Relative humidity has dramatic impacts on leaf morphology but little effect on stomatal index or density in Nothofagus cunninghamii (Nothofagaceae)
Relative humidity has dramatic impacts on leaf morphology but little effect on stomatal index or density in Nothofagus cunninghamii (Nothofagaceae)
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DOI：
10.1071/bt12110
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发表时间：
2012-01-01
影响因子：
1.1
通讯作者：
Osanai, Yui
中科院分区：
文献类型：
--
作者：
Hovenden, Mark J.;Vander Schoor, Jacqueline K.;Osanai, Yui
利用基于化石和亚化石叶片的代用物重建过去的环境条件是困难的，因为叶片的形态受到许多相互作用的环境因素的影响，如温度、二氧化碳浓度、光照、土壤水分有效性以及潜在的大气相对湿度（RH）。本研究以南方山毛榉（Nothofagus cunninghamii）作为古环境重建的重要树种，在温室实验中测试了50% RH差异对其叶片形态和表皮解剖结构的影响。叶片的大小、形状和厚度均受RH的强烈影响，无论植株接穗大小，高湿叶片都比低湿叶片更大、更窄、更厚。RH对表皮性状的影响一般较小，且依赖于果实的加入。特别是，表皮细胞大小在不同的品种和RH水平上非常一致。因此，杉木叶片的总形态对RH的变化较为敏感，而表皮性状对RH的变化不敏感。因此，如果研究了足够数量的叶片，该物种表皮的古环境信号不太可能受到RH变化的影响。然而，毛叶形态与RH密切相关，如果RH可能发生变化，则不应用于古气候重建。
Reconstructing past environmental conditions using proxies based on fossil and subfossil leaves is difficult because leaf form is influenced by many interacting environmental factors such as temperature, CO2 concentration, light, soil water availability and, potentially, atmospheric relative humidity (RH). We used a species important for palaeoenvironmental reconstruction, the southern beech, Nothofagus cunninghamii, to test for the effects of a 50% difference in RH on leaf morphology and epidermal anatomy in a glasshouse experiment. Leaf size, shape and thickness were all strongly affected by RH with leaves from high humidity being larger, narrower and thicker than those from low humidity regardless of plant accession. RH impacts on epidermal characters were generally slight and dependent upon accession. In particular, epidermal cell size was remarkably consistent across accessions and RH levels. Thus, gross leaf morphology of N. cunninghamii was sensitive to changes in RH but, on average, epidermal characters were not. Thus, palaeoenvironmental signals from the epidermis of this species are unlikely to be affected by variation in RH, provided sufficient numbers of leaves are investigated. Gross leaf morphology, however, was strongly related to RH and should not be used for palaeo-climatic reconstruction if changes in RH are likely.