氮沉降对森林生态系统产生了重要影响,但树木个体对氮沉降的生理生态响应过程和机制有待进一步明确。为探究杨树幼苗功能叶经济性状、植株生长以及生物量和碳氮分配对氮添加的响应,本文以欧美杂交杨中金杨2号(Populus×euramericana...氮沉降对森林生态系统产生了重要影响,但树木个体对氮沉降的生理生态响应过程和机制有待进一步明确。为探究杨树幼苗功能叶经济性状、植株生长以及生物量和碳氮分配对氮添加的响应,本文以欧美杂交杨中金杨2号(Populus×euramericana‘Zhongjin2’)幼苗为材料,研究了连续2年氮添加梯度处理(0、3、6和9 g NH_(4)NO_(3)·a^(-1)·plant^(-1))对其叶片光合速率、叶经济性状、生长以及器官间碳氮分配的影响。结果表明:氮添加第一年,随氮添加浓度增加,中金杨叶片变大变薄,叶肉组织厚度显著降低,单位叶面积的净光合速率和气孔导度则随氮添加浓度增加而先升后降,而蒸腾速率、瞬时水分利用效率和光合氮利用效率不变;单株生物量和碳氮元素积累量显著增加,茎器官的碳投资显著增加而根的碳投资显著降低;氮添加第二年,功能叶光合固碳速率随氮添加量增加更快达到饱和,且高剂量氮添加处理表现出氮毒害现象;仅低量氮添加处理的单株生物量积累显著增加,并且进一步增加了对茎器官的碳投资,而中高剂量氮添加的根系生长明显受到抑制。氮添加下中金杨叶片耗水增加导致的茎输水需求增加可能是驱动向茎碳投资的原因之一,而持续降低的根冠比可能会降低其对干旱等逆境的抵抗力。展开更多
The adsorption isotherms of four activated carbons （Norit Rill, Chemviron BPL, Monolit, and Ambersorb-572） have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculat...The adsorption isotherms of four activated carbons （Norit Rill, Chemviron BPL, Monolit, and Ambersorb-572） have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculation has been proposed based on the adsorption isotherms. This distribution provides information about possible changes in the Gibbs free energy caused by the energetic and geometrical heterogeneities of an activated carbon as well as by the adsorbate-related entropic effects. The general character of the adsorption potential distribution is clearly visible by its simple relation to the micropore and mesopore distribution,展开更多
Wildfire is crucial in the regulation of nutrient allocation during the succession of boreal forests.However,the allocation strategies of carbon(C),nitrogen(N)and phosphorus(P)between leaves and fine roots in response...Wildfire is crucial in the regulation of nutrient allocation during the succession of boreal forests.However,the allocation strategies of carbon(C),nitrogen(N)and phosphorus(P)between leaves and fine roots in response to wildfire severities remain poorly studied.We aimed to explore the allocation strategies of C,N and P between leaves and fine roots among different fire severities.We selected four wildfire severities(unburned,low,moderate and high severity)after 10 years recovery in the Great Xing’an Mountains,northeast China,and compared C,N and P concentrations in leaves and fine roots of all species among fire severities using stoichiometry theory and allometric growth equations.Compared with unburned treatment,C concentrations in leaves and fine roots increased at low severity,and leaf N concentration was the greatest at high severity,but the lowest fine root N concentration occurred at high severity.Plant nutrient utilization tended to be P-limited at high fire severity according to the mean value of N:P ratio>16.More importantly,C,N and P allocation strategies between fine roots and leaves changed from allometry to isometry with increasing fire severities,which showed more elements allocated to leaves than to fine roots with increasing fire severities.These changes in patterns suggest that the allocation strategies of elements between leaves and fine roots are of imbalance with the wildfire severity.This study deepens our understanding of nutrient dynamics between plant and soil in ecosystem succession.展开更多
文摘氮沉降对森林生态系统产生了重要影响,但树木个体对氮沉降的生理生态响应过程和机制有待进一步明确。为探究杨树幼苗功能叶经济性状、植株生长以及生物量和碳氮分配对氮添加的响应,本文以欧美杂交杨中金杨2号(Populus×euramericana‘Zhongjin2’)幼苗为材料,研究了连续2年氮添加梯度处理(0、3、6和9 g NH_(4)NO_(3)·a^(-1)·plant^(-1))对其叶片光合速率、叶经济性状、生长以及器官间碳氮分配的影响。结果表明:氮添加第一年,随氮添加浓度增加,中金杨叶片变大变薄,叶肉组织厚度显著降低,单位叶面积的净光合速率和气孔导度则随氮添加浓度增加而先升后降,而蒸腾速率、瞬时水分利用效率和光合氮利用效率不变;单株生物量和碳氮元素积累量显著增加,茎器官的碳投资显著增加而根的碳投资显著降低;氮添加第二年,功能叶光合固碳速率随氮添加量增加更快达到饱和,且高剂量氮添加处理表现出氮毒害现象;仅低量氮添加处理的单株生物量积累显著增加,并且进一步增加了对茎器官的碳投资,而中高剂量氮添加的根系生长明显受到抑制。氮添加下中金杨叶片耗水增加导致的茎输水需求增加可能是驱动向茎碳投资的原因之一,而持续降低的根冠比可能会降低其对干旱等逆境的抵抗力。
基金Natural Science Foundation of Guangdong Province (No. 36566)
文摘The adsorption isotherms of four activated carbons （Norit Rill, Chemviron BPL, Monolit, and Ambersorb-572） have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculation has been proposed based on the adsorption isotherms. This distribution provides information about possible changes in the Gibbs free energy caused by the energetic and geometrical heterogeneities of an activated carbon as well as by the adsorbate-related entropic effects. The general character of the adsorption potential distribution is clearly visible by its simple relation to the micropore and mesopore distribution,
基金funded by the National Key Research and Development Program of China(2017YFC0504004-1).
文摘Wildfire is crucial in the regulation of nutrient allocation during the succession of boreal forests.However,the allocation strategies of carbon(C),nitrogen(N)and phosphorus(P)between leaves and fine roots in response to wildfire severities remain poorly studied.We aimed to explore the allocation strategies of C,N and P between leaves and fine roots among different fire severities.We selected four wildfire severities(unburned,low,moderate and high severity)after 10 years recovery in the Great Xing’an Mountains,northeast China,and compared C,N and P concentrations in leaves and fine roots of all species among fire severities using stoichiometry theory and allometric growth equations.Compared with unburned treatment,C concentrations in leaves and fine roots increased at low severity,and leaf N concentration was the greatest at high severity,but the lowest fine root N concentration occurred at high severity.Plant nutrient utilization tended to be P-limited at high fire severity according to the mean value of N:P ratio>16.More importantly,C,N and P allocation strategies between fine roots and leaves changed from allometry to isometry with increasing fire severities,which showed more elements allocated to leaves than to fine roots with increasing fire severities.These changes in patterns suggest that the allocation strategies of elements between leaves and fine roots are of imbalance with the wildfire severity.This study deepens our understanding of nutrient dynamics between plant and soil in ecosystem succession.
