Priming effects: Interactions between living and dead organic matter

In this re-evaluation of our 10-year old paper on priming effects, I have considered the latest studies and tried to identify the most important needs for future research. Recent publications have shown that the increase or decrease in soil organic matter mineralization (measured as changes of CO₂ efflux and N mineralization) actually results from interactions between living (microbial biomass) and dead organic matter. The priming effect (PE) is not an artifact of incubation studies, as sometimes supposed, but is a natural process sequence in the rhizosphere and detritusphere that is induced by pulses or continuous inputs of fresh organics. The intensity of turnover processes in such hotspots is at least one order of magnitude higher than in the bulk soil. Various prerequisites for high-quality, informative PE studies are outlined: calculating the budget of labeled and total C; investigating the dynamics of released CO₂ and its sources; linking C and N dynamics with microbial biomass changes and enzyme activities; evaluating apparent and real PEs; and assessing PE sources as related to soil organic matter stabilization mechanisms. Different approaches for identifying priming, based on the assessment of more than two C sources in CO₂ and microbial biomass, are proposed and methodological and statistical uncertainties in PE estimation and approaches to eliminating them are discussed. Future studies should evaluate directions and magnitude of PEs according to expected climate and land-use changes and the increased rhizodeposition under elevated CO₂ as well as clarifying the ecological significance of PEs in natural and agricultural ecosystems. The conclusion is that PEs - the interactions between living and dead organic matter - should be incorporated in models of C and N dynamics, and that microbial biomass should regarded not only as a C pool but also as an active driver of C and N turnover.     

大专英语教学中活动教学法的运用

介绍了平衡活动教学法的核心理论及在课堂上的具体操作过程,并阐明这一教学法对于培养学生的语言实际应用能力为教学目的的专科英语教学确将发挥重要作用。     

新疆玛纳斯河流域植被变化的特征与归因

植被覆盖是旱区生态环境状况的重要表征和直接反馈。气候变化和人类活动干扰加剧的背景下，亟需明确植被覆盖的变化状况和归因，但当前研究缺乏对各驱动因子贡献率的量化。为此，选取新疆玛纳斯河流域为研究区域，基于1982—2015年NDVI和气候数据，在分析植被时空变化格局的基础上，量化了气候变化和人类活动的贡献率。1982—2015年，流域年均NDVI值呈东高西低、北高南低的空间分布格局。34年间NDVI呈显著上升趋势（+0.60%/10 a），但存在年际变异；1995年发生突变，1982—1995年NDVI显著上升（+1.50%/10 a），而1996—2015年显著下降（-0.40%/10 a）。较1982—1995年，1996—2015年的植被变化是气候变化和人类活动共同作用的结果，其对植被变化的贡献率分别为52%和48%。采取的贡献率量化方法有效地甄别了不同因子对植被变化的影响，量化的结果表明玛纳斯河亟需采取措施进行植被管理以提升其生态环境状况。     

耕作模式对土壤生物活性与养分有效性及冬小麦产量的影响

为探讨长期玉米秸秆还田下不同耕作模式对土壤生化性状及冬小麦产量的影响,从2011年10月至2016年6月连续5个冬小麦生长季进行田间定位试验。设4个耕作处理,分别是连续旋耕秸秆不还田(RT)、连续旋耕秸秆还田(RS)、连续深耕秸秆还田(DS)及前2年旋耕秸秆还田第3年深耕秸秆还田(TS)。与RT相比,连续5年秸秆还田显著提高0~10、10~20和20~30 cm土层土壤有机碳、无机氮、速效磷、速效钾含量;土壤脲酶、蛋白酶、硝酸还原酶和蔗糖酶活性及土壤微生物多样性分别提高23.1%~59.3%、13.2%~40.7%、14.1%~28.8%、10.9%~19.5%和31.9%~42.5%。秸秆还田使各土层变形菌门、硝化螺旋菌门及放线菌门的相对丰度显著提高,而酸杆菌门相对丰度则显著降低。与DS及TS相比,RS显著提高0~10 cm土层土壤养分状况及生物活性,10~30 cm土层则显著降低。连续旋耕至第3年,无论秸秆还田与否,小麦均表现减产;DS与TS处理则表现持续增产,平均年增产3.2%和3.9%。本研究表明在黄淮海东部地区,秸秆还田条件下,2年旋耕后接1年深耕的耕作模式有助于改善耕层土壤质量和提高冬小麦生产力。     

Vineyard Compost Supplemented with Trichoderma Harzianum T78 Improve Saline Soil Quality

