Seasonality and drivers of stem CO2 efflux for four temperate coniferous tree species

Aims Stem CO₂ efflux (E_s) is an important component of annual carbon budget in forest ecosystems, but how biotic and environmental factors regulate seasonal and inter-specific variations in E_s is poorly understood. The objectives of this study were: (1) to compare seasonal dynamics in E_s for four temperate coniferous tree species in northeastern China, including Korean pine (Pinus koraiensis), Korean spruce (Picea koraiensis), Mongolian pine (Pinus sylvestris var. mongolica), and Dahurian larch (Larix gmelinii); and (2) to explore factors driving the inter-specific variability in E_s during the growing and non-growing seasons.
Methods Ten to twelve trees for each tree species were sampled for E_s and stem temperature at 1 cm depth beneath the bark (T_s) measurements in situ with an infrared gas analyzer (LI-6400 IRGA) and a digital thermometer, respectively, from July to October 2013 and March to July 2014. The daily stem circumference increment (S_i), sapwood nitrogen concentration ([N]), and related environmental factors were monitored simultaneously.
Important findings The temporal variation in E_s for the four tree species overall followed the changes in T_s throughout the study period, with the maxima occurring in the summer months (late May to early July) characterized by higher temperature and more rapid stem growth and the minima in spring (late March to April) or autumn (October) having lower temperature. T_s accounted for 42%-91% and 56%-89% of variations in E_s during the growing (May to September) and non-growing (other months) seasons, respectively. Furthermore, apart from T_s, we also found significant regression relationships between E_s and S_i, relative air humidity and [N] during the growing season, but their forms and correlation coefficients were species-dependent. These results indicated that T_s was the dominant environmental factor affecting seasonal variations in E_s, but the magnitude of the effect varied with tree species and growth rhythm. Mean E_s for each of the four tree species was significantly higher in the growing season than in the non-growing season, whereas within the season there were also significant differences in mean E_s among the tree species (all p < 0.05). The temperature sensitivity of E_s (Q₁₀ value) did not differ significantly among the tree species during the growing season, ranging from 1.64 for Dahurian larch to 2.09 for Mongolian pine, but did differ during the non-growing season which varied from 1.80 for Korean pine to 3.14 for Dahurian larch. Moreover, Korean spruce, Mongolian pine and Dahurian larch had significantly greater Q₁₀ values in the non-growing season than in the growing season (p < 0.05). These findings suggested that the differences of the response of E_s to temperature change for different tree species were mainly from the non-growing season. Because the seasonality and inter-specific variability in E_s for these temperate coniferous tree species were primarily controlled by multiple factors such as temperature, we conclude that using a single annual temperature response curve to estimate the annual E_s may lead to more uncertainty.     

开放式空气CO2浓度增高对水稻N素吸收利用的影响

在大田栽培条件下 ,研究空气中CO2 浓度增高 (FACE) 2 0 0 μmol·mol-1对水稻N素吸收及其利用效率的影响 .结果表明 ,FACE处理使水稻不同生育时期的植株含N率显著下降 ;由于干物质生产量显著增大 ,FACE处理使水稻不同生育时期的N素累积量有所提高 ,但无显著影响 ;FACE处理能够显著提高移栽后 2 8d、抽穗期以及成熟期单位N素的干物质生产效率、单位N素的籽粒生产效率和显著提高水稻的N素收获指数 .高N处理的植株含N率、N素累积量均有所增加 ,但使N素生产效率呈现下降趋势 .     

水稻生长及其体内C、N、P组成对开放式空气CO2浓度增高和N、P施肥的响应

采用FACE(Free Air Carbon-dioxide Enrichment)技术,研究了不同N、P施肥水平下,水稻分蘖期、拔节期、抽穗期和成熟期根、茎、叶、穗生长,C/N比,N、P含量及N、P吸收对大气CO₂浓度升高的响应.结果表明,高CO₂促进水稻茎、穗和根的生长.增加分蘖期叶干重,对拔节期、抽穗期和成熟期叶干重没有显著增加.降低茎、叶N含量;增加抽穗期穗N含量,降低成熟期穗N含量;对分蘖期根N含量影响不显著,而降低拔节期、抽穗期和成熟期根N含量.增加拔节期、抽穗期和成熟期叶P含量,对茎、穗、根P含量影响不显著.水稻各组织C含量变化不显著.C/N比增加.显著增加水稻地上部分P吸收;增加N吸收,但没有统计显著性.N、P施用对水稻各组织生物量没有显著影响.高N(HN)比低N(LN)增加组织中N含量,而不同P肥水平间未表现出明显差异.高N条件下高CO₂增加水稻成熟期地下部分/地上部分比.文中还讨论了高CO₂对N、P含量及地下部分/地上部分比的影响机制.     

