Individual resource allocation to vegetative growth and reproduction in subgenus <Emphasis Type="Italic">Cyclobalanopsis</Emphasis> (<Emphasis Type="Italic">Quercus</Emphasis>, Fagaceae) trees

The resource allocation for vegetative growth and female reproduction in three tree species of subgenus Cyclobalanopsis (Quercus, Fagaceae), i.e., Q. salicina, Q. sessilifolia, and Q. acuta, were examined on a per-individual basis in two consecutive reproductive seasons, in order to test whether these trees fit the predictions of the masting hypotheses about resource matching versus resource switching. Since the three Quercus species have a biennial fruiting habit, it takes 3 years for the observation of two reproductive events. Female flower and acorn production per tree were investigated by using a seed-trap method and a numerical analysis of seed dispersal. The net production of each individual was estimated as the sum of the annual increase in the dry mass of vegetative organs and reproductive investment per tree. In the data analyses, the three species were pooled, since all 12 sample trees of the subgenus apparently showed masting in the same year, with no exceptions. Female flower and acorn production per individual tree changed considerably between years. The net production per tree increased with tree size, but did not differ between years. Therefore, the reproductive allocation (proportion of a plant’s annual assimilated resources which are used for reproduction) differed dramatically between years. On the other hand, within a year, the reproductive allocation increased with increasing net production per tree. These results suggest that the switching of resource allocation between years within an individual are occurring in subgenus Cyclobalanopsis species, and the intensity of the switching increases with increasing tree size.     

海甘蓝的初步研究

首次报道了海甘蓝Ｃｒａｍｂｅａｂｙｓｓｉｎｉｃａ在我国的引种栽培情况,并对海甘蓝体细胞染色体进行计数。经过２年的选育,海甘蓝去壳种子的含油量为４４．４７％;芥酸含量高达６２．５０％,比国外报道的结果提高了２．５％－７．５％;未去壳种子的硫甙含量为７１．５１－８２．２１μｍｏｌ／ｇ。理论产量１４８５－５２５０ｋｇ／ｈｍ＾２（９９－３５０ｋｇ／亩）。研究结果表明：在我国海甘蓝有希望成为一种新型的高芥酸     

Endozoochory by free-ranging, large herbivores: Ecological correlates and perspectives for restoration

Seed dispersal via ingestion and defecation by large herbivores provides a possible aid for ecological restoration of plant communities, by connecting source communities of target species with habitat restoration sites. It is also a possible threat due to invasion of weeds, grasses or exotic species. Insight into the factors determining internal seed dispersal could therefore improve the management of grazed ecosystems.

We recorded viable seed density in cattle, sheep and pony dung samples and monitored dung pat colonisation in the field. In addition, we counted the distribution of dung pats in plots spread over all habitat units in our study site.

The three herbivore species appeared to disperse large quantities of many species (61 in total) from a variety of plant families, monocots as well as dicots. The density of viable seeds in herbivore dung and the colonisation of dung pats were positively correlated with Ellenberg nitrogen indicator values and seed supply, but not with seed mass or shape.

The results imply that many seeds are dispersed from high productive to low productive parts of the grazed area. In free-ranging systems, we therefore recommend enclosure and separate management of plant communities on nutrient-poor soils with high conservation interest. For habitat restoration sites we recommend integrated grazing only with target plant communities on nutrient-poor soils and not with plant communities on nutrient-richer soils.     

外果皮厚度和种子大小对五种栎属橡子扩散的影响

动物对种子的扩散和贮藏是一个复杂的生态学过程,常常受到种子特征的影响。有关种子特征如何影响动物对种子扩散,许多研究结果并非完全一致。我们于2009 年9 月在黑龙江东方红林场野外和围栏内释放五种栎属橡子(Quercus mongolica,Q.serrata var. brevipetiolata,Q. aliena,Q.variabilis 和Q. liaotungensis),研究种子特征对鼠类(Apodemus peninsulae, Clethrionomys rufocanus 和Tamias sibiricus)扩散和埋藏橡子的影响。野外释放结果表明:橡子大小和外果皮厚度显著影响鼠类对橡子的扩散和埋藏。鼠类偏向扩散和埋藏种皮厚的大橡子,种皮薄的小橡子则多被原地取食。种皮厚的大橡子扩散距离显著高于种皮薄的小橡子。然而,只有外果皮的厚度显著影响围栏内花鼠对橡子的扩散和埋藏,橡子大小并非主要的影响因素。种子特征影响种子扩散的效应可能在种群和群落水平上存在差异。     

