秦岭山地松栎混交林主要木本植物组成及更新特征

采用样方法对秦岭南坡中段松栎混交林主要木本植物组成及天然更新特征进行了研究.结果表明:(1)松栎混交林乔木层物种共计40种,油松、锐齿槲栎和华山松为优势种,重要值分别为35.19％、31.99％和8.12％,漆树、栓皮栎和楝木为亚优势种.(2)更新层木本植物共计87种,其中乔木幼苗34种,占总数的39.08％,灌木物种也有一定优势地位,优势种有锐齿槲栎、悬钩子和菝葜等,高度级较小的更新苗在群落内占有较大比例.(3)优势乔木更新特征不同,锐齿槲栎幼苗和幼树密度显著高于油松和华山松,且锐齿槲栎幼苗密度显著高于其幼树,但油松幼苗与幼树、华山松幼苗与幼树间无明显差异.(4)混交林内锐齿槲栎径级结构呈近似倒“J”形分布,种群稳定;油松和华山松种群均呈近似正态分布,大径级个体群相对稳定,但林下幼树不足.该研究结果提示,松栎混交林下油松和华山松更新不良,这将不利于其长期存留于群落中,虽然锐齿槲栎从幼苗到幼树的发育过程中存在更新障碍,但并未影响其种群整体更新,若无大规模干扰,锐齿槲栎将维持逆“J”型的更新方式并成为松栎混交林群落中的第一优势种.     

秦岭山地典型次生林木本植物幼苗更新特征

采用样方法调查了秦岭山地5种典型次生林--油松林、锐齿栎林、红桦林、云杉林和华山松林幼苗的更新特征.结果表明: 不同次生林木本植物幼苗物种分化明显,除锐齿栎林和华山松林外,其余次生林幼苗物种相似性系数均较低;油松林和锐齿栎林木本植物幼苗数量、物种丰富度指数、Simpson优势度指数及均匀度指数均较高,红桦林均最低;云杉林和华山松林幼苗数量及物种多样性指数基本一致.不同次生林幼苗和幼树所占比例存在明显差异,除红桦林幼树数量的比例较大外,其余林分幼苗的比例较大,为云杉林＞油松林＞锐齿栎林＞华山松林.不同林分幼苗萌生比例差异明显,为华山松林＞云杉林＞红桦林＞锐齿栎林＞油松林.锐齿栎林和油松林乔木幼苗比例最高,分别占木本幼苗总种数的68%和51.4%,群落处于演替中期,持续更新能力较强;云杉林、华山松林乔木幼苗比例分别为40%和15%,处于演替后期,更新能力较差;而红桦林中幼苗很难发育成幼树,持续更新能力欠缺.     

秦岭大熊猫栖息地主要森林群落类型稳定性分析

为了揭示秦岭大熊猫栖息地主要森林植物群落稳定性现状,于佛坪和长青国家自然保护区各设置1条样线,每条样线上按海拔每升高100m设置1~4个500m~2(20m×25m)典型样地(共计60个)进行样方调查。在分析调查数据基础上,选取分布最广且具有代表性的16个群落类型林地,并利用模糊数学隶属函数对其优势种更新、林地质量、群落物种多样性、群落复杂性、土壤肥力、保护程度6个方面对各群落类型林地的植物群落稳定性进行综合分析评价。结果表明:(1)栓皮栎群落林下的幼苗和幼树数量相对最多,隶属函数最大,其更新能力较强;华山松群落林下的幼苗和幼树数量为零,其更新能力最差。(2)华山松和油松混交林群落林地的立木蓄积量、平均高度、枯落物厚度等3个隶属函数平均值最高,其林地质量相对最好;油松和锐齿槲栎混交林则相反,林地质量相对较差。(3)群落林地土壤肥力6项指标分析显示,太白红杉林隶属函数值最大,土壤肥力相对较高,而板栗林、亮叶桦林隶属函数较小,土壤肥力相对最低。(4)群落林地物种多样性分析显示,铁杉林隶属函数最大,物种多样性表现更为突出,太白红杉林隶属函数值最小,其物种多样性表现相对最差。(5)铁杉林林地群落的复杂性3个方面隶属函数相对最高,复杂性最高,太白红杉则相对最低。(6)太白红杉、巴山冷杉因分布在保护区核心区域,群落林地的保护程度最高,而毛栗林、亮叶桦因分布于保护区边缘的实验区,保护程度最差。(7)综合对比6个指标隶属函数发现,16个群落林地的稳定性由大到小顺序为:铁杉林短柄枹栎林太白杨林华山松林锐齿槲栎林巴山冷杉林白桦林=红桦林油松+华山松=牛皮桦林油松+锐齿槲栎混交林油松林太白红杉林栓皮栎林板栗林亮叶桦林。     

