Phylogeny, diet, and habitat of an extinct ground sloth from Cuchillo Curá, Neuquén Province, southwest Argentina

Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.     

祁连山海北高寒草甸地区紫外辐射特征及其对植物生理作用的探讨

利用祁连山海北高寒草甸地区 2 0 0 0年植物生长期内的太阳辐射观测资料 ,分析了该地区太阳紫外辐射 (UV)在植物生长期内的日、季节变化特征 ,以及在太阳总辐射 (Eg)中所占的比例 (η)。结果表明 :海北站地区UV较强 ,瞬时极大值可达 77W·m-2 ,日总量最大达 1.8MJ·m-2 以上 ;实际天气状况下月总量最大可达 4 1.6 2 0MJ·m-2 (5月 ) ,植物生长期内的 4月到 10月总量达 2 18.6 5 1MJ·m-2 。UV有明显的日、季节变化规律。日间UV所表现的单峰式曲线变化过程 ,与总辐射变化有关。在晴天状况下 ,η的变化下午高于上午 ,日平均约为 0 .0 4 8;阴天状况下在 13:0 0～ 14 :0 0较高 ,早晚低 ,且随云层厚薄而发生显著的变化。同时表明 ,阴天状况下的η值 (0 .0 5 3)高于晴天。就生长期实际情况来看 ,η值在植物生长的前期较高 ,植物生长后期较低 ,植物生长期内平均约为 0 .0 5 2。受强UV的影响 ,高寒草甸几种主要植物 ,其植物根、茎、叶的可溶性糖含量、淀粉含量、非结构性碳水化合物均较高 ,且表现出日出后迅速增加 ,植物根茎粗壮等 ,植物的生理适应性及其植物体的结构发生改变 ,致使高寒草甸植物具有明显的抗寒性功能机制和形态结构。     

植物生理学与地球物理学的结合点

介绍了含羞草在台风前及榉树、枫树、山茶、月桂等树木生物电位在地震前的异常变化 ,指出了植物生理电位与地震前兆现象之间存在的相关关系 ,找到了植物生理学与地球物理学的结合点     

怒江峡谷区植物资源及其评价

怒江峡谷特殊的自然地理环境和立体气候,孕育出种类丰富的植物资源,新老、珍稀、孑遗和特有种兼备。有维管束植物185科878属3138种(包括亚种和变种),其中蕨类植物41科101属374种,裸子植物5科12属22种,被子植物139科765属2742种。峡谷区科属种分类分别占云南同类植物的56.74％、40.46％和20.79％,占横断山区的84.47％、59.95％和36.66％;植物区系成分复杂多样,各类热带分布属(不含世界分布,下同)352个,占峡谷区总属数的45.30％;各类温带分布属346个,占峡谷区总属数的44.53％;地中海或泛地中海分布仅16属,占峡谷总属数的2.05％;中国特有属17个,占峡谷区总属数的2.18％。近期有开发前景的植物资源种类多,且门类齐全,是当地各民族脱贫致富,建设家乡的宝贵财富。立足植物资源,面向市场,以科学技术为先导,大力发展名特中药材、多维果类、油料植物、花卉和食用菌等,形成名、特产品,参加国内外市场竞争。建议成立生物资源开发领导机构,建立生物产品生产基地和加工工业,进行集约化生产,重视和加强科学技术和教育投入,制订有关生物资源开发的优惠或特殊政策。     

Karstification at Beşkonak dam site and reservoir area,southern Turkey

Bekonak dam and hydroelectric power plant are planned to be constructed on the Köprüçay river, 40 km east of the Antalya city. In the dam site and reservoir area, Köprüçay Conglomerates of Miocene age and the Bekonak Formation (sandstone-claystone) alternating with each other crop out vertically. Köprüçay conglomerates, with the components of limestone fragments and carbonate texture, are karstic and permeable, whereas the Bekonak Formation is impermeable. At the northern edge of the reservoir area, the Olukköprü karst springs discharge at a minimum of 30 m³/s. These springs discharge mainly through vertical and subvertical joint systems. Intensive superficial karstification developed along the joint systems and the terrane reveals columns of rocks, called fairy chimneys. Olukköprü springs represent the discharge point for a large and continuous system of underground solution cavities. In the Köprüçay basin, there are numerous karstic features within the conglomerates. Within the reservoir area, Kuruköprü cave, with a length of 530 m, is an example of these caves developed within the conglomerates. In some parts of the reservoir area, where the groundwater level is lower than the surface-river elevation, a highly developed karstification zone is present within the fluctuation range of groundwater between depths of 40 and 50 m. The above-mentioned Kuruköprü cave is an active cave developed in the dam site and its vicinity. The solution conduits developed along the system of mostly vertical fractures and joints are interconnected, thus giving rise to a three-dimensional conduit network. On the other hand, a majority of these conduits have clay and calcite filling materials. Karstification in the dam site varies with depth exponentially. Data suggest that karstification has a vertical extention as deep as –220 m.     

