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排序方式: 共有133条查询结果,搜索用时 31 毫秒
1.
Tree replacement patterns in subalpine Abies-Betula forests,Wolong Natural Reserve,China 总被引:1,自引:0,他引:1
Vegetation in canopy gaps of two old-growth Abies-Betula forest stands, one with bamboo the other without, was measured. The structure of gap vegetation at each site was used to derive tree replacement probabilities. Transition probabilities indicate different tree replacement trends in forests with bamboo compared to those without. Projected compositions show Betula to be the most abundant species in bamboo stands while Abies remains most abundant where bamboo was absent. A dense bamboo sward seems to reduce the probability of Abies filling gaps by inhibiting establishment and growth of seedlings. Bamboo preempts space after canopy gap formation by increasing shoot production which reduces opportunities for establishment and growth of other woody species. Differences in dispersal ability and longevity of Abies and Betula appear to be important factors contributing to their coexistence forests with a small canopy gap disturbance regime. 相似文献
2.
E. Friar G. Kochert 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,82(6):697-703
Summary Bamboo species are difficult to identify because flowering material is seldom available and taxonomy is of necessity based on vegetative characters. To evaluate the utility of restriction fragment length polymorphism (RFLP) analysis in bamboo systematics and germplasm screening, a library of random genomic probes from a Phyllostachys nigra PstI library was constructed. Probes from the library were used to screen bamboo germplasm consisting mostly of temperate bamboos of the genus Phyllostachys. RFLP variation was abundant, and species-specific patterns were readily obtained. Chloroplast DNA showed little variation among the bamboo accessions analyzed. 相似文献
3.
小竹鼠在我国仅分布于云南西部热带亚热带地区。主要生活于山坡稀树灌丛、阔叶林、橡胶园及居民点附近。在盈江县分布于海拔300-950米地带。取食、休息、繁殖主要在洞道内。洞系由洞口、取食道、趋避道、窝及“厕所”组成。食物主要有棕叶芦、芦竹及三叶橡胶等18种,尤喜食橡胶树主根,因而对橡胶树危害很大。13号标本中雌7雄6。在盈江每胎2-3只,以2只为多。成年小竹鼠过独居生活,雌雄各有自己的洞系。 相似文献
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E. Friar G. Kochert 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(2-3):265-270
Phylogenetic and taxonomic difficulties are common within the woody bamboos, due to their unique life cycle, which severely limits the availability of floral characters. To addresss some of these problems, 20 species of woody bamboos in the genus Phyllostachys were analyzed using nuclear restriction fragment length polymorphisms (RFLPs). The RFLP data were used to generate genetic distances between all pairs of taxa and to examine the degree of genetic variation within and among bamboo species. The genetic distances were also used to create dendrograms of accessions and species. These trees supported the current division of the genus into two sections and provided some information on the thorny taxonomic problems in this group. We show that RFLPs can be used for species identification and the delineation of species limits. 相似文献
7.
Over a period of 7 years the biology and phenotypic variability of Chusquea culeou were studied at 5 locations in cool temperate forests of southern Argentina. Excavated rhizomes had an average of 1.1 successful rhizome buds, and an average of 2.1 years elapsed between successive generations of rhizomes. Rhizome buds usually develop within the first four years after a rhizome forms. Height, volume and weight of a culm can be calculated from its diameter 1 m above the ground. Culm size, length of foliage leaf blades, and pattern of secondary branching differed among study sites. Dead culms were numerous and commonly remained erect for more than 7 years after dying. New culm shoots appear in spring and reach full size within a few months. Shoots can grow more than 9 cm/day. Less than half of the shoots survived a year; most were killed by moth larvae. Multiple primary branch buds emerge through the culm leaf sheaths in the second spring. The mean number of branch buds at mid-culm nodes varied between 34.8 and 81.5, and the mean number of primary branches was between 22.8 and 40.8. Number and length of branches, and number and length of foliage leaf blades at each node is related to the position of the node on a culm. Most branches grow about 3 cm and produce 1 to 3 foliage leaves annually. Foliage leaf blades generally live 2 years or more; few survive 6 years. Relative lengths of foliage leaf blades and their spacing along a branch permit recognition of annual cohorts.Both gregarious and sporadic flowering have been reported, and every year a few isolated plants flower and die. Length of the life cycle is unknown. Seedlings require up to 15 years to produce culms of mature size. Foliage branches may live more than 23 years, and culms may survive 33 years. Extensive loss of new shoots to predation suggests that gregarious flowering may be driven by a need to escape parasitism. C. culeou clumps expand slowly. Average annual rate of increase of the number of live culms in a clump was 4.6%. Methods of seed dispersal are undocumented. A dense stand of Chusquea culeou had an estimated phytomass of 179 tons/hectare (dry weight), 28% of which was underground. Net annual production was about 16 t/ha dry weight. 相似文献
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9.
Jih-Shiou Liu Yau-Heiu Hsu Tzu-Yu Huang Na-Sheng Lin 《Journal of molecular evolution》1997,44(2):207-213
Satellite RNA of bamboo mosaic potexvirus (satBaMV) is a linear RNA molecule which encodes a 20-kDa nonstructural protein.
Sequences of seven different satBaMV isolates from bamboo hosts in three genera showed 0.7% to 7.5% base variation which spanned
the whole RNA molecule. However, the putative 20-kDa open reading frame was all preserved in these isolates. The phylogenetic
relationship based on the nucleotide sequence did not show particular grouping of satBaMV from the host in one genus; neither
was the grouping of satBaMV evident by location of sampling. Putative secondary structures of the 3′ untranslated regions
showed a basic pattern with conserved hexanucleotides (ACCUAA) and polyadenylation signal (AAUAAA) located in the loop regions.
Although the satBaMV-encoded 20-kDa protein is a nonstructural protein, its predicted secondary structure contains eight-stranded
β-sheets which may form ``jelly-roll' structure similar to that found in capsid protein encoded by satellite virus of panicum
mosaic virus.
Received: 26 June 1996 / Accepted: 9 September 1996 相似文献
10.
根癌农杆菌对单子叶植物竹子的细胞转化 总被引:2,自引:0,他引:2
陈霓;徐杏阳;洪树荣;吴立廉;王诗云 《武汉植物学研究》1991,9(3):201-205
本实验证明:具有重要经济价值的禾本科植物——竹子(bamboo)可被根癌农杆菌转化。在经有毒性的根癌农杆菌C_(580、A_(348)感染的竹子材料中,分别测到了专性的胭脂碱和章鱼碱,而对照处理及无毒性的根癌农杆菌VirA~-_(211)mx、NTI感染的竹子材料中,测不到冠瘿碱。 相似文献