Does Riparian Forest Restoration Thinning Enhance Biodiversity? The Ecological Importance of Large Wood

Intact riparian ecosystems are rich in biological diversity, but throughout the world, many have been degraded. Biodiversity declines, particularly of vertebrates, have led to experimental efforts to restore riparian forests by thinning young stands to accelerate creation of large diameter live trees. However, many vertebrates depend on large diameter deadwood that is standing as snags or fallen to the forest floor or fallen into streams. Therefore, we reviewed the sizes of deadwood and live trees used by different vertebrate species to understand which species are likely to benefit from different thinning treatments. We then examined how riparian thinning affects the long‐term development of both large diameter live trees and deadwood. To this end, we used a forest growth model to examine how different forest thinning intensities might affect the long‐term production and abundance of live trees and deadwood. Our results suggest that there are long‐term habitat tradeoffs associated with different thinning intensities. Species that utilize large diameter live trees will benefit most from heavy thinning, whereas species that utilize large diameter deadwood will benefit most from light or no thinning. Because far more vertebrate species utilize large deadwood rather than large live trees, allowing riparian forests to naturally develop may result in the most rapid and sustained development of structural features important to most terrestrial and aquatic vertebrates.     

Entry and toxicity of organic pesticides and copper in vineyard streams: Erosion rills jeopardise the efficiency of riparian buffer strips

The present study was performed to characterise in-stream pesticide exposure within the Palatinate vineyard region in south-west Germany, evaluate the influence of buffer strip widths and identify mitigation measures for the relevant entry pathways. In-stream water and sediment samples that were taken at nine sampling sites of different buffer widths following intense rainfall, and edge-of-field runoff that were sampled in erosion rills were analysed regarding 28 active ingredients of pesticides including copper. In-stream samples contained a mix of 8 ± 4 pesticide compounds, resulting in total pesticide concentrations of 1.4-8.9 μg l⁻¹ for water and 16-670 μg kg⁻¹ dw for sediment. Following an exceptional rainfall event with a previous 34-day drought period, pesticide concentrations reached 7.0-83.4 μg l⁻¹. Fungicides were the most important pesticides found and were significantly correlated with the pesticide application frequency and rate. The calculated toxicity values per sample (TU_max) indicated that both organic pesticides and copper concentrations likely cause ecotoxicological effects in the field. The buffer strip width was of little importance for pesticide in-stream concentrations because pesticide entry occurred mainly via the field path network and erosion rills. Pesticide in-stream concentrations were significantly and positively correlated with the concentrations detected in erosion rills (R² = 0.56). As possible risk mitigation measures, we suggest the implementation of grassed field paths and vegetated ditches or wetlands.     

基于气囊缓冲的某火箭炮着陆冲击分析

目的减小火箭弹着陆冲击加速度。方法基于LS-DYNA瞬态动力学分析软件和冲击动力学理论,采用有限元软件HYPERMESH建立火箭炮-气囊系统有限元模型,采用显式动力学方法对火箭炮-气囊系统的着陆冲击缓冲过程进行仿真。分析火箭炮在正常着陆工况下,火箭弹的着陆冲击响应,得出空投装备速度、加速度变化曲线,以及气囊的体积、压力曲线。结果在正常着陆工况下,火箭弹横向加速度的最大值为122 m/s2,小于安全的横向加速度;火箭弹纵向加速度的最大值为48.3 m/s2,小于安全的纵向加速度;火箭弹的最大轴向力为2640 N,小于安全闭锁力。结论在火箭炮着陆冲击过程中,气囊缓冲装置吸收了大部分冲击能量,起到了良好的缓冲作用,火箭弹的冲击加速度、闭锁力均在安全范围内。采用显式动力学方法对火箭炮的着陆冲击过程进行分析是可行的。     

VALUE OF WOODY RWER CORRIDORS IN LEVEE PROTECTION ALONG THE MISSOURI RWER IN 19931

ABSTRACT: Following the Midwest flood of 1993, a study was initiated along a 39-mile segment of the Missouri River to determine if there was an association between woody corridors and levee stability. A systematic sample of levee failures revealed that primary levees which did not fail had a significantly wider woody corridor than failed levees. Analysis of the total inventory of failed levees revealed that as the width of the woody corridor decreased, the length of the levee failure increased. Number of levee failures and their severity of damage could be reduced if woody corridors were at least 300 feet wide.     