基于生态位分化的秦岭松栎混交林建群种共存机制

在秦岭山脉中段设置15个油松-锐齿槲栎混交林调查样地,从物种组成、生态位宽度、建群种径阶结构等方面分析了该混交林的群落学特征,并运用典范对应分析技术(CCA)探讨了环境因子(地形、土壤养分)对群落物种分布及建群种形态特征的影响,以期揭示研究区松栎混交林建群种的共存机制。结果如下:(1)15个样地共记录维管束植物139种,隶属于53科102属,油松和锐齿槲栎的建群种优势地位突出,物种丰富度较高的科分别有:蔷薇科(10属13种)、菊科(6属10种)、百合科(5属10种)和禾本科(6属6种);(2)生态位计算结果表明,油松生态位宽度(B_i=2.674)和锐齿槲栎生态位宽度(B_i=2.679)均高于其它伴生种,且二者之间的生态位重叠值极小(0.1);(3)CCA排序显示,有机质、全氮、海拔和坡度是影响混交林群落物种分布的主要生境因子;(4)两种建群树种各自的4项形态特征指标(胸径、树高、株数、冠幅面积)沿着环境梯度在CCA二维排序图中呈现出明显相反的分布格局,海拔、坡位和速效氮是形成这种格局的主导因素;(5)Godron坐标计算结果表明该混交林群落稳定性相对较高,且油松、锐齿槲栎种群的径阶结构均表现为增长型。综上所述,秦岭山地海拔、坡度、坡位和土壤氮素等生境异质性促进了油松、锐齿槲栎的生态位分化,并能维持混交林群落中这两个建群树种的长期共存。     

不同生态条件下松栎混交林3种优势乔木种群的更新规律

为探究秦岭林区松栎混交林群落乔木优势种的更新规律,通过典型样地调查,对油松(Pinus tabulifor-mis)、锐齿槲栎(Quercus aliena var.acuteserrata)和华山松(Pinus armandii)等3种优势乔木种群更新随林分密度、海拔、坡向、坡位等生态因子的变化规律进行了分析。结果表明:(1)林分密度、海拔、坡向、坡位等生态因子对3种乔木的天然更新均具显著影响;3种优势乔木树种幼苗密度均随林分密度增加而显著增加,林分密度从850株.hm-2增加到1 525株.hm-2时,3种幼树密度也逐渐增加,但林分密度为1 900株.hm-2时,3种幼树密度均显著降低;从海拔1 283m增至1 665m,锐齿槲栎和油松幼苗幼树密度均随海拔增加而显著增加,但海拔增至1 835m时,这两种幼苗幼树密度均显著降低。(2)华山松幼苗幼树密度一直随海拔升高而增加;从南偏西20°到75°,锐齿槲栎和华山松幼树密度逐渐降低,至北偏东40°(阴坡)时又显著增加,但3种乔木幼苗及油松幼树密度一直随坡向变化而增加;锐齿槲栎幼苗密度在下坡位显著高于中坡位和上坡位,但油松和华山松幼苗幼树随坡位由下到上逐渐增加。结果提示,处于中海拔、阴坡且密度适中的林分3种优势乔木更新最佳,对这类林分实施封禁将有助于松栎混交林优势乔木的天然更新。     

