能源甘蔗不同叶位叶片形态、光合气体交换及其与产量关系

利用CI-203叶面积分析仪和CI-301CO2气体分析仪分析4个能源甘蔗品种分蘖期和伸长初期不同叶位层叶片的形态特征和光合气体交换特征参数.结果表明,不同基因型不同叶位层间叶片形态、光合气体交换特征参数存在显著差异.分蘖期和伸长初期蔗叶的叶长、叶宽、叶面积、长宽比等叶片形态参数和净光合速率、蒸腾速率、气孔导度和水分利用率等光合气体交换特征参数均表现为随着叶位的下降,自上而下逐渐变小.逐步回归分析结果表明,分蘖期第3叶的叶宽和水分利用率及第5叶的叶宽对产量形成影响较大;而伸长初期第1叶和第3叶的叶面积对产量形成影响较大.图8表4参15     

增强的UV—B辐射对黄瓜（Cucumis sativus）不同叶位叶片生长、光合作用和呼吸作用的影响

在植物生长室中，黄瓜植株第1片真叶出现后，用人工UV－B光源照射60d，测定植物各叶位叶片的生长和生理活动。结果表明，UV－B辐射条件下，植物出叶时间被延迟，叶面积和叶干重下降，降幅与叶位高低正相关；叶片含水量降低，老龄叶片（1叶，下位叶）和幼龄叶片（第5叶，上位叶）的水分降幅均高于成年叶片（第3叶，中位叶）；叶片的伸展速度，叶片数目以及单叶面积减少,致使黄瓜总叶面积下降；植株节间长度缩短,是植株矮化的重要原因；根、茎、叶等器官之间的相关生长变化不大，叶片生长在其中起重要的协调作用。UV－B降低Pn和EAQE，对光合的抑制程度随叶位升高而增加，UV－B辐射后，黄瓜叶片的光呼吸显著提高，增幅与叶片发育阶段有关，UV－B对黄瓜第1叶的暗呼吸没有影响，第2、3叶略微下降，第4叶显著升高，分析认为，植株矮化叶面积减少有利于植物适应UV－B辐射；水分含量和光合作用减少、呼吸作用增强是黄瓜生长受抑制的生理基础。图2表2参18     

南亚热带常绿阔叶林林冠层附生植物及其宿主叶片的形态解剖特征

选择南亚热带常绿阔叶林中具有代表性的4种林冠层附生植物：白背瓜馥木（Fissistigma glaucescens）、瓜子金（Dischidia chinensis）、蔓九节（Psychotria serpens）、山蒌（Piper hancei）及其主要宿主植物：厚壳桂（Cryptocaryachinensis）、荷木（Schimasuperba）、华润楠（Machilus chinensis）、锥栗（Castanopsis chinensis）为研究对象,对其叶片形态结构和解剖结构特征进行比较。研究结果表明：宿主植物与附生植物的叶片形态结构差异显著。相对于4种宿主植物,4种附生植物叶片无蜡被,比叶面积大,且具有含水量高,上下表皮厚度增加,气孔密度、气孔面积减少等特征,有利于叶片对水分和养分的吸收、贮存和利用。着生在林冠层不同部位的附生植物的叶片形态结构特征随着光合有效辐射、温度、湿度等微环境因子的变化表现出显著的差异：位于冠层顶部的瓜子金和蔓九节叶片小而厚,含水量高,气孔密度低且覆盖角质膜,更适应冠层顶部高温、低湿、高光照的环境;位于冠层下部的白背瓜馥木和山蒌叶片相对较薄,气孔面积较大,叶肉细胞分化明显,海绵组织排列松散,更适应冠层中下部低温、高湿、弱光照环境。变化的叶片结构是植物适应环境条件的重要表现。     

喀斯特地区白三叶形态和遗传多样性研究

白三叶（Trifolium repens）的形态学特征随利用年限的增加而进化,单株叶数、生长点数、中叶长、中叶长宽比以及种群内个体之间变异性随着年限的增加而增加,而叶层高度、中叶宽则下降。三个不同年龄草地的平均单株叶质量、根质量、地上生物量、地上生物量与地下生物量的比值等指标数值接近,差异不显著。但是,与茎有关的指标如茎质量等差异显著,匍匐茎生物量随年限的增加而增加,以回避动物采食等干扰,并有利于占据动态空斑而增加种群的持久性。100年白三叶的等位基因数没有20年的高,意味着年限越长的种群以少数大克隆体占优势。     

