黄河三角洲芦苇湿地生态系统碳、水热通量特征

利用涡度相关法对黄河三角洲芦苇湿地生态系统进行了连续两年的通量观测,对2009—2010年生长季芦苇湿地的净生态系统碳交换量(NEE),感热通量(Hs)和潜热通量(LE)数据进行了分析。结果表明,在日尺度上,芦苇湿地NEE日变化特征表现为两个CO2吸收高峰,分别出现在11:00和16:00左右,其特点是在午间出现了碳交换通量的降低。CO2吸收的日最大值在两个生长季出现的时间有所不同,分别出现在2009年7月(-0.30 mg CO2m-2s-1)和2010年6月(-0.37 mg CO2m-2s-1)。CO2排放的日最大值两个生长季均出现在9月,分别为0.19和0.25 mg CO2m-2s-1。Hs和LE的日动态均为单峰型,极值都出现在中午前后,生长季生态系统的能量消耗主要以潜热为主,且在日尺度上,热通量和NEE有显著的负相关关系。在季节尺度上,芦苇湿地生长季具有明显的碳汇功能,2009年生长季生态系统白天固定354.63 g CO2/m2,同时期夜间释放159.24 g CO2/m2,净CO2吸收量为-195.39 g CO2/m2。2009年整个生长季生态系统总初级生产力(GPP)为-651.13 g CO2/m2,生态系统呼吸(Re)为455.74 g CO2/m2,系统表现为碳汇。路径分析表明:光合有效辐射(PAR)显著影响NEE的日动态(R2=0.46—0.84),而NEE的季节动态主要受土壤温度的影响,降水和PAR的影响次之。     

黄河小浪底人工混交林冠层CO2储存通量变化特征

基于黄河小浪底人工混交林2008年的CO2浓度和碳通量数据,分析了不同天气条件下CO2浓度在时间和空间上的变化特征,对比了CO2浓度廓线法和涡度相关法估算的CO2储存通量,研究了CO2储存通量的日、季变化特征。结果表明:人工混交林冠层上方月平均CO2浓度具有明显的季节变化规律。月平均CO2浓度最大值出现在3月(370μmol/mol),最低值出现在8月(347μmol/mol)。涡度相关法估算的CO2储存通量比廓线法所得结果偏低9%。生长季,冠层CO2储存通量和净生态系统碳交换量(NEE)日平均值分别为-0.0004和-0.091 mg CO2m-2s-1,冠层CO2储存通量在NEE中仅占0.4%。2008年CO2储存通量和NEE分别为-46.1、-1133 g CO2m-2a-1。在年尺度上,CO2储存通量占NEE的4.1%。因此,在日和年尺度上计算黄河小浪底人工混交林NEE时,CO2储存通量可以忽略。     

安吉毛竹林生长季CO_2浓度的时空特征

试验采用7层CO2廓线系统对安吉毛竹林生长季(5—10月)CO2浓度进行连续监测,同时结合同步CO2通量和气象资料,分析安吉毛竹林CO2浓度的时空动态和CO2储存通量的变化特征。结果表明:安吉毛竹林生长季CO2浓度表现出明显的日变化、季节变化和垂直梯度。日尺度上,CO2浓度在日出前后达到最大,随后出现一段快速释放过程,午后达到全天最低值;整个生长季尺度上,7月份林间CO2浓度最低(368.1μmol·mol-1),10月份最高(402.6μmol·mol-1);垂直梯度方面,林冠上层CO2垂直梯度明显小于林冠层和林冠下层;林冠层和林冠上层垂直梯度变化趋势较为一致,白天均为正值,呈现为碳汇,夜间为负值,呈现为碳源,林冠下层CO2梯度全天均为负值。利用廓线系统计算毛竹林CO2储存通量,半小时和日尺度上,CO2储存通量分别占净生态系统CO2交换量(NEE)的25.5%和8.9%,而在月尺度上仅占NEE的0.22%。因此,在半小时及日尺度上计算NEE时不可忽略CO2储存通量,而在计算月尺度及更长时间尺度NEE时可以忽略CO2储存通量。     