秦岭牛背梁植物物种多样性垂直分布格局

基于秦岭山脉中段牛背梁自然保护区南北坡垂直样带51个样方的调查资料,利用植被数量分析方法(TWINSPAN和DCA)对牛背梁植物群落进行了分类和排序,并分析了植物物种多样性沿海拔梯度的分布格局。结果表明,牛背梁的植被群落具有明显的海拔梯度格局,从低海拔到高海拔依次分布有：锐齿槲栎(Quercus aliena var.acuteserrata)林,桦木(Betula spp.)林．巴山冷杉(Abis Jargesii)林和亚高山灌丛。海拔梯度是牛背梁山区制约植物群落分布的主要因子,而坡向和坡度则起到次要作用。对物种多样性的分析表明,物种总数、木本植物物种多样性和草本植物物种多样性在南北坡具有不同的海拔梯度格局。物种总数在南坡呈现单峰分布格局,而在北坡分布趋势不明显;木本植物物种多样性在南北坡具有相似的分布格局：在低海拔沿海拔梯度变化不明显,而在高海拔则随海拔上升而急剧下降;草本植物物种多样性在南北坡沿海拔梯度变化的规律不明显。β多样性沿海拔梯度先减少后增加,形成两端高中间低的格局,说明中海拔地区生境条件较为均一,低海拔地区的人为活动增加了生境的异质性,而高海拔地区的生态过渡特性增加了物种的更替速率以及群落的相异性。     

秦岭南坡中段植物群落物种多样性与环境相关性分析

本研究为了探讨秦岭南坡中段植物群落物种多样性分布特征及其与环境的相关性,在整个研究区针对44个植物群落进行野外调查,共设置107个样地。通过利用相关性分析的方法来分析群落物种多样性与环境因子关系,结果表明:不同群落之间物种多样性存在明显差异。其中,巴山木竹(Bashania fargesii)林物种多样性相对最低,青刚栎(Cyclobalanopsis glauca)和锐齿槲栎(Quercus aliena var.acuteserrata)混交林物种多样性相对最高;同一群落各层次间仅乔木层与灌木层有显著相关性,但物种多样性的大小没有统一的顺序;地形、土壤和物种多样性存在着关联性,其中物种多样性与海拔、有效磷、土壤全钾均存在显著相关性。     

秦岭南坡松栎林群落演替过程中物种组成及多样性动态分析

为揭示秦岭南坡植物群落演替与物种多样性之间的复杂关系,采用空间代替时间的方法在秦岭南坡油松林、松栎混交林和锐齿栎林群落典型分布区域设置45个样地进行了群落学调查,统计分析了油松林→松栎混交林→锐齿栎林这一演替序列过程中草、灌、乔3层的物种组成和α物种多样性动态。结果表明:(1)秦岭南坡油松林、松栎混交林和锐齿栎林3种群落共有维管植物312种,隶属于73科183属,其中草本植物136种,灌木(含木质藤本)98种,乔木78种;油松林群落包含52科117属190种,松栎混交林群落含有60科95属129种,锐齿栎林群落则为50科109属178种。(2)沿油松林→松栎混交林→锐齿栎林群落演替序列,草本层物种均匀度和物种多样性显著降低,物种丰富度呈"V"形变化趋势;灌木层物种丰富度、均匀度以及物种多样性均无显著差异;乔木层物种多样性呈明显的单峰型变化,其中松栎混交林群落物种多样性指数最高。研究表明,秦岭南坡松栎林群落物种多样性随演替进展总体上呈现单峰型变化,与中期物种多样性假说一致;物种多样性可能仅仅是群落稳定的一个基础或前提条件。     

