植物性状的研究已经有相当长的历史了,从生态学的角度研究植物性状,最早的经典工作可追溯到1934年Raunkiaer的生活型分类系统。最近的20年来,随着国际上全球变化研究的不断深入,人们将植物功能性状与植物功能型(Plant functional types)两个概念相结合,应用到气候变化对生态系统功能影响的定量分析、模拟和评价中。尤其是近10年来,植物性状相关的新概念和测度方法不断涌现,应用领域也不断拓展,研究的科学问题已经涉及到了生态学研究的许多层面,其中最为关键的问题是植物功能性状与环境的关系及其与生态系统功能的关系,环境如何影响植物的功能性状,植物功能性状如何反映生态系统的过程和功能,从而达到建立环境与生态系统功能之间密切联系的目的。
在此对植物性状和植物功能性状国际研究前沿,包括植物功能性状与环境、生态系统过程和功能之间的关系及其应用等方面进行综述,供国内相关科学工作者参考,以方便国内读者及时了解学科发展动态,推动国内植物功能性状的研究进程。
1 植物功能性状相关术语及分类系统
植物性状是指易于观测或者度量的植物特征,是物种长期进化过程中适应不同环境的结果,能够客观表达植物对外部环境的适应性,如植物高度、叶片大小等(McIntyre et al., 1999)。植物属性也称植物性状,即植物适应外部环境而形成的生物学特征。植物功能性状是能够响应生存环境的变化并(或)对生态系统功能有一定影响的植物性状,如叶片大小和寿命、种子大小和扩散模式、冠层高度等(Díaz & Cabido,2001);它反映了植物在表征生态系统功能方面的生态指示作用,强调其与生态系统过程和功能的关系,而植物性状一般仅限植物自身的结构特征,二者有一定的差异,但由于目前对植物功能性状与生态系统过程与功能关系的认识还十分有限,因此难以划定二者之间的明确界限。植物功能型是对环境因子有相似响应、在生态系统或者生物群区中起相似作用的所有植物种的组合,这种相似性的基础就是它们趋于分享一套关键的植物功能性状(Díaz & Cabido,2001;Cornelissen et al., 2003)。植物功能群(组)(Plant functional groups)实际上等同于植物功能型,部分植物群落生态学家和进化生态学家喜欢使用该名词,它是对某一特征因子有相似响应、具有某些相似性状的物种集合;根据生理、形态、生活史或其它与某一生态系统过程相关以及与物种行为相联系的一些生物学特性来划分,这些性状一般是个体生态学性状,并不一定是分类学性状(孙国钧等,2003)。
植物功能性状的分类方法很多。根据植物对策,可分为植物营养性状(Vegetative traits)和繁殖性状(Regenerative traits);根据与生态系统的关系,可以分响应性状(Response traits)和影响性状(Effect traits),前者反映植物对环境因子(如资源有效性和干扰)的响应,后者决定植物对生态系统功能(如生物地球化学循环和干扰抵抗性)的影响,这两类性状在一定程度上相互重叠(Lavorel & Garnier, 2002);根据其快速测量和定量描述的难易程度可以分为“软性状(Soft traits)”,即那些相对容易获得和量化的特性,如生长型、生活型等,以及“硬性状(Hard traits)”,即那些难以在许多地区和大量植物中定量的特性,如相对生长速率、光合能力等(Cornelissenet al., 2003)。软性状虽然应用广泛,却不易与生态系统功能建立直接联系,而硬性状虽然较难获得,却能更加准确地反映生态系统的功能特征。软性状和硬性状又是相互联系的,而且这种联系在不同的环境条件下是一致的,因此可利用合适的软性状来代替硬性状,用于大尺度的研究中(Hodgson et al., 1999;Lavorel & Garnier, 2002)。
2 植物功能性状与环境
植物性状与环境之间的联系是气候、干扰和生物条件筛选效应的结果(Díazet al., 1998),其研究历史如同生态学本身一样古老。此处我们所涉及到的环境分为自然环境和干扰环境两类,前者主要包括气候(如气温、降水、光照等)、地形地貌(如地理空间梯度变异、海拔高度、坡向等)和营养状况等,后者主要包括火、放牧(包括草食动物啃食)、生物入侵和土地利用等。植物功能性状与环境关系的研究,可为我们研究当前环境条件下的生态系统功能奠定基础,为预测未来全球变化对生态系统的影响提供方法和依据。
2.1 气候
根据经典的植被/植物种与气候的关系,全球、洲际和区域尺度的气候与植物功能性状应该有密切的联系。然而,全球尺度上175个地点2 548个植物种的叶经济谱(叶片的主要化学、结构和生理特征)的研究揭示,单位面积叶质量(Leaf mass per area, LMA)与气候(年平均气温、可能蒸散、水气压亏缺、太阳辐射和降水)间虽然存在某些显著相关,全球总体格局却并不十分明显(Wright et al., 2004a);但如果能够找到合适的气候指标和选择合适的植物性状,可以肯定全球及不同地区植物功能性状与气候的关系应是显著的。在区域尺度上,植物功能性状与气候的关系则比全球尺度更加紧密,但不同区域间和不同性状间也存在不少差异,而且植物营养性状比繁殖性状与气候的关系更紧密些(Díazet al., 1998)。
降水对植物叶性状也具有显著影响,叶片性状的干湿季节差异明显反映了这种影响,比如澳大利亚北部的稀树草原(Prior et al., 2004);在旱季,巴拿马中部地区的热带森林冠层落叶性程度与降水梯度成负相关(Condit et al., 2000)。澳大利亚东南部的多年生植物的叶宽、比叶面积和成熟冠层高度与降水和土壤总含磷量呈正相关(Fonseca et al., 2000)。在新西兰草地上,潮湿的生境能降低光合水分利用率,减小叶和根的组织密度(Craine & Lee, 2003)。植物性状与降水的关系同样存在地区、生态系统和种间差异,比如西班牙东北地区落叶树种葡萄牙橡木(Quercus faginea)叶片性状与降水无显著相关,常绿灌木胭脂虫栎(Q. coccifera)和常绿乔木冬青栎(Q. ilex)部分叶片形态和化学组成性状与降水成正相关,部分性状与降水成负相关(Castro-Díezet al., 1997)。
2.2 地理空间变异
地理空间变异包括地形地貌、海拔、坡度、坡向等,其变化与气候和土壤等的变化密切相关。经向和纬向地形地貌的地理空间变异对植物功能性状的影响主要来自于气温、降水和土壤特性的梯度变化。全球不同生物群区类型(热带森林到温带森林,高山冻原到荒漠)的植物功能性状存在明显差异(Reich et al., 1997,1999;Villar & Merino, 2001);世界主要阔叶林叶性状如比叶面积、叶厚度、氮和磷含量等在不同植被类型之间和相同植被类型内都存在很大差异(Turner,1994);美洲、非洲、印度和澳大利亚地区的季节性干旱热带生态系统有不同的物候性状(常绿、落叶、半落叶、短落叶),木本植物的生理生态性状(气孔导度、光合作用)差异与土壤和大气水分含量相关(Eamus,1999)。
植物生活史和生理性状与植物种分布范围内的土壤水分、土壤营养和火灾体制紧密相关,如美国佛罗里达中北部疏林17种栎属(Quercus)植物(Cavender-Bares et al., 2004);北美8种云杉(Picea)幼苗的相对生长速率、比叶面积与纬度成正相关,叶重比率(Leaf weight ratio, LWR)与干旱度成负相关(Miyazawa & Lechowicz, 2004)。同种植物的叶片形态、解剖和水分性状在不同地点间可明显不同,如意大利的冬青栎幼苗(Gratani et al., 2003)。果实大小和种子质量也存在地理变异,如日本的栲属植物(Castanop-sis),环境适合母树生长则坚果较大(Yamada & Miyaura, 2005);北美8种云杉种子质量与纬度呈负相关(Miyazawa & Lechowicz, 2004)。