珠三角城市绿地CO2通量的季节特征

城市绿地是城市碳循环的重要组成部分,利用长期定位观测资料估算珠三角典型城市绿地的CO2通量,可以为应对气候变化、评价区域碳源汇提供参考。应用2009、2010年,东莞市植物园内的涡度相关法CO2通量定位观测资料,分析了净生态系统交换量(NEE)的年变化及其与气象要素的关系,结果表明:(1)年平均NEE总量为-104.2 gC.m-.2a-1,表明城市绿地生态系统具有固碳能力。(2)NEE随光温条件变化呈现明显的季节动态,12至3月表现为碳源,其他月份表现为碳汇。(3)根据白天NEE与光合有效辐射(PAR)逐月拟合Michaelis-Menten方程,得到年平均表观初始光能利用率(α)为(0.00134±0.00035)mgCO.2μmol-1光子,年平均光饱和生态系统生产力(Pmax)为(1.006±0.283)mgCO.2m-.2s-1。(4)利用夜间呼吸(Reco)与5 cm土壤温度(Ts)拟合指数方程,得到年平均Reco总量为1378.1 gC.m-.2a-1。(5)NEE与PAR、气温(Ta)和饱和水压差(VPD)的相关性分析显示,NEE与PAR偏相关系数的绝对值大于Ta和VPD,表明PAR对NEE的影响最大。     

青藏高原高寒灌丛非生长季节CO2通量特征

利用2003年和2004年涡度相关系统通量观测资料,对青藏高原高寒灌丛非生长季节CO2通量特征及其主要影响因子进行了分析。(1)从净生态系统CO2交换(NEE)日变化特征看,除13:00~19:00时有较小的CO2净释放以外,其余时段NEE均很小;(2)高寒灌丛非生长季月份间NEE差异明显,4月和10月是CO2净释放量较大,1月和12月CO2净释放量较小;(3)相对温带草原(高杆草大草原)草地类型,低温抑制下的青藏高原高寒灌丛生态系统非生长季节日平均CO2释放率较低;(4)高寒灌丛非生长季NEE日变化模式与5 cm土壤温度变化呈显著正相关,土壤温度是影响非生长季节青藏高原高寒灌丛NEE变化的主导气候因子,同时NEE变化还受降水的影响。     

鼎湖山针阔叶混交林CO2浓度及通量变化特征

该研究采用珠三角典型森林植被生态系统的鼎湖山南亚热带常绿阔叶林通量观测站2012年CO2通量资料和气象资料,分析了CO2通量、净生态系统CO2交换量及CO2浓度的变化特征,及其与气象因子的关系。结果表明:(1) CO2浓度日变化呈“一峰一谷”变化形态,在夜间或日出前后出现最大值,在午后到达最小值; CO2通量日变化呈“单谷”曲线,在白天中午前后到达最小值(负值),夜间和早晨较高(正值)。(2) CO2通量季节平均值的高低依次为春季夏季冬季秋季,CO2浓度季节平均值的高低次序则为冬季春季秋季夏季,即非生长季高于生长季节,这可能与植物物候的季节变化所引起的CO2源汇强度改变有关。(3) 2012年鼎湖山森林生态系统的CO2年均浓度为664.7 mg·m-3,CO2通量年均值为-0.079 mg·m-2·s-1,NEE为-611 g C·m-2·a-1,表明鼎湖山针阔叶混交林近年来处于快速生长过程中,具有较强的碳汇功能。(4) CO2通量及浓度与气温、饱和水气压差均成显著负相关关系,其中CO2浓度与气温的相关性最高,其次为饱和水汽压差,表明气温和饱和水汽压差是影响CO2浓度和通量的关键气象因子。受人类活动及气候变化的影响,近年来鼎湖山森林生态系统的碳汇功能有所增强。     

锡林浩特草原净生态系统碳交换量特征及源区分布

为探究草原生态系统固碳能力,利用锡林浩特国家气候观象台2018—2021年的涡动相关资料分析了锡林浩特草原生态系统CO₂通量的变化特征以及环境因子对CO₂通量的影响,并对通量源区分布进行了探讨。结果表明：研究区全年盛行西南风,生长季的源区面积大于非生长季,大气稳定条件下的源区面积大于不稳定条件;90%贡献率的源区最大长度接近400 m,与经典法则估算的长度一致。锡林浩特草原净生态系统碳交换量(NEE)具有明显的日变化和季节变化,生长季白天为碳汇,夜间为碳源,非生长季白天和夜间均为弱碳源。2018—2021年,年总NEE分别为-15.59、-46.28、-41.94和-78.14 g C·m^-2·a^-1,平均值为-45.49 g C·m^-2·a^-1,表明锡林浩特草原有较强的固碳能力。饱和水汽压差和光合有效辐射有助于草原生态系统吸收大气中CO₂;夜间,当温度高于0℃时,气温和土壤温度升高会促进植被呼吸作用释放CO₂。     

