Ecological drivers of fish metacommunities: Environmental and spatial factors surpass predation in structuring metacommunities of intermittent rivers

Metacommunity theory is a new approach for explaining how local and regional processes contribute to community organisation and integrative studies are needed to fully characterise the processes underlying its structure and function. We analysed, through variation partitioning and distance decay relationships, how metacommunities of fish in pools of intermittent rivers are structured by environmental, species interaction and spatial factors. The results indicate that both species sorting and dispersal limitation (spatial factors) were important in shaping fish metacommunities. Species sorting was the most influential driver within fish metacommunities, but predation was much less relevant and did not show any pure effect in metacommunity structure. However, environmental factors were determinant among metacommunity patches.     

基于不同空间插值法的黄海和东海北部游泳动物多样性空间分布研究

物种多样性空间分布是生态学研究的重要内容之一，空间插值法在该领域应用广泛。本研究以2017年5月黄海和东海北部游泳动物多样性为例，选取种类数(S)、Shannon-Weaver多样性指数(H′)、Pielou均匀度指数(J)和Margalef丰富度指数(d)来衡量该海域物种多样性，应用反距离加权法(Inverse distance weighted, IDW)、径向基函数法(Radial basis function, RBF)、局部多项式法(Local polynomial interpolation, LPI)、普通克里格法(Ordinary kriging, OK)和协同克里格法(Ordinary cokriging, COK)对上述4种多样性指数进行插值，通过jackknife检验的方法选择适合每种多样性指数的空间插值法。结果表明，对于4种多样性指数，COK结果均最好，而其他4种方法精度较低，且差别不大。COK预测结果表明，S和d都呈现出东南部高，北部次之，中部最低的格局。H′和J也是中部最低，在南部和北部海域差异不大。4种多样性指数在32?N以南海域的高值区范围大致相同。COK可以作为黄海和东海北部游泳动物多样性空间插值的方法。     

中国陆地区土地利用/覆被时空格局变化及驱动力分析

为了揭示21世纪初的10年,中国陆地区域土地利用格局的时空变化,基于全球30 m地表覆盖遥感数据产品(GlobeLand30),采用定性分析与定量分析相结合的方法,在中国陆地区域和流域尺度上,对10年间的土地利用转移矩阵与土地利用动态度进行实证研究。结果表明：研究区内土地利用类型主要以草地、森林和耕地为主,其中草地、耕地和湿地面积不断减少,分别减少了140413、20480、692 km ²,裸地和人造地表的面积增长的比较明显,增长了99645、26302 km ²;草地—裸地、草地—森林之间的转化较为剧烈,灌木地和人造地表的变化速率最大,达1.80%。各子流域内,土地利用类型时空格局变化不同,大部分流域以草地、耕地和森林为主。区域内草地、裸地和人造地表类型的变化明显,人为因素对土地利用格局的影响较大且活跃,自然因素的影响较为持久和稳定。     

Impacts of culture survival rate on culture cost and input factors: Case study of the hard clam (Meretrix meretrix) culture in Yunlin County,Taiwan

This study applies a translog cost function model to analyze the culture costs and the use of input factors among three groups of hard clam farmer households in Yunlin County, Taiwan, with different survival rates (low-intermediate, intermediate-high, and high). The study found that farmer household production in the three observed groups all exhibited economies of scale and could significantly expand the scale of production to lower the average cost. For farmer households with high survival rates, production cost could be reduced by 2.16% by a 10% increase in output. Moreover, the study shows that the survival rate–cost interaction values of farmer households in the intermediate-high and low-intermediate survival rate clusters were negative. Therefore, any increase in the survival rate could help lower the culture cost of farmer households. For low-intermediate farmers, the survival rate–cost interaction value was the most negative; any increase in the survival rate by 10% would decrease the cost per hectare by NT$23,424. For high survival-rate households, seeding and capital were substitutes, and seeding and feed were complements. As such, farmers would reduce the use of seeding factors when increasing the use of capital and decreasing the use of feed.     

The hidden value of artisanal fisheries in Honduras

Declining fisheries catches are a global trend, with management failing to keep pace with growth in fishing effort and technological advances. The economic value of Honduras’ catches was estimated within the industrial and artisanal sectors. Catches were found to be 2.9 times greater than the official statistics between 1950 and 2015. The merging of industrial and artisanal catch data masked the decline in industrial catches and hid the strong growth of artisanal fisheries. In 1996, annual artisanal fisheries landed catches surpassed the industrial fishery sector, and in 2000, the annual net value of artisanal fisheries eclipsed the value of the industrial fisheries. These data highlight the importance of artisanal fisheries in Honduras and challenge the long‐held belief that the industrial sector contributes more to the national economy. The global paucity of fisheries data highlights the need for comprehensive strategies to collect more detailed and accurate fisheries data.     

