A Foliar Geographic Study of Leaf Water Repellency as an Adaptation to Cloud Forest Environments

叶片拒水性适应云林环境的叶地理学研究

• 批准号: 0452103
• 负责人: Curtis Holder
• 金额: $ 6.5万
• 依托单位: University of Colorado at Colorado Springs
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0452103&HistoricalAwards=false
• 关键词: Foliar; Geographic; Study; Leaf; Water

Fog persistency contributes to the unique biogeography and hydrology of tropical montane cloud forests. The presence of fog droplets on leaf surfaces may inhibit photosynthetic carbon exchange. Previous studies have reported that carbon dioxide diffuses approximately 10,000 times slower in water than air. The beading of water on leaf surfaces enables the maintenance of high photosynthetic rates. In cloud forest environments with a high persistency of fog, increased leaf water repellency may be a selective strategy to promote photosynthetic efficiency during cloudy periods. The significance of leaf characteristics such as leaf water repellency as a mechanism that influences hydrological processes is an unexplored research topic in geography and hydrology. Information on the interaction between the physical properties of the leaf surface and fog or water droplets on the leaf surface is useful to develop enhanced models of cloud forest hydrological processes that investigate throughfall, stemflow, and fog precipitation totals. Species with highly repellent leaf surfaces may increase the quantities of throughfall, stemflow, and fog precipitation at a site and may result in greater hydrological inputs beneath the cloud forest canopy. This comparative foliar geography study will examine leaf water repellency of 24 dominant species in cloud forests of the Sierra de las Minas Biosphere Reserve and in lowland forests near the community of San Jose La Arada, Guatemala. Leaf water repellency is measured by calculating the contact angle between a water droplet and the leaf surface. A greater contact angle indicates a more spherical water droplet and a more water-repelling surface. The investigator and two students will measure leaf water repellency and will collect data on leaf characteristics (leaf area, leaf thickness, leaf mass, specific leaf mass, specific leaf area, leaf toughness, stomatal density, trichome density, presences of epiphylls, and evidence of herbivore and pathogen damage) of each species. The objective of this project is to examine whether tropical cloud forest species have a higher degree of leaf water repellency than lowland tropical species. Furthermore, this project will identify leaf characteristics that contribute to leaf water repellency. Knowledge of hydrological processes within cloud forests can be used to guide environmental policy on the management of these endangered ecosystems. Defining the spatial patterns of leaf water repellency between different habitats and species is an important missing link in hydrological research. With clearer understanding of the differences between leaf water repellency among dominant species at a site and between sites, more meaningful models of forest hydrology processes can be formulated that incorporate leaf surface variables. Furthermore, this study will provide a basis for exploring the potential hydrologic impact of land use changes that result from changes in leaf characteristics. The hydrological inputs in cloud forests and an understanding of the hydrological processes that increase water resource availability from the cloud forests are vital to the livelihood of people in the arid lowland regions of Guatemala.

雾的持久性有助于热带山地云雾林独特的地理和水文。 叶片表面雾滴的存在可能会抑制光合碳交换。 以前的研究报告说，二氧化碳在水中的扩散速度比空气慢大约10，000倍。 叶片表面的水珠使光合作用的速率保持在较高水平。 在云雾森林环境中，高persistance的雾，增加叶片的拒水性可能是一种选择性的策略，以促进光合效率在多云期间。 叶片的特征，如叶片的斥水性作为一种机制，影响水文过程的意义是一个尚未探索的研究课题，在地理和水文。 叶表面的物理特性和雾或水滴的叶表面之间的相互作用的信息是有用的云雾森林水文过程，调查穿透，茎流和雾降水总量的增强模型。 具有高度排斥性的叶表面的物种可能会增加穿透雨，茎流和雾降水的数量在一个网站，并可能导致更大的水文输入下的云雾林冠层。 这种比较叶面地理学研究将探讨24个主要物种的叶片斥水性在云雾森林的Sierra de las Minas生物圈保护区和低地森林附近的社区圣何塞拉阿拉达，危地马拉。 通过计算水滴与叶表面之间的接触角来测量叶的防水性。 接触角越大，表明水滴越球形，表面越防水。 研究人员和两名学生将测量叶片的防水性，并收集每个物种的叶片特征（叶面积，叶厚度，叶质量，比叶质量，比叶面积，叶韧性，气孔密度，毛状体密度，存在的Epiphylls，以及草食动物和病原体损害的证据）的数据。 本计画的目的是研究热带云雾林物种是否比低地热带物种具有更高程度的叶片防水性。 此外，该项目将确定有助于叶片防水性的叶片特征。 云雾森林内水文过程的知识可用于指导管理这些濒危生态系统的环境政策。 确定不同生境和物种间叶片斥水性的空间格局是水文学研究中重要的缺失环节。 随着更清楚地了解叶的水排斥性之间的差异，在一个网站和网站之间的优势物种，更有意义的森林水文过程模型，可以制定纳入叶表面变量。 此外，这项研究将为探索叶子特征变化导致的土地利用变化的潜在水文影响提供基础。 云雾林的水文输入和对增加云雾林水资源可用性的水文过程的了解，对危地马拉干旱低地地区人民的生计至关重要。