中国美登木属的新分类群

本文拟定中国美登木属4新种1新等级,它们是:广南美登木M. guangnanensis H.Shao,蒙自美登木M. mengziensis H.Shao,易门美登木M. yimenensis H.Shao,树状美登木M. arboreus H.Shao和疏刺刺茶M. variabilis(Hemsl.)C.Y.Cheng var.inermis(C.Y.Cheng et W.L.Sha)H.Shao。     

云南寸金草新变型

本文发表寸金草一新变型,白花寸金草Clinopodium megalanthum f.leucanthum.     

云南贡山异叶苣苔属(苦苣苔科)一新种

贡山异叶苣苔　新种　图 1ＷｈｙｔｏｃｋｉａｇｏｎｇｓｈａｎｅｎｓｉｓＹｉｎＺ .ＷａｎｇｅｔＨ .Ｌｉ,ｓｐ .ｎｏｖ .Ｆｉｇ .1 .ＡｆｆｉｎｉｓＷ .ｔｓｉａｎｇｉａｎａｅ (Ｈａｎｄ . Ｍａｚｚ.)Ａ .Ｗｅｂｅｒ,ａｑｕａｓｅｐａｌｉｓｌａｔｉｏｒｉｂｕｓ,ｃｏｒｏｌ     

Vegetation‐environment relationships in Atlantic European calcareous grasslands

Abstract. The relationship between vegetation and environment was investigated for calcareous grasslands in a region in the west of Spain, France, Britain and Ireland defined by climatic criteria. Vegetation was sampled using objective methods and data collected on soils, land cover, location and management. Climate data were obtained from an available database. Examination of the first axis of vegetation variation as defined by Detrended Correspondence Analysis (DCA) showed a gradient from the Irish and British samples to those from France. The Spanish samples formed a separate group on the second axis. The species composition along the gradients is discussed. Correlations between the vegetation gradients and environmental variables were determined. The strongest correlations with the first DCA axis were for temperature, latitude, soil organic matter, grazing and land cover. The second DCA axis was highly correlated with rainfall, altitude and land cover. The third and fourth DCA axes were more difficult to interpret but appeared to be related to land cover. The results indicate that climate factors are important at this scale, but should not be considered in isolation and that factors relating to land cover and management should also be taken into account.     

Effects of soil erosion on the floristic composition of plant communities on marl in northeast Spain

Abstract. This study explored the validity of three responses of vegetation to increased soil erosion: reduction of vegetation cover, number of species and reduced substitution of species. 201 relevés, including edaphic and geomorphological data, were surveyed in the intensely eroded Eocene marls of the Prepyrenees (NE Spain). Changes in plant species’ presence in relevés from different degradation stages were compared. The level of vegetation degradation was defined as the total phanerogam cover which, in the studied area, was correlated to the degree of soil erosion. The considered trends were validated. Reduction of phanerogam cover and species number were gradual from low to high‐eroded areas. Vegetation degradation explained 48% of the species number variance. In the later stages of degradation a significant substitution of species was not observed, only a lower frequency of occurrence of several species that appeared in the whole set of relevés. Through the process of degradation, 47% of species displayed significantly reduced frequencies as degradation increased, none showed a significant increase in frequency. It is concluded that there are no characteristic species in these plant communities that survive in the severely eroded marls. Among the few species that had increased in frequency, most only colonised favourable micro‐environments.     

肋果沙棘(Hippophae neurocarpa S.W.Liu et T.N.He)自然种群的风媒传粉特征

野外调查了青藏高原特有植物肋果沙棘的花期物候、开花式样以及风媒传粉特征,对其花粉生活力、柱头可授性及单花花粉量进行了检测.结果表明,肋果沙棘有许多适应风媒传粉的特征:雌雄异株,花小,无花冠,先叶开放,雄花萼片纵裂形成对流的"风洞",花粉近球形,单花花粉量大;雌花柱头细长捻状,伸出萼筒,授粉面大,密布乳突.花粉生活力可以持续16.5 d,柱头可授性为10～20d.肋果沙棘传粉多发生在昼夜温差大的5月中下旬,在多变的气候条件下,种群花期可持续约12～25d,但在晴朗的天气条件下具有爆发性的集中开花机制,是对恶劣条件的适应.重力玻片法检测表明,离花粉源15m左右远的地点花粉密度最大,135m仍能接收到花粉,夜间接收到的花粉数量也很可观,这些研究结果表明,该植物集中在有利的晴朗天气昼夜进行长距离的风媒散粉,能较好地适应青藏高原的复杂环境.     

叶螨及两种替代食物对尼氏真绥螨发育和繁殖的影响

在温度25 ℃、相对湿度80％条件下,以油茶花粉、二斑叶螨和腐食酪螨3种食物饲喂尼氏真绥螨,研究不同食物对尼氏真绥螨生长发育和繁殖的影响.结果表明：尼氏真绥螨虽能取食腐食酪螨的卵,但因摄食量不足导致不能完成正常发育;而取食油茶花粉和二斑叶螨能正常完成发育,并进行繁殖.取食油茶花粉的尼氏真绥螨全世代发育历期、雌螨寿命、产卵历期、平均每雌总产卵量分别为6.18 d、24.97 d、16.72 d和23.03粒,取食二斑叶螨的尼氏真绥螨分别为5.67 d、25.72 d、18.17 d和25.38粒;以二斑叶螨为食的尼氏真绥螨发育快,寿命和产卵历期长,平均每雌产卵量高.以油茶花粉和二斑叶螨为食的尼氏真绥螨实验种群数量动态均呈上升趋势,其中以油茶花粉饲养的种群趋势指数最高（I=14.28）,以二斑叶螨饲养的种群加倍时间最短（t=3.5201 d）.     

太白杜鹃一新变种

本变种与原变种var.purdomii的区别在于叶片较大,长4～11cm,宽2～55cm,上面疏生淡黄色长柔毛,边缘密生青白色和淡黄色缘毛,柔毛和缘毛易脱落;叶柄较长(长1～3cm);总花梗较长(长达18cm)。河南:嵩县,白云山国家森林公园,玉皇顶,海拔2100m,1993年7月4日,张益民、吴立宏93088(模式标本Typus存于河南农业大学植物标本室;同号模式标本存于中国科学院昆明植物研究所);内乡,宝天曼国家自然保护区,扫帚场,海拔1600m,1989年7月28日,张益民、温德臣89006。根据调查,本新变种常生于山之阴坡和湿度较大的地方。叶普遍较大,革质化程度稍低。生长状态叶上…