Forecasting Alpine Vegetation Change Using Repeat Sampling and a Novel Modeling Approach

Global change affects alpine ecosystems by, among many effects, by altering plant distributions and community composition. However, forecasting alpine vegetation change is challenged by a scarcity of studies observing change in fixed plots spanning decadal-time scales. We present in this article a probabilistic modeling approach that forecasts vegetation change on Niwot Ridge, CO using plant abundance data collected from marked plots established in 1971 and resampled in 1991 and 2001. Assuming future change can be inferred from past change, we extrapolate change for 100 years from 1971 and correlate trends for each plant community with time series environmental data (1971–2001). Models predict a decreased extent of Snowbed vegetation and an increased extent of Shrub Tundra by 2071. Mean annual maximum temperature and nitrogen deposition were the primary a posteriori correlates of plant community change. This modeling effort is useful for generating hypotheses of future vegetation change that can be tested with future sampling efforts.     

Plant uptake and dissipation of PBDEs in the soils of electronic waste recycling sites

Plant uptake and dissipation of weathered PBDEs in the soils of e-waste recycling sites were investigated in a greenhouse study. Eighteen PBDE congeners (tri- through deca-) were detected in the plant tissues. The proportion of lower brominated PBDEs (mono- through hexa-) in plant roots was higher than that in the soils. A concentration gradient was observed of PBDEs in plants with the highest concentrations in the roots followed by the stems and lowest in the leaves. Reduction rates of the total PBDEs in the soils ranged from 13.3 to 21.7% after plant harvest and lower brominated PBDEs were associated with a higher tendency to dissipate than the higher brominated PBDEs. This study provides the first evidence for plant uptake of weathered PBDEs in the soils of e-waste recycling sites and planting contributes to the removal of PBDEs in e-waste contaminated soils.     

Ecosystem responses to reduced and oxidised nitrogen inputs in European terrestrial habitats

While it is well established that ecosystems display strong responses to elevated nitrogen deposition, the importance of the ratio between the dominant forms of deposited nitrogen (NH_x and NO_y) in determining ecosystem response is poorly understood. As large changes in the ratio of oxidised and reduced nitrogen inputs are occurring, this oversight requires attention. One reason for this knowledge gap is that plants experience a different NH_x:NO_y ratio in soil to that seen in atmospheric deposits because atmospheric inputs are modified by soil transformations, mediated by soil pH. Consequently species of neutral and alkaline habitats are less likely to encounter high NH₄⁺ concentrations than species from acid soils. We suggest that the response of vascular plant species to changing ratios of NH_x:NO_y deposits will be driven primarily by a combination of soil pH and nitrification rates. Testing this hypothesis requires a combination of experimental and survey work in a range of systems.     

Protection of plants from ambient ozone by applications of ethylenediurea (EDU): A meta-analytic review

A meta-analysis was conducted to quantitatively assess the effects of ethylenediurea (EDU) on ozone (O₃) injury, growth, physiology and productivity of plants grown in ambient air conditions. Results indicated that EDU significantly reduced O₃-caused visible injury by 76%, and increased photosynthetic rate by 8%, above-ground biomass by 7% and crop yield by 15% in comparison with non-EDU treated plants, suggesting that ozone reduces growth and yield under current ambient conditions. EDU significantly ameliorated the biomass and yield of crops and grasses, but had no significant effect on tree growth with an exception of stem diameter. EDU applied as a soil drench at a concentration of 200-400 mg/L has the highest positive effect on crops grown in the field. Long-term research on full-grown tree species is needed. In conclusion, EDU is a powerful tool for assessing effects of ambient [O₃] on vegetation.     

Trace element uptake in plants grown on fly ash amended soils

Four crop plants were grown in a greenhouse in soils amended with 0, 5, 10, and 20% by weight of coal combustion fly ash to evaluate potential trace element uptake by the vegetation. The leaves and stems from each plant were harvested and analyzed for As, Cd, Co, Cu, Mn, Mo, Pb, Se, Tl, and Zn content during early, middle, and late growth. The trace element data were statistically analyzed using Analysis of Variance (ANOVA) to determine whether the trace element uptake in the four crop plants differed significantly between the soil treatments, and to identify significant differences in trace element uptake through time. The results show that the amount of amended fly ash does not significantly influence the concentration of most trace elements in plant tissue, and that some concentrations actually decrease with time. Although this study did not find a significant increase in trace element uptake, care must be taken in a natural environment where plants may behave differently.     

