上部烟叶一次性采摘按叶位分置烘烤对烟叶质量的影响

设置K326上部烟叶6片叶一次性采收后按叶位(从上往下)分置烘烤(设3片叶置于同一烤箱、2片叶置于同一烤箱和6片叶置于同一烤箱(对照)),分析烤后烟叶的单叶质量、含梗率、外观质量及等级结构,并对烤后烟叶的化学成分协调性与感官质量进行评价。结果表明：①上部叶按叶位两两分置3个烤箱烘烤,上部叶5和上部叶6单叶质量比同一烤箱烘烤分别提高了9.4%和11.2%,上部叶1至上部叶6的含梗率分别降低5.2%、3.3%、2.5%、6.9%、8.7%和13.1%;②分置烘烤深(金)黄、成熟、疏松、油分多、色度浓强的烟叶在总烟叶数中所占比例均显著高于置于同一烤箱烘烤;③分置烘烤能显著提高上等烟所占比例,在上部叶1至上部叶3中,分置3个烤箱烘烤,B1F烟叶提高了8.54个百分点,B2F烟叶提高了48.4%;在上部叶4至上部叶6中,分置3个烤箱烘烤,B1F和B2F烟叶分别提高了195.6%和10.5%;④按叶位分置烘烤,烟叶还原糖含量、两糖比值及糖碱比值比同一烤箱烘烤均显著提高(P＜0.05);⑤按叶位分置烘烤烟叶的香气量、柔和细腻度、刺激性、余味、杂气等的得分及感官质量评吸总分都高于放置于同一烤箱烘烤的。     

海洋捕捞业与海洋生物多样性的持续有效发展——基于海洋生物经济学模型的分析

海洋捕捞业的经济有效性和海洋生物种群的保护是当前海洋渔业经济研究的重点,应该将相关海洋物种的捕捞和繁殖规律统筹考虑,提高海洋渔业资源的利用效率。通过对Ｆｌａａｔｅｎ的生物经济学模型的数理分析比较,提出经济鱼种的价格上涨并不会导致该鱼种生物种群存量下降,如果管理措施合理,鱼类种群存量依然存在上升的可能;并由此指出海洋捕捞必须考虑种群间相互关系,利用合理的生物经济学模型、建立明晰的海洋捕捞权等措施有助于海洋生物经济的持续有效发展。     

Mathematical models of population dynamics of the kelp Laminaria religiosa, with emphasis on temperature dependence

Theoretical and numerical models were developed to investigate the effects of water temperature on the population dynamics of the kelp, Laminaria religiosa . The models describe seasonal changes in the biomass of kelp by calculation of growth and grazing rates of sea urchins, Strongylocentrotus nudus . Using the theoretical model, conditions were obtained to satisfy the statistical analysis of a relationship between water temperature and kelp harvests from a fishery census. The conditions require the negative second derivative of the growth rate with respect to temperatures, or the positive second derivative of the grazing rate. By using the numerical model, harvests of kelp were calculated for a change in water temperature over a given period. The period of a temperature change giving the maximum effects on the harvest was determined primarily by temperature dependence on the growth rate. Grazing by sea urchins had large effects on the harvest of kelp. A value of 10⁴ was obtained for a ratio between harvests at the higher and the lower temperatures differing by ± 1^∘C.     

Towards sustainable fisheries and aquaculture management in the African Great Lakes

Inland fisheries play important roles in food and economic security in the riparian countries surrounding the Great Lakes of Africa. However, the lakes are being systematically degraded by anthropogenic pressures, in combination with the huge population growth prevalent in the region. This paper summarises the outcomes of an international conference to develop a ‘Strategy for Conservation and Sustainable Development of the African Great Lakes Region in a Changing Climate’, held in Uganda in 2017, with particular attention on the potential for fisheries and aquaculture. The paper highlights options for addressing the problems facing the aquatic resources and specifically the importance of effective management of the fisheries and ecosystems of the Great Lakes to achieving the UN Sustainable Development Goals to ensure food and nutritional security and sustainable livelihoods. There is need to improve fisheries assessment and determine the value of the fisheries (and aquaculture). Fisheries legislation, regulation and enforcement need revision and co‐management mechanisms require rethinking. There is considerable potential for aquaculture, and especially cage culture, to increase fish production, but there is an urgent need to address technical, social, environmental and input requirements. It is also imperative that best practices guidelines are developed that will support cage culture production practices.     

Harvest models and stock co‐occurrence: probabilistic methods for estimating bycatch

A primary goal of ecosystem‐based fishery management is to reduce non‐target stock impacts, such as incidental harvest, during targeted fisheries. Quantifying incidental harvest has generally incorporated fishery‐dependent catch data, yet such data may be biased by gear non‐retention, observation difficulties, and non‐random harvest patterns that collectively lead to an impartial understanding of non‐target stock capture. To account for such issues and explicitly recognize the combined influence of ecological and harvest factors contributing to incidental capture within targeted fisheries, we demonstrate a probabilistic modelling framework that incorporates: (i) background rates of target and non‐target stock co‐occurrence as the primary ecological basis for incidental harvest; (ii) the probability of harvesting at localities exhibiting co‐occurrences; (iii) the probability of selecting for non‐target species with fishery gear; and, (iv) as a function of harvest effort, the overall probability of incidental capture for any non‐target stock contained in the species pool available for harvest. To illustrate application of the framework, simulation models were based on fishery‐independent data from a freshwater fishery in Ontario, Canada. Harvest simulations of empirical stock data indicated that greatest species‐specific capture values were over 4000 times more likely than for species with lowest values, indicating highly variable capture probabilities because of the combined influence of stock heterogeneity and harvest dynamics. Estimated bycatch–effort relationships will allow forecasting incidental harvest on the basis of effort to evaluate future shifts in fishing activity against specific ecosystem‐based fishery management objectives, such as reducing the overall probability of bycatch while maintaining target landings.     

