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

9510015雅各布斯这项拟议的研究旨在确定赤道非洲现代叶形与气候之间的统计关系，并由此估计肯尼亚中新世中晚期(14至5 Ma)叶组合的古气候。为了实现这些目标，将对非洲30个活着的植物群落的植物标本表进行录像，并将使用Optimas分析树叶图像。关于叶面积、长度、宽度、周长和边缘的信息将被记录下来(完整或不完整，是否有复合齿，是否有滴头)。从已公布的来源、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使用GSMAP和相关工具在非洲底图上绘制成等高线。每个厂址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站的记录来检查内插。将根据变量之间的分布和关系，通过适当的统计方法对树叶和气候数据进行分析。例如，用于非线性数据的多变量方法，如对应分析和典型对应分析，可能是合适的。由此产生的统计关系将被校准。通过将校准应用于分析中未包括的现代站点，将对校准的准确性进行测试。如果准确估计现代组合的气候参数，则可以利用该技术重建中新世叶片组合的气候。中新世中期至中新世晚期是一个重要的时间间隔，因为人类大家庭在此期间起源于非洲。此外，现代大气环流模式，最重要的是亚洲季风，被认为起源于中新世(Quade等人，1989；Prell等人，1992)。季风环流在一定程度上导致了现代植物群落的分布，包括稀树草原和草原。这些生物群的起源，可能与季风的起源和原始人的起源一致，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续分布的假设表明，中新世中期连续森林的碎片化是一个原因(Lovett，1993)。这一时期的古植物学记录为这些假说提供了直接的检验。此外，大多数赤道植物物种的化石记录都很差。古植物学遗址的研究提供了一个机会，为研究现存植物区系的系统发育关系和生物地理历史做出贡献。

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.