暖温带-北亚热带过渡区落叶阔叶林群落特征

白云山落叶阔叶林是暖温带-北亚热带生态过渡区保存较完好的植被,具有北亚热带向暖温带的过度性质,群落结构相对复杂,物种种类相对丰富。参照巴拿马巴洛科罗拉多岛(Barro Colorado Island,BCI)样地的技术规范,于2015年在白云山国家森林公园建立了一个5 hm~2固定监测样地,调查并鉴定了样地内胸径≥1 cm的木本植物。基于首次调查数据从物种组成、径级结构、重要值、群落分类和分布格局等方面进行了分析,结果表明:(1)样地共有17963株个体,隶属于34科55属93种;(2)该群落以锐齿槲栎(Quercus aliena var.acuteserrata)、华山松(Pinus armandii)、三桠乌药(Lindera obtusiloba)、漆树(Toxicodendron vernicifluum)占优势,稀有种占总种数的36.56%,偶见种占总种数的30.11%;(3)所有物种的径级结构分布呈倒"J"型,表明群落内有充足的幼苗,群落更新状况良好;(4)多元回归树经过交叉验证,以凹凸度和平均海拔将样地植被划分为3类,Ⅰ:锐齿槲栎-华山松-三桠乌药-秦岭木姜子-河南海棠群落;Ⅱ:锐齿槲栎-华山松-漆树-连翘群落;Ⅲ:锐齿槲栎-白桦-白檀-照山白群落;(5)点格局分析表明样地内优势种主要表现为聚集分布格局。研究结果有助于增加人们对暖温带-北亚热带生态过度区内森林群落的认识,为此区域内植物群落的管理和保护积累基础资料。     

河南省宝天曼锐齿槲栎林树木死亡对空间格局及种间相关性的影响

树木的死亡是森林生态系统中重要的生态学过程。为了探索树木的死亡如何影响物种的空间格局及种间相关性,并进一步探寻树木死亡的原因,运用点格局分析的相关方法,对宝天曼1 hm2固定样地内树木死亡前后17个物种的空间格局及种间相关性进行了分析。结果表明:(1)树木死亡前后物种的空间格局以聚集分布为主,但死亡后在较大尺度上表现为聚集分布的物种数减少,随机分布的物种数增多。(2)树木死亡前后物种与锐齿槲栎(Quercus aliena var.acuteserrata)的种间相关性均以正相关和不相关为主,并且死亡后,在小尺度上表现出正相关物种对数增多,负相关物种对数减少。(3)物种个体的死亡符合随机死亡假说。死亡前后仅4个物种与锐齿槲栎的种间相关性完全改变,多数物种的空间格局以及与锐齿槲栎的种间相关性仅在少数尺度上发生改变甚至没有改变,而且不同物种的变化没有明显的规律。(4)锐齿槲栎死树和13个物种活树存在显著的种间相关性,但死树活树的种间相关性与死亡前后种间相关性的变化并不完全一致。只有5个物种的活树与锐齿槲栎死树存在竞争,而且个体死亡后物种与锐齿槲栎之间竞争加剧。个体的死亡是多种因素共同作用的结果,虽然物种的死亡符合随机死亡假说,但也存在少数竞争死亡的个体。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

2017年中国植物科学若干领域重要研究进展

2017年中国植物科学继续保持高速发展态势, 重大成果频出, 具体表现在中国植物学家在国际顶级学术期刊发表的文章数量平稳上升。中国植物科学领域的研究工作者成果精彩纷呈, 如新型广谱抗病机制的发现、水稻广谱抗病遗传基础及机制和疫霉菌诱发病害成灾机制研究等。2017年中国生命科学领域十大进展评选中, 有两项植物科学领域的研究成果入选。水稻生物学、进化与基因组学和激素生物学等领域学科发展突出。另外, 值得一提的是, 长期从事高等植物与代谢途径调控分子网络研究和水稻品种设计育种的李家洋院士的研究成果“水稻高产优质性状形成的分子机理及品种设计”荣获2017年国家自然科学一等奖。这一具有重大国际影响的开创性贡献标志着中国植物科学在该领域的国际科学前沿居于引领和卓越地位。该文对2017年中国本土科学家在植物科学若干领域取得的重要研究成果进行了系统梳理, 旨在全面追踪和报道当前中国植物科学领域发展的最新前沿动态, 与广大读者共同分享我国科学家所取得的辉煌成就。     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

