Seroprevalence of <Emphasis Type="Italic">Toxoplasma gondii</Emphasis> infection in yaks (<Emphasis Type="Italic">Bos grunniens</Emphasis>) in northwestern China

The seroprevalence of Toxoplasma gondii infection in yaks (Bos grunniens) was surveyed in Qinghai Province, northwestern China in May and June 2010. A total of 650 serum samples were collected from six counties and assayed for T. gondii antibodies by an indirect hemagglutination test. Antibodies to T. gondii were found in 35.08% (228/650) with the highest rate of 55.34% in Chengduo County. The results of the present survey indicated that infection with T. gondii in cattle is widely spread in China, including yaks in Qinghai Province.     

小麦抗麦茎蜂机制初步探讨

对青海、甘肃两地空心茎秆小麦抗麦茎蜂机制进行了初步研究。结果表明，断茎率与植株成熟时的株高、各节间长度、外径、干重呈正相关，与分蘖数，茎秆各节间实心负相关，抗虫小麦品系在麦茎蜂产卵期茎壁较厚，不利于麦茎蜂产卵；麦茎蜂幼虫取食时，茎秆内物质向其它部位运输，茎壁厚度下降至低于感虫品种，因而可能使幼虫所需营养物质的摄入量不足而使其生长发育受到影响。同时抗虫品系茎秆各部位养分较早向外运出，也可能对幼虫营养     

放牧强度和放牧时间对高寒混播草地牧草营养含量的影响

垂穗披碱草/星星草混播草地三个放牧季的牦牛放牧试验结果表明：放牧强度对牧草总能和粗灰分的影响极显著（P〈0.01）,对粗蛋白质、磷和中性洗涤纤维的影响显著（P〈0.05）,而对粗脂肪、粗纤维、钙和酸性洗涤纤维的影响不显著（P〉0.05）;放牧时间对粗蛋白质、粗纤维、钙、磷、中性和酸性洗涤纤维的影响极显著（P〈0.01）,对总能、粗脂肪和粗灰分的影响不显著（P〉0.05）;各放牧区牧草平均总能和磷含量之间呈极显著的负相关关系（P〈0.01）,与粗蛋白质和粗纤维之间呈显著负相关（P〈0.05）。     

Ecosystem Water Use Efficiency in a Semiarid Shrubland and Grassland Community

Ecosystem water use efficiency (EWUE) is defined as the net carbon uptake per amount of water lost from the ecosystem and is a useful measure of the functionality in semiarid shrub and grassland communities. C₄ grasses have higher water use efficiency (WUE) than do C₃ shrubs, although it has been postulated that C₄ plants have lost much of their advantage due to the rising atmospheric CO₂ concentrations. The hypothesis was that C₄-grass-dominated ecosystems have a higher EWUE than C₃-shrub-dominated ecosystems under the present CO₂ concentration and climatic variability. Evapotranspiration (ET) and CO₂ fluxes were measured with Bowen ratio systems at a shrub and grass site for 6 years in southeastern Arizona. Two different methods were used to evaluate growing season EWUE using the ET and CO₂ fluxes. The first method estimated a net daytime growing season EWUE for the grass site at 1.74 g CO₂ · mm^-1 ET and 1.28 g CO₂ · mm^-1 ET at the shrub site. The second method estimated maximum EWUE during part of the growing season at 7.35 g CO₂ · mm^-1 ET for the grass site and 4.68 g CO₂ · mm^-1 ET for the shrub site, which was considered a significant difference at P = 0.056. Data variability of the first method precluded a statistical difference determination between sites, but the results indicated that the grass-dominated ecosystem was between 1.4 and 1.6 times more water use efficient than the shrub-dominated ecosystem. Mean annual growing season precipitation and ET were similar in the two ecosystems, but the higher EWUE of the grassland system enabled it to take up more carbon during the growing season than the shrub ecosystem. Ecosystem differences in CO₂ and H₂O flux have important management implications including primary productivity, C sequestration, and rangeland health.     

