The cortex (i.e., absorptive tissue) and stele (transportive vascular tissue) are fundamental to the function of plant roots. Unraveling how these anatomical structures are assembled in absorptive roots is essential for our understanding of plant ecology, physiology, and plant responses to global environmental changes. In this review, we first compile a large data set on anatomical traits in absorptive roots, including cortex thickness and stele radius, across 698 observations and 512 species. Using this data set, we reveal a common root allometry in absorptive root structures, i.e., cortex thickness increases much faster than stele radius with increasing root diameter (hereafter, root allometry). Root allometry is further validated within and across plant growth forms (woody, grass, and liana species), mycorrhiza types (arbuscular mycorrhiza, ectomycorrhiza, and orchid mycorrhizas), phylogenetic gradients (from ferns to Orchidaceae), and environmental change scenarios (e.g., elevation of atmospheric CO2 concentration and nitrogen fertilization). These findings indicate that root allometry is common in plants. Importantly, root allometry varies greatly across species. We then summarize recent research on the mechanisms of root allometry and potential issues regarding these mechanisms. We further discuss ecological and evolutionary implications of root allometry. Finally, we propose several important research directions that should be pursued regarding root allometry.

【Objective】 Nitrogen loss from terrestrial ecosystems is an environmental concern in many countries. It is affected by a multitude of biotic and abiotic factors. The purpose of this paper is to investigate the efficacy of soil amendment with straw in ameliorating nitrogen loss from watersheds in the Huaihe River basin. 【Method】 The experiment was conducted indoors using drab soil taken from the field. Artificial rainfall at intensity of 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mm/min were applied over the surface of soil amended with crop straw. Water and sediment runoffs from the soil surface, as well as nitrogen loss from both surface and subsurface runoff in each treatment were measured. 【Result】 Accumulative sediment runoff and nitrogen loss from the soil both increased with the rainfall intensity. The nitrogen concentration in the runoff changed more erratically in the first 20 minutes after the commencement of the rainfall, characterized by a rapid increase followed by a long tailing in all treatments. The average nitrogen concentration in the runoff measured from soil without straw amendment peaked when the rainfall intensity was 2.0 mm/min followed by 3.0 mm/min, while amending the soil with straw reduced this to 1.5 mm/min. The amount of nitrogen loss via sediment runoff accounted for 92.8% of the total loss from soil without straw amendment, and this reduced to 59.7% for soil amended by the straw. Soil amendment reduced surface runoff and sediment loss only when the rainfall intensity was low; when the rainfall intensity exceeded a threshold, soil amendment enhanced rather than reduced sediment runoff. Nitrogen concentration in the runoff was higher in soil without amendment than with amendment. 【Conclusion】 Amending soil with straw impacted surface runoff and loss of both sediment and nitrogen, but the effect varied with rainfall intensity. For soil without amendment, the nitrogen concentration in the runoff peaked when the rainfall intensity was 1.0 mm/min, and amending the soil with straw increased this to 1.5 mm/min.

为研究淮河流域农田非点源输出、区域农业非点源污染控制与管理,以河南淮河流域典型土壤(潮土)及其是否秸秆还田为对象,人工模拟0.5、1.0、1.5、2.0、2.5、3.0 mm·min-1降雨强度下的径流、泥沙和氮输出负荷.结果 表明:降雨强度越大,相同时间段内的累积径流量、累积泥沙量、氮输出量以及三者的产出速率均越大;径流中氮元素的浓度在降雨初期的20 min内变化较大,具初期冲刷效应,随后波动并趋于相对稳定或略有降低,其平均浓度在未掺混秸秆时以2.0 mm·min-1降雨强度时最大,其次为3.0 mm·min-1,掺混秸秆后以1.5 mm·min-1时最大;未掺混秸秆时氮元素泥沙输出量占总输出量的98.25％以上,但掺混秸秆后输出量有所降低(最低值为65.12％).秸秆还田后,分别可在<1.0 mm·min-1与<1.5 mm·min-1的低降雨强度下减少径流与泥沙流失量,高降雨强度下则增加泥沙流失量;径流氮元素浓度比未掺混秸秆的高,增加了氮元素的累积输出量.累积径流量与累积泥沙量间及两者分别与氮元素输出量之间均存在良好的幂函数与对数函数关系,相关系数均在0.900以上.研究表明,降雨强度、秸秆还田均对径流、泥沙、氮输出等产生影响,引起氮输出明显变化的降雨强度在未掺混秸秆时为1.0 mm·min-1,在掺混秸秆时为1.5 mm·min-1;减少农田非点源氮输出负荷的重要途径包括控制产流初期氮流失与泥沙流失.

