荒漠绿洲区芦苇种群构件生物量与地下水埋深关系

在野外调查的基础上 ,利用 Pearson关联分析法研究了河西荒漠绿洲区不同生境中芦苇种群构件生物量与地下水埋深的关系 ,结果表明 :地下水埋深对芦苇种群的影响明显 ,主要体现在 :在湿地和地下水埋深小于 0 .5 m的生境中 ,芦苇种群表现为高的种群密度、低的种群高度、低的地上生物量和高的地下生物量 ;在地下水埋深为 1 .5 m左右的生境中 ,芦苇种群地上生物量最高 ,生长最旺盛。随着地下水埋深的增加 ,垂直根茎生物量对芦苇种群地上生物量的影响加强 ,而水平根茎生物量对芦苇种群生物量的影响呈随机型 ,这可能是造成芦苇种群呈不连续、斑块状分布的主要原因。在地下水埋深 1 .5 m左右的生境中 ,芦苇的垂直根茎对种群生物量影响十分显著 ( P<0 .0 1 ) ;在地下水埋深 1 .5～ 4.0 m的生境中 ,影响显著 ( P<0 .0 5 ) ,但在地下水埋深 4m以上的生境中影响不显著 ,这表明在河西荒漠绿洲区 ,芦苇垂直根茎的最大水力提升高度 4m左右     

黄土丘陵区人工林地土壤肥力评价

就黄土丘陵区人工林地土壤肥力状况进行了综合评价。结果表明,全氮、碱解氮和有机质是黄土丘陵区人工林土壤主要的肥力指标,其含量能更好地反映土壤肥力状况。利用年限小于10年的土壤肥力处于很低的水平,利用年限在10～20年间的土壤肥力处于较低水平,利用年限在20年以上的土壤肥力接近中等水平。黄土丘陵区人工林土壤养分中除全磷和速效钾外,其它养分含量均偏低,该区人工林土壤肥力总体水平偏低。     

水分胁迫对2种生态型芦苇（Phragmites communis）的可溶性蛋白含量、SOD、POD、CAT活性的影响

研究利用2种抗旱性迥异的芦苇为材料,用PEG6000进行水分胁迫处理,结果表明,抗旱性强的沙丘芦苇（沙芦）的可溶性蛋白含量明显低于沼泽芦苇（水芦）,约为水芦的1／5。但是,在受到20％PEG胁迫时,沙芦的可溶性蛋白含量有所上升,水芦的则稍微下降,在30％PEG胁迫时,水芦的可溶性蛋白含量显著下降,而沙芦则先升后降。沙芦的3种自由基清除酶（SOD、POD、CAT）的活性显著高于水芦。受到水分胁迫后,2种芦苇的SOD、POD、CAT活性或升或降。但是,无论在20％还是30％PEG胁迫条件下,相对水芦而言,沙芦都保持较高的自由其清除酶活性,从而保证其较强的自由基清除能力,减轻自由基对植物细胞生物大分子如DNA、蛋白质、脂肪酸的伤害,维持细胞正常的生命活动,这是沙芦抗旱性强的基础。     

Disturbance, Herbivory, and Propagule Dispersal Control Dominance of an Invasive Grass

Despite the dramatic changes invasive plants cause to ecosystems and communities, factors that control dominance of invasive species after establishment in a community are poorly understood. Most active management relies on catastrophic disturbances of invasive-dominated communities to increase richness and diversity of plant communities. This study examines the importance of propagule dispersal and deer herbivory on continued dominance of Phalaris arundinacea after a non-catastrophic, short-term disturbance to monotypic stands of this invasive grass. The disturbance caused no change in P. arundinacea cover among treatments during any year of the study and, thus, simulates disturbance intensity more likely to be encountered in unmanaged settings. Despite the small disturbance, the combinations of disturbance + seeding and disturbance + seeding + deer exclusion caused greater species richness than controls even three years after disturbance. Increased invasion of P. arundinacea stands caused few effects on the dominant, as P. arundinacea biomass was unaffected after the first year. Selective herbivory by deer of species other than P. arundinacea increased the effects of disturbance and seeding, and aided in continued dominance of the grass. The tolerance of P. arundinacea for direct anthropogenic effects, including poor water quality and hydroperiod fluctuations, and indirect effects, such as increased herbivory by historically high deer populations, indicates the complexity of determining persistence of invasive species.     