上海人工绿地群落UVB屏蔽效应与冠层特征的关系

由于大气污染等人为因素,到达地面的紫外辐射逐年增强,而绿地作为城市居民的重要休憩场所,营造健康的绿地辐射环境至关重要.通过研究上海人工绿地典型群落内UVB辐射的日进程,并以全光照旷地为对照分析比较群落UVB屏蔽效率,采用欧氏距离聚类分析方法,对群落UVB屏蔽效率和群落叶面积指数、枝下高等冠层特征因子的相关关系进行分析并总结影响屏蔽效率的群落结构因子,以期为营造健康的绿地休憩环境提供借鉴和参考.2007年7月6-8日期间对上海植物园8种类型群落和旷地2 m高处UVB辐射进行同步观测.对观测数据分析表明:1)所测定人工群落UVB平均屏蔽效率为91.1%,群落内2m高处UVB辐射通量仅为全光照旷地的14%.毛竹群落和女贞群落屏蔽效率最高,分别为98.5%,97.8%.2)不同植物群落UVB屏蔽效率在冠层特征梯度上表现出显著的分异,植物群落内UVB辐射通量与群落叶而积指数成显著负相关关系,与群落高度和枝下高呈显著正相关关系.3)在植被覆盖较少且紫外辐射地面反射较为强烈的游憩场所,可考虑种植叶倾角较小且叶面积较大的植物,如女贞(Ligustrum lucidum)、丹桂(Osmanthus fragrans)等.     

若尔盖典型高寒湿地植物叶功能性状对水深梯度的响应

高寒泥炭沼泽湿地储存着大量有机碳，影响全球碳库的收支平衡，作为重要的生态因子，植物功能性状显著影响着生态系统的碳输入与输出过程.为了解水位变化对高原高寒湿地植物功能性状的影响并深入理解水位下降下的高寒泥炭沼泽碳循环，以青藏高原东部若尔盖典型沼泽湿地两种优势植物——木里苔草(Carex muliensis；湿生植物，即喜欢潮湿环境而不能忍受长时间水位不足的陆生植物)和斑唇马先蒿(Pedicularis longiflora var.tubiformis；中生植物，即介于湿生与旱生植物之间而不能忍受严重干旱或长期水涝的植物)为研究对象，采用“中宇宙”水位模拟试验，分析两种植物在10 cm(D₁₀)、0 cm(D₀)、–20 cm(D_-20)和–50 cm(D_-50)水位梯度下叶形态性状的差异，以及叶片光合气体交换参数、叶绿素荧光参数等的变化规律.结果表明：(1)木里苔草通过减小叶长、叶面积、比叶面积、叶干重和增加叶厚以适应水位下降，斑唇马先蒿则通过减小叶长、叶宽、叶面积、比叶面积和叶干重来适应水位上升....     

区域尺度上麻栎叶片性状对环境因子的响应规律

叶片性状反映了植物对环境的适应能力及其自我调控能力。区域尺度上单一物种叶片功能和形态性状的变化规律尚存在争议。以25个麻栎(Quercus acutissima)天然林种群为对象,采用野外调查和室内实验相结合的方法,分析了区域尺度上比叶面积(SLA),单位叶重的氮质量分数(Nmass)、磷质量分数(Pmass)、叶氮磷比(N∶P),单位叶面积的氮质量分数(N_(area))、磷质量分数(Parea)等功能性状和叶片面积(LA)、周长(LP)、叶长度(LL)、叶宽度(LW)、叶片长宽比(L∶W)等形态性状的变化。结果表明,(1)麻栎叶片面积变化范围为28.53~59.41 cm~2;周长为31.21~47.54 cm;叶长为11.72~17.25cm;叶宽为3.41~5.46 cm;叶长宽比为2.79~3.75;比叶面积为77.38~152.71 cm~2·g~(-1);Nmass为17.90~26.20 mg·g~(-1);Pmass为0.68~1.61mg·g~(-1);N_(area)为1.42~2.63 mg·cm~(-2);Parea为0.07~0.13 mg·cm~(-2);N∶P为14.01~28.80。(2)随着海拔的增加,麻栎比叶面积、Nmass及叶宽均呈先下降后上升的二次曲线变化趋势(P0.05),而N_(area)则呈先上升后下降的二次曲线变化趋势(P0.05)。(3)麻栎叶片面积和长度随等效纬度的增加均呈先上升后下降的二次曲线变化趋势(P0.05)。(4)麻栎叶片面积、长度及宽度随年均温度的升高均呈先上升后下降的二次曲线变化趋势(P0.05)。(5)随着年均降水量的增加,麻栎叶长度呈先上升后下降的趋势(P0.05),而叶片面积与其呈显著正相关(P0.05)。叶片功能性状主要受海拔引起的水热变化的影响,而叶片形态性状则主要受到海拔、纬度及气象因子综合作用的影响。研究结果有助于揭示区域尺度上植物叶性状的变化规律及其环境机制,为预测植物性状在未来环境下的变化及适应奠定基础。     

