鼎湖山季风常绿阔叶林两种优势树种的生境适应研究:叶片功能性状和水力结构特征

Habitat adaptation of two dominant tree species in a subtropical monsoon forest: leaf functional traits and hydraulic properties

植物在长期的进化和发展过程中,通过与环境相互作用形成了适应环境的形态结构及生理特征,反映了植物适应环境的生态策略;在森林群落中,地形和土壤等的变异常导致生境的异质性,从而直接或者间接影响物种的分布格局。因此,在生境异质性较强的森林群落中,植物物种分布格局与其生态适应策略有何关系,是值得关注的问题。该文以鼎湖山南亚热带季风常绿阔叶林20 hm2监测样地为平台,针对两种常绿优势树种罗伞树(Ardisia quinquegona)和光叶山黄皮(Aidia canthioides),对比研究了两种植物的叶片功能性状和水力结构特征在山脊、山坡、山谷三种不同生境中的生态适应策略,以阐明物种分布格局与其生态适应策略的关系。结果表明:罗伞树主要是通过调整叶面积(LA)、木材密度(WD)及渗透调节来适应不同生境;光叶山黄皮主要通过调整比叶面积(SLA)、WD及渗透调节,采取养分有效保存(低SLA,高干物质含量)及慢生长高存活的策略以适应不同生境,适应环境能力更强,尤其是在山脊和山坡生境;而且影响两个树种叶片功能性状和水力结构的主导土壤因子有所不同。研究结果说明罗伞树和光叶山黄皮对山脊和山坡生境比山谷更为适应,但在叶片功能性状和水力结构特征方面的生境适应策略不同。

During the long-term processes of evolution and development,plant species yield a set of morphological, structural and physiological characteristics through their interactions with the environment,and these characteristics indicate their ecological adaptive strategies to the environment.Within forest communities,topographic and edaphic variations often lead to habitat heterogeneity,and hence tend to directly or undirectly influence the distribution pat-terns of plant species.Thus,it is an important question that how plant species distribution is related to its ecological adaptive strategies in forest commnuties with high habitat heterogeneity.Ardisia quinquegona and aldia canthioides are two dominant evergreen tree species in the subtropical monsoon evergreen broad-leaved forest within the 20 ha forest biodiversity monitoring plot at Dinghushan National Nature Reserve in Zhaoqing City,Guangdong Province, China.The two tree species are distributed in different habitats including mountaln ridge,slope,and valley.To under-stand the relation of their ecological strategies of habitat adaptation to their distribution patterns in the forest,a com-parative study was conducted on their leaf functional tralts and hydraulic properties among the three different habitats. Functional tralts measured include leaf area （LA）,leaf thickness,leaf length/leaf width ratio,specific leaf area （SLA）,and leaf dry matter content （LDMC）,while hydraulic properties include sapwood specific hydraulic conduc-tivity,leaf specific conductivity,huber value,wood density （WD）,leaf water potential at turgor loss point （π0 ）and saturated leaf water potential （π100 ）.The results showed that A .quinquegona tended to adapt to different habitats malnly through the adjustment of leaf area LA,WD and osmotic regulation.In contrast to A .quinquegona ,A .can-thioides had a stronger ability to adapt to the environment,especially mountaln ridge and slope habitats,via the strate-gy of “slow growth rate and high survival rate”.It malnly made fine adjustment on SLA,WD and osmotic regulation, and used the strategy of efficient conservation of nutrients （low SLA,high LDMC）.Moreover,the soil factors that limit leaf functional tralts and plant hydraulics differed between the two studied tree species.Our results revealed that both species were suitable to survive in mount ridge and slope rather than in valley,while they differed in habitat ad-aptation strategies regarding leaf functional tralts and hydraulic properties,although they both were dominant species in the subtropical monsoon evergreen broad-leaved forest.