环境影响评价课程是高等院校环境科学和环境工程专业本科生学习的核心课程,具有综合性、时效性和实践性强等特点.分析河南农业大学环境影响评价课程教学过程中存在的主要问题,通过课堂问题导入,精心布设教学过程,结合案例分析,编写环境影响评价文件与课程理论传授同步等新的思路,初步探讨课程教学改革措施.为其他高校环境影响评价课程教学理论知识的传授和培养专业性职业技术人才提供理论指导依据.

[目的]明确养殖蚯蚓对豫东黄泛沙质平原土壤肥力及107杨和中林46杨生长的影响.[方法]以豫东黄泛沙质平原林地养殖蚯蚓1 a和5 a的2处杨树人工林为研究对象,2处未养殖蚯蚓的杨树人工林为对照,于2017年8月中旬采集土样,测量杨树的胸径、树高、南北和东西冠幅,并计算杨树树冠投影面积;带回的土样均采用常规方法测定其土壤容重、含水率、pH值及有机质、全氮、全磷、全钾、有效磷和速效钾含量;选用7个土壤肥力因子,计算土壤肥力综合评价指标,分析杨树生长因子与土壤质量因子的相关性.[结果]养殖蚯蚓1 a的样地土壤含水率较对照区显著提高了63.15％(P<0.05),5 a的样地土壤容重、pH值分别较对照区显著降低了9.64％、1.58％(P<0.05),含水率、有机质含量分别较对照区显著提高了85.18％、197.48％(P<0.05);养殖蚯蚓1 a的样地土壤全磷较对照区低12.31％,养殖蚯蚓5 a的样地土壤全氮、全磷、全钾、有效磷、速效钾分别较对照提高187.88％、36.54％、1257.06％、232.62％、74.58％,差异均显著(P<0.05);养殖蚯蚓1 a的样地(D1)及其对照区(CK1)、养殖蚯蚓5 a的样地(D5)及其对照区(CK5)的土壤肥力综合指标分别为0.538、0.462、1和0;土壤容重、土壤有机质和速效钾含量与杨树胸径之间均存在极显著正相关(P<0.01);土壤容重、有效磷和速效钾含量与杨树树高间均存在显著正相关(P<0.05),其中土壤容重为极显著相关(P<0.01);土壤容重、土壤有机质、全氮、全磷、有效磷、速效钾含量与杨树树冠投影面积之间存在显著正相关(P<0.05),其中土壤容重同样为极显著相关(P<0.01).养殖蚯蚓1 a的样地杨树平均胸径、树冠投影面积较对照提高14.81％、31.28％,养殖蚯蚓5 a的样地杨树平均胸径、树高及树冠投影面积分别较对照提高17.14％、19.93％、32.94％,差异均显著(P<0.05).[结论]长期(5 a)较短期(1 a)的蚯蚓养殖更能显著提高土壤肥力;长期(5 a)的蚯蚓养殖均可显著提高对杨树生长因子有显著正相关的土壤肥力因子,可认为长期(5 a)蚯蚓养殖对杨树的生长有利.

为掌握三门峡市陕州区野生木本植物种质资源现状,通过实地线路踏查与样地调查相结合、面上调查与重点区域调查相结合的方法对该区4个镇、9个乡和2个林场的野生木本植物种质资源进行了调查分析.调查结果显示:陕州区野生木本植物共64科151属454种.其中,蔷薇科、豆科等15个科是优势科,含74属307种;悬钩子属、铁线莲属等7个属是优势属,共含103种.在区系地理分布上具有明显的过渡性,科以热带性质为主,属以温带性质为主.植物生长型丰富,以落叶树种为主.此外,该地区分布有银杏、红豆杉、厚朴、水曲柳等国家级重点、珍稀濒危和省级重点保护野生植物共22种.陕州区丰富的野生林木种质资源为该地种质资源的保护利用和良种引进等提供理论依据.

