Relationship between resistance to vole browsing and content of ether extract in the bark of larch species and hybrids

We determined the survival rate of tree families produced by the intra- and interspecific crossing of larch species damaged by browsing of vole (Clethrionomys rufocanus bedfordiae Thomas) and the contents of ether extracts (EE) in their bark. The average survival ofLarix gmelini var.japonica Pilg. (L. gmelini)×L. gmelini (G×G) was highest, followed by the hybridL. gmelini×L. leptolepis Gordon (G×L). The families of the hybrid G×L, which is considered suitable for silviculture in Hokkaido, Japan, showed significant differences in survival rates, suggesting that it is possible to produce improved varieties of the hybrid which are more resistant to vole browsing. The EE contents of the bark were under strong hereditary control, and the rank of the EE content among the various families hardly fluctuated between the location of the test fields. The correlation coefficient between the survival rates and the EE contents was highly significant (r=0.89,n=24,p<0.01), indicating that the EE content in the bark may be used as a possible index of resistance or susceptibility to vole browsing in larch plantations. A part of this report was presented at the 106th Annual Meeting of the Japanese Forestry Society, at Sapporo, April, 1995.     

紫色土侵蚀区种植福建柏的技术措施研究

[目的]为了加快紫色土工程侵蚀区的植被恢复,针对紫色土工程侵蚀区种植福建柏进行防治侵蚀技术措施和初植密度试验研究。[方法]试验采用裂区试验设计。[结果]试验结果表明：采取鱼鳞坑整地或等高线反坡整地,筑建土石坝,使用土壤稳定剂和铺放秸秆能够提高福建柏造林成活率及其生长量,以铺放秸秆效果更好。不同初植密度对福建柏林分生长状况有影响,考虑到造林成本和调整林分结构,认为株行距1.8m×1.8m,初植密度3086株/hm2更为合理。[结论]该试验总结了一套紫色土工程侵蚀区栽植福建柏的技术措施,在生态层面和森林培育层面都具有重要的意义。     

福建柏优树子代测定及早期选择

利用129株福建柏优树子代的苗木,在福建永安国有林场和福建仙游溪口国有林场建立优树子代测定林,对2年生试验林进行调查分析表明,不同家系在树高、地径、保存率上的差异达到极显著水平,这些差异主要由家系本身的遗传特性决定 以树高为主要指标从参试的各优树子代中,初步选出N001、R001、P001、N002、K005、L011等30个优良家系,其2年生时平均树高、地径值分别超过1 48m和1 90cm,树高、地径的平均遗传增益分别超过22%和19%;选出Ai001、Ai002、Bi001、Bi002、Ci001、Ci002等38个优良个体,2年生时平均树高、地径值分别超过2 09m和3 12cm,遗传增益分别达到80 67%和77 04% 上述初步选出的优良家系、个体表现出明显的生长优势,可用作种子园建园材料和无性繁殖材料     

焦虑情结支配下的人物形象刻画——论《无名的裘德》中淑的形象塑造

《无名的裘德》中的淑是背离维多利亚时代道德标准的新女性。她离家出走,逃离婚姻,突破传统女性的"私人空间",进入男性的"公共空间"。然而小说作者托马斯.哈代却把这一体现时代进步的新女性描述成精神不健全的女人,并为她安排了精神崩溃的悲剧命运。淑的形象塑造与作家自身的焦虑心理不无关系,体现出哈代潜意识中根深蒂固的父权思想。     

福建柏初级种子园单亲子代测定及早期选择

以福建柏初级种子园单亲子代在福建省尤溪国有林场开展子代测定试验,调查分析结果表明：不同家系在树高、地径、冠幅、胸径、材积上的差异达到极显著水平,这些差异主要由遗传因素控制。试验林6年生时平均树高、胸径和材积分别为5.12m、7.9cm和0.014 056m3。从参试家系中选出43号、4号等7个优良家系,6年生时平均树高、胸径、材积分别为5.28m、8.4cm和0.016 579m3,平均遗传增益分别为1.24%、2.75%和6.16%。从子代测定林中选出Yi001、Yi002等18个优良个体,6年生时平均树高、胸径、材积分别6.03m、14.7cm和0.043 892m3,遗传增益分别为2.94%、10.09%和28.17%。选出的优良家系、个体可用作种子园建园材料和无性繁殖材料。     