海拔高度对植物功能性状的影响也是多种因素的综合作用。新西兰南岛118种植物随着海拔升高,叶和根的氮含量降低、厚度增加(Craine & Lee, 2003);德国黑森州北部4个树种随海拔升高其高度增量减小、叶大小和叶面积降低、气孔密度增加(Hølscheret al., 2002)。生活型丰富度和海拔高度成负相关,墨西哥一个半干旱河谷中小高位芽植物、柱状仙人掌植物、肉质植物和地上芽植物的丰富度与海拔高度和土壤氮含量明显相关(Pavónet al., 2000),阿根廷火地岛(Tierra del Fuego)南部高山地区不同海拔高度以及南北两坡的植物生活型分布显著不同(Mark et al., 2001),表明沿海拔梯度的环境变化限制着生活型的分布。
2.3 营养
2.4 干扰
2.4.1 火灾
植物对火灾的响应策略可分为火灾前和火灾中的逃避策略(生存适应对策)及火灾后的萌芽重生策略,并对不同层位的森林火有不同的适应性状。迟季结果和早开花是对火的逃逸对策,有利于松树在频繁的冠层火中生存下来和火后成功重生;高度迟季性和薄树皮是对频繁的林分替换冠层火(Stand-replacing crown fire)的适应;而厚树皮个体则有能力生存于地面火中(Tapias et al., 2004)。对于冠层火生态系统来说,与火后留存相关的植物性状主要包括再萌芽能力(个体持续)和保存一个持久种子库的能力(种群持续)(Pausas et al., 2004)。而植物种无法完全划分为萌生者和非萌生者,只能称之为弱萌生植物和强萌生植物,澳大利亚东南部45种不同生长型植物(禾草、杂类草、半灌木、木本灌木、乔木)中禾草萌生能力最强,藜科植物较弱,杂类草和木本植物则有强有弱(Vesk et al., 2004b),萌生能力与植物的大小成正比,且一定程度上与生长型相关。
2.4.2 放牧
放牧是一个不太强烈但很连续的干扰形式,可以强烈破坏或改变自然植被,尤其是草原生态系统。然而,草原植物对家畜放牧的响应存在明显差异,我们对放牧影响植被变化的预测能力还非常有限(Vesk et al., 2004a)。
在遭受放牧干扰时,具有适应性状的物种会继续存活,而不适应的物种则可能会被淘汰,具有不同性状的植物群相对优势度会发生变化。全球不同地区草地(葡萄牙牧场、苏格兰草地、以色列草本群落、澳大利亚昆士兰亚热带多草桉树疏林草场和亚热带干旱牧场、乌拉圭塞罗拉尔戈(Cerro Largo)平原地区天然草地以及阿根廷山区草地)等受干扰植被的研究不同程度地表明,放牧强度增加时,一年生生活史、适度休眠、杂草、地下芽、小个体、矮分生组织、匍匐莲座冠层结构、小光合结构、高光需求、小叶、有覆被的叶、大比叶面积、受保护花序、小种子、季节性种子繁殖、早开花和早散布种子、高的再生长潜力、对放牧响应的可塑性和高繁殖力等性状明显增加;生活史、生活型、无性和有性繁殖等性状对放牧的响应还受到生产力的调节,在不同地点和物种间也可能有一定的变化(Landsberg et al., 1999;Lavorel et al., 1999;Díazet al., 2001;McIntyre & Lavorel, 2001;Rodríguezet al., 2003;Pakeman,2004)。不仅放牧强度而且放牧时间的长短也影响植物性状对放牧的响应。阿根廷和美国西北部草原的植物形态性状与叶片化学成分对放牧历史长短的响应有显著差异,阿根廷巴塔戈尼亚(Patagonia)草原的低饲草质量(低叶片延展性、纤维和氮素含量)明显指示着该地区的长期放牧历史(Adler et al., 2004)。
2.4.3 生物入侵
2.4.4 土地利用
3 植物功能性状与生态系统过程和功能
植物功能性状之间相互关联,不同植物区系间可能存在相似的性状格局;多个性状的结合决定着植物之间的关系以及植物种与群落和生态系统功能之间的相互作用,也影响着生物多样性与生态系统功能之间的联系(Reich et al., 1997,1999;Díaz & Cabido,2001;Villar & Merino, 2001;Craine et al., 2002;Westoby et al., 2002;Eviner & Chapin, 2003;Chown et al., 2004;Díazet al., 2004),这种联系的建立以植物功能型作为媒介,根据特有的植物功能性状组合来划分植物功能型,利用植物功能型来描述植物群落或生态系统的格局和过程,从而建立植物功能性状与群落和生态系统结构与功能之间的联系,为研究和预测植被和生态系统对全球变化的响应提供了一个有力的工具(Díaz & Cabido,1997;Lavorel & Garnier, 2002)。
3.1 性状相互关系
多种叶性状之间关系紧密。不同生态系统和众多物种数据的综合分析都表明,叶片寿命与比叶面积、植物整体叶面积比、光合能力、叶片氮和磷含量成显著负相关(Reich & Walters, 1992;Wright & Westoby, 2003;Wright et al., 2004b),与单位面积叶质量成正相关(Wright et al., 2002);比叶面积、光合作用能力、暗呼吸、气体交换性状、叶片氮和磷含量相互之间成正相关(Wright et al., 2004a)。德国8种禾草植物叶片的伸长速率与比叶面积成正相关,与叶片干物质含量成负相关(Arredondo & Schnyder, 2003)。亚州东南部8种演替早期热带树种的最大气孔导度与叶面积和叶片氮含量密切相关,其中与叶大小呈显著负相关(Juhrbandt et al., 2004)。比叶面积和叶干物质含量间成负相关,它们尤其是叶干物质含量是量化植物功能的最佳性状,可代替相对生长速率等硬性状,用于大尺度的监测和研究(Garnier et al., 2001;Vendramini et al., 2002;Roche et al., 2004)。叶或根的组织密度、木质素含量、厚度(直径)与它们的氮含量成负相关。叶性状和根性状间联系较小,在区域尺度上仅两者的氮含量正相关、δ15N含量正相关,如在新西兰、澳大利亚、南非和北美4个草原区;在全球尺度上两组性状间的关系则由土壤冰冻和营养限制类型等因素决定,C4禾草的叶和根的氮含量都比C3禾草的低(Craine et al., 2005)。
3.2 物种分布
竞争能力和克隆扩散能力是限制物种分布范围的主要性状。较大的高度、叶面积和克隆生长范围、更高的种子产量和形成更大更长久的土壤种子库的能力使得美国的Solidago altissimo具有比同属种S. shortii更强的竞争力和克隆能力,分布范围更广(Walck et al., 2001);而扩散能力(而非繁殖能力)是限制某些森林植物种克隆的关键因子(Verheyen et al., 2003)。比叶面积也与物种的分布格局紧密相关,加拿大范库弗峰岛上6种石南属(Erica)植物,低比叶面积(SLA)的物种在沼泽中更丰富,高SLA的物种在森林中更丰富(Burns,2004)。物种分布格局与哪些植物功能性状相关依赖于物种生存环境和研究尺度,但与种子产量的关系在各种环境和尺度上的一致性最强(Murray et al., 2002)。
3.3 演替和竞争
植物功能性状会随演替进程而发生变化,如植物高度、叶片沿茎干的分布、营养扩展、开花时间、种子质量、比叶面积、叶干物质含量、叶氮含量、叶寿命、叶片出现和脱落的时间等性状,但这些变化与物种组成和具体演替状态的关系还没有一致结论(Navas et al., 2003;Garnier et al., 2004;Kahmen & Poschlod, 2004)。某些植物性状的组合可以决定一个植物种的生活史对策和竞争能力,如最大枝条质量、茎质量、繁殖质量、茎分配、叶面积、比叶面积、生长高度和直径、叶面积比等与植物大小相关的性状(Røschet al., 1997)。植物结构性状(如叶面积)和生理性状(如叶片光合作用速率)对竞争的贡献较大,如高叶面积和较高的叶光合作用速率使得黑麦草属(Lolium)的竞争能力远强于羊茅(Festuca)(Teughels et al., 1995)。
3.4 植物定居和生长
根性状在植物的营养吸收和生长中起着关键作用。生长迅速的物种根可能更有利于快速地开发土壤和更快地更新,与生长缓慢植物相比它们的比根长大、根直径小、分支程度大、酚浓度低,而根组织密度、呼吸作用和磷的吸收的差异随比较的物种不同而不同,如美国宾夕法尼亚州中部多种落叶阔叶树和常绿针叶树(Comas & Eissenstat, 2004)。
某些形态性状如直立与匍匐习性、无性繁殖能力、叶片长宽比例、活跃生长季节可影响乌拉圭中南部草地群落优势种的空间动态变化(不变、短距离扩展、长距离扩展)(Altesor et al., 1999)
