Establishing a Multi-Century, Annual-Resolution Climate Record from the Northeastern Caribbean

在中高纬度地区，树木年代学提供了一些最有价值的年度分辨率气候记录，其中大多数显著地将我们的气候知识扩展到仪器记录之前的时间。相比之下，来自低纬度地区的树木气候学记录很少，因为热带树木很少产生可靠的年轮，使树木年代学研究成为可能。这个研究项目建立在一个发现的基础上，即加勒比海伊斯帕尼奥拉岛的本土松树西松（Pinus occidentalis Swartz）产生了对水分敏感的优秀年轮。这个物种提供了一个有价值的代用降水记录，但只有当它生长在海拔最高和湿度紧张的地区时，在海拔3000米左右，在稳定的块地和悬崖上。调查人员从120个标本中收集了木材样本（岩心和一些活树的部分，加上死树和残木的部分）。对小子集的初步研究显示出了很大的潜力。该奖项支持对这些样品进行分析，方法包括表面处理、计算机测量放大后的年轮、对年表进行统计分析，包括与现代气候数据进行比较。在取样的林分中有大量的火痕，我们将分析该物种的火响应，以评估该物种为这些加勒比高地提供亚季节性火灾历史信息的潜力。在林间受火保护的裸露岩石中发现了罕见的亚化石残木碎片，研究人员将试图利用放射性碳定年法，从这些样本中确定漂浮年表的年龄分布，以估计这些地点和类似地点的最终潜在记录长度。最后，该奖项将用于资助田纳西大学树木年轮科学实验室正在进行的改善公众宣传活动的努力。这些努力包括帮助学生和其他人发现树木年轮研究的乐趣。这个项目的重要性源于这样一个事实，即西松生长在热带纬度地区，该地区没有像温带地区那样见证了基于树木年轮的气候记录的发展。在地理方面，最近的已发表的树木气候学记录是在西北1700公里外的热带地区。随着人们对气候和气候变化对人类社会重要性的认识不断提高，对热带气候动力学的科学理解也在不断增长。该项目将提供热带地区降水的第一个陆地代用记录，该地区在气候方面与北美大陆密切相关。它还将加强教育工作，使学生和公众了解树木年轮研究的过程和结果。

At middle and high latitudes, dendrochronology has provided some of the most valuable annual-resolution climate records available, most of which significantly extend our knowledge of climate back into time well before periods with instrumental records. In contrast, few dendroclimatological records from low latitudes exist, because tropical trees rarely produce reliable annual rings that allow dendrochronological research. This research project builds on the finding that Pinus occidentalis Swartz, the native pine of the Caribbean island of Hispaniola, produces excellent rings that are moisture-sensitive. This species provides a valuable proxy precipitation record, but only when it grows at the very highest-elevation and moisture-stressed sites within its range, near 3,000 meters in elevation, in stabilized blockfields, and on cliffs. The investigators have collected wood samples (cores and a few sections of living trees, plus sections of dead trees and remnant wood) from 120 specimens. Initial work on small subsets shows promising potential. This award supports analyses of these samples through surface preparation, computer-measurement of rings under magnification, and statistical analysis of the chronologies including comparison with modern climate data. Fire scars are abundant in the stands sampled, and the species' fire response will be analyzed to assess the potential of the species to yield sub-seasonal fire history information for these Caribbean highlands. Rare pieces of subfossil remnant wood are found in fire-protected bare-rock spots within the stands, and the investigators will try to determine the age distributions of floating chronologies from such specimens using radiocarbon dating in order to estimate the ultimate potential record length from these and similar sites. Finally, the award will help fund ongoing efforts to improve public-outreach activities at the University of Tennessee's Laboratory of Tree-Ring Science. These efforts include helping school children and others discover the excitement of tree-ring research.The importance of this project stems from the fact that Pinus occidentalis grows at tropical latitudes, a region that has not witnessed the development of tree-ring-based climate records as have more temperate locales. In geographic terms, the nearest published dendroclimatological record is 1,700 kilometers to the northwest in an extra-tropical location. As awareness of the importance to human society of climate and climate change increases, the scientific impetus to improve understanding of tropical climate dynamics continues to grow. This project will provide the first terrestrial proxy record of precipitation from a tropical region that is closely connected in climatic terms to the North American mainland. It also will enhance educational efforts to inform students and the public about the processes and outcomes of tree-ring research.