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921.
Multifunctional smart windows are successfully fabricated by assembling inkjet printed CeO2/TiO2 and WO3/poly(3,4‐ethylenedioxythiophene)‐poly(styrene sulfonate) films as the anode and cathode, respectively. Large optical modulation (more than 70% at 633 nm), fast switching (12.7/15.8 s), high coloration efficiency (108.9 cm2 C?1), and excellent bistability are achieved by the assembled smart windows. The multifunctional smart window not only can be used as typical electrochromic window, which can change its color to dynamically control the solar radiation transmittance through windows or protect privacy during the day, but also can be used as energy‐storage device simultaneously. The designed smart window releases the stored energy to light the bulbs and power other electronic devices at night while its color gradually reverts to transparent state. Moreover, the level of stored energy can be monitored via the visually detectable reversible color variation of the window. The fascinating multifunctional smart windows exhibit promising features for a wide range of applications in buildings, airplanes, automobiles, etc.  相似文献   
922.
芽胞杯是地钱属特有的无性繁殖器官,关于其冬季形态特征及繁殖传播的行为研究较少。现以贵州喀斯特山区常见的粗裂地钱风兜亚种(Marchantia paleacea subsp.diptera)为代表,在最冷的冬季1月份,对其芽胞杯、杯内芽胞产量及传播方式进行野外定点观察和采样分析。结果显示:(1)冬季芽胞杯形态多样。根据其颜色和杯内芽胞特点将其划分为4个生长时期:未成熟期(透明)、成熟期(绿色)、衰退期(紫色)和衰亡期(紫黑色),反映了冬季芽胞杯生长发育的不同阶段。(2)各生长时期的芽胞杯数量不同,表现出有序的凋亡特征。在统计的708个芽胞杯中,4个时期芽胞杯数量分别为62、209、254和183个,且不同时期的芽胞杯内芽胞的平均产量明显不同,不同时期单杯芽胞的平均产量分别为42、131、87和0 个;(3)冬季芽胞杯及芽胞在配子体上的密度较高,每平方米分别达到10 139和754 889个;(4)除春夏季常见的被雨滴敲打传播外,通过重力作用传播是冬季芽胞的一种重要传播方式。冬季粗裂地钱风兜亚种配子体上的芽胞杯处在不同的生长时期,形成的芽胞仍十分丰富,这对该物种适应喀斯特山区最冷月严苛环境条件具有积极的意义。  相似文献   
923.
The choice of the best sampling strategy to capture mean values of functional traits for a species/population, while maintaining information about traits’ variability and minimizing the sampling size and effort, is an open issue in functional trait ecology. Intraspecific variability (ITV) of functional traits strongly influences sampling size and effort. However, while adequate information is available about intraspecific variability between individuals (ITVBI) and among populations (ITVPOP), relatively few studies have analyzed intraspecific variability within individuals (ITVWI). Here, we provide an analysis of ITVWI of two foliar traits, namely specific leaf area (SLA) and osmotic potential (π), in a population of Quercus ilex L. We assessed the baseline ITVWI level of variation between the two traits and provided the minimum and optimal sampling size in order to take into account ITVWI, comparing sampling optimization outputs with those previously proposed in the literature. Different factors accounted for different amount of variance of the two traits. SLA variance was mostly spread within individuals (43.4% of the total variance), while π variance was mainly spread between individuals (43.2%). Strategies that did not account for all the canopy strata produced mean values not representative of the sampled population. The minimum size to adequately capture the studied functional traits corresponded to 5 leaves taken randomly from 5 individuals, while the most accurate and feasible sampling size was 4 leaves taken randomly from 10 individuals. We demonstrate that the spatial structure of the canopy could significantly affect traits variability. Moreover, different strategies for different traits could be implemented during sampling surveys. We partially confirm sampling sizes previously proposed in the recent literature and encourage future analysis involving different traits.  相似文献   
924.
Evaluating impacts to biodiversity requires ecologically informed comparisons over sufficient time spans. The vulnerability of coastal ecosystems to anthropogenic and climate change‐related impacts makes them potentially valuable indicators of biodiversity change. To evaluate multidecadal change in biodiversity, we compared results from intertidal surveys of 13 sandy beaches conducted in the 1970s and 2009–11 along 500 km of coast (California, USA). Using a novel extrapolation approach to adjust species richness for sampling effort allowed us to address data gaps and has promise for application to other data‐limited biodiversity comparisons. Long‐term changes in species richness varied in direction and magnitude among beaches and with human impacts but showed no regional patterns. Observed long‐term changes in richness differed markedly among functional groups of intertidal invertebrates. At the majority (77%) of beaches, changes in richness were most evident for wrack‐associated invertebrates suggesting they have disproportionate vulnerability to impacts. Reduced diversity of this group was consistent with long‐term habitat loss from erosion and sea level rise at one beach. Wrack‐associated species richness declined over time at impacted beaches (beach fill and grooming), despite observed increases in overall intertidal richness. In contrast richness of these taxa increased at more than half (53%) of the beaches including two beaches recovering from decades of off‐road vehicle impacts. Over more than three decades, our results suggest that local scale processes exerted a stronger influence on intertidal biodiversity on beaches than regional processes and highlight the role of human impacts for local spatial scales. Our results illustrate how comparisons of overall biodiversity may mask ecologically important changes and stress the value of evaluating biodiversity change in the context of functional groups. The long‐term loss of wrack‐associated species, a key component of sandy beach ecosystems, documented here represents a significant threat to the biodiversity and function of coastal ecosystems.  相似文献   
925.
