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941.
942.
《Scandinavian Journal of Forest Research》2012,27(1-4):87-98
The risk for damage associated with spruce bark beetle attacks on living trees was estimated in 12 forest districts in the Nordic countries during three years. Pheromone‐baited traps and trees were used. Five groups of three traps were deployed annually on fresh spruce clear‐fellings in each district. The mean catches within districts and years ranged from 950 to 46000 beetles per trap group. The standard error averaged 15 % of the mean catch. One tree was baited annually at each of five other sites in each district. The mean number of trees colonized by Ips typographus in each district and year ranged from 0 to 5 per site. The standard error was high, averaging 44% of the mean. Inventories of tree mortality within the districts yielded values ranging from 0 to 150 killed trees per km of spruce forest edge. There was a strong linear correlation between mean catches in traps and log‐transformed tree mortality (r=0.82). The correlation between colonization success at tree‐baiting sites and tree mortality was weaker (r=0.59), owing to one deviant observation. The results indicate that pheromone traps and baited trees may be used to assess the risk for damage caused by Ips typographus. 相似文献
943.
记述了贺兰山的4种野生有蹄类动物——马麝、马鹿、岩羊、鹅喉羚的经济价值及目前的种群动态变化,对贺兰山野生有蹄类动物的种群致危原因进行了分析,并据此提出了相应的保护管理建议。 相似文献
944.
试验于2011年夏季进行了桂花不同基质(林地表土、炉渣土、农田土)、不同扦插方式(营养钵和田间苗床扦插)、插穗叶片不同处理(1片全叶、2片全叶、2片叶剪半)对比试验,结果表明:以林地表土和炉渣土扦插的生根率均较高,分别达95.5%和96.2%;营养钵和田间苗床扦插的生根率均较高,分别达95.0%和95.7%;插条叶片以留1片全叶和2片叶剪半的扦插生根率较高,分别达95.7%和95.3%。 相似文献
945.
高寒牧区绵羊高效养殖技术应用效果分析 总被引:1,自引:0,他引:1
华着 《青海畜牧兽医杂志》2012,42(6):18-19
高寒牧区发展绵羊养殖业,在很大程度上受到当地生态条件的制约。多年来畜牧业发展一直注重数量增长,投入大、产出低,由于采取自由散养放牧方式,生态植被破坏严重;并且当地的绵羊品种生长发育慢、生产性能低,绵羊出栏率低、经济效益差,绵羊生长发育的营养需求和一般饲料中的营养成分也不能得到满足;而高寒牧区严酷的自然环境条件下,牧草产草量低、品质差,又缺乏秸秆加工技术,秸秆利用率较低,造成绵羊饲料不足,畜牧业的生产现状和存在的实际问题已成为当地经济发展的瓶颈。推广应用高寒牧区绵羊高效养殖技术,提高畜牧业生产水平的任务迫在眉睫。 相似文献
946.
947.
We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, regeneration status, and population structure by a selective approach with asystematic sampling design. A total of 74 quadrats (each for 25 m × 25 m,spaced at intervals of 150 200 m) were sampled along established transect lines following the homogeneity of the vegetation. Vegetation data including cover-abundance, height, diameter at breast height (DBH), and numbers of seedlings and saplings of woody species were analyzed using Excel spreadsheet, Shannon Weiner diversity index, and PAST version 1.62. A total of 87 vascular plant species of 74 genera and 36 families were recorded. The dominant family was Fabaceae represented by 16(18.39 %) species of 13 genera. Shannon Weiner diversity and evenness were 3.67 and 0.82, respectively, which showed that the area was endowed with rich floral diversity evenly distributed. The vegetation structure, as quantified by cumulative diameter class frequency distribution,plotted as an interrupted inverted-J-shape pattern with a sharp decreasein the 2nd diameter class. This indicated poor vegetation structure. The diameter classes frequency distributions of selected species plotted infour general patterns i.e., interrupted Inverted-J-shape, J-shape,Bell-shape and Irregular-shape. In conclusion, although the area showedhigh floral diversity and evenness, woody species including Sterculea setigera, Boswellia papyrifera, and Pterocarpus lucens showed lowest recruitment of seedlings and saplings. 相似文献
948.
949.
为选育优质小果型青皮西洋南瓜良种,以引进西洋南瓜品种的分离后代中选育的自交系A156为母本、A257为父本进行杂交,于2008年育成早熟、优质、丰产的小果型西洋南瓜新品种贝栗。经品种比较试验、多点中间试验和生产示范试验,结果表明,该品种全生育期89d,春季栽培果实发育期约35d,平均单果质量0.7kg,667m2产量2100kg左右;果实扁圆形,青皮,果肉黄色,平均肉厚2.0cm,质粉味甜,种子粒小、白色;每株坐果5~7个,生长势较强;耐低温、高温,抗逆性强,适应性广。 相似文献
950.