太行山片麻岩山区造地边坡植被恢复过程中植物多样性与土壤特性的演变

为了探究太行山片麻岩山区造地后坡面植被的演变规律,以太行山片麻岩山区不同治理年限的坡面为研究对象,研究了坡面的植被状况与土壤理化性状。结果表明:随着治理年限的增加,坡面植被覆盖度、地上生物量和植物种类均显著增加,分别由第2年的18.00%、67.52 g/m~2、10种增加到了第7年的92.67%、379.91 g/m~2、19种。随治理年限的增加,坡面土壤的理化性质得到改善,土壤容重由第2年的1.40 g/cm~3降低到了第7年的1.29 g/cm~3,土壤有机质含量由第2年的4.91 g/kg增加到了第7年的7.18 g/kg;土壤总孔隙度、全氮、碱解氮、速效钾含量分别由第2年的47.15%、0.17 g/kg、16.10 mg/kg、26.58 mg/kg增加到了第6年的51.60%、0.61 g/kg、62.18 mg/kg、57.40 mg/kg,在第7年又分别降低为51.42%、0.50 g/kg、37.80 mg/kg、30.90 mg/kg。坡面植被多样性与土壤多项理化性状表现为显著相关。随着治理年限延长,造地后的坡面土壤的理化性质发生改变,土壤有效养分增多,持水能力增强,植被覆盖度与植物种类均显著增加,植物多样性稳步提高,生态环境得到有效改善。     

太行山南麓山区不同植被恢复类型土壤理化和细根结构特征

在干旱半干旱地区,由于水分匮乏、土壤贫瘠等因素,将形成一定的裸地斑块,而这些斑块极易造成水土流失、滑坡等灾害,而具有不同植被覆盖的林地则能有效的保持水土。为完善干旱半干旱地区不同植被恢复类型下土壤理化和细根特征,选择太行山南麓山区具有代表性的裸露地、草地、荆条地、侧柏地、栓皮地和刺槐地等植被恢复类型,比较了各植被恢复类型下的土壤养分、粒径及细根状况等差异。研究表明:1)相对于裸露地,有植被覆盖的植被恢复类型拥有良好的土壤及细根状况。2)在不同植被类型中,刺槐林的有效氮转化速率较高;侧柏林有较高的细根参数;草地能够提高土壤中可吸收的磷组分。3)林地类型和土层均对土壤中含水率、黏粒、细根生物量和比根长产生极显著影响(P0.001)。4)各植被类型的对于土壤斑块的利用能力不同;不同植被类型中土壤及细根状况变化量具有一定的相似性,研究为生态恢复中植被类型的合理布局提供了新思路。     

不同经营模式对蒙古栎次生林叶功能性状和土壤理化性质的影响

植物功能性状是连接植物与环境的桥梁,能反映植物对外部环境的适应机制。以黑龙江省哈尔滨市丹青河实验林场3种经营模式下的蒙古栎天然次生林为研究对象,对其叶功能性状进行研究,探讨叶功能性状与土壤理化性质间的关系,对于理解植物对环境的适应机制及植物群落的构建具有重要意义。研究结果表明:(1)除土壤全钾、速效钾、有机碳含量外,不同经营模式下的土壤理化性质相差不大;(2)不同经营模式下的叶功能性状差异较大,目标树经营模式的单叶面积极显著大于综合抚育模式和无干扰模式(P0.01),目标树经营模式的叶氮、叶有机碳含量极显著小于综合抚育模式和无干扰模式(P0.01);单叶面积与叶氮含量、叶有机碳含量间均存在极显著负向相关关系(P0.01),叶氮含量与叶有机碳含量间存在极显著正向相关关系(P0.01);(3)土壤有机碳对单叶面积、叶氮含量、叶磷含量、叶有机碳含量均有显著影响。可见,不同经营模式下的蒙古栎天然次生林自我恢复能力较强,在采取不同程度的抚育后均未造成林地土壤养分的损失,土壤有机碳是影响不同经营模式下蒙古栎天然次生林叶功能性状变异的主要因素,蒙古栎天然次生林群落通过功能性状的耦合协调或组合来适应环境,植物功能性状对土壤理化性质的响应是一个长期的过程,仍需加强长期监测和更多研究。     

Pyrroloquinoline scaffold-based 5-HT6R ligands: Synthesis,quantum chemical and molecular dynamic studies,and influence of nitrogen atom position in the scaffold on affinity

Based on pyrroloquinoline scaffold bearing 5-HT_2C agonists, a series of arylsulfonamide derivatives of 1H-pyrrolo[2,3-f]quinoline and 1H-pyrrolo[3,2-h]quinoline, substituted at position 3 with tetrahydropyridine, were synthesized and evaluated in vitro for their affinity for 5-HT₆ receptors. A structure–activity relationship study showed that the 1H-pyrrolo[3,2-h]quinoline scaffold was more favorable for 5-HT₆R binding than the 1H-pyrrolo[2,3-f]quinoline one, suggesting dependence upon the type of condensation of the pyrrole and quinoline rings. As revealed by quantum-chemical calculations and molecular dynamic studies, position of the quinoline nitrogen atom in the planar pyrroloquinoline skeleton might affect the spatial orientation of the arylsulfonyl fragment, as a result of structure stabilization by internal hydrogen bonds.     

