CO_(2)stimulation and response mechanisms vary with light supply in boreal conifers  

北方针叶树CO_(2)的刺激和响应机制随光强而变化

作　　者：Qing-Lai Dang Jacob Marfo Fengguo Du Rongzhou Man Sahari Inoue 

机构地区：[1]Faculty of Natural Resources Management,Lakehead University,ON P7B 5E1,Canada [2]Forestry College,Beihua University,Jilin 132013,China [3]Ontario Ministry of Natural Resources and Forestry,Ontario Forest Research Institute,ON P6A 2E5,Canada

出　　处：《Journal of Plant Ecology》2021年第2期291-300,共10页植物生态学报（英文版）

基　　金：by Natural Sciences and Engineering Research Council of Canada Discovery grants to Q.L.Dang(Project No.203198-2013-RGPIN);Lakehead University Graduate Assistantships to J.Marfo.

摘　　要：Aims Black spruce(Picea mariana[Mill.]B.S.P.)and white spruce(Picea glauca[Moench]Voss.)are congeneric species.Both are moderately shade tolerant and widely distributed across North American boreal forests.Methods To understand light effects on their ecophysiological responses to elevated CO_(2),1-year-old seedlings were exposed to 360µmol mol−1 and 720µmol mol−1 CO_(2)at three light conditions(100%,50%and 30%of full light in the greenhouse).Foliar gas exchanges were measured in the mid-and late-growing season.Important Findings Elevated CO_(2)increased net photosynthesis(Pn)and photosynthetic water use efficiency,but it reduced stomatal conductance and transpiration.The stimulation of photosynthesis by elevated CO_(2)was greatest at 50%light and smallest at 100%.Photosynthesis,maximum carboxylation rate(Vcmax)and light-saturated rate of electron transport(Jmax)all decreased with decreasing light.Elevated CO_(2)significantly reduced Vcmax across all light treatments and both species in mid-growing season.However,the effect of elevated CO_(2)became insignificant at 30%light later in the growing season,with the response being greater in black spruce than in white spruce.Elevated CO_(2)also reduced Jmax in white spruce in both measurements while the effect became insignificant at 30%light later in the growing season.However,the effect on black spruce varied with time.Elevated CO_(2)reduced Jmax in black spruce in mid-growing season in all light treatments and the effect became insignificant at 30%light later in the growing season,while it increased Jmax later in the season at 100%and 50%light.These results suggest that both species benefited from elevated CO_(2),and that the responses varied with light supply,such that the response was primarily physiological at 100%and 50%light,while it was primarily morphological at 30%light.黑云杉(Picea mariana[Mill.]B.S.P.)和白云杉(Picea glauca[Moench]Voss.)是同属物种,两者都是适度耐阴,并且在北美北方针叶林中广泛分布。为了了解光照对CO_(2)浓度升高的生理生态反应的影响,在三种光照条件下(温室中光照设置为100%、50%和30%)将一年生的两种幼苗暴露在360和720µmol mol–1浓度的CO_(2)环境中,测定了其中后期叶面气体交换量。研究结果表明,CO_(2)的浓度升高提高了净光合速率(Pn)和光合水分利用效率,但降低了气孔导度和蒸腾作用。CO_(2)对光合作用的刺激在50%光照下最大,在100%光照下最小。光合作用、最大羧化速率(Vcmax)和光饱和电子传递速率(Jmax)均随光照强度的降低而降低。升高的CO_(2)在所有光照处理中显著降低了Vcmax,在生长季节中期,两种云杉的Vcmax均显著降低,但在生长季节后期,当光照达到30%时,这一影响变得不明显,而且黑云杉的响应大于白云杉。CO_(2)浓度升高也降低了白云杉的Jmax,但在生长季后期30%光照时,这种影响变得不显著。但CO_(2)浓度升高对黑云杉的影响随时间而变化。在所有光照处理中,CO_(2)浓度升高降低了黑云杉生长中期的Jmax,且在生长后期30%光照时影响不显著,但在100%和50%光照时,Jmax升高。这些研究结果表明,两个树种植物都受益于CO_(2)浓度的升高,但它们的响应机制随着光照的增加而变化:即在100%和50%光照下,它们的响应主要是生理上的,而在30%光照下,它们的响应主要是形态上的。

关 键 词：black and white spruce boreal forest CO_(2)–light–species interaction 

分 类 号：S76[农业科学—森林保护学]