青冈栎混交林生物量及碳储量分布特征

以湖南永顺43年生青冈栎混交林为研究对象,采用平均木法和样方收获法测定乔木层生物量和林下植被层生物量,采用重铬酸钾—水合加热法测定样品碳素含量,对林分各组分的生物量和碳储量分布特征进行研究。结果表明:青冈栎混交林单位面积生物量为320.03t/hm~2,各组分单位面积生物量由大到小的排列顺序为乔木层、枯落物层、灌木层和草本层。林分单位面积碳储量高达389.43t/hm~2,其中植被层和土壤层分别为249.02,140.41t/hm~2。林分内青冈栎、栲树和杉木单株平均蓄积分别为0.156 1,0.2912,0.296 0m~3,单株平均碳储量分别为103.85,99.15,97.90kg。青冈栎属于生长速度较慢但木材密度大的树种,单株平均蓄积仅有栲树和杉木的单株平均蓄积的1/2左右,但其单株平均生物量和碳储量却比栲树和杉木的单株平均生物量和碳储量要高,表明树种碳汇能力的高低并不完全取决于树种生长速度的快慢,这对今后生态公益林树种的选择提供了一个新的方向。     

Variation in prey selection and foraging success associated with early‐life ontogeny and habitat use of American paddlefish (Polyodon spathula)

Many fishes are planktivorous during early life and switch to piscivory or consume larger food items as ontogeny progresses. In contrast, paddlefish start as particulate feeders and later become filter feeders. Few studies have identified food items essential for paddlefish growth, survival and recruitment surrounding this ontogenetic diet shift. The objectives of this study were to investigate (i) prey types consumed by paddlefish, (ii) variability in prey selection surrounding an ontogenetic diet shift and (iii) whether habitat affected paddlefish prey selection or foraging success. We analysed gut contents of 189 wild age‐0 paddlefish from the middle Mississippi River (MMR) and also conducted a laboratory experiment to address these objectives. We found that paddlefish primarily foraged on benthic macroinvertebrates in the MMR, which differed from previous studies in lentic systems, suggesting young paddlefish prey selection may be labile depending on habitat (i.e., lotic versus lentic). Dominant prey of wild‐caught and experimental age‐0 paddlefish were caddisfly larvae (Trichoptera), followed by hemipterans and amphipods. We found little evidence that habitat attributes affected foraging success, but the most common prey items consumed were associated with wing dike habitat and the upstream and downstream tips of alluvial islands. Our experimental study revealed that if provided a mixture of organisms, age‐0 paddlefish will primarily consume macroinvertebrates while age‐1 paddlefish will mainly filter zooplankton. Overall results suggest young paddlefish prey selection can be highly variable, but also heavily reliant on a narrow group of prey resources.     

Study on Decision Method in Choosing MIS Softwares for Manufacturing Enterprises

The decision objects and evaluation target architecture in choosing Management Information Systems (MIS) softwares for manufacturing enterprises are proposed. Fuzzy mathematics comprehensive evaluation method is used in decision analysis. The method in is applied practically.     

薪炭林植物选择指标数值分析

根据薪炭林植物应具有热值高,抗旱性强的特点,文章选择了产量、热值、水势、组织含水量、自由水/束缚水和自然饱和亏六个特征指标,在单指标分析的基础上,又应用数值分析技术选出了沙棘、狼牙刺、山桃、柠条、沙打旺、草木樨、苜蓿、红豆草共8个优良的薪炭林植物种。     