UV-B辐射增强对紫茎泽兰和艾草生长形态及竞争效应的影响

为了解外来入侵植物紫茎泽兰(Eupatorium adenophorum L.)与本地土著植物艾草(Artemisia argyi Levl)在UV-B辐射增强条件下生长形态和竞争关系的变化,以这两种植物为试验材料,以自然光为对照进行5周UV-B辐射增强实验和2周恢复实验,并测定和分析植株形态指标(株高、叶片鲜重、叶长、叶宽和叶面积)、叶片解剖结构(上下表皮、栅栏组织和海绵组织)和竞争能力指标(株高、叶生物量和茎生物量).结果显示:艾草叶片鲜重和叶面积在辐射前两周显著减小(P0.05)和极显著减小(P0.01),株高没有差异,而紫茎泽兰的株高、叶鲜重和叶面积在辐射期间都明显减小,且恢复实验时仍差异显著.艾草叶片厚度在UV-B辐射下极显著增大(上表皮、栅栏组织和海绵组织极显著增大),紫茎泽兰叶片变厚但不明显,恢复实验时显著减小,叶片解剖结构表明UV-B辐射使两类杂草叶片细胞间隙变大.UV-B辐射对紫茎泽兰生物量的抑制比较显著,对艾草生物量的抑制在混种时显著;在UV-B辐射下,紫茎泽兰和艾草的相对生物量分别为1.03和0.81,在自然状态下分别为0.91和0.97,两者的相对生物量总和不变,为0.94.本研究表明艾草对UV-B辐射的形态抗性较强,UV-B辐射刺激了紫茎泽兰的种内竞争,也降低了艾草的种间竞争能力,但无论在自然条件下还是UV-B辐射增强条件下艾草的种间竞争能力都比紫茎泽兰强,但不足以淘汰对方.     

20个小麦品种对UV-B辐射增强响应的形态学差异

研究了大田栽培和自然光条件下 ,模拟UV -B辐射增强对 2 0个小麦品种影响的形态学差异。结果表明 ,叶面积指数、株高、节间长、茎基粗对UV -B辐射增强响应具有品种间差异。株高和节间长对UV -B辐射响应具有一致性 ,呈极显著正相关。根据形态响应指数 (MRI) ,耐性品种 (MRI>- 8 5 )为 :辽春 9>文麦 3>大理 90 5 >兰州 80 10 1>绵阳 2 6 >YV 97- 31>毕 90 - 5。敏感品种 (MRI <- 49 4)为 :会宁 18>繁 19>楚雄 880 7>My 94- 9>黔 14>云麦 39>陇春 16。耐性品种具有较小的叶展开角度 ,敏感品种具有较大的叶展开角度。UV -B辐射还不同程度抑制小麦条锈病的发生     

攀援角度对五爪金龙形态、生物量分配及相对生长速率的影响

对不同攀援角度五爪金龙的形态、生物量分配及生长特性等参数进行了分析.结果表明:随攀援角度的增加,五爪金龙主茎长度增加、总叶面积减少;其根生物量比(RMR)增加,叶生物量比(LMR)下降,茎生物量比(SMR)变化不明显.其中,0°攀援生长五爪金龙的叶生物量比是根生物量比的4.625倍;90°攀援生长五爪金龙的根、茎和叶的生物量分配差异最小,在0.318~0.363 g·g-1之间.攀援生长五爪金龙(30°~90°)的相对生长速率随攀援角度的增加而增大.对比0°和90°,30°和60°攀援生长五爪金龙的形态、生物量分配和生长参数均表现出较高的可塑性,对不同倾角支持物的适应能力很强.0°和90°攀援生长五爪金龙的叶面积指数(LAI)、相对生长速率(RGR)和净同化速率(NAR)均高于30°和60°.攀援角度对五爪金龙的形态、生物量分配及相对生长速率存在不同程度的影响,较高相对生长速率的五爪金龙具有较强的种间竞争能力和入侵性.     

