海口美舍河凤翔湿地公园植物配置与净化功能研究

海口美舍河凤翔湿地公园是改善海口市区水生态环境工程的重要组成部分。该研究调查了公园湿地植物的种类组成与空间布局,显示人工湿地共使用水湿生植物16科18属19种,其中湿生植物5科5属5种,挺水植物8科8属9种,浮水植物3科3属3种,沉水植物2科2属2种,人工湿地采取8级阶梯结构,自上而下随着水位渐深分别种植湿生植物、挺水植物、挺水—浮水植物、浮水—沉水植物、挺水—浮水—沉水植物,利用各类水湿生植物的净化能力去除污水中的N、P,实现湿地的净化功能。最后根据收集的资料,计算出美舍河凤翔湿地公园人工湿地每年吸收N的总量为3252kg,每年吸收P的总量为570kg,文章最后对其美学功能、生物多样性功能和科学管理进行了分析和讨论。     

北京园林五种乔木蒸腾模拟及其对环境因子的响应比较

通过对北京市园林常用5种乔木国槐（Sophora japonica）、银杏（Ginkgo biloba）、白蜡（Fraxinus chinensis）、杜仲（Eucommia ulmoides）、臭椿（Ailanthusahissima）等植物蒸腾作用与周围环境气象因子（温度、湿度、太阳有效辐射）及植株叶面积指数相关关系研究,利用Javis公式计算冠层气孔阻力,再采用PM公式计算冠层蒸腾速率、植株日蒸腾量,并分析不同乔木的冠层气孔导度对环境主要驱动因子响应规律。结果表明：五种被观测乔木中,国槐耗水量最大,白蜡耗水量最低,植株蒸腾量大小依次为国槐〉银杏〉杜仲〉臭椿〉白蜡（P〈0．01）。从植物叶片气孔导度及蒸腾量与环境驱动因子太阳辐射与水气压亏缺的相关关系来看,在保障土壤水分条件较好时,国槐长势好于其他4种乔木,其对水分的利用不够经济,在干旱的情况下不能有效节水。     

长沙市洋湖人工湿地冬季去污效果与植物效应

[目的]为了更好地研究人工湿地,进一步了解人工湿地的冬季去污效果,更科学的开展污水处理厂尾水的净化工作.[方法]对洋湖人工湿地2019年12月的水质和植物进行采样分析.[结果]1)洋湖人工湿地系统中植物生物量变化为一级人工湿地>二级人工湿地>三级人工湿地;人工湿地中植物茎叶和根部分的氮的比值均大于1,说明植物吸收的氮能...     

运行工况对垂直流人工湿地净化水体污染物影响

指出了人工湿地净化水体污染物的污水处理系统是生态可持续的净水模式,以垂直流人工湿地为研究对象,探讨了人工湿地运行工况(进水时间、间隔时间、运行周期、水力负荷、湿地结构出水口高度及湿地植物)对净化水体污染物的效果。结果表明:运行工况对COD污染物去除影响较小;随运行周期增加和间隔时间减小,TN的去除效率增加4.5%和13.59%;随水力负荷减小,垂直流人工湿地净化水体各项污染物能力都显著提升;人工湿地出水口由0m提高到1m,TN去除率提高超过50%;湿地植物对湿地系统净化水体氮素、磷素污染物去除率的提升贡献较小。垂直流人工湿地按最佳去除效果运行工况条件运行,TP、NH3-N和COD出水水质均达到地表水环境质量V类标准。     

人工湿地系统影响因素分析

指出了人工湿地系统对处理分散生活污水具有广阔的应用前景,其核心技术主要在于对植物种植、床体深度和填料的设计,归纳了湿地类型、植物种植、床体深度和填料对净化效果影响的研究概况,对目前取得较好净化效果的工程实例与试验研究进行了分析,以期为人工湿地系统的工程设计、技术研究及运行管理提供参考。     

