(ESH) The Interpretation of Climate from Leaf Forms: Application to the Miocene of Africa

(ESH) 从叶子形态解释气候：应用于非洲中新世

• 批准号: 9510015
• 负责人: Bonnie Jacobs
• 金额: $ 4.15万
• 依托单位: Southern Methodist University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-15 至 1997-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9510015&HistoricalAwards=false
• 关键词: ESH; Interpretation; Climate; Leaf; Forms

9510015 Jacobs The proposed research aims to define the statistical relationships between modern leaf form and climate in equatorial Africa, and from them, to estimate paleoclimate for middle to late Miocene (14 to 5 Ma) leaf assemblages from Kenya. To achieve these goals, herbarium sheets of species from 30 living plant communities across Africa will be videotaped and leaf images will be analyzed using Optimas. Information on leaf area, length, breadth, perimeter, and margin (entire or not, presence or absence of compound teeth, presence or absence of drip tip) will be recorded. Monthly climate data obtained from published sources, the U.S. Data Center, and the Ulited Nations Environmental Program Global Resource Information Database (GRID) will be mapped as contours on a base map of Africa using GSMAP and related utilities. Climate data for each plant site will be read from the map and interpolations will be checked by consulting local station records where possible. The leaf and climate data will be analyzed by appropriate statistical methods depending upon distributions and relationships among the variables. For example, multivariate methods such as correspondence analysis and canonical correspondence analysis, which are intended for nonlinear data, may be appropriate. The resulting statistical relationships will be calibrated. The calibration will be tested for accuracy by applying it to modern sites not included in the analysis. If climatic parameters of modern assemblages are estimated accurately, then the technique can be used to reconstruct climate for Miocene leaf assemblages. The middle to late Miocene is a significant time interval because the human family originated in Africa during that time. Further, modern atmospheric circulation patterns, most importantly the Asian monsoon, are thought to have originated in the Miocene (Quade et al., 1989; Prell et al., 1992). Monsoonal circulation is, in part, responsible for the distribution of modern plant communities, including savannas and grasslands. The origin of these biomes, perhaps coincident with the origin of the monsoons and the origin of hominids, remains a controversial subject (Retallack, 1992; Cerling et al., 1991; Kingston et al, 1994; Wheeler, 1991; Lovejoy, 1981). Similarly, hypotheses that explain disjunct distributions of modern forest species in East and West Africa suggest fragmentation of middle Miocene continuous forest as a causal factor (Lovett, 1993). The paleobotanical record for this time period offers a direct test for these hypotheses. In addition, the fossil record of most equatorial plant species is poor. The study of paleobotanical sites offers an opportunity to make contributions regarding phylogenetic relationships and biogeographic history of the living flora.

该研究旨在确定赤道非洲现代叶片形态与气候之间的统计关系，并以此估计肯尼亚中新世中期至晚期（14至5 Ma）叶片组合的古气候。为了实现这些目标，将对非洲30个现存植物群落的植物标本进行录像，并使用Optimas分析叶片图像。记录叶面积、长度、宽度、周长和边缘（完整或不完整，有无复合齿，有无滴头）的信息。利用GSMAP和相关工具，从公开来源、美国数据中心和联合国环境规划署全球资源信息数据库（GRID）获得的月度气候数据将以等高线的形式绘制在非洲基础地图上。每个厂区的气候数据将从地图上读取，并在可能的情况下通过查阅当地台站记录来检查插值。树叶和气候数据将根据变量之间的分布和关系，用适当的统计方法进行分析。例如，用于非线性数据的多变量方法（如对应分析和规范对应分析）可能是合适的。由此产生的统计关系将被校准。将校正应用于分析中未包括的现代地点，以检验其准确性。如果现代组合的气候参数估算准确，那么该技术可以用于重建中新世叶片组合的气候。中新世中期到晚期是一个重要的时间间隔，因为人类家族在那个时期起源于非洲。此外，现代大气环流模式，尤其是亚洲季风，被认为起源于中新世（Quade et al., 1989; Prell et al., 1992）。在一定程度上，季风环流对包括热带稀树草原和草原在内的现代植物群落的分布负有责任。这些生物群落的起源，可能与季风的起源和原始人类的起源一致，仍然是一个有争议的话题（Retallack, 1992； Cerling等人，1991；Kingston等人，1994;Wheeler, 1991; Lovejoy, 1981）。同样，解释东非和西非现代森林物种不连贯分布的假设表明中新世中期连续森林的破碎化是一个原因（Lovett, 1993）。这一时期的古植物学记录为这些假设提供了直接的检验。此外，大多数赤道植物物种的化石记录很差。对古植物遗址的研究为研究现存植物的系统发育关系和生物地理历史提供了机会。