辽宁地区两种菊科入侵植物与本地植物光合特性比较

为明确外来植物生理生态学性状及其与其强入侵性的关系,本研究采用野外原位气体交换参数测定的方法,分析了菊科入侵植物豚草、三裂叶豚草与其共生本地植物紫菀光合特性和叶片性状的差异。结果表明,豚草、三裂叶豚草、紫菀3种植物的光饱和点(LSP)均高于800μmol·m~(-2)·s~(-1),且两种入侵植物的LSP显著高于紫菀,表观量子效率(AQY)则显著低于紫菀;3种植物的最大净光合速率(P_(nmax))大小顺序为豚草三裂叶豚草紫菀,其中,豚草和三裂叶豚草的P_(nmax)分别比紫菀高出151.28%、82.80%,且差异显著。两种入侵植物的比叶面积(SLA)、叶片的单位质量氮含量(N_(mass))、叶片单位质量磷含量(P_(mass))、光合能量利用效率(PEUE)、光合氮利用效率(PNUE)均显著高于紫菀,但3者叶片单位质量建成成本(CC_(_(mass)))差异不显著。综上所述,辽宁的两种菊科入侵植物相对于本地共生种来说有着较高的气体交换参数和叶片特性指标,且其光合特性和叶片特性也存在着密切的联系,表现在这些菊科入侵植物有着更高的P_(nmax)、PNUE、PEUE和水分利用效率(WUE)等光合特性指标和能量利用指标,使得入侵植物能够更有效地捕获和利用环境资源,成为其得以成功入侵的原因之一。     

汶川地震灾区自然植被恢复的先锋植物特征分析

对栖息在汶川地震极重灾区部分滑坡、崩塌、泥石流等灾害体上的先锋植物的组成特征、区系成分、扩散途径和入侵植物的入侵风险进行了分析,结果表明:目前在该区域的灾害体上栖息的先锋植物有52种,隶属21科49属,以易于通过风媒传播的菊科和禾本科植物为主;先锋植物的植物区系结构与该地区原有的植物区系结构基本相同;在目前的先锋植物中有7种入侵植物,均为农田恶性杂草,会对灾害体的自然恢复产生一定的影响。     

外来植物入侵对乡土植物土壤氮素及其代谢酶活性的影响

[目的] 探究外来植物入侵对乡土植物土壤氮素及其代谢酶活性的影响的微生物学机制,为中国入侵植物的有效防治和生态管理提供科学依据。[方法] 采用田间小区控制试验,通过连续5 a的观测,研究了4种外来入侵植物（独行菜、紫茎泽兰、小飞蓬和黄顶菊）和乡土植物矮牵牛（对照）土壤氮素、酶活性及微生物学特征。[结果] ①植物入侵降低了叶片、茎和根氮含量,其大小依次表现为：矮牵牛>紫茎泽兰>独行菜>黄顶菊>小飞蓬; ②植物入侵降低了土壤氮素含量（包括全氮、硝态氮、铵态氮）,其大小依次表现为：矮牵牛>紫茎泽兰>独行菜>小飞蓬>黄顶菊;而土壤pH值呈相反的变化趋势,植物入侵增加了土壤pH值。③不同入侵植物土壤蛋白酶、脲酶和硝酸还原酶活性表现出一致的变化趋势,其中土壤蛋白酶大小依次表现为：矮牵牛>紫茎泽兰>独行菜>小飞蓬>黄顶菊,矮牵牛、紫茎泽兰、独行菜显著高于小飞蓬和黄顶菊（p<0.05）,小飞蓬和黄顶菊差异不显著（p>0.05）。④不同入侵植物土壤微生物量碳和氮表现出一致的变化趋势,其中土壤微生物量碳和氮大小依次表现为：矮牵牛>紫茎泽兰>独行菜>小飞蓬>黄顶菊,矮牵牛、紫茎泽兰、独行菜显著高于小飞蓬和黄顶菊（p<0.05）,土壤微生物量磷大小依次表现为：矮牵牛>紫茎泽兰>独行菜>小飞蓬>黄顶菊,不同植物差异均不显著（p>0.05）。⑤主成分分析结果表明,土壤硝态氮、铵态氮和pH值是入侵植物主要影响因子。[结论] 不同入侵植物可以改变土壤氮素形态、酶活性和微生物特征,较强的氮素同化能力与加速土壤氮素的转化可能是植物成功入侵的重要机制之一。     

