藏东南色季拉山林线过渡带7种灌木植物的叶氮回收潜力

在湿润的青藏高原东南部, 为什么常绿灌木广泛占据高海拔的林线过渡带及以上的高山带, 而落叶灌木只能零星分布?未来气候变暖对该区不同功能群物种的影响是否相同?通过测定西藏东南部色季拉山林线过渡带7种灌木凋落叶的氮含量, 比较了极端高海拔地区灌木不同表达单位的叶氮回收潜力在不同功能群间的差异, 以及不同海拔、不同坡向间的差异, 试图从养分限制的角度为解答上述科学问题提供基础数据。研究结果表明: 1)从基于单位质量叶氮含量(N_mass)的叶氮回收潜力来看, 常绿灌木裂毛雪山杜鹃(薄毛海绵杜鹃) (Rhododendron aganniphum var. schizopeplum)显著高于其他6种落叶灌木, 但由于受比叶重的影响, 基于单位面积叶氮含量(N_area)的叶氮回收潜力则表现为落叶灌木总体较高; 2)落叶灌木山生柳(Salix oritrepha)和拉萨小檗(Berberis hemsleyana)的叶氮回收潜力在不同海拔或不同坡向间均无显著差异, 但裂毛雪山杜鹃基于N_mass的叶氮回收潜力在高海拔地段明显偏高。在极端高海拔的林线过渡带, 通过降低凋落叶中的氮含量(增加叶氮回收潜力)以达到高效的养分利用可能是常绿灌木裂毛雪山杜鹃适应高寒胁迫环境的重要策略。与落叶灌木相比, 常绿灌木裂毛雪山杜鹃叶氮回收潜力对未来气候变暖可能更敏感。     

五大连池新期火山熔岩台地3种共有植物的叶功能性状及其相互关系

以五大连池新期火山熔岩台地13个稳定的自然植物群落共有种香杨、万年蒿、岩败酱为研究对象,测定其叶干物质含量(LDMC)、比叶面积(SLA)、叶氮含量(LNC)、叶磷含量(LPC)、叶氮磷比(N/P)等叶功能性状,研究不同生境下3种植物叶功能性状的变异特征,探讨新期火山熔岩台地植物叶功能性状相互之间的内在联系及其对环境的适应性。结果表明:(1)3种植物LDMC变化在0.294~0.359g·g~(-1)之间,SLA变化在9.082~22.347m2·kg~(-1)之间;与其他区域的研究结果相比,新期火山熔岩台地植物的LDMC值相对偏大、SLA值相对偏小,说明五大连池新期火山熔岩台地的植物采用高LDMC低SLA策略适应贫瘠恶劣的环境。(2)3种植物LNC变化在9.690~15.710g·kg~(-1)之间,LPC变化在0.669~1.078g·kg~(-1)之间,叶钾含量(LKC)变化在10.410~29.830g·kg~(-1)之间,叶N/P的变化在9.781~20.990之间;与其他区域的研究结果相比,新期火山熔岩台地植物LNC和LPC值相对偏小,LKC和N/P值相对偏大,说明五大连池新期火山熔岩台地的植物生长主要受磷素的限制,而且LNC偏小和LKC偏高与新期火山熔岩台地土壤中全N、全K的含量变化特征有关。(3)通过ANVOA分析发现,群落间植物叶功能性状的变异幅度较小,3种植物之间N/P、LDMC和SLA的变异幅度也较小,这说明在水分和养分极缺的火山熔岩台地植物对其生境的适应对策相似。(4)Pearson相关分析发现,SLA与LDMC以及N/P与LDMC和SLA均呈显著负相关关系。     

放牧干扰对荒漠草原植物叶性状及其相互关系的影响

以宁夏退化荒漠草原优势植物牛心朴子、乳浆大戟、甘草和牛枝子为对象,分析放牧干扰对植物的比叶面积(specific leaf area, SLA)、叶干物质含量(leaf dry matter content, LDMC)、叶面积和叶干质量等叶性状的影响,探讨荒漠草原生态系统中不同物种对环境改变的响应和适应对策.结果表明: 随着放牧强度的降低,牛心朴子、乳浆大戟、甘草和牛枝子的SLA总体呈显著降低的趋势;SLA在不同放牧强度间差异显著,而LDMC则无显著差异.不同植物的叶性状相关性存在差异,牛心朴子和甘草的SLA和LDMC呈显著负相关,而乳浆大戟和牛枝子的SLA和LDMC呈正相关.牛心朴子、甘草、乳浆大戟和牛枝子的SLA对生存环境改变的反应比LDMC更敏感.植物的SLA可以作为荒漠草原植物资源利用对策的指示指标.     