The nexus of fun and nutrition: Recreational fishing is also about food

Recreational fishing is a popular activity in aquatic ecosystems around the globe using a variety of gears including rod and line and to a lesser extent handlines, spears, bow and arrow, traps and nets. Similar to the propensity to engage in voluntary catch‐and‐release, the propensity to harvest fishes strongly varies among cultures, locations, species and fisheries. There is a misconception that because recreational fishing happens during non‐work (i.e. leisure) time, the nutritional motivation is negligible; therefore, the role of recreational fishing in supporting nutrition (and thus food security) at regional, national or global scales is underappreciated. We consider the factors that influence whether fish will be harvested or released by examining the motives that underlie recreational fishing. Next, we provide an overview of the magnitude and role of recreational fishing harvest in supporting nutrition using regional case‐studies. Then, we address issues such as contaminants and parasites that constrain the ability of fish harvested by recreational fishers to be consumed. Although recreational fishing is foremost a leisure activity, the harvest of fish for personal consumption by recreational fishers has contributed and will continue to contribute to human nutrition by providing an accessible, affordable and generally highly sustainable food source, notwithstanding concerns about food safety and possibly overfishing. Attempts to better quantify the role of fish harvested by recreational fishers and the relative contribution to overall food security and personal nutrition will provide resource managers and policymakers the information needed to guide management activities and policy development.     

不同收获期扭黄茅种子萌发特性研究

采用4个不同收获时期的扭黄茅种子进行萌发试验,设置了6个萌发温度、5个干旱胁迫强度,分别测定了不同收获时期扭黄茅种子的发芽率,发芽势和萌发指数,并进行了统计分析。研究结果表明：扭黄茅花期长,不同收获期的种子发芽率存在差异。同一生育期,以4月收获的扭黄茅种子活力为好。不同温度和PEG胁迫强度处理下,扭黄茅种子均在2～5d萌发。40℃时,常温条件下贮藏一年的种子比新收获的同期种子对高温的忍受能力强。-6Pa时,常温条件下贮藏一年的种子对干旱有较好的忍耐性。     

森林动态计算机模拟模型研究

综述了国内外目前广泛应用的6种森林动态计算机模型:森林收获模型、生态林窗模型、生态分室模型、过程模型、植被分布模型和混合模型。在介绍每种森林动态模型时, 分别选取几个典型的计算机模拟模型, 来评述每种森林动态模型的优缺点, 并在此基础上探讨今后森林动态模型的发展趋势。     

人类活动对森林景观影响研究进展

从影响森林景观的人为活动的性质入手,将人类活动分为两类:土地利用和森林经营,分别阐述其研究现状.土地利用主要包括农业开发和城市化,通常使林区转变为非林区.森林经营活动主要包括采伐和修建道路.采伐影响森林格局和动物生境,前者侧重于采伐参数和格局结构特征之间关系的研究,后者着重于从动物生境保护角度设计采伐格局;修建道路会改变景观格局和过程,近期焦点为道路网空间结构特征与景观格局的关系、该关系在不同尺度下的表现规律及道路影响下景观过程变化.目前,在中国道路研究尚未引起重视.本文对中国进行人类活动对森林景观影响研究中存在的问题进行了总结:1)人类活动作用的时空格局定量化是人类活动影响研究的前提,这方面研究较少,阻碍了研究的深入进行;2)目前,各种模型的开发、应用仍方兴未艾,模型验证及灵敏度分析是难点和热点,中国处在模型应用的起步阶段,亟待发展适合自身特点的空间直观模型;3)该领域开始从格局研究向过程研究深入(如景观格局与动物生境关系、森林格局与水文过程关系的研究),前者重点解决动物的迁移、分布和景观格局的关系,我国受动物行为学研究较薄弱的制约而仅限于生境描述和分析,后者从格局出发,以景观生态学的空间异质性理论,强调森林水文功能对采伐面积、强度、方式、伐区空间位置的响应;4)多数地区的森林景观动态深受政策影响,研究其对典型政府决策反应的方向和速率,能为森林经营和自然保护的科学决策提供重要依据.     

食用豆联合收获减损技术与策略分析

食用豆是我国重要的食用作物,推进其机械化收获提质减损是促进产业发展的重要手段。由于食用豆种类多、地域分布广、种植模式多样,其高效收获装备较为缺乏,是当前生产中迫切需要解决的短板技术问题。结合国内外食用豆产业发展现状、当前联合收获技术研究成果和食用豆机械化收获的特殊性,在对现有联合收获技术的适用性进行分析的基础上,提出适合我国食用豆生产的机械化减损收获技术策略。主要措施包括综合考虑宜机化品种筛选及配套种植农艺、联合收获各环节协同作用和机手收获技能减损。利用以上手段可有效降低收获割前损失、割台损失、脱粒损失和清选损失,同时通过集成应用低损收获割台、高效脱粒清选和物料低损输送技术,可大幅降低食用豆联合收割机作业损失率,减损效果显著。