浙江天目山老龄森林生态系统CO_2通量特征

物种丰富的异龄老龄森林对陆地生态系统动态模型及全球碳收支具有十分重要的意义.目前,我国关于老龄森林碳通量的研究很少,亚热带地区的老龄林更鲜有报道.本研究利用涡度相关技术观测了我国中亚热带地区的浙江天目山一个老龄常绿落叶阔叶混交林生态系统的CO_2通量.以2013年7月到2014年6月的观测数据为依据,分析了此老龄林净生态系统碳交换量(NEE)、生态系统呼吸量(R_e)、生态系统总交换量(GEE)的变化.结果表明:研究期间老龄林常绿落叶阔叶混交林生态系统NEE月总量除12、2月为正值外(表现为碳源),其余月份均为负值(表现为碳汇).NEE月总量平均为-61.52 g C·m~(-2),各月碳吸收量以6月(-149.40 g C·m~(-2))最高,10月次之,呈双峰变化;最大碳源出现在2月(23.45g C·m~(-2)).各月NEE平均日变化差异明显,6月的平均通量峰值最大,达到-0.98 mg·m~(-2)·s~(-1),12月最小,为-0.35mg·m~(-2)·s~(-1);NEE符号改变的时间也呈明显的季节变化特征;全年NEE、R_e、GEE分别为-738.18、931.05、-1669.23g C·m~(-2).与相近纬度相近林型的其他森林生态系统相比,由于其复层结构和多种幼龄更新树木的存在,其测定的固碳量较大.表明我国中亚热带天目山地区的老龄森林生态系统不是处于碳收支稳定状态,而是具有相对较高的固碳能力.     

黄土塬区麦田CO2通量季节变化

利用涡度相关法对黄土塬区小麦地CO2通量季节变化进行了研究。结果表明：（1）小麦CO2通量日变化与生育期、光合有效辐射、土壤温度密切相关。（2）小麦各生育期CO2的平均日收支由大到小依次为拔节孕穗期〉返青期〉起身期〉抽穗期〉成熟期〉灌浆期〉出苗分蘖期〉越冬期。（3）白昼CO2通量与光合有效辐射在出苗分蘖期、起身期、成熟期几乎不相关,在灌浆期低度相关,在其他生育期内都达到了显著相关。CO2通量与夜间2cm土壤温度在越冬、起身、拔节孕穗期显著相关,其他5个生育期内为低度相关。（4）小麦收割后表现为碳源,各天具体状况与前一天是否降雨、当天的天气状况有关。     

浙江天目山老龄森林生态系统CO2通量特征

物种丰富的异龄老龄森林对陆地生态系统动态模型及全球碳收支具有十分重要的意义.目前,我国关于老龄森林碳通量的研究很少,亚热带地区的老龄林更鲜有报道.本研究利用涡度相关技术观测了我国中亚热带地区的浙江天目山一个老龄常绿落叶阔叶混交林生态系统的CO₂通量.以2013年7月到2014年6月的观测数据为依据,分析了此老龄林净生态系统碳交换量(NEE)、生态系统呼吸量(R_e)、生态系统总交换量(GEE)的变化.结果表明: 研究期间,老龄林常绿落叶阔叶混交林生态系统NEE月总量除12、2月为正值外(表现为碳源),其余月份均为负值(表现为碳汇).NEE月总量平均为-61.52 g C·m^-2,各月碳吸收量以6月(-149.40 g C·m^-2)最高,10月次之,呈双峰变化;最大碳源出现在2月(23.45 g C·m^-2).各月NEE平均日变化差异明显,6月的平均通量峰值最大,达到-0.98 mg·m^-2·s^-1,12月最小,为-0.35 mg·m^-2·s^-1;NEE符号改变的时间也呈明显的季节变化特征;全年NEE、R_e、GEE分别为-738.18、931.05、-1669.23 g C·m^-2.与相近纬度相近林型的其他森林生态系统相比,由于其复层结构和多种幼龄更新树木的存在,其测定的固碳量较大.表明我国中亚热带天目山地区的老龄森林生态系统不是处于碳收支稳定状态,而是具有相对较高的固碳能力.     