植物叶片性状对气候变化的响应研究进展

叶片性状反映了植物对环境的高度适应能力及其在复杂生境下的自我调控能力。叶片性状如何响应和适应气候变化是植物适应性研究的重点内容。该文系统综述了叶片大小、比叶质量、叶片氮含量、碳同位素等指标对气候变化响应的最新研究结果。不同叶片性状对气候变化的响应结果存在差异,所指示的生态学含义也有所不同。单一叶片性状不能全面地反映植物对气候变化的响应;不同尺度的研究(如环境的修饰或筛选作用的研究)还存在很多不确定性。高寒地区的研究工作相对缺乏。该文有助于理解植物与气候之间的相互关系、植物对气候变化的响应与适应对策,对了解植物演化、预测植物在未来气候变化条件下的变化特征具有一定意义。     

科尔沁沙地东南部地区主要植物叶片性状及其相互关系

选取科尔沁沙地东南部地区23种主要植物,将其划分成草本、灌木和乔木3种生长型,并分别测定其叶片鲜重(FW)、干重(DW)、叶干物质含量(DMC)、面积(AR)、比叶面积(SLA)和厚度(TH)等6项叶片性状因子。结果表明,草本植物的叶片性状比灌木和乔木变异大;平均SLA和DMC草本<灌木<乔木,DW反之,而TH则没有明显的变化。方差分析发现,除DW和TH外,SLA和DMC在不同生长型中的变化显著,并且SLA与DMC呈显著负相关,说明SLA和DMC是在植物资源利用分类轴上划分植物种类的最佳变量。对于厚度,还需进一步进行研究。     

青海省沙珠玉治沙站17种主要植物叶性因子的比较

国外大量研究结果表明,具有高叶氮含量和低比叶面积的干旱地区植物往往具有较高的水分利用效率。选取青海省沙珠玉治沙站地区17种主要植物(野生9种,人工8种) ,分别测定其比叶面积(SL A) ,单位重量叶氮含量(Nmass)及单位面积叶氮含量(Narea) ,并与贡嘎山湿润森林样带测定数据进行比较分析。结果表明,Nmass随SL A的增加而增加,但Nmass与SL A关系格局在固定沙丘野生多年生草本-灌木植物(类群1,Narea>3.0 g m- 2 )与流动沙丘野生短命草本植物(类群2 ,Narea<3.0 g m- 2 )之间存在策略位移现象,即在相同SL A下,类群1比类群2具有更高的叶氮含量,或在相同Nmass时类群1比类群2具有更小的比叶面积。在8个人工物种中,柠条锦鸡儿、中间锦鸡儿、绵柳和西北沙柳等灌木属于类群1,而甘草、小叶锦鸡儿、柽柳和青杨属于类群2 ,前者比后者具备更好的干旱适应机制,建议在生产上优先考虑前者。流动沙丘野生短命草本植物具有较低的叶氮含量和较高的比叶面积,这一特征与流动沙丘土壤贫瘠及其生长期内降水集中和土壤水分含量相对丰富密切相关。     

唐古特白刺叶功能性状沿气候梯度的变异特征

叶功能性状与植物的生长对策及资源利用效率密切相关,研究叶功能性状沿气候梯度的变异特征能为理解植物对气候变化的响应机制提供一种简便可行的测定指标。以我国西北荒漠地区广泛分布的唐古特白刺（Nitraria tangutorum）为研究对象,对其比叶面积（SLA）、单位质量和单位面积叶氮含量（N_mass、N_area）、单位质量和单位面积叶建成成本（CC_mass、CC_area）进行测定,分析这些叶功能性状及性状相关关系沿气候梯度的变异特征。结果表明,唐古特白刺叶功能性状（CC_area除外）在气候梯度下存在显著差异,其中,温度是决定唐古特白刺SLA变化的主要因子,SLA随着温度的增加而增加;降水和温度对唐古特白刺N_mass、N_area和CC_mass均有显著影响,N_mass和N_area随着降水和温度的增加而降低,而CC_mass呈增加趋势。沿气候梯度,唐古特白刺SLA-N_mass、CC_mass-N_mass和CC_area-N_area的线性正相关关系发生平移,导致在相同SLA、CC_mass和CC_area下,降水和温度较低的地区具有更高的N_mass和N_area。这一结果表明唐古特白刺能通过调节叶功能性状之间的关系来适应气候的变化,并形成性状间的最佳功能组合。     

