区域生态风险评价——以呼和浩特市区为例

区域生态风险具有大尺度、多因素、多风险受体的特点,难以直接定量;从生态风险的定义出发,构建景观破碎度和面积加权生态价值指数评价区域生态风险,并以ArcGIS和Fragstats软件为研究平台,通过空间采样和插值方法得到区域生态风险的空间分布规律。以2006年Spot卫星遥感数据解译的呼和浩特市区土地利用图为例,研究结果表明生态风险值范围在0.04-0.26之间,空间梯度差异明显,风险较高区域为东北部的大青山山区以及西南角的平原农业区,北部风险驱动力主要来自土壤侵蚀、地下水源地水位下降、水质恶化以及林地的退化;南部则是快速工业化导致林地、草地、特别是耕地景观转换为居民与工矿用地景观。案例研究结果表明所建方法直观、简便,可定量描述区域景观生态风险的相对大小和空间分布规律。     

Mapping QTLs for seed yield and drought susceptibility index in soy-bean（Glycine max L.） across different environments

Drought stress has long been a major constraint in maintaining yield stability of soybean （Glycine max （L.） Merr.） in rainfed ecosystems. The identification of consistent quantitative trait loci （QTL） involving seed yield per plant （YP） and drought susceptibility index （DSI） in a population across different environments would therefore be important in molecular marker-assisted breeding of soybean cultivars suitable for rainfed regions. The YP of a recombinant line population of 184 F2：7：11 lines from a cross of Kefengl and Nannong1138-2 was studied under water-stressed （WS） and well-watered （WW） conditions in field （F） and greenhouse （G） trials, and DSI for yield was calculated in two trials. Nineteen QTLs associated with YP-WS and YP-WW, and 10 QTLs associated with DSI, were identi- fied. Comparison of these QTL locations with previous findings showed that the majority of these regions control one or more traits re- lated to yield and other agronomic traits. One QTL on molecular linkage group （MLG） K for YP-F, and two QTLs on MLG C2 for YP-G, remained constant across different water regimes. The regions on MLG C2 for YP-WW-F and MLG H for YP-WS-F had a pleiotropic effect on DSI-F, and MLG A1 for YP-WS-G had a pleiotropic effect on DSI-G. The identification of consistent QTLs for YP and DSI across different environments will significantly improve the efficiency of selecting for drought tolerance in soybean.     

新疆艾比湖湿地自然保护区植物的生态分组

应用列联表的χ~2检验和Spearman相关系数研究了艾比湖湿地自然保护区植物的种间联结性和相关性.依据测定结果,将艾比湖湿地自然保护区的植物划分为4个生态种组:梭梭+盐节木+白麻+盐爪爪+琵琶柴+碱蓬+花花柴+骆驼刺+绢蒿+白刺+芦苇、小獐茅+多枝柽柳+滨藜+小叶碱蓬+盐豆木+鹅绒藤+盐穗木、胡杨+白梭梭、奶浆草+甘草+西北天门冬+赖草+罗布麻.各生态种组内,物种间具备最大的种问联结性和相关性.长期的演替过程使各生态种组对生境有最大的适应能力,各自分别生活于过渡带的盐化平原低地、湖滨盐沼地、荒漠和荒漠优势种间的阳斑.今后在艾比湖湿地自然保护区植物的保护和恢复中,以整个生态种组的角度出发较单个植物的保护和恢复更为有效.     

Rapid evolution of outer egg membrane proteins in the Drosophila melanogaster subgroup: a case of ecologically driven evolution of female reproductive traits

Although sexual selection has been predominantly used to explain the rapid evolution of sexual traits, eggs of oviparous organisms directly face both the challenges of sexual selection as well as natural selection (environmental challenges, survival in niches, etc.). Being the outermost membrane in most insect eggs, the chorion layer is the interface between the embryo and the environment, thereby serving to protect the egg. Adaptive ecological radiations such as divergence in ovipositional substrate usage and host-plant specializations can therefore influence the evolution of eggshell proteins. We can hypothesize that proteins localized on the outer eggshell may be affected to a greater degree by ecological challenges compared with inner eggshell proteins, and therefore, proteins localized in the outer eggshell (chorion membrane) may evolve differently (faster) than proteins localized in the inner egg membrane (vitelline membrane). We compared the evolutionary divergence of vitelline with chorion membrane proteins in species of the melanogaster subgroup and found that chorion proteins as a group are indeed evolving faster than vitelline membrane proteins. At least one vitelline membrane protein (Vm32E), specifically localized on the outer eggshell, is also evolving faster than other vitelline membrane proteins suggesting that all proteins localized on the outer eggshell may be evolving rapidly. We also found evidence that specific codons in chorion proteins cp15 and cp16 are evolving under positive selection. Polymorphism surveys of cp16 revealed inflated levels of divergence relative to polymorphism in specific regions of the gene, indicating that these regions are under strong selection. At the morphological level, we found notable difference in eggshell surface morphologies between specialist (Drosophila sechellia and Drosophila erecta) and generalist species of Drosophila. We do not know if any of the chorion proteins actually interact with spermatozoids, therefore leaving the possibility of rapid evolution through gametic interaction wide open. At this point, however, our results support previous suggestions that divergences in ecology, particularly, ovipositional substrate divergences may be a strong force driving the evolution of eggshell proteins.     

