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《中国生物化学与分子生物学报》1999,15(4):537-537
Atthe18thInternationalCongressofBiochemistryandMolecularBiology,Birmingham,EnglandTheInternationalUnionofBiochemistryandMolecularBiology(IUBMB),theFederationofEuropeanBiochemicalSocieties(FEBS),andtheBiochemicalSocietyannouncethesponsorshipofaSympos… 相似文献
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1 Source ThesequencewasdeterminedfromaPCR product,whichwasligatedtopBluescriptSK( )vecter (namedaspSN) ,fromthechloroplastgenomicDNAofBrassicanapus(Oilseedrape)cv.H1 65.2 Nameanddescription Brassicanapuschloro plastgenendhBis 2 4 67bplongwithtwoexonsthatencode 51 0a… 相似文献
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《Acta Botanica Sinica》2002,(9)
ActaBotanicaSinicaistheofficialpublicationofBotanicalSocietyofChina .Foundedin 195 2 ,ithasbecomeamonthlyjournal.Itpublishesoriginalp 相似文献
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《Acta Botanica Sinica》2002,(2)
ActaBotanicaSinicaistheofficialpublicationofBotanicalSocietyofChina .Foundedin 195 2 ,ithasbecomeamonthlyjournal.Itpublishesoriginalp 相似文献
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《Acta Botanica Sinica》2002,(3)
ActaBotanicaSinicaistheofficialpublicationofBotanicalSocietyofChina .Foundedin 195 2 ,ithasbecomeamonthlyjournal.Itpublishesoriginalp 相似文献
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Precipitation and streamflow have been measured in three small (0.04–0.52 km2) experimental catchments covered by dense holm oak (Quercus ilex L.) forests. Two of them are in the Prades mountains and one in the Montseny mountains (NE Spain). Here we test the hydrological representativeness of these catchments against the streamflow record at two nearby larger (34–60 km2) catchments, one from each massif. Comparisons of (i) annual streamflow, (ii) seasonal distribution of streamflow, and (iii) flow duration curves were made. At Prades, for the period of common record, mean annual precipitation was about 580 mm, and mean annual streamflow 44–81 mm at the two experimental catchments and 102 mm at the larger one. Most streamflow occurred during winter and spring in the three catchments. At Montseny, rainfall was higher, and mean annual streamflow was 495 mm in the experimental catchment, and 760 mm in the larger catchment, though these data were obtained in different periods in each catchment. Streamflow was roughly equal in autumn, winter and spring. At both sites flow duration curves were fairly similar in the small experimental catchments and the larger catchments. The higher streamflow at Montseny is reflected in its flow duration curves being well above those at Prades. The experimental catchments at Prades are thus fairly representative of the larger nearby catchment for the investigated hydrological characteristics. At Montseny, hydrological differences between the experimental catchment and the larger catchment are probably due to the higher mean altitude of the latter and to the non-overlapping periods of their streamflow records. 相似文献
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To clarify the sediment yield processes following a disturbance by a forest fire in a mountainous catchment, and considering the hydrological and geomorphological processes in the headwater, we measured bedload sediment yield at rainfall events in disturbed and secondary forest catchments in the western part of Japan. The three catchments were under different hydrogeological conditions. The IK, TB and TY catchments were disturbed by forest fires in 2000, 1994, and 1978, respectively. In the IK catchment, although