两种热带木质藤本幼苗形态、生长和光合能力对光强和养分的响应

比较了两种不同攀援习性，卷须缠绕种薄叶羊蹄甲（Bauhinia tenuiflora）和茎缠绕种刺果藤（Byttneria aspera），木质藤本植物的形态、生长及光合特性对不同光强（4％、35％和全光照）和土壤养分（高和低）的响应。两种藤本植物大部分表型特征主要受光照的影响，而受土壤养分的影响较小。弱光促进地上部分生长，弱光下两种植物均具有较大的比叶面积（specific leaf area，SLA）、茎生物量比（stem mass ratio，SMR）和平均叶面积比（mean leaf area ratio，LARm）。高光强下，两种植物的总生物量和投入到地下部分的比重增加，具有更大的根生物量比（root mass ratio，RMR）、更多的分枝数、更高的光合能力（maximum photosynthetic rate，Pmax）和净同化速率（net assimilation rate，NAR），综合表现为相对生长速率（relative growth rate，RGR）增加。两种藤本植物的Pmax与叶片含氮量的相关性均未达显著水平，但刺果藤的Pmax与SU志间呈显著的正相关，而薄叶羊蹄甲的Pmax与SLA之间相关性不显著。在相同光照强度和土壤养分条件下，卷须缠绕种薄叶羊蹄甲的RGR显著高于茎缠绕种刺果藤。薄叶羊蹄甲的RGR与NAR呈显著正相关，其RGR与SLA、平均叶面积比（EARm）及Pmax之间相关性不显著。刺果藤的RGR与NAR呈显著的正相关，而与SLA存在显著的负相关。上述结果表明，与土壤养分相比，光照强度可能是决定木质藤本分布更为重要的生态因子。卷须缠绕种薄叶羊蹄甲由于具有特化的攀援器官，在形态上和生理上具有更大的可塑性，这使得卷须缠绕种木质藤本在与其它植物的竞争中更具优势。

Morphological, Growth and Photosynthetic Traits of Two Liana Species in Response to Different Light and Soil Nutrients

The present study explored the morphological, growth and photosynthetic traits of seedlings of two liana species with different climbing mechanisms -- Bauhinia tenuiflora, a tendril-climbing species; and Byttneria aspera, a stem-climbing species -- grown at three irradiances （4%, 35% and 100% sunlight） and low and high soil nutrient levels. Irradiance significantly affected most of the 15 phenotypic traits of the two species; however, soil nutrient affected only a few phenotypic traits. Seedlings grown under low light showed higher and more biomass investment into aboveground growth. Specific leaf area （SLA）, stem mass ratio （SMR） and mean leaf area ratio （LARm） of the seedlings decreased with irradiance, under which they had higher root mass ratio （RMR） in order to improve the ability of absorption. Meanwhile, the ability for light capturing was improved by increased branch numbers. Relative growth rate （RGR）, maximum photosynthetic rate （Pmax） and net assimilation rate （NAR） increased with high irradiance. When the two species were grown under the same conditions, B. tenuiflora often showed significantly higher RGR than B. aspera. Pmax was positively correlated with SLA for B. tenuiflora, and NAR but not SLA, I-ARm or Pmax was positively correlated with RGR for B. tenuiflora. In B. aspera, NAR was positively correlated with RGR, whereas SLA was negatively correlated with RGR. B. tenuiflora showed higher physio- and morphological plasticity in response to light and soil nutrient gradient than B. aspera. In conclusion, light is a critical factor in the distribution of lianas. With the specialized climbing tissues, B. tenuiflora might have wider distribution than B. aspera because of its higher phenotypic plasticity.