低温环境人工湿地处理技术强化措施与应用

指出了人工湿地处理技术是通过植物吸收、微生物同化和基质吸附等协同过程高效去除污染物的综合生态系统,但在低温环境中湿地对污染物质的去除效果相对较差,导致其在低温地区的推广和应用受到限制。通过分析低温对湿地系统中生物和非生物结构的影响,思考了解决低温对湿地净化影响的具体强化措施,从内部改善优化(植物配置优化、生物强化和基质优化)和外部措施(保温和人工曝气)两大方面进行了介绍,并提出了对收割后的植物资源化利用、强化湿地基质、提高湿地大棚经济效益以及将外部措施与组合工艺配合等建议。以提高低温下湿地系统性能,为低温地区湿地系统的推广与应用提供技术参考。     

辽河中下游水生植物群落分布特征及与环境关系分析

结合辽宁省湿地调查,采用样方法调查了辽河中下游湿地水生植物,对植物组成、水体环境进行了相关性分析。结果表明:流域内现有水生植物44种,其中沉水植物8种、浮水植物12种、挺水植物24种。主要植物群落类型14个。群落间各环境因子中水体深度、总氮、总磷、溶解氧等变化显著,是决定该区域水生植物分布的主要因子。     

水生植物在人工湿地废水净化中的应用研究

水生植物作为人工湿地废水处理系统的一个重要组成部分,在废水净化过程中起着重要作用。对人工湿地生态工程中水生植物的作用,常用的植物种类及国内外对其选择的研究进行了综述。并在此基础上介绍了目前浙江大学生命科学学院农业生态与工程研究所利用水生植物净化养鸭场废水的研究状况。     

北京地区不同湿地植物对生活污水的净化效果研究

选择北京地区芦苇、东方香蒲、水芹、睡菜和蒿柳5种湿地植物,设计6种不同的植物配置方式,研究不同湿地植物单种及其配置对水中pH值、化学需氧量(COD)、总氮(TN)和总磷(TP)的净化效果。通过连续6个月的动态监测,结果表明:湿地植物对污染物有明显的净化效果,且9月份前随着温度的升高和植物的生长逐步提高,9月份后净化效果上升趋势趋于缓和或下降。单种湿地植物中,东方香蒲对pH值净化效果最好,睡菜对COD净化效果最好,芦苇对TN净化效果最好,蒿柳对TP净化效果最好,东方香蒲、蒿柳对上述污染物的综合净化效果最好;从湿地植物单种和植物配置对污染物的净化效果比较来看,植物配置对pH值、TN的净化效果高于单种,而对COD和TP的净化效果低于单种,芦苇和睡菜适合与其他植物配置使用,而东方香蒲、蒿柳和水芹单种使用对污染物的综合净化效果高于与其他植物配置的效果。     

自然式人工湿地的营造与作用

以常州市武进区武南污水处理厂湿地景观规划项目为依托,以景观生态学原理为基础结合自然湿地的营造手法以及传统人工湿地的技术支撑,充分利用项目所在地的各方面条件,对项目进行合理的规划与设计;并通过实践观测结果检验出此次规划设计的人工湿地中基质、植物等对水质净化有着显著的效果;同时证实运用自然造景手法设计的人工湿地与传统的人工湿地相比有更好的景观效果。       

Atmospheric and soil drought reduce nocturnal conductance in live oaks

Nocturnal and daytime whole-canopy transpiration rate (E) and conductance (g = E/VPD, where VPD is leaf to air vapor pressure difference) were assessed gravimetrically in drought-treated and well-watered 3-year-old saplings of live oak species (Quercus series Virentes Nixon) from the southeastern USA (Quercus virginiana Mill.) and Central America (Q. oleoides Cham. and Schlecter). Our objectives were to: (1) quantify nocturnal and daytime E and g in a controlled environment; (2) determine the impact of severe drought on nocturnal E and g; and (3) examine whether unavoidable water loss through the epidermis could account for nocturnal water loss. We calculated daytime E during peak daylight hours (between 0930 and 1330 h) and nocturnal E during complete darkness (between 2200 and 0500 h). In addition to reducing E and g during the daytime, drought-treated plants reduced nocturnal E and g on a whole-canopy basis by 62-64% and 59-61%, respectively, and on a leaf-level basis by 27-28% and 19-26%, respectively. In well-watered plants, nocturnal g declined with increasing VPD, providing evidence for stomatal regulation of nocturnal transpiration. In drought-treated plants, g was low and there was no relationship between nocturnal g and VPD, indicating that water loss could not be reduced further through stomatal regulation. Both daytime and nocturnal g declined curvilinearly with predawn water potential for all plants, but nocturnal g was unrelated to predawn water potentials below -1 MPa. The reductions in daytime and nocturnal E and g during drought were associated with decreases in whole-plant and leaf hydraulic conductances. Observed nocturnal g was within the same range as epidermal conductance for oak species determined in previous studies under a range of conditions. Nocturnal E rose from 6-8% of daytime E for well watered plants to 19-20% of daytime E for drought-treated plants. These results indicate that, during drought, saplings of live oak species reduce g to a minimum through stomatal closure, and experience unavoidable water loss through the epidermis.     

