A Retrospective Dendroecology of American Chestnut in the Southern Appalachian Forest

9509307 Stahle灾难性的栗疫病摧毁了东部落叶林最重要的物种之一，并引发了可能持续几个世纪的动态森林反应。由于缺乏关于枯萎前森林的定量数据，了解枯萎病对环境的影响的努力变得复杂。幸运的是，在一些选定的森林中，板栗生长的准确和详细的记录仍然可以从枯萎病杀死的日志中恢复，否则很大程度上不受干扰。该项目将开发200至300年的美国板栗树轮年表从枯萎病杀死日志在南部阿巴拉契亚地区的六个古老的森林位置。还将在同一地点为铁杉和橡树的三个年龄类别编制树木年轮年表。这三类将是古老的，年轻的枯萎病前，年轻的枯萎病后的树木。至少有24个年表将开发，包括3个板栗和9个橡树从干旱的网站。在可能的情况下，将利用从早期历史建筑中恢复的古栗木来延长栗木年表。所有年表将与早在1871年开始的月度气候数据进行比较，以确定板栗在枯萎前森林中的气候反应，以及其在枯萎前和枯萎后森林中的两个重要的前伙伴。年表将被用来测试假设可能的变化，在南部阿巴拉契亚森林生态系统的气候迫使枯萎病。PI将测试板栗的成熟生长速率受到板栗特有的特定气候变量限制的假设。如果是真的，这种独特的气候影响的一个重要部分的定居森林已大大减少了选择性删除板栗。他们还将检验这样的假设：枯萎病引发的小气候变化已经改变了最限制铁杉和橡树等栗子伴生植物生长的特定季节气候变量。提出的树木年轮年表将挽救一个无价的板栗生长记录，它被忽视了50多年，可能很快就会腐烂而无法恢复。

9509307 Stahle The catastrophic chestnut blight destroyed one of the most important species of the eastern deciduous forest and initiated dynamic forest responses that may last for centuries. The scarcity of quantitative data on pre-blight forests has complicated efforts to understand the environmental impact of the blight. Fortunately, an exact and detailed record of chestnut growth can still be recovered from blight-killed logs in a few selected forests that are otherwise largely undisturbed. This project will develop 200- to 300-year long tree-ring chronologies of American Chestnut from blight killed logs at six ancient forest locations in the southern Appalachian region. Tree-ring chronologies will also be developed at the same locations for three age categories of hemlock, and oak. These three categories will be ancient, young pre-blight, and young post-blight trees. At least 24 chronologies will be developed, including 3 chestnut and nine oak from xeric sites. The chestnut chronologies will be extended when possible with ancient chestnut timbers recovered from early historic buildings. All chronologies will be compared with monthly climate data which begin as early as 1871 in order to define the climate response of chestnut in pre-blight forests, and two of its important former associates in pre- and post-blight forests. The chronologies will be used to test hypotheses concerning possible changes in the climate forcing of southern Appalachian forest ecosystems following the blight. The PIs will test the hypothesis that the mature growth rates of chestnut were limited by specific climate variables unique to chestnut. If true, this unique climate influence on an important fraction of presettlement forests has been greatly diminished by the selective removal of chestnut. They will also test the hypothesis that the microclimate changes initiated by the blight have altered the specific seasonal climate variables most limiting to the growth of chestnut associates such as hemlock and oak. The p roposed tree-ring chronologies will salvage a priceless record of chestnut growth that has been ignored for over 50 years and may soon decay beyond recovery.