不同山系大熊猫栖息地植物区系特征的定量分析

本文通过对不同山系大熊猫栖息地(自然保护区)植物区系的定量分析发现,野生大熊猫栖息地的植物区系主要以温带分布类型为主,占总区系的31.10%;区系多样性指数中Shannon-Wiener指数为2.10~2.21,Simpson指数是0.14~0.17;经相关性分析,不同山系大熊猫栖息地之间相似程度极为显著,相关系数达到0.905~0.998。     

Fruit infestation of Acacia tortilis (Forsk) hyne by Bruchidius andrewesi Pic. (Coleoptera: Bruchidae) in the Thar desert

Bruchidius andrewesi Pic. has been recorded as a serious pest of pods and seeds of Acacia tortilis in the Thar desert of India. Pest infestation on developing pods and its relationship with morphological traits is reported. Pod infestation varied from 5 to 19% with 5–29% infestation of seeds. Infestation of pods is directly related to infestation of seed (r = 0.72^**), and both pod and seed infestation are also directly correlated with loss in seed biomass (r = 0.79^** and R = 0.88^**). The infestation of pods starts in November and increases steady until harvest. Seeds kept in the laboratory for further studies were found to be 100% infested with B. andrewesi, as the insect multiplied faster under these conditions. The heavy infestation is damaging not only to A. tortilis but also to other leguminous trees of the desert. Bruchidius andrewesi has also been found on pods and seeds of Prosopis cineraria, an important indigenous tree of the region.     

梭梭被肉苁蓉寄生后的生理代谢反应

在新疆吉木萨尔县林木良种试验站肉苁蓉良种繁育基地内,选择立地条件、梭梭树龄、林分密度、林木株行距、接种肉苁蓉方式以及管理措施等基本一致的梭梭人工林为试验地,以被肉苁蓉寄生、未被肉苁蓉寄生和曾被肉苁蓉寄生但已解除寄生关系的梭梭为研究对象,通过对梭梭同化枝的相对含水量、束缚水/自由水、叶绿素、脯氨酸、丙二醛含量等水分代谢和生化指标的测定,研究梭梭被肉苁蓉寄生以后的生理代谢反应.结果表明:与未被肉苁蓉寄生的以及曾被肉苁蓉寄生但采收了肉苁蓉种子的梭梭比较,被肉苁蓉寄生的梭梭同化枝的相对含水量有所降低,而束缚水/自由水的比值有所提高;与此同时,被肉苁蓉寄生的梭梭同化枝的叶绿素含量降低,而脯氨酸和丙二醛含量有所提高.三者之间的各项测定指标的差异达到显著程度.梭梭被肉苁蓉寄生以后引发的一系列生理代谢反应,既是梭梭被肉苁蓉寄生以后的一种生理代谢适应,也是引起被肉苁蓉寄生的梭梭生长衰退的主要原因之一.     

森林病虫害发生与生态环境变化

文章论述了我国森林病虫害发生的情况及分析了发生的原因,并对森林病虫害的发生与生态环境变化之间的相互关系进行了分析,提出森林病虫害的发生与生态环境这两者之间是相辅相成、互相影响的。     

灰色系统理论在柽柳属植物扦插繁殖筛选中的应用

采用灰色系统关联度分析方法,分析并计算了8个柽柳属植物种之间的关联度以及它们扦插繁殖中的7个观测指标值间的关联度大小,结果表明:柽柳枝条扦插繁殖观测指标间的关联度大小顺序是茎粗>地上生物量>主根长>株高>侧根数>一级分枝数;柽柳种间的关联度大小顺序是中国柽柳>甘肃柽柳>甘蒙柽柳>刚毛柽柳>短穗柽柳>长穗柽柳>紫杆柽柳>多枝柽柳,关联度的大小可以反映出柽柳种间及扦插繁殖观测指标间的主次顺序。     