Integrated crop and livestock systems in Western Europe and South America: A review

For many years, we have seen an increasing specialization of agricultural systems and territories, with a clear separation between territories with very high animal densities and those devoted to the growing of annual crops. This development is explained by market and sector economic logic and has been reinforced by the availability of low-cost inputs and animal housing systems based on direct grazing not requiring straw. It has, however, also involved negative environmental impacts and, in some cases, the impoverishment of soil fertility, a loss of biodiversity, and excesses of N and P, leading to eutrophication and hot spots of ammonia emission in livestock-breeding territories. Having recapped the mechanisms behind the specialization of systems and territories, we examined the extent to which the development of innovative mixed-farming systems that reconnect livestock and crop production on various territorial scales (farm, district, region) can reduce the negative impacts of agriculture on the environment, produce valuable ecosystem services and achieve acceptable economic efficiency for farming enterprises. Examples from temperate regions will be used to show that mixed-farming systems increase the possibilities of better recycling of nutrients within systems, limiting recourse to the purchase of increasingly expensive inputs and safeguarding the biodiversity of agricultural ecosystems.     

Expression of synaptophysin in hippocampal CA1 region and prefrontal cortex of PTSD rats

AIM:To investigate the expression of synaptophysin in the CA1 region of hippocampus and prefrontal cortex (PFC) of rats with posttraumatic stress disorder (PTSD), and to explore the mechanism of spatial memory changes in PTSD rats.METHODS:Healthy adult SD rats (n=36) were randomly divided into 2 groups:control group and model group, with 18 rats in each group. The rats in model group was continuously given single prolonged stress (SPS) to construct the PTSD model. Morris water maze (MWM) was used to test the learning and memory ability of the rats in the 2 groups. The protein expression of synaptophysin in the hippocampal CA1 area and PFC was examined by immunohistochemistry, Western blot and immunofluorescence experiments. RESULTS:The latency of the rats in searching for the underwater platform in model group was significantly longer than that in control group from the 2nd day (P<0.01) in the MWM experiment, the target quadrant swimming time was significantly shortened (P<0.01), and the times of crossing the platform were also significantly reduced (P<0.01). The results of immunohistochemistry, Western blot and immunofluorescence experiments showed that the expression of synaptophysin was obviously reduced in the CA1 region of hippocampus and PFC in model group as compared with control group (P<0.05 or P<0.01).CONCLUSION:The reduction of spatial memory ability in PTSD rats may be associated with the decreased expression of synaptophysin in the CA1 region of hippocampus and PFC.     

事务所所有权规模对审计收费的影响及检验

根据中国2007~2011年全部A股上市公司的年报数据，从理论上分析了会计师事务所所有权规模对审计收费的影响并进行了实证检验。研究发现有限责任会计师事务所所有权规模与审计收费显著正相关，即随着事务所所有权规模的增大，审计收费也增大。研究同时发现，相对于私有产权上市公司，事务所对国有产权上市公司的盈余管理收取了更高的审计费用。     

张掖市规模化羊场疫病综合防制技术研究

随着张掖市养羊业规模化、集约化程度的不断提高,羊的疫病也随之频发,呈现多系统混合感染、隐性感染、引入性疫病致病率高等特点,本文论述了规模化养羊场疫病综合防制的基本原则,提出了对规模化养羊场疫病综合防制具有指导意义的技术措施.     

基于牧户尺度的草原火灾风险评价——以东乌珠穆沁旗为例

随着全球气候变暖，草原火灾频发给牧区生境带来严重威胁，牧户生产生活行为对判断草原火灾风险具有重要意义。从牧户微观尺度出发，以东乌珠穆沁旗57个嘎查牧户为研究对象，依据自然灾害指数法，牧户调研和GIS方法，采用主成分分析法、层次分析法、加权综合评价法对牧户尺度草原火灾风险评价指标体系分析，获取东乌旗草原火灾风险等级分布图，并利用火点对风险区划精度验证。结果表明：1）东乌旗草原火灾风险评价4个一级指标的权重危险性25.85%、暴露性28.86%、脆弱性19.17%、防灾减灾能力26.12%。2）东乌旗草原火灾风险性整体呈由西到东逐渐递增的趋势，研究区绝大多数地区属于中高火险区，占比86.07%。3）研究区2001-2018年火点沿边境线分布，由南向北逐渐增多，火烧迹地面积2338.25 km²，国境线火烧频次集中在2~3次，中高火险区火点占比79.99%，风险区划精度较高。研究结果可对苏木政府制定草原火灾具体防灾减灾政策提供科学依据。