小飞蓬对Cd的吸收特性及其EDTA效应研究

采用水培试验方法,研究了生长在赣南钨矿区尾矿上的优势植物小飞蓬(Conyza CanadensisL.)对Cd的吸收特性及EDTA对其吸收和转运Cd的影响。结果表明,在中低Cd浓度处理下小飞蓬保持良好长势,并能将更多重金属积累在地上部。小飞蓬地上部和根系的Cd含量随营养液Cd浓度的增加而增加,在Cd浓度为75μmol/L时,植物地上部Cd吸收总量达到最高,为118.87 mg。综合分析小飞蓬的生长、生理及吸收Cd的能力,在低浓度Cd污染的赣南钨矿区,选取小飞蓬作为Cd的富集植物进行修复具有良好的应用前景。EDTA的加入增加了小飞蓬体内的Cd含量,但植物的生物量受到了影响。     

贵州省关岭县和惠水县农业外来入侵植物调查与分析

贵州省地处中国西南地区，是生物多样性最丰富的地区之一，亦是受外来入侵物种威胁的重灾区之一。全面摸清外来入侵植物的发生种类及分布情况，可为外来入侵植物的预防预警和综合治理提供科学依据，提升外来物种入侵防控能力。本研究以贵州省中部的关岭布依族苗族自治县和中南部的惠水县为调查点，采用样方法对关岭县74个样点和惠水县64个样点进行实地调查，明确外来入侵植物种类、统计发生生境及分布频数等分布格局信息，并通过查阅文献分析其原产地、生活型等特征。结果表明，两个县共发现24科56种农业外来入侵植物，其中菊科物种占绝对优势（关岭占比29.55%，惠水占比33.33%），其次是苋科（关岭13.64%，惠水11.11%）、豆科（关岭6.82%，惠水6.67%）、茄科（关岭6.82%，惠水4.44%），并以一年生草本植物（关岭80.85%，惠水86.96%）为主。本研究首次在贵州省发现了逃逸至野外的柳叶马鞭草和粉绿狐尾藻自然繁殖种群，确证了其入侵特性。紫茎泽兰、三叶鬼针草、一年蓬、水花生、小飞蓬、野老鹳草、粗毛牛膝菊等广泛分布于调查样点，为两县的主要恶性外来入侵植物。农业外来入侵植物已适应当地的各种生态环境，并主要分布于荒地、农田、路边等人为干扰频繁生境，对当地的农业生态环境、人类活动和自然生态系统造成了威胁。两县外来入侵植物种类多、分布范围广、适应性强、繁殖速度快、繁殖能力强，建议尽快系统性摸清贵州省的农业外来入侵植物种类及危害程度，并加强对恶性外来入侵物种的监测和扩散动态趋势研究，为农业外来入侵植物的预防预警和综合治理提供科学依据。     

云南湿热区柠檬果园杂草组成及防除对策

根据云南省湿热区柠檬果园的杂草种类、危害特征、危害时期调查,初步明确瑞丽湿热区柠檬果园内杂草有28种,隶属于13科,其中:菊科10种,占35.71%;禾本科4种,占14.29%;茜草科、莎草科、茄科各2种,分别占7.14%;旋花科、苋科、鸭跖草科、山柑科、天南星科、十字花科、铁线蕨科、玄参科各1种,分别占3.57%。主要优势杂草为藿香蓟、阔叶丰花草、马唐、鬼针草、野茼蒿和鼠麴草。瑞丽湿热区柠檬果园危害性杂草主要集中在每年的6—8月大量发生。提出综合防除对策:1)以人工刈割的方式割除株高大于40 cm的藿香蓟、野茼蒿、鬼针草、小飞蓬等杂草。2)人工铲除柠檬植株滴水线10 cm以内范围的杂草。3)在生长初期,人工多次铲除铁线草、狗牙根和白茅等恶性杂草。4)柠檬园周边使用草甘膦除草剂防除杂草。     