Modeling cotton (Gossypium spp.) leaves and canopy using computer aided geometric design (CAGD)

The research presented here develops a geometrically accurate model of cotton crop canopies that can be used to explore changes in canopy microenvironment and physiological function with leaf structure. We develop an accurate representation of the leaves, including changes in three-dimensional folding and orientation with age and cultivar. Photogrammetrical analysis of leaf surfaces is used to generate measured points at known positions. Interpolation of points located on the surface of the cotton leaves is then performed with a tensor product interpolants model that generates a generic leaf shape. Dynamic changes in leaf shape and canopy position over the growing season are based on measurements of cotton canopies in the field, and are used to modulate the generic leaf shape. The simulated leaves populate a canopy element based on statistical distributions from measured crop canopies. The simulation is found to give a good representation of cotton canopy leaves, adequately capturing the three-dimensional structure of the leaves and changes in leaf shape and size over the growing season. The simulated canopy accurately estimates leaf area index, except for the earliest measurement period prior to canopy closure. The application of the CAGD algorithm for representing cotton leaf and canopy geometry, and the technique for changing the leaves’ spatial position, size and shape through time of four representative cotton canopies is found to be a useful tool for developing a realistic crop canopy. We use leaf area index (LAI) as a measure of the accuracy of model-predicted LAI values in comparison to LAI in crop canopies in situ, obtaining r² values ranging from 0.82 to 0.92. The level of detail captured in the model could contribute greatly to future studies of physiological function and biophysical dynamics within a crop canopy.     

Modelling radiative balance in a row-crop canopy: Row-soil surface net radiation partition

Row crops like vineyards undergo various and significant manipulations of training system and cultural practices, which strongly influence the quality of products. Variations of water vapour fluxes from the soil surface and the leaves in the row volume are closely linked to the ratio of energy available to each compartment. A physically realistic model of available energy partition between the rows and the soil surface is therefore a key factor towards optimization of such systems, and must be included in canopy models. A number of available models were not directly validated. The purpose of the study was therefore to design a model of net radiation partition and check it directly.The model of net radiation partition between rows (Rnv), considered as a whole, and intervening soil surface (Rns) of a row-crop canopy was developed from physically realistic yet simple assumptions:

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global solar (short wave) radiation partition was calculated by a previously validated geometric model;

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long-wave radiative fluxes between the soil surface, the rows and the atmosphere were calculated from the corresponding view factors, which only depended on canopy geometry;

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atmospheric radiation was estimated by a simple empirical relation based on air temperature as the only input variable;

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air temperature in the vicinity of leaves replaced leaf surface temperatures as a more convenient input variable, with little loss of information.

The input variables were incoming direct and diffuse solar radiation, soil surface mean temperature and air temperature near the leaves. The main parameters were soil and leaf albedos, row porosity and dimensions.A direct validation of the model was attempted by measuring net radiation above the canopy and at five positions above the soil surface in a vineyard of the Bordeaux area. The reliability of soil surface net radiation measurements was estimated by thorough error propagation analysis. When found significant, errors were corrected and finally soil surface net radiation data were corrected only for delay in direct downward solar radiation striking net radiometers, because canopy was discontinuous and height of net radiometers was not negligible compared to canopy height.In these conditions, model calculations were in agreement with measurements, although the model slightly underestimated Rns and therefore overestimated Rnv. As the mean error was about 20 W m⁻², and therefore compatible with instrument accuracy, the results were considered satisfactory.This available energy partition model is able to estimate radiative balance in various canopy systems and in various thermal environment conditions, leading to easier simulations of energy balance and water fluxes. It could therefore be a useful tool for optimizing row-crop canopies, taking fully into account any kind of present or future thermal environment.     

