Variations in the morphological characteristics ofTriops granarius (Lucas) (Crustacea:Notostraca) in a pan system at Bain's Vlei,South Africa

The morphological characteristics of a population ofTriops granarius in a system of small pans were examined during inundations of one season. Considerable variation was found in a number of characteristics. Differences in gender other than those of the reproductive organs were also significant, but diagnostic characteristics remained stable.     

甘肃省民勤沙区土壤结皮理化性质研究

以甘肃民勤沙区为研究区域 ,分别采集了不同地貌部位和不同植被类型下的土壤结皮 ,并对其理化性质进行了初步分析。从结皮土壤的机械组成、土壤盐分、土壤养分、土壤阳离子交换量等方面来看 ,丘间地状况都明显要优于灌丛沙包。这可能与丘间地地形低洼 ,有利于土壤物质汇聚 ,以及其接受的大气降尘远较灌丛沙包为多有关。对于灌丛沙包来讲 ,白刺沙包在理化性质上 ,其状况要优于红柳结皮和梭梭结皮 ,这主要与其对环境的适应性及其所处的演替阶段有关。从目前的植被演替情况来看 ,白刺是当地的顶极种群 ,最适应环境 ,因此结皮发育状况也好 ;红柳目前已经处于极度退化进程中 ,而梭梭为人工植被 ,人工植被因在演替阶段中不起决定作用 ,故理化性质较差。另外从该研究工作还可以看出 ,对白刺植被采取围封措施之后 ,可以显著地促进结皮的生长发育 ,提高结皮中的有机质、全 N、全 P、速效 N等养分以及 Ca CO3含量。     

PGR-08理化性质及生物活性的研究

PGR-0 8是从某种土壤放线菌 (Actinomyces)的发酵液中分离提纯得到的白色结晶 ,纸层析和熔点检测证明它是化学单体 ,mp 1 80～ 1 81℃ ,[α]2 1D+ 4 3°(H2 O)。溶解性试验表明它易溶于 H2 O(≥ 6 0℃ )、HCl、Na OH、(CH3 ) 2 CO、CH3 OH和 C2 H5OH等 ,但不溶于 Na HCO3 。Tollen、Fehling和 Ag NO3 -溴酚兰等专性试剂的颜色反应表明其组成成分中有嘌呤和糖。生物试验证明 :PGR-0 8具有细胞分裂素的活性 ,例如它能减缓蒲公英离体叶圆片 Chl.的降解 ,延长叶圆片寿命 1～ 2倍以上 ,诱导叶圆片分化出不定根或不定芽 ,甚至建成小植株。它还能促进小麦种子萌发。     

Ecology of four turbid clay pans during a filling-drying cycle in the Paroo,semi-arid Australia

The clay pans studied were small (<2 ha), shallow (<30 cm) and contained very turbid, alkaline water of low conductivity for 40–90 days. Nutrients peaked early but chlorophyll-a values varied through time. Water temperatures ranged from 3.5 to 25.5 °C. Cumulative species richness ranged from 30 to 55, with mean momentary species richness varying from 15.5 to 29.1 among the four pans. Macroinvertebrate assemblages were dominated by adult phyllopods, hemipterans and coleopterans, and zooplankton was dominated by juvenile phyllopods, copepods and cladocerans. No macrophytes were present. Ordination showed two pairs of pans (A+B and C+D) which matched ordination of physicochemical data, with turbidity the factor best explaining the pattern. Macroinvertebrate assemblages varied between the centre and littoral zone of all pans, particularly in C and D in which CPOM was more abundant in the littoral. Grouping of assemblages was directed as much by differences in abundance as variation in species composition. Succession was directional and continuous. Among macroinvertebrates, insects dominated initially and terminally, but phyllopod crustaceans were important much of the time. In the zooplankton, phyllopods dominated initially then entomostracans, with final assemblages mostly consisting of copepods. Succession was quicker and later assemblages more stable in zooplankton. The feeding group of filter feeders/collectors dominated during the life of the pans, except at the beginning and end when predators were important. The major carbon source was algal, despite the high turbidity and abundant detrital matter.     

