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.