Modelling radiative balance in a row-crop canopy: Cross-row distribution of net radiation at the soil surface and energy available to clusters in a vineyard

Distribution of energy at the soil surface in a row-crop influences mainly soil temperature and water content, and therefore root activity, nitrogen mineralization and within canopy air temperature, which all affect plant physiology. In the case of a vineyard, it is also closely related to the energy available to the berries and therefore most influential for fruit quality. The aim of this study was to develop a simplified model of available energy distribution at the soil surface and at the bottom of the rows, where most of the clusters are located. Such a model would be helpful for optimising some aspects of row-crop management like training system choice, row geometry, leaf area density, and soil surface maintenance practices.The model simulated radiation balance at the soil surface, split up into downward and upward short- and long-wave fluxes. Row shadows were calculated at any point of the inter-row space, in interaction with actual row geometry and simplified porosity distribution within row volume. All hemispheric radiations (long-wave and diffuse solar radiation) were calculated according to view factors between the row and soil surfaces. Input variables were therefore incoming solar radiation over the canopy, air temperatures near the row walls and soil surface temperatures. Parameters were row geometry, dimensions and porosities.The model was validated in a 7 years old Merlot vineyard in the Médoc area, by comparing model predictions to measured net radiation (Rns) at five positions above the inter-row soil surface. Along the row sampling was achieved by a moving device carrying the net-radiometers. Structure of the vegetation was kept constant during the experiment and gap fraction parameters were derived from pictures of shadows at the soil surface. Since Rns measurements are impracticable directly at the soil surface and horizontal distribution of Rns is heterogeneous, comparison was performed by calculating net radiation at the actual measurement height which was close to average cluster height.Model prediction agreed with field measurement in most conditions, which suggests that all short- and long-wave radiation fluxes, as well as interactions with the canopy structure, were well described. Rns, energy available to clusters, and soil surface temperature variations were all mainly driven by shading due to the rows. Coupling the model to soil heat transfer and convective fluxes to the atmosphere models will help forecasting soil temperature distribution at the surface and in depth as well as canopy microclimate. The model will also be an essential part of a more elaborate model of cluster microclimate, a key determinant of berry quality.     

不同底质和透明度下马来眼子菜的表型可塑性研究

马来眼子菜(Potamogeton malaianusMiq.)是目前太湖沉水植物优势种之一。文章比较分析了3种不同底质和透明度情况下马来眼子菜的生长特征,探索其在太湖不断扩展的原因及其适应性。分别选取粘土质粉砂、粉砂和下蜀黄土底质上生长的马来眼子菜进行观察试验。结果表明,这3种底质在粒度组成、营养盐和分布特征上具有显著差异。在太湖粘土质粉砂和粉砂底质上马来眼子菜的生物量比下蜀黄土底质上的马来眼子菜高,其生物量随着底质营养盐的增加而增加。马来眼子菜与觅光相关的形态指标,如高度、节间距、节数、叶数、叶长及叶面积均随着底质营养盐的增加而显著增加。马来眼子菜的冠层高度与水体的透明度呈显著负相关,表明其对剧烈变化的湖泊光环境具有很强的适应能力。马来眼子菜在不同底质上的形态可塑性是其优先占据湖泊资源成为优势种的重要原因。     

The role of canopy structural complexity in wood net primary production of a maturing northern deciduous forest

The even-aged northern hardwood forests of the Upper Great Lakes Region are undergoing an ecological transition during which structural and biotic complexity is increasing. Early-successional aspen (Populus spp.) and birch (Betula papyrifera) are senescing at an accelerating rate and are being replaced by middle-successional species including northern red oak (Quercus rubra), red maple (Acer rubrum), and white pine (Pinus strobus). Canopy structural complexity may increase due to forest age, canopy disturbances, and changing species diversity. More structurally complex canopies may enhance carbon (C) sequestration in old forests. We hypothesize that these biotic and structural alterations will result in increased structural complexity of the maturing canopy with implications for forest C uptake. At the University of Michigan Biological Station (UMBS), we combined a decade of observations of net primary productivity (NPP), leaf area index (LAI), site index, canopy tree-species diversity, and stand age with canopy structure measurements made with portable canopy lidar (PCL) in 30 forested plots. We then evaluated the relative impact of stand characteristics on productivity through succession using data collected over a nine-year period. We found that effects of canopy structural complexity on wood NPP (NPPw) were similar in magnitude to the effects of total leaf area and site quality. Furthermore, our results suggest that the effect of stand age on NPPw is mediated primarily through its effect on canopy structural complexity. Stand-level diversity of canopy-tree species was not significantly related to either canopy structure or NPPw. We conclude that increasing canopy structural complexity provides a mechanism for the potential maintenance of productivity in aging forests.     