稻麦轮作FACE系统平台Ⅱ.系统控制和数据分析软件

稻麦轮作水稻田建立开放式空气CO2增加即FACE系统（Free Air C02 Enrichment)的管理、系统所测定及系统控制过程中每天都产生大量数据,用汇编语言和Visual BASIC语言编写的FACE数据采集控制和分析处理软件包能够自动操作任务并利用OLE技术开发Office应用程序的功能,具有系统平台控制、数据采集、原始数据存储备份、日数据处理、月数据处理和任意时间段的FACE系统控制状态分析等功能,FACE系统控制人员可以及时了解FACE系统的控制状态和改善控制精度,研究人员借助软件包可以随时便利地获取所需数据。     

不同水生植物对景观水体CO2与CH4排放通量的影响

城市景观水体是大气CO₂与CH₄的排放热源,而水生植物作为景观水体的重要组成要素,对水体温室气体排放动态的影响并不清楚。选择重庆市观音塘国家湿地公园为研究区,利用漂浮箱法与顶空平衡法对观音塘水域7种不同水生植物分布区进行水-气界面CO₂与CH₄排放通量及CO₂、CH₄溶存浓度进行季节性监测,估算了植物传输对气体通量的贡献。结果表明：1)观音塘水体CO₂与CH₄浓度范围分别为8.0—341.8μmol/L和0.23—5.26μmol/L,排放通量分别为26.5—869.1 mmol m^-2 d^-1和0.40—11.15 mmol m^-2 d^-1,是大气净CO₂与CH₄排放源;2)观音塘开敞水区CO₂与CH₄排放通量低于大部分城市湖泊或景观水体...     

利用GC-MS技术分析油橄榄叶挥发油化学成分

本文采用同时蒸馏萃取法(SDE)提取油橄榄叶挥发油化学成分,利用气相色谱-质谱(GC-MS)联用方法分析并用峰面积归一化法得出各化学成分在挥发油中的百分含量。结果从油橄榄叶挥发油中分离出62各色谱峰,鉴定出56个化合物,占挥发性组分总量的95.6%。其中主要成分为α-芹子烯(13.13%)、β-芹子烯(10.15%)、β-石竹烯(14.29%)、橙花叔醇(6.72%)、α-石竹烯(6.60%)、3-己烯-1-醇(5.03%)、苯乙醛(5.61%)等。     

EMA/CO化疗方案治疗恶性滋养细胞肿瘤的临床疗效观察

目的:恶性滋养细胞肿瘤(Malignant trophoblastic tumor)是胚胎滋养细胞发生病变而产生的恶性肿瘤,严重威胁女性患者的身体健康及生活质量。本研究对EMA/CO(etoposide,methotrexate,actinomycin D,cyclophosphamide and vincristine)化疗方案治疗恶性滋养细胞肿瘤的临床效果及毒副反应情况进行探讨,旨在为该病的临床治疗积累经验。方法:选取我院2010年8月-2012年12月收治的恶性滋养细胞肿瘤患者58例,随机分为研究组和对照组,每组各29例。对照组采用5-Fu+KSM方案进行治疗,研究组采用EMA/CO方案治疗。观察并比较两组患者的治疗总有效率及毒副反应的发生情况。结果:对照组治疗总有效率为75.9%,研究组治疗总有效率为79.3%,两组患者的临床疗效无显著差异(P0.05)。研究组白细胞减少、呕吐及口腔溃疡程度均比对照组轻,差异具有统计学意义(P0.05)。结论:应用EMA/CO化疗方案治疗恶性滋养细胞肿瘤具有积极的作用,不但可以获得较好的近期疗效,且毒副反应较轻,值得临床应用推广。     

国外动态

借助阳光将CO2和H2O变成生物燃料,美国杰能科尝试采用生物异戊二烯生产燃料,用生物技术改进树木性质.     

耦合二氧化碳减排的微藻产业化培养技术

[目的]建立耦合CO2减排的微藻培养技术,在减排CO2的同时,有效降低微藻产业化生产的成本.[方法]以两种微藻所具有的pH快速漂移与高碱适应特性为原理,通过CO2防逸罩简易装备的设计和构建,建立二氧化碳减排技术.[结果]将该技术应用于微藻培养,在嗜碱绿球藻MC-1的CO2减排小试培养中,CO2防逸罩的安装使得通入培养物后全部逸出的CO2被碱性藻液完全吸收,在海水钝顶螺旋藻新藻株(HS331)的工厂化中试培养中,其平均产率达9.54g/( m2· d1),碳源成本降低了57％,并有效避免了碳酸根离子导致的海水钙镁离子沉淀的产生 ;将该技术进一步应用到螺旋藻产业化培养,在保证获得高质量产品的同时,其年产量提高了20％,每年NaHCO3用量减少了66％,碳源成本减少了58％,年减排CO2量约45吨.[结论]本研究实现了CO2减排技术在螺旋藻产业化培养中的应用,有效降低了螺旋藻生产成本,为建立产业化的C02减排新技术奠定了重要的理论与技术基础.