黄土丘陵区水土保持措施配置与土壤水分的关系

土壤水分与水土保持措施配置间存在密切关系,从空间结构看,地形起伏引起降水再分配,而工程措施可使降水形成有益的再分配,由此产生土壤水分的微域分异。这种分异制约影响着生物措施的空间配置;从时间过程看,为防止某些植物过度的水分消耗而致土壤干燥化,需采取循环轮作配置。在黄土丘陵区要求林草与农作物地在轮作周期内的总耗水量与有效雨量（降雨量与径流深之差）持平。     

黄土高原草地生产持续发展研究──Ⅰ．沙打旺人工草地衰退后的草种更替

沙打旺（Astragalus adsurgens）人工草地通常生长数年后即自然衰退。由于沙打旺具有强烈的土壤干燥化作用,在衰退草地上播种深根性豆科牧草生长不良;而播种的浅根禾本科牧草则生长正常,这就为衰退后草地的特续发展提供了人工更新草种,并为在不宜农作的土地上建立永久人工草地打下了基础。     

Arbitrary Curve-Based Methods in Ground Attributive Modelling

The basic concepts of ground attributes and Synthetic Digital Tarrain Model(SDTM) are introduced.An highly adaptable on_site realtime modeling method and on algorithms based arbitrary curves are suggested.The application of this method in high grade highway survey are introduced.     

Interannual variation of the diet shifts and their effects on the fatness and growth of age‐0 Pacific bluefin tuna (Thunnus orientalis) off the southwestern Pacific coast of Japan

We investigated the effect of feeding habits on the fatness (length–weight relationship (LW)) and otolith growth of age‐0 Pacific bluefin tuna (PBF) (fork length (FL) of 15.0–29.9 cm) collected off the southwestern Pacific coast of Japan from July to August during 2010–2015. The feeding rate on Clupeiformes (FRc) was substantially influenced by the path of the Kuroshio Current during early summer. We suggest that the following patterns occurred in the feeding habits of PBF. In 2012 and 2014, the short distance from the coast to the Kuroshio provided high overlap between PBF and Clupeiformes and increased the opportunity for feeding, and this pattern likely caused the observed diet shift from Crustacea to Clupeiformes by smaller PBF in the studied years than those in other years. In 2011 and 2015, the encounter probability for Clupeiformes might have been low due to the long distance to the Kuroshio Current, which led PBF to actively consume non‐Clupeiformes Teleostei. In contrast, in August 2010 and 2015, PBF did not encounter Clupeiformes or other Teleostei and may have been forced to feed on a large number of Crustacea; this effect was likely due to high water temperatures. Despite the interannual fluctuation in the timing of the diet shift and the feeding intensity (FI), these factors did not contribute to growth in length; rather, they contributed to fatness. Considering size‐dependent mortality in the larval stage, these results suggest that only fast‐growing individuals survive, even if the feeding conditions drastically change.     

茶园间作功能植物对茶小绿叶蝉的调控作用

为研究间作功能植物对茶园主要害虫茶小绿叶蝉的影响,于2017—2018年在福建省泉州市安溪县茶园间作白三叶Trifolium repens L.、金花菜Medicago hispida Gaertn.、金盏菊Calendula officinalis L.,以自然留养杂草茶园为对照,用网捕法采集茶小绿叶蝉并于室内计数,镜检剥查法调查其茶梢着卵量。结果表明,在4种不同生境管理茶园网捕茶小绿叶蝉总个体数及每月个体数均无显著差异;茶小绿叶蝉个体数分别在2017年8月与2018年6月达到高峰。茶梢各节间着卵量不同,主要产卵在顶芽之下第2～5节间,以第4节着卵量最多。间作金盏菊茶园茶小绿叶蝉在茶梢第1节着卵量显著高于间作白三叶和金花菜茶园。不同生境管理茶园茶小绿叶蝉在茶梢第4节着卵量从大到小依次为间作金盏菊(8.13)、间作金花菜(7.50)、自然留养杂草(7.17)和间作白三叶茶园(6.57)。不同时间段4种不同生境管理茶园茶小绿叶蝉在茶梢各节之间的着卵量存在差异,且均在9月上中旬着卵量达到高峰。在茶园间作功能植物,短期内未见其显著降低茶小绿叶蝉网捕量和茶梢着卵量的效应。     