从异龄叶性状分析几种常绿阔叶植物变异与关联

该研究从个体与物种两个水平分析福建省鬼洞山中亚热带常绿阔叶次生林中七种阔叶树种异龄叶的平均叶面积(MLA)、比叶面积(SLA)和叶干物质含量(LDMC)三个性状的变异及关联,探讨叶性状物质分配策略对植物生活策略优化的限制性影响。结果表明:(1)对七种阔叶树种的个体和物种水平变异系数而言,均为MLA(82.9%;76.9%)SLA(38.9%;35.5%)LDMC(25.4%;23.8%);在个体和物种水平上当年生叶片MLA变异系数(71.5%;64.0%)小于往年生叶片(72.2%;65.8%),SLA、LDMC值则相反。(2)在个体和物种水平,当年生叶MLA对往年生叶MLA变异的解释率分别为50.1%和61.5%,当年生叶SLA对往年生叶SLA变异的解释率分别为56.6%和77.0%,当年生叶LDMC对往年生叶LDMC变异的解释率分别为51.7%和68.3%。(3)7种亚热带常绿阔叶植物异龄叶MLA、SLA与LDMC变化规律说明,当年生叶与往年生叶投资相同干物质,当年叶可形成更大的叶面积,且叶面积建成的消耗较往年叶小。研究认为,异龄叶性状在异龄叶间存在变异与关联,叶面积形成过程中生物量建成与消耗的协调可能影响植物叶片的发育。     

内蒙古荒漠草原优势植物叶形态性状与地上生物量对多资源协同的响应

探究多资源添加数量对荒漠草原优势植物叶片形态特征与生物量的影响,对于揭示荒漠草原植被对全球变化的响应特征和适应规律具重要意义。为分析不同的资源添加的数量是否会影响植物功能性状与地上生物量,通过设置资源添加数量的梯度(0(对照(Cont,自然降水));1(氮(N) 添加、磷(P)添加、钾(K)添加、+50%降水);2(PK添加、NP添加、NK添加、N+50%降水);3(NPK添加);4(NPK+50%降水)),研究多资源添加数量对荒漠草原优势植物碱韭(Allium polyrhizum)和沙生针茅(Stipa glareosa)叶性状及其生物量的影响,为荒漠草原植物响应多种全球变化因子提供理论依据。研究结果表明:(1)碱韭和沙生针茅叶干物质含量(LDMC)与叶片氮含量(LNC)对多资源添加数量响应存在显著差异:随着多资源添加数量增加,碱韭和沙生针茅LMDC显著降低(P < 0.05),但株高和比叶面积没有发生显著改变(P > 0.05)。此外,碱韭叶鲜重和叶片氮含量随着多资源添加数量增加显著升高(P < 0.05),叶鲜重、株高和比叶面积在添加四种资源要素时达到最高,而LDMC则最低。(2)多资源添加数量对两种优势植物地上生物量无显著影响(P > 0.05)。(3)两种优势物种地上生物量与株高、植株密度显著正相关(P < 0.05);与SLA、LDMC和LNC无相关性(P > 0.05)。(4)结构方程模型表明多资源添加数量通过提高碱韭和沙生针茅植株密度、比叶面积和叶片氮含量来间接增加地上生物量。综上所述,相比单一资源添加,多资源添加会对荒漠草原优势植物功能性状和生物量产生复杂影响;在多种资源变化背景下,植物功能性状是预测地上生物量的有效指标,这种研究对于在持续的全球变化背景下管理沙漠草原植被至关重要。     

