以浙江天童国家森林公园人工模拟受损常绿阔叶林样地为研究地点,分析了不同干扰下(择伐大树、清理下木、皆伐、皆伐及去除表土层)植被恢复初期5种主要优势树种最大净光合速率(Amax,net photosynthesis based on area)、比叶面积(SLA,spe...以浙江天童国家森林公园人工模拟受损常绿阔叶林样地为研究地点,分析了不同干扰下(择伐大树、清理下木、皆伐、皆伐及去除表土层)植被恢复初期5种主要优势树种最大净光合速率(Amax,net photosynthesis based on area)、比叶面积(SLA,specific leaf area)和叶片氮、磷含量(N,P,leaf nitrogen and phosphor concentration)等叶性状,以期揭示不同树种对干扰的生态适应性.结果表明:(1)干扰后光照强度的增加导致叶片SLA降低,Amax和叶N含量增加;(2)表土层的去除使得土壤磷有效性的减少,从而导致叶P含量的下降,但对Amax的影响较小;(3)高Amax,SLA以及叶N,P含量的落叶树种山鸡椒(Litsea cubeba)具有很强的资源获取能力和高的生产力,从而在植被恢复早期占据竞争优势.木荷(Schima superba)叶N,P含量最低,但在不同干扰下Amax都高于其他常绿树种,且与叶N含量之间存在具有显著正相关性.干扰样地中石栎(Lithocarpus glaber)叶N含量较对照显著增加,并维持在较高水平,与Amax存在显著正相关性,且其叶片抵御强光伤害的能力较强.米槠(Castanopsis carlesii)的Amax,SLA,叶N,P含量均为中等水平,其Amax和SLA对环境具有较强的可塑性,但叶N含量在各样地中较为稳定.栲树(Castanopsis fargesii)的叶性状可塑性较差,Amax小,且利用高光强的能力弱.展开更多
Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sus- tainable production. In order to investigate the effect of various nitrogen to phosphorus ratios o...Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sus- tainable production. In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth, chlorophyll content and accumulation of lipids in Dunaliella tertiolecta, experiments were carried out in modified microalgal medium with inorganic nitrogen （nitrate-nitrogen） or organic nitrogen （urea-nitrogen） as the sole nitrogen source at initial N：P ratios ranging from 1：1 to 32：1. The favorable N：P of 16：1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate. Decrease in chlorophyll content were observed at the N：P of 4：1 in both nitrate-N and urea-N cultures. It was also observed that the maximum lipids concentration was obtained at the N：P of 4：1 in both nitrate and urea nutrient medium. The lipid productivity and lipid content of cultures in the urea-N medium at the N：P of 4： lwere markedly higher than those from cultures with other N：P ratios （p〈 0.05）. The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D. tertiolecta. Conversely, higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitro- gen to phosphorus. The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumu- lation in D. tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.展开更多
基金partially supported by Tianjin Marine Revitalization Plan of Science and Technology (No.KJXH2013-16) from Tianjin Oceanic Administration,China
文摘Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sus- tainable production. In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth, chlorophyll content and accumulation of lipids in Dunaliella tertiolecta, experiments were carried out in modified microalgal medium with inorganic nitrogen （nitrate-nitrogen） or organic nitrogen （urea-nitrogen） as the sole nitrogen source at initial N：P ratios ranging from 1：1 to 32：1. The favorable N：P of 16：1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate. Decrease in chlorophyll content were observed at the N：P of 4：1 in both nitrate-N and urea-N cultures. It was also observed that the maximum lipids concentration was obtained at the N：P of 4：1 in both nitrate and urea nutrient medium. The lipid productivity and lipid content of cultures in the urea-N medium at the N：P of 4： lwere markedly higher than those from cultures with other N：P ratios （p〈 0.05）. The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D. tertiolecta. Conversely, higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitro- gen to phosphorus. The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumu- lation in D. tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.