自然环境中地面温度对亚洲小车蝗体温的影响

为了解白天地面温度对亚洲小车蝗体温的影响,2017年7月和2018年6-8月在内蒙古锡林郭勒盟的自然生境中6个地点开展了调查。结果表明:亚洲小车蝗的平均体温随地温变化,且在6:00-12:00和16:00-19:00内高于平均地温。地温与不同龄期和性别亚洲小车蝗体温之间呈极显著的非线性关系(P0.01)。体温只出现一次高峰,13:00左右的(39.3±0.2)℃;地温出现2次高峰,13:00左右的(42.0±0.5)℃和15:00左右的(38.9±0.4)℃。地温为31.5～38.3℃时,成虫的体温调节能力显著强于蝗蝻(P0.05);地温低于31.5℃和38.3～48.2℃时,蝗蝻的体温调节能力显著强于成虫(P0.05)。地温为26.1～40.0℃,雌虫的体温调节能力显著强于雄虫(P0.05);地温高于40.0℃,雄虫的体温调节能力显著强于雌虫(P0.05)。因此,地温可以作为监测该虫生长发育的因子为其防控提供依据。     

南亚热带丘陵赤红壤水分问题探讨

分析了南亚热带丘陵赤红壤区受气候因素的制约形成明显的湿季和旱季，阐述了季节性干旱、土壤水分特征因子和土壤物理性质退化导致的水分问题，提出了农业可持续发展的土壤水分调控生物或工程技术措施。如：农林复合生态系统的构建、减少地表径流、提高降雨入渗率、以肥调水、覆盖技术、人工保水措施、节水灌溉技术等。     

丘陵山地果园全液压遥控式履带动力底盘设计与试验

针对目前丘陵山地果园作业农用底盘整机体积大、行驶作业操作繁琐和通过性差等问题,结合丘陵山地果园开沟、除草和修剪等农艺管理环节的实际需求,设计了一款全液压遥控式履带动力底盘。首先,对动力底盘的整机结构和工作原理进行了阐述;其次,对前置挂载机构、行走系、变幅宽底盘、液压系统、遥控系统等关键部件进行设计和相应的匹配选型;最后,对整机进行了性能试验。试验结果表明：动力底盘在最小幅宽（1220mm）和最大幅宽(1620mm)的直线行驶偏移率分别为2.24％和2.2％,均满足相应国家标准（≤6%）要求。底盘的转向机动性能良好,最小幅宽原地转弯半径为905mm,可适应丘陵山地果园相对狭窄的坡地作业环境。遥控操作上下斜坡、翻越田埂、跨越畦沟等过程平稳,满足丘陵山地果园非结构化地形行走要求。挂载链式开沟器进行开沟作业时,沟深稳定系数为88.5%,沟宽稳定系数为92.5%,满足国家标准（≥85%）要求。整机工作性能满足丘陵果园复杂坡度地形管理作业要求,可为丘陵山地果园田间管理作业的有效实施提供综合应用平台和技术支撑。     

Response of soil microbial biomass and enzyme activities to the transient elevation of carbon dioxide in a semi-arid grassland

Although elevation of CO₂ has been reported to impact soil microbial functions, little information is available on the spatial and temporal variation of this effect. The objective of this study was to determine the microbial response in a northern Colorado shortgrass steppe to a 5-year elevation of atmospheric CO₂ as well as the reversibility of the microbial response during a period of several months after shutting off the CO₂ amendment. The experiment was comprised of nine experimental plots: three chambered plots maintained at ambient CO₂ levels of 360 μmol mol⁻¹ (ambient treatment), three chambered plots maintained at 720 μmol mol⁻¹ CO₂ (elevated treatment) and three unchambered plots of equal ground area used as controls to monitor the chamber effect.Elevated CO₂ induced mainly an increase of enzyme activities (protease, xylanase, invertase, alkaline phosphatase, arylsulfatase) in the upper 5 cm of the soil and did not change microbial biomass in the soil profile. Since rhizodeposition and newly formed roots enlarged the pool of easily available substrates mainly in the upper soil layers, enzyme regulation (production and activity) rather than shifts in microbial abundance was the driving factor for higher enzyme activities in the upper soil. Repeated soil sampling during the third to fifth year of the experiment revealed an enhancement of enzyme activities which varied in the range of 20-80%. Discriminant analysis including all microbiological properties revealed that the enzyme pattern in 1999 and 2000 was dominated by the CO₂ and chamber effect, while in 2001 the influence of elevated CO₂ increased and the chamber effect decreased.Although microbial biomass did not show any response to elevated CO₂ during the main experiment, a significant increase of soil microbial N was detected as a post-treatment effect probably due to lower nutrient (nitrogen) competition between microorganisms and plants in this N-limited ecosystem. Whereas most enzyme activities showed a significant post-CO₂ effect in spring 2002 (following the conclusion of CO₂ enrichment the previous autumn, 2001), selective depletion of substrates is speculated to be the cause for non-significant treatment effects of most enzyme activities later in summer and autumn, 2002. Therefore, additional belowground carbon input mainly entered the fast cycling carbon pool and contributed little to long-term carbon storage in the semi-arid grassland.