EFFECTS OF SIMULATED CANOPY COVER AND ANIMAL DISTURBANCES ON RILL AND INTERRILL EROSION1

ABSTRACT: A rainfall simulator was used on runoff plots to study the effects of simulated canopy cover, trampling disturbance, and soil type on nil and interrill erosion. Sandy loam soil was more erodible than clay loam soil. Furthermore, the simulated canopy cover signffi-Soilfactorsrelatedtonil cantly influenced nil and interrill erosion. The effect of trampling on rill and interrill erosion varied with soil type (clay loam versus sandy loam) and erosion type (nh versus interrill erosion). On large plots, where both nil and internill erosion were involved, 30 percent trampling significantly increased soil loss. However, on small plots, 30 percent trampling significantly reduced interrill erosion.     

铜绿山矿冶废弃地优势植物重金属的积累与迁移

通过野外调查和取样分析,研究了大冶铜绿山矿冶废弃地鸭跖草等5种优势植物对重金属的吸收累积与迁移特性,以期为矿区退化生态系统的植被恢复、重金属污染土壤的治理等提供依据。结果表明,鸭跖草等5种植物对重金属Cu、Pb、Zn、Cd、Cr都有程度不等的高量积累,尤其是铜元素,其最高积累量出现在海洲香薷根部,达到844.65 mg/kg,是一般植物Cu含量（5~25 mg/kg）的33.8~1689倍;而在同样条件下,As在5种植物体内的含量为018~098 mg/kg,远远低于As在一般植物中的含量（＜10 mg/kg）,这说明这些植物对As可能具有某种规避机制。从植物对重金属的吸收、富集和转运能力综合考虑,鸭跖草等5种植物都不太可能是重金属Cu等6种重金属的超累积植物。但是,它们对重金属所表现出的耐性无疑对矿冶废弃地的植被恢复过程有重要意义。     

Spatial organization and behaviour of badgers <Emphasis Type="Italic">(Meles meles)</Emphasis> in a moderate-density population

Badgers are carnivores that show considerable variation in their social and spatial organization. At the westernmost part of their range, in Britain and Ireland, variation in spatial organization appears to be determined by the availability of resources. However, the majority of studies has focussed at one end of the social/spatial spectrum, where population densities are high and adjacent territories are contiguous and non-overlapping. To examine whether the same limiting factors appear to apply across a wider range of badger densities, we established a study site in a predominantly coniferous habitat within an upland area of northeast England, where population densities were predicted to be low. Seasonal home ranges of individual badgers were largest in autumn, followed by summer and spring, then winter. This pattern is reflective of the likely seasonal changes in food availability within the area, as opposed to being related to breeding patterns. There were also significant correlations between territory size and the number of grassland patches (positive) and the proportion of grassland (negative), which are consistent with predictions from the Resource Dispersion Hypothesis. Although badgers at the site were living at low to moderate densities relative to many other studied populations in Britain, they showed patterns of spatial organization that were close to those of high-density populations. The nature of the relationship between resource availability and abundance patterns is likely to have important consequences for the conservation and management of badgers and other species that show flexible spatial organization.     

Alkaloid tolerance in Manduca sexta and phylogenetically related sphingids (Lepidoptera: Sphingidae)

Summary. Nicotine tolerance is well known for Manduca sexta. It also occurs in several other sphingids of the subfamilies Macroglossinae and Sphinginae. Only members of the subfamily Smerinthinae appear to be more susceptible to nicotine intoxication. Phylogenetic trees have been reconstructed from mitochondrial 16S rDNA and nuclear DNA to map nicotine tolerance.?The nicotine binding site of both α-subunits of nicotinic acetylcholine receptors (nAChR) have been amplified and sequenced. No apparent amino acid substitution can be seen in the putative nicotine binding site of the α-subunits of nAChR from nicotine tolerant and nicotine sensitive sphingids. Thus, a simple target-site modification can be ruled out as a cause for nicotine tolerance. This finding agrees with feeding experiments: larvae of M. sexta and other sphingids of the Macroglossinae and Sphinginae not only tolerated nicotine, but also many other alkaloids that affect neuroreceptors other than acetylcholine receptors (nAChR, mAChR).?Only 10 to 20% of nicotine injected into larvae of nicotine-tolerant taxa could be recovered later as free nicotine, nicotine N-oxide or cotinine, i.e., 80 to 90% must have been converted to polar conjugates or degradation products which are not detectable with the methods applied. Usually more than 98% of the recoverable alkaloids were found in the faeces. Excretion reached a maximum 6 h after injection in tolerant taxa. Larvae of Manduca sexta, which were reared on a nicotine-rich diet, showed higher nicotine degradation and faster nicotine elimination than na?ve larvae. Application of the cytochrome P450 inhibitor SKF 525A (proadifen) reduced the formation of nicotine N-oxide and the rate of alkaloid degradation. Thus, an inducible detoxification mechanism, coupled with a rapid and inducible excretion, appear to be a strategy in Sphingidae that helps them to live on host plants rich in otherwise toxic secondary metabolites. Received 23 March 2001; accepted 4 August 2001.     