美国州法中的内径流水权及其优先权日问题

美国水资源的所有权属于各州 ,是一种公有的资源。法律上的水权 ,是水的使用权 ,主要包括私人所有的先占权水权、岸边权水权。在美国西部各州的水权系统中 ,有一种水权现在可以在私法框架中协调环境保护目标、各种取水权人的取水需求 ,这两者之间的冲突。这就是现在美国学术界广泛关注的内径流水权。内径流水权可以在私法领域保护水流的天然禀赋 ,并且排除政府以环境法为理由介入水事争端。随着环境主义在美国的破产[1] ,美国西部开始了大规模的水权裁决活动 ,通过水法院或者行政机构确认私有水权的优先权日 ,从而确立水权的优先权序列。这样水权就会真正成为属于分散的个体的、排他性的财产权。优先权日在先的水权将在枯水季节排除他人的取水权或者其他种类的用水权。因此 ,确立内径流水权在这个优先权序列中的地位 ,是环境保护目标在私法体系中 ,而不是在效率低下的各种环境保护法中 ,长久地得到维护的关键。内径流水权优先权日有 (1)判例法认定的日期 ;(2 )法律规定的日期 ;(3)转化生成的日期。在先占原则框架中扩张这种财产权可以更大程度地排除环境法的适用范围。     

The influence of ClO− and acidity in the reaction between H2O2 and CuCl2

The potentially explosive reaction of hydrogen peroxide (H₂O₂) and copper chloride (CuCl₂) was investigated. Pressure tests revealed that the reaction was strongly temperature - dependent and can easily undergo runaway reaction. Nevertheless, there was only a slight pressure increase at the low temperatures studied or when using low concentrations of CuCl₂. Under the conditions generating the slight pressure increase, hypochlorite anions (ClO⁻) are generated and the acidity increases. As the reaction reaches completion, ClO⁻ disappears, and the acidity decreases. Interestingly, the addition of phosphate buffer to maintain the weakly acid conditions led to a runaway reaction, and the use of basic ClO⁻ promoted the exothermic reaction. Based on the results, acidity has a strong impact on the reaction behaviour.     

化工园区外围控制距离的确定及环境影响减缓措施

指出制定化工园区周边控制距离过程中需要考虑的重要因素,确定了化工园区外围控制距离中的严禁建设区域和缓冲区域的范围,为城市规划中化工园区外围地域的合理规划提出了依据。同时提出减缓化工园区对园区外影响的措施。     

Diverging response patterns of terrestrial and aquatic species to hydromorphological restoration

Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10–164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15–120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local- and regional-scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes.     

EFFECTS OF BEST MANAGEMENT PRACTICES ON FOREST STREAMWATER QUALITY IN EASTERN KENTUCKY1

ABSTRACT: Forest land managers are concerned about the effects of logging on soil erosion, streamflow, and water quality and are promoting the use of Best Management Practices (BMPs) to control impacts. To compare the effects of BMP implementation on streamwater quality, two of three small watersheds in Kentucky were harvested in 1983 and 1984, one with BMPs, the other without BMPs. There was no effect of clearcutting on stream temperatures. Streamflow increased by 17.8 cm (123 percent) on the BMP watershed during the first 17 months after cutting and by 20.6 cm (138 percent) on the Non-BMP watershed. Water yields remained significantly elevated compared to the uncut watershed 8 years after harvesting. Suspended sediment flux was 14 and 30 times higher on the BMP and Non-BMP Watersheds, respectively, than on the uncut watershed during treatment, and 4 and 6.5 times higher in the 17 months after treatment was complete. Clearcutting resulted in increased concentrations of nitrate, and other nutrients compared to the uncut watershed, and concentrations were highest on the non-BMP watershed. Recovery of biotic control over nutrient losses occurred within three years of clearcutting. The streamside buffer strip was effective in reducing the impact of clearcutting on water yield and sediment flux.     

RIPARIAN FOREST EFFECT ON LATERAL STREAM CHANNEL MIGRATION IN THE GLACIAL TILL PLAINS1

ABSTRACT: Dendrochronology analyses of point bar complexes were used to quantify the effects of riparian forests on local lateral migration of bends in seven streams in the glacial till plains of north central Missouri. Stream bends were paired with similar bank height, midchannel radius of curvature, soil composition, and watershed size. In each pair, one concave bank was forested and one was unforested. Stream bends with unforested concave banks had an average local migration rate three times greater than stream bends that had forested concave banks.