runoff response to rainfall was fastest with high peak flows, the catchment also had the highest base flow. Moreover, the annual sediment yield there was about ten times as high as in the other two catchments, and it was found that there was a steep linear curve in the relationship between precipitation and bedload sediment yield. This is thought to be caused by overland flow generation following water repellency on the slopes, and by the accumulated sediment that forms the thick soil layer on the valley bottom. On the other hand, in the TB catchment runoff experienced high peak flows at rainfall events and low base flows, and there was a gradual linear curve in the precipitation–sediment yield relationship. This might be the result of there being a thin soil layer on the hillslope and on the valley bottom because of successive erosion after the fire. In the TY catchment, runoff had a low peak flow at rainfall events and a high base flow; and the bedload sediment yield increased exponentially with increasing precipitation. Therefore, sediment yield in the TB catchment was more than that in the TY during storm events with precipitation of less than 100 mm, whereas it was the opposite during heavier rainfalls. It indicates that there is a thick soil layer on the slope and a thin soil layer on the valley bottom in the TY catchment following the recovering of vegetation, and that the sediment yield process predominates only during big rainfall events, only then does subsurface flow generate. 相似文献
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广东小良水保站三种生态系统地表侵蚀的研究 总被引:8,自引:0,他引:8
在系统地研究了广东小良水保站的混交林,桉树林,裸地等三种生态系统类型的水文效益以后,本文着重探讨了它们的水土保持效益。结果表明裸地的降雨侵蚀率分别是桉树林的5.2倍,是混交林的228.1倍;径流侵蚀率裸地是桉树林的11.3倍,是混交林的31.9倍。从总体上来看,无论是降雨侵蚀率还是径流侵蚀率都是混交林的最小,而且从侵蚀物的组成来看,混交林地表径流中的悬浮物占较大的比重。侵蚀物与降雨量存在x=f(PA)的相关关系,A的大小反映了降雨对侵蚀的影响程度,不同的土壤是不同的,混交林A<1,桉树林A=1.48,裸地A=1.85,侵蚀率的年间变化以混交林的最大。用灰色系统的GM(2,1)模型,本文较为成功地预测了年际间的侵蚀率。 相似文献
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植被的降雨分配作用对理解生态系统的水文功能具有重要的意义。该文对四川岷江上游岷江冷杉(Abies faxoniana)针叶林和川滇高山栎(Quercus aquifolioides)灌丛两种生态系统的降雨分配及降雨截留的影响因素进行了研究,探讨了植被分配降雨及截留降雨的影响机制和影响因素。文中采用定位观测的方法研究降雨分配。针叶林中冠层降雨截留占33.33%,树干茎流占0.07%,穿透雨占66.60%;而灌丛的冠层截留降雨为24.95%,穿透雨为75.05%;针叶林地被物的蓄留水能力(1.746 mm)要大于灌丛地被物的持水能力(0.941 mm);针叶林土壤的容积含水率(39.66%)也要高于灌丛土壤的容积含水率(38.19%);两种生态系统中的穿透雨率与降雨量的关系均可用逻辑斯谛方程较好地模拟。文中还选取了降雨量、降雨强度、降雨持续时间、两次降雨的间隔时间和次降雨期间的气温等5种因子分析影响两种生态系统降雨截留的主要因素。根据截留降雨与上述5种因子的偏相关分析结果:针叶林冠层的降雨截留主要受降雨量、降雨持续时间和间隔时间的影响;灌丛的降雨截留主要受降雨量、气温与降雨持续时间的影响。文中从当地的降雨特征与两种生态系统微气候差异的角度分析了两种生态系统降雨分配及降雨截留影响因素差异的原因。 相似文献
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漓江上游典型森林植被对降水径流的调节作用 总被引:3,自引:0,他引:3
利用野外同步长期定位观测林外降雨、地表径流和河川径流的方法,对漓江上游典型森林植被的生态水文过程进行观测研究。结果表明:1)流域降水年内分配极不均匀,50a年降雨量总体变化趋势不明显。林冠截留受林外降雨特征的影响,也与植被类型密切相关。2)地表径流平均滞后时间为70 min。在连续降雨的情况下,降雨滞后效应不再明显,甚至出现地表径流与降雨同步的现象,小降雨可能产生大的地表径流,从而加大流域在雨季发生洪灾的风险。3)湿季径流系数略大于旱季,干季降水量减少,且森林植被消耗大量水分,减少了枯水期径流的产生,增大发生旱灾的风险。森林植被延长河川径流持续时间,使一次持续18 d的降水过程形成的径流,在降水停止后能延续24 d。降雨后退水持续时间与前期降水及后期降水叠加有关。目的为揭示漓江上游森林植被对降水径流的调节作用,客观评估漓江上游水资源潜力、加强流域水资源管理和森林经营提供科学依据。 相似文献
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Forests growing under dry conditions have higher hydrological resilience to drought than do more humid forests 总被引:1,自引:0,他引:1
