Production and Resource Use Efficiency of Larch and Sympatric Evergreen Conifers

落叶松是一种落叶针叶树，盛产于整个北半球的高山、亚高山和北方森林中。落叶松在寒温带山地和北方落叶林中的广泛重要性，以及与常绿针叶树相似的冠层结构、针叶形态和导水系统，使落叶松成为阐明叶片习性(如常绿与落叶)对碳平衡和养分利用影响的理想物种。主要研究人员建议对比蒙大拿州高山森林中的西方落叶松和短尾松，以及威斯康星州北方森林中的落叶松和云杉的碳和养分利用情况。主要假设如下：(1)落叶松的地上净初级生产力等于或大于同地常绿针叶树；(2)落叶松和同地常绿针叶树的总(地上和地下)净初级生产力相似，因为落叶松的地下净初级生产力小于常绿针叶树。最后，他们推测(4)落叶松比常绿针叶树更有效地利用氮素(叶、树冠和林分水平)。这些假说导致了几个推论假说，预测了使落叶松成功完成常绿针叶树的生理和结构特征的作用。

Larix, a deciduous conifer, is abundant in high montane, subalpine, and boreal forests throughout the Northern Hemisphere. The widespread importance of larch in cold-temperate montane and boreal forests and its similar canopy architecture needle morphology and water conducting system to evergreen conifers makes larch an ideal species to elucidate the influence of leaf habit (e.g., evergreen vs. deciduous) on carbon balance and nutrient use. The principal investigators propose to contrast the carbon and nutrient use of Larix occidentals and Pinus contorta in high montane forests in Montana and Larix laricina and Picea mariana in boreal forests in Wisconsin. The major hypotheses are: (1) aboveground net primary production is equal or greater for larch than sympatric evergreen conifers, (2) total (above-and belowground) net primary production is similar for larch and sympatric evergreen conifers because (3) belowground net primary production in larch is less than in evergreen conifers. Lastly, they speculate (4) larch uses nitrogen more efficiently (leaf, canopy, and stand-level) than evergreen conifers. These hypotheses lead to several corollary hypotheses predicting the role of physiological and architectural traits that enable larch to successfully complete with evergreen conifers.