择伐对小兴安岭地区针阔混交林土壤呼吸温度敏感性的影响

利用LI8100土壤二氧化碳排放通量全自动测量系统,测定小兴安岭地区针阔混交林不同强度择伐后4年的林地土壤呼吸速率和土壤温度。运用Q10模型分析择伐后林地土壤呼吸速率对土壤温度的敏感性。结果表明:择伐后林地Q10值高于未采伐林地,较高强度(60%,71%)的择伐使土壤呼吸速率对土壤温度具有高的敏感性。这一现象是3个土壤各组分呼吸对土壤温度响应综合作用的结果。枯枝落叶层呼吸速率对土壤温度的敏感性较差,根呼吸速率和矿质土壤层呼吸速率对土壤温度的敏感性较高。     

集约经营雷竹林土壤呼吸年动态变化规律及其影响因子

在浙江临安市雷竹主产区定位监测1年内土壤各组分呼吸动态。结果表明:雷竹林地土壤总呼吸速率、土壤生物异养呼吸速率及根系自养呼吸速率的年平均值分别为5.42,2.24和2.89μmolCO2·m-2s-1;1年中分别在2和7月出现土壤呼吸峰值;雷竹林地土壤年释放CO2量为73.40t·hm-2a-1,其中林地异养呼吸和自养呼吸分别占总呼吸的45.67%和54.33%;土壤呼吸、土壤生物异养呼吸和土壤根系自养呼吸均与土壤温度呈明显的指数关系,以土壤5cm深处温度为依据得到的温度系数(Q10值)分别为1.70,1.86和1.48,土壤总呼吸与土深5cm处土温、8:00气温、土壤水溶性有机碳含量和土壤总有机碳含量呈显著正相关(P<0.01),而土壤含水量、8:00大气相对湿度和土壤水溶性有机碳含量与土壤呼吸无显著相关性。     

第十届花博会广东“粤芳园”的传统山水造园手法应用

造园,古往今来,神形兼备,“神”通过意境的营造以传达园的精神与韵味,“形”通过地形空间的塑造以形成高低、远近、虚实、藏露的丰富场景,为意境的营造提供平台。神与形相互烘托,互相成就,共同体现了中国传统造园的精髓。第十届花博会广东“粤芳园”通过地形的塑造,营造了“高山流水”“小中见大”的丰富空间与景观层次,以曲径通幽、蜿蜒前行的园径引导游人沉浸式体验绿意盎然、花木繁茂的岭南水乡的风采,在移步换景中感受中国园林的“形”与“神”,体现了传统山水造园手法在当代园林的应用。     

基于UHPLC–QTOF–MS技术的五倍子单宁成分分析

目的 基于超高效液相色谱–四极杆飞行时间–质谱（UHPLC–QTOF–MS）技术分析五倍子中单宁成分,建立一种有效的五倍子单宁成分测定方法,并解析单宁的裂解规律。 方法 使用高温和超声波辅助方法提取五倍子中的酚类化合物,基于二级质谱推定化合物的裂解途径。 结果 共鉴定到20种化合物,包含14种没食子单宁、3种酚酸、2种没食子酸酯和1种黄烷醇。以高温121℃为提取条件,均未鉴定到分子质量高于1 500 Da的没食子单宁,而在超声波辅助提取的五倍子水提取液中,成功地检测到1–O–没食子酰基葡萄糖至14–O–没食子酰基葡萄糖,其中,超声功率1 500 W,提取温度65℃条件下,鉴定到更多的没食子单宁异构体。MS/MS图谱显示,五倍子单宁主要通过没食子酸、没食子酰基、糖苷、水、羧基的损失进行裂解。 结论 本研究证明,超声波辅助提取条件下,应用UHPLC–QTOF–MS技术能够全面高效地分析五倍子中的单宁成分,本研究为富含单宁的植物的化学成分研究提供参考依据。     

10kV、630kvA及以下配电变压器保护配置方式的合理选择

10kV配电变压器的保护配置主要有断路器、负荷开关或负荷开关加熔断器等。对10kV环网供电单元和终端用户10 kV配电变压器采用断路器、负荷开关加熔断器组合的保护配置方式进行技术、经济比较,供配电网的设计和运行管理部门参考。     

长白山典型阔叶红松林土壤二氧化碳排放通量

随着大气CO2浓度的升高,主要由其引起的温室效应与对生物新陈代谢的影响变得越来越显著。森林生态系统在全球碳循环中扮演着重要的角色。为了评估和理解森林土壤CO2通量及其随空气和土壤温度的季节和昼夜变化规律,我们在长白山北坡典型阔叶红松林内利用静态箱技术进行了原位观测。实验在整个生长季(6月初至9月末)昼夜进行,利用气相色谱进行气体分析。结果表明: 长白山阔叶红松林土壤是大气二氧化碳源,其CO2通量具有明显的季节和昼夜变化规律。通量的变化范围是(0.30-2.42)μmol穖-2穝-1,平均值为0.98μmol穖-2穝-1。土壤CO2排放的季节规律表明,土壤CO2通量的变化与气温和土壤温度的变化有关。CO2平均通量的最大值出现在7月((1.27±23%)μmol穖-2穝-1),最小值出现在9月((0.5±28%)μmol穖-2穝-1)。土壤CO2的昼夜波动与土壤温度变化有关,而在时间上滞后于温度的变化。森林下垫面土壤CO2通量与土壤温度显著相关,与6cm深度土层温度相关系数最大。基于气温和土壤温度计算的Q10值范围为2.09-3.40。图2表3参37。     

