Elevated growth temperatures reduce the carbon gain of black spruce [ Picea mariana (Mill.) B.S.P.]

作者：Danielle A. Way, Rowan F. Sage · 发表于：Global Change Biology · 年份：2007 · DOI：10.1111/j.1365-2486.2007.01513.x · 被引用次数：194 · 研究领域：Plant Water Relations and Carbon Dynamics、Plant Stress Responses and Tolerance、Plant responses to elevated CO2

Abstract We explored the effect of high‐growth temperatures on a dominant North American boreal tree, black spruce [ Picea mariana (Mill.) B.S.P.]. In 2004 and 2005, we grew black spruce at either 22 °C/16 °C day/night temperatures [low temperature (LT)] or 30°/24 °C [high temperature (HT)] and determined how temperature affected growth, leaf morphology, photosynthesis, respiration and thermotolerance. HT spruce were 20% shorter, 58% lighter, and had a 58% lower root : shoot ratio than LT trees. Mortality was negligible in the LT treatment, but up to 14% of HT seedlings died by the end of the growing season. HT seedlings had a higher photosynthetic temperature optimum, but net photosynthesis at growth temperatures was 19–35% lower in HT than LT trees. HT seedlings had both a lower apparent maximum ribulose‐1,5‐bisphosphate carboxylation capacity ( V cmax ) and a lower apparent maximum electron transport rate ( J max ) than LT trees, indicating reduced allocation to photosynthetic components. Consistently, HT needles had 26% lower leaf nitrogen content than LT needles. At each measurement temperature, HT seedlings had 20–25% lower respiration rates than LT trees; however, this did not compensate for reduced photosynthetic rates at growth temperature, leading to a greater ratio of dark respiration to net carbon dioxide assimilation rate in HT trees. HT needles had 16% lower concentrations of soluble sugars than LT needles, but similar starch content. Growth at high temperatures...