The large Branchiopoda (Crustacea) from temporary habitats of the Drakensberg region,South Africa

The Drakensberg forms part of the Escarpment which separates the coastal plain from the inland plateau in southern Africa. This mountain range runs for about 400 km along the KwaZulu-Natal/Lesotho border and into the Eastern Cape province of South Africa. Altitude ranges from 1500 to 3000 masl. Rock pools and tarns are the main type of temporary pool habitat in the Drakensberg. 90 different habitats were sampled over a four-year period and various physical and chemical characteristics of these pools are presented. Large branchiopods occurred in 26 of these habitats. Five Branchipodopsis and two Streptocephalus species composed the anostracan fauna, while Triops granarius was collected only from the summit of the Escarpment at one locality. Four genera of Spinicaudata are represented in the Drakensberg but the current state of the taxonomy of this group does not allow identification to species level. Absence of large branchiopods from a high percentage of temporary habitats could be attributed to predation or many pools may not be sufficiently ephemeral. Most pools were inhabited by a single species of large branchiopod. This could be a result of low levels of food resources in pools, as indicated by extremely low conductivities. Restricted food resources could also be the limiting factor in the distribution of Streptocephalus and Triops which are only found in pools with higher conductivities. Four of the five Branchipodopsis species are endemic to the Drakensberg pools. These habitats are also inhabited by a high diversity of ostracods and other micro-crustaceans. Most of the KwaZulu-Natal Drakensberg falls within conservation areas but the Lesotho and Free State localities could be threatened by future development.     

不同坡向高寒草甸土壤理化特性和微生物数量特征

阐明不同坡向草地土壤性质的空间分异格局,为退化草地的精准修复和科学管理提供参考。研究了青藏高原东缘高寒草甸退化草地不同坡向(北坡N、西北坡NW、西坡W、东坡E、东北坡NE、西南坡SW和南坡S)土壤理化性质和微生物数量特征。结果发现:从N→S坡向上,土壤有机质、碳氮比和全氮含量均呈下降趋势,土壤全磷含量和pH值在不同坡向间均无显著差异(P0.05),E坡向全磷含量最高((2.83±0.95)g/kg),NW坡向含量最低((2.07±0.12)g/kg);土壤细菌、真菌和放线菌数量变化呈波动现象,NW坡向的细菌((13.0×10~5±1.0×10~5)个/g)、真菌((14.0×10~3±0.0)个/g)和放线菌((24.0×10~4±1.0×10~4)个/g)数量最低,E坡向的细菌数量最高((85.5×10~5±2.5×10~5)个/g),S坡向的真菌((24.0×10~3±0.0)个/g)和放线菌((209.5×10~4±4.5×10~4)个/g)数量最高;回归分析表明,在E→S坡向上,随土壤含水量、有机质、碳氮比和全氮含量的增加,土壤细菌和放线菌数量均显著降低(P0.05),而土壤真菌数量随含水量、pH值、土壤养分含量的增加略有降低(P0.05)。可见,不同坡向高寒草甸土壤理化特征差异明显,也导致了土壤微生物数量分配格局的不同。     

Seasonal changes in the invertebrate community of small shallow ephemeral pans at Bain's Vlei, South Africa

Changes in invertebrate population numbers and composition were monitored in six small shallow ephemeral pans during four consecutive inundations of spring, summer and autumn 1988/1989. The community was generally characterized by crustaceans and was invaded by insect larvae in summer. Community changes and succession were prominent in spring but less so in summer and autumn. Large pans supported more species than small pans. During longer inundation there was less difference between the initial and the final population composition than during shorter inundation, although the total population density did not increase significantly. This indicated that population composition stabilized as inundation lengthened. Population changes of six representative taxa were not correlated to changes in the physical and chemical characteristics of the water.     

福建茶树害螨发生动态及其与茶树品种理化特性的相关性分析

用5点采叶取样法调查了茶树害螨发生特点。结果表明:各茶树品种的害螨盛发高峰期一般都出现在8月底到9月初;对2005年5品种茶树上害螨螨情指数高峰期进行方差分析,结果表明均达到极显著差异(F=4.141,P=0.0054)。对不同茶树品种的叶片理化指标与螨情指数进行相关分析,结果表明:叶片厚度与相应品种的螨情指数之间呈一定的负相关关系(F=0.3903,r=-0.4040);不同茶树品种的叶片下表皮及其角质层厚度和相应品种的螨情指数之间呈一定的正相关关系(F=2.40,r=0.7389);不同茶树品种叶片的咖啡因和GC含量与害螨螨情指数呈负相关,相关关系接近显著水平(F=3.44,r=-0.7309和F=5.96,r=-0.8156)。     