长沙市大气颗粒物PM2.5和PM10的时空分布特征

利用 2017—2018 年长沙市空气质量监测数据,分析了长沙市大气颗粒物 PM2.5 和 PM10 的时空 分布特征。结果表明：长沙市大气颗粒物 PM2.5 和 PM10 均表现为冬季 > 秋季 > 春季 > 夏季,冬季浓度最 高,PM2.5 和 PM10 分别为 62.87 和 89.22 μg · m-3;空间变化特征：PM2.5 浓度为长沙城区＞长沙县＞宁乡 县＞望城区＞浏阳市, PM10 浓度为长沙城区＞宁乡县＞长沙县＞望城区＞浏阳市;颗粒污染物 PM2.5 与 PM10 浓度有极显著的线性相关性,r = 0.853,P=0.000（P ＜ 0.01）;降水对大气颗粒物有显著消减作用, 使 PM2.5、PM10 的浓度分别下降了 17.93% 和 27.67%。通过调整能源结构、提倡绿色出行、增加绿量、人 工降水等可有效控制长沙市大气颗粒物污染。     

Stem respiration is influenced by pruning and girdling in Pinus sylvestris

Abstract

Stem respiration was measured in the growing season (June to July) and in the dormant season (October) to detect cambial activity induced by pruning live branches or girdling stems in Scots pine trees (Pinus sylvestris L.) growing in northern Sweden. Immediately after the treatments, the treatment:control ratio of stem respiration increased to between 1.38 and 1.44 in the pruning treatment and between 1.17 and 1.20 in the girdling treatment. The treatment:control ratio of stem respiration then decreased by the end of July, to 0.65 in the pruning treatment and 0.55 in the girdling treatment. In October, the treatment:control ratios were higher: between 0.87 and 0.97 in the pruning treatment and between 0.85 and 0.97 in the girdling treatment. In both pruning and girdling treatments, the time trends of stem respiration rates largely followed those of stem temperatures: the stem respiration rate increased exponentially with an increase in stem temperature. The Q ₁₀ values were 2.83–4.05 and 2.57–2.89 in the pruning treatment and control, and 2.10–2.60 and 1.99–3.19 in the girdling treatment and control, respectively. In most cases, the values of Q ₁₀ in both treatments did not differ significantly from those in the controls.     

Iridoid, phenylethanoid and flavonoid glycosides from Sideritis trojana

From the MeOH extract of Sideritis trojana, a new iridoid glycoside, 10-O-(E)-feruloylmelittoside (1) was obtained in addition to four known iridoid glycosides [melittoside (2), 10-O-(E)-p-coumaroylmelittoside (3), stachysosides E (4) and G (5)]. Moreover, five phenylethanoid glycosides [verbascoside (6), isoacteoside (7), lamalboside (8), leonoside A (9), isolavandulifolioside (10), three flavone glycosides (isoscutellarein 7-O-[6'-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (11), 4'-O-methyisoscutellarein 7-O-[6'-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (12), 3'-hydroxy-4'-O-methyisoscutellarein 7-O-[6'-O-acetyl-β-allopyranosyl-(1→2)]-β-glucopyranoside (13) and a benzylalcohol derivative (di-O-methylcrenatin) were obtained and identified. The structures were elucidated on the basis of NMR and HRMS data. All compounds were tested for their antioxidant activity by in vitro TEAC assay and some of them exhibited moderate activity (0.97-1.44 mM) when compared with the reference compound (quercetin 1.86 mM). Glycosides 6-13, the most active compounds in the TEAC assay, were also tested by flow cytometry to evaluate their ability to affect the levels of reactive oxygen species (ROS) in human prostate cancer cells (PC3).     

Stand level estimation of root respiration for two subtropical plantations based on in situ measurement of specific root respiration

In this study, the stand level root respiration was estimated for two monoculture plantations: Acacia crassicarpa and Eucalyptus urophylla, based on in situ measurement of specific root respiration using simplified root chamber method. The respiration rates of fine roots (<5 mm) were significantly higher than those of coarse roots (>5 mm) for both A. crassicarpa and E. urophylla species. The root respiration of A. crassicarpa showed a clear seasonal pattern with a higher value in the wet season. For E. urophylla, the seasonal pattern was observed for fine roots but not for coarse roots. After determining the biomass of fine roots and coarse roots and their specific rates of respiration at different time points, root respiration at the stand level (R_a) was estimated using a direct up-scaling model. We found that the R_a accounted for 14% and 19% of total soil respiration (R_s) for A. crassicarpa and E. urophylla, respectively. The fine (R_Tf) and coarse (R_Tc) root respiration at the stand level accounted for about 47% and 53% of the R_a for A. crassicarpa, and accounted for 58% and 42% for E. urophylla. This suggests that coarse root respiration cannot be ignored when estimating the root respiration at the stand level. Our results showed that the Q₁₀ values were more accurate in representing the temperature dependence when the confounding effect of soil moisture was considered. This study introduces an alternative approach to estimate stand level root respiration, but its reliability is largely dependent on the accuracy of root biomass quantification.