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More frequent and intense droughts are projected during the next century, potentially changing the hydrological balances in many forested catchments. Although the impacts of droughts on forest functionality have been vastly studied, little attention has been given to studying the effect of droughts on forest hydrology. Here, we use the Budyko framework and two recently introduced Budyko metrics (deviation and elasticity) to study the changes in the water yields (rainfall minus evapotranspiration) of forested catchments following a climatic drought (2006–2010) in pine forests distributed along a rainfall gradient (P = 280–820 mm yr?1) in the Eastern Mediterranean (aridity factor = 0.17–0.56). We use a satellite‐based model and meteorological information to calculate the Budyko metrics. The relative water yield ranged from 48% to 8% (from the rainfall) in humid to dry forests and was mainly associated with rainfall amount (increasing with increased rainfall amount) and bedrock type (higher on hard bedrocks). Forest elasticity was larger in forests growing under drier conditions, implying that drier forests have more predictable responses to drought, according to the Budyko framework, compared to forests growing under more humid conditions. In this context, younger forests were shown more elastic than older forests. Dynamic deviation, which is defined as the water yield departure from the Budyko curve, was positive in all forests (i.e., less‐than‐expected water yields according to Budyko's curve), increasing with drought severity, suggesting lower hydrological resistance to drought in forests suffering from larger rainfall reductions. However, the dynamic deviation significantly decreased in forests that experienced relatively cooler conditions during the drought period. Our results suggest that forests growing under permanent dry conditions might develop a range of hydrological and eco‐physiological adjustments to drought leading to higher hydrological resilience. In the context of predicted climate change, such adjustments are key factors in sustaining forested catchments in water‐limited regions. 相似文献
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Patterns and Dynamics of Dissolved Organic Carbon (DOC) in Boreal Streams: The Role of Processes,Connectivity, and Scaling 总被引:2,自引:0,他引:2
Hjalmar Laudon Martin Berggren Anneli Ågren Ishi Buffam Kevin Bishop Thomas Grabs Mats Jansson Stephan Köhler 《Ecosystems》2011,14(6):880-893
We bring together three decades of research from a boreal catchment to facilitate an improved mechanistic understanding of
surface water dissolved organic carbon (DOC) regulation across multiple scales. The Krycklan Catchment Study encompasses 15
monitored nested research catchments, ranging from 3 to 6900 ha in size, as well as a set of monitored transects of forested
and wetland soils. We show that in small homogenous catchments, hydrological functioning provides a first order control on
the temporal variability of stream water DOC. In larger, more heterogeneous catchments, stream water DOC dynamics are regulated
by the combined effect of hydrological mechanisms and the proportion of major landscape elements, such as wetland and forested
areas. As a consequence, streams with heterogeneous catchments undergo a temporal switch in the DOC source. In a typical boreal
catchment covered by 10-20% wetlands, DOC originates predominantly from wetland sources during low flow conditions. During
high flow, the major source of DOC is from forested areas of the catchment. We demonstrate that by connecting knowledge about
DOC sources in the landscape with detailed hydrological process understanding, an improved representation of stream water
DOC regulation can be provided. The purpose of this study is to serve as a framework for appreciating the role of regulating
mechanisms, connectivity and scaling for understanding the pattern and dynamics of surface water DOC across complex landscapes.