Dynamics of leaf area and nitrogen in the canopy of an annual herb, <Emphasis Type="Italic">Xanthium canadense</Emphasis>

We studied leaf area and nitrogen dynamics in the canopy of stands of an annual herb Xanthium canadense, grown at a high (HN)- and a low-nitorgen (LN) availability. Standing leaf area increased continuously through the vegetative growth period in the LN stand, or leveled off in the later stage in the HN stand. When scaled against standing leaf area, both production and loss rates of leaf area increased but with different patterns: the production rate was retarded, while the loss rate was accelerated, implying an upper limit of standing leaf area of the canopy. The rate of leaf-area production was higher in the HN than in the LN stand, which was caused by the higher rate of leaf production per standing leaf area as well as the greater standing leaf area in the HN stand. Although the rate of leaf-area loss was higher in the HN than in the LN stand, it was not significantly different between the two stands when compared at a common standing leaf area, suggesting involvement of light climate in determination of the leaf-loss rate. On the other hand, the rate of leaf-area loss was positively correlated with nitrogen demand for leaf area development across the two stands, suggesting that leaf loss was caused by retranslocation of nitrogen for construction of new leaves. A simple simulation model of leaf and nitrogen dynamics in the canopy showed that, at steady state, where the rate of leaf-area loss becomes equal to the production rate, the standing leaf area was still greater in the HN than in the LN stand. Similarly, when the uptake and loss of nitrogen are equilibrated, the standing nitrogen was greater in the HN than in the LN stand. These results suggest that leaf-area production is strongly controlled by nitrogen availability, while both nitrogen and light climate determine leaf-loss rates in the canopy.     

地表火干扰时间序列上樟子松林竞争强度的变化

林火是樟子松林重要的干扰因子,通过空间代替时间对地表火干扰时间序列上的天然樟子松林进行全林木定位调查,以单木竞争模型分析林分不同组分的竞争强度,通过Kriging法估计了火后林下更新幼树的密度。结果表明,存活林木各组分的竞争强度均显著地降低;地表火干扰12 a后存活林木各组分的竞争强度均比火后1 a存活林木相应各组分的竞争强度显著地降低;另外,火后更新幼树也更多地趋于地表火干扰形成的林隙中。因此,地表火干扰时间序列上林木竞争强度显著的持续降低,火后存活个体将有更充足的可利用资源和环境,林火成为樟子松林发育演替的重要驱动力。     

高温胁迫下五种杜鹃花属植物的生理变化及其耐热性比较

高温是制约分布于较高海拔地区杜鹃花迁地保育与园林应用的重要因子.为探讨杜鹃花属植物的 高温致伤机理,该实验以隶属不同亚属的白花杜鹃、羊踯躅、毛棉杜鹃、红滩杜鹃及红棕杜鹃4年生实生苗为 材料,通过人工气候箱的盆栽实验,研究了30℃、38℃高温胁迫下其叶片生理生化指标的变化,并利用隶属 函数法及系统聚类分析法对其种间...     