3.5 生产力、碳循环和资源利用
生态系统的净第一性生产力、凋落物分解速率、土壤总碳和总氮含量与群落的叶片功能性状相关,比叶面积、叶片干物种含量、氮浓度可以作为法国南部地中海地区生态系统的“功能标记物(Functional markers)”(Garnieret al., 2004)。菌根类型在某种程度上决定了英国的83种植物幼苗的相对生长速率、叶片营养浓度和叶片凋落物的分解能力,菌根类型的联合可以用来解释植物碳循环性状的变异,如植被生产力和凋落物周转(Cornelissen et al., 2001)。美国科罗拉多高山草甸冻原(Miller & Bowman, 2002)和日本北部低地苔草沼泽(Nakamura et al., 2002)的不同植物通过不同的氮利用性状来利用多种有机和无机氮资源。
不同植物在影响生态系统功能上存在差异,大多数物种都有影响生态系统的独特性状组合,单一性状或者单一功能群无法代替这些性状组合的作用,也不能预测不同物种表现出来的多种功能(Eviner & Chapin, 2003)。不同的性状组合联系着不同的生态系统特征,例如单位面积叶质量——叶片寿命与营养周转和对环境的响应相关,种子质量——种子产量与散播和定居相关,叶片大小——嫩枝大小与冠层结构相关,而植物体高度包含多个方面的适应和平衡,具有重要的生态学意义(Westobyet al., 2002)。这些植物功能性状在不同的气候带和不同的景观内样点类型间有差异,与植物对物理环境的适应有关,不同植物对策也与资源利用有关(Westoby,1998;Wilson et al., 1999;Craine et al., 2002;Vendramini et al., 2002)。
4 植物功能性状与全球变化
4.1 气候变化
美国犹他州东北地区的干旱可延长多年生荒漠草本植物的叶寿命,降低新叶产量(Casper et al., 2001)。不同物种对气候变化的响应不同,在北极地区灌木和草本对温度升高是最敏感的;不同物种间的响应差异可能会改变它们的竞争力,甚至改变生态系统的结构和功能(Dormann & Woodin, 2002;Penuelas et al., 2002)。除了平均气候的影响,气候变异性如北大西洋涛动(North Atlantic Oscillation,NAO)也与植物的物候期显著相关,正的NAO(暖湿)冬季使得挪威地区的植物开花期提前,草本植物比木本植物对NAO更敏感,早开花植物比晚开花植物更容易受到气候变异性的影响(Post & Stenseth, 1999)。
4.2 CO2浓度升高
CO2浓度升高能引起生理学性状的明显变化(Dormann & Woodin, 2002),如光合速率、光补偿点、叶的暗呼吸、叶氮含量、比叶面积、叶面积比、气孔密度、叶的形态结构、生态系统中不同形态叶所占的比例和不同植物部位间的生物质分配等性状(Teughels et al., 1995;Hättenschwiler,2001)。大气CO2浓度升高可能会提高碳同化能力和旱地多年生灌木的成活率,但它可能不会抵消长期干旱对死亡率的影响(Housman et al., 2003)。植物对CO2浓度升高的响应存在种间差异 (Hunt et al., 1991;Poorter,1993)。美国明尼苏达州具有不同光合作用途径(C3、C4禾草)和不同固氮性状(豆科、非豆科杂类草)的16种植物中,CO2浓度升高导致杂类草、豆科植物和C3禾草生物量增加,C4植物生物量减少(Craine et al., 2001;Reich et al., 2001)。
5 中国植物功能性状研究
植物性状或者属性的研究贯穿于我国植物生态学发展的各个阶段,只是前期的工作没有把“Traits”这个概念明确提出来,近期的工作虽然明确了“Traits”概念,但其功能特征体现不完全,植物功能性状的研究刚刚处于起步阶段。
在青藏高原,随海拔高度增加,冠层平均叶寿命、基于面积的叶氮含量、叶面积指数、叶氮库都相应增加,而冠层平均比叶面积、基于质量的叶氮含量都下降。温度和降水是驱动这些性状变化的主要因子,土壤有机碳和总氮含量也有重要作用(Luo et al., 2005)。He等(2006)的研究也表明在青藏高原植物的叶片氮含量和光合能力较全球平均数据高,而单位面积叶质量和在指定基于质量的氮含量下基于质量的叶片光合能力稍低,但是各叶性状间的关系与全球尺度下的关系格局相一致。韩文轩等(Han et al., 2005)对全国753个物种的综合分析表明,植物叶片的氮和磷含量随海拔升高而增加,氮和磷比值没有明显变化;虽然中国植被的氮和磷比值较全球平均值高,但中国各个植物功能群间的氮、磷含量及氮和磷的比值与全球水平较一致,这些性状在中国植被中存在一定的生物地理格局。张林和罗天祥(2004)综述了叶寿命及其相关叶性状如比叶面积和叶氮含量间的相互关系以及这些性状对环境的适应策略,并介绍了叶寿命模型,具有重要的指导意义。
放牧是我国北方草原的主要干扰形式。科尔沁沙质草地上,禾本科植物的平均盖度对重牧敏感,牧草高度随放牧强度的增加有规律的降低,且多年生牧草的高度对放牧强度最敏感(张铜会等,2004)。C3和C4植物对放牧的耐受程度不同,C4植物更能耐受由放牧导致的环境胁迫(干旱和盐化等),草地物种中C4植物的比例和C4/C3植物的比值均随放牧强度增加而增加(Wang,2002d)。草地利用方式对群落组成也有明显影响,如能影响植物生物量的积累(白永飞等,2002)。黄土高原自然植被演替早期和中期优势植物种的具体性状和与土壤营养元素变化相关的植物性状,如生活史对策、克隆能力、扩散能力、种子传播模式等也进行了研究(Wang,2002b)。此外,刘志民等(2002)综述了干扰与植被的关系,从多方面论述了植物种对干扰的适应,如种子性状、再萌芽能力、物候、形态特征、生活史等。
6 研究展望
植物功能性状在植被生态学、全球变化生态学、恢复生态学和古生态学等领域应用广泛。在植被模型与模拟方面,陆地生态系统对全球变化的响应模拟研究需要以植物功能型作为植物种和生态系统之间的桥梁,而划分植物功能型的主要依据之一就是植物功能性状(Díaz & Cabido,1997;Roderick et al., 2000;Lavorel & Garnier, 2002)。植物功能性状还用于许多其它模型研究中,如不同火烧制度对以不同性状为特征的植物功能群的影响模拟(Franklin et al.,2001)以及利用植物功能性状和植物功能型相结合预测火灾对生态系统的影响(Pausas,1999;Boer & Stafford Smith, 2003;de Groot et al.,2003)、预测木本植物在顶极森林群落中的优势度(Koike,2001)和利用植物生活史性状模拟物种灭绝时间(Wilcox & Possingham, 2002)等。
在气候与植被重建方面,根据某些植物性状与现代气候的关系可以估测现代气候特征,如在美国佛罗里达和康乃提克木本植物的叶片形态和木材解剖性状与年平均气温关系密切,由此可建立统计模型模拟现代气候特征(Wiemann et al., 2001)。这种植物性状与气候因子的关系应用可以拓展到孢粉研究中,利用表土花粉反推现代气候,利用地层花粉定量重建古气候。如地中海地区602个地点的表土花粉植物性状与植物有效湿度和冬季最冷月平均温度有很好的相关性,由此可建立孢粉与气候的定量关系(Barboni et al., 2004)。同样,植物性状可以刻划孢粉类群的特征,用以定量重建古植被类型和分布格局,这在欧洲地区已经得到很好的应用(Gachet et al., 2003;Gritti et al., 2004)。
在环境监测与评价、生态保护和恢复方面,植物性状的变异可以作为监测环境质量的有效生物学工具。澳大利亚葡萄藤的最大节间长度、叶片大小和叶片形状的变化是对盐胁迫比较敏感的响应,可作为葡萄园含盐度的监测工具(Sinclair & Hoffmann, 2003)。土地退化、荒漠化和过度放牧等环境问题也可以利用植物功能性状特征进行评价。通过把15种多年生植物的性状归并为3类:竞争能力、胁迫耐受性和杂草性,可以揭示非洲北部干旱区的植被变化,从而评价土地退化和生态恢复问题(Jauffret & Visser, 2003)。英国低地草原生态恢复的成效可以用相关植物性状作为指示,在植被恢复过程中能够成功定居和生存发展下去的植物需要好的拓展能力、强竞争力、无性繁殖能力和肥沃的生境(Pywell et al., 2003)。