山西霍山不同功能型植物叶性特征的比较研究

选取山西霍山地区30种主要植物（乔木7种、灌木10种、草本植物13种）,分别测定了其比叶面积（SLA）,单位重量叶氮含量（Nmass）及单位面积叶氮含量（Narea）,初步探讨了3种功能型植物的部分叶性特征,并进行了比较分析。结果表明：在霍山地区这个特定的环境下,草本植物的SLA最大,灌木次之,乔木最小;对于Nmass,同样是草本植物最高,灌木次之,乔木最低;而Narea乔木最高,灌木次之,草本最低,表现出在相同环境下,不同功能型植物的叶性特征的差异性。不同功能型植物的SLA与Nmass呈正相关关系,与Narea呈负相关关系,表现出在相同环境下,不同功能型植物叶性关系的相似性。     

Foliar nutrients in relation to growth, allocation and leaf traits in seedlings of a wide range of woody plant species and types

This study aimed to identify functional correlates of seedling leaf nutrient content among woody species and to characterise functional species groups with respect to leaf nutrient attributes. Seedlings of 81 woody species from the temperate zone of western Europe were grown in a standard laboratory environment with standard, near-optimal nutrient availability. Weight-based leaf N content (N_wght) was positively correlated with mean relative growth rate (RGR), but the correlation with mean RGR was tighter when leaf N was expressed on a whole-plant weight basis: leaf nitrogen weight ratio (LNWR). Area-based leaf N content (N_area) was not associated with mean RGR, but was closely correlated with the quotient of saturated leaf weight and leaf area. Weight-based leaf K content (K_wght) was a close correlate of the saturated/dry weight ratio of the foliage. Within the lower range, K_wght corresponded with growth-related nutrient attributes, but higher values appeared to indicate succulence or remobilisable stored water. Functional groups of species and genera could be distinguished with respect to seedling leaf nutrient attributes. Deciduous woody climbers and scramblers had consistently higher leaf N_wght, LNWR and (apparently) leaf K_wght than other deciduous species or genera, and shrubs had higher values than trees. These differences seemed due partly to variation in specific leaf area. Evergreens had consistently higher leaf N_area than deciduous plants, but there were no significant differences in weight-based leaf nutrient attributes between these two groups, possibly because of `luxury nutrient consumption' by the slow-growing evergreens. Another functional group was that of the nitrogen-fixing species, which had consistently high innate leaf N_wght compared to non-N-fixers. The ecological significance of the leaf nutrient attributes in this study is discussed by comparing the seedling data with those from field-collected material, and by brief reference to the natural habitats of the species. Received: 22 September 1996 / Accepted: 1 March 1997     

木兰科常绿与落叶物种叶片构建策略的差异

为探究木兰科(Magnoliaceae)常绿与落叶物种叶片构建的生理生态策略,选取黄山木兰(Yulaniacylindrica)、玉兰(Y.denudata)和鸡公山玉兰(Y. jigongshanensis) 3种落叶物种,以及荷花玉兰(Magnolia grandiflora)、含笑花(Michelia figo)、石碌含笑(M. shiluensis) 3种常绿物种,对其叶片构建成本和叶片寿命相关的性状进行比较。结果表明,木兰科3落叶种的单位叶片面积成本(CCarea)显著低于3常绿种,但落叶和常绿物种的叶片质量成本(CCmass)差异不显著。落叶物种的叶氮、磷含量(Nmass,Pmass)和比叶面积(SLA)均显著高于常绿物种,而叶片寿命(LLS)显著低于常绿物种。CCarea与LLS呈显著正相关,Nmass、Pmass和SLA均与LLS呈显著负相关。这说明木兰科玉兰属落叶物种单位面积叶片构建成本小于常绿物种;落叶物种叶片寿命短,但采取低成本构建策略,提高比叶面积获得更多光资源,增加营养积累,也揭示了玉兰属落叶物种适应北亚热带较短的生长季和较低水热条件的生理生态策略。     

Leaf lifespan as a determinant of leaf structure and function among 23 amazonian tree species