长程高脂肪膳食对大鼠空腹血糖及糖耐量的影响

研究了单纯高脂膳食喂养对大鼠空腹血糖(Fasting plasma glucose,FPG)及葡萄糖耐量(Glucose tolerancetest,GTT)的影响,旨在模拟与现代人生活饮食结构及发病情况更为接近的糖调节异常动物模型.取正常SD大鼠100只喂以普通饲料或高脂饲料14mo,动态监测动物体重及空腹血糖的变化,并分别在第5、8、10、14mo时用糖耐量试验观察葡萄糖耐量减退(IGT)的情况.结果显示,高脂喂养第1~14个月过程中,雄性大鼠的体重较普食组均未出现显著增加,而雌性大鼠体重仅在喂养第5~8个月期间较普食组增加了10%~15%;与普食组相比,在喂养高脂膳食第1~5个月中雌雄两性大鼠空腹血糖均显著升高,在喂养第5~10个月中雄性葡萄糖耐量显著减退,但雌性动物则未出现明显的IGT,至第14个月时雄性IGT与普食组的差异消失.研究表明,单纯高脂膳食虽不能诱发糖尿病,但可出现较典型的IFG空腹血糖受损和IGT现象,且以雄性动物造模更为适宜,喂养时间以10mo以内为宜.由于单纯高脂喂养更接近自然人群发病过程,因此,此种模型将为糖调节受损发生机制及其早期干预的研究提供新的动物模型.图2表1参12     

菌根真菌增加植物抗盐碱胁迫的机理

菌根是菌根真菌与高等植物根系形成的一种共生体，能够促进植物在瘠薄土壤中的生长。文章通过综合近20年来国内外在菌根植物抗盐碱研究方面的成就，论述了在高盐胁迫下，菌根对其寄主植物耐盐碱能力的影响；指出菌根植物可能主要通过以下4个方面增加对高浓度盐碱环境的抗性：增加植株对P等矿质营养元素的吸收，改善了盐胁迫引起的营养亏缺；改变植物体内离子平衡，降低其生理毒害；增加植株对水分的吸收和利用能力，缓解了生理性干旱；改变了植物根系形态，促进根系水分吸收能力。在分析菌根真菌增加植物抗盐碱胁迫机理的基础上，还对该问题的研究前景提出了设想，为盐碱地改良提供参考依据。     

高山植物唐古特红景天粘液细胞及叶肉细胞表面糖蛋白与抗冻性的关系

分布于青海高原海拔4000m高山的唐古特红景天有很强的抗冻能力，其叶片半致死温度可达－26.5℃。在北京地区夏季（7月）驯化20d后，长出新叶片的半致死温度升高为－15.5℃。光镜组织化学切片显示，在唐古特红景天叶片中，特别是维管组织周围，存在多糖、蛋白质或糖蛋白含量丰富的粘粹细胞；高温驯化后长出的新叶片这种粘液细胞明显减小或消失。电镜细胞化学研究揭示，在细胞壁外层及细胞间隙中分布着明显的糖蛋白，在北京地区驯化20d的唐古特红景天叶片中这种糖蛋白明显减少。因此推测，粘液细胞和叶肉细胞表面的糖蛋白层，对唐古特红景天抗冻能力可能起着重要的作用，图版1图2参20。     

不同木豆品种耐铝性的基因型差异及其机理研究

以6个品种的木豆为材料，探讨了木豆品种间耐铝性的基因型差异及其机制。铝对根伸长的抑制大小及苏木精对根尖的染色模式的研究结果表明，不同品种木豆的耐铝性基因型差异明显。在铝胁迫条件下，去除根尖吸附的粘胶，耐铝的基因型MD2和敏感的基因型MD5根的伸长率均减少，而根尖被苏木精染色程度加深；去除粘胶对MD2的影响大于MD5，说明粘胶对根尖的保护是木豆抵御铝毒的一个重要机制。虽然铝胁迫可诱导木豆根系分泌柠檬酸和苹果酸，但根系苹果酸的分泌量在MD2和MD间无显著差异，MD2柠檬酸的分泌量甚至低于MD5。     

鞭式节丛孢(Arthrobotrys flagrans CBS583.91)对氯化钠和氯化镉的耐受性

首次报道了鞭式节丛孢的氯化钠和氯化镉耐受性,在查氏平板上培养39d，鞭式节丛孢对氯化钠的最高耐受浓度为0．6mol L^-1，对氯化镉的最高耐受浓度为3．0mmol L^-1；在LCMA平板上，0．18mol L^-1氯化钠抑制三维菌网的形成，0．30mol L^-1氯化钠抑制厚垣孢子的萌发，0．05mmol L^-1氯化镉抑制三维菌网形成，0．07mmol L^-1氯化镉抑制厚垣孢子萌发．图1表3参8     

Bisexually bonded ranging in chimpanzees (Pan troglodytes verus)

Abstact While male mammals seek to maximize access to potential mates, females maximize feeding efficiency. Ranging patterns are therefore often sex specific. Sex-specific ranging patterns have also been reported for East African chimpanzees and a recent study on female ranging patterns concludes that social organization is best described by a male-bonded community model, where females occupy individual home ranges that are distributed within the boundaries of the male-defended range. In West African chimpanzees, however, such sex-specific ranging patterns have not been consistently observed and a bisexually bonded community model, where both sexes use the entire home range equally, has been suggested to best describe social organization. In this study we analyze 5 years of data on individual ranging patterns of chimpanzees in the Taï National Park (Côte dIvoire) to test specific predictions of the different models of chimpanzee social organization. We found that although males in Taï had slightly larger home ranges than females, all individual home ranges and core areas overlapped highly. Small individual home range size differences were entirely due to the use of peripheral areas and were correlated with female social dominance. These findings strongly support the bisexually bonded community model for Taï chimpanzees. Thus, we conclude that there are fundamental differences in the space-use patterns of East and West African chimpanzees and discuss possible factors leading to such differences.Communicated by D. Watts