为更好地研究植物功能性状与环境、生态系统功能之间的关系,更好地利用它们作为生态规划、自然保护和生态恢复等的有用工具,科学家们已经和正在努力建设植物性状库(Trait base),如欧洲西北部植物区系的生活史性状库LEDA(Life-history traits of the Northwest European flora:a database, www.Leda-database.org),选择了26种植物性状来描述植物动态变化的关键特征(Knevel et al., 2003)。另一个与入侵生态学有关的植物性状库为BiolFlor(www.Biolflor.de),该性状库包含了德国3 659个植物种的450 000条记录,将植物总体分为本地种和外来种,对66个性状进行了描述。
植物功能性状及其与环境、生态系统结构和功能的研究虽然已经取得了很多进展,建立起了一套有效的研究方法和理论体系,但仍然有许多问题需要解决。首先,要根据具体的研究环境、时空尺度和目的来选择合适的功能性状;由于性状间相互联系,必须采用多个性状才能建立全面的植物功能性状与环境、生态系统功能之间的联系。其次,目前很多植物功能性状的测量方法还不成熟,很多性状较难获得,如茎干性状、地下性状等,测量方法和技术手段还需要改进。再者,自然环境是复杂多样的,某个因子的驱动作用往往与其它多个环境因子相互牵连,因此植物功能性状与环境的关系需要考虑多因子的共同作用。而且,很多生态系统功能之间也是相互关联的,其与植物功能性状的关系也是多层次、多时空尺度的;尤其是目前人类活动所造成的全球变化对环境的影响日渐突出,研究人为干扰和环境变化对植物功能性状的影响就更为重要。
我国有着特殊的气候、植被条件,又有着长期的人为干扰和土地利用历史,为植物功能性状的研究提供了得天独厚的优势,既可进行国家尺度和温度、降水等气候梯度上的研究,又可进行区域和局域尺度的探讨。为此,应逐步建立和完善适合于我国的功能性状体系和研究方法,在不同的时间和空间尺度上进行细致的植物性状和植物功能性状研究,为揭示我国植被格局变化的环境和生态系统过程驱动机制、更好的进行生态保护和生态恢复奠定良好的基础。
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Functional traits of graminoids in semi-arid steppes: a test of grazing histories
The advantages of being evergreen
Recent research shows that the dominance of evergreen species in nutrient-poor environments can be explained by their low nutrient loss rates. From this work It appears that the plant traits that are associated with low nutrient loss rates lead to low maximum-dry-matter production and to low rates of litter decomposition. This suggests a positive feedback between the evergreen habit and low nutrient availability. The growth characteristics of evergreens lead to a low responsiveness to environmental changes. As a result, global warming may lead to changes in the distribution of evergreens.
Relationship between spatial strategies and morphological attributes in a Uruguayan grassland: a functional approach
Components of leaf elongation rate and their relationship to specific leaf area in contrasting grasses
Responses of spring phenology to climate change
Changes in plant functional composition along gradients of precipitation and temperature in the Xilin River Basin, Inner Mongolia
用样带法调查了草原群落植物功能群组成沿水热梯度的变化。结果表明，随着海拔高度的降低，降水量的减少，热量和干燥度的增加，群落植物生活型功能群组成中，多年生杂类草的相对多度逐渐减少，而多年生丛生禾草的相对多度逐渐增加，多年生丛生禾草对多年生杂类草具有强烈的生态替代作用。在植物生态类群功能群组成中，中旱生植物的作用逐渐减弱，而旱生植物的作用显著增强。草地的利用方式对群落组成具有重要的影响，永久样地和割草场中不耐牧种的相对生物量显著地高于放牧场，而放牧场中耐牧种的相对生物量则显著地高于永久样地和割草场。受草地利用
Relationships between plant traits and climate in the Mediterranean region: a pollen data analysis
A plant functional approach to the prediction of changes in Australian rangeland vegetation under grazing and fire
Patterns in specific leaf area and the structure of a temperate heath community
Drought prolongs leaf life span in the herbaceous desert perennial Cryptantha flava
Seed mass versus seedling performance in Scots pine: a maternally dependent trait
Trade-offs between phenology, relative growth rate, life form and seed mass among 22 Mediterranean woody species