The results from this study suggest that the sensitivity of stream water DOC in the boreal landscape ultimately depends on
changes within individual landscape elements, the proportion and connectivity of these affected landscape elements, and how
these changes are propagated downstream. 相似文献
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Kevin W. Turner Brent B. Wolfe Thomas W. D. Edwards Trevor C. Lantz Roland I. Hall Guillaume Larocque 《Global Change Biology》2014,20(5):1585-1603
Many northern lake‐rich regions are undergoing pronounced hydrological change, yet inadequate knowledge of the drivers of these landscape‐scale responses hampers our ability to predict future conditions. We address this challenge in the thermokarst landscape of Old Crow Flats (OCF) using a combination of remote sensing imagery and monitoring of stable isotope compositions of lake waters over three thaw seasons (2007–2009). Quantitative analysis confirmed that the hydrological behavior of lakes is strongly influenced by catchment vegetation and physiography. Catchments of snowmelt‐dominated lakes, typically located in southern peripheral areas of OCF, encompass high proportions of woodland/forest and tall shrub vegetation (mean percent land cover = ca. 60%). These land cover types effectively capture snow and generate abundant snowmelt runoff that offsets lake water evaporation. Rainfall‐dominated lakes that are not strongly influenced by evaporation are typically located in eastern and northern OCF where their catchments have higher proportions of dwarf shrub/herbaceous and sparse vegetation (ca. 45%), as well as surface water (ca. 20%). Evaporation‐dominated lakes, are located in the OCF interior where their catchments are distinguished by substantially higher lake area to catchment area ratios (LA/CA = ca. 29%) compared to low evaporation‐influenced rainfall‐dominated (ca. 10%) and snowmelt‐dominated (ca. 4%) lakes. Lakes whose catchments contain >75% combined dwarf shrub/herbaceous vegetation and surface water are most susceptible to evaporative lake‐level drawdown, especially following periods of low precipitation. Findings indicate that multiple hydrological trajectories are probable in response to climate‐driven changes in precipitation amount and seasonality, vegetation composition, and thermokarst processes. These will likely include a shift to greater snowmelt influence in catchments experiencing expansion of tall shrubs, greater influence from evaporation in catchments having higher proportions of surface water, and an increase in the rate of thermokarst lake expansion and probability of drainage. Local observations suggest that some of these changes are already underway. 相似文献
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荒漠草原中间锦鸡儿冠层截留特征 总被引:2,自引:1,他引:1
以荒漠草原人工中间锦鸡儿(Caragana intermedia)为研究对象,利用2016-2017年监测获取的26次降雨事件,对比分析了两组灌丛(自然组和人工组)的冠层截留特征。结果表明:(1)试验期间共观测到有效降雨33次,总降雨量为251 mm,次平均降雨量和降雨强度分别为7.6 mm和1.14 mm/h,以雨量<2 mm,雨强<1 mm/h和降雨历时2-5 h的降雨出现次数最多;(2)自然组和人工组中间锦鸡儿平均截留量分别为1.11 mm和0.72 mm,平均截留率分别为24.81%和15.95%,两组灌丛截留存在极显著差异(P < 0.01);(3)在雨量级>15 mm时,自然组(4.57%,CV=73.38%)和人工组(5.25%,CV=51.96%)平均截留率变异性相差最大;(4)自然组和人工组截留量与降雨量,降雨历时和降雨强度之间的关系可以用幂函数描述,截留率与三者的关系均用指数函数描述较好。在降雨特征相同的情况下,灌丛形态特征是影响中间锦鸡儿冠层截留的关键因素。 相似文献
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快速城市化驱动的不透水面比例增加是引起流域洪峰和径流总量增加的直接原因,海绵城市建设通过生态基础设施网络构建增加流域透水面比例,是重构流域生态水文过程的重要途径。但是海绵城市建设在流域海绵体生态水文过程中发挥的作用尚不清楚。以深圳市布吉河流域洪湖片区为例,通过雨季水文过程要素在线连续监测来确定海绵城市建设是否改善洪湖片区生态水文过程。结果表明,中观尺度上,雨季降雨量对洪湖片区地表径流总量无直接影响,降雨强度显著影响洪湖片区地表径流峰值流量(P<0.05),日降雨量对布吉河水质影响极显著(P<0.01)。洪湖片区通过28.3%(0.85 km2)海绵面积建设,透水面比例提升,以生物滞留设施和透水铺装等强化片区蒸散和下渗过程,减少雨季径流97.2%(248.72万m3),削减典型降雨峰值流量98.2%以上,降低易涝点积水水位至7.8 cm以下,2.8%形成河川径流(布吉河),海绵面积(比例)和地表径流量削减无直接量化关系。洪湖片区污染物截留时空随保水能力得到提升,控制排放悬浮物月均浓度均低于15.60 mg/L,污染物通过径流裹挟进入... 相似文献