Functional identity of overstorey tree height and understorey conservative traits drive aboveground biomass in a subtropical forest

The niche complementarity hypothesis has received empirical support but species differ in functional strategies for their contribution to ecosystem function, as predicted by the mass ratio hypothesis. Our understanding of how functional identity of conservative and acquisitive strategies of trees predicts aboveground biomass across forest strata (i.e. overstorey and understorey) remains unclear. Aboveground biomass, community-weighted mean (CWM − functional identity) of trait values (6 leaf and 2 stem traits), and soil physicochemical properties were estimated for 125 plots in a 5-ha subtropical forest in Eastern China. We used multiple linear regressions models to relate aboveground biomass to CWM indices at overstorey and understorey strata separately, and whole-community level. We finally employed the structural equation model to test for the effects of overstorey on understorey strata, in addition to the effects of soil physicochemical properties. Forest strata optimal models showed that overstorey strata had high aboveground biomass when they are dominated by functional identity of tree height, whereas high aboveground biomass in understorey strata was driven by functional identity of dense-wooded conservative strategy. Whole-community optimal model showed that communities dominated by functional identity of leaf dry matter content and mean leaf area had high aboveground biomass. Aboveground biomass was negatively related to soil nutrients across forest strata and whole-community level. The structural equation model showed that CWM of overstorey tree height did not affect understorey functional identity and aboveground biomass, when soil physicochemical properties were accounted. Soil nutrients had positive effect on functional identity of overstorey tree height whereas negative effect on functional identity of understorey dense-wooded strategy. This study highlights the fundamental roles of forest strata where overstorey and understorey strata contribute to their corresponding aboveground biomass with contrasting functional strategies across a range of soil nutrients. High aboveground biomass was potentially driven by functional identity of tree height through making use of plentiful soil nutrients at overstorey strata, whereas by conservative strategy at understorey strata through enduring nutrient-poor soils. To better understand the roles of functional identity of conservative and acquisitive strategies in driving ecosystem functions, it is worth to analyse forest strata separately.     

伊朗卡尚地区古近纪介形类的发现

本文简要报道了发现于伊朗卡尚地区古近系的介形类,计16属6种、8比较种、9未定种及1亲近种。根据介形类化石组合面貌,并结合钙质超微、沟鞭藻和有孔虫化石组合,认为含介形类化石的地层时代为始新世至渐新世,推测其沉积环境为正常浅海大陆架环境,而且为温暖浅海内陆架。     

Biogenic chaos: Cryptobioturbation and the work of sedimentologically friendly organisms

Biogenic chaos, from an ichnological point of view, can be defined as total bioturbation of sediment by infaunal organisms, such that the original sedimentary fabric and associated sedimentary structures are entirely destroyed. The truth, however, is that not all forms of thorough bioturbation are purely destructive. As improbable as it initially sounds, sediment can be pervasively (potentially 100%) bioturbated, and yet have suffered remarkably little distortion of the original bedding. In nature there exist many different levels of organism communities. Historically, the study of any natural system begins with the most obvious, attention-grabbing elements. Only later do the more innocuous aspects come to be discovered and appreciated. Ichnology shows a similar historical pattern. The most obvious aspects of the science, the discrete burrow or track forms, have been well studied for many years. Only recently have more subtle biogenic disturbances, such as micro borings, bacterial trails, meiofaunal burrows, infaunal tiering, etc., gained attention. Likewise, another level of bioturbation – cryptobioturbation – exists and is becoming more evident in the rock record. Owing to its diminutive and obscure nature, cryptobioturbation has not received widespread attention. As the name implies, cryptobioturbation is characteristically small in scale and exceedingly subtle in expression. What sets it apart from other forms of bioturbation, however is its tendency to preserve rather than to destroy the sediment’s primary physical structure.The fabric that results from cryptobioturbation can have significant influence on resulting permeability and porosity trends. In some systems where both cryptically bioturbated sandstone and generally unburrowed sandstone are present, mini-permeameter measurements show that numerous heterogeneities are retained in the unburrowed sandstone, resulting in a wide range of permeabilities. In contrast, cryptically bioturbated sandstone intervals show that these heterogeneities are less pronounced, and the resulting permeability curve is more uniform. The effect of cryptobioturbation does not result in enhanced permeabilities, but rather diminishes internal heterogeneities, leading to a more uniform permeability distribution.     