Understanding soil degradation is especially important in the Mediterranean Region where desertification is a serious problem, and soil salinization is one of the causes. Salinity reduces soil quality, limits crop productivity and brings on long term soil degradation. Therefore the restoration of degraded soils is necessary to reduce land degradation, improve soil fertility and achieve a sustainable food production. The addition of compost supplemented with the beneficial microorganism Trichoderma harzianum isolate T78 to saline soils (NaCl) was studied to determine the impact on soil microbiology, which is the key to restore and rehabilitate degraded soils. The selected Trichoderma harzianum isolate T78 showed high salt tolerance despite the low osmotolerance of the genus Trichoderma . Increasing salt concentration reduced Trichoderma sp colony‐forming units (CFU) from natural soil and adversely affected soil microbial biomass C as well as dehydrogenase, β‐glucosidase, phosphatase and urease activities. Simultaneous amendment of the saline soil with compost and inoculation with T. harzianum T78 improved the soil microbiological quality; the number of T. harzianum T78 CFU did not decrease as NaCl increased. As T. harzianum strain T78 is salt tolerant, increasing the relative abundance of this specific strain would contribute to the rehabilitation of saline soils. Vineyard composts supplemented with T. harzianum T78 represent a promising approach for the treatment and improvement of saline soil properties. Copyright © 2016 John Wiley & Sons, Ltd.     

藏山羊若干行为观察研究

对全放牧藏山羊若干行为进行了昼夜连续24小时跟踪观测研究。结果表明,藏山羊昼夜采食时间为541.37±93.65分。反刍为280.21±67.59分,睡眠为173.30±45.92分,游走为136.15±62.79分,站立为133.35±34.88分,其他行为占175.62±53.18分。采食、游走、站立及其他行为多发生在白天,反刍和睡眠多在夜间。反刍与采食的时间比例为0.52:1。藏山羊母性较强,好喜戏和觅群,少争斗。此外,藏山羊还有搔痒、打喷嚏、啃食异物等异常行为。研究结果,可供藏山羊的培育和饲养管理作为参改。     

苹果秋梢对树体生理活性的影响及其防衰功能

选用３年生盆栽新红星苹果为试材，研究了苹果秋梢生长对叶片衰老和树体生理活性的影响。结果表明，苹果秋梢能减缓植株其他部分叶片的衰老，增加叶片的生理活性，且能提高根系活力。     

抗菌肽天蚕素B突变体ABP-S1基因在E.coli中的融合表达

利用绿色荧光蛋白 (GFP)基因与天蚕素 B突变体 ABP- S1基因的融合基因 ,构建了 2个原核表达载体 p Am GS1和 p Bm GS1,转化表达宿主菌 E.coli BL 2 1(DE3)和 E.coli BL 2 1(DE3) p L ys S。结果 ,p Am GS1未能得到转化子 ,而p Bm GS1的转化子高效表达了融合蛋白 ,经 IPTG诱导 ,SDS- PAGE检查 ,融合表达产物最高可占菌体总蛋白的49.45 %。表达产物经包涵体复性 ,柱层析初步纯化 ,通过平板抑菌试验 ,对大肠杆菌、金黄色葡萄球菌、铜绿假单胞菌、变形杆菌以及鱼类重要的致病菌嗜水气单胞菌等多种革兰氏阳性、阴性菌表现出较强的抗菌活性     

重视和加强“第二课堂”对大学生思想政治教育的作用

本文提出第二课堂”是新时期加强大学厂{思想政治工作的有效途径，分析了第二课堂”具有明显的针对性、主动性、灵活性和时代感的特点，它是服务十学生主体的发展，符合青年学生的特点和认识规律。文章还论述了通过第二课堂”开展大学生思想政治工作的内容、形式、方法、手段，并就如何健全第二课堂”思想政治工作的机制提出了建议。     

Microbial and Enzyme Activities of Saline and Sodic Soils

Salinization and sodication are abiotic soil factors, important hazards to soil fertility and consequently affect the crop production. Soil salinization is of great concern for irrigated agriculture in arid and semi‐arid regions of the world; sodicity is characterized by an excessively high concentration of sodium (Na) in their cation exchange system. In recent times, attention has been turned to study the impacts of these factors (salinity and sodicity) on soil microbial activities. Microbial activities play central role in degradation and decomposition of soil organic matter, mineralization of nutrients and stabilization of soil aggregates. To understand the ecology of soil system, therefore, it is important to be conversant with the soil microbial activities, which show quick response to little change in the soil environment. Microbial activities (generally measured as C–N dynamics, soil respiration–basal respiration, or CO₂ emission), microbial abundance, microbial biomass, quotients (microbial and metabolic) and microbial community structure, and soil enzymes have been considered as potential indicators to assess the severity of the land degradation and the effectiveness of land use management. Therefore, it is important to synthesize the available information regarding microbial activities in use and management of salt‐affected soils. The reclamation and management of such soils and their physico‐chemical properties have been reviewed well in the literature. In this review, an attempt has been made to compile the current knowledge about the effects of soil salinization and sodication on microbial and enzyme activities and identify research gaps for future research. Copyright © 2015 John Wiley & Sons, Ltd.