Light-stress avoidance mechanisms in a Sphagnum-dominated wet coastal Arctic tundra ecosystem in Alaska

The Arctic experiences a high-radiation environment in the summer with 24-hour daylight for more than two months. Damage to plants and ecosystem metabolism can be muted by overcast conditions common in much of the Arctic. However, with climate change, extreme dry years and clearer skies could lead to the risk of increased photoxidation and photoinhibition in Arctic primary producers. Mosses, which often exceed the NPP of vascular plants in Arctic areas, are often understudied. As a result, the effect of specific environmental factors, including light, on these growth forms is poorly understood. Here, we investigated net ecosystem exchange (NEE) at the ecosystem scale, net Sphagnum CO2 exchange (NSE), and photoinhibition to better understand the impact of light on carbon exchange from a moss-dominated coastal tundra ecosystem during the summer season 2006. Sphagnum photosynthesis showed photoinhibition early in the season coupled with low ecosystem NEE. However, later in the season, Sphagnum maintained a significant CO2 uptake, probably for the development of subsurface moss layers protected from strong radiation. We suggest that the compact canopy structure of Sphagnum reduces light penetration to the subsurface layers of the moss mat and thereby protects the active photosynthetic tissues from damage. This stress avoidance mechanism allowed Sphagnum to constitute a significant percentage (up to 60%) of the ecosystem net daytime CO2 uptake at the end of the growing season despite the high levels of radiation experienced.     

北京4种阔叶绿篱球的减噪效应及其影响因子

运用AWA6288型多功能声级及TmeRTA音频分析软件等仪器对北京4种常见阔叶绿篱球的减噪功能进行了测定,并对其结构特征进行了定量化统计,以探寻与植物减噪密切相关的影响因子。结果表明：小叶黄杨球（Buxus microphylla）平均相对A声级减噪能力最强,为1．76dB／m;紫叶小檗球（Berberis thunbergii cv．atropurpurea）相对最差,为1．05dB／m。紫叶小檗球与大叶黄杨球（Euonymus japonicus）、小叶黄杨球、金叶女贞球（Ligustrum vicaryi）在平均相对A声级减噪能力、减噪率方面均存在冠著差异。影响单株植物减噪排名前5的相关结构因子分别是树冠体积（0．804）、冠高（0．781）、绿篱高度（0．733）、叶质地（0．690）、平均冠宽（0．679）;叶大小、冠层、叶质地和倾斜状态、叶密度、枝密度5个主因子的累积方差贡献率已达85．233％,在绿化减噪应用中要重点考虑这5个因子。大叶黄杨球平均相对A声级减噪能力随植株大小变化没有显著变化,与树体各结构因子不相关,这可能与研究的样本量较少或者树体结构特征差异不明显有关;影响不同种类植物减噪的相关因子不尽相同。     

The Structure of the Shear Layer in Flows over Rigid and Flexible Canopies

Flume experiments were conducted with rigid and flexible model vegetation to study the structure of coherent vortices (a manifestation of the Kelvin–Helmholtz instability) and vertical transport in shallow vegetated shear flows. The vortex street in a vegetated shear layer creates a pronounced oscillation in the velocity profile, with the velocity near the top of a model canopy varying by a factor of three during vortex passage. In turn, this velocity oscillation drives the coherent waving of flexible canopies. Relative to flows over rigid vegetation, the oscillation in canopy geometry has the effect of decreasing the amount of turbulent vertical momentum transport in the shear layer. Using a waving plant to determine phase in the vortex cycle, each vortex is shown to consist of a strong sweep at its front (during which the canopy is most deflected), followed by a weak ejection at its rear (when the canopy height is at a maximum). Whereas in unobstructed mixing layers the vortices span the entire layer, they encompass only 70% of the flexibly obstructed shear layer studied here.