We aimed to introduce and test the “seed mass–distribution range trade‐off” hypothesis, that is, that range size is negatively related to seed mass due to the generally better dispersal ability of smaller seeds. Studying the effects of environmental factors on the seed mass and range size of species, we also aimed to identify habitats where species may be at risk and need extra conservation effort to avoid local extinctions. We collected data for seed mass, global range size, and indicators for environmental factors of the habitat for 1,600 species of the Pannonian Ecoregion (Central Europe) from the literature. We tested the relationship between species’ seed mass, range size, and indicator values for soil moisture, light intensity, and nutrient supply. We found that seed mass is negatively correlated with range size; thus, a seed mass–distribution range trade‐off was validated based on the studied large species pool. We found increasing seed mass with decreasing light intensity and increasing nutrient availability, but decreasing seed mass with increasing soil moisture. Range size increased with increasing soil moisture and nutrient supply, but decreased with increasing light intensity. Our results supported the hypothesis that there is a trade‐off between seed mass and distribution range. We found that species of habitats characterized by low soil moisture and nutrient values but high light intensity values have small range size. This emphasizes that species of dry, infertile habitats, such as dry grasslands, could be more vulnerable to habitat fragmentation or degradation than species of wet and fertile habitats. The remarkably high number of species and the use of global distribution range in our study support our understanding of global biogeographic processes and patterns that are essential in defining conservation priorities.  相似文献   
926.
按空间代替时间序列的方法,对贵州省修文县小山坝岩溶型铝土矿区尾矿堆5个不同自然演替阶段苔藓植物多样性进行了研究。结果显示:(1)苔藓植物共有11科18属31种,其中藓类9科16属29种,苔类2科2属2种。在演替过程中,苔藓植物生活型单一,仅矮丛集型(占67.7%)和交织型(占32.3%),矮丛集型占优势地位。苔藓植物物种组成简单,纯群落较多,混合群落随演替阶段逐渐增多。(2)不同自然演替阶段苔藓植物群落Shannon-Wiener指数、Pielou均匀度指数和丰富度指数有所不同,裸岩阶段最低(0.196、0.283和-1.930),草灌丛阶段最高(3.470、1.281和2.342),乔灌木阶段逐渐下降(2.128、0.887和1.267)。苔藓植物种的替代速率与相似性变化趋势相反。小山坝岩溶型铝土矿区尾矿堆苔藓植物多样性在5个不同自然演替阶段呈先上升后下降的变化规律,多样性水平总体呈上升趋势,研究结果可为岩溶型铝土矿区生态恢复和生物多样性保护提供基础资料。  相似文献   
927.
黄檗(Phellodendron amurense Rupr.)为我国二级重点保护野生植物,在北京地区黄檗多散生于阔叶林中,数量稀少。为了解北京地区黄檗分布与环境因子的关系,促进种群扩繁,在北京百花山、松山和雾灵山自然保护区共设置了12个20 m×20 m的样地,利用CCA分析方法对不同地点黄檗的生长分布状况与海拔、坡度、坡向、郁闭度、土壤pH值、碱解氮和土壤有机质等11个环境因子的关系进行了分析。结果显示,CCA排序第一轴主要反映了海拔、郁闭度和坡度的变化,第二轴主要反映了有机质含量、碱解氮含量、pH值和坡向的变化,其中海拔、碱解氮和土壤有机质是影响黄檗生长分布的重要环境因子,低海拔、低碱解氮含量以及土壤有机质高的地段适宜黄檗分布。对影响黄檗分布的环境因子进行定量分离,结果发现环境因子对黄檗样地物种分布的解释能力为84.5%,显示出较好的排序效果,黄檗分布点受人为干扰较少,其所在植物群落与环境保持了良好的对应关系;环境因子与物种分布呈显著相关(P=0.03),表明CCA排序结果可以解释环境因子对物种分布的影响程度。  相似文献   
928.