Summary The relationships between resource availability, plant succession, and species' life history traits are often considered key to understanding variation among species and communities. Leaf lifespan is one trait important in this regard. We observed that leaf lifespan varies 30-fold among 23 species from natural and disturbed communities within a 1-km radius in the northern Amazon basin, near San Carlos de Rio Negro, Venezuela. Moreover, leaf lifespan was highly correlated with a number of important leaf structural and functional characterisues. Stomatal conductance to water vapor (g) and both mass and area-based net photosynthesis decreased with increasing leaf lifespan (r²=0.74, 0.91 and 0.75, respectively). Specific leaf area (SLA) also decreased with increasing leaf lifespan (r²=0.78), while leaf toughness increased (r²=0.62). Correlations between leaf lifespan and leaf nitrogen and phosphorus concentrations were moderate on a weight basis and not significant on an area basis. On an absolute basis, changes in SLA, net photosynthesis and leaf chemistry were large as leaf lifespan varied from 1.5 to 12 months, but such changes were small as leaf lifespan increased from 1 to 5 years. Mass-based net photosynthesis (A/mass) was highly correlated with SLA (r²=0.90) and mass-based leaf nitrogen (N/mass) (r²=0.85), but area-based net photosynthesis (A/area) was not well correlated with any index of leaf structure or chemistry including N/area. Overall, these results indicate that species allocate resources towards a high photosynthetic assimilation rate for a brief time, or provide resistant physical structure that results in a lower rate of carbon assimilation over a longer time, but not both.     

Phenology of the shrub strata of successional sub-tropical humid forests of north-eastern India

The phenology of 70 shrub species occurring in 5-, 25- and 60-yr old forest fallows, developed after slash and burn agriculture in north-eastern India, was studied. The early successional shrubs were largely deciduous with predominant leaf fall during the dry winter, while late successional shrubs were evergreen and with a less pronounced leaf fall pattern; the species in the 25-yr old fallow were largely of the leaf-exchanging-evergreen type. Peak leaf production, flowering and fruiting are delayed by one month in the 60-yr old fallow. The phenological separation of the growth types in the three fallows is discussed and related to possible micro-environmental differences.     

The basis for variation in leaf longevity of plants

Any theory of leaf phenology must predict leaf longevity, leaf habit, leaf expansion and its timing among other variables. These phenological traits may be important keys to understand the response of trees to climatic change. Here I concentrate on and review two of these critical phenological traits, leaf longevity and leaf habit. Theories of leaf longevity were re-evaluated and leaf longevity is concluded to be optimized to maximize plant carbon gain. From this perspective, three points are predicted. Leaf longevity is short when the photosynthetic rate of the leaf is high, when the photosynthetic rate decreases rapidly through time, or when the construction cost of the leaf is small. These predictions are well supported by empirical as well as experimental results on various plant species. The theory, which is extended to seasonal environments, is general and applicable to seasonal as well as aseasonal environments. The theory simulated the bimodal geographic distribution of evergreenness.     

Leaf growth pattern in evergreen and deciduous species of the Central Himalaya,India

Leaf growth patterns were investigated in 11 evergreen (with leaf life-spans of just more than 1 year) and 15 deciduous species, occurring along an elevational gradient of 600–2200 m elevation in the Central Himalaya. Records were made of the leaf initiation period, leaf population dynamics, leaf expansion, leaf mass changes, leaf longevity and related parameters. Species of both groups produced leaves at similar rates during March to April, the driest period of the year. Species of both groups had approximately fully developed foliage during the warm, wet period (mid-June to mid-September) of the monsoon. However, significant differences were found at group level in other characters: shoot length (19.5 cm per shoot for deciduous and 11.7 cm for evergreen species); leaf population per 10 cm shoot length (4.7 vs 15.0); leaf area (107.9 vs 41.4 cm²/ leaf); specific leaf mass (106.9 vs 191.3 g/m²); and leaf mass loss after the monsoon period, being rapid and higher (31.6%) in deciduous species and slow and limited in the evergreens (26.2%). However, species of the two groups showed considerable overlaps in the values of above characters. The evergreen species of the Central Himalaya resembled the deciduous species of the region more than the multi-year leaves of clearly evergreen species. The evergreens bear leaves throughout the year, but like deciduous species bear the cost of annual replacement of old leaves by new leaves. They seem to outcompete deciduous species by producing annually a greater mass of leaves of low-carbon cost (per unit leaf mass), which is capable of conducting photosynthesis all year round. A situation of less marked contrast between favourable and nonfavourable periods, with respect to temperature, seems to favour the leaf characters of the evergreens.