Mediterranean woody plants exhibit a wide phenological diversity which cannot be explained just on the basis of climatic constraints. We assessed the role of relative growth rate (RGR), life form, seed and fruit mass as potential constraints of plant phenology. In a comparison of traits of 22 Mediterranean woody plant species, the duration of the primary shoot growing period decreased from climbers to shrubs and to trees. A hypothesised negative association between RGR and primary shoot growth duration did not emerge in our species set. The mechanism underlying phenological differences between plant life forms might relate to differences in the proportion of respiring to photosynthetic tissues, which decreases from climbers to trees. It is suggested that the degree of shoot preformation within the bud correlates with primary shoot growth duration, but not with RGR. Development of big fruits and seeds competes for carbon with vegetative growth. Indeed, species with bigger seeds and fruits exhibited shorter primary shoot growing periods, which tended to overlap with flower bud formation and flowering periods. We suggest that duration of primary shoot growth allow to short out the species between two extreme growth strategies: The conservative one would be characterised by a concentration of the primary shoot growth into a short period, free of frosts and droughts, and by a diversion of part of the current resources to assure next year's growth. The opportunistic strategy, on the other extreme, would be defined by the allocation of resources to current growth whenever they are available, achieving longer growing periods at the expense of higher risk of tissue damage. These strategies should have been selected for in environments of predictable and unpredictable resource availability, respectively.]]>
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The ecology of leaf life spans
Macrophysiology: large-scale patterns in physiological traits and their ecological implications
Linking fine root traits to maximum potential growth rate among 11 mature temperate tree species
Quantifying the deciduousness of tropical forest canopies under varying climates
Carbon cycling traits of plant species are linked with mycorrhizal strategy
Ecosystem carbon cycling depends strongly on the productivity of plant species and the decomposition rates of the litter they produce. We tested the hypothesis that classifying plant functional types according to mycorrhizal association explains important interspecific variation in plant carbon cycling traits, particularly in those traits that feature in a hypothesized feedback between vegetation productivity and litter turnover. We compared data from standardized 'screening' tests on inherent potential seedling relative growth rate (RGR), foliar nutrient concentrations, and leaf litter decomposability among 83 British plant species of known mycorrhizal type. There was important variation in these parameters between mycorrhizal plant types. Plant species with ericoid mycorrhiza showed consistently low inherent RGR, low foliar N and P concentrations, and poor litter decomposability; plant species with ectomycorrhiza had an intermediate RGR, higher foliar N and P, and intermediate to poor litter decomposability; plant species with arbuscular-mycorrhiza showed comparatively high RGR, high foliar N and P, and fast litter decomposition. Within the woody species subset, differentiation in RGR between mycorrhizal types was mostly confounded with deciduous versus evergreen habit, but the overall differentiation in litter mass loss between mycorrhizal types remained strong within each leaf habit. These results indicate that, within a representative subset of a temperate flora, ericoid and ectomycorrhizal strategies are linked with low and arbuscular-mycorrhizal species with high ecosystem carbon turnover. The incorporation of mycorrhizal association into current functional type classifications is a valuable tool in the assessment of plant-mediated controls on carbon and nutrient cycling.