氧瓶燃烧─离子色谱法测定植物叶片中硫

采用氧瓶燃烧处理植物样品，离子色谱法测定吸收液中ＳＯ_４~（２－）的方法来确定植物的含硫量，方法简便，分析周期短、重现性和回收率（９４．７％～１０９．２％）均令人满意。     

What enables coexistence in plant communities? Weak versus strong species traits and the role of local processes

Explaining the coexistence of species that basically depend on the same resources has been a brainteaser for generations of ecologists. Different mechanisms have been proposed to facilitate coexistence in plant communities, where space is an important resource. Using a stochastic cellular automaton simulation model we analyze - separately and in combination - the influence of different species traits and processes which alter local competition on the coexistence of plant species over a fixed time horizon. We show that different species traits operate on different time scales in competition. We therefore suggest the concept of weak versus strong traits according to short- or long-term exclusion of species differing in these traits. As a consequence, highly non-linear trade-offs between weak and strong traits can result in communities. Furthermore, we found that trade-offs based on physiological species traits such as plant lifetime, dispersal range and plant growth, did not support broad and long-term coexistence—further processes such as density-dependent mortality and light-dependent colonization were necessary. This suggests that coexistence in plant communities requires (stabilizing) local processes to support the (equalizing) trade-offs in species traits.     

Integrating gravity-driven ceramic membrane filtration with hydroponic system for nutrient recovery from primary municipal wastewater

In this study,a gravity-driven membrane(GDM)filtration system and hydroponic system(cultivating basil and lettuce)were combined for nutrient recovery from primary municipal wastewater.The GDM system was optimized by increasing the periodic air sparging flow rate from 1 to 2 L/min(～15 hr per 3-4 days),resulting in a～52％reduction of irreversible fouling.However,the total fouling was not alleviated,and the water productivity remained comparable.The GDM-filtrated water was then delivered to hydroponic systems,and the effects of hydroponic operation conditions on plant growth and heavy metal uptake were evaluated,with fertilizer-and tap water-based hydroponic systems and soil cultivation sys-tem(with tap water)for comparison.It was found that(i)the hydroponic system under batch mode facilitated to promote vegetable growth with higher nutrient uptake rates com-pared to that under flow-through feed mode;(ii)a shift in nutrient levels in the hydroponic system could impact plant growth(such as plant height and leaf length),especially in the early stages.Nevertheless,the plants cultivated with the GDM-treated water had compara-ble growth profiles to those with commercial fertilizer or in soils.Furthermore,the targeted hazard quotient levels of all heavy metals for the plants in the hydroponic system with the treated water were greatly lower than those with the commercial fertilizer.Especially,com-pared to the lettuce,the basil had a lower heavy metal uptake capability and displayed a negligible impact on long-term human health risk,when the treated water was employed for the hydroponic system.     

刍议我国直流冷却电厂冷却用水生态危害与减损

随着滨海核电厂装机容量的不断增加,温排水的海洋环境影响备受关注。针对《海水水质标准》（GB 3097－1997）中温升4 ℃以上的水体,于夏季大、小潮期间共获取红沿河核电厂周边海域共8个潮情的无人机热红外航测及现场同步实测数据,开展不同潮情下温排水温升强度空间分布的遥感识别,并分析潮汐、风场等驱动因素对温排水空间分布变化的影响。结果显示：（1）无人机航测SST经二次多项式校正后,平均绝对误差（MAE）为0.4 ℃,可用于温排水识别应用;（2）相同潮情下温排水空间分布特征相似,不同潮情下,涨憩和落憩潮情温升面积高于涨急和落急潮情,且离岸更近的高温升等级面积变化幅度较小,离岸较远的低温升等级面积变化幅度较大;（3）大潮落急潮情最有利于温排水扩散,而小潮涨憩潮情扩散效果最差;（4）潮汐较风场对温排水的空间分布有更大影响。