选择绿藻"水华"污染严重的郑州市东风渠金水段表层沉积物作为研究对象,采用消解法、电感耦合等离子体质谱法(ICP-MS)分析沉积物中Cd、Pb、Ni、Cu、Cr、Zn含量,采用原子荧光光谱法(AFS)分析Hg和As含量,运用Hakanson潜在生态风险指数法评价沉积物中8种重金属的生态风险.研究发现:1)沉积物中Hg、Cd、Pb、Zn含量超过土壤质量二级标准,超标倍数分别为1.71倍、0.85倍、2.94倍、0.09倍,Pb超标倍数最大.2)8种重金属平均潜在生态风险中,Hg为强生态风险,对潜在生态风险指数(ERI)的平均贡献率为56.1％,是主要的致险因子;Cd为中等生态风险,对ERI的平均贡献率为28.5％;其他重金属为轻微生态风险.结果表明:郑州市东风渠金水段表层沉积物中的重金属具有潜在的生态危害性.对污泥养分进行间接利用,避免产生二次污染,是改善生态环境、促进环境良性循环的良策.

In this study, a field-scale and pot experiment were performed to evaluate the remedial efficiency of Cd contaminated soil by tobacco and explore rhizosphere micro-characteristics under different cadmium levels, respectively. The results indicated that tobacco could remove 12.9 % of Cd from soil within a short growing period of 80 d. The pot experiment revealed that tobacco could tolerate soil Cd concentrations up to 5.8 mg kg(-1) and bioaccumulate 68.1 and 40.8 mg kg(-1) Cd in shoots and roots, respectively. The high Cd bioaccumulation in tobacco might be attributed to strong acidification in the rhizosphere soil and the increase in Cd bioavailability. Rhizobacteria did not appear to be involved in Cd mobilization. In contrast, tobacco tended to enrich sulfate-reducing bacteria (such as Desulfarculaceae) under high Cd treatment (5.8 mg kg(-1)) but enrich plant growth-promoting bacteria (such as Bacillus, Dyadobacter, Virgibacillus and Lysobacter) to improve growth under low Cd treatment (0.2 mg kg 1), suggesting that tobacco employed different microbes for responding to Cd stress. Our results demonstrate the advantages of using tobacco for bioremediating Cd contaminated soil and clarify the rhizosphere mechanisms underlying Cd mobilization and tolerance.

利用河南省国有焦作林场麻栎林1 hm2森林生态系统定位观测样地,设置加倍凋落物、去除凋落物、去除地表物并挖壕沟和对照(正常凋落物输入)等不同处理方式,连续2 a测定0～10 cm、10～20 cm土壤有效磷含量,计算其变化率、变化速率、环比增长率、同比增长率,分析暖温带森林近地表层土壤有效磷含量受凋落物输入改变的影响程度,为土壤有效磷动态的深入研究提供借鉴,为生态系统响应全球气候变化等研究提供基础.结果表明,土壤有效磷含量具有季节变化,春季与夏初较低、秋季与冬季较高;0～10 cm土层中土壤有效磷含量稍高于10～20 cm层次的,但差异不显著,其相关性可用幂函数表示.0～10 cm层次上,加倍凋落物处理提高了土壤有效磷含量,去除凋落物与去除地表物并挖壕沟处理降低了土壤有效磷含量,但不同处理间的差异性不显著,不同处理间土壤有效磷含量的变化率差异极显著;土壤有效磷含量的变化速率表现出减幅波动,而环比增长率与同比增长率在后期波动较大,但不同处理间均不具有显著性差异;凋落物输入的不同处理与季节变化对0～10 cm层次土壤有效磷含量有显著性影响,而对10～20 cm层次的影响不显著.表明,凋落物输入的不同处理主要影响到0～10 cm层次的土壤有效磷含量,对10～20 cm层次的影响较弱,且季节变化对土壤有效磷含量亦有较大影响.

为探讨植物根际促生菌用于强化烟草修复Cd污染土壤的可行性,采用盆栽试验,比较了4种根际促生菌剂对烟草吸收和积累Cd的影响.结果表明,4种植物根际促生菌(友益君菌剂、光合细菌菌剂、胶冻样芽孢杆菌菌剂、巨大芽孢杆菌菌剂)均提高了烟草地上部、地下部的Cd含量,并提高了烟草干质量,其中以光合细菌菌剂处理效果最优.相比对照(不加菌处理),施用光合细菌菌剂使烟草地上部、地下部Cd含量分别提高了36.4％、52.4％,使Cd总含量提高了191.2％,同时使烟草地上部、地下部的干质量均提高了100.0％.进一步分析发现,光合细菌菌剂处理提高了土壤有效Cd含量、总氮含量.光合细菌菌剂有望成为用于强化烟草修复Cd污染土壤的有效措施.