A handbook of protocols for standardized and easy measurement of plant functional traits worldwide
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Grassland species effects on soil CO 2 flux track the effects of elevated CO 2 and nitrogen
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Response to CO 2 enrichment in 27 herbaceous species
Tree seedling growth in natural deep shade: functional traits related to interspecific variation in response to elevated CO 2
The mechanisms for species-specific growth responses to changes in atmospheric CO2 concentration within narrow ecological groups of species, such as shade-tolerant, late-successional trees, have rarely been addressed and are not well understood. In this study the underlying functional traits for interspecific variation in the biomass response to elevated CO2 were explored for seedlings of five late-successional temperate forest tree species (Fagus sylvatica, Acer pseudoplatanus, Quercus robur, Taxus baccata, Abies alba). The seedlings were grown in the natural forest understorey in very low and low light microsites (an average of 1.3% and 3.4% full sun in this experiment), and were exposed to either current ambient CO2 concentrations, 500, or 660 microl CO2 l(-1) in 36 open-top chambers (OTC) over two growing seasons. Even across the narrow range of successional status and shade tolerance, the study species varied greatly in photosynthesis, light compensation point, leaf dark respiration (R d), leaf nitrogen concentration, specific leaf area (SLA), leaf area ratio (LAR), and biomass allocation among different plant parts, and showed distinct responses to CO2 in these traits. No single species combined all characteristics traditionally considered as adaptive to low light conditions. At very low light, the CO2 stimulation of seedling biomass was related to increased LAR and decreased R d, responses that were observed only in Fagus and Taxus. At slightly higher light levels, interspecific differences in the biomass response to elevated CO2 were reversed and correlated best with leaf photosynthesis. The data provided here contribute to a mechanistic process-based understanding of distinct response patterns in co-occurring tree species to elevated CO2 in natural deep shade. I conclude that the high variation in physiological and morphological traits among late-successional species, and the consequences for their responses to slight changes in resource availability, have previously been underestimated. The commonly used broad definitions of functional groups of species may not be sufficient for the understanding of recruitment success and dynamic changes in species composition of old-growth forests in response to rising concentrations of atmospheric CO2.
Growth and leaf traits of four broad-leaved tree species along a hillside gradient
Assigning life-history traits to plant species to better qualify arid land degradation in Presaharian Tunisia
The relationship between maximal stomatal conductance and leaf traits in eight Southeast Asian early successional tree species
Plant functional trait responses to grassland succession over 25 years
Life history traits of the Northwest European flora: the LEDA database
Plant traits as predictors of woody species dominance in climax forest communities
Invasion success of exotic plants in natural ecosystems: the role of disturbance, plant attributes and freedom from herbivores
Grazing response groups among understory plants in arid rangelands
Predicting changes in community composition and ecosystem functioning from plant traits: revisiting the Holy Grail
Plant response to disturbance in a Mediterranean grassland: how many functional groups?
How well do plant traits correlate with establishment ability? Evidence from a study of 16 calcareous grassland species
Relationship between disturbance and vegetation
Leaf traits and associated ecosystem characteristics across subtropical and timberline forests in the Gongga Mountains, Eastern Tibetan Plateau
Landscape and species-level distribution of morphological and life history traits in a temperate woodland flora
Vegetation patterns, plant distribution and life forms across the alpine zone in southern Tierra del Fuego, Argentina
Livestock grazing in subtropical pastures: steps in the analysis of attribute response and plant functional types
Disturbance response in vegetation—towards a global perspective on functional traits
Plant life-history attributes: their relationship to disturbance response in herbaceous vegetation
Variation in nitrogen-15 natural abundance and nitrogen uptake traits among co-occurring alpine species: do species partition by nitrogen form?
In the N-limited alpine tundra, plants may utilize a diversity of N sources (organic and inorganic N) in order to meet their nutritional requirements. To characterize species-level differences in traits related to N acquisition, we analyzed foliar delta(15)N, nitrate reductase activity (NRA) and mycorrhizal infection in co-occurring alpine species during the first half of the growing season and compared these traits to patterns of N uptake using a (15)N ((15)N-NH4(+), (15)N-NO3(-)) or (13)C,(15)N ([1]-(13)C-(15)N-glycine) tracer addition in the greenhouse. (13)C enrichment in belowground tissue indicated that all species were capable of taking up labeled glycine, although only one species showed uptake of glycine potentially exceeding that of inorganic N. Species showing the most depleted foliar delta(15)N and elevated NRA in the field also tended to show relatively high rates of NO3(-) uptake in the greenhouse. Likewise, species showing the most enriched foliar delta(15)N also showed high rates of NH4(+) uptake. The ratio of NO3(-):NH4(+) uptake rates and growth rate explained 64% and 72% of the variance in foliar delta(15)N, respectively, suggesting that species differ in the ability to take up NO3(-) and NH4(+) in the field and that such differences may enable species to partition soil N on the basis of N form.
