闽南-台湾浅滩海域鱼类资源生产量

以海洋生态系统营养动力学为理论依据,根据调查所获得的有关闽南-台湾浅滩海域的初级生产力资料,检测了该海域的浮游植物有机碳含量,测算了生态效率,检测了52种主要经济鱼类营养级及其有机碳含量.采用营养动态模型和Cushing模型估算了该海域生态系统中鱼类资源的生产量(自然生产量),同时采用Cadima模式和MSY简单模式估算鱼类资源最大可持续开发量.估算结果如下鱼类资源生产量为98.63×104t,最大可持续开发量为 48.35×104t.1997年以来实际年渔获量为48.64×104t -53.83×104t,超过了鱼类资源的最大可持续开发量,呈现过度捕捞态势.还讨论了加强该渔场渔业资源管理的7项重要措施,以促进鱼类资源的较快恢复.     

烟单14号玉米产量构成模型及提高产量途径分析

根据1984—1986年烟单14号玉米田间试验的大量数据,作者在引进弹性系数概念后,建立了烟单14号夏玉米产量的非线性模型: Q=Ay~α_1y~β_2y~γ_3e~ε通过对模型中弹性系数的统计分析,提出大面积烟单14号玉米不同产量水平增产的途径,低产水平区(<250公斤/亩),着重提高亩穗数:中产水平区(250—400公斤/亩),在一定亩穗数的基础上,着重提高穗粒数;高产水平区(>400公斤/亩),提高粒重对产量的增产效益较大。     

A Review of Studies on the Interaction Between Waves and Muddy Bottom

This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University.     

A Quantitative Study of the Stony Coral Fishery in Cebu, Philippines

Abstract. The Philippines is generally accepted to be the center of the international trade of stony corals for ornamental use. Despite existing legal bans on the collection and export of stony corals in the Philippines, the coral trade continues to date, particularly in Cebu. This paper reports on the specific market demand for stony corals in Cebu and the effects of commercial collection based on the results of a quantitative study of two shallow coral reef areas subjected to large differences in collection effort. Comparison of the measured coral community parameters suggests selective population changes and reduced abundance of exploited coral populations as a result of commercial collection. Estimates of the natural mortality, fishing mortality and yield are presented for the two sampled populations of Pocillopora verrucosa , utilizing the method of GRIGG (1976). Based on the study results and a review of reported coral growth rates and coral colony size at reproductive maturity, the potential for resource management of stony corals on a sustainable yield basis is - discussed.     

Plants versus streams: Their groundwater-mediated competition at “El Morro,” a developing catchment in the dry plains of Argentina

Our understanding of how groundwater mediates evapotranspiration/streamflow partitioning is still fragmented and catchment studies under changing vegetation conditions can provide a useful frame for integration. We explored this partition in a flat sedimentary dry catchment in central Argentina in which the replacement of native vegetation with rainfed crops was accompanied by the abrupt formation of groundwater-fed streams by subsurface erosion (i.e., sapping) episodes. Historical records indicated widespread water table rises (~0.3 m y⁻¹ on average). Groundwater level and stream baseflow fluctuated seasonally with minima in the warm rainy season, indicating that evaporative discharge rather than rainfall shapes saturated flows. Diurnal groundwater level fluctuations showed that plant uptake was widespread where water tables are shallow (<3 m) but restricted to deep-rooted Prosopis forests where they are deep (7–10 m). MODIS and LANDSAT NDVI revealed a long-term greening for native vegetation, new wetlands included, but not for croplands, suggesting more limited evapotranspiration-groundwater level regulation under agriculture. Close to the deepest (20 m) and most active incisions, groundwater level and greenness declined and stream baseflow showed no seasonal fluctuations, hinting decoupling from evapotranspiration. Intense ecological and geomorphological transformations in this catchment exposed the interplay of five mechanisms governing evapotranspiration/streamflow partition including (a) unsaturated uptake and both (b) riparian and (c) distributed uptake from the saturated zone by plants, as well as (d) deepening incisions and (e) sediment deposits over riparian zones by streams. Acknowledging the complex interplay of these mechanisms with groundwater is crucial to predict and manage future hydrological changes in the dry plains of South America.     

