厦门地区的有害外来植物

本文较系统地报道厦门地区有害外来植物30科53属63种,指出其原产地和生活型,分析其为害对象和危害程度,重点介绍其中对厦门地区危害较大的12种,并提出预防和控制有害外来植物的设想和方法。     

三峡库区消落带土壤水分变化条件下池杉幼苗光合生理响应的模拟研究

三峡水库为了长期保持绝大部分有效库容, 采取/ 冬蓄夏排0的水库运行方式。在每年汛期(6-9 月), 将库区水位降至 145m; 而在汛期后, 将库区水位升至 175m。这种水库调度方式, 使得水位落差达 30m, 由此形成的消落带长度在2000km 以上, 面积达 298km2 1。三峡库区因水位周期性常年变化, 使得消落带土壤含水量呈现出一年中从干旱状态到全水淹状态的一系列梯度性变化, 由此引起对消落带植被体系的建设和保护难度加大。消落带土壤含水量的这种梯度性变化 势必 影响 到适 生造 林 树种 池杉 ( Taxodium ascendensBrongn.) 的生长发育及其生理生态学特性, 尤其是该树种的光合特性。国内外对池杉树种已经开展了一些研究, 主要集中在生物学特性2、 生长量和产量 3、 造林密度 4、 木材物理学性质5等方面, 但缺乏从生理生态学角度对池杉树种更深层次生命机理的认识。对于不同土壤水分条件特别是三峡库区消落带土壤水分变化条件下池杉树种的光合生理生态学特性却鲜有报道。       

前期水淹对牛鞭草后期干旱胁迫光合生理响应的影响

水淹和干旱是限制植物生长的两种主要环境因子。三峡库区消落带由于其特殊的地形条件和人工水文节律,呈现以年度为周期的“水淹-落干”交替变化的水文变动特征,在消落带生长的植物因此受到水淹和干旱交替胁迫的双重影响。为了探究库区蓄水对消落带植被干旱耐受性的影响,以当年生牛鞭草扦插苗为试验对象,设置对照组(CK)、表土水淹组(SF)、全淹组(TF)、对照-干旱组(CD)、表土水淹-干旱组(SFD)、全淹-干旱组(TFD)6个处理组,研究不同水分处理对牛鞭草光合特性的影响。结果表明:(1)水淹和干旱胁迫均对牛鞭草光合特性造成显著影响;(2)水淹胁迫阶段,与CK组相比,牛鞭草SF和TF组净光合速率、气孔限制值和水分利用效率显著下降,胞间CO_2浓度显著上升;(3)干旱胁迫阶段,牛鞭草CD和SFD组净光合速率、气孔导度、胞间CO_2浓度和蒸腾速率等光合参数显著低于CK组,TFD组净光合速率、气孔导度、胞间CO_2浓度和蒸腾速率等指标与CK组无显著差异;(4)复水阶段,各处理组净光合速率、气孔导度、胞间CO_2浓度和蒸腾速率等指标均与CK组无显著差异。研究表明,前期水淹并未增加牛鞭草对后期干旱胁迫的敏感性,牛鞭草对水淹和干旱胁迫均具有较好的耐受性,有助于牛鞭草对库区消落带生境变化的适应性。     

第二松花江下游稻田土壤重金属含量特征及来源分析

于2008年秋季,在长期引用第二松花江（二松）江水进行灌溉的前郭灌区,采集了具有不同灌溉历史的稻田耕层土壤样品65个,测定了土壤中7种重金属含量,分析重金属在表层土壤中的累积特征,探讨发生累积的重金属的输入途径和来源.结果表明：稻田土壤中Cu、Pb、Zn、Cd、Ni、As、Hg的含量分别为14.1～28.4、37.6～57.4、53.3～84.4、0.044～0.367、18.4～37.0、3.25～12.11、0.031～0.155 mg·kg^-1.Pb、Hg、Cd表现出明显的累积趋势,其含量超过基线值的比例分别为100.0%、38.7%和66.1%,其余重金属元素未出现累积现象.随着灌溉历史的增长,稻田土壤中Pb含量呈逐渐降低趋势,Hg含量呈逐渐升高趋势.Cd含量与灌溉历史的关系不明显.稻田土壤中累积的Pb主要与过去使用含Pb汽油产生的废气沉降有关;Hg主要来源于曾受污染的二松江水,随引水灌溉输入;Cd主要来源于化肥、农药等农用化学品的施用.尽管本区稻田土壤中Pb、Hg、Cd出现明显累积现象,但其生态风险水平很低,不会对当地农业生产及粮食安全构成威胁.     

三峡库区黑沟流域AnnAGNPS参数空间聚合效应

农业非点源污染物是长江三峡库区主要污染源之一,已造成令人关注的生态、环境和健康等问题,流域模型(AnnAGNPS)与GIS结合,为空间数据组织和模型参数空间聚合提供技术基础,是其预测和流域规划与管理的有效途径.三峡库区小流域条件下,基于临界源面积(CSA)和最小初始沟道长度(MSCL)值域设定,形成不同流域划分方案,空间离散单元(SDU)水平,即SDU大小及数量,影响输入参数空间聚合效应及模型输出结果.在黑沟小流域(144.4 hm~2)应用已校准AnnAGNPS模型,设定CSA和 MSCL值域为0.5～15hm~2及7.5～200m,10种SDU水平、流域尺度和条件下,结果表明:空间参数聚合程度和模型输出结果均随SDU尺度改变而发生变化.土地利用与土壤类型等参数具有明显的聚合效应,径流、泥沙和养分输出具有不同的SDU适宜水平和范围.SDU尺度聚合效应对径流量影响较小,而对泥沙、总N、总P模拟影响较大;径流量、泥沙、总N、总P模拟输出误差可接受SDU尺度范围分别为0.5～18、2～6、0.5～6 hm~2.因此,应用AnnAGNPS模型,更需要注意不同子模型所需要适宜的SDU尺度水平.     

