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1.
I.CORRELATIONBETWEENL0ESSSECTI0NAND0XYGENIS0TOPESTAGESIntheYuanloessarea,manyscientiststhinkthatthesedimentsarecontinuousandtheclimaticrecordsareperfect.Thisdoesnotappeartobeaccurate.Sedimentationwasdiscontinuousinmanysections.Forexample,manyscientistsarguethatS2corresp0ndstooxygenisot0peStage7(Liu,l985,KuklaandAn,l989;Dingetal.,l990).lnfact,S2includesthreelayersfS2SSl,S2LLlandS2SS2.Dingetal.(l990)reportedthatthereisathickunitofloessbetweenS2SSlandS2SS2intheBaicao… 相似文献
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秸秆还田对耕作黑土中小型土壤动物群落的影响 总被引:2,自引:0,他引:2
为了考察秸秆还田对耕作黑土中土壤动物群落结构的影响,2009年到2011年在黑龙江省海伦市进行了定点实验,调查了样地A(17kg秸秆+含高浓度催腐剂还田)、样地B(8.5kg秸秆+含低浓度催腐剂还田)、样地C(对照样地),样地D(8.5kg秸秆还田),样地E(17kg秸秆还田)的中小型土壤动物群落结构。共获取中小型土壤动物21779只,分别隶属于58个类群。其中,甲螨亚目、姬跳虫科、棘跳虫科与驼跳科4个类群土壤动物在本地区是最适应环境变化的土壤动物类群。土壤动物群落结构分析表明,对照样地C中土壤动物密度最高(46591.67只/m~2),土壤动物类群最多(17.17),土壤动物优势度指数最大(0.37),样地D中土壤动物丰富度指数最多(2.63),样地A中土壤动物多样性指数最高(1.72),样地B中土壤动物均匀性最高(0.64)。同时,各样地土壤动物基本都具有表聚性,样地A中土壤动物更趋于生存于上层土壤。综合比较分析表明,样地A秸秆还田方式相对来说最利于土壤动物生存。主成分分析表明,不同秸秆还田方式对土壤动物密度、甲螨亚目动物类群、节跳虫科类群、前气门亚目类群影响较大,是耕作黑土中对秸秆还田方式反应敏感的土壤动物指标,今后可以作为考察耕作黑土秸秆还田肥力效应的评价指标。另外,CAA分析表明:受土壤环境因子影响较大的土壤动物类群多为研究区域内优势类群与常见类群,土壤动物的密度与土壤中有机质、有机碳、碳氮比与全磷的含量关系最为密切。 相似文献
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玉米-大豆间作和施氮对红壤地中小型土壤动物群落特征的影响 总被引:1,自引:0,他引:1
通过2年田间定位试验(2013—2014),利用干漏斗法收集土壤中小型动物,探讨不同种植模式(玉米单作、玉米大豆间作、大豆单作)和施氮(0、150 kg·hm-2)对红壤土壤动物数量和群落结构的影响.结果表明: 两年取样共捕获土壤中小型动物8349只,分属3门10纲29目,优势类群为蜱螨目和弹尾目.2013年间作和施氮均提高了玉米拔节期土壤动物的平均密度.2014年土壤动物类群数较2013年有明显的增加,施氮条件下的土壤动物平均密度较不施氮有所增加.两年多因素方差分析结果表明,种植模式和生育期对土壤动物平均密度、类群数和多样性指数都无显著影响.但在2014年,施氮显著影响了土壤动物类群数、Simpson指数和密度-类群指数;种植模式与玉米生育期的交互作用显著影响了土壤动物平均密度和类群数,同时对密度-类群和丰富度指数也有显著影响;施氮和生育期的交互作用显著影响了Simpson指数、密度-类群指数和Shannon指数.从两年的土壤动物群落去趋势分析结果来看,红壤地土壤动物群落在种植模式和施氮水平之间均没有明显的差异,群落组成的变化与玉米生育期相关.合理施氮条件下的玉米-大豆间作模式有利于提高红壤地土壤中小型动物平均密度和类群数,保持较好的多样性. 相似文献
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《水生昆虫》2012,34(2):139-155
In the Volga Basin, the small Baikalian amphipod Gmelinoides fasciatus was introduced in 1965 into the Gorky reservoir in order to enhance fish production; it appeared in 1986 in the Rybinsk reservoir and we recorded it during monitoring activities in 2006 at Tver. In total, at the monitoring site Tver/Migalovo 69 benthic invertebrate taxa were identified. We compared data from three summer seasons. During summer low flow period Gmelinoides fasciatus did not exceed a share of 12.6% considering individual (ind) densities (mean abundance 165 ± 104 ind m?2) and 14.2% considering biomass (mean biomass 0.39 ± 0.44 g m?2). Abundances and biomass of G. fasciatus were shown to be stable over three years and no increase was observed. The monthly dataset (March–November 2008) revealed dynamics in relation to the native benthic communities and it was shown that the maximal densities of Gmelinoides did not exceed 587 ind m–2. Understanding the effects on benthic communities caused by the invasive amphipod Gmelinoides fasciatus is crucial in order to predict further developments in European inland waters and to establish management strategies. 相似文献