窄冠福建柏单木生物量垂直分布格局研究

通过对窄冠福建柏与福建柏原种单木生物量垂直分布格局进行研究,结果表明:窄冠福建柏树干生物量分配比例较高,符合用材林培育目标。窄冠福建柏树干生物量的分配比例比福建柏原种增加4.70个百分点。窄冠福建柏与福建柏原种单木生物量垂直分布存在差异。窄冠福建柏标准木各层树干材积呈平缓递减,冠层较长,冠层第2~4层叶量占总叶量的76.3%,第1层和第5层分别占14.9%和8.8%,各层次均有叶分布,林冠层浓密、紧凑,总叶量较均匀地分布在树冠中上、中部、中下层,冠顶、冠下层叶量偏少,总趋势是叶量分布下偏。福建柏原种标准木各层树干材积呈梯度急剧锐减,冠层主要分布在第2层和第3层,叶量占总叶量的81.7%,冠层明显上移,林冠下部(约占1/3)枝多叶少。     

Soil phosphorus fractions after seven decades of fertilizer application in the Rengen Grassland Experiment

Declining global P reserves require a better understanding of P cycling in soil and related plant uptake. On managed grasslands, application of lime and fertilizer affects not only soil nutrient status, but also plant‐species composition of the sward. We examined the P fractionation in the Rengen Grassland Experiment (RGE) on a naturally acid Stagnic Cambisol in the Eifel Mts. (Germany) 69 y after the setup of the experiment. A modified sequential Hedley fractionation was carried out for samples from 30 plots at 0–10 cm depth. Application of inorganic phosphorus fertilizer had diverse effects on inorganic (P_i) and organic P (P_o) fractions. Resin‐P_i, NaHCO₃‐P_i, NaHCO₃‐P_o, NaOH‐P_i, HCl_dil‐P_i, HCl_conc‐P_i, and HCl_conc‐P_o contents increased, while NaOH‐P_o significantly decreased and residual‐P remained unaffected. Strongest enrichment occurred in the HCl_dil‐P_i fraction, probably due to the chemical nature of the basic Thomas slag applied as P fertilizer. Without P fertilization, all fractions except residual‐P were more or less depleted. Strong P limitation of the vegetation in the limed treatments without P led to lowered contents also for NaOH‐P_i and NaOH‐P_o. However, NaOH‐P_o was largest in the Control and even exceeded the respective content in the treatments with P. It remained unclear why species adapted to a low soil P status did not access this P fraction though being P‐limited. Published theory on the availability of Hedley P fractions does neither match P exploitation nor P nutritional status of the vegetation in the RGE. Regarding NaOH‐P_o as stable and HCl_dil‐P_i as moderately labile led to a more realistic evaluation of plant P uptake. Evaluation of P availability on the basis of chemical extractions alone is questionable for conditions like in the RGE. On long‐term grassland, plant‐species composition has to be taken into account to estimate access of plants to soil P.     

Migratory flight of insect pests within a year-round distribution: European corn borer as a case study

Insect migratory flight differs fundamentally from most other kinds of flight behavior, in that it is non-appetitive. The adult is not searching for anything, and migratory flight is not terminated by encounters with potential resources. Many insect pests of agricultural crops are long-distance migrants, moving from lower latitudes where they overwinter to higher latitudes in the spring to exploit superabundant, but seasonally ephemeral, host crops. The migratory nature of these pests is somewhat easy to recognize because of their sudden appearance in areas where they had been absent only a day or two earlier. Many other serious pests survive hostile winter conditions by diapausing, and therefore do not require migration to move between overwintering and breeding ranges. Yet there is evidence of migratory behavior engaged in by several pest species that inhabit high latitudes year-round. In these cases, the consequences of migratory flight are not immediately noticeable at the population level, because migration takes place for the most part within their larger year-round distribution. Nevertheless, the potential population-level consequences can be quite important in the contexts of pest management and insect resistance management. As a case study, I review the evidence for migratory flight behavior by individual European corn borer adults, and discuss the importance of understanding it. The kind of migratory behavior posited for pest species inhabiting a permanent distribution may be more common than we realize.