Page 66 - 《广西植物》2020年第3期
P. 66

3 4 6                                 广  西  植  物                                         40 卷
       Abstract: Mangrove species are a group of treesꎬ shrubs or herbs that grow in tropical and subtropical intertidal
       zones. They are usually divided into true mangrove and semi ̄mangrove speices according to their distributionꎻ the former
       is confined to intertidal zones with relatively high salinityꎬ but the latter can grow in both intertidal and upland zones. In ̄
       tertidal zones are generally characterized by high salinityꎬ high sunlight and hypoxia. In such hostile environmentsꎬ how
       true mangrove and semi ̄mangrove speices differ in their ecological adaptation strategies has not been well elucidated. In
       order to explore the differences of ecological adaptation strategies of true mangrove and semi ̄mangrove speices on high
       salinityꎬ high light and hypoxia in intertidal zonesꎬ we compared the leaf anatomical and functional traits of five true
       mangrove and four semi ̄mangrove speices that were widely distributed in south subtropical zones. We selected the five
       true mangrove species (Acrostichum aureumꎬ Aegiceras corniculatumꎬ Acanthus ilicifoliusꎬ Bruguiera gymnorr ̄hizaꎬ Kan ̄
       delia candel) and the four semi ̄mangrove speices (Heritiera littoralisꎬ Hibiscus tiliaceusꎬ Pongamia pinnataꎬ Thespesia
       populnea) at Mangrove Natural Reserve of Qi’ao Island of Zhuhai Cityꎬ Guangdong Provinceꎬ China. We observed leaf
       anatomical structures including leaf epidermis and ancillary structureꎬ hypodermisꎬ palisade tissueꎬ spongy tissue and
       stomataꎬ and then measured stomatal density and leaf thickness under a JSM ̄6360LV scanning electron microscope. We
       measured leaf functional traits including specific leaf areaꎬ leaf mass per areaꎬ leaf water contentꎬ and leaf fresh/ dry
       weight ratio according to a published standar ̄dized protocol. The results were as follows: (1) Leaves of all the nine man ̄
       grove species had common anatomical characteristics such as epidermis covered by horny layersꎬ palisade and spongy tis ̄
       sues that differentiated in the mesophyllꎬ and sunken stomata. (2) Leaves of the true mangrove species had waxy layers
       and hypodermisꎬ but had no foliar trichomesꎬ and their stomata were only distributed in the lower epidermisꎻ howeverꎬ
       leaves of semi ̄mangrove speices had less wax layersꎬ some of them had foliar trichomes but no hypodermisꎬ and distribu ̄
       tion of stomata in either upper or lower epidermis was not consistent. (3) Stomatal density and specific leaf area of true
       mangrove species were significantly lower than those of semi ̄mangrove speices (P<0.05)ꎬ while leaf thicknessꎬ leaf
       water contentꎬ specific leaf mass and leaf fresh/ dry weight ratio were significantly higher than those of semi ̄mangrove
       speices (P<0.05). These results indicate that leaves of true mangrove species have more advantages in maintaining sa ̄
       linity balance and water conservation than semi ̄mangrove speicesꎬ and thus can better adapt to high salinity in intertidal
       environments.
       Key words: mangrove plant speciesꎬ true mangrove speciesꎬ semi ̄mangrove speicesꎬ anatomical featuresꎬ functional
       traitsꎬ ecological adaptation

       红树植物是生长在热带、亚热带海岸潮间带                           的木栓瘤及皮孔排水器和盐腺(黄桂玲和黄庆昌ꎬ
   的乔木、灌木或草本植物ꎬ根据其分布特征通常分                            1989ꎻ李芳兰和包维楷等ꎬ2005ꎻ李元跃ꎬ2006ꎻ陈燕
   为真红树植物植物( true mangrove species) 和半红              等ꎬ2014)ꎮ 为了应对高盐环境ꎬ部分红树植物甚至
   树 植 物 ( semi ̄mangrove speices ) ( Tansley &       具有特化的小而厚的叶片ꎬ表现出肉质化的特征ꎬ如
   Fritschꎬ1905ꎻ林鹏ꎬ1987)ꎮ 真红树植物是指只生                  木果楝属( Xylocarpus)、拉关木属( Laguncularia) 和
   长在海岸潮间带的红树植物ꎬ半红树植物则是既                             水芫花属(Pemphis)ꎮ 有的分化出泌盐的盐腺ꎬ直接
   可以生长在潮间带又可以生长在内陆非盐碱地的                             排出盐分ꎬ如桐花树和老鼠簕(Sobradoꎬ 2005)ꎮ
   两栖类植物(Wangꎬ1987)ꎮ 红树植物长期适应于                           目前ꎬ针对红树植物叶片性状的研究主要集
   周期性的海水浸淹、土壤盐渍化、高盐度、缺氧和                            中于共同适应特征的描述ꎬ而对于两者叶片形态
   不稳 定 的 海 岸 环 境 ( 林 鹏ꎬ 1997ꎻ Zhong et al.ꎬ         解剖和功能性状的对比研究较少ꎮ 真红树植物和
   2002)ꎬ在形态、结构与繁殖特性上常表现出特殊                          半红树植物由于适应海水盐度不同ꎬ特化而成的
   的适应机制(李元跃ꎬ2006)ꎮ 例如ꎬ在形态解剖方                        形态结构也不同ꎬ如真红树植物适应高盐环境形
                                                                                          –
   面ꎬ红树植物叶片表现出旱生叶的构造特点( 林                            成内皮层( 陈健辉等ꎬ2018)ꎬ叶片的 Cl 、肉质化
   鹏ꎬ1997):具有较小的表皮细胞和内皮层结构ꎬ气                         程度和氮含量远高于半红树植物ꎬ而比叶面积则
   孔通常只分布于下表皮、下陷ꎬ叶片和角质层通常                            小于半红树植物ꎬ且水分利用效率和耐盐性及耐
   较厚ꎬ气孔密度较高ꎬ栅栏组织和中脉维管束发                             旱能力比半红树植物强(牟美蓉ꎬ2007)ꎮ 然而ꎬ已
   达ꎬ富含单宁ꎬ且大多数红树植物具有木栓层产生                            有研究涉及的红树种类不多ꎬ且较少同时考虑功
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