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M. DORA FELICIANGELI JAIME RAMIREZ PEREZ ALIRIO RAMIREZ 《Medical and veterinary entomology》1988,2(1):47-65
Phlebotomine sandflies were surveyed in two ecologically contrasted areas, the northern moist and southern wet tropical forests, of the Territorio Federal Amazonas, Venezuela. Three new taxa and twenty-one new records were added to the previously known species list for Venezuelan sandflies, which now totals eighty species. Both sexes of Lutzomyia (Psychodopygus) killicki sp.n., L. (Trichophoryomyia) bettinii sp.n., L. (Nyssomyia) olmeca reducta subsp.n. and and the females of L. bernalei Osorno et al., Brumptomyia pintoi Costa Lima and L. begonae (Ortiz & Torres) are described and illustrated. 相似文献
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B. D. Hansen J. French K. A. Handasyde T. A. Kendal A. C. Taylor 《Molecular ecology resources》2003,3(2):212-214
The New Guinean endemic dactylopsilines are members of the Petauridae possum family, represented in Australia only by the striped possum Dactylopsila trivirgata. The shy nature and low density of this species have hampered studies of its ecology to date, so we developed nine highly variable polymorphic microsatellite markers to enable molecular genetic analysis of population structure and mating system parameters. This will add substantially to our understanding of the behavioural ecology of this species. The low degree of cross‐amplification of the primers in other petaurid species lends weight to other evidence suggesting that this family underwent a relatively early radiation. 相似文献
10.
Evaluation of the water quality of future tributaries to the planned Dobczyce reservoir (Poland) using macroinvertebrates 总被引:1,自引:1,他引:0
Tadeusz M. Fleituch 《Hydrobiologia》1992,237(2):103-116
The bottom fauna of 5 tributaries of the planned Dobczyce reservoir and the River Raba below the dam was investigated in the preimpoundment period (1983–84). The abundance of macrofauna varied between 46 taxa (Wolnica stream) and 66 taxa (Brzezówka stream). Each station showed individual taxa composition except for the RABA-u and RABA-d (84% similarity). On the basis of 7 different biological indices the stations were divided into 3 categories: unpolluted (Brzezówka), slightly polluted (Bulinka, Trzemésnia and both Raba stations), and moderately polluted (Wolnica). Most sensitive to chemical pollution was the BIOTIC-index. The combination of environmental variables was used to predict biological indices. The most significant relationship (P < 0.01, R
2 = 0.71) was found between the BIOTIC-index and physico-chemical factors. Some problems in the application of indices (sampling, indicator organisms and interpretation of the results) are discussed and local adaptations of methods used are recommended. 相似文献