Eco-environmental water demands for the Baiyangdian Wetland

In recent years, the hydrological characters of Baiyangdian Wetland have changed greatly, which, in turn, influence the biotic component, the structure and function of the wetland ecosystem. In order to determine the demands for water resources of ecological wetland system, a method of ecological water level coefficient was suggested to calculate the water resources demands for wetland environment use. This research showed that the minimum coefficient is 0.94 and the optimal coefficient is more than 1.10. According to these two coefficients, the ecological water level and water quantity can be estimated. The results indicate that the amount of the minimal and optimal eco-environmental water requirements are 0.87 × 10⁸ and 2.78 × 10⁸ m³ in average monthly, respectively, with the maximum eco-environmental water requirement in summer and the minimum in winter. The annual change of eco-environment water demand is in according with the climate change and hydrological characters. The method of ecological water level emphasizes that wetland ecosystem adapts to the hydrological conditions, so it can be used in practice well. __________ Translated from Acta Scientiae Circumstantiae, 2005, 25(8): 1,119–1,126 [译自: 环境科学学报]     

人工湿地技术处理生活污水

本文评估了一级强化预处理＋人工湿地在处理生活污水方面的使用范围,提出当进水中氨氮达到35mg/L,通过一级强化预处理以及人工湿地的出水难以达到一级B标准;同时由于人工湿地大部分为厌氧环境,对硝态氮去除效果良好,本文提出在进水氨氮浓度较高的情况下,将硝化加入人工湿地的预处理,利用人工湿地的一部分硝化能力和良好的反硝化能力使出水达标排放。     

3种人工湿地填料对磷的动态吸附特征

以河沙、页岩、石灰石等3种重庆常见基质为人工湿地填料,探讨了磷负荷和有机负荷对基质动态除磷效果的影响。结果表明,在同等磷负荷和有机负荷情况下,3种填料的去除效果依次为石灰岩（河沙（页岩;有机负荷对各填料除磷有重要的影响,随着有机负荷的增加,填料除磷率均有不同程度的降低。有机负荷对石灰岩除磷的影响较大,对河沙除磷的影响相对较小。     

Optimizing model for land use/land cover retrieval from remote sensing imagery based on variable precision rough sets

The suitable spectral mode in remote sensing is often desirable to facilitate the inversion of ecological environment and landscape. This paper put forward an optimizing model based on variable precision rough sets (VPRS) for the land cover discrimination in wetland inventory. In the case study of Lake Baiyangdian which has important ecological functions to the northern China, this model is established successfully according to the domain-experts knowledge. The procedure is as follows. First step is data collection, including remote-sensing data (e.g., Landsat-5 TM bands), the digitized relief maps, and statistical yearbooks. Second, the remote sensing imagery (RSI) and relief maps are co-registered into the same resolution. Third, a condition set, including various attributes is derived from spectral bands, band math or ratio indices based on previous studies, at the same time, the decision set is derived from true land types after investigation and validation. Then, the remote sensing decision table (RSDT) is constructed by linking condition set with decision set according to the sequential pixels in RSI. Fourth, we create one forward greedy searching algorithm based on VPRS to handle this RSDT. After adjusting parameters such as β and knowledge granularity diameter (KGD), we obtain the stable optimized results. Comparative experiments and evaluation show that the discrimination or retrieval accuracy of VPRS model is satisfying (overall accuracy: 87.32% and KHAT: 0.84) and better than original data. Moreover, data dimension has been decreased dramatically (from 12 to 3) and key attributes found by the model may be useful for specific retrieval in wetland inventories.     

Ecological risk assessment of pesticide residues in Taihu Lake wetland, China

As a major ecosystem type, wetland provides invaluable ecological services. Environmental pollution, especially pesticides pollution should be paid more attention to keep wetlands healthy. Based on the risk quotient method, coupled with a probabilistic risk assessment model, this paper proposed a methodology suitable for ecological risk assessment of pesticide residues for wetland ecosystems. As an important industrializing and ecologically vulnerable area in China, the Taihu Lake wetland was chosen for the case study. The risks of eight pesticides in Taihu Lake wetland were assessed, as single substances and in mixtures. The assessment indicates that risks of the representative species are not significant. In general, the herbicide is found to be more toxic for algae, whereas insecticides pose more risks to zooplankton, insect and fish. For each pesticide in the wetland, the ecological risk it poses is acceptable. But the combined ecological risk posed by mixture can harm more than 10% of species of the wetland ecosystem, mainly dominated by dichlorvos, dimethoate and malathion contributions. These results imply that pesticide residues have been posing pressures on the ecosystem of the Taihu Lake wetland. It is recommended that proper countermeasures should be implemented to reduce the risks.     