Cu污染土壤中溪荪和花菖蒲的生长状况及对Cu的积累及转运能力

采用土壤栽培方法,研究了在Cu添加量为0(CK)、200、400、600、800和1 000μg·g-1的土壤中溪荪(Iris sanguinea Donn es Horn.)和花菖蒲(I.ensata Thunb.var.hortensis Makino et Nemoto)叶和根的数量、长度及生物量(干质量)6个生长指标的变化趋势,并对叶和根中的Cu含量和积累量、全株的Cu积累量、Cu的富集系数及转运系数进行了比较分析.结果表明:随土壤中Cu添加量的提高,溪荪的根数逐渐降低且显著低于对照;而溪荪的其余5个生长指标和花菖蒲的6个生长指标均总体呈现出在Cu添加量较低的条件下逐渐增加并显著高于对照、在Cu添加量较高的条件下逐渐减小且显著小于对照的变化趋势;其中在Cu添加量1 000μg·g-1的土壤中2种植物的生长均受到显著抑制(P＜0.05);而添加400和600μg·g-1Cu则分别对2种植物的生长有一定的促进作用.随土壤中Cu添加量的增加,溪荪和花菖蒲叶及根中的Cu含量均逐渐提高;溪荪对Cu的富集系数和转运系数以及花菖蒲对Cu的富集系数均显著小于对照,而花菖蒲对Cu的转运系数则呈现在Cu添加量较低的条件下高于对照、Cu添加量较高的条件下低于对照并逐渐减小的趋势;在添加了Cu的土壤中,溪荪叶、根和全株对Cu的积累量均低于花菖蒲,但均显著高于对照,且2种植物根的Cu含量及积累量均大于叶片,表明溪荪和花菖蒲均具有一定的Cu积累能力,且主要积累在根中,花菖蒲对Cu的积累能力优于溪荪.综合分析结果显示:溪荪和花菖蒲不是Cu超积累植物,但对Cu胁迫均具有一定的耐性,且花菖蒲的耐性略强于溪荪;溪荪和花菖蒲分别适宜栽植于Cu含量400和600μg·g-1以下的土壤中,可用于轻度和中度Cu污染土壤的植物修复和环境美化.     

跟骨强度指数与影响因素相关性分析

目的：探讨跟骨强度指数与其影响因素的相关性。方法：共入选1024例体检人员。（1）通过Achilles定量超声（QUS）系统测量左跟骨强度指数;（2）使用RGC-120型体重秤测量身高、体重并计算体重指数;（3）通过问卷调查收集体检人员年龄、膳食、运动、吸烟、饮酒等影响因素的相关资料;（4）将各影响因素与跟骨强度指数进行相关分析和多元逐步回归分析。结果：（1）直线相关分析结果显示,跟骨强度指数与身高、体重、体重指数、饮用牛奶年数、运动年数呈正相关（;2）多因素逐步回归分析显示,跟骨强度指数仅与体重指数、运动年数具有显著的回归效果。结论：体重指数与运动年数是跟骨强度指数的独立影响因素,对骨质疏松的诊断与预防具有重要的意义。     

取食转Bt基因棉花上的棉蚜对丽草蛉发育和繁殖的影响

为明确转Bt基因抗虫棉对捕食性天敌的生态效应 ,比较了 2种转Bt基因抗虫棉 (GK-1 2和新棉99B)和 1种常规棉上的棉蚜Chrysopaformosa对丽草蛉Aphisgossypii发育和繁殖的影响。结果表明 ,(1 )与取食常规棉泗棉 3号上棉蚜的对照相比 ,取食转Bt基因抗虫棉GK- 1 2上棉蚜的第 1代和第 2代丽草蛉 ,其幼虫期和茧期的死亡率、幼虫和茧的发育历期、茧重及成虫性比等均与对照无显著差异 ;但第 1代成虫的产卵量减少了 2 88 0粒 ,与对照差异显著 (P <0 . 0 1 ) ;第 2代成虫所产卵的孵化率为 64. 0 % ,显著低于对照的 77. 7% (P <0 0 1 )。 (2 ) 2个品种的Bt棉对丽草蛉发育和繁殖的影响也略有差异。与取食GK 1 2上棉蚜的个体相比 ,取食新棉 99B上蚜虫的第 1代丽草蛉 ,其幼虫发育历期缩短了 0 . 6d(P <0 0 1 ) ,茧期缩短了 0 . 7d(P <0 . 0 1 ) ,茧重降低了 1 . 2mg(P <0 .0 1 ) ,幼虫期和茧期的死亡率、茧重以及成虫性比等则无显著差异 ;雌成虫产卵前期、产卵期、产卵量和寿命等繁殖学特性也无显著差异 ,但其成虫所产卵的孵化率为 65. 0 % ,显著低于取食GK- 1 2上棉蚜的处理 (72 . 7% ,P <0. 0 1 )。分别取食 2种Bt棉上的棉蚜 ,对第 2代丽草蛉的发育和繁殖的影响差异则较小。