水稻秸秆-薄膜连续叠加覆盖对三叶鬼针草的控制效果

入侵植物三叶鬼针草(Bidens pilosa L.)严重危害我国农林畜牧业的生产。为探究生态高效控制三叶鬼针草的方法,开展了水稻秸秆与塑料薄膜相结合覆盖控制入侵杂草的研究。试验在以三叶鬼针草和马唐[Digitaria sanguinalis(L.)Scop.]为主的自然杂草荒地进行,设置不同稻秆覆盖量(0kg·m~(-2)、1kg·m~(-2)、1.5kg·m~(-2)),于冬季进行稻秆覆盖,春季在稻秆覆盖的基础上覆盖薄膜。通过测定秸秆覆盖中期(2月12日)和薄膜覆盖中期(4月12日)的午间土壤温度、土壤相对含水量和近地表空气温湿度等环境指标和杂草生物量、种子萌发量、杂草群落结构和土壤种子库等群落指标,探究该方法控制入侵杂草的效果和机制。结果表明:冬季水稻秸秆覆盖显著降低了草地午间土壤温度、近地表空气温度、三叶鬼针草生物量和种子萌发量、优势杂草盖度和从属种的种类和数量;覆盖1.5 kg·m~(-2)稻秆的处理对各类指标的影响程度均大于1 kg·m~(-2)的处理。春季叠加薄膜覆盖导致浅层土壤高温干燥、近地表空气高温高湿;叠加薄膜覆盖处理使三叶鬼针草的土壤种子密度在0～5cm的土层内显著低于未做覆盖处理的对照,降低了79.49%;叠加薄膜覆盖处理的入侵杂草全部死亡且无种子萌发。说明冬季采用水稻秸秆覆盖,春季再叠加覆盖薄膜能有效防控三叶鬼针草的生长蔓延,在薄膜覆盖之前,覆盖1.5 kg·m~(-2)稻秆的处理对三叶鬼针草的防控效果要好于1 kg·m~(-2)的处理,在薄膜覆盖处理后,两个稻秆覆盖量处理对三叶鬼针草的防控效果均达到100%。本研究结果可为不同季节采用不同的控制方法及其组合模式防控入侵杂草的扩散提供参考。     

甘肃省牧草种子中杂草种子种类及多样性分析

为了提高甘肃省牧草种子品质,避免牧草种子中混杂杂草种子过多导致草场质量下降,对2019 —2022年甘肃省草原生态修复项目牧草种子中混杂的杂草种子进行物种鉴定及多样性分析。结果表明,供检牧草种子中混杂各类杂草24科102种。检出频次较高的杂草有26种,其中禾本科6种,藜科、蓼科杂草各4种。外来入侵物种野燕麦、反枝苋、刺苋及有毒杂草马先蒿、草地乌头需要重点监测和防控,以避免造成草地植物种群结构失衡、生态恶化、威胁家畜生存。检出杂草的生活型以草本植物为主,共98种,占牧草中全部杂草种类的96.1%;灌木仅4种,仅占牧草中全部杂草种类的3.9%。草本植物中,一年生杂草46种,多年生杂草38种,二年生杂草8种,一年生或多年生6种。     

紫茎泽兰和黄顶菊入侵对土壤微生物群落结构和旱稻生长的影响

为比较入侵植物与本地植物对土壤微生态影响的差异, 探索外来植物入侵的土壤微生物学机制, 本研究通过同质园试验, 比较分析了2种入侵菊科植物(紫茎泽兰、黄顶菊)和2种本地植物(马唐、猪毛菜)对土壤肥力和微生物群落的影响, 并通过盆栽反馈试验验证入侵植物改变后的土壤微生物对本地植物旱稻生长的反馈作用。同质园试验结果表明: 2种入侵植物和2种本地植物分别对土壤微生态产生了不同的影响, 尤其是紫茎泽兰显著提高了土壤有效氮、有效磷和有效钾含量,紫茎泽兰根际土壤中有效氮含量为39.80 mg·kg^-1,有效磷含量为48.52 mg·kg^-1。磷脂脂肪酸指纹图谱结果表明, 2种入侵植物与2种本地植物相比, 较显著增加了土壤中放线菌数量, 而紫茎泽兰比其他3种植物显著增加了细菌和真菌数量。盆栽结果表明: 黄顶菊生长过的土壤灭菌后比灭菌前旱稻株高增加113%, 紫茎泽兰也使旱稻的株高增加17%。由以上结果可知, 紫茎泽兰和黄顶菊可能通过改变入侵地土壤的微环境, 形成利于其自身生长扩散的微生态环境从而实现其成功入侵。     

