二郎山小型兽类区系及分布格局

动物种类和数量在不同的山地或同一山地的不同垂直高度有很大的差异,正因如此,国际上和国内的研究者们一直在努力探讨动物在山地的分布规律和产生差异的原因(Merriam et al.,1890;鲍毅新等,1984;Heaney,2001;Rickart,2001;SánchezCordero,2001;张云智等,2002;李义明等,2003;马俊等,2010).横断山是中国最长、最宽和最典型的南北向山系,位于青藏高原东南部,通常为四川、云南两省西部和西藏自治区东部南北向山脉的总称.横断山是全球25个生物多样性热点地区之一,其生物多样性资源极其丰富(Myers et al.,2000).     

青藓科中国新记录种——短尖拟青藓

该文报道了短尖拟青藓［Sciuro-hypnum ornellanum (Molendo) Ignatov & Huttunen］在新疆阿尔泰山的分布,这是该种在中国的首次记录。详细介绍了拟青藓属［Sciuro-hypnum （Hampe） Hampe］的由来,讨论了短尖拟青藓的形态特征及其地理分布,对其与形态相近种进行了比较分析,并提供了中国拟青藓属分种检索表。该种的发现不仅为中国青藓科植物研究提供了新资料,同时也进一步佐证了中国新疆植物区系与俄罗斯、中亚及欧洲的密切联系。     

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.     

秦岭南坡油松-锐齿槲栎混交林群落不同层次多样性特征及环境解释

在秦岭山脉南坡陕西省境内设置11个样地进行实地调查,从植物物种组成、多样性指数差异以及多样性指数沿环境梯度排序等方面对该区域油松-锐齿槲栎天然混交林的群落总体以及乔木层、灌木层、草本层的各自4个α多样性指数（Patrick丰富度指数、Simpson优势度指数、Shannon-Wiener多样性指数、Pielou均匀度指数）特征进行分析,以揭示该群落多样性特征及其与环境因素的关系。结果显示：（1）11个样地共记录维管束植物112种,隶属于45科77属,分布较广的物种有蔷薇科、菊科、百合科、松科、禾本科和忍冬科。（2）研究区群落中建群种锐齿槲栎和油松的优势地位突出,乔木层伴生种稀少,平均仅为4.8种,多样性水平较低;灌木层物种组成丰富,平均11.4种;草本层次之,平均9种。（3）单因素方差分析表明,该群落不同层次的多样性指数之间均存在极显著差异（P<0.01）;LSD多重比较及多样性指数变化趋势分析表明,群落多样性水平表现为总体>灌木层>草本层>乔木层。（4）CCA法将群落不同层次多样性指数沿地形因子和土壤养分等12项环境指标梯度的分布划分为界线明显的3个区域,即Ⅰ区（中等浓度土壤磷素和有机质制约区）、Ⅱ区（非环境因子制约区）和Ⅲ区（高浓度土壤磷素制约区）;群落总体多样性主要受灌木层影响,同时也受乔木层均匀度影响,但环境因子对乔木层多样性基本无限制性作用。（5）土壤速效磷、全磷和有机质是造成研究区群落不同层次多样性差异的主要因素,海拔、坡向等地形因子对群落多样性影响不大,可能是由于土壤养分的直接影响削弱了地形因子的间接性生态作用。研究表明：保持中等水平的土壤速效磷（3.775±1.529 mg·kg^-1）和有机质含量［（4.079±1.001）%］,并通过合理补植松栎幼树和伐除枯死木等抚育手段提高乔木层均匀度是维持秦岭南坡油松-锐齿槲栎混交林群落生物多样性的有效措施。     

Green algae from the Lower Cretaceous carbonate of northern Shiraz (Zagros Mountains,SW Iran)

In northern Shiraz (SW Iran), Lower Cretaceous carbonate was studied in detail. In this study, nine species of dasycladacea algae were classified. There are different species of dasycladacea algae which belong to seven different genera: Actinoporella, Cylindroporella, Dissocladela, Heteroporella, Neomeris, Salpingoporella, Trinocladus; one species of udoteaceae belongs to Bouenia; one species of acetabulariaceae belongs to Clypeina and the microproblematicum Coptocampylodon was also seen. Among the green algae, dasycladaceae and acetabulariceae are the most frequent and udoteaceans are rare in Zagros Mountains. The genus of Trinocladus is a new record for Lower Cretaceous (Upper Albian) in SW Iran.     