The use of plant functional traits has become increasingly popular in ecological studies because plant functional traits help to understand key ecological processes in plant species and communities. This also includes changes in diversity, inter‐ and intraspecific interactions, and relationships of species at different spatiotemporal scales. Leaf traits are among the most important traits as they describe key dimensions of a plant's life history strategy. Further, leaf area is a key parameter with relevance for other traits such as specific leaf area, which in turn correlates with leaf chemical composition, photosynthetic rate, leaf longevity, and carbon investment. Measuring leaf area usually involves the use of scanners and commercial software and can be difficult under field conditions. We present Leaf‐IT, a new smartphone application for measuring leaf area and other trait‐related areas. Leaf‐IT is free, designed for scientific purposes, and runs on Android 4 or higher. We tested the precision and accuracy using objects with standardized area and compared the area measurements of real leaves with the well‐established, commercial software WinFOLIA using the Altman–Bland method. Area measurements of standardized objects show that Leaf‐IT measures area with high accuracy and precision. Area measurements with Leaf‐IT of real leaves are comparable to those of WinFOLIA. Leaf‐IT is an easy‐to‐use application running on a wide range of smartphones. That increases the portability and use of Leaf‐IT and makes it possible to measure leaf area under field conditions typical for remote locations. Its high accuracy and precision are similar to WinFOLIA. Currently, its main limitation is margin detection of damaged leaves or complex leaf morphologies.  相似文献   
929.
2011年12月至2012年9月, 在湘中丘陵区杉木(Cunninghamia lanceolata)人工林、马尾松(Pinus massoniana)-石栎(Lithocarpus glaber)针阔混交林、南酸枣(Choerospondias axillaries)落叶阔叶林、石栎(Lithocarpus glaber)-青冈(Cyclobalanopsis glauca)常绿阔叶林1 hm2的长期定位观测样地, 采集0-15 cm、15-30 cm土层土壤样品, 测定土壤微生物生物量碳(MBC)、可矿化有机碳(MOC)、易氧化有机碳(ROC)、水溶性有机碳(DOC)含量, 分析4种森林土壤MBC、MOC、ROC、DOC含量的季节变化特征, 为揭示天然林保护与恢复对土壤有机碳(SOC)库的影响机理过程提供基础数据。结果表明: 森林土壤MBC、MOC、ROC、DOC含量具有明显的季节动态, 且不同森林同一土壤活性有机碳组分的季节变化节律基本一致, MBC、MOC、ROC含量表现为夏、秋季较高, 春、冬季较低; DOC含量表现为春、夏、冬季较高, 秋季最低; 同一森林不同土壤活性有机碳组分含量的季节变化节律不同; 土壤MBC、MOC、ROC、DOC含量与土壤自然含水率、SOC、全N、水解N、全P (除杉木人工林土壤MBC、MOC、ROC外)、速效P含量显著或极显著正相关, 与土壤pH值、全K、速效K含量相关性不显著, 表明不同森林类型外源碳库投入和土壤理化性质的差异是导致不同森林类型土壤活性有机碳含量差异显著的主要原因, 该区域森林土壤活性有机碳各组分含量的季节变化与各森林类型组成树种生长节律及其土壤水分含量和SOC、N、P的可利用性, 以及土壤活性有机碳各组分的来源有关, 森林土壤MBC、MOC、ROC、DOC含量可作为衡量森林土壤C、N、P动态变化的敏感性指标。  相似文献   
930.
叶大小-叶脉密度的权衡关系是植物叶经济谱理论的基础, 对理解资源竞争条件下植物叶片的物理构建与生理代谢的关系具有重要的意义。该文采用标准化主轴估计(standardized major axis estimation, SMA)的方法, 按芨芨草(Achnatherum splendens)株丛密度设置I (>12丛·m-2)、II (8-12丛·m-2)、III (4-8丛·m-2)和IV (<4丛·m-2) 4个密度梯度, 以叶面积和叶干质量分别表示叶大小, 对张掖洪泛平原湿地不同密度条件下芨芨草种群的叶大小和叶脉密度的关系进行研究。结果表明: 随着芨芨草株丛密度的降低, 湿地群落的土壤含水量逐渐减小、土壤电导率逐渐增加, 芨芨草的净光合速率(Pn)、蒸腾速率(Tr)和分枝数呈先增大后减小的趋势, 叶面积、叶干质量、比叶面积和株高呈逐渐减小趋势、光合有效辐射(PAR)和叶脉密度呈逐渐增加趋势; 芨芨草叶大小和叶脉密度在高密度(I)和低密度(IV)样地均呈极显著负相关关系(p < 0.01), 中密度(II、III)样地二者呈显著负相关关系(p < 0.05); 叶大小和叶脉密度回归方程的SMA斜率在不同密度样地均显著小于-1 (p < 0.05), 即芨芨草叶大小和叶脉密度呈“此消彼长”的权衡关系。在高密度湿地群落芨芨草倾向于大叶片低叶脉密度的叶片构建模式, 在低密度湿地群落选择小叶片高叶脉密度的异速生长模式, 体现了密度制约下湿地植物的生物量分配格局和资源利用对策。  相似文献   
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