不同时期喷施多效唑对花生生理特性、产量和品质的影响

为确定高产条件下不同花生品种的最佳化控时期,以小花生品种‘花育20’(HY20)和大花生品种‘花育25’(HY25)为试验材料,研究了多效唑(PBZ)不同喷施时期对花生根系活力、叶绿素含量、叶片保护酶和碳、氮代谢酶活性,以及荚果产量和籽仁品质的影响.结果表明:不同时期喷施PBZ均提高了2个品种花生在结荚期的叶绿素含量、根系活力,以及叶片超氧化物歧化酶、过氧化物酶、过氧化氢酶、蔗糖合成酶、蔗糖磷酸合成酶和磷酸烯醇式丙酮酸羧化酶活性,降低了丙二醛(MDA)含量以及硝酸还原酶、谷氨酰胺合成酶、谷氨酸脱氢酶和谷氨酸合成酶活性,且PBZ喷施时间越早效果越明显.在饱果期,HY25的各指标以主茎高25cm时喷施PBZ的效果最好,但HY20在主茎高25 cm时喷施PBZ的保护酶活性降低,化控时间过早导致植株早衰,叶绿素含量、根系活力以及碳代谢酶活性也略低于CK,HY20的指标以主茎高30 cm时喷施PBZ效果最好.适宜时期PBZ处理提高了2个品种的荚果产量和经济系数,提高了脂肪含量和油酸相对含量以及O/L值.高产条件下,HY25和HY20的最适多效唑处理时期分别为花生主茎高25和30 cm左右.     

Polyhydroxyalkanoates: Properties and chemical modification approaches for their functionalization

Polyhydroxyalkanoates (PHAs) have become an attractive biomaterial in research in the past few years due to their extensive potential industrial applications. Being long chain hydroxyl fatty acid molecules, the PHAs are hydrophobic in nature, and have less functional groups. These features limit their applications in various areas. To enhance their usage, these polymers may need to be modified including surface and chemical modifications. Such modifications may alter their mechanical properties, surface structure, amphiphilic character and rate of degradation to fulfil the requirements for their future applications. Chemical modifications allow incorporation of functional groups to PHAs that could not be introduced through biotechnological methods. These chemically reformed PHAs, with enhanced properties, could be used for broad range of applications. This review aims to introduce different chemical modification approaches including some recent methods that had not been explored or discussed so far for PHAs as possible technologies for widening the range of product and application potentials. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:29–41, 2018     

An optimized protocol for large‐scale in situ sampling and analysis of volatile organic compounds

Chemical ecology is an ever‐expanding field with a growing interest in population‐ and community‐level studies. Many such studies are hindered due to lack of an efficient and accelerated protocol for large‐scale sampling and analysis of chemical compounds. Here, we present an optimized protocol for such large‐scale study of volatiles. A large‐scale in situ study to understand role of semiochemicals in variation in mating success of lekking blackbuck was conducted. Suitable methods for sampling and statistical analysis were identified by testing and comparing the efficiencies of available techniques to reduce analysis time while retaining sensitivity and comprehensiveness. Solid‐phase extraction using polydimethylsiloxane, analysis using a semiautomated detection of retention time and base peak, and statistical analysis using random forest algorithm were identified as the most efficient methods for large‐scale in situ sampling and analysis of volatiles. The protocol for large‐scale volatile analysis can facilitate evolutionary and metaecological studies of volatiles in situ from all types of biological samples. The protocol has potential for wider application with the analysis and interpretation methods being suitable for all kinds of semiochemicals, including nonvolatile chemicals.     

Spatial correlations between browsing on balsam fir by white‐tailed deer and the nutritional value of neighboring winter forage

Associational effects, that is, the influence of neighboring plants on herbivory suffered by a plant, are an outcome of forage selection. Although forage selection is a hierarchical process, few studies have investigated associational effects at multiple spatial scales. Because the nutritional quality of plants can be spatially structured, it might differently influence associational effects across multiple scales. Our objective was to determine the radius of influence of neighbor density and nutritional quality on balsam fir (Abies balsamea) herbivory by white‐tailed deer (Odocoileus virginianus) in winter. We quantified browsing rates on fir and the density and quality of neighboring trees in a series of 10‐year‐old cutovers on Anticosti Island (Canada). We used cross‐correlations to investigate relationships between browsing rates and the density and nutritional quality of neighboring trees at distances up to 1,000 m. Balsam fir and white spruce (Picea glauca) fiber content and dry matter in vitro true digestibility were correlated with fir browsing rate at the finest extra‐patch scale (across distance of up to 50 m) and between cutover areas (300–400 m). These correlations suggest associational effects, that is, low nutritional quality of neighbors reduces the likelihood of fir herbivory (associational defense). Our results may indicate associational effects mediated by intraspecific variation in plant quality and suggest that these effects could occur at scales from tens to hundreds of meters. Understanding associational effects could inform strategies for restoration or conservation; for example, planting of fir among existing natural regeneration could be concentrated in areas of low nutritional quality.