Competitive and facilitative relationships among three shrub species,and the role of browsing intensity and rooting depth in the Succulent Karoo,South Africa

Abstract. The nearest‐neighbour technique is used to infer competition and facilitation between the three most abundant species in a semi‐arid region of western South Africa. Relationships among the shrubs Leipoldtia schultzei and Ruschia robusta, which are leaf‐succulent members of the Mesembryanthemaceae (‘mesembs’) and Hirpicium alienatum a non‐succulent Asteraceae, were compared on two adjacent sites with different histories of browsing intensity. Competition was more prevalent and more important than facilitation. The only evidence for facilitation was found at the heavily‐browsed site where the palatable Hirpicium was larger under the unpalatable Leipoldtia. Generally the prevalence and importance of competition was reduced at the heavily‐browsed site. Strong evidence was obtained for intraspecific competition in each of the three species; also, competition was evident between the two mesembs, where Leipoldtia was competitively dominant over Ruschia, although neither species inhibited Hirpicium. Minimal competition between the mesembs and the asteraceous shrub was interpreted in terms of differentiation in rooting depth, and competition within the mesembs, in terms of overlap in rooting depth. The mesembs had the bulk of their roots in the top 5 cm of soil, while the asteraceous shrub had the bulk of its roots, and all its fine roots, at greater depths. The shallow‐rooted morphology of the mesembs is well adapted to utilize small rainfall events, which occur frequently in the Succulent Karoo, and do not penetrate the soil deeply. Modifications of existing methods are applied for analysing nearest‐neighbour interactions.     

长苞铁杉的核型分析及其分类学意义

本文首次分析了特产我国的长苞铁杉亚属(Subgen. Paleotsuga)的代表种长苞铁杉Tsuga longibracteata的核型,它全由中部和近中部着丝粒染色体组成,核型公式为K(2n)=24=22m 2sm,属“lA”类型。第12号染色体具“长着丝点区域”。染色体相对长度组成为2n=12M_2 10M_1 2S。作者发现铁杉亚属(Subgen. Tsuga)植物的核型全为“2A”类型。胞核学资料支持对长苞铁杉亚属和铁杉亚属的划分并表明前者(长苞铁杉)较为原始。长苞铁杉应隶于长苞铁杉亚属、长苞铁杉组。     

中国繁缕属的一些分类问题

研究了36种中国产繁缕属(Stellaria)植物,根据模式材料或仅根据原描述,将已合格发表的1组、1系、12种、4变种和1变型首次归并到有关各类,依次列举入异名录中,其中有1移属。讨论了各种错误鉴定,同时对于选择性状、设想进化过程和分布记录均有讨论。     

云南兔Lepus comus G.Allen的分类订正——包括两个新亚种的描记

云南兔Lepus comus G.Allen是云贵高原和滇西山地目前发现的唯一的一种野兔,初由G.M.Allen（1927）根据采自云南西部腾冲的标本命名。其后,国内外学者（包括G.M.Allen本人在内）对云南兔究竟是一独立种或为高原兔Lepus oiostulus（Hodgson）的一个地理亚种意见纷纭（罗泽珣,1981;高耀亭等,1964;Allen,1938;Ellerman et al.,1951;Angermann,1967;Corbet,1978。我们曾对国内有关单位所收藏的这两个类群的100余号标本进行较详细的对比研究。发现云南兔在形态上与高原兔确有明显区别,在分布上又有同域现象,因而主张仍应将云南兔保持其原定种的种级地位;同时,又查对了采于各地的云南兔所有标本,发现云南北部（丽江）至中部（景东、景谷）标本以及云南东部、南部和贵州西部标本都有异于滇西地模标本,且占有不同的地理分布区。经研究,应属两个新的亚种。其中,云南东部,南部和贵州西部的新亚种,为纪念先师彭鸿绶先生毕生献身于云、贵、川的科学考察事业和他的指导与培养,特以彭先生之姓氏命名,以资纪念。     

Revision ofVerbesina sect.Pseudomontanoa (Asteraceae)

Verbesina sect.Pseudomontanoa is revised. The last treatment of the group byRobinson & Greenman (1899) recognized 5 species; the present treatment recognizes 12 species, 3 of which (V. breedlovei, V. cronquistii andV. olsenii) are described as new. A key to species, phyletic diagram and distribution maps are provided.     

Body shape and differences between species

The variation of body shape among prosimians is reviewed. Special emphasis is placed on the selective advantages, that is the mechanical reasons, to which variants of the locomotor apparatus can be traced back. There are differences found in the cheiridia, but at present they cannot be explained in terms of mechanics; there is nearly no knowledge about the mechanical meaning of their diversity. Myological characteristics of taxa can be explained mechanically, but this has not yet been done. Well known are variations of body proportions. These discriminate higher taxa, and are largely coincident with the often-used locomotor categories. In spite of this, there are only few sound arguments about the real biomechanic value of characteristic proportions for a given locomotor mode. What is known on this field, is reviewed. Progress can be made only, if the mechanical conditions, set by postural behavior and locomotion, are understood completely. The subtle distinctions between lower taxonomic units can normally be identified only on the basis of detailed and quantified analyses of movements on one hand, and of biometrics on the other. In the few cases in which such studies have been made, the differences of morphology fit to the mechanical requirements of locomotion which also differ only in quantitative details.     

条鳅亚科鱼类一新属新种

本文描述了云南省条鳅亚科鱼类一新属和一新种。根据形态特征并结合区系间的相互关系,探讨了属的分类地位。     

新疆贝母属的订正

本文根据所收集到的标本和有关文献资料,对新疆贝母属进行了整理。归并9种和21变种。确认新疆贝母属有7种,包括一新分布种,裕民贝母F．stenanthera。     

山茶科紫茎属和舟柄茶属的系统学研究

本文对山茶科紫茎属和舟柄茶属进行了深入细致的系统学研究,藉助形态学、古植物学、孢粉学,细胞学和解剖学资料澄清了两属的分合问题,证实两属在各方面具有较大相似性,并且各分类特征存在广泛的联系而无法分开,从而赞同H．K．Airy Shaw,J．R．Sealy及S．A.Spongberg的主张,即将这两属合并。在此基础上本文提出了世界范围广义紫茎属下分类系统。属下新系统根据花柱合生程度、花序类型,苞片与萼片的形状以及两者的相对长度等特征,分为两个亚属,五个组,同时对该属种类进行修订。该属共有23种5变种,本文发表新组1个,新名称2个,新组合9个,新异名10个,新种1个,并附有分种检索表。广义的紫茎属为东亚-北美间断分布类型,中国南部和西南部是该属的起源中心和高度分化中心。根据化石资料推断,该属起源于早白垩纪,在第三纪以前于整个劳亚古陆上呈广泛而连续的分布,后因冰川及造山运动的影响,从而形成现在的分布格局。