西双版纳热带森林的土壤种子库储量及优势成分

作为西双版纳热带森林土壤种子库生态学系统研究的首次报道,本文采用野外样带取样与萌发实验相结合的方法,探讨了当地１类季节雨林（番龙眼、千果榄仁林）和３类次生森林（山黄麻林、中平树林、半人工林）的土壤种子库储量及其优势成分。结果发现,中平树林和山黄麻林的土壤中蕴藏着十分丰富的种子,在厚度为１０ｃｍ的表层土壤中,它们的种子密度分别高达２９９４５±２２６７粒／ｍ２和２４７４０±２２７５粒／ｍ２。而季节雨林和半人工林土壤种子库中的种子密度仅为５９０５±２０２粒／ｍ２和３３４５±４３８粒／ｍ２。草本植物无论是在种类还是个体数量上都是这几类森林土壤种子库的优势成分,但随着森林演替年龄的增加,其所占比例有所减少。     

种子活力与蛋白质关系的研究进展

对种子活力的研究是目前种子生理学研究的热点,近年来对种子活力的机理的研究有了新的突破。本文主要叙了种子活力与蛋白的关系研究进展,包括种子活力与贮藏蛋白的关系、种子种力与热激蛋白等逆激蛋白的关系、种子活力与泛肽、钙调蛋白的关系等,并探讨了与种子活力有关的逆激蛋白之间的同源性。     

Apomixis is not developmentally conserved in related, genetically characterized Hieracium plants of varying ploidy

Apomixis is facultative in characterized members of the genus Hieracium. The three components that comprise the apomictic mechanism include apospory followed by autonomous embryo and endosperm formation. The time of aposporous embryo sac initiation and mode of embryo sac formation are different in Hieracium piloselloides (D3) and Hieracium aurantiacum (A3.4). Genetic studies have shown that a single dominant locus encodes all three components of apomixis in both species (Bicknell et al. 2000). We histologically examined a range of related, genetically characterized apomictic Hieracium plants derived from D3 and A3.4 to assess conservation of the apomictic mechanism in different genetic backgrounds. The plants varied in ploidy, and also in the amount of DNA introduced from sexual Hieracium pilosella (P4). An apomictic hybrid from a cross between the two apomicts was also examined. The developmental processes observed in the parental apomicts were not conserved in the examined plants and alterations occurred in the components of apomixis. One plant also exhibited adventitious embryony. The results show that other genetic factors can modify apomixis with respect to time of initiation, spatial location, and mode of developmental progression. Both the apomictic locus and the modifiers are essential for efficient penetrance of the trait in Hieracium. Some of the findings in Hieracium correspond with observations in Ranunculus and this is discussed in terms of models for apomictic development and the control of apomixis in crops. Received: 21 June 1999 / Revision accepted: 17 November 1999     

铜尾矿对小麦生长发育和生理功能的影响

通过盆栽实验,分析了铜陵铜尾矿对小麦生长发育和生理功能的影响。结果表明,小麦种子能在铜尾矿上萌发,但发芽率和发芽速率均小于正常土壤中播种的小麦,高比例尾矿抑制小麦的株高,尾矿降低叶绿素含量,但对叶绿素a/b无影响,与对照组相比,尾矿组根系表现为变短变粗,须根数减少,尾矿能增加小麦根和茎叶部分生物量,且能明显提高根冠比,在尾矿胁迫下,小麦叶片的细胞膜透性和游离脯氨酸含量随尾矿比例增加而增大,可作为鉴定植物相对抗性的指标。     

Potential invasion of China by exotic insect pests associated with tree seeds

A total of 39 insect species, mostly seed chalcids in the genus Megastigmus (Hymenoptera), but also midges (Diptera), are listed as potential seed-borne invaders of Chinese conifers. Although the number of native seed insects per conifer genus does not differ between China and other biogeographical regions, there are significantly fewer seed insects associated with each conifer genus in China than potential invaders. The eventual success of the invaders is likely to depend on the presence of native Chinese conifers that are congeneric with the original host, or on the presence of the original host as an exotic. When a substantial entomofauna is already associated with cones, competition for seed resources may limit the potential impact of invaders because seed insects are usually the last organisms to colonize the cone. A survey of 26 fir species, both native and introduced to Europe, showed that overall seed infestation by five species of exotic chalcids is negatively correlated to levels of damage by native insects, except on the original hosts of the chalcids. Similar patterns are hypothesized for native firs, spruces, Douglas firs, and larches in China. Uncontrolled importation of seeds and nuts of broad-leaved trees could also facilitate the introduction of seed chalcids, seed bruchids, tortricid moths and nut weevils into China. Only six species of seed chalcids are present in China, out of the 72 known to attack broad-leaved seeds over the world.