Heavy Metal Toxicity Responses of Two Willow (Salix) Varieties Grown Hydroponically: Development of a Tolerance Screening Test

The E.U. funded BIORENEW project is investigating bioremediation of industrially degraded land using biomass fuel crops, including willow. One of its goals is to develop a rapid screening test to assess the metal tolerance of large numbers of willow varieties. This should reflect how a plant will respond to heavy metals under various field conditions and in the long term. A preliminary experiment tested two varieties of contrasting ability to thrive in metal-contaminated soils. Trees were exposed to a metal cocktail in three different strengths of background solution. An appropriate strength solution (1/4 strength Hoaglands) was identified for differentiating variety performance, based on its effect on the biomass of plant fractions relative to control fractions. This is a response to heavy metals which can be quantified rapidly and simply. The relative performance of the varieties was comparable to their performance in field studies. This test will be used to assess the tolerance of further varieties.     

甲基叔丁基醚(MTBE)蒸腾流浓度因子(TSCF)的试验评估

甲基叔丁基醚(MTBE)是北美燃料市场最常用的汽油添加剂，由于在土壤中的不吸附性和极高的水溶性．MT-BE已成为一种蔓延性的地下水污染物．植物修复技术被认为是目前对MTBE污染治理最为有效的方法之一．蒸腾流浓度因子（TSCF)作为植物修复技术中十分重要的参数，其通常是用污染物的辛醇-水分配系数(Kow)直接评估的。由于不同植物其体内脂肪含量不同，所以如果仅用污染物的Kow值来计算其TSCF值，往往不能准确表达污染物在植物体内的传输行为．由于MTBE在植物体内不发生降解，植物挥发是MTBE植物修复技术中唯一的作用机理．本实验用一自行设计的植物反应器来测定MTBE在不同温度条件下的TSCF值．长出新根须和嫩叶的柳树(Salix alba)枝条在一容积500mL的植物反应器中生长9-12d(其中MTBE溶液500mL，浓度4．81-6．60mg／L)来观察柳树对MTBE的吸收。MTBE的去除率和柳树的蒸腾量之间的关系用来计算其TSCF值．在15℃，20℃和25℃条件下，MTBE的TSCF值分别为0.58,0.75和0.49．本实验结果表明，柳树对MTBE的吸收是一个被动的行为，并且MTBE在柳树体内随蒸腾流的传输也有一定的限度。图2表1参11。     

Metal concentrations in deciduous tree leaves from urban areas in Poland

Accumulation of metals in deciduous tree foliage fromurban areas in western-south Poland was monitored duringthe vegetation season of 2000 year. Concentrations of Al,Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Ti and Znwere measured in birch, willow, linden and maple leavesusing the ICP-AES method. Seasonal variations of metalconcentrations and their relations with sampling sitewere investigated. The most dynamic accumulation of Al,Cd, Cr, Ni and Pb was observed for examined species. Thehighest differences in element concentrations forinvestigated sites were found for Ba, Cd, Mn and Ni.Interelement correlations were investigated. In allfoliar samples synergistic relationships between Al–Crand Ca-Sr were found. Statistically significant negativecorrelations were observed only for Cd and Ti in birch leaves.     

Tamarix and Diorhabda Leaf Beetle Interactions: Implications for Tamarix Water Use and Riparian Habitat

Tamarix leaf beetles (Diorhabda carinulata) have been widely released on western United States rivers to control introduced shrubs in the genus Tamarix, with the goals of saving water through removal of an assumed high water‐use plant, and of improving habitat value by removing a competitor of native riparian trees. We review recent studies addressing three questions: (1) to what extent are Tamarix weakened or killed by recurrent cycles of defoliation; (2) can significant water salvage be expected from defoliation; and (3) what are the effects of defoliation on riparian ecology, particularly on avian habit? Defoliation has been patchy at many sites, and shrubs at some sites recover each year even after multiple years of defoliation. Tamarix evapotranspiration (ET) is much lower than originally assumed in estimates of potential water savings, and are the same or lower than possible replacement plants. There is concern that the endangered southwestern willow flycatcher (Empidonax trailli extimus) will be negatively affected by defoliation because the birds build nests early in the season when Tamarix is still green, but are still on their nests during the period of summer defoliation. Affected river systems will require continued monitoring and development of adaptive management practices to maintain or enhance riparian habitat values. Multiplatform remote sensing methods are playing an essential role in monitoring defoliation and rates of ET on affected river systems.     