紫茎泽兰叶片凋落物对入侵地4 种草本植物的化感作用

为了明确紫茎泽兰叶片凋落物对入侵地草本植物的化感作用, 研究了不同浓度紫茎泽兰叶片凋落物水提液对入侵地草本植物多年生黑麦草、白三叶、辣子草和紫花苜蓿种子萌发和幼苗生长的影响, 同时结合土培试验研究了叶片凋落物在入侵地土壤中的化感作用。结果表明, 除多年生黑麦草外, 水提液对其他3 种草本植物种子萌发均产生了显著的化感抑制作用, 且水提液的浓度越高抑制效果越强; 低浓度水提液对紫花苜蓿和辣子草的幼苗生长存在显著化感促进作用, 高浓度的水提液对除多年生黑麦草外的其他3 种植物幼苗的生长存在显著化感抑制作用, 水提液对多年生黑麦草幼苗生长的影响不显著; 土壤中按照50 g·kg^-1的比例添加叶片凋落物后, 显著抑制了白三叶的生长, 而添加活性炭后, 白三叶的单株生物量相对于未添加活性炭的处理增加71.25%, 进一步证实叶片凋落物在土壤中的化感抑制作用。这说明外来入侵植物紫茎泽兰可能通过其叶片凋落物在入侵地土壤中降解, 释放化感物质, 抑制伴生植物的种子萌发和幼苗生长, 为自身创造有利的生长环境, 实现其成功入侵和扩张。     

Conyza canadensis seed ascent in the lower atmosphere

Long-distance dispersal of wind dispersed plant seed is dependent on seeds ascending in the atmosphere's surface boundary layer (SL). However, seed dispersal research often focuses on the near-surface dynamics of abscission and deposition, with little attention paid to seed ascent and transport beyond the surface boundary layer. Our research sought to estimate the vertical seed density flux of Conyza canadensis, a common agricultural weed, in the surface boundary layer. Using a 2.7 ha field infested with Conyza canadensis, the vertical seed concentration profile was measured on 5 days, three times per day while simultaneously monitoring micrometeorological conditions to connect the mechanisms of release with the process of ascent. Vertical seed sampling was conducted from two to six meters above ground level using removable screen frames. Remotely piloted airplanes were used to quantify seed concentration at 68 and 120 m above ground level and provide a connection between near surface dynamics and dynamics higher in the SL. Seed flux density (area under seed concentration curve) decreased with height and decreased from morning to afternoon. The seed flux density was significantly correlated with mean mechanical turbulence and the interaction of mean mechanical and mean thermal turbulence, supporting earlier research of meteorological effects on seed dispersal. While fewer total seeds were collected in the afternoon, more seeds were collected at 68 and 120 m during this period and may suggest more seeds were present in the upper SL where dispersal distance may be greater. Seeds collected above the SL will potentially be carried for hours before descending, depositing seeds in the range of 2–122 m, and influencing a much greater area than seeds unable to ascend through the lower SL. While this range is very wide, the dispersal distances reported herein are several orders of magnitude greater than previously reported for plants. These findings are all the more striking since the study species has evolved resistance to glyphosate herbicide, an herbicide now widely used in soybean, cotton, and corn crops in the US. Therefore, aerial transport of C. canadensis seeds carrying genes coding for glyphosate resistance enables seed to move tens or hundreds of kilometers in a single dispersal event, a spread rate corroborated by number of cases of reported glyphosate resistance occurrences in North America.     

