茂兰喀斯特漏斗森林群落结构研究

通过设样地调查,对茂兰喀斯特漏斗森林进行群落结构研究.森林群落内共有维管植物61科116属153种,其中蕨类植物7科10属11种.常绿树种占群落全部植物的50%~65.38%.乔木层中,乔木的个体/种水平均低,优势种不明显;小径级树木分布数量大,群落结构稳定.茂兰喀斯特漏斗森林在植物区系上表现出明显的热带性.     

南方桉树人212林雨雪冰冻经济损失评估与分析

针对雨雪冰冻灾害未满5年轮伐期的4类重灾林分开展经济损失评估.结果表明:在萌蘖经营前,不同重灾林分的经营成本与产量均有所差异,只有4年生的重灾林分木材利润为正值,其平均净收入和平均利润分别为16 907.20元·hm-2和2 480.85元·hm-2;其余类型的重灾林分因为经营期较短,木材产量较低不足以完全抵销经营期内的成本.在萌蘖经营中,亦只有4年生重灾林分的收益高于未受灾林分(CK),其平均净现值(NPV)、内部收益率(IRR)和产出投入比(B/C)分别达18 114.00元·hm-2、57.95%和3.52,比最低分别高98.56%,39.21%和65.79%.不同类型萌蘖经营的NFV和IRR与木材价格和木材产量成正比,而与经营成本和贴现率成反比,IRR不随贴现率的变化而变动.本文还就如何提高灾后桉树人工林的经济效益进行了商讨.     

外生菌根真菌及其接种白皮松生长对煤矸石胁迫的反应

研究外生菌根真菌铆钉菇菌菌丝在煤矸石提取液中的生长模式,并对接种和未接种的白皮松在不同比率煤矸石混合基质中的生长和存活作探索性研究。结果表明:铆钉菇菌在85%煤矸石提取液中生长良好。虽然煤矸石环境抑制了菌丝的发展,降低了苗木的接种率,但对于接种后的幼苗,其在不同比率煤矸石混合基质中的各项生长指标都优于未接种幼苗。其中,接种幼苗干质量和侧根数,显著多于未接种幼苗。纯煤矸石的环境中真菌和植物都很难生存和发展,但与少量的黄土(15%)混合后,各项生长指标都得到显著改善。这个结果说明,为了保证煤矸石生态治理工程中的成功,有必要在矸石中混合一定土壤以保证生物技术的顺利实施。     

Patterns of synonymous codon usage bias in chloroplast genomes of seed plants

Codon usage in chloroplast genome of six seed plants （Arabidopsis thaliana, Populus alba, Zea mays, Triticum aestivum, Pinus koraiensis and Cycas taitungensis） was analyzed to find general patterns of codon usage in chloroplast genomes of seed plants. The results show that chloroplast genomes of the six seed plants had similar codon usage patterns, with a strong bias towards a high representation of NNA and NNT codons. In chloroplast genomes of the six seed plants, the effective number of codons （ENC） for most genes was similar to that of the expected ENC based on the GC content at the third codon position, but several genes with low ENC values were laying below the expected curve. All of these data indicate that codon usage was dominated by a mutational bias in chloroplast genomes of seed plants and that selection appeared to be limited to a subset of genes and to only subtly affect codon usage. Meantime, four, six, eight, nine, ten and 12 codons were defined as the optimal codons in chloroplast genomes of the six seed plants.     

Antimicrobial anthraquinones from Morinda angustifolia

Investigation on Morinda angustifolia resulted in the isolation of a new anthraquinone, 1,8-dihydroxy-2-methyl-3,7-dimethoxyanthraquinone (1), along with five known analogues, lucidin 3-O-beta-primeveroside (2), 1,3-dihydroxy-2-methylanthraquinone (3), lucidin- omega -ethyl ether (4), lucidin-omega-butyl ether (5) and damnacanthol (6). The new compound demonstrated significant antimicrobial activity against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Sarcina lutea, Candida albicans and Saccharomyces sake.     

