氮气对储烟害虫烟草甲的防治效果

为明确实验室及实仓条件下,氮气对储烟害虫烟草甲4种虫态(幼虫、蛹、成虫、卵)的防治效果,在实验室设置20、25、30℃三个温度,以95%和99%浓度的氮气处理4种虫态的烟草甲,分别在1、2、4、6、8、10、12、14 d后取出,记录试虫死亡情况;在烟仓自然条件下,以99%浓度的氮气处理密闭烟垛中的烟草甲,分别在第9天和第30天取出,记录试虫死亡情况。结果表明,实验室条件下,6个组合处理对各虫态烟草甲均有一定的致死作用,且致死效果随氮气浓度的升高、温度的升高和处理时间的延长而增强。同时,氮气处理对不同虫态烟草甲的防治效果差异显著,对卵和成虫的防治效果高于其他虫态。99%浓度氮气在20、25、30℃条件下处理烟草甲卵4 d,99%浓度氮气在30℃条件下处理烟草甲成虫4 d,校正死亡率即可达100%;实仓条件下,99%浓度氮气处理密闭烟垛9 d,对烟草甲幼虫、蛹、成虫的校正死亡率可达100%。因此,20~30℃条件下,运用氮气杀虫技术可有效防治烟仓中各虫态烟草甲,温度越高、氮气浓度越大效果越好。

荒漠河岸林典型植被胡杨叶片气孔导度模拟研究

胡杨是西北内陆干旱区生态系统的重要组成部分,气孔在维持胡杨正常的生理活动和其生态系统功能的发挥有着非常重要的作用。本文以2019年7—8月份额济纳荒漠河岸胡杨林叶片气孔导度为研究对象,结合胡杨生理指标以及环境因子实测数据,基于Jarvis模型、BWB模型和Bp神经网络模型3种模型,分别对胡杨叶片的气孔导度值模拟,并将模拟结果与实测结果进行比较,确定胡杨气孔导度的最适模型。结果表明,使用BWB模型模拟的气孔导度,其RMSE、RE和MAE值分别为0.071、0.453和0.058,这些相关数值均小于其他2种模型,且其决定系数R^(2)值为0.636,在3种模型中属于最大值,可见使用BWB模型的模拟效果最好;使用Bp神经网络模型模拟的效果次之,其RMSE、RE、MAE和R^(2)值依次为0.111、0.888、0.090和0.318,决定系数值处于居中位置;相比而言,使用Jarvis模型模拟的效果相对较差,其RMSE、RE和MAE值分别为0.838、4.958和0.788,这些数值均大于其他2个模型,且其决定系数R^(2)值为0.261,在3个模型模拟中最小。因此,对荒漠河岸林典型植被胡杨叶片气孔导度的模拟研究表明,BWB模型的模拟精度较高,由其模拟的叶片气孔导度值更接近基于Li-COR 6400便携式光合作用系统测定的真实值。

垄距和天气对玉米灌浆期开顶式气室(OTCs)增温效果的影响

气候变暖对作物生产系统影响显著,利用OTCs增温装置模拟农作物对气候变暖的响应是气候变化和农业生态领域的研究热点。作物生产系统在不同种植垄距下存在一定的水热交换差异,探明OTCs在不同垄距下的增温效果,尤其是在不同天气状况下的增温效果对分析作物生产系统响应气候变暖具有重要意义。本文在玉米灌浆期利用OTCs在黑龙江省海伦市野外田间开展了相同种植密度下垄距为55 cm、60 cm、65 cm和70 cm的模拟增温试验,利用Savitzky-Golay法和积分法定量分析了不同垄距,尤其是不同天气状况下,玉米OTCs冠层内外日温度变化特征和OTCs的增温幅度、增温时长和增温强度。研究发现,该装置能够使各垄距玉米冠层温度升高,65 cm垄距的增温时长最长,增温强度最大,升温最为明显。就增温幅度而言,55 cm垄距最大,65 cm垄距次之。不同天气状况下,晴天的增温幅度和增温强度最大,多云次之,雨天最小;但是,雨天天气下的增温时长最长。总之,不同垄距和天气状况显著影响OTCs装置的增温效果,垄距65 cm的增温效果最优,且晴天和多云天气下增温效果优于雨天。

Effects of Forest Type and Urbanization on Carbon Storage of Urban Forests in Changchun, Northeast China

Rapid urbanization has led to dramatic changes in urban forest structures and functions, and consequently affects carbon(C) storage in cities. In this study, field surveys were combined with high resolution images to investigate the variability of C storage of urban forests in Changchun, Northeast China. The main objectives of this study were to quantify the C storage of urban forests in Changchun City, Northeast China and understand the effects of forest type and urbanization on C storage of urban forests. The results showed that the mean C density and the total C storage of urban forests in Changchun were 4.41 kg/m2 and 4.74 × 108 kg, respectively. There were significant differences in C density among urban forest types. Landscape and relaxation forest(LF) had the highest C density with 5.41 kg/m2, while production and management forest(PF) had the lowest C density with 1.46 kg/m2. These differences demonstrate that urban forest type is an important factor needed to be considered when the C storage is accurately estimated. Further findings revealed significant differences in different gradients of urbanization, and the mean C density decreased from the first ring(6.99 kg/m2) to the fourth ring(2.87 kg/m2). The total C storage increased from the first ring to the third ring. These results indicate that C storage by urban forests will be significantly changed during the process of urbanization. The results can provide insights for decision-makers and urban planners to better understand the effects of forest type and urbanization on C storage of urban forests in Changchun, and make better management plans for urban forests.