土壤盐胁迫下杨树次生木质部的解剖特征

对生长在苏北沿海防护林不同土壤盐度下的主栽树种杨树(欧美杨无性系69杨)进行了解剖,描述了杨树次生木质部结构的特征,测量了次生木质部的16个数量特征：年轮宽度(ARW)、导管长度(VL)、早材和晚材的导管分子面积(VA)、导管周长(VP)、导管直径(VD)、导管单孔率(PSV)、导管频率(VF)、纤维长度(FL)、纤维宽度(FW)、射线高度(RH)和射线频率(RF)。实验结果表明,在不同的土壤盐度胁迫下：(1)杨树次生木质部形态特征的差别不明显,但是组成分子趋向于小型化。(2)次生木质部数量特征的变化比较明显,即当土壤含盐量从0．036％逐渐升高到0．289％,杨树的年轮宽度变小,0．91→0．77mm;纤维长度和宽度的变化分别为693．8→570μm和14．9→13．5μm,射线高度和频率的变化分别为284．3→249．2μm和58．9→75．5mm^-2,表明在盐胁迫下杨树的生长受到抑制。随着盐度的增加0．036％→0．289％,杨树导管长度减小,367．6→341．5μm;在早材和晚材中,导管面积变化分别为1575．6→1703．6μm^2和760．1→947．7μm^2,导管周长变化分别为167．7→195．1μm和120．8→143．7μm,导管直径的变化分别为41．8→43．4μm和29．1→33．1μm,导管频率的变化分别为141．8→144．2mm^-2和160→206．7mm^-2;导管单孔率的变化分别为65．9％→30．5％和59．4％→40．8％。这些都表明在盐胁迫下杨树的导管缩短变粗,呈聚集分布,输水效率和输水安全性都有所提高。     

铬污染归宿的同位素原位监测法

铬(Cr)污染的迁移和环境毒性主要取决于其化学形态。在环境中,如果移动性及毒性较大的Cr(Ⅵ)能被还原为移动性及毒性较小的Cr(Ⅲ),并且还原速率大于污染速率,那么对铬污染的自然生态修复治理是可行的。铬在氧化还原过程中,存在着同位素动力学分馏效应,致使同位素比率发生移动,移动的大小和反应进程有关,服从Reyleigh关系方程。因此,利用同位素测定可以确定Cr(Ⅵ)的归宿,用于铬(Cr)污染自然修复的监测。本文就环境铬污染自然生态修复中,应用同位素原位分析法进行监测的基本原理、分析过程及应用的可行性进行了阐述。     

青鱼消化器官数量性状胚后发育规律

采用显微解剖和测量、光镜和扫描电镜观察方法，系统观测全长为５．６～３３０．０ｍｍ的青鱼标本３７０尾，描述了鳃耙、咽齿、角质垫和肠等消化器官数量性状在胚后发育过程中的变化规律；论述了青鱼的摄食特性、消化器官数量性状胚后发育的阶段性及其相关性、消化器官数量性状发育与食性转化，为制订培育青鱼苗种和饲养成鱼的生物学技术提供了可靠依据     

渔业资源管理目标定量确定的探讨

本文主要探讨渔业资源管理目标定量确定(包括渔业种类及其可捕规格和产量的确定)过程中常用的数学方法，并指出各种方法的应用范围。     

New method using quantitative PCR to follow the tick blood meal and to assess the anti-feeding effect of topical acaricide against Rhipicephalus sanguineus on dogs

A 28-day study was conducted to assess the dynamic of blood feeding by Rhipicephalus sanguineus ticks on dogs treated or not with a novel topical combination of fipronil, amitraz and (S)-methoprene. Dogs were infested weekly through exposure to ticks in crates for 4 h. Ticks were then counted in the crates at 2 h and 4 h post dog exposure. Ticks were also counted and removed from the dogs at 2 h, 4 h, 6 h, 12 h and 24 h post tick exposure. The inhibition of blood feeding was assessed by both tick quantification and designing and performing a quantitative PCR (qPCR) to detect the canine hydroxymethylbilane synthase (HMBS) gene in ticks. The percentage of repellency sensu lato based on the ticks collected in crates at 2 h varied from 4.7% at day 28 to 48.3% at day 7. The immediate mortality rate of the ticks expelled at 2 h varied from 1.5% at day 21 to 31.7% at day 7. The efficacy calculation showed that the acaricidal combination started to kill ticks in as little as 2 h. The average efficacy reached 90.0% at 12 h post crate challenges and 100% at 24 h post exposure in crates. The inclusion of an internal amplification control was used to ensure that no significant template-derived PCR inhibition (≤6.2%) affected the overall results. The reduction of blood feeding was significant at 4 h (>80.0%) and >99.0% at 24 h post tick exposure in the crate. The high repellency rate and the lethal efficacy of CERTIFECT^® resulted in significantly fewer live attached ticks, consequently reducing blood intake and fluid exchanges.