元谋干热河谷区9种造林树种的水分生理特性比较

１９９３～１９９８年对元谋干热河谷区的９个造林树种的水分生理特性进行了观测。经对各观测树种水分状况、保水能力、蒸腾速率的分析对比表明：多数相思类树种主要通过减少叶子蒸腾耗水以提高其抗旱能力,蒸腾强度小有利于这些树种渡过旱季。乡土树种坡柳和桉类树种（除大叶桉）旱季蒸腾作用比较强烈,但离体叶片失水速度不快,它们具有特殊的水分平衡机制和较强的水分吸收能力,以此增强对干热河谷环境的适应性。此项研究为正确选择元谋以至金沙江干热河谷地区的适宜造林树种,以及人工林的水分管理措施提供了理论依据。     

Daily transpiration rates of woody species on drying soil

Among annual plants, daily transpiration rates, expressed as a fraction of volumetric soil water content available for transpiration, show a common pattern in response to soil drying. Initially, as soil dries, there is little decrease in transpiration rate until water availability has fallen to about one third that at field capacity. With further soil drying, relative transpiration rate decreases in a more-or-less linear fashion until all available water has been used. Data previously obtained for perennial woody species have often been confounded by different methods for determining available soil water. In this study, we investigated the daily transpiration response to soil drying in five woody perennial species: Thuja plicata Donn ex D. Don, Acer rubrum L., Robinia pseudoacacia L., Hibiscus sp. and Ibex aquifolium L. Transpiration was unaffected by soil drying until the initial estimated transpirable soil water fraction had decreased to between 0.23 and 0.32 of that at field capacity. Beyond this point, transpiration rate declined linearly with available soil water fraction until reaching one fifth the rate observed in well-watered plants. With further soil drying, the relative transpiration rates remained between 10 and 20% of that observed in well-watered plants. Maintenance of transpiration at these rates with further soil drying was hypothesized to result from contributions to transpiration of water stored in plant tissues. After taking tissue water storage into account, it was estimated that transpiration was curtailed as the available soil water fraction fell to between 0.26 and 0.37 of that at field capacity, which is comparable to values reported for annual crop plants.     

桉树的抗旱性研究进展

在干旱和半干旱地区,为了成功地栽培桉树,许多学者从不同角度对桉树种群的抗旱性机理和它们对不同干旱环境的反应进行了研究和探讨。结果认为,桉树种群的遗传基因能适应于干旱的环境。生长在水分短缺条件下的植株,是通过各种途径保持组织水含量在细胞免受伤害的临界值以上而达到其适应。一般来说,具有旱生植物特征的桉树种群对干旱的适应能力较强,它们能够生存在较干旱的环境条件下,但不可能从湿润的气候环境中取得生长优势。     