贵州仙家洞和忆苦洞洞穴动物群落多样性及其环境因子的影响

为了解矿区洞穴动物群落多样性特征及其影响因素,于2019年3月对贵州松桃锰矿区仙家洞和忆苦洞的动物进行了调查,运用主成分(PCA)综合分析了环境因子对洞穴动物群落多样性的影响,并利用潜在生态危害指数对洞穴内土壤重金属的生态风险水平进行了评价.结果 表明:共获动物标本445号,隶属4门8纲18目32科,其中仙家洞178号...     

Distribution of medium- to large-sized African mammals based on habitat suitability models

The knowledge of the areas inhabited by a species within its distribution range and the connections among patches are critical pieces of information for successful conservation actions. The internal structure of the extent of occurrence (EO) of a species is almost always unknown, even for “well-known” flagship species. We developed a methodology to infer the area of occupancy (AO) within the EO of a species using the limited available data. We present here the results of a three years project funded by European Union to develop high-resolution models of habitat suitability for 281 medium- to large-sized African mammals across the whole continent. The existing literature was reviewed and all data on the geographic distribution and environmental preferences of the selected species were collected. For each species, these data were then expressed in terms of key variables available as GIS layers at a resolution of 1 km² over the entire African continent. The AO of each species was obtained merging the information on the ecological needs of the species and the values of ecological variables over the region identified as EO. The habitat suitability models were evaluated through direct field work in four countries (Morocco, Cameroon, Uganda, Botswana) chosen as representatives of the environmental and species diversity of Africa. More than 81% of models had positive true skill statistics (TSS) values, indicating models performing better than random. Rigorous modeling procedures supported by ad-hoc field evaluation allowed the production of high-resolution habitat suitability models useful for conservation applications.     

Energy gradients and the geographic distribution of local ant diversity

Geographical diversity gradients, even among local communities, can ultimately arise from geographical differences in speciation and extinction rates. We evaluated three models—energy-speciation, energy-abundance, and area—that predict how geographic trends in net diversification rates generate trends in diversity. We sampled 96 litter ant communities from four provinces: Australia, Madagascar, North America, and South America. The energy-speciation hypothesis best predicted ant species richness by accurately predicting the slope of the temperature diversity curve, and accounting for most of the variation in diversity. The communities showed a strong latitudinal gradient in species richness as well as inter-province differences in diversity. The former vanished in the temperature-diversity residuals, suggesting that the latitudinal gradient arises primarily from higher diversification rates in the tropics. However, inter-province differences in diversity persisted in those residuals—South American communities remained more diverse than those in North America and Australia even after the effects of temperature were removed.     

绿洲-荒漠交错带环境特征初步研究

以甘肃省石羊河下游的民勤绿洲为例,对其绿洲外围与荒漠交错地带的植被和植被关系密切的灌丛沙包特征进行了系统研究,结果表明,由于生态交错带边缘效应的存在,植被盖度的变化呈现绿洲附近与交错带外围靠近流沙的地方较低,而位于流沙和绿洲之间的部分相应较高,植被盖度较高的部位主要集中于自流动沙丘至绿洲外600m处,而非紧靠近绿洲、这与地下水自沙漠向绿洲方向运移有关,在绿洲外缘300～600m的范围内植被盖度出现下降,原因可能与绿洲荒漠交错带界外区的形成有关,说明研究区绿洲0～600m范围即是该区域绿洲界外区的存在区域,灌丛沙包上的裸沙率以绿洲界外区为最大,大量沙包裸露,可致沙子的活动性增强,因此该地带是对绿洲土地造成沙质荒漠化的最大流沙来源。     

Aspects of reproductive biology of curimba Prochilodus lacustris (Pisces,Prochilodontidae) in a tropical lake in Northeastern Brazil

This study evaluated the annual cycle of biological reproductive aspects of Prochilodus lacustris, a neotropical fish species, in Baixada Maranhense Protection Area in northeastern Brazil. Fish were collected monthly between June of 2015 and June of 2016 using gill nets. In the laboratory, 600 individuals were weighed, measured, and eviscerated to obtain biometric data and data for the microscopic and macroscopic analyses of the maturation stages of the gonads. These analyses allowed the determination of the reproductive period using biological indicators such as the gonadosomatic index and hepatosomatic index, condition factor, stomach repletion index, and spawning season. Abiotic variables were measured in situ during the samplig: temperature, pH, dissolved oxygen, and electrical conductivity. In addition, local rainfall data was also obtained. The results showed that the total body length of individuals varied from 151 to 211 mm in males, and from 142 to 239 mm in females. The sex ratio showed a predominance of females over males, and the species showed negative allometric growth. The annual variation of reproductive indicators and the frequency of individuals in advanced stages of gonadal maturation suggest that the reproductive cycle of the species occurs between November and January, with a reproductive peak in January. This reproductive peak coincides with the beginning of the region's rainy season. Although we did not do the fertility analysis, our results suggest that the species presents partitioned spawning. In conclusion, this results demonstrates that the reproduction of the investigated specie is influenced by associations between environmental variables on a seasonal scale and can be contribute to improve the understanding of the dynamics of the physiological reproductive process in lentic environments.