Effects of Urbanization,Soil Property and Vegetation Configuration on Soil Infiltration of Urban Forest in Changchun,Northeast China

Urban forest soil infiltration, affected by various factors, is closely related with surface runoff. This paper studied the effect of urban forest types, vegetation configuration and soil properties on soil infiltration. In our study, 191 typical plots were sampled in Changchun City, China to investigate the soil infiltration characteristics of urban forest and its influencing factors. Our results showed that the steady infiltration rates of urban forest soil were highly variable. High variations in the final infiltration rates were observed for different vegetation patterns and compaction degrees. Trees with shrubs and grasses had the highest infiltration rate and trees with bare land had the lowest infiltration rate. In addition, our results showed that the soil infiltration rate decreased with an increase in the bulk density and with a reduction in the soil organic matter content and non-capillary porosity. The soil infiltration rate also had significantly positive relationships with the total porosity and saturated soil water content. Urban soil compaction contributed to low soil infiltration rates. To increase the infiltration rate and water storage volume of urban forest soil, proper techniques to minimize and mitigate soil compaction should be used. These findings can provide useful information for urban planners about how to maximize the water volume of urban forest soil and decrease urban instantaneous flooding.

流速对CO_(2)/O_(2)环境中L485钢腐蚀行为的影响

为研究CO_(2)/O_(2)共存环境中流速对L485钢腐蚀行为的影响,在高温高压动态反应釜中进行模拟腐蚀试验,测试L485钢的均匀腐蚀速率,通过扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等方法观测腐蚀产物的微观形貌和成分。结果表明:CO_(2)/O_(2)共存体系中,随着流速的增大L485钢的均匀腐蚀速率逐渐增大,且表面呈现由局部腐蚀向均匀腐蚀转变的特点;CO_(2)/O_(2)共存体系中L485钢的腐蚀产物为Fe2O3、FeOOH、Fe(OH)3、Fe3O4、FeCO3。

近10年太原市不同土地类型生态足迹与生态承载力研究

为探究资源型城市可持续发展的趋势,以太原市为例,系统计算了该市2011—2020年生态足迹和生态承载力状况。结果表明:太原市人均生态足迹呈现先下降后上升的趋势,平均为7.9892hm^(2)/人,具体消费表现为木材、用电量以及煤炭的消耗增加。人均生态承载力平均为0.2761hm^(2)/人,整体呈现先下降后增加的趋势,耕地、林地和建筑用地生态承载力所占的比例较大。太原市环境表现生态赤字,近10年平均为7.6754hm^(2)/人,化石能源消耗量过大是首要原因。

胡杨(Populus euphratica)对盐胁迫和干旱胁迫的生理响应特征

采用盆栽两年生幼苗,研究胡杨(Populus euphratica)在盐胁迫(NaCl浓度0、100、200、300、400 mmol·L^(-1))和干旱胁迫(干旱0、7、14、21、28 d)条件下的生理响应过程及其响应差异。结果表明:在抗氧化酶系统方面,随着盐胁迫和干旱胁迫程度的增加,保护酶超氧化物歧化酶、过氧化物酶和过氧化氢酶活性均呈现先增加后减小的趋势,不同保护酶的活性应对干旱胁迫和盐胁迫的反应速度和持续时间不同,胡杨通过将多种保护酶进行综合调节以形成整个抗氧化酶系统的防御功能。在渗透调节系统方面,随着盐胁迫和干旱胁迫程度的增加,可溶性糖含量持续增加,其积累对于不同程度的盐胁迫和干旱胁迫的反应速度和持续时间不同,胡杨通过持续性积累有机物质维持渗透平衡以形成渗透调节系统的长效防护功能。在细胞膜系统方面,随着盐胁迫程度的增加,丙二醛含量先减少后缓慢增加,基本维持在较低的水平,而随着干旱胁迫程度的增加,丙二醛含量持续增加,胡杨能够在盐胁迫和轻度干旱胁迫下通过细胞膜系统的适应性调节维持细胞膜结构功能的完整性以实现细胞膜系统的保护作用。在盐胁迫和干旱胁迫时,胡杨通过抗氧化酶系统、渗透调节系统和细胞膜系统进行适应性的调整,从而增强其耐盐性和抗旱性。进行胡杨盐胁迫和干旱胁迫生理响应研究对于黑河下游胡杨幼苗的培育和恢复具有重要意义。

不同土地利用类型盐碱土无机磷组分及其影响因素

为探究不同土地利用类型盐碱土无机磷组分特征及其影响因素,以华北地区典型盐碱地为供试土壤,分析辣椒地、轻度盐碱玉米地、重度盐碱玉米地、向日葵地、羊草地、虎尾草地、碱蓬草地和裸地共8种土地利用类型土壤无机磷组分的差异特征。结果表明:盐碱土壤无机磷组分中Ca_(10)-P所占比例最高,其他磷组分含量依次表现为Ca_(8)-P>Al-P>O-P>Fe-P>Ca_(2)-P。冗余分析和相关性分析结果表明,Ca_(2)-P和Ca_(8)-P与土壤pH、电导率、钠吸附比呈显著负相关(P<0.05),与速效磷、速效氮、速效钾呈显著正相关(P<0.05),土壤理化因子共解释了36.03%无机磷组分特征。因此,盐碱土中Ca_(2)-P、Ca_(8)-P是土壤磷有效性的关键组分,且主要受到pH、电导率和钠吸附比影响。根据8种土地利用类型土壤磷组分差异和理化性质,辣椒和向日葵可分别作为轻度和重度盐碱地改良利用的首选农作物,羊草可作为盐碱地生态修复的草地物种。此外,可以通过改善盐碱地土壤pH、电导率、钠吸附比、有机质等理化性质来提高土壤磷有效性。