球囊线蚓的发育起点温度和有效积温(环带纲:近孔目:线蚓科)

旨在探索严重危害西洋参幼苗的新害虫球囊线蚓Enchytraeus bulbosus(Clitellata:Plesiopora:Enchytraeidae)的生理学时间。在11.9、15.0、18.0、21.0、24.2、27.1、30.3、33.0℃恒温条件下培养球囊线蚓,测量卵期、幼蚓期、产卵前期及全代期的平均长度(N),纳入方差分析;再将N转换为倒数(V,V=1/N),以培养温度T对V做直线相关回归分析,由最小二乘法直接计算发育起点温度(C)和有效积温(K),建立发育历期对温度的倒数模型N=K/(T-C)。结果显示:卵期,r=0.996***,N=95.9/(T-6.1);幼蚓期,r=0.982***,N=96.2/(T-6.0);全代期,r=0.990***,N=238.4/(T-5.4)。C值和K值反映其生理生态学参数,并能在制定其综合治理方案时发挥积极作用。     

常德地区土壤水分自动站数据质量控制的阈值确定

统计分析常德地区9个土壤水分自动站关于土壤体积含水量、土壤相对湿度、土壤重量含水率、土壤有效水分贮存量逐小时资料,得到各层土壤水分分布特征.根据9个站点地理环境以及四要素分布、变化特点,针对作物地段和固定地段两种不同自动站,分汛期和非汛期两时段得到适合当地条件的各层土壤水分阈值和质量控制方案.通过质量评估结果的分析,发现有必要分别对固定地段和作物地段站点进行质量控制.土壤水分自动站小时资料的质量控制方案具有很好的适用性.各个要素各层在汛期和非汛期时段可用率很高,均超过95％.     

玉米叶片“源”的高温胁迫阈值研究

为了明确玉米叶片“源”的高温胁迫温度阈值,采用盆栽试验,利用可精准控温（模拟大气温度变化）的人工气候室,以日最高温32℃为对照,分别设置日最高温34℃、36℃和38℃ 3个处理,于玉米拔节期进行持续10d的温度控制试验,比较叶片光合作用光反应和暗反应阶段对不同高温的响应,以及叶片气孔和叶绿体超微结构的变化。光反应阶段,38℃处理下的光系统Ⅱ最大光化学量子产量（F_v/F_m）和实际光化学量子产量Y（Ⅱ）与其他处理相比均显著降低,但胁迫解除后均恢复至正常水平,而其他3个处理无显著性差异;暗反应阶段,与对照相比,36℃和38℃处理的叶片净光合速率（P_n）均显著降低,胞间CO₂浓度（C_i）均显著升高,且38℃处理在胁迫解除后P_n未能恢复。透射电镜结果显示,在36℃和38℃处理下,叶绿体结构逐渐紊乱降解,脂质球体含量增加,淀粉粒合成减少。综上可知,对于玉米叶片“源”,日最高温的胁迫阈值是36℃,阈值附近的高温胁迫主要是限制光合作用的暗反应阶段。     

葡萄日灼病阈值温度及主要影响因子分析

 以8年生红地球葡萄为试材，从诱发葡萄果实日灼病发生的阈值温度（临界果面温度）研究入手，探索气温、光照、风速等对果面温度的影响。结果表明：果面高温是果实发生日灼的直接原因。在‘红地球’葡萄果实的快速生长期测得日灼病发生的阈值温度为42.0～42.8℃（平均值42.3℃）；遮阴下的果实突然暴露在阳光下，12min后果面温度可达到最大值；强烈的光照可产生较高的气温及较高的果面温度，是日灼病发生的最重要影响因素。在夏季晴天无风的中午，每1万lx的光照强度可使果面温度增高1℃左右；无风时果面温度显著高于风速1.5m﹒s^-1以上时。在3.0m﹒s^-1风速下6min内可使果面温度降至最低；在相同的光温条件下，较高的空气湿度更利于日灼的发生。     

兴安落叶松鞘蛾有效积温的研究

为了解兴安落叶松鞘蛾各不同发育阶段对环境温度变化的敏感性,进而为预测各虫期的出现时间提供理论依据。于1986年4月到1987年4月,在东北林业大学帽儿山实验林场,对该种害虫的有效积温进行了测定;又于1987年4月—1988年10月,对所得结果进行了验证,最后表明:1—3龄幼虫、4龄幼虫、蛹、成虫以及卵的发育起点温度分别是:4.52±0.34℃、7.66±1.65℃、12.7±0.49℃、13.67±0.18℃、13.76±1.04℃;它们的有效积温分别是:1298.15±34.35日度、61.42±21.34日度;59.99±9.87日度、13.97±1.09日度、43.07±10.25日度。     

13种果树对酸雨抗性的研究

研究了模拟酸雨对荔枝、龙眼、柑橘等13种南方果树的叶片伤害、新梢增长率、细胞膜透性及叶片叶绿素含量的影响。结果表明,模拟酸雨抑制果树的生长,对叶片产生可见伤害,细胞膜透性增加,叶绿素含量降低;不同果树对酸雨的抗性也与酸雨的pH相关,芒果、枇杷、黄皮对酸雨抗性较强;猕猴桃、李、青梅、番石榴对酸雨最敏感;pH3.0～4.0是大多数南方果树产生显性伤害阈值,pH4.0可作为隐性伤害阈值。     

Species Dynamics in Disturbed Landscapes: When does a Shifting Habitat Mosaic Enhance Connectivity?