Extrinsic and intrinsic controls on the distribution of the critically endangered cress, Ischnocarpus exilis (Brassicaceae)

Ischnocarpus exilis, a critically endangered cress, persists in one small population in a 1m² section of a limestone tower in the South Island, New Zealand. The importance of intrinsic (seed production, dispersal ability and habitat specificity) and extrinsic factors (weed competition) acting to restrict the distribution of this threatened species were investigated with a field experiment, demographic monitoring and soil seed bank analysis. I. exilis is not confined to its present site because of high habitat specificity, but rather is limited by low seed production and limited dispersal as well as by competition with invasive weeds. Conservation management of this critically endangered species should focus on controlling weeds and on establishing new populations in suitable weed-free habitat.     

奶牛场恶臭污染物扩散规律研究

以山东省某县中等规模的3个奶牛养殖场为试验场地,以臭气浓度为监测指标,在下风向距恶臭排放源不同距离处设置采样点,对规模化奶牛养殖场恶臭污染物的下风向扩散规律及影响扩散规律的部分气象因素进行了研究,并通过数据回归得出了恶臭污染物水平扩散模型。结果表明,奶牛场恶臭污染物的排放浓度随距离的增加迅速减小,通过线性回归得出下风向同一高度处的臭气浓度与监测点距排放源的距离呈指数函数关系;对于气象条件,在27～37℃,风速小于5.4 m.s-1的范围内,风速、空气温度和空气相对湿度对恶臭污染物扩散规律的影响均显著,其中温度和风速对恶臭污染物扩散规律的影响较空气相对湿度大。     

畜禽粪便中磷释放运移特征

随着畜禽粪便农田施用量的增加,畜禽粪便中磷流失也越来越引起人们的重视。采用取样分析和室内土柱模拟的方法,研究了猪粪和鸡粪中磷在水、0.5mol·L^-1NaHCO3和土体中的释放运移特点。结果表明,猪粪经H2O和NaHCO3连续提取后,H2O提取液中无机磷（P）i占猪粪全磷（TP）的21.58%,NaHCO3提取液中Pi占猪粪TP的28.92%;鸡粪经H2O和NaHCO3连续提取后,H2O提取液中Pi占鸡粪TP的18.09%,NaHCO3提取液中Pi占鸡粪TP的17.88%;施用猪粪和鸡粪处理土柱淋溶液中水溶性总磷（TDP）、水溶性无机磷（DRP）和水溶性有机磷（DOP）浓度均随着淋溶次数的增加呈先上升后降低的趋势,施用猪粪处理磷释放速率比施用鸡粪处理快;大量施用猪粪和鸡粪后,0～30cm土体中土壤全磷（TP）和0～60cm土体中土壤速效磷（Olsen-P）的含量显著增加。     

硼污染土壤中硼释放特征及无机离子对其释放的影响

采用连续液流法研究了硼污染土壤中硼的释放动力学过程,并采用振荡平衡法就无机离子对硼释放的影响进行了研究。结果表明,（1）供试土壤硼的累计释放量随时间的延长而增大,累计释放量与全硼含量相关性不显著,而与土壤有效硼含量呈显著正相关。（2）准二级动力学方程是描述土壤硼释放动力学过程的最佳方程。（3）供试土壤各时段硼平均释放速率的自然对数与时间呈极显著的线性相关性,随时间延长反应速率不断下降。释放速率有阶段性特点,可分为快速反应阶段、中速反应和慢速反应三个阶段,释放的硼90％以上来自前两个阶段。（4）无机离子对供试土壤中硼表现出不同的释放能力,对释放量影响的大小顺序依次为：Cl^-〉SO4^2-〉CO3^2-,Na^＋〉Ca^2＋。     

内蒙古自治区鄂尔多斯高原茭蒿种子萌发特性研究

通过对内蒙古自治区鄂尔多斯高原的茭蒿与其他2种蒿属植物种子萌发特性的对比研究。结果表明,茭蒿种子质量很小,千粒重仅为(0.090 1±0.005 1)g,这种特性有利于其种子的传播;茭蒿种子质量虽然很小,但在相同条件下,与其他植物种子发芽率并没有表现出显著差异,即种子质量的大小没有对茭蒿种子的萌发造成影响。茭蒿在拥有小种子的同时又具有高的种子萌发率,是其对黄土丘陵沟谷的有效适应途径。     

The Vertical Distribution of Soil Seed Bank and Its Restoration Implication in an Active Sand Dune of Northeastern Inner Mongolia,China