Water economy of Neotropical savanna trees: six paradigms revisited

Biologists have long been puzzled by the striking morphological and anatomical characteristics of Neotropical savanna trees which have large scleromorphic leaves, allocate more than half of their total biomass to belowground structures and produce new leaves during the peak of the dry season. Based on results of ongoing interdisciplinary projects in the savannas of central Brazil (cerrado), we reassessed the validity of six paradigms to account for the water economy of savanna vegetation. (1) All savanna woody species are similar in their ability to take up water from deep soil layers where its availability is relatively constant throughout the year. (2) There is no substantial competition between grasses and trees for water resources during the dry season because grasses exclusively explore upper soil layers, whereas trees access water in deeper soil layers. (3) Tree species have access to abundant groundwater, their stomatal control is weak and they tend to transpire freely. (4) Savanna trees experience increased water deficits during the dry season despite their access to deep soil water. (5) Stomatal conductance of savanna species is low at night to prevent nocturnal transpiration, particularly during the dry season. (6) Savanna tree species can be classified into functional groups according to leaf phenology. We evaluated each paradigm and found differences in the patterns of water uptake between deciduous and evergreen tree species, as well as among evergreen tree species, that have implications for regulation of tree water balance. The absence of resource interactions between herbaceous and woody plants is refuted by our observation that herbaceous plants use water from deep soil layers that is released by deep-rooted trees into the upper soil layer. We obtained evidence of strong stomatal control of transpiration and show that most species exhibit homeostasis in maximum water deficit, with midday water potentials being almost identical in the wet and dry seasons. Although stomatal control is strong during the day, nocturnal transpiration is high during the dry season. Our comparative studies showed that the grouping of species into functional categories is somewhat arbitrary and that ranking species along continuous functional axes better represents the ecological complexity of adaptations of cerrado woody species to their seasonal environment.     

Processes preventing nocturnal equilibration between leaf and soil water potential in tropical savanna woody species

The impact of nocturnal water loss and recharge of stem water storage on predawn disequilibrium between leaf (psiL) and soil (psiS) water potentials was studied in three dominant tropical savanna woody species in central Brazil (Cerrado). Sap flow continued throughout the night during the dry season and contributed from 13 to 28% of total daily transpiration. During the dry season, psiL was substantially less negative in covered transpiring leaves, throughout the day and night, than in exposed leaves. Before dawn, differences in psiL between covered and exposed leaves were about 0.4 MPa. When relationships between sap flow and psiL of exposed leaves were extrapolated to zero flow, the resulting values of psiL (a proxy of weighted mean soil water potential) in two of the species were similar to predawn values of covered leaves. Consistent with substantial nocturnal sap flow, stomatal conductance (gs) never dropped below 40 mmol m(-2) s(-1) at night, and in some cases, rose to as much as 100 mmol m(-2) s(-1) before the end of the dark period. Nocturnal gs decreased linearly with increasing air saturation deficit (D), but there were species-specific differences in the slopes of the relationships between nocturnal gs and D. Withdrawal and recharge of water from stem storage compartments were assessed by monitoring diel fluctuations of stem diameter with electronic dendrometers. Stem water storage compartments tended to recharge faster when nocturnal transpiration was reduced by covering the entire plant. Water potential of covered leaves did not stabilize in any of the plants before the end of the dark period, suggesting that, even in covered plants, water storage tissues were not fully rehydrated by dawn. Patterns of sap flow and expansion and contraction of stems reflected the dynamics of water movement during utilization and recharge of stem water storage tissues. This study showed that nighttime transpiration and recharge of internal water storage contribute to predawn disequilibrium in water potential between leaves and soil in neotropical savanna woody plants.     

Response of five temperate deciduous tree species to water stress

Gas exchange, tissue water relations, and leaf/root dry weight ratios were compared among young, container-grown plants of five temperate-zone, deciduous tree species (Acer negundo L., Betula papyrifera Marsh, Malus baccata Borkh, Robinia pseudoacacia L., and Ulmus parvifolia Jacq.) under well-watered and water-stressed conditions. There was a small decrease (mean reduction of 0.22 MPa across species) in the water potential at which turgor was lost (Psi(tlp)) in response to water stress. The Psi(tlp) for water-stressed plants was -1.18, -1.34, -1.61, -1.70, and -2.12 MPa for B. papyrifera, A. negundo, U. parvifolia, R. pseudoacacia, and M. baccata, respectively. Variation in Psi(tlp) resulted primarily from differences in tissue osmotic potential and not tissue elasticity. Rates of net photosynthesis declined in response to water stress. However, despite differences in Psi(tlp), there were no differences in net photosynthesis among water-stressed plants under the conditions of water stress imposed. In A. negundo and M. baccata, water use efficiency (net photosynthesis/transpiration) increased significantly in response to water stress. Comparisons among water-stressed plants showed that water use efficiency for M. baccata was greater than for B. papyrifera or U. parvifolia. There were no significant differences in water use efficiency among B. papyrifera, U. parvifolia, A. negundo, and R. pseudoacacia. Under water-stressed conditions, leaf/root dry weight ratios (an index of transpiration to absorptive capacity) ranged from 0.77 in R. pseudoacacia to 1.05 in B. papyrifera.     