Although landscape ecology emphasizes the effects of spatial pattern on ecological processes, most neutral models of species–habitat relationships have treated habitat as a static constraint. Do the working hypotheses derived from these models extend to real landscapes where disturbances create a shifting mosaic? A spatial landscape simulator incorporating vegetation dynamics and a metapopulation model was used to compare species in static and dynamic landscapes with identical habitat amounts and spatial patterns. The main drivers of vegetation dynamics were stand-replacing disturbances, followed by gradual change from early-successional to old-growth habitats. Species dynamics were based on a simple occupancy model, with dispersal simulated as a random walk. As the proportion of available habitat (p) decreased from 1.0, species occupancy generally declined more rapidly and reached extinction at higher habitat levels in dynamic than in static landscapes. However, habitat occupancy was sometimes actually higher in dynamic landscapes than in static landscapes with similar habitat amounts and patterns. This effect was most pronounced at intermediate amounts of habitat (p = 0.3?0.6) for mobile species that had high colonization rates, but were unable to cross non-habitat patches. Differences between static and dynamic landscapes were contingent upon the initial metapopulation size and the shapes of disturbances and the resulting habitat patterns. Overall, the results demonstrate that dispersal-limited species exhibit more pronounced critical behavior in dynamic landscapes than is predicted by simple neutral models based on static landscapes. Thus, caution should be exercised in extending generalizations derived from static landscape models to disturbance-driven landscape mosaics.     

Click and low-, middle-, and high-frequency toneburst stimulation of the canine cochlea

A method was developed to deliver tonebursts ranging in frequency from 1 to 32 kHz for frequency-specific assessment of the canine cochlea. Brainstem auditory-evoked responses (early latency responses, 0-10 ms) to a click (CS) and to 1-, 2-, 4-, 8-, 12-, 16-, 24-, and 32-kHz toneburst stimulations (TS) were compared at 80-dB sound pressure level stimulus (SPL) intensity in 10 adult dogs. All stimulations yielded a 5-7 positive wave pattern, with the exception of the 1-kHz TS, which evoked a frequency-following response (FFR). Thresholds were lowest for the CS and the 12- and 16-kHz TS. All individual peak latencies for TS were significantly (P < or = .05) longer than for CS. Peak I latencies were significantly (P < or = .05) shorter for the 12- and 16-kHz TS than for the other TS. Interpeak latencies I-V were significantly (P < or = .05) longer for the 4- to 32-kHz TS than for CS. Differences in interpeak latencies I-III were not significant. Amplitudes of waves I and V were significantly (P < or = .05) lower for TS than for CS, except for higher wave V amplitude (P < or = .05) at 2- and 32-kHz TS. Peak I-V amplitude ratios were significantly (P < or = .05) higher for the 2-, 4-, 16-, 24-, and 32-kHz TS and lower for the 8- and 12-kHz TS, compared to CS. We conclude that reproducible information on frequency specificity of the canine cochlea can be obtained by TS. This report provides a normative database for parameters needed to evaluate frequency-specific hearing loss in dogs.     

杂交水稻黑条矮缩病发生为害损失与防治指标研究

根据1998-2003年杂交水稻黑条矮缩病发生为害损失与防治指标研究,测定了杂交水稻不同组合、不同生育期的发病率,以及秧苗期与大田期的侵染机率,分析了杂交水稻黑条矮缩病前后作发病率关系:M=1.6822m 0.1049,以及株发病率(M％)与产量损失率(Y％)的关系:Y=0.9776M-0.1935;阐述了灰飞虱不同虫量(X)与发病率和产量损失率(Y％)的关系:秧苗期为Y1=12.1841X1-1.0784,大田前期为Y2=4.5159X2-0.4620。在拟定经济允许损失水平的基础上,提出杂交水稻秧苗2-5叶期和大田初期为防治适期,并制定杂交水稻黑条矮缩病的策略性防治指标为前作穗期防治的黑条矮缩痛株发病率1.0％,制定秧苗期防治指标为带毒灰飞虱0.15只／0.11m2、大田初期防治指标为带毒灰飞虱4000只／667m2(百丛带毒灰飞虱20只)。经应用验证,与实际基本吻合。     

假眼小绿叶蝉防治指标的研究

利用网罩法测定了假眼小绿叶蝉不同虫口密度对茶鲜叶产量及受害指数的影响。在此基础上,建立了不同虫口密度与茶鲜叶经济损失率线性回归方程。根据目前茶叶的生产情况,制定了绿茶和乌龙茶不同茶区、茶季、茶鲜叶价格水平下假眼小绿叶蝉相应的防治指标。