Factors influencing male mating success in bur oak,Quercus macrocarpa

Pollen donors of acorns and saplings in a stand of bur oak were identified by paternity exclusion using microsatellite genotype analysis. Here we examine the influence of several factors likely to affect reproductive success of males with wind-dispersed pollen, including distance of pollen donor from maternal tree, genetic relatedness of pollen donor to maternal tree, direction of pollen donor relative to maternal tree, and size of pollen donor (crown volume and trunk diameter). Surprisingly, none of these factors were strongly correlated with fertilization success, although weak but significant correlations with crown volume and distance were found. The slight influence of distance is actually overestimated here, because our analysis necessarily excluded a large proportion of pollinations that were effected by trees outside the stand. The pollen donors outside the stand were not identified, but were more than 150 meters away. Pollination patterns in this stand of bur oak are quite complicated. Seed parents were fertilized by multiple pollen donors within the stand from all directions and as far as 200 m away. These results caution against the use of models of pollination that are based on simple distance or directional parameters because they will not adequately predict gene flow or male reproductive success. Our results further emphasize the importance of genetically identifying successful pollen donors rather than relying on patterns of physical movement of pollen.     

转变四川农业发展方式的困境与途径研究

加快农业发展方式转变是实现传统农业向现代农业转变,实现农业可持续发展能力和促进农民持续增收的关键。文章以四川省为例,分析了四川现代农业发展面临着的粮食安全与结构调整、投入不足与要素流失、劳动力富余与结构性短缺、生产发展与可持续发展等困境,认为要转变农业发展方式,必须要发展适度规模经营,加快科技创新,不断延长农业产业链和拓展农业多功能,大力发展特效效益农业,走可持续发展之路。     

我国利率市场化改革的道路选择

分析我国利率市场化面临的约束因素以及我国利率市场化存在的有利条件,提出我国利率市场化的战略选择。     

Nature orientation and opportunity: Who values and who has opportunity for satisfactory green spaces in proximity to their place of residence

Urban green spaces (UGS) provide important contributions to people. Yet, UGS planning requires better understanding of by whom and where such contributions are being valued or missed. Based on a mixed-methods online survey and choice experiment with residents of Wellington in Aotearoa New Zealand, we analyse how much and why residents value UGS and their benefits when deciding where to live and how socio-economic and spatial factors might impact nature orientation and opportunity for satisfactory local UGS. We find that local UGS are an important residential choice criteria for the majority of respondents, especially in the context of Wellington’s intensification plans. However, we show that socio-economic and spatial factors significantly impact whether someone values and is satisfied with UGS in proximity to their place of residence. Our findings call for careful scoping of a city’s population and spatial structure when planning for equitable UGS provision. More holistic approaches to green space planning are needed to address contextualities and the complex interdependencies between nature orientation and opportunity and to plan for green space distributions that provide opportunities now and help shaping nature orientation for future generations.     

海南休闲农业产业发展的条件与策略研究

依托独特的休闲农业资源和国家政策的大力支持,休闲农业已经成为促进海南农村产业结构调整、农民持续增收及城乡统筹发展的主要产业之一。为此,运用SWOT分析法解析海南热带休闲农业发展的优势、弱势、机遇、挑战等条件,并针对性地指出寻求海南休闲农业向更深层次发展的策略,旨在对海南休闲农业的发展提供建设性意见。     

Sustainable Aquaculture Products: Implications of Consumer Awareness and of Consumer Preferences for Promising Market Communication in Germany

Sustainability issues are becoming increasingly important in Western food consumption. This research aims at identifying ways to increase the market share of sustainable fish from aquaculture by analyzing consumer awareness and preferences for sustainable aquaculture products and by drawing conclusions on improving communication in the German market. An integrative research approach was used: it began with an inventory of sustainable seafood products on the German market, followed by qualitative and quantitative consumer research, and ending with a stakeholder workshop, which reflected on the research outcome with practitioners. Sustainability and country of origin proved to be of minor relevance to the vast majority of the consumers interviewed. Indeed, attributes such as freshness, taste, and price frequently ranked higher. Like most of the other consumers, the small consumer segment that is generally interested in sustainability issues of food also often lacks knowledge of fish farming and its products. Consequently, communication of sustainability in aquaculture is challenging, and the development of this market requires concerted actions along the whole value chain, with the retail sector as the main actor.