人工种草治理"黑土滩"模式的构思与探讨

青海三江源地区的"黑土滩"面积已达490.90×104hm2,占三江源区草地面积的22.94%。总结业已实施的科研项目,分析以往治理"黑土滩"的经验教训和当前"黑土滩"治理中存在的问题,提出对坡度<7°、土层厚度≥30cm、≥0℃积温1000℃以上的重度"黑土滩"改建为人工饲草基地;对坡度<7°、土层厚度<30cm、≥0℃积温<1000℃的重度"黑土滩"改建为放牧型人工草地;对坡度在7~25°的中、重度"黑土滩"施以人工补播,改建为放牧型半人工草地的技术治理模式。同时,还提出了人工种草治理"黑土滩"的实施模式,其中心内容是成立以牧户为主体的生态保护和建设合作社,通过合同管理,实现种草、管理、利用各环节的协调运作,使国家生态建设投资效益最大化。     

青海高原近44年来气候变化的事实及其特征

利用青海省26个代表站1961-2004年逐月气温、降水量资料,给出了加权平均的气温、降水量标准序列,分析了青海近44年来气温、降水量变化特征.结果表明:青海气温变化趋势与同期全国气温变化趋势基本一致,气候存在着变暖的总趋势,年平均增温率为0.36 ℃/10 a,气候明显变暖的地区主要在北部,气候变暖主要是夜间气温明显上升所致,变暖的季节主要是冬季,青海高原气温变化的位相超前于全国气温的变化;青海高原降水量变化趋势的空间分布不一致,高原降水日数在减少,但降水强度在增大.     

灰翅麦茎蜂成虫羽化出茧规律

灰翅麦茎蜂(Cephus fumipennis Eversmann)是甘、青两省春小麦主要蛀茎害虫。近年来,麦茎蜂为害日趋严重,受害面积不断扩大,年损失小麦数千万kg。关于麦茎蜂的防治,国内主要采取成虫期药剂防治的方法。为了掌握最佳防治时期,提高药剂防治效果,作者对不同地区麦茎蜂成虫羽化出茧规律进行了研究。     

不同冷冻方法对GV期绵羊卵母细胞发育效果的影响

卵母细胞冷冻保存具有广泛而潜在的应用价值。文章主要分析了不同冷冻方法对绵羊GV期卵母细胞发育效果的影响。GV期卵母细胞程序化冷冻解冻后形态正常率（54.8%）和体外培养成熟率（14.7%）均显著或极显著低于细管玻璃化冷冻（71.8%,29.5%;P〈0.05）和OPS玻璃化冷冻（78.3%,P〈0.01;35.4%,P〈0.05）;3种不同方法冷冻GV期卵母细胞成熟率与对照组相比均差异极显著（P〈0.01）。     

三江源地区雪灾风险预警指标体系及风险管理研究

利用三江源地区越冬期雪灾历史资料及调查资料,深层次分析了诱发雪灾的孕灾环境、致灾因子与孕灾体,以进行风险辨识。确定了高寒牧区越冬期风险主要是由自然因素、生物因素、社会因素和管理等因素相互叠加后构成,从雪灾风险分析的角度构建了适合三江源地区越冬期风险预警指标体系,并采用定性与定量相结合的方法对各预警指标进行定量化与分级。在此基础上,结合畜牧业生产管理中的活动内容,将冬季风险管理分为：家畜管理、草地管理、饲草供应、草地资源评估、冬季风险预报,并分析了各种畜牧业生产活动在风险管理内容中的重要值。     

青藏铁路K1533路基风蚀防治措施效益研究

对青藏铁路K1533处高立式沙障和石方格沙障防风固沙的效益进行了研究,结果表明:高立式沙障可有效地降低防护区的风速,风速降幅范围在第1沙障后为14.63%~86.15%,第2沙障后为41.93%~97.91%,第3沙障后为22.80%~87.40%;同时降低了防护区的侵蚀量,高立式沙障后的侵蚀量和对照区相比,第1沙障后的侵蚀量仅占对照区的21.75%,第2,3沙障后的侵蚀量和对照区相比,其值缩小了数十倍到数百倍。石方格区的侵蚀量减幅更大,和对照区相比,相同高度的侵蚀量缩小了数十倍到数百倍甚至数千倍。高立式沙障、石方格沙障措施相结合使用,对于防治风蚀具有十分显著的作用,对保护风沙区铁路工程免遭风沙危害具有非常重要的作用。