Quantitative flavonoid variation in Lupinus sericeus

One hundred and eighty-one plants representing 32 individual populations of Lupinus sericeus were collected from throughout the range of the species. Quantitative analyses of flavonoid derivatives were performed using high performance liquid chromatography. Peak height data were subjected to multivariate analysis. Principal components analysis suggested the existence of a north-south cline based upon differences in orientin concentration. Canonical variates analysis suggested that southerly, central and northerly populations were distinguishable. Simple statistical tests on orientin concentration, the major flavonoid seen in the study, clearly distinguished southerly populations from all others. Seeds were collected from representative populations from the range of L. sericeus and the plants obtained therefrom were grown under uniform conditions. Analysis of orientin concentration in these plants showed no significant differences between populations. We conclude from these studies that all L. sericeus plants appear to have similar capacities to accumulate orientin, and that differences in concentration of this compound seen in naturally occurring plants are a reflection of environmental influences and cannot be used as support for any infrageneric taxonomic distinctions.     

Cyanogenesis in Cotoneaster-arten

The presence of the cyanogenic glycoside prunasin in leaves and fruits of Cotoneaster species was confirmed by GLC. In addition amygdalin was found in ripe fruits. The variation in prunasin and amygdalin was measured during development of the flowers and fruits of C. praecox and C. bullata. The importance of these findings for chemotaxonomy and physiology is discussed.     

柯-青冈常绿阔叶林优势树种叶片性状变异及适应策略

厘清叶片功能性状的变异及性状间的权衡关系，对揭示植物对环境变化的响应及适应策略具有重要意义。以中亚热带柯(Lithocarpus glaber)-青冈(Cyclobalanopsis glauca)常绿阔叶林为对象，测量了1 hm²固定监测样地内6个优势树种的叶面积(LA)、比叶面积(SLA)、干物质含量(LDMC)、叶片厚度(LT)、叶片碳(LC)、叶片氮(LN)、叶片磷(LP)含量和叶片碳氮比(LC ∶ LN)8个功能性状，采用多重比较、主成分分析(PCA)法分析了群落叶片功能性状的生活型、种内和种间变异及性状间关系。结果表明：(1)群落内叶片功能性状种内、种间差异显著，变异中等(CV： 0.02-0.59)，其结构性状的可塑性较化学性状保守，变异格局符合"性状空间变异分割假说"；针叶树种的LA、SLA显著低于阔叶树种，常绿树种的LC和LDMC最小，而落叶树种的SLA、LN和LP最大以及LT和LC ∶ LN最小。(2)群落叶片功能性状变异主要来源于生活型和种间变异，种内变异亦有显著贡献；生活型对多数性状的贡献率较大，其对LDMC、LC ∶ LN的贡献分别高达93.11%和91.76%；种间变异(LDMC除外)对结构性状的贡献率均高于化学性状；种内变异对LP的贡献率(23.66%)较种间变异高。(3)叶片性状之间多表现出显著相关关系，针叶树和阔叶树在PCA排序图中聚集于不同区域，叶经济型谱在柯-青冈群落中具有适用性。不同树种通过叶片结构、化学性状之间的权衡策略来适应环境变化，从而实现群落物种共存。结果可为理解森林群落物种的环境适应策略、预测群落动态变化和制定植被恢复措施提供科学依据。     

Geographic patterns of monoterpenoid composition in Satureja douglasii

Monoterpenoid composition of mature leaves from populations distributed throughout the range of Satureja douglasii was determined by GLC. Five compositional types (I–V) were characterised, based on the high relative proportions of either carvone, pulegone, isomenthone, menthone or bicyclic compounds (camphenecamphor). These compositional types occured in restricted but overlapping portions of the species range. All samples contained camphene and camphor, amounts of which varied clinally along latitudinal gradient. Transplants were grown under greenhouse conditions. Although some populations exhibited significant environmental modification in amounts of principal constituents, the patterns of geographic variation were retained. Compositional types I–IV are based on compounds having -menthane structures and relationships among them are consistent with single gene actions within a common biosynthetic pathway. Using the dominant components of the collection site vegetation as an indication of habitat conditions, correlation of the genetically-determined compositional variation with environmental conditions was attempted. The distribution of the compositional types was partially isolated in this manner. Environmental factors which might be controlling the genetically-determined variation are discussed.     

