红花尔基沙地樟子松天然林枯立木特征分析

[目的]了解沙地樟子松天然纯林中枯立木的数量及空间结构特征,探究枯立木形成的原因,为樟子松林的保护和经营提供依据。[方法]在沙地樟子松天然纯林中设置2块1 hm~2的大样地,用全站仪对样地中所有胸径大于5 cm的立木进行定位并进行全面调查;对调查样地的基本特征,枯立木的数量特征及径级分布进行了分析,提出了用于表达林分中枯立木微环境的活立木比的概念,并采用林分空间结构参数一元分布和二元分布分析方法,对枯立木与其最近4株相邻木的关系进行分析。[结果]2块不同密度的樟子松天然纯林下更新幼苗和枯立木数量相差较大,密度较小(样地1)的样地更新幼苗和枯立木较少,而密度较大的样地(样地2)中枯立木达到200棵,林下更新幼苗数量达到15 280株·hm~(-2);樟子松天然纯林样地内枯立木主要以小径级木为主,胸径集中在11 cm以下;样地1枯立木径级连续分布,幅度较窄;样地2中的枯立木径级幅度较宽,但在20 22 cm缺刻,有2株大于23 cm的枯立木;2块样地中枯立木的分布格局均为随机分布,样地1中枯立木周围的4株相邻立木大多为活立木,且胸径较枯立木大;样地2中,只有一半的枯立木周围的最近4株立木为活立木,且有三分之一以上的枯立木胸径不是最小的,枯立木有连续分布的现象。2块样地中枯立木的角尺度-大小比数二元分布特征的差异不明显,而角尺度-活立木比二元分布特征和大小比数-活立木比二元分布特征差异明显,样地1中枯立木的最近4株随机分布于其周围的相邻木为活立木且胸径大于枯立木的比例明显高于样地2,而枯立木最近4株随机分布于其周围的相邻木有枯立木的比例明显小于样地2。[结论]樟子松天然纯林枯立木以小径级林木为主,枯立木的数量与林分密度相关,林木竞争是林木死亡的主要原因,密度过大也会产生病虫害,因此,对天然樟子松纯林要进行适度经营,保持合理密度。     

中国原木进口与木质林产品出口的动态分析

1992-2014年中国木质林产品出口总值增长37.7倍,年均增长率达到17.94%;而原木进口总值增长25.6倍,年均增长率为15.89%。原木进口与木质林产品出口存在相同的增长趋势。文中以原木进口总值和木质林产品出口总值数据为基础建立VECM模型,并通过正交化脉冲响应函数和方差分解分析证明,中国原木进口与林产品出口之间存在正相关关系,原木进口显著推动了中国木质林产品的出口,但原木的供应不足也将制约林产品出口规模的进一步扩大。因此,缓解原木供求矛盾和优化林产品出口结构成为推动林产品贸易健康发展亟待解决的问题。     

Effects of thermal-time artificial scarification on the germination dynamics of black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) seeds

The aim of this study was to determine the efficiency of methods for the artificial scarification of black locust seeds based on the influence of the air and liquid nitrogen temperatures. Three populations were selected for the analyses: a managed tree stand, a selected seed stand and a seed orchard. Samples of 200 seeds (4 × 50) were randomly selected. Before scarification, the seeds were stored at ?70 °C for 24 h. Nine different scarification treatments were evaluated. To calculate the germination capacity and the dynamics of germination, observations were made on days 3, 5, 7, 10 and 14 after treatment. For statistical analyses, we used repeated measures analysis of variance. The obtained results indicated that the highest scarification efficiency for black locust seeds occurred in the treatment in liquid nitrogen and in an air temperature range of 85–90 °C. The provenance of seeds had a significant effect on the dynamics of germination. Thermal methods and the use of liquid nitrogen can be alternatives to the labour intensive methods of cutting the seeds or using measures that require specialised equipment.     

裂叶桦和欧洲白桦叶片形态特征及相关基因表达特性比较

为了探寻欧洲白桦变种裂叶桦的叶缘分裂机制。以2种桦树为研究对象,在叶片形态特征和解剖特征观测的基础上,进行了顶芽及叶片叶尖、裂片及凹缺等不同组织部位相关基因表达定量分析、内源激素IAA含量测定以及IAA活体标记的GUS染色分析。结果表明,裂叶桦叶片两侧叶缘自叶基到叶尖分裂出由大到小3~4个裂片,叶背面的叶脉呈明显的管状隆起,叶宽、平均二级脉间距、主脉横切面积等分别较欧洲白桦大了21.12%、12.64%、21.46%。BpmiR164s及靶基因的组织表达特性分析结果证明,BpmiR164-2及靶基因BpCUC2与裂片的形成关系密切,是裂叶性状产生的主要调控基因。生长素输出载体BpPINs基因的组织表达特性分析结果证明,6个基因中只有BpPIN2和BpPIN5在裂叶桦的叶尖、裂片及顶芽等组织器官中呈现上调表达。内源激素IAA的活体标记发现,在顶芽、幼叶中IAA的含量较高,而在叶片中,叶尖、叶齿及裂片处是激素的高表达部位,利用液相色谱—质谱联用仪(LC-MS)对2种桦树的上述不同组织部位的生长素测定也证明了激素的上述分布特点。综合上述,裂叶桦裂片产生是激素在叶脉、叶缘的极性运输及相关基因调控的结果。      

学术期刊编辑应妥善处理专家外审修后再审稿件

对作者按外审专家审稿意见进行修改的修改稿再次进行学术把关,已受到国内外期刊编辑的重视。本文从提高论文学术质量、促进审稿人与作者的双向学术交流和减轻终审负担3个方面分析了稿件修后再审的必要性,按修后再审稿件的评判、退修和复审3个步骤阐述了编辑应如何处理外审阶段修后再审稿件。最后就修后再审中可能存在的增加审稿人负担和延长稿件发表时滞问题进行讨论。     

