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.     

国内土壤环境污染防治进程及展望

综述以中国2005—2019年土壤污染防治进程的3个阶段为主线,总结土壤污染防治发展过程中管理模式、治理体系、管控要求、机构改革、立法支持等5个方面重要转变,分析国家和地方土壤环境保护标准、法律法规政策和主要土壤污染治理成效。针对国内土壤污染防治未来发展趋势,从完善土壤环境标准及管理制度、建设监测及预警大数据平台、加强土壤生态环境国际合作、持续推进土壤修复技术攻关和先行区经验推广等方面提出建议,以期为生态环境高水平保护和经济社会高质量发展提供参考。     

突出生态园林思想提高城市道路绿化水平

在总结城市道路绿化的经验及教训的基础上，提出城市道路绿化的规划设计要突出体现“生态园林”的指导思想；在重视城市干道绿化的同时，要进一步加强小街小巷的绿化工作；在树种选择上要做到多样性和地带性相统一；进一步强化道路绿地的养护管理工作，是尽快形成总体效果、发挥生态效益的有力保证。     

臭椿、新疆杨混交林对光肩星天牛选择寄主行为的影响

利用3年生臭椿、新疆杨在室内建立混交林进行光肩星天牛成虫放飞试验.结果表明:臭椿、新疆杨混交林对天牛成虫的寄主选择有显著影响,天牛成虫的交尾行为只在新疆杨植株上进行;天牛成虫在林内植株上着落的总虫次随新疆杨株数的减少而下降,交尾次数也减少;臭椿、新疆杨植株数量在林分中所占比例在一定范围时,天牛成虫在新疆杨和臭椿上着落的虫次比均趋于稳定;新疆杨与臭椿以行状3:2和2:3混交时林分的抗虫效果较好.     

Determinants of equity-based entry mode choice in the forest sector: the case of China

The focus of foreign direct investment (FDI) in the global forest sector has shifted from developed to developing economies (currently accounting 73% of total) during the past two decades. China has been the main global driver with its annual FDI soaring from USD 130 million in 2002 to USD 550 million in 2010. In light of international economic and business theories, choice of foreign entry mode is considered the most critical issue in corporate expansion strategy, which, however, has not been empirically studied in the forest sector. To fill this gap, our paper focuses on modeling two equity-based entry mode choices (i.e. wholly owned subsidiary or joint ventures) of foreign investment projects in China based on data from 109 activities of the Top 100 forest, paper, and packaging industry companies. By using logistic modeling, the main determinants of corporate entry mode choice are found to be cultural and geographical distance between the corporate home country and China, duration of corporate presence in China, and spatial concentration of local-level forest industry. Instead, investment project size and local resource availability are found to have no significant impact on corporate entry mode choice in China.     

湖北省高等院校干道绿化和广场绿化建设的探讨

科学进行干道和广场的绿化规划与树种选择 ,对全面提升校园景观质量具有重要的意义。结合当前湖北地区部分高校干道绿化和校园广场绿化建设中存在的一些问题 ,介绍了干道和广场的绿化规划和树种选择原则 ,并详细探讨了适合湖北地区高校种植的干道绿化树种和广场绿化植物。     

观赏竹盆景艺术创作研究

观赏竹盆景是盆景中的一朵奇葩。本文较为全面地阐述了观赏竹盆景的制作方法,包括竹种选择、前期培育、艺术创作和管理养护等。用观赏竹来制作盆景大大提高了竹子的附加值,拓宽了盆景选材范围,并且经济效益显著。     

农业专业镇中小微企业服务平台发展战略初探——以广东省为例

农业专业镇是广东省农村经济发展的重要推动力。如今农业专业镇的发展面临着结构调整、产业升级和增长方式转变的巨大挑战，服务平台发展的战略选择对农业专业镇发展至关重要。专业镇的中小微企业服务平台建设发展呈现出以创新为核心、产学研紧密结合的趋势：加快中小微企业服务平台发展，在战略上必须以政府为主导，市场化配合运作，将载体建设与功能培育协同运作，将产学研合作与联盟服务协同运作，将品牌建设与重点扶持紧密结合，形成协同运作体系网。     

草地贪夜蛾对小麦的为害风险:取食为害性及解毒酶活性变化初探

为了探究草地贪夜蛾对小麦的为害风险,我们以取食玉米作为对照,开展研究取食小麦对草地贪夜蛾的存活率、取食选择性、生长量和3种解毒酶及乙酰胆碱酯酶的影响。结果表明:草地贪夜蛾初孵幼虫在小麦上的存活率与玉米并无显著差异,高达90%以上。用小麦连续饲喂3龄幼虫7 d,日均体重增加迅速,与取食玉米无显著差异(P0.05)。2龄幼虫取食选择率为小麦玉米,3龄和4龄幼虫的取食选择率为玉米小麦,但均无显著差异。值得注意的是,小麦饲喂48 h后草地贪夜蛾谷胱甘肽S-转移酶活性和多功能氧化酶含量表现为显著诱导上升,而羧酸酯酶和乙酰胆碱酯酶的活性无显著变化。本试验结果初步表明草地贪夜蛾存在为害小麦的风险,应加强草地贪夜蛾在麦田发生情况的监测,同时应重视草地贪夜蛾取食不同寄主对药剂敏感性机制的研究。