利用河南汝阳1 hm2森林生态系统定位观测样地,设置加倍凋落物(DL)、去除凋落物(NL)与对照(CK)3种处理,连续2 a测定0—10、10—20 cm层次土壤有效磷含量,旨在阐明暖温带栓皮栎林近地表层土壤有效磷受凋落物输入改变的影响程度,为人工林生态系统的经营管理及其对全球气候变化的响应对策提供基础.结果 显示:土壤有效磷质量分数年际变化不明显,其变化速率在处理1 a后波动幅度减小;环比增长率在0—10 cm土层变动幅度比10—20 cm土层的平缓,但各层次各处理的差异不显著;季节变化上,春秋季较低、冬季较高.0—10 cm土层的土壤有效磷含量稍高于10—20 cm土层,但差异不显著;0—10 cm土层上,加倍凋落物处理提高了土壤有效磷含量,去除凋落物处理降低了土壤有效磷含量,两种处理之间的土壤有效磷质量分数及其变化速率的差异显著,但与对照的差异均不显著;10—20 cm土层各处理间的差异不显著.研究表明,凋落物输入改变主要影响到0—10 cm土层的土壤有效磷含量,对10—20 cm土层的影响较弱.

[目的]了解北汝河流域非点源污染的时空分异,识别关键区域与重要时期,为防治非点源污染等提供理论依据.[方法]运用ArcGIS和ENVI软件与相关数据构建SWAT模型数据库,基于2001年与2014年土地利用数据,利用SWAT模型模拟了北汝河流域2001—2015年间非点源污染的时间动态与空间分异特征.[结果]SWAT模型适用于北汝河流域,校准期和验证期的R2和Ens均达到0.68以上,将该流域划分为70个子流域490个水文响应单元;以2001年与2014年土地利用数据模拟的泥沙、总氮、总磷负荷分别为29088.761、78870.342、1025.753 t/a与25315.033、70560.752、1207.841 t/a;2014年总磷负荷略有增加,其他负荷均有所下降.[结论]北汝河流域非点源污染负荷在汛期较为严重,以东部、中部的耕地与居民聚集区为关键控制区,且在东部有扩大趋势.

为更好地做好大学生入学教育工作,本文从两个具有不同特点的方面论述入学教育应该抓住的重点问题:一是从中学到大学的学习方式的转变,它需要尽快转变;二是道德情操的修养,它需要长期坚持.前者包括:认识到大学本科在人生中的重要性;处理好专业与知识拓展的关系;学习与思考的关系;培养创新意识;变被动学习为主动学习.后者包括:继续刻苦学习;明确读书目的;培养博爱精神;积极进取的品格.这样清晰的入学教育思路,可以让大学新生既尽快适应大学学习,又持之以恒地加强品德修养,达到教育大学生成才的目的.

为了解郑州市区主要河流春季浮游藻类的时空变化,分别于1999、2000、2015、2016年春季调查其种类组成、个体数量,并计算其多样性指数.结果表明:郑州市区主要河流春季浮游藻类组成基本上以绿藻、蓝藻与硅藻为优势,黄藻、金藻与甲藻偶尔出现,裸藻出现频率较大,但均不占优势;金水河自上游至下游沿程,浮游藻类的门类数、种类数与个体数量总体上均增加,多样性指数略下降.浮游藻类发生明显变化的时间大致在4月份,自1999年至2016年,种类数整体减少,2015年后个体数量明显下降,2016年数量显著下降.郑州市区主要河流基本上处于中营养化水平,水质属于轻污染,没有出现富营养化与贫营养化.研究结果可为北方城市河流的浮游藻类与水体富营养化长时间动态研究提供借鉴,以及为污染防治与水域的景观化利用提供依据.

选取太行山南麓麻栎林土壤为研究对象,设置对照(CK)、加倍凋落物(DL)、去除凋落物(NL)、去除凋落物和根系(NI)4种处理,观测1 a中0～10、10～20、20～30 cm土层有效氮含量和土壤容重变化,以探讨全球变化背景下凋落物和根系的输入变化对土壤有效氮的影响.结果表明,麻栎林土壤有效氮含量随土层加深而减小,各处理下均表现为0 ～ 10 cm＞ 10 ～ 20 cm＞ 20～30 cm,容重与有效氮含量均呈显著或极显著线性负相关.CK和DL处理下的土壤有效氮表现出明显的季节变化动态,秋冬季节较低,夏季较高;第一年秋季累积的凋落物主要在次年进行分解,试验开始5个月后(次年1月份)不同处理间的差异开始显现,与CK相比,DL提高了土壤有效氮含量,NL和NI降低了有效氮含量;同样去除凋落物的情况下,NI的土壤有效氮含量高于NL.不同处理间的差异在0～10、10～20 cm土层表现明显,20 ～ 30 cm土层容重受凋落物处理和时间变化影响不显著,该土层有效氮含量对不同处理的响应比较滞后.研究表明,该地区凋落物输入变化对土壤有效氮含量的影响大于地下根系造成的影响,容重等土壤物理性质发生同步变化.