5种入侵植物提取物对2种芒果病原真菌的抑制作用

以马缨丹(Lantana camara Linn.)、薇甘菊(Mikania micrantha Kunth.)、含羞草(Mimosa pudica Linn.)、假臭草(Praxelis clematidea Cassini.)和三裂叶蟛蜞菊(Wedelia trilobata(L.)Hitchc.)为材料,采用菌丝生长速率法研究这5种入侵植物乙醇提取物对芒果炭疽菌Colletotrichum gloeosporioides和蒂腐菌Botryodiplodia theobromae Pat的抑菌活性,并利用气相色谱-质谱(GC-MS)联用技术分析假臭草的主要抑菌物质。菌丝生长速率法的实验结果表明:5种入侵植物提取液对2种病原真菌均具有抑菌活性,且抑菌效果随浓度的增加而增强;其中马缨丹提取物对蒂腐菌抑制效果最好,其EC50为10.39 g·L~(-1),假臭草提取液对炭疽菌和蒂腐菌均有较强的抑菌效果,EC_(50)分别为14.70 g·L~(-1)和14.77 g·L~(-1)。采用气相色谱-质谱(GC-MS)联用法分析鉴定了假臭草提取物中的14种化学成分,其中4,5,6,7-四甲氧基黄酮、熊果苷和1,2,4-环己三醇这3种物质占总含量的81.85%。     

空心村废弃宅基地复垦策略

废弃宅基地复垦是空心村整治的重要内容,而复垦后耕层土壤质量往往不如人意。笔者以提高废弃宅基地复垦耕层质量为目标,从复垦方向的确定、拆除工程的实施、田块设计、耕层土壤工程重构、培肥改良5 个方面对复垦策略进行优化,提出废弃宅基地复垦包括耕层土壤工程重构和肥力重构两个重要步骤,并对废弃宅基地耕层土壤快速培肥进行了探讨。     

No consistent daily variation in DNA methylation detected in <Emphasis Type="Italic">Populus nigra</Emphasis> leaves by methylation-sensitive amplification polymorphism analysis

DNA methylation, an epigenetic mechanism used by cells to control gene expression, has an important biological role in plant development and environmental fitness. Since plant DNA methylation is closely related to environmental conditions, variation during the day is expected. Here, in genetically identical plants of Populus nigra clone N46, DNA methylation changes in leaves over a 24 h period were detected using the methylation-sensitive amplification polymorphism method. The results showed different DNA methylation patterns in mature poplar leaves: not only in individuals at the same time, but also in samples at each of the six time during the day. In addition, night samples had a higher percentage of methylation than in morning samples. However, no statistically significant differences were found among the samples gathered at different times. Similar results were obtained for three other P. nigra clones with different genetic backgrounds. Real time qPCR showed that the DNA methyltransferase genes Pt-MET1 and Pt-SOM1 involved in CG DNA methylation in poplar were stable over a 24 h period in leaves of P. nigra N46 compared with circadian-controlled genes. That could be part of the reason that methylation of CCGG sites is stable in those leaves. That DNA methylation differed even in genetically identical plants indicates the specificity of DNA methylation changes in their genomes. No statistically significant differences in methylation changes were found between day and night, suggesting that DNA methylation is more stable than expected and is unlikely to be involved in circadian regulation in plants.     

县域农田土壤铜、锌、铬含量空间变异特征及其影响因子分析

【目的】研究县域农田土壤重金属空间变异特征及影响因子,可为保护农田环境质量提供有效信息。【方法】本研究利用地统计学和GIS相结合的方法,对四川省双流县623个土样铜、锌、铬含量空间结构、分布特征进行分析,并在此基础上对其影响因子进行了探讨。【结果】(1)农田土壤铜、锌、铬含量属于中等变异强度,其最大值与最小值之间的差异明显;(2)土壤铜、锌、铬含量的空间相关距离分别为28281、45613、45892m,且具有中等程度的空间自相关性,其空间变异受结构性和随机性因子的共同影响。【结论】普通Kriging插值表明,土壤铜、锌、铬含量的空间分布趋势较为接近,高值区主要集中在县境内西北部。影响因子分析表明,土壤铜含量在不同地形条件下呈极显著差异;成土母质对铜和锌含量空间变异有重要影响;有机肥使用量是影响土壤铜、锌、铬含量空间变异的重要因子;社会经济条件中,农业基础条件和化肥使用量对土壤铜、锌、铬含量空间变异的影响程度最高。     

静电场对三角梅插穗生根及几种生理生化指标的影响

在三角梅种苗智能化快繁中,设置0、30、60、90 kV/cm四种静电场处理,探讨对三角梅插穗生根及生理生化指标的影响。结果表明:三角梅插穗生根期间,在0～60 kV/cm静电场范围内插穗的成活率、根系活力、根鲜重、可溶性糖含量、POD酶活性随着电场强度的增强而提高,其中在不定根诱导期插穗的吲哚乙酸氧化酶活性也随着电场强度的增强而提高。90 kV/cm静电场处理插穗的成活率、根系活力、可溶性糖含量、POD酶活性、吲哚乙酸氧化酶活性反而下降;30～90 kV/cm静电场处理插穗的可溶性蛋白含量均高于对照,且随着电场强度的增强而增加。方差分析表明,60 kV/cm静电场处理生物学效应好,其成活率、根系活力、根鲜重均显著高于对照,是三角梅插穗生根的最佳静电场处理;90 kV/cm电场处理不利于三角梅插穗生根及生理生化代谢,说明了静电场对三角梅插穗生根及生理生化的影响存在着电场极限。