土壤盐分特征对内陆盐沼盐生植物群落的影响

为研究内陆盐沼植物群落的分布对土壤盐分的响应特征,选取鄂尔多斯盐湖盐沼区作为研究区,筛选了肉质耐盐植物群落,苔草植物群落和禾草植物群落3类典型植物群落,开展了土壤含水量、pH、电导率以及Na_⁺,K_⁺,Mg2_⁺,Ca_{^{2 +}},Cl_^-、SO_4^2-、CO_3^2-和HCO_3^-的测定,分析了区内典型植物群落对土壤水盐因子的响应规律。探讨了3类植物群落之间土壤因子含量的差异性;采用相关性分析和CCA分析,评价了3类植物群落多样性及物种分布随土壤因子的变化规律。结果表明,区内3类植物群落中,土壤盐分含量表现为肉质耐盐植物群落最高,苔草植物群落最低,禾草植物群落居中;植物多样性与土壤中含量最高的Na_⁺和SO_4^2-的相关性最显著;植物分布同时受到土壤盐分、水分和pH的显著影响。研究结果可为鄂尔多斯盐湖区土壤盐渍化改良和植被恢复提供理论支撑。     

Modelling of groundwater–vegetation interactions in a tidal marsh

Wetting and drying due to tidal fluctuations affect soil conditions and hence plant growth in tidal marshes. Here, a coupled one-dimensional model was developed to simulate interacting groundwater flow and plant growth in these wetlands. The simulation results revealed three characteristic zones of soil conditions for plant growth along a cross-creek section subjected to the combined influences of spring-neap tides and evapotranspiration: (1) a near-creek zone affected by semi-diurnal tides over the whole spring-neap cycle, where the soil is well aerated although the plant growth could be slightly limited by the local water content dropping periodically below the wilting point on the ebb tide; (2) a less well-drained zone where drainage occurs only during neap tides (for which the daily inundation is absent) and plant growth is aeration-limited; and (3) an interior zone where evapotranspiration determines the soil–water saturation. Plant growth dynamics, which depend on these soil conditions, lead to spatial biomass distributions that are consistent with the characteristic zonation. The simulations shed light on the feedback mechanism for groundwater–vegetation interactions in the marsh system. It was demonstrated that the growth of pioneer plants can improve the soil aeration condition as a result of transpiration. The strength of this feedback varies spatially in accordance with the three characteristic zones of soil–water saturation. However, the development of another species in the marsh system is likely to be more complicated than suggested by the “positive feedback” mechanism proposed previously, due to the influence of inter-species competition. The feedback effects are generally more complex, involving both plant growth enhancement and inhibition depending on the combined influence of the intra- and inter-species competition, the ecosystem’s carrying capacity and plant transpiration. These findings demonstrate the interplay of ecological and hydrological processes in tidal marshes, and provide guidance for future research, including field investigations that aim to establish the principle relationship between marsh morphology and plant zonation.     

Influence of stock origin and environmental conditions on the survival and growth of juvenile freshwater pearl mussels (Margaritifera margaritifera) in a cross-exposure experiment

The freshwater pearl mussel (Margaritifera margaritifera) is a highly specialized and sensitive freshwater bivalve, whose survival in the juvenile phase is indicative of high quality habitats. This contribution investigates the use of juvenile freshwater pearl mussels as bioindicators, considering the influence of mussel stock and study stream conditions on juvenile performance, as described by survival and growth rates. A standardized cross experiment was carried out investigating juvenile performance in four different pearl mussel stocks originating from the Rhine, Danube and Elbe drainages, representing distinct genetic conservation units. The juveniles were exposed in five study streams which were selected to integrate pearl mussel streams with different water qualities and recruitment status of the mussel population. Per study stream, five standard mesh cages containing an equal number of 20 (10 × 2) juvenile pearl mussels per stock in separate chambers were installed. Survival and growth rates of juveniles were checked after three months (i.e. before their first winter) and after nine months (i.e. after their first winter). Mussel stock and study stream conditions significantly influenced juvenile performance. Growth rates were determined by study stream conditions and increased with stream water temperature, organic carbon and C/N ratios. Survival rates varied stock-specifically, indicating different levels of local adaptation to their native streams. Due to the detection of stream-specific differences in juvenile performance, freshwater pearl mussels appear suitable as bioindicators. However, a careful consideration of stock-specificity is necessary to avoid false interpretation of bioindication results. The comparison of stock-specific survival in native versus non-native streams implicates that exposure of juveniles outside their native habitats is able to increase breeding success or else serve for risk spreading in breeding programs.