Evolutionary responses of stomatal density to global CO2 change

Stomatal density is known to respond to CO₂ levels during leaf development. Current interest in the increasing concentration of atmospheric CO₂ has stimulated much experimentation on the responses of plants to relatively short-term exposure in artificially high CO₂ levels. Attempts to extrapolate from short-term to long-term responses raise fundamental questions concerning evolutionary change in response to rising global CO₂ levels. We consider the improved water use efficiency observed under elevated CO₂ levels to be the main driving force of natural selection affecting the genotypic component controlling stomatal density. Whether a response is merely phenotypic or becomes incorporated into the genotype depends on two factors: (i) the time scale of exposure and (ii) the generation time of a species. Measurements of stomatal density on fossil leaves of Salix herbacea through a glacial cycle covering the last 140000 years have shown a decrease in stomatal density in response to the rising CO₂ levels of this period. This accords with the shorter-term observations on leaves of trees seen in herbarium specimens where the stomatal density has decreased in response to the rising CO₂ levels of the last 200 years. The results indicate that natural selection over the 140000-year period may have favoured a similar response to that shown by trees phenotypically over the last 200 years. Since there is now some evidence for the genetic control of stomatal density, the role of natural selection affecting it must be considered when translating responses from short-term experiments to predict how stomatal density will be affected by long-term climatic and atmospheric change.     

荧光原位杂交技术在植物多倍体起源与进化研究中的应用

多倍化是植物物种形成与多样化的重要原动力。研究植物特别是一些重要经济作物和园艺植物多倍体的起源与进化,不仅对于揭示多倍体形成过程中性状变异的分子机制具有重要意义,而且可为植物遗传资源的保护与利用提供理论和技术支持。作为连接基因组序列片段到染色体组的桥梁,荧光原位杂交技术长期被广泛用来研究多倍体形成与进化过程中相关特异基因或序列的表达定位、外源染色体检测和鉴定、基因组结构变异等科学问题。因此,在简单介绍荧光原位杂交技术发展历史和植物多倍体主要类型的基础上,主要总结了荧光原位杂交技术在植物多倍体起源与进化相关研究上的应用。     

Volatile oils of mature and juvenile leaves of Juniperus horizontalis: Chemosystematic significance

Comparison of 39 terpenoids between young (juvenile) foliage and mature (adult) foliage from naturally growing plants of Juniperus horizontalis revealed no significant differences. Canonical variate analysis of the terpenoids of J. scopulorum and J. virginiana along with the mature foliage of J. horizontalis and co-plotting juvenile foliage showed a slight loosening of the J. horizontalis group but not enough to blur taxonomic distinctions. These results stand in sharp contrast with the previous work on J. scopulorum and appear to be due to the indeterminant growth pattern seen in J. horizontalis.     

Pathogenesis gene families in the common minimal genome of Staphylococcus aureus are hypervariable

Staphylococcus aureus is a versatile pathogen that shows high levels of inter-strain genetic variability and positive evolution in certain pathogenesis-related genes. Apart from gene content differences, variability in shared genes may affect pathogenicity. Studying such variability requires that the common minimal genome (CMG) be identified. In this study, we have surveyed the CMG of S. aureus with respect to variability amongst orthologous family members, and determined that genes involved in pathogenesis preferentially accumulate variations. A negative correlation between variability of genes and their evolution was found, suggesting a preservation of host-specific function while exhibiting sequence diversity. Variation in key pathogenesis genes in S. aureus might predispose them to functional modulation, thereby playing an important role in evasion of host immunity.     

Infraspecific variation of foliage diterpenes of Dacrydium cupressinum

The unique diterpene lauren-1-ene has only been found in the foliage of Dacrydium cupressinum, the New Zealand rimu, but the levels of this and other diterpenes vary greatly from tree to tree. Diterpene levels are apparently under genetic control, as they are not affected by environmental factors. Male and female trees do not differ significantly, but juvenile trees have lower phyllocladene levels than do adult trees. Different regions of New Zealand contain different proportions of high-laurenene trees.     

Intra- and intraspecific variation of Juniperus virginiana and J. scopulorum seedling based on volatile oil composition

Comparisons of volatile oil constituents were made among samples of juvenile foliage collected from 78 Juniperus virginiana and 28 J. scopulorum seedling sources growing in a “common garden” environment. A canonical variate analysis, a principal coordinates analysis and hybrid distance diagrams of 30 chemical characters indicate both taxa are good species and that they exhibit clinical patterns in the Great Plains. In addition, a possible evoluitonary link between present-day J. virginiana populations in southern Texas and ancient J. scopulorum populations is indicated.