宁夏青铜峡库区植被资源及保护问题

青铜峡库区是宁夏唯一有天然森林植被、珍稀候鸟、水生生物与广阔水域组成的自然保护区,素有“黄河森林公园”之称。1967年4月青铜峡水利枢绍建成以后,蓄水量猛增,库容量扩大,水位不断升高,汛期洪水倒灌,水库     

Fires and pyrogenic successions in the forests of the south Baikal region

The southern coast of Baikal is characterized by the most humid climate in the Baikal region. Precipitation falls mainly on summer, thus reducing the actual of fire occurrence in mountain forests of the region. However, since 1989 the fire occurrence has been increased and disastrous crown fires have become more frequent, especially in the west. It is shown that fire occurrence is a function of the number, duration of rainless periods and monthly sums of rain precipitation, which have large amplitude of changes from year to year. Progressive pyrogenic successions in dark coniferous forests take place mostly without usual replacement by small-leaved tree species at the expense of successful regeneration of Pinus sibirica (in the western Khamar-Daban mountains) and Abies sibirica (in the central part) on the burnt areas during 15–25 years.     

Coral successions in Upper Tortonian reefs in SE Spain

Martin, Jose M., Braga, Juan C. & Rivas, Pascual 1989 07 15: Coral successions in Upper Tortonian reefs in SE Spain. Lethaia , Vol. 22, pp. 271–286. oslo. ISSN 0024–1164,
During the Upper Tortonian (Upper Miocene), the Almanzora river corridor, a small Neogene basin in SE Spain, harboured coral reefs growing in three different environments: in fan deltas, beyond the influence of coarse terrigenous sedimentation; in the abandoned lobes of a delta complex; and on coastal margins. All of these reefs are composed of several successive beds, each of which may be made up mainly of Porites embedded in silt or of an initial Porites level followed by a silt-free Tarbellastraea level on top. Porites may be associated with corallines. This structure is interpreted as being the result of an ecological succession repeated over and over again. A pioneer association consisting mainly of Porites . by colonizing the substrate and continuing to grow through relatively adverse silt-deposition conditions, prepares the ground for Tarbellastraea to take over. A return to the previous conditions halts the growth of the Tarbellastraea colonies and the Porites association once more establishes itself in the silt, or else the renewed rate of deposition is sufficiently heavy to suffocate the whole bioconstruction.* Ecological succession. coral reefs, Tortonian, southeast Spain .     

Characteristics of the Vegetative Growth of Bacillus popilliae

Growth characteristics of the insect pathogen, Bacillus popilliae Dutky, were studied by propagation in shaken flasks and in 2-liter fermentors. Maximal populations between 5 × 10⁸ and 2 × 10⁹ viable cells per milliliter of culture medium routinely were obtained in incubation periods of 18 to 24 hr at 30 C in a medium composed of 1.5% yeast extract, 0.6% K₂HPO₄, and 0.2% glucose or trehalose. The carbohydrate required for growth in liquid media was fermented with the formation of 2 meq of acid per mmole of carbohydrate utilized; acid products ordinarily were not subsequently metabolized. B. popilliae is an aerobe, and the amount of growth obtained varied with aeration to an optimum at oxygen absorption rates of about 0.5. Maximal populations persist in a culture for periods of only 1 to 4 hr; cessation of growth was followed immediately by rapid death of cultures, so that less than 1% of the cells remained viable after 48 hr, and viability often was lost entirely by the end of 72 hr of incubation. No cytological evidence for spore formation was observed under any growth condition. Death was not associated with lysis of the cells, although extensive granulation ultimately occurred. Continuous neutralizaiton, augmented buffering, various techniques of dialysis, or slow feeding of the carbohydrate did not markedly alleviate the characteristic death of the cultures.     

Vegetative Propagation of Pinus sylvestris

Methods for the vegetative propagation of Pinus sylvestris L. from interfascicular shoots are described. Using 5-year-old plants the outgrowth of interfascicular shoots was promoted by removal of terminal and lateral buds; this response was augmented substantially by application of cytokinin, tri-iodobenzoic acid, alar and morphactin alone and especially in combination. The rooting capacity of shoot cuttings from interfascicular shoots appeared to be largely determined by the state of growth of the stock plant. Cuttings from dormant stock plants subjected to short-day treatment followed by a period of low temperature gave the best rooting, especially when the cuttings themselves had been cold-stored prior to planting. Rooting was optimal when such cuttings were treated with a mixture of 25 mg/l of indolebutyric acid and 25 mg/l of napthaleneacetic acid as a 48 h basal soak, and were planted on a heated mistbench under extended illumination; over 90% of such cuttings could be rooted. These results are discussed in relation to bud activity, endogenous hormone levels and promoting tissue extracts also tested.     

Vegetative Production and Performance of

Aspects of the production and vegetative performance of Calluna vulgaris (heather) were examined in four areas of New Zealand between 1981 and 1983; Tongariro National Park in the North Island, together with Mount Cook National Park, the Wilderness Scientific Reserve, and Ben Callum peat bog in the South Island. The height and height/width quotient of Calluna bushes, the diameter increment of woody stems and the amount of flowers/stem all decreased with altitude. Other age-adjusted components of stem biomass were positively related to soil depth, soil moisture, soil organic content and soil pH. Biomass by direct harvest gave values between 300 g per m and 2200 g per m for plant communities with Calluna. These are similar Values to recorded from British and European heaths, although the contribution of Calluna to the total biomass was often less in New Zealand. Calluna from New Zealand has a higher proportion of wood relative to total biomass than is normally found in Britain and Europe and this is probably related to the management of British and European heaths by burning. Multiple regressions indicated that increased woodiness is associated with lower altitudes and deeper, moister soils. Woodiness tended to decrease on more organic and more acidic soils, with a corresponding increase in the proportion of green shoots. Flowering declined with increased altitude, while the proportion of green shoots relative to total biomass increased. It is suggested that the upward extension of Calluna within Tongariro National Park is limited mainly by constraints on flowering and sexual reproduction.     

楝科树木营养贮藏蛋白质的研究

采用光学和电子显微镜技术及SDS-PAGE研究了营养贮藏蛋白质(VSPs)在楝科树木中的分布和超微结构;并采用免疫印迹技术,以大叶桃花心木(Swietenia macrophylla King)的21 kD VSP的抗血清检测楝科树木VSPs的免疫相关性.结果表明,在桃花心木亚科(Swietenioideae)的树木中普遍存在VSPs,但楝亚科(Melioidae)仅部分属的树木有VSPs而椿亚科(Cedreloideae)树木没有VSPs.VSPs在同一属树木中的分布是一致的.桃花心木亚科和楝亚科树木之间的VSPs几乎没有免疫相关性,但是在桃花心木亚科中,VSPs具有相对高的同源性.楝科树木VSPs的超微结构存在一定程度的差异,这可能与VSPs的种类不同有关.VSPs的分布、超微结构和免疫相关性可能是楝科树木的一个分类特征.