柳树乙醇提取物体外抗氧化活性

通过Fenton反应产生.OH,邻苯三酚自氧化产生O2.-模型,研究了柳树乙醇提取物体外清除自由基的作用。结果显示,柳茎和柳叶乙醇提取物在3.125—50 mg/ml浓度范围内具有清除O2.-的作用。随着浓度升高,其清除作用增大。在浓度达到50mg/ml时,柳茎提取物的清除率为75.62%,柳叶提取物的清除率为88.53%;柳茎乙醇提取物在3.125—25 mg/ml浓度范围内,清除.OH的能力随着其浓度的增加而逐渐增强。当浓度为25mg/ml时,其清除率为60.63%;柳叶提取物在浓度3.125—25mg/ml内清除.OH的作用不明显。当浓度达到50mg/ml时,对羟基自由基的清除率为60.63%。     

Combining Structured Decision Making and Value‐of‐Information Analyses to Identify Robust Management Strategies

Abstract: Structured decision making and value‐of‐information analyses can be used to identify robust management strategies even when uncertainty about the response of the system to management is high. We used these methods in a case study of management of the non‐native invasive species gray sallow willow (Salix cinerea) in alpine Australia. Establishment of this species is facilitated by wildfire. Managers are charged with developing a management strategy despite extensive uncertainty regarding the frequency of fires, the willow's demography, and the effectiveness of management actions. We worked with managers in Victoria to conduct a formal decision analysis. We used a dynamic model to identify the best management strategy for a range of budgets. We evaluated the robustness of the strategies to uncertainty with value‐of‐information analyses. Results of the value‐of‐information analysis indicated that reducing uncertainty would not change which management strategy was identified as the best unless budgets increased substantially. This outcome suggests there would be little value in implementing adaptive management for the problem we analyzed. The value‐of‐information analyses also highlighted that the main driver of gray sallow willow invasion (i.e., fire frequency) is not necessarily the same factor that is most important for decision making (i.e., willow seed dispersal distance). Value of‐information analyses enables managers to better target monitoring and research efforts toward factors critical to making the decision and to assess the need for adaptive management.     

Future distribution modelling: A stitch in time is not enough

The last two decades have seen an increasing number of studies assessing the impact of climate change upon biodiversity. A central assumption underpinning research into the potential future habitat of terrestrial biota is that species are presently in equilibrium with their environments and that quantitative climate models adequately represent the distribution of species. Recently, many alarming predictions have emerged concerning the extinction and redistribution of species. Here, we show that even large-scale models of the climatic niche dimensions of species are temporally variable. Distributional models were developed for Salix (willow) species occurring in the province of Ontario, Canada, using three historical climate data sets. Although historical data very accurately represented the distributions of willows, the inherent variability within the models of species based on different periods greatly influenced the direction and magnitude of projected distributional change. We expose a fundamental uncertainty with respect to predicting the responses of species to climate change.     

苏柳172和垂柳对Pb的吸收动力学特性及有机酸的影响

采用溶液培养的方法研究了苏柳172（Salix jiangsuensis CL‘J172’）和垂柳（Salix babylonica Linn）的Pb吸收动力学、Pb在根区的分布以及低分子量有机酸对Pb吸收的影响.结果表明,在溶液Pb浓度为0.25—100μmo.lL-1时,两种柳树对Pb的吸收动力学都呈非饱和曲线,积...     

Restoration of riparian forest using irrigation,artificial disturbance,and natural seedfall

In interior western North America, many riparian forests dominated by cottonwood and willow are failing to reproduce downstream of dams. We tested the hypothesis that establishment is now prevented by absence of the bare, moist substrate formerly provided by floods and channel movement. Along Boulder Creek, a dammed stream in the Colorado plains, we tested the effects of disturbance (sod removal), irrigation, and addition of seed on the establishment of seedings of plains cottonwood (Populus deltoides subsp.monilifera) and peachleaf willow (Salix amygdaloides). In unirrigated, undisturbed plots, mean cottonwood density was 0.03 seedlings/m². Irrigation or disturbance alone produced mean cottonwood densities of 0.39 and 0.75 seedlings/m². Plots that were both irrigated and disturbed produced a mean cottonwood density of 10.3 seedlings/m². The effects of irrigation and disturbance on cottonwood establishment were significant (P<0.005); added seed had no significant effect (P=0.78). The few cottonwood seedlings in unirrigated plots were in low positions susceptible to scour by future moderate flows. We conclude that cottonwood establishment along Boulder Creek is limited by the scarcity of bare, moist sites safe from future scour. Establishment of peachleaf willow was significantly affected only by disturbance; daily sprinkler irrigation did not provide sufficient moisture to increase survival of this species. Our results demonstrate the feasibility of restoring plains cottonwood forests using natural seedfall, even where only widely scattered adult trees are present. Because use of natural seedfall conserves the genetic makeup of the local population, this method may be preferable to the use of imported cuttings.