Comparative seeding ecology of eight North America Spruce ( Picea) species in relation to their geographic ranges
BACKGROUND AND AIMS: Allowing for dispersal limitation, a species' geographic distribution should reflect its environmental requirements. Comparisons among closely related species should reveal adaptive differentiation in species characteristics that are consistent with their differences in geographic distribution. This expectation was tested by comparing characteristics of seedlings of spruce species in relation to environmental factors representative of their current natural ranges. METHODS: Seedlings were grown from a total of 34 populations representing eight North American spruce (Picea) species in a controlled environment chamber for 140 d. Traits related to the potential of seedling establishment, including tolerance to stress events (high temperature, desiccation) were evaluated. Correlations were sought between these characteristics and modal values of latitude, aridity and continentality in the geographic range of each species. KEY RESULTS: Many seedling traits changed significantly in response to stress events, but only the response of chlorophyll concentration differed significantly among species. Components of seedling growth were good correlates of species distribution. Seedling relative growth rate (RGR) and specific leaf area (SLA) were positively correlated with latitude, and leaf weight ratio (LWR) negatively correlated with aridity. Seed mass was negatively correlated with latitude. CONCLUSIONS: Relationships found between seedling traits and geographical variation in environmental conditions suggest that factors such as temperature regime, water availability and perhaps litter depth affect species range in North American spruces. Seedling characteristics appear to be elements in a reasonably distinct environmental niche for each spruce species at the continental scale.
Small-seeded species produce more seeds per square metre of canopy per year, but not per individual per lifetime
Seedling survival and seed size: a synthesis of the literature
Geographical gradients in seed mass in relation to climate
How plant life-history and ecological traits relate to species rarity and commonness at varying spatial scales
Variation in nitrogen-use traits within and between five Carex species growing in the lowland mires of Northern Japan
Leaf life span, dynamics and construction cost of species from Mediterranean old-field differing in successional status
Reproductive traits of Pinus halepensis in the light of fire—a critical review
Consistency of plant species and traits responses to grazing along a productivity gradient: a multi-site analysis
Response of plant functional types to changes in fire regime in Mediterranean ecosystems: a simulation approach
Plant functional traits in relation to fire in crown-fire ecosystems
Distribution of plant life forms along an altitudinal gradient in the semi-arid valley of Zapotitlán, Mexico
Changed plant and animal life cycle from 1952 to 2000 in the Mediterranean region
Architecture of 53 rain forest tree species differing in adult stature and shade tolerance
Interspecific variation in the growth response of plants to an elevated ambient CO 2 concentration
Climatic variability, plant phenology, and northern ungulates
Seasonal differences in leaf attributes in Australian tropical tree species: family and habitat comparisons
C 4 plants in the vegetation of Mongolia: their natural occurrence and geographical distribution in relation to climate
The natural geographical occurrence, carbon assimilation, and structural and biochemical diversity of species with C4 photosynthesis in the vegetation of Mongolia was studied. The Mongolian flora was screened for C4 plants by using (13)C/(12)C isotope fractionation, determining the early products of (14)CO2 fixation, microscopy of leaf mesophyll cell anatomy, and from reported literature data. Eighty C4 species were found among eight families: Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Molluginaceae, Poaceae, Polygonaceae, Portulacaceae and Zygophyllaceae. Most of the C4 species were in three families: Chenopodiceae (41 species), Poaceae (25 species) and Polygonaceae, genus Calligonum (6 species). Some new C4 species in Chenopodiaceae, Poaceae and Polygonaceae were detected. C4 Chenopodiaceae species make up 45% of the total chenopods and are very important ecologically in saline areas and in cold arid deserts. C4 grasses make up about 10% of the total Poaceae species and these species naturally concentrate in steppe zones. Naturalized grasses with Kranz anatomy,of genera such as Setaria, Echinochloa, Eragrostis, Panicum and Chloris, were found in almost all the botanical-geographical regions of Mongolia, where they commonly occur in annually disturbed areas and desert oases. We analyzed the relationships between the occurrence of C4 plants in 16 natural botanical-geographical regions of Mongolia and their major climatic influences. The proportion of C4 species increases with decreasing geographical latitude and along the north-to-south temperature gradient; however grasses and chenopods differ in their responses to climate. The abundance of Chenopodiaceae species was closely correlated with aridity, but the distribution of the C4 grasses was more dependent on temperature. Also, we found a unique distribution of different C4 Chenopodiaceae structural and biochemical subtypes along the aridity gradient. NADP-malic enzyme (NADP-ME) tree-like species with a salsoloid type of Kranz anatomy, such as Haloxylon ammodendron and Iljinia regelii, plus shrubby Salsola and Anabasis species, were the plants most resistant to ecological stress and conditions in highly arid Gobian deserts with less than 100 mm of annual precipitation. Most of the annual C4 chenopod species were halophytes, succulent, and occurred in saline and arid environments in steppe and desert regions. The relative abundance of C3 succulent chenopod species also increased along the aridity gradient. Native C4 grasses were mainly annual and perennial species from the Cynodonteae tribe with NAD-ME and PEP-carboxykinase (PEP-CK) photosynthetic types. They occurred across much of Mongolia, but were most common in steppe zones where they are often dominant in grazing ecosystems.
Plant traits as predictors of performance in ecological restoration
Generality of leaf trait relationships: a test across six biomes
Do species and functional groups differ in acquisition and use of C, N and water under varying atmospheric CO 2 and N availability regimes?A field test with 16 grassland species
Leaf demography and phenology in Amazonian rain forest: a census of 40000 leaves of 23 tree species
Leaf life-span in relation to leaf, plant, and stand characteristics among diverse ecosystems
From tropics to tundra: global convergence in plant functioning
Congruency analysis of species ranking based on leaf traits: which traits are the more reliable?
A framework for understanding the relationship between environment and vegetation based on the surface area to volume ratio of leaves
Temporal trends in species composition and plant traits in natural grasslands of Uruguay
Predicting competitive interactions between pioneer plant species by using plant traits
The functional morphology of juvenile plants tolerant of strong summer drought in shaded forest understories in Southern Spain
Tree and forest functioning in response to global warming
Monitoring salt stress in grapevines: are measures of plant traits variability useful?
