Kloeppel Brian D, Gower Stith T, Treichel Isabel W, Kharuk Slava
Department of Forest Ecology and Management, 1630 Linden Drive, University of Wisconsin - Madison, Madison, WI 53706, USA, , , , , , US.
Department of Chemistry, 1101 University Avenue, University of Wisconsin - Madison, Madison, WI 53706, USA, , , , , , US.
Oecologia. 1998 Apr;114(2):153-159. doi: 10.1007/s004420050431.
Larches (Larix spp.), deciduous conifers, occur in the northern hemisphere in cold-temperate and boreal climates - an environment normally thought to favor evergreen tree species. We compare foliar carbon isotope discrimination (Δ), instantaneous water use efficiency, total foliar nitrogen concentration, and specific leaf area (for a subset of sites) between Larix spp. and co-occurring evergreen conifers at 20 sites throughout the natural range of larches. Except for Larix occidentalis in the xeric Intermountain West, USA, Δ is significantly (P < 0.05) greater for larches than co-occurring evergreen conifers at 77% of the sites, suggesting that larches use water less efficiently. At elevations greater than 3000 m, the Δ of Larix spp. and co-occurring conifers converge, suggesting that water is not the limiting resource. Foliar nitrogen concentration and specific leaf area are two ecophysiological characteristics that are positively correlated with high photosynthetic capacity. Foliar nitrogen concentration is significantly greater for larches than evergreen conifers at 88% of the sites and specific leaf area is approximately three times greater for larches than co-occurring conifers. Future studies should examine the potential effect that global warming may have on the distribution of larch forests because the water use efficiency of larches is commonly less than co-occurring evergreen conifers and the boreal and high-latitude environments are likely to experience the greatest climate warming.
落叶松（落叶松属）是落叶针叶树，生长于北半球的寒温带和寒带气候区——通常认为这种环境有利于常绿树物种生长。我们在落叶松自然分布范围内的20个地点，比较了落叶松属与共生的常绿针叶树之间的叶片碳同位素判别率（Δ）、瞬时水分利用效率、叶片总氮浓度和比叶面积（部分地点）。除了美国西部山间干旱地区的西部落叶松外，在77%的地点，落叶松的Δ显著（P < 0.05）高于共生的常绿针叶树，这表明落叶松水分利用效率较低。在海拔高于3000米的地方，落叶松属和共生针叶树的Δ趋于一致，这表明水分不是限制资源。叶片氮浓度和比叶面积是与高光合能力呈正相关的两个生态生理特征。在88%的地点，落叶松的叶片氮浓度显著高于常绿针叶树，落叶松的比叶面积约为共生针叶树的三倍。未来的研究应探讨全球变暖可能对落叶松林分布产生的潜在影响，因为落叶松的水分利用效率通常低于共生的常绿针叶树，且寒带和高纬度环境可能经历最大程度的气候变暖。