南宁市相思湖湿地公园生态景观调查与分析

相思湖湿地公园是南宁市打造"中国水城"品牌的重要建设项目,既保护了湿地资源,也发挥了巨大的生态环境、经济及社会效益.就已完成景观绿化亮化提升工程的相思湖湿地公园展开相关调查,对其生态多样性进行分析及按照相关标准计算湿地景观特征指数,评价了其现状并提出保护对策.相思湖湿地公园具有丰富的动植物资源,从水域、林地、草地、沼泽、滩涂五种景观类型的数据可以看出:水域面积占到了52.74%,说明湿地功能显著;破碎度最大的是草地跟林地,分别达到了1.29和0.81,说明南宁市生态恢复工程和绿色提升工程效果明显.相思湖湿地公园是保护和利用当地湿地资源的有效措施.     

Uncertainty propagation in vegetation distribution models based on ensemble classifiers

Ensemble learning techniques are increasingly applied for species and vegetation distribution modelling, often resulting in more accurate predictions. At the same time, uncertainty assessment of distribution models is gaining attention. In this study, Random Forests, an ensemble learning technique, is selected for vegetation distribution modelling based on environmental variables. The impact of two important sources of uncertainty, that is the uncertainty on spatial interpolation of environmental variables and the uncertainty on species clustering into vegetation types, is quantified based on sequential Gaussian simulation and pseudo-randomization tests, respectively. An empirical assessment of the uncertainty propagation to the distribution modelling results indicated a gradual decrease in performance with increasing input uncertainty. The test set error ranged from 30.83% to 52.63% and from 30.83% to 83.62%, when the uncertainty ranges on spatial interpolation and on vegetation clustering, respectively, were fully covered. Shannon’s entropy, which is proposed as a measure for uncertainty of ensemble predictions, revealed a similar increasing trend in prediction uncertainty. The implications of these results in an empirical distribution modelling framework are further discussed with respect to monitoring setup, spatial interpolation and species clustering.     

On the sudden disappearance of Egeria densa from a Ramsar wetland site of Southern Chile: A climatic event trigger model

Contemporary shallow lakes theory proposes that these ecosystems may experience abrupt regime shifts due to small changes in controlling variables or triggers. So far, these triggers have been related mostly to nutrients as the immediate driver. During May 2004 the río Cruces wetland, a Ramsar site located in Southern Chile, underwent a major regime shift, from a clear water state, vastly dominated by the invasive macrophyte Egeria densa, to a turbid water state. In this article we show, through the analysis of long-term meteorological data that late fall 2004 was anomalous due to the presence of a high-pressure cell that persisted most of the month of May over Southern Chile. This climatic event caused an almost complete absence of precipitations and lower temperatures during this period, including several freezing nights. Eco-physiological experiments showed that 6 h exposure to desiccation kill the macrophyte. We developed a simple-biology dynamic model, under Stella Research 9.1, to show that the climatic anomaly of May 2004, plus the increased sedimentation of the wetland's floodplains, and the associated response of E. densa, explains its sudden disappearance from río Cruces wetland.     

湿地自然保护区与当地居民

本文介绍了我国湿地保护区与当地居民的关系对保护区管理情况的影响,并提出了一些合理化建议,其中强调了通过政策和经济杠杆让当地居民在保护环境中受益,保护区才可能持续发展。     

Monitoring waterbird abundance in wetlands: The importance of controlling results for variation in water depth

Wetland use by waterbirds is highly dependent on water depth, and depth requirements generally vary among species. Furthermore, water depth within wetlands often varies greatly over time due to unpredictable hydrological events, making comparisons of waterbird abundance among wetlands difficult as effects of habitat variables and water depth are confounded. Species-specific relationships between bird abundance and water depth necessarily are non-linear; thus, we developed a methodology to correct waterbird abundance for variation in water depth, based on the non-parametric regression of these two variables. Accordingly, we used the difference between observed and predicted abundances from non-parametric regression (analogous to parametric residuals) as an estimate of bird abundance at equivalent water depths. We scaled this difference to levels of observed and predicted abundances using the formula: ((observed − predicted abundance)/(observed + predicted abundance)) × 100. This estimate also corresponds to the observed:predicted abundance ratio, which allows easy interpretation of results. We illustrated this methodology using two hypothetical species that differed in water depth and wetland preferences. Comparisons of wetlands, using both observed and relative corrected abundances, indicated that relative corrected abundance adequately separates the effect of water depth from the effect of wetlands.