Crown development in tropical rain forest trees: patterns with tree height and light availability
Trends and advance in researches on plant functional diversity and functional groups
What makes a weed a weed: life history traits of native and exotic plants in the USA
I compared ten life history traits (vegetative reproduction, breeding system, compatibility, pollination system, shade tolerance, habitat, life span, life form, morphology, and toxicity) from two existing databases for the 19,960 plant species that occur in the USA. I used two-way tests of independence to determine if there were significant life history traits that distinguish weeds from non-weeds, exotic weeds from native weeds, and invasive exotic weeds from non-invasive exotic weeds. Life span was the most significant life history trait for weeds in general; weeds were more likely to be annuals and biennials and less likely to perennials than non-weeds. In addition, vegetative reproduction, breeding system, compatibility, shade tolerance, and life form were related to life span. Annual and biennial weeds (whether native, exotic, or exotic invasives) were more likely to be wetland adapted, armed, and toxic than annual or biennial non-weeds. Perennial weeds (whether native, exotic, or exotic invasives) were less likely to be forbs or subshrubs, and more likely to be wetland adapted, toxic, shade intolerant, grasses, vines and trees than perennial non-weeds. Exotic annual and perennial weeds were less likely to be wetland species than native weeds, but more likely to be wetland species than non-weeds. Invasive exotic weeds, in contrast, were less likely to be forbs and more likely to be perennial, monoecious, self-incompatible, and trees and than non-invasive exotics.
Life histories of Mediterranean pines
Competition in a global change environment: the importance of different plant traits for competitive success
Relating plant traits and species distributions along bioclimatic gradients for 88 Leucadendron taxa
Effects of temperature on performance and phenotypic selection on plant traits in alpine Ranunculus acris
Discovering temperature effects on the performance of tundra plants is important in the light of expected climate change. In this 4-year study on alpine Ranunculus acris, I test the hypothesis that temperature influences flowering phenology, reproductive success, growth, population dynamics, and phenotypic selection on quantitative traits, by experimental warming using open-top chambers (OTCs). Warming significantly advanced flowering phenology in only one season. Seed number and weight were significantly increased by warming during the first three seasons, but not in the fourth. Plants inside OTCs produced bigger leaves than control plants in the fourth season, but leaf number was unaffected by the OTC treatment. Despite increased seed number and weight, the density of flowering plants decreased inside OTCs compared to control plots, possibly because of a higher graminoid cover inside OTCs. Phenotypic-selection regression showed a significant selection differential and gradient in the direction of larger leaf sizes in control plants, whereas no selection on leaf size was detected on warmed plants. The direction and strength of selection on flowering time, flower number, and leaf number did not differ between control and warmed plants. The results suggest that increased reproductive output of R. acris may not be sufficient to maintain current population density under a denser vegetation cover.
A quantitative analysis of leaf form in woody plants from the world's major broadleaved forest types
Leaf traits as indicators of resource-use strategy in floras with succulent species
Response of forest plant species to land-use change: a life-history trait-based approach
Simple traits do not predict grazing response in Australian dry shrublands and woodlands
Sprouting by semi-arid plants: testing the dichotomy and predictive traits
Comparison of leaf construction costs in woody species with differing leaf life-spans in contrasting ecosystems
Why is Solidago shortii narrowly endemic and S. altissimo geographically widespread?A comprehensive comparative study of biological traits
Plant functional types of zonal woody plant communities in relation to hydrothermic factors
Plant traits and soil chemical variables during a secondary vegetation succession in abandoned fields on the Loess Plateau
Plant traits and environmental condition along the Northeast China Transect (NECT)
Responses of plant functional types to an environmental gradient on the Northeast China Transect
Correlation analysis on the relationship between plant life form, fruit type and hydrothermic factors in Gansu woody plant flora
Photosynthetic pathways and life forms in different grassland types from North China
Photosynthetic pathway types of forage species along grazing gradient from the Songnen grassland, Northeastern China
Climate-driven changes in shoot density and shoot biomass in Leymus chinensis (Poaceae)on the Northeast China Transect (NECT)
Can comparative approaches based on plant ecophysiological traits predict the nature of biotic interactions and individual plant species effects in ecosystems?
A leaf-height-seed (LHS)plant ecology strategy scheme
Plant ecological strategies: some leading dimensions of variation between species
Estimation of mean annual temperature from leaf and wood physiognomy
Do life history traits affect the accuracy of diffusion approximations for mean time to extinction?
Specific leaf area and leaf dry matter content as alternative predictors of plant strategies
The worldwide leaf economics spectrum
Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.
Leaf traits relationships in Australian plant species
Leaf trait data were compiled for 258 Australian plant species from several habitat types dominated by woody perennials. Specific leaf area (SLA), photosynthetic capacity, dark respiration rate and leaf nitrogen (N) and phosphorus (P) concentrations were positively correlated with one another and negatively correlated with average leaf lifespan. These trait relationships were consistent with previous results from global datasets. Together, these traits form a spectrum of variation running from species with cheap but frequently replaced leaves to those with strategies more attuned to a nutrient-conserving lifestyle. Australian species tended to have SLAs at the lower end of the spectrum, as expected in a dataset dominated by sclerophyllous species from low fertility or low rainfall sites. The existence of broad-scale, 'global' relationships does not imply that the same trait relationships will always be observed in small datasets. In particular, the probability of observing concordant patterns depends on the range of trait variation in a dataset, which, itself, may vary with sample size or species-sampling properties such as the range of growth forms, plant functional 'types', or taxa included in a particular study. The considerable scatter seen in these broad-scale trait relationships may be associated with climate, physiology and phylogeny.
Differences in seedling growth behaviour among species: trait correlations across species, and trait shifts along nutrient compared to rainfall gradients
Nutrient concentration, resorption and lifespan: leaf traits of Australian sclerophyll species
Convergence towards higher leaf mass per area in dry and nutrient-poor habitats has different consequences for leaf life span
Response of seedlings of three dominant shrubs to climate warming in Ordos Plateau
Effect of different water conditions on growth and morphology of Artemisia ordosica Krasch
Geographic variation in nut size of Castanopsis species in Japan
Physioecological characteristics of Woonyoungia septentrionalis seedling under various soil water conditions
Advances in ecological studies on leaf lifespan and associated leaf traits
Responses to continual grazing of major functional types of Gramineae in Horqin sandy grassland, Inner Mongolia