啮齿动物对不同大小和种皮特征种子的取食和搬运

在宁夏六盘山区的辽东栎灌丛,以不同大小的辽东栎种子、野李和华山松种子为材料,研究了种子大小和种皮特征对啮齿动物取食和搬运行为的影响.结果表明:辽东栎小种子和华山松种子的就地取食率均显著高于辽东栎大种子和野李种子;具有厚而坚硬种皮(内果皮)的野李种子被啮齿动物搬运后的取食率和贮藏率均最高.辽东栎大种子被啮齿动物搬运后取食的距离最大(3.10 m),被搬运后贮藏的距离(6.48 m)显著大于其他类型种子.除野李种子外,其他3种类型种子的单个种子取食点都在80％以上,所有种子的单个种子贮藏点都在90％以上,含2个以上种子的取食点和贮藏点较少.较高比例的华山松种子在灌丛基部和洞穴以外的其他环境被取食,其他3种类型种子被啮齿动物搬运后主要集中在灌丛基部和洞穴中取食;种皮(内果皮)厚而坚硬的种子以土壤埋藏方式贮藏的比例偏高.     

贺兰山不同海拔典型植被带土壤微生物多样性

土壤微生物多样性在海拔梯度的分布格局研究近年来受到和植物动物一样的重视程度,但是干旱风沙区微生物多样性在海拔梯度上的多样性分布规律尚未揭示。本研究以处于干旱风沙区的贺兰山不同海拔的六个典型植被带（荒漠草原带、山地旱生灌丛带、温性针叶林带、针阔混交林带、寒温性针叶林带和亚高山草甸带）土壤为研究对象,利用Biolog微平板法和磷脂脂肪酸甲酯法(FAMEs)系统研究微生物多样性群落特征以及在不同植被带分布规律。结果表明：土壤微生物功能多样性随海拔增加发生变化,且微生物群落结构存在显著差异。Biolog分析显示土壤微生物群落代谢活性依次是：亚高山草甸>寒温性针叶林>针阔混交林>温性针叶林>山地旱生灌丛>荒漠草原,随海拔的升高土壤微生物群落物种丰富度指数（H）和均匀度指数（E）总体上均表现出增大的趋势,差异显著（P＜0.05）;FAMEs分析表明不同海拔的微生物区系发生了一定程度的变化,寒温性针叶林土壤微生物磷酸脂肪酸生物标记的数量和种类均最高,且细菌、真菌特征脂肪酸相对含量也最高;土壤微生物群落结构多样性次序是：寒温性针叶林带>针阔混交林带>温性针叶林带>亚高山草甸>山地旱生灌丛>荒漠草原。本研究结果表明贺兰山海拔梯度的微生物多样性分布规律不同于已有的植物多样性“中部膨胀”研究结果,这说明在高海拔地区有更多的适合该生境的微生物存在,这对维持干旱风沙区的生态系统功能稳定性具有重要意义。     

Tree recruitment at the treeline across the Continental Divide in the Northern Rocky Mountains,USA: the role of spring snow and autumn climate

ABSTRACT

Background: Topoclimate can influence tree establishment within treeline ecotones. Yet much less is known about how regional topography, such as the Continental Divide, Rocky Mountains, mediates the role of climate in governing treeline dynamics.

Aims: To utilise the Continental Divide to test whether contrasts in growing-season moisture regimes to the west (summer-dry) and east (summer-wet) impact the spatio-temporal patterns of tree establishment and rates of treeline advance in the Northern Rocky Mountains.

Methods: We sampled trees at sites on north- and south-facing slopes, west and east of the Continental Divide. We used dendroecological techniques to reconstruct patterns of tree establishment. Age-structure data were quantitatively compared with climate to evaluate possible mechanistic linkages.

Results: Across all sites, 96% of trees established after 1950. There was a treeline advance (range = 39–140 m) accompanied by increases in tree density. Significantly more trees established during wet springs on both sides of the Divide.

Conclusions: Overall, snow duration in spring and autumn temperatures appear to influence patterns of tree recruitment at the treeline. Continued warming will likely amplify the role of autumn climate in regulating tree establishment throughout treeline ecotones in the Northern Rocky Mountains, particularly west of the Divide where summer-dry conditions persist.     

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae,Senecioneae) along an altitudinal gradient in Harz National Park (Germany)

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae, Senecioneae) was studied in a hybrid zone on the southern slopes of Mt Brocken (Harz Mountains, Germany). A total of 415 plants representing 10 stands along an altitudinal gradient were investigated using multivariate statistical analyses of morphological characters and molecular markers (random amplified polymorphic DNA[RAPD]). Both types of traits detected pure S. hercynicus stands on the summit plateau, pure S. ovatus stands at the lowest elevations, and hybrid swarms at intermediate elevations. While morphological and molecular patterns coincided, some individuals in hybrid stands combined morphological patterns typical of S. ovatus with RAPD patterns typical of S. hercynicus, and vice versa. In general, introgression was symmetrical within stands, though one stand combined S. ovatus characters with the glandular hair typical for S. hercynicus, and two stands combined a S. hercynicus typical RAPD genotype with morphological characters shifted towards S. ovatus. Because pure stands of S. hercynicus occurred only on the summit plateau of Mt Brocken, and markers typical for S. ovatus were detectable in stands up to 1040 m a.s.l., future fusion or assimilation of the rare form, S. hercynicus, by the more widespread S. ovatus appears possible at Mt Brocken.