编辑选编

气候变化下苔原和稀树草原生物群落木本植物入侵加剧 随着全球变化,全球生物群落正在发生变化。那些受到温度或降水限制的生物群落,如苔原和稀树草原,对于气候变化的强烈影响可能更为敏感。尽管木本植物入侵在两个生物群落中都很普遍,但其与温度和降水变化的关系仍然未知。     

昆明市花粉过敏症预报试验

通过对昆明城区和郊区2000-2001年花粉观测资料的分析,发现一年中花粉浓度有明显的周期性和季节性。分析了气象要素与空气中飘移花粉的相关关系。在此基础上,利用统计方法,找出了与花粉过敏症相关好的气象因子,建立了花粉过敏症的预报方程;应用医院花粉过敏症的发病率进行验证,同时利用气温、风速、相对湿度对预报值加以订正,使预报结果更接近实际。     

张北细石器文化遗物的地层特征及其意义

1文化遗物在1：5万区域地质调查过程中,于河北省张北—沽源一带发现20余处细石器文化遗存,采集方制品千余件。以细石器制品为主,主要为细石核16件、细石叶74件、箭头55件、刮削器83件、尖状器24件,雕刻器3件、标枪头2件、普通石片733件,除此尚见粗大石器12件、骨器1件及许多半石化的动物牙齿化石。细石器加工精细,器形匀称、现整,用指垫法和压制法加工。     

天津气传花粉预测模型研究

使用1999～2004年3～10月天津市河西区铁塔花粉监测数据和同地点的气候观测站(54517)气象资料,进行了天津市72h气传花粉浓度预测模型研究。设计了全花粉季、分季节(春、夏、秋)、分阶段的3种不同预测方案,利用多元线性和非线性回归技术分别建立了花粉预测模型,并对各个方案及预测模型进行了对比分析。结果发现,除夏季以外,多元非线性预测模型优于多元线性回归预测模型,分阶段预测方案优于全花粉季和分季节预测方案,且预测准确率也随之提高。     

鸡西群城子河组时代的进一步探讨

近年来 ,古生物工作者在鸡西群城子河组及其相当地层的生物化石研究方面取得了巨大的进展。在总结这些新的材料的基础上 ,通过与国外的化石组合进行对比 ,从海相双壳类、植物、孢粉及海相沟鞭藻化石等多方面的证据 ,尤其是根据 Thracia rotundata、Vectianella、Pseudaphrodina ricordeana等欧洲 Aptian阶重要的双壳类化石、被子植物及三沟类被子植物花粉的出现 ,城子河组的时代应为 Aptian期 - Albian期早期     

神农架北坡表土常见花粉的R值研究

根据表土孢粉分析和植被样方调查的比较研究，获得了神农架北坡表土常见花粉的R值，常绿阔叶树花粉一般具有较低代表性，R值变化于0．70左右，绝大部分落叶阔叶树花粉也具有较低代表性，R值变化于0．68－0．88之间，但桦，桤木和槭却表现异常，针叶树有气囊花粉具有明显的超代表性，R值变化在1．35－2．44之间，松表现最为强烈，草本植物花粉的R值变化较大，代表性较差，影响R值的因素很多，植物的生态特性，花粉特征，花粉源距离，花粉产量，地形等作用尤为明显。     

碱性环境对油松花粉保存影响实验研究

孢粉是恢复古植被、古气候的重要代用指标。然而,即使是同一时代的地层,不同地点、不同岩性提取出的花粉量差异很大,造成这些差异的原因很多,其中花粉在不同沉积环境中的保存差异是重要原因之一。本研究是在实验室内模拟自然条件下碱性环境对油松花粉(Pinus tabulaeform is)的破坏情况:煮水5小时,泡10%NaOH溶液10天,煮10%NaOH溶液5小时对油松花粉破坏都很小;煮20%和30%NaOH溶液1小时对油松花粉影响也不明显;煮40%NaOH溶液1小时,油松花粉壁出现蚀变,加热时间增至5小时,蚀变现象进一步加深。表明油松花粉具有很强的耐碱,耐高温能力。更强碱或更长时间情况下花粉蚀变情况,有待进一步研究。     

Effects of topography and land use on woody plant species composition and beta diversity in an arid Trans-Himalayan landscape,Nepal

Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only（Pisang site） while the other pair has clear differences in land use in addition to slope exposure（Braka site）. In each site, we sampled 72 plots（36 on each slope） in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis（CA） results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables（e.g., radiation index） affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Br     

The decreasing spring frost risks during the flowering period for woody plants in temperate area of eastern China over past 50 years

The temperate monsoon area of China is an important agricultural region but late spring frosts have frequently caused significant damage to plants there. Based on phenological data derived from the Chinese Phenological Observation Network （CPON）, corresponding meteorological data from 12 study sites and phenological modeling, changes in flowering times of multiple woody plants and the frequency of frost occurrence were analyzed. Through these analyses, frost risk during the flowering period at each site was estimated. Results of these estimates suggested that first flowering dates （FFD） in the study area advanced significantly from 1963 to 2009 at an average rate of -1.52 days/decade in North-east China （P〈0.01） and -2.22 days/decade （P〈0.01） in North China. Over the same period, the number of frost days in spring decreased and the last frost days advanced across the study area. Considering both flowering phenology and occurrence of frost, the frost risk index, which measures the percentage of species exposed to frost during the flowering period in spring, exhibited a decreasing trend of -0.37% per decade （insignificant） in Northeast China and -1.80% per decade （P〈0.01） in North China, implying that frost risk has reduced over the past half century. These conclusions provide important information to agriculture and forest managers in devising frost protection schemes in the region.