Changes in aquatic vegetation in Rhine floodplain streams in Alsace in relation to disturbance

Abstract. Changes are described in aquatic vegetation in oligotrophic, groundwater-fed Rhine floodplain streams in Alsace (eastern France), resulting from disturbance. Disturbance factors include changes in nutrients, either permanent ones - effluent from a waste water treatment plant or trout hatcheries - or periodic ones: flooding. Regular inputs of high levels of phosphate and ammonia modified the macrophyte vegetation in these streams. The floristic composition, which was characteristic of oligotrophic waters upstream of the eutrophicated sector, changed to that of a eutrophic situation as originally found downstream. Periodic disturbance by floods which normally occur once a year, irregularly eutrophicates the small streams, causing the development of a mixture of eutrophic and oligotrophic species. Six macrophyte communities are distinguished, indicating different trophic levels. The aquatic vegetation is adapted to the variations of phosphate and ammonia levels. Hence, aquatic macrophytes can be used as bio-indicators of fluctuations in water nutrient levels in relation to the type of disturbance.     

Morphine-potentiated platelet aggregation in in vitro and platelet plug formation in in vivo experiments

The detailed mechanisms underlying morphine-signaling pathways in platelets remain obscure. Therefore, we systematically examined the influence of morphine on washed human platelets. In this study, washed human platelet suspensions were used for in vitro studies. Furthermore, platelet thrombus formation induced by irradiation of mesenteric venules with filtered light in mice pretreated with fluorescein sodium was used for an in vivo thrombotic study. Morphine concentration dependently (0.6, 1, and 5 microM) potentiated platelet aggregation and the ATP release reaction stimulated by agonists (i.e., collagen and U46619) in washed human platelets. Yohimbine (0.1 microM), a specific alpha(2)-adrenoceptor antagonist, markedly abolished the potentiation of morphine in platelet aggregation stimulated by agonists. Morphine also potentiated phosphoinositide breakdown and intracellular Ca(2+) mobilization in human platelets stimulated by collagen (1 microg/ml). Moreover, morphine (0.6-5 microM) markedly inhibited prostaglandin E(1) (10 microM)-induced cyclic AMP formation in human platelets, while yohimbine (0.1 microM) significantly reversed the inhibition of cyclic AMP by morphine (0.6 and 1 microM) in this study. The thrombin-evoked increase in pH(i) was markedly potentiated in the presence of morphine (1 and 5 microM). Morphine (2 and 5 mg/g) significantly shortened the time require to induce platelet plug formation in mesenteric venules. We concluded that morphine may exert its potentiation in platelet aggregation by binding to alpha(2)-adrenoceptors in human platelets, with a resulting inhibition of adenylate cyclase, thereby reducing intracellular cyclic AMP formation followed by increased activation of phospholipase C and the Na(+)/H(+) exchanger. This leads to increased intracellular Ca(2+) mobilization, and finally potentiation of platelet aggregation and of the ATP release reaction.     

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations. Apoptosis was first noted 6 h after the onset of ischemia with its highest value occurring after 72 h. Apoptotic nuclei were absent in remote areas of the left and right ventricles. Apoptotic nuclei within the infarcted area showed diminished intensity of Ho342 fluorescence. Three days after ischemia, a border zone adjacent to the infarcted area consisting of apoptotic macrophages was recognized. A novel finding was the appearance of apoptotic cardiomyocytes in the isolated perfused ischemic heart. Occurring as early as 50 min after the onset of ischemia, a high apoptotic index was present adjacent to the ligature placed around the coronary artery. This observation provides the opportunity to selectively examine factors leading to apoptosis in the ischemic heart under controlled experimental conditions.