The macro-invertebrate communities of temporary pools in an intermittent stream in tropical Queensland

Nine pools were studied in an intermittent stream. They were close to each other but differed in size, substratum, amount of shade and duration of water presence. Initial conditions were set by wet season flooding, following which each pool developed its own character. Cluster analysis showed that communities changed substantially with time in both species composition and abundance, and that some initially similar communities diverged while some initially dissimilar ones converged.Principal Components Analysis showed that these community changes were due largely to the drying of the pools, and to seasonal effects. Specialised drying communities developed in the pools of longer duration (up to 8 months), but not in the short-lived pools (3–4 months). Apparently similar numerical responses in different pools were often caused by different suites of predominant species.The diversity of the fauna (total of 78 species) was high in comparison with similar habitats in non-tropical regions.The pattern of development of the pools' communities was much as expected from island biogeography theory, except that there was no relationship between species richness and duration and size of pools. The species complements were largely opportunistic, being governed by extreme environmental disturbance.     

三江平原草甸白浆土种稻后土壤理化性质变化

土壤质量变化与更新是农业发展和土壤管理的判断准则.白浆土是三江平原主要水田土壤,但旱田改水田后缺乏对其土壤质量变化规律的研究.本研究以不同种稻年限白浆土为调查对象,探讨其土壤理化性质演变特征.结果表明: 白浆土种稻后,耕层(厚16~23 cm)和犁底层(厚6~8 cm)土壤有机碳、还原物质总量增加,耕层深度随种稻年限增加呈逐渐增加趋势,犁底层无明显变化,心土层(厚20 cm)与旱田无显著差异;土壤中Fe²⁺和Mn²⁺有向下迁移现象,但只迁移到犁底层;耕层和犁底层土壤固相比率比种稻前增加,犁底层固相比率由47.8%增加到70.0%,容重由1.22 g·cm^-3增加到1.77 g·cm^-3,土壤孔隙总量降低,微孔隙比例增加,白浆土种稻后有黏粒淋溶淀积现象.白浆土种稻后,土壤物理和化学性质的变化特征与水稻土的演变规律既有一致性,又有其特殊性.     

The description and preliminary prediction of the inundation pattern in a temporary habitat of Anostraca,Notostraca and Conchostraca in South Africa

To explain the life-history strategies of temporary-water fauna, one must be able to describe the temporary habitat. It is necessary to know when it will be wet, how often this occurs, for what period each inundation lasts and what variability there is in this pattern. For logistics reasons one cannot follow each inundation in a pan for the ten years or more needed to establish a pattern. Based on the available inundation data for two seasons at Bain's Vlei Pan in a semi-arid part of South Africa, a model has been developed, using the rainfall pattern over ten years at nearby Bloemfontein, to predict inundation. Over a ten-year period preducted inundations ranged up to 87 days as a result of repeat-rain, with a mean period of 18.8 days, while a rain-episode of less than 20 mm was insufficient to inundate the pans. There was an average of 5.8 inundations per season. Single inundations do not exceed 20 days due to evaporation. When successive showers fall before periods of inundation are over, a specific extension of inundation is predictable. The precise implications of the inundation pattern on organisms requires much analysis. However, there are strong indications based on the growth, survival and pattern of egg-production among three species (Anostraca —Banchipodopsis tridens, Conchostracan —Leptestherialla inermis, and Notostracan —Triops granarius) from the pan and one species (Anostracan -Streptocephalus macrourus) from more permanent waters nearby, that the pattern of inundation is selective of the community held by the pan.     

南亚热带不同植被恢复模式下土壤理化性质

分析了广西大青山南亚热带11种植被恢复模式下（1种天然次生林、2种人工针叶林、5种人工常绿阔叶林、2种人工针阔混交林和1种灌丛）土壤理化性质的变化特征.结果表明:不同植被恢复模式下土壤理化性质存在明显差异.其中,次生林林地土壤的物理性质良好,2种针叶林较差.2种针阔混交林土壤容重较小,土壤总孔隙度、土壤持水量均高于其他人工纯林;而5种人工常绿阔叶林的土壤孔隙度差异不明显.次生林土壤除全K低于柚木林外,其余养分含量均明显高于人工林,C/N和pH值相对较低.与荒草灌丛相比,9种人工林的土壤养分变化明显,全N和速效P含量均呈增加趋势;2种针叶纯林的土壤养分含量较低,但与红椎混交后,土壤养分含量明显改善,C/N值降低.     