Although the functions and characteristics of soil seed banks in topsoil layers have been described for various ecosystems, the spatiotemporal pattern of the seed bank in deep soil and its ecological implications for vegetation restoration of active sand dune have not been fully explored. In 2007 and 2008, seed densities with regard to dune position, soil depth and season were investigated on an active and a stabilized sand dune of northeastern Inner Mongolia, China. Seeds in the 0–10 cm topsoil layer accounted for 60% of total soil seed bank on the stabilized sand dune, while more than 40% of seeds were stored in the 50–100 cm layers on the active sand dune. Seed density declined significantly with soil depth on the stabilized sand dune, but it was relatively constant across the 0–100 cm soil profile on the active sand dune. Seed density fluctuated with soil depth on the active sand dune suggesting that seeds were either relocated upward or downward over time. Seeds of annual non‐psammophytic species accounted for the majority of soil seed bank on the stabilized sand dune, while pioneer psammophytes contributed more to the soil seed bank of the active sand dune. Our data suggest that seeds in the deep soil layers of active sand dunes account for a large proportion of the whole soil seed bank. Because of the effect of wind erosion, seeds in deep soil could be gradually exposed to shallow soil layers and potentially contribute to population recruitment and vegetation restoration on active sand dunes. Copyright © 2015 John Wiley & Sons, Ltd.     

Seed Nitrogen Mobilization in Soybean: Effects of Seed Nitrogen Content and External Nitrogen Fertility

Soybean breeding programs have developed genetic lines with relatively low seed protein, which could negatively impact early seedling growth in low fertility conditions commonly encountered in the field. In these experiments, seed protein mobilization and its regulation in situ in soybean lines with different seed protein levels was investigated. The results showed that rates of nitrogen (N) release from cotyledons were much lower with decreasing levels of N in seed. Patterns of proteolysis of the storage proteins glycinin and β -conglycinin and their subunits were not different, but breakdown rates were slower. Seed N release rates increased somewhat when external N was supplied to roots of the developing seedlings, suggesting the involvement of source/sink controls. The effect appeared to be down-stream from proteolysis, as rates of protein breakdown were not altered. The results indicate that low seed protein levels will lead to reduced seedling fitness in low fertility soil conditions unless fertilizer N is applied.     

Weed seed bank affected by tillage intensity for barley in Alaska

The weed seed bank of a long-term tillage study in subarctic Alaska was studied at the end of 10 years of continuous spring barley (Hordeum vulgare L.). Tillage treatments were: no-till, disked once (spring), disked twice (spring and fall), and chisel plow (fall). Soil cores were obtained from each tillage treatment and seeds were manually separated from soil after washing through sieves. Tillage treatment had a significant effect on seed density of shepherds purse (Capsella bursa-pastoris (L.) Medic.), cinquefoil (Potentilla norvegica L.), foxtail barley (Hordeum jubatum L.), and on total seed density. Seed density was higher for these species and total seed density was greater under no-till than under other tillage treatments. Seed density was higher near the soil surface under no-till and chisel plow treatments than under disked treatments, which helps explain the greater difficulty of controlling weeds under reduced tillage.     

Cover crop and plant density in seed production of white clover (Trifolium repens L.)

Seed crops of white clover (Trifolium repens L.) are usually established with a cover crop. Provided sufficient light, white clover may compensate for low plant density by stoloniferous growth. Our objectives were (1) to compare spring barley or spring wheat used as cover crops for white clover and (2) to find the optimal seeding rate/row distance for white clover. Seven field trials were conducted in Southeast Norway from 2000 to 2003. Barley was seeded at 360 and 240 seeds m^?2 and wheat at 525 and 350 seeds m^?2. White clover was seeded perpendicularly to the cover crop at 400 seeds m^?2/13 cm row distance or 200 seeds m^?2/26 cm. Results showed that light penetration in spring and early summer was better in wheat than in barley. On average for seven trials, this resulted in 11% higher seed yield after establishment in wheat than in barley. The 33% reduction in cover crop seeding rate had no effect on white clover seed yield for any of the cover crops. Reducing the seeding rate/doubling the row distance of white clover had no effect on seed yield but resulted in slightly earlier maturation of the seed crop.