In order to understand the eco-hydrology effect of near soil surface of railway green belt and its effect of maintaining the railway line slope stability,3 typical green belts along the Longhai line and the Beijing-Guangzhou line under the jurisdiction of Zhengzhou Railway Bureau were selected to deter-mine the water holding characteristics of the litters and the 0~30 cm layer soil. The result shows that:there is a good eco-hydrological effect between the vegetation litters and the soil,with the water holding capacity of near soil surface reaching 5.90% to 12.20% of the annual average precipitation, and 25.65% to 53.01% of the highest monthly average precipitation,which has a positive effect on green belt vegetation development and the line slope stability in northern region with less rainfall. The higher water infiltration rate of sandy soil is more important to guarantee the slope stability. It is believed that under the premise of ensuring the driving safety,selecting different plants for greening design and con-struction according to specific conditions, can ensure the stability of traffic line slope and bring good soil and water conservation benefits.

抽样调查了郑州市道路总长度的10％共128条道路的行道树,运用i-Tree模型对其生态效益进行了评估.结果显示,郑州市行道树共14科20属22种,80％树木胸径10～30 cm,90％树木健康水平为良好以上;总生态效益2476.77万元,其中截留雨水效益占55.03％,其他依次为碳储存、美学、CO2吸收、节能和空气质量改善;总生态效益中,悬铃木的贡献率69.43％,其次为国槐和白蜡;单株加权平均效益为2106元/株,悬铃木最高,其次为臭椿、国槐、白蜡和雪松;大叶女贞、银杏和枇杷无论是贡献率还是单株加权平均效益均最低.

为了解河南省生态旅游的自然禀赋潜力及其适宜性、适宜开发的空缺区域,利用GIS空间分析功能与叠图法,以植被覆盖度、生物丰度2个生物因子与高程、坡度2个地形因子作为自然禀赋潜力评价指标,将河南省生态旅游的自然禀赋潜力划分为适宜区、较适宜区、适度控制区和控制区4个等级区域,借鉴GAP分析思路进行了生态旅游空间的空缺分析,筛选出未来生态旅游开发的优先区域、次优先区域与控制区域,其中山区部分地区需要特别注意生态环境的脆弱性与难以修复性,防止开发破坏.研究结果可为河南省生态旅游规划、开发等提供理论依据.

Beside the Lanzhou-Lianyungang Railway and the Beijing-Guangzhou Railway under the jurisdiction of Zhengzhou Railway Bureau,some typical greenery plant of Ligustrum compactum,Platycladus orientalis and Photinia×fraseri are selected to determine its foliar dust detention and its vegetation zone of PM 10,PM2.5 and negative air ion concentration.The results show that;the railway greening vegetation has the positive effect to reduce the dust,PM10 and PM2.5 concentration and increase the negative air ions concentration.We find the evergreen species of Photinia ×fraseri and Ligustrum compactum have a higher foliar dust detention,while the Platycladus orientalis is smaller,but the PM10,PM2.5 and negative air ion concentration have no significant difference among most vegetation zone.It is believed that under the premise of ensuring the driving safety,selecting different plants for greening design and construction according to specific conditions can achieve the goal of environmental improvement.

Using Levins' niche breadth,Whittaker's niche similarity and Pianka's niche overlap,13 tree species in Stewartia shensiensis Chang community were surveyed and estimated.The results showed that:the niche breadth of the main dominant populations in Stewartia shensiensis Chang community was large.The niche breadth of Stewartia shensiensis Chang and co-dominant species Carpinus cordata Bl,Acer tegmentosum Maxim and Quercus aliena var.acuteserrata Maxim were 1.730 1,1.760 6,1.780 8 and 1.734 9,respectively.The Stewartia shensiensis Chang had a higher niche similarity with its co-dominant species.There is no significant correlation between niche breadth and niche similarity.The species with broad niche breadth had a larger niche overlap with other species due to its strong resource utilization ability,wide distribution and more competitive.Mmeanwhile,the species with narrow niche breadth could be difficult to coexistence with other populations due to its weak resource utilization ability,narrow distribution and weak competitive.The niche overlap was not necessarily high among populations with large niche breadth.According to niche overlap,the competition between Stewartia shensiensis Chang and understory species was greater than that between co-dominant story species.