Soil desiccation for Loess soils on natural and regrown areas

In the Loess Plateau, soil desiccation has become a serious problem for forest and grass vegetation. Soil desiccation leads to the formation of a dried soil layer (DSL). This paper presents the results of research carried out in the central part of the Loess Plateau. The objective of the research was to produce a statistically supported set of indicators for evaluating soil desiccation of forestlands, to present a heuristic idea for soil desiccation and to supply scientific support for replacing farmland with forest or grass in the Loess Plateau and other regions of China. Here, we suggest that more attention should be paid to soil desiccation and its effects on the ecosystem of the region in the future. The results showed that natural Quercus liaotungensis forestlands (NQF) retained more water content than regrown Robinnia pseudoscacia forestlands (RRF). Significant DSLs were formed in the RRF but not in the NQF. A possible reason for no formation of DSL in NQF could be due to the presence of an arbor–shrub–herb stand structure and large humus and litter accumulation, which increased the natural forest's (NF) adaptability to the environmental conditions. Soil water content in the north-facing slope was significantly larger than in the south-facing slope. DSLs formed in the 0–500 cm layer of the south-facing slope. When slope gradient was greater than 25°, soil water content deceased sharply and showed significant difference compared with 9°, 15° and 20° (P < 0.05). So, we conclude that plant species, aspect and slope angle could be the predicators for the formation of DSLs. The analysis on soil physical properties of 0–60 cm layer indicated that plant species, aspect and slope angle also have significant effects on bulk density, porosity, plant-available capacity, and hydraulic conductivity, especially in the 0–20 and 20–40 cm layers. In the NQF and RRF with north-facing slope, soil physical properties were improved.     

聊红槐在园林绿化中的应用前景

聊红槐(Sophora japonica L. cv. Liaohong)为豆科落叶乔木国槐的新变种,其花色鲜艳、花多繁密、新奇美丽,具有较高的观赏价值,并具有耐寒、耐旱、抗污染、适应性强、吸收有害气体等优良特性。适宜在公园、居住区以及厂矿等绿化中推广应用,是具有广阔发展前途的园林绿化树种。     

择伐对生长季针阔混交林土壤分室呼吸的影响

采用LI-8100土壤CO2排放通量全自动测量系统和与之配套的土壤温度、湿度传感器,对小兴安岭带岭林业局东方红林场观测样地不同强度择伐后,测定林地生长季土壤分室呼吸速率以及10 cm土深处的温度和湿度,探讨生长季土壤各分室呼吸的年际变化.结果表明:枯枝落叶层土壤呼吸速率生长季平均值呈逐年增加的趋势,观测期内枯枝落叶层土壤呼吸速率均值与采伐强度呈二次相关的关系(R2=0.806);根系呼吸速率生长季平均值逐年变化较复杂,差异较大,观测期内根系呼吸速率均值与采伐强度亦呈二次相关的关系(R2=0.415);矿质土壤呼吸速率生长季平均值呈逐年增加的趋势,与采伐强度相关性不显著.土壤温度和湿度是影响土壤分室呼吸速率变化的2个重要因素.枯枝落叶层和矿质土壤层是控制择伐后林地土壤呼吸变化的关键组分.为降低择伐后林地CO2排放增加速率,应选用中小强度(52%以下)的择伐作业.     

计算机网络系统感应雷防护研究

介绍了接地、感应雷和直击雷的概念,同时对感应雷的侵入途径和计算机网络系统感应雷防护作了详细阐述,这对其它弱电系统感应雷防护也具有参考价值.     

尤溪县观赏竹资源及其开发利用初探

对尤溪县竹类植物资源进一步进行调查,发现文献未记录的竹类9种,加上原有已记录的竹种,尤溪县境内共有竹类11属64种,其中具有观赏价值的有11属39种。阐述了每种观赏竹的生态与观赏特性、园林配置及应用特点。针对尤溪园林绿化存在的问题,提出发展观赏竹的前景和对策,为合理开发与利用观赏竹资源进行了有益的探索。