Performances of constructed wetlands for municipal wastewater treatment in rural mountainous area

A global performance evaluation of an experimental Horizontal SubSurface Flow Constructed Wetlands (HSSF) was made after 6 years of functioning. This wetland is situated in French prealpine mountain, at 720 m elevation. The HSSF process treatment consists in a three-stage system dimensioned for 350 People Equivalent. Different helophytes were planted such as Typha latifolia, Phragmites australis and Scirpus maritimus. The mean hydraulic residence time for sewage was closed to 4–5 days, but in summer the mean pollutant residence time increases to 6 days due to an important evapotranspiration. There is no clogging of the gravel matrix and the hydraulic conductivity was very good and stabilized. Removal pollutant efficiency was determinate at each stages. There was a high removal of total suspended solids (TSS) all year around with an average of 95.6% (±3.6). More than 80% of removal occurred in the first stage. Physical processes (decantation, filtration) associated with biological oxidation were the principal factors of this removal. For COD and BOD₅, removal efficiency in the first stage were close to 60% on average and more than 90% at the outlet of the wetland. These results are similar to those observed with SSFW in many cases. Influence of temperature seems very weak because there were no significant seasonal variations of the process efficiency. Minimum effluent quality standards (30 mg l^–1 TSS; 120 mg l^–1 COD; 40 mg l^–1 BOD₅) were always respected. In cold periods, nutrients uptake was reduced but remained up to 60% in average. Mean bacterial removal efficiency was about two order of magnitude (99%) but can reach up to five order of magnitude in summer. These cyclic variations follow a sinusoidal variation around an annual mean. Pollutants removals were correlated to their respective loadings and no limits has been observed except for nitrogen. These results confirm that SSFW, an ecotechnology, should be considered as an alternative to conventional treatment methods (activated sludge, fixed biofilm) for small communities even in mountainous area.     

An in-situ mobile interstitial water and sediment sampler (MISS)

An inexpensive, easily constructed sampler for collecting interstitial water and sediment, seperately or combined is presented. The instrument has been developed for use in wetlands and shallow water as a tool for taxonomical and ecological investigations. Different to other samplers, our sampling depth is down to more than one meter at defined depths. Sampling showed highly reproducable sampling results for both, hydrophysical-chemical and biological analysis, which will be shown in the article.     

开垦对黄河三角洲湿地净生态系统CO2交换的影响

近年来, 由于对湿地的不合理利用, 自然湿地被大面积地垦殖为农田, 导致湿地生态系统碳循环的模式发生改变, 从而影响了湿地生态系统碳汇功能。该研究通过涡度相关法, 对山东省东营市黄河三角洲芦苇(Phragmites australis)湿地和开垦多年的棉花(Gossypium spp.)农田的净生态系统CO₂交换(NEE)进行了对比观测, 以探讨该地区典型生态系统NEE的变化规律及其影响因子, 揭示开垦对芦苇湿地NEE和碳汇功能的影响。结果表明: 在生长季, 湿地和农田生态系统NEE的日平均值各月均呈明显的“U”型变化曲线, 非生长季NEE的变幅很小。生长季湿地生态系统日最大净吸收值和释放值分别为16.04 g CO₂·m^-2·d^-1(8月17日)和14.95 g CO₂·m^-2·d^-1(8月9日); 农田生态系统日最大净吸收值和释放值分别为18.99 g CO₂·m^-2·d^-1 (8月22日)和12.23 g CO₂·m^-2·d^-1 (7月29日)。生长季白天两个生态系统NEE与光合有效辐射(PAR)之间呈直角双曲线关系; 非生长季NEE主要受土壤温度(T_s)的影响; 生态系统生长季夜间NEE受T_s和土壤含水量(SWC)的共同影响; 湿地和农田的生态系统呼吸熵(Q₁₀)分别为2.30和3.78。2011年生长季, 黄河三角洲湿地和农田生态系统均表现为CO₂的汇, 总净固碳量分别为780.95和647.35 g CO₂·m^-2, 开垦降低了湿地的碳吸收能力; 而在2011年非生长季, 黄河三角洲湿地和农田生态系统均表现为CO₂的源, CO₂总释放量分别为181.90和111.55 g CO₂·m^-2。全年湿地和农田生态系统总净固碳量分别为599.05和535.80 g CO₂·m^-2。     