苔藓植物的化学元素含量及其特点

苔藓植物是化学元素最有效的积累者,在指示环境质量变化方面有其独到之处。本文阐述了苔藓植物体内地球化学元素的组成、含量、来源及其特点,用以揭示影响苔藓植物地球化学元素的因素,从而为苔藓植物作为指示生物提供更可靠的理论依据。苔藓植物体内所含的元素种类很多,主要来自大气沉降(如降水、降尘、扬尘、树冠淋溶等)和生长基质(如土壤、岩石等),元素含量受到区域空间、生态系统、苔藓种类以及时间季节的影响。苔藓植物体内地球化学元素含量可以指示环境条件(如区域空间、生态系统和时间)的差异。     

湿度对堆肥理化性质的影响

水分是堆肥微生物生命活动的基础 ,也是堆肥中重要的工艺控制参数。弄清湿度对堆肥微生物及理化性质的影响 ,对于优化堆肥工艺参数、提高堆肥效率、降低投资和运行成本具有重要意义。综述了堆肥湿度研究的动态 ,指出了当前研究中存在的问题 ,并提出了未来的研究方向。大量的研究表明 ,湿度低于 4 5 %或高于 6 5 %都不利于堆肥处理。湿度太高会导致堆料的压实度增加、FAS减少、透气性能降低 ,从而导致堆体内氧气供应不足、堆肥升温困难、有机物降解速率降低、堆肥周期延长。湿度过低 ,水分会限制堆肥微生物的新陈代谢 ,导致微生物活性下降、堆肥腐熟困难。由于鼓风、散热、水蒸发等会使堆体内存在湿度的空间变异 ,也会降低堆肥效率和堆肥产品的质量。另外 ,堆肥湿度还影响堆肥的保肥能力。由各文献得出结论 ,堆肥的最佳湿度范围一般为 5 0 %～ 6 0 %左右     

荒漠草原区4种植物群落土壤种子库特征及其土壤理化性质

土壤种子库作为地上植被更新的潜在种源,在植被自然恢复和演替过程以及生态系统建设中起着重要作用。以宁夏盐池县荒漠草原区4种植物群落为研究对象,通过对封育16年后植物群落土壤理化性质的变化与其土壤种子库的特征之间的关系的探讨,揭示荒漠草原植物群落的土壤种子库分布特征和演替趋势,以及土壤质量的改变如何影响土壤种子库特征。研究结果表明：（1）不同植物群落土壤种子库物种组成及种子密度不同,同一物种在不同植物群落土壤种子库中出现时种子密度也存在差异;禾本科、菊科、藜科植物种在4种植物群落土壤种子库中出现比例均较高,分别占到26.19%、21.43%和19.05%,占总物种数的66.7%;灰绿藜、冰草、碱蓬在4种植物群落土壤种子库中均有出现。（2）4种植物群落土壤种子库中多年生植物和一年生植物种子居多,灌木、半灌木植物种较少。（3）4种植物群落土壤种子库中物种数和种子密度均表现为：芨芨草群落 > 苦豆子群落 > 油蒿群落 > 盐爪爪群落;且随着土层的加深,4种植物群落土壤种子库中物种数和种子密度均呈递减趋势。（4）4种植物群落土壤种子库中Shannon-Wiener指数、Simpsin指数、Pielou指数和Patrick指数均表现为芨芨草群落 > 苦豆子群落 > 油蒿群落 > 盐爪爪群落。此外,芨芨草群落土壤种子库与油蒿群落土壤种子库相似性最高,油蒿群落与盐爪爪群落的最低。（5）土壤种子库物种多样性特征指数与土壤pH、含水量、碱解氮呈正相关,与土壤电导率呈负相关,其中土壤pH和电导率对种子库物种多样性的影响较大。荒漠草原封育以后,土壤种子库中植物种数、种子密度和物种多样性均呈增加趋势,且以多年生植物和一年生植物种子居多;禾本科和豆科植物的物种数和种子密度大于菊科和藜科,这表明围封后牧草品质改善,植物群落正向演替。     

Lateral hydrological connectivity differentially affects the community characteristics of multiple groups of aquatic invertebrates in tropical wetland pans in South Africa

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