Assessing crop yield and crop water productivity and optimizing irrigation scheduling of winter wheat and summer maize in the Haihe plain using SWAT model

Haihe plain is an important food production area in China, facing an increasing water shortage. The water used for agriculture accounts for about 70% of total water resources. Thus, it is critical to optimize the irrigation scheduling for saving water and increasing crop water productivity (CWP). This study first simulated crop yield and CWP for winter wheat and summer maize in historical scenario during 1961–2005 for Haihe plain using previously well‐established Soil and Water Assessment Tool model. Then, scenarios under historical irrigation (scenario 1) and sufficient irrigation (scenario 2) were, respectively, simulated both with sufficient fertilizer. The crop yield in scenario 2 was considered as the potential crop yield. The optimal irrigation scheduling with sufficient fertilizer (scenario 3) was explored by iteratively adjusting irrigation scheduling based on the scenario 1 and previous studies related to water stress on crop growth. Results showed that net irrigation amount was, respectively, reduced 23.1% and 18.8% in scenario 3 for winter wheat and summer maize when compared with scenario 1. The CWP was 12.1% and 8.2% higher with very slight change of crop yield. Using optimal irrigation scheduling could save 8.8 × 10⁸ m³ irrigation water and reduce about 16.3% groundwater over‐exploitation in winter wheat growth period. The corresponding yield was 18.5% and 12.9% less than potential yield for winter wheat and summer maize but using less irrigation water. Therefore, it could be considered that the optimal irrigation was reasonable, which provided beneficial suggestions for increasing efficiency of agricultural water use with sustainable crop yield in Haihe plain. Copyright © 2013 John Wiley & Sons, Ltd.     

Influence of aquifer properties and the spatial and temporal distribution of recharge and abstraction on sustainable yields in semi‐arid regions

This paper aims to contribute to understanding the importance of four factors on the determination of sustainable yields: (i) aquifer properties; (ii) temporal distribution of recharge; (iii) temporal distribution of groundwater pumping; and (iv) spatial distribution of pumping wells. It is important to comprehend how the present‐day and future vulnerability of groundwater systems to pumping activities depend on these critical factors and what the risks are of considering sustainable yield as a fixed percentage of mean annual recharge (MAR). A numerical model of the Querença–Silves aquifer in Portugal is used to develop hypothetical scenarios with which these factors are studied. Results demonstrate the aquifer properties, particularly the storage coefficient, have an important role in determining the resilience of an aquifer and therefore to which degree it is dependent on the spatial and temporal distribution of abstraction and recharge, as well as the occurrence of extreme events. Sustainable yields are determined for the developed scenarios based on specific criteria rather than a fraction of MAR. Under simplified current recharge and abstraction conditions, the sustainable yield was determined at approximately 73% of MAR or 76 million m³. When considering a concentration of rainfall in time, as predicted by climate scenarios for the region, sustainable yield could drop to ca 70% of MAR. However, a more even distribution of pumping volumes throughout the year could increase this value. The location of the pumping wells is seen to affect the distribution of hydraulic heads in the aquifer, albeit without significant changes in sustainable yield. Copyright © 2011 John Wiley & Sons, Ltd.     

两种不同产量历史丰歉气象影响指数确定方法在农业气象产量预报中的对比研究

利用吉林省1980—2015年春玉米单产数据、50个气象站逐日气象资料,基于欧式距离和相关系数建立综合诊断指标,利用综合诊断指标研究分析预报年与历史年春玉米气象产量丰歉气象影响指数的关系,以此构建春玉米产量预报模型,对吉林省春玉米产量进行动态预报。产量预报模型对2003—2012年的预报试验结果表明,产量丰歉趋势ΔY的平均正确率均在60%以上,加权分析法的单产预报准确率除2009年外,均高于80.0%,且各时段的预报准确率均高于大概率法的。对2013—2015年吉林省春玉米产量的预报检验结果表明,加权分析法对产量丰歉趋势ΔY的预报结果稍好;加权分析法单产预报准确率几乎都在90.0%以上,普遍高于大概率法的。说明加权分析法建立的产量预报模型预报效果更好,可在业务上应用。