Rehabilitation and improvement of Guilin urbanwater environment: Function-oriented management

Economicdevelopment and population growth havedeeplydamaged the urbanwater environment of Guilin City, China. Main problems involved structuraldamage and functionaldeterioration of the urbanwaters. An integrated technical schemewasdeveloped to rehabilitate the urbanwater environment and to enhance thewaters＇ functionsduring 1998-2008. Improvement ofwaters＇ functions includedwater system reconstruction,water pollution control,water safety assurance, and aquatic ecological restoration. Thewater systemwas reconstructed to connectdifferentwaters and cleanwater supplies to the lakes. Moreover,water pollutionwas controlled to improvewater quality by endogenous pollutant elimination and extraneous pollutant interception. In addition, ecological measures put in place serve to enhancewater system functions and better benefit both nature and humans. The project has brought about sound ecological, economic and social benefits in Guilin City,which can potentially be extended to similar cities.

Research on retention forestry in Northern Europe

Retention approaches in forest management are today common in several North European countries,integrated into the clearcutting practice as a way to promote biodiversity and maintain ecosystem functions.Individual green trees and retention patches(tree groups)are retained at final harvest,and deadwood is left at site or created.Here,we review research on retention in Sweden,Finland,Norway,the Baltic States,and NW Russia,with special focus on biodiversity.Following the first publication in 1994,about 180 peer-reviewed articles have been published.We present results from a systematic search of the retention literature,separated into the following topics:buffer zones,retention patches,high stumps,other types of deadwood,European aspen Populus tremula,and cost-efficiency.Russian literature is synthesized separately since studies from this region have so far almost exclusively been published in the Russian language.Furthermore,we describe six ongoing large-scale,replicated experiments with varying retention levels,five in Finland and one in Sweden,and summarize their main results.Among main conclusions for practice from the literature and experiments are that retention patches as large as 0.5 ha and 10-mwide buffers to watercourses are not enough to maintain pre-harvest species composition but survival of forest species is still larger than on conventional clearcuts.Deadwood on clearcuts may present important habitats to saproxylic species,including rare and red-listed ones and a prioritization of tree species per stand is recommended.We identify several important future research directions including switch of focus towards the landscape as well as the species population level.Surveys in parts of European Russia where retention has been unintentionally implemented already for a century would indicate possible future trajectories of biodiversity and their drivers in other regions of Northern Europe.A stronger link to ecological theory would help in study designs and in the formulation of predicted outcomes.

A new static induction thyristor with high forward blocking voltage and excellent switching performances

A new static induction thyristor （SITH） with a strip anode region and p- buffer layer structure （SAP-B） has been successfully designed and fabricated. This structure is composed of a p- buffer layer and lightly doped n- regions embedded in the p＋-emitter. Compared with the conventional structure of a buffed-gate with a diffused source region （DSR buffed-gate）, besides the simple fabrication process, the forward blocking voltage of this SITH has been increased to 1600 V from the previous value of 1000 V, the blocking gain increased from 40 to 70, and the turn-offtime decreased from 0.8 to 0.4μs.

Appraising trapping efficiency of vegetative barriers in agricultural landscapes:Strategy based on a probabilistic approach based on a review of available information

Vegetative barriers have proven their effectiveness in controlling water erosion and enhancing other ecosystem services in agricultural areas.This characteristic has led to the conservation and promotion of vegetative barriers as landscape elements by the Common Agricultural Policy and other policy initiatives.Numerous reviews have dealt with the trapping efficiency of vegetated barriers,although they usually focus on studies from humid climates where their implantation and survival are more favourable.However,vegetated barriers are also an attractive alternative in arid and semi-arid climates.They limit competition for water and nutrients with crops to a reduced area compared to other best management practices,such as cover crops.This study presents a review of trapping efficiency of sediment,runoff,and nutrients(P and N)by vegetative barriers in regions of humid and arid,and semi-arid,climates,and a strategy based on sediment trapping efficiency probability,which in turn is based on the results obtained from our review.Different types of independent variables were grouped and identified for the review:related to the vegetative barrier dimension(buffer width,slope of the plot,and buffer area ratio),and related to the experimental conditions(type of vegetation in the buffer,soil protection of the non-buffered area,type of climate,type of experimental measurement and origin of rainfall).An explor-atory analysis evaluated the significance of the experimental variables,which identified the need to focus on experiments under natural rainfall since those carried out with simulated rainfall presented statis-tically significant differences.In general,average trapping efficiencies for runoff and sediment were 40.1 and 62.6%,respectively.For nutrients,values of trapping efficiencies had an average of 44.9%for phosphorus and 38.4%for nitrogen.Runoff and sediment trapping efficiency in arid and semi-arid re-gions tended to be higher than in humid regions.Regarding dimensional variables,a positive trend was observed in the runoff and sediment trapping efficiency with the width of the vegetative barrier,with a large variability across all the width range.Finally,based on the results of our review,we developed a probabilistic model for sediment trapping efficiency as a normalised cumulative probability distribution function for the two climatic regions separately.Also,we developed it as a function of the width of the vegetative barrier for each climatic region,to facilitate decision-making.This model shows that in 92%of the cases,a vegetative barrier will reduce erosion in humid climates,while this trapping efficiency will be 100%in semi-arid and arid conditions.This analysis showed that vegetative barriers are an alternative to other best management practices,e.g.cover crops,when there are operational or agronomic impedi-ments to their implementation,having a high success rate in reducing erosion in any agricultural area.