2542

The aim of this study was to quantify climate change impact on future blue water (BW) and green water (GW) resources as well as the associated uncertainties for 4 subbasins of the Beninese part of the Niger River Basin. The outputs of 3 regional climate models (HIRHAM5, RCSM, and RCA4) under 2 emission scenarios (RCP4.5 and RCP8.5) were downscaled for the historical period (1976–2005) and for the future (2021–2050) using the Statistical DownScaling Model (SDSM). Comparison of climate variables between these 2 periods suggests that rainfall will increase (1.7% to 23.4%) for HIRHAM5 and RCSM under both RCPs but shows mixed trends (?8.5% to 17.3%) for RCA4. Mean temperature will also increase up to 0.48 °C for HIRHAM5 and RCSM but decrease for RCA4 up to ?0.37 °C. Driven by the downscaled climate data, future BW and GW were evaluated with hydrological models validated with streamflow and soil moisture, respectively. The results indicate that GW will increase in all the 4 investigated subbasins, whereas BW will only increase in one subbasin. The overall uncertainty associated with the evaluation of the future BW and GW was quantified through the computation of the interquartile range of the total number of model realizations (combinations of regional climate models and selected hydrological models) for each subbasin. The results show larger uncertainty for the quantification of BW than GW. To cope with the projected decrease in BW that could adversely impact the livelihoods and food security of the local population, recommendations for the development of adequate adaptation strategies are briefly discussed.  相似文献   

偏顶蛤（Modiolus modiolus）转录组组装及其与深海偏顶蛤（Bathymodiolus platifrons）比较转录组研究     

孟杰  杨梅  许飞  李新正  李莉 《海洋学报(英文版)》2018,37(8):38-45

双壳类适应性进化遗传基础尚未有大量研究。而生活在沿海潮间带和深海环境中的双壳贝类适应性进化的分子机制更鲜有报道。我们首次测序组装了潮间带生活的偏顶蛤Modiolus modiolus的转录组序列。同时与生活在深海热液冷泉喷口的偏顶蛤Bathymodiolus platifrons进行了比较转录组分析，阐明了这两个物种在不同环境中的适应性进化机制。M. modiolus和B. platifrons的转录组组装共产生182，476和156，261个转录本，N50值分别为1，769和1，545。同时注释到27，868和23，588个基因。GO富集分析表明这些基因有相似的富集模式。两物种进化分析鉴定到10，245个直系同源基因，其中26个基因受到强烈正选择（Ka/Ks＞1），12个基因受到中度正选择（0.5M. modiolus的转录组组装拼接序列，同时通过比较转录组学分析阐明了其与近缘物种B. platifrons的适应性进化机制。这为两个物种后续研究提供了序列资源和研究基础。  相似文献   

Vulnerability and adaptation of an oasis social–ecological system affected by glacier change in an arid region of northwestern China     

JianPing Yang  Man Li  ChunPing Tan  HongJu Chen  Qin Ji 《寒旱区科学》2019,11(1):29-40

The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 16 indicators from natural and socioeconomic systems according to exposure, sensitivity, and adaptive capacity; and construct a vulnerability-assessment indicator system aimed at an inland river basin in the arid region of Northwestern China. Vulnerability of the oasis socialecological system affected by glacier change in the study area is evaluated by Spatial Principal Component Analysis(SPCA) under the circumstance of glacier change. The key factors affecting the vulnerability are analyzed. The vulnerability of the oasis social-ecological system in the Hexi Inland River Basin affected by glacier change is of more than medium grade, accounting for about 48.0% of the total number of counties in the study area. In terms of the spatial pattern of the vulnerability, the oasis economic belt is the most vulnerable. With the rapid development of the area's society and economy, the exposure of the system to glacial changes is significantly increased; and an increase in glacial meltwater is not enough to overcome the impact of increased exposure, which is the main reason for the high vulnerability. Based on the result of the vulnerability analysis and combined with the present industrial structure in the Hexi Inland River Basin, near-,medium-, and long-term adaptation initiatives are put forward in the article.  相似文献   

ON A POSSIBLE MECHANISM FOR SOUTHERN ASIAN CONVECTION INFLUENCING THE SOUTH ASIAN HIGH ESTABLISHMENT DURING WINTER TO SUMMER TRANSITION   总被引：3，自引：0，他引：3  

刘伯奇  何金海  王黎娟 《热带气象学报(英文版)》2012,18(4):473-484

The establishment of the South-Asian high (SAH) in April and May over the Indochina Peninsula (IP) is investigated based on the ERA-40 reanalysis data. The result shows that the SAH is generated and strengthened over the IP locally, rather than moving westward to the IP from the Western Pacific. After the SAH establishment the tropical upper tropospheric trough (TUTT) forms above the ocean to the east of the Philippines. We have found that the principal triggering factor of both the SAH construction and the TUTT formation is the variation in the Southern Asian atmospheric diabatic heating regime. In late April, both the climbing effect of Shan Plateau and the local surface sensible heating contribute to local rainfall over the IP. Then the local updraft and upper-air divergence are strengthened, being responsible for the SAH formed in the southern part of the IP. As convection moves northward along the Australian-Asian "maritime continent" and the Bay of Bengal (BoB) summer monsoon begins, the convection is intensified in May on the eastern BoB. The strong convection results in the SAH enhancing and expanding westward, accompanied by reinforced meridional flow to the east of SAH, where responses of the circulation to diabatic heating arrive at a quasi-steady state. Meanwhile, because of the positive geopotential vorticity advection resulting from upper equatorward flow, the local positive relative vorticity increases over the ocean to the east of the Philippines, making the tropical upper tropospheric trough (TUTT) form around 150°E.  相似文献   

全球化背景下国际移民社会融合研究综述与展望     

黄旭  刘怀宽  薛德升 《世界地理研究》2020,29(2):397-405

21世纪以来，全球化进程加速，国际移民成为研究热点问题，而当前欧美学界针对移民社会融合的研究具有三方面特征：首先，国际移民社会融合的维度呈现多样化；其次，移民社会融合的主动性及其对社区空间的塑造作用成为研究热点；最后，研究视角存在“方法论上的民族主义”和“政治正确的价值倾向”。与之相对，国内学界对国际移民社会融合的研究能够准确地把握国家背景、政治制度、移民政策对移民社会融合的影响作用；以及在全球化背景下国际移民在世界城市快速流动的旅居者特性，且充分注意到移民的多元性和融合的开放性。而不足之处在于，缺少对于社会融合多尺度、多维度的探讨；缺乏对于不同族裔、不同类型的移民群体间社会融合路径、模式、机制的比较。新形势下，国内研究有必要超越西方学者的思考，探讨国际移民社会融合的中国路径，为我国城市解决全球化带来的国际移民融合问题提供新思路。  相似文献