Biostratigraphy and sedimentary evolution of Late Miocene and Pliocene continental deposits of the Granada Basin (southern Spain)

The Late Miocene and Pliocene continental sediments in the Granada Basin (southern Spain) have yielded large amounts of fossil small mammals in 37 localities from 11 sections. The aim of this paper is to integrate faunistic, stratigraphic, and sedimentary criteria to unravel the geological history of the continental infilling of the basin. The palaeontological study has led to a detailed biozonation on the basis of rodents, which helps to correlate in detail the different sedimentary units found in the basin, and to follow the changes of the different sedimentary systems and their palaeogeographical evolution through time. Combination of the proposed biostratigraphy and the reinterpretation of the magnetostratigraphic analyses of the Barranco del Purcal section allows us to assign an absolute age slightly older than 5.23 Ma to the Turolian–Ruscinian boundary (MN13‐MN14).     

中国西南地区古生代放射虫硅岩地层——一个潜在的油气勘探目标

古生代放射虫硅岩地层中富含浮游相的微体生物化石,这些化石中的脂类物质和有机质在地层中往往形成海相烃源岩而富含油气资源。这类地层的油田已在北极加拿大、美国、澳大利亚和俄罗斯等地发现,特别是俄罗斯的Domanik层(上泥盆统)是目前正在开采的世界上最有名的顶级大油田。我国西南地区的云南、贵州和广西等省区有与世界级大油田相似的古生代放射虫硅岩地层,但在过去的勘探中这类地层从未列入勘探目标,我们相信,在不久的将来,这类地层将成为一个潜在的油气勘探目标。     

江苏太滆地区晚更新世以来古生物群及环境

本文重点研究江苏武进市南部太（湖）（湖）地区ＺＫ０１、ＺＫ０２、ＺＫ０３和ＺＫ０４孔海侵层微体古生物有孔虫、介形类、钙质超微化石组合和双壳类、腹足类等大化石的地层分布,丰度、分异度的变化和生态环境特征,结合沉积物结构分析和１４Ｃ年龄测定,证实晚更新世以来本地区经历了太湖海侵、湖海侵和镇江海侵,较全面地论证了每次海侵影响范围和沉积环境类型。其中湖海侵分布面积最大,高峰期可能波及卜弋周围,微体化石丰富,有孔虫组合中出现浮游型种类,反映了开放性海湾环境;太湖海侵范围限于卢家巷—马杭一线以南,化石较少,时有淡水种类出现,代表边滩泻湖—半封闭海湾环境;镇江海侵层仅见于卜弋ＺＫ０１孔,化石稀少,沉积物以亚砂土、亚粘土为主,是潮间带－潮坪相的产物     

南海莺琼盆地沉积环境中几种厌氧细菌的组成与分布

在严格的厌氧条件下,用MPN计数的方法测定了莺琼盆地东方1-1-1井垂直剖面不同沉积层的地质样品中的硫酸盐还原菌、发酵细菌的数量,并检测了产甲烷细菌,对各种菌的形态进行了观察,比较了菌数量与一些指标的关系,并对产甲烷细菌的代谢类型和产甲烷能力进行了观察。研究结果表明：硫酸盐还原菌在各样品中均存在,与沉积深度无相关性,而与样品中SO2-4的含量有一定相关性;而发酵细菌的分布也与沉积深度无相关性,而与样品中的有机质有一定的负相关性。全部样品中均检测出两种形态产甲烷细菌,即甲烷球菌（Methanococcus）和甲烷杆菌（Methanobacterium）,其营养类型为H2／CO2。     

Groundwater flow pattern in the vicinity of a salt lake

A numerical model was used to visualize and investigate density-driven flow in the subsurface arising in the vicinity of salt lakes, where saline fluid from the lake meets fresh groundwater. Typical flow patterns are determined for a relevant range of the dimensionless parameters Ra and Co, showing that the Rayleigh-number Ra is the relevant parameter for the emergence of density-driven flow, while the influence of the Co-number is small.