Influence of soil water on the physiological and morphological components of plant water balance in Populus trichocarpa, Populus deltoides and their F(1) hybrids

Patterns of leaf growth, transpiration and whole-plant water balance in Populus trichocarpa, P. deltoides and their F(1) hybrids were studied during a soil drying cycle. Plant responses were analyzed during three distinct stages of dehydration. In stage I, the transpiration rate of drought-stressed plants remained constant and equal to that of well-watered plants even though soil water content declined by more than 40%. Stage II began as soil and plant water deficits induced stomatal closure. When soil water was expressed as a fraction of transpirable soil water, the transition from stage I to stage II occurred at soil water fractions of 0.35, 0.45 and 0.60 for P. trichocarpa, P. deltoides and their F(1) hybrids, respectively. Reductions in leaf growth coincided with the shift from stage I to stage II. As soil water declined further, decreases in relative transpiration and whole-plant leaf area were significantly greater in parental species than in F(1) hybrids. Inherent feedbacks controlling stomatal water loss and the maintenance and growth of leaf tissue appeared to differ between F(1) and parental genotypes in a pattern characteristic of an overdominant mode of inheritance.Stage III began once the ability of stomata to compensate for water loss had been exhausted. Substantial differences were found in plant survival during stage III, with F(1) hybrids surviving longer than parental species. Survival was more strongly correlated with the hydraulic conductivity of xylem tissues than with the dehydration tolerance of leaf tissues. Collectively, these responses suggest that F(1) hybrids were more drought resistant than either parental species and highlight the importance of whole-plant studies of functional relationships between plant growth, water balance and hydraulic conductivity.     

Transpiration modulates phosphorus acquisition in tropical tree seedlings

Several experiments were conducted with tropical tree and liana seedlings in which transpiration ratio and leaf phosphorus to carbon ratio (P:C) were measured. Transpiration ratio was expressed as kg H(2)O transpired g(-1) C incorporated into plant biomass, and leaf P:C as mg P g(-1) C. Leaf P:C was positively correlated with transpiration ratio across 19 species for plants grown under similar conditions (R(2)?=?0.35, P?相似文献   

Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes

We investigated tree water relations in a lower tropical montane rain forest at 1950-1975 m a.s.l. in southern Ecuador. During two field campaigns, sap flow measurements (Granier-type) were carried out on 16 trees (14 species) differing in size and position within the forest stand. Stomatal conductance (g(s)) and leaf transpiration (E(l)) were measured on five canopy trees and 10 understory plants. Atmospheric coupling of stomatal transpiration was good (decoupling coefficient Omega = 0.25-0.43), but the response of g(s) and E(l) to the atmospheric environment appeared to be weak as a result of the offsetting effects of vapor pressure deficit (VPD) and photosynthetic photon flux (PPF) on g(s). In contrast, sap flow (F) followed these atmospheric parameters more precisely. Daily F depended chiefly on PPF sums, whereas on short time scales, VPD impeded transpiration when it exceeded a value of 1-1.2 kPa. This indicates an upper limit to transpiration in the investigated trees, even when soil water supply was not limiting. Mean g(s) was 165 mmol m(-2) s(-1) for the canopy trees and about 90 mmol m(-2) s(-1) for the understory species, but leaf-to-leaf as well as tree-to-tree variation was large. Considering whole-plant water use, variation in the daily course of F was more pronounced among trees differing in size and crown status than among species. Daily F increased sharply with stem diameter and tree height, and ranged between 80 and 120 kg day(-1) for dominant canopy trees, but was typically well below 10 kg day(-1) for intermediate and suppressed trees of the forest interior.