Metal storage in reeds from an acid mine drainage contaminated field

Phragmites australis has been used to treat acid mine drainage (AMD)-contaminated soil. However, the mechanism about metal translocation in reeds was not widely reported. This study investigated metal (Fe, Al, and Mn) storage location in reeds grown in five different sampling sites of an AMD field. As expected, the more metals in soil, the more metals entered the belowground organs of plants. Reeds grown in soils with the highest levels of metals accumulated 0.16 ± 0.04 mg/g Mn, 16.29 ± 4.15 mg/g Fe, and 1.31 ± 0.22 mg/g Al in roots. Most of the iron was sequestered in the roots, while Al was transferred to the shoots. Histological staining found that most of the iron was sequestered in the exodermis, while Al extended the endodermis of roots. Al even entered the stele of roots grown in soil with higher Al levels. The epidermis, cortex, and central cylinder of rhizomes were the main tissues for Fe and Al storage. The more metals in rhizomes, the stronger intensity of the staining was observed around the vascular systems of rhizomes. No structural difference was observed among reeds collected from different sites. Further studies may be needed to enhance the transfer of metals in reeds and increase the phytoremediation efficiency.     

Impact of the arundo wasp,Tetramesa romana (Hymenoptera: Eurytomidae), on biomass of the invasive weed,Arundo donax (Poaceae: Arundinoideae), and on revegetation of riparian habitat along the Rio Grande in Texas

An invasive grass, Arundo donax, occupies thousands of hectares of arid riparian habitat along the Rio Grande in Texas and Mexico, and has negative impacts on national security, water resources, and riparian ecosystems. The shoot-tip-galling wasp Tetramesa romana was released in 2009 between Brownsville and Del Rio, Texas, and has dispersed over 800?km along the river channel. Plots along the river were surveyed for shoot counts of arundo and all other plant species in 2016 at seven sites in regions in which prior studies had documented a 22% decline in arundo biomass (estimated from live shoot length) from 2007 to 2014. Estimated live biomass declined a further 32% between 2014 and 2016. Native plants accounted for 86% of the 44 species encountered in plots. Individual plots averaged five plant species, and arundo was most abundant in only 9 of 21 plots. Arundo live biomass and shoot density were negatively associated with plant diversity, indicating that live arundo interferes with germination and/or survival of other plant species. The proportion of dead shoots in plots, proportion of wasp-galled shoots, and density of exit holes made by emerging adult wasps per metre live main shoot length were positively associated with plant diversity in a combined model. Regressions indicated that the effects of wasp damage measures on diversity were mediated through their effects on main shoot mortality. By reducing live arundo biomass, the arundo wasp is fostering recovery of native plant communities at riparian sites along the Rio Grande.     

安太堡矿区复垦地植被种间关系及土壤因子分析

为研究安太堡矿区植被复垦过程中不同植物群落类型的种间关系及影响群落稳定性的外部环境因子, 作者对矿区的植物群落和自然生境进行了野外调查。对森林、灌丛和草地3种群落分别在10 m×10 m、 4 m×4 m和1 m×1 m的尺度上, 采用校正的χ2检验、Spearman秩相关分析研究了不同群落类型中出现频率较高的物种之间的联结性, 同时应用灰色关联识别对影响群落稳定性的土壤因子进行了识别。结果表明: 草地群落中物种组成贫乏, 以旱生种为优势类群, 物种间既具有一定的联结性, 又具有相当独立的分布格局。灌丛群落主要种整体呈现正联结, 其组成成分仍以旱生或中旱生物种为主, 部分中生性物种的出现及其与优势种的正相关关系都在一定程度上指示了灌丛群落向正向演替方向进行。森林群落主要种也整体呈现正联结, 表明群落处于植被演替进程中一个相对稳定的过渡阶段。土壤因子与植物群落稳定性的关联顺序为: 有机质> N > P> K> Cu> Mn > pH > Zn>电导率。总的来看, 矿区现有森林群落配置方式是较灌丛群落和草地群落配置方式更适合于矿区特殊生境的群落类型, 而土壤因子中有机质在决定群落稳定性方面发挥重要作用。此研究结果对制定该矿区植被恢复计划具有参考价值。