A novel approach to studying the effects of temperature on soil biogeochemistry using a thermal gradient bar

The temperature dependence of chemical reaction rates and microbial metabolism mean that temperature is a key factor regulating soil trace gas emissions and hydrochemistry. Here we evaluated a novel approach for studying the thermal response of soils, by examining the effects of temperature on gas emissions and hydrochemistry in (a) peat and (b) soil from a Sitka spruce plantation. A thermal gradient was applied along an aluminium bar, allowing soil to be incubated contemporaneously from 2 to 18 °C. The approach demonstrated clear differences in the biogeochemical responses of the two soil types to warming. The peat showed no significant emission of CH₄ at temperatures below 6 °C, while above 6 °C, a marked increase in the rate of release was apparent up to 15 °C (Q₁₀ = 2.5) with emissions being similar between 15 and 18 °C. Conversely, CH₄ emissions from the forest soil did not respond to warming. Nitrate availability in the peat decreased by 90% between 2 and 18 °C (P < 0.01), whereas concentrations in the forest soil did not respond. Sulphate availability in the peat decreased significantly with warming (60%, P < 0.01), while the forest soil showed the opposite response (a 30% increase, P < 0.01). Conventionally, thermal responses are studied by incubating individual soil samples at different temperatures, involving lengthy preparation and facilities to incubate samples at different temperatures simultaneously. Data collected on a given thermal response is usually limited and thus interpolated or extrapolated. The thermal gradient method overcomes these problems, is simple and flexible, and can be adapted for a wide range of sample types (not confined to soil). Such apparatus may prove useful in the optimization of management practices to mitigate the effects of climate change, as thermal responses will differ depending on land use and soil type.     

Prospective analysis for community participation in trypanosomosis control in The Gambia

The shift towards community participation in the eradication of trypanosomosis calls for investigation the underlying incentive structure for individuals in the community to cooperate in the provision of various control methods. Survey data were used to assess patterns of the community’s demand for insecticide pour-ons and trypanocidal drugs and factors affecting individual} demand in The Gambia. The results show that insecticide pour-on is strongly preferred. Similarly, farmers revealed a preference for community-based provision scheme. Factors affecting an individual farmer’s decision to invest in either pour-on or trypanocidal drugs were highlighted. While there are many factors associated with farmer’s decisions to invest in trypanosomosis control methods and to participate in collective actions, the results indicate that farmers} are ready to anticipate complete privatization of veterinary services through community-based schemes.     

羊草草原群落初级生产力动态研究

在锡林郭勒盟南部羊草草原对群落初级生产力动态进行11年的定位研究,结果表明:群落地上生物量有着显著的波动,在11年中遇丰年3个、平年7个、欠年1个。群落地上生物量季节积累动态符合Compertz曲线B_t＝B_max·e^-ea-kt,其高峰值出现在返青后的125.2～162.7天。制约群落地上生物量波动的限制因素是水分条件。建立了群落地上生物量与水热因子关系的数学模型。根据这些规律作者对畜牧业生产提出了合理建议。     

Identification of lactic acid bacteria in the feces of dairy cows fed whole crop maize silage to assess the survival of silage bacteria in the gut

In order to assess the survival of lactic acid bacteria (LAB) in whole crop maize silage in the gut of dairy cows, one representative silage sample and three different feces samples were collected from dairy cows on three dairy farms in Hua Bei, China and three dairy farms in Kyushu, Japan. The composition of the bacterial community was examined by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction. Lactobacillus acetotolerans was detected in all bunker‐made maize silage samples, regardless of the dairy farm or sampling region from which they were sourced. A total of eight LAB species were detected in the maize silage samples, of which three (L. acetotolerans, L. pontis and L. casei) appeared to survive digestion. The populations of L. acetotolerans in silage and feces were 10^6–7 and 10^3–4 copies/g, respectively, indicating that, even for the LAB species showing potential survival in the gut, competition in this niche may be harsh and the population may substantially decrease during the digestion process. It may be difficult for silage LAB to survive in the gut of silage‐fed dairy cows, because marked decrease in population can take place during the digestion process, even for surviving species.     

呼伦贝尔草甸草原群落特征对不同放牧制度的响应

对呼伦贝尔草甸草原划区轮牧和自由放牧两种放牧制度植物群落特征进行了比较研究.结果表明:羊草的密度在自由放牧区显著高于划区轮牧区,高度、盖度不同放牧处理之间差异不明显;贝加尔针茅高度和盖度轮牧区显著高于自由放牧区,密度对照区显著高于两放牧处理区;苔草高度、盖度和密度自由放牧区高于划区轮牧区.Margalef丰富度指数、S...     

施肥梯度对甘南高寒草甸植被特征的影响

通过小区控制施肥实验,研究了施肥梯度对青藏高原东缘高寒草甸植被特征的影响.结果表明,1) 施肥使线叶嵩草、波伐早熟禾、垂穗鹅观草等禾草的高度显著增加,异针茅、瑞玲草等非禾草类的高度减少.2) 随着施肥梯度的增大,群落的总密度逐渐下降, 禾草密度在不同施肥梯度下有时增加,有时减少,无一般性规律;而非禾草物种密度一般是减少的.3) 随施肥梯度的增加,地上生物量明显提高,多样性指数逐渐下降.施肥对群落密度、地上生物量和多样性的作用都要在2年以后才表现出明显的规律.     

甘南高寒草甸草原不同海拔土壤理化性质分析

对甘肃夏河高寒草甸不同海拔梯度的土壤理化性质分异规律进行了研究,以期探究土壤理化性质与海拔之间的关系。结果表明:除0~10cm土层电导率外,其余各土层土壤理化指标均与海拔呈显著相关(P0.05),其中,含水量、有机质含量均随海拔升高而升高,且随土壤深度增加而降低;pH随海拔升高呈先降低后升高的势态;0~10cm表层土壤全氮含量随海拔升高显著增加(P0.05),10~30cm土层全氮含量随海拔的升高先缓慢下降后平缓上升。因此,对于该区域草甸生态系统的管理与利用,不但考虑植被类型及状况,也需关注不同海拔梯度的草地土壤理化特性。     

钠离子对仔猪小肠刷状缘膜囊二肽跨膜转运的影响

为研究Na 在仔猪小肠Gly-Pro跨膜转运中的作用,采用同位素示踪及体外孵育技术,观察在不同Na 浓度梯度条件下Gly-Pro在仔猪小肠刷状缘膜囊(brush border membrane vesicles,BBMV)的跨膜转运量。结果表明:(1)用K 替代Na ,并没有降低Gly-Pro在BBMV中的转运量,在孵育前20min时间内,Gly-Pro的转运量稍稍提高;(2)Na 可使BBMV对L-丙氨酸的转运量提高到4.6倍,但不影响Gly-Pro的转运;二氢骆驼蓬碱显著地降低L-丙氨酸的转运,但对Gly-Pro的转运无影响。研究提示,Gly-Pro在仔猪小肠BBMV体系中的转运与Na 不存在依赖性的关系。     

扎龙国家级自然保护区水鸟群落季节性变化调查

对扎龙湿地的水鸟群落进行资源调查,共记录水禽52种,隶属于5目11科。其中古北界种类42种（占82％）,广布种类10种（占18％）,东洋界种类无记录。对结果进行分析发现：扎龙自然保护区水鸟群落种类和数量随着迁徙活动呈现了明显的季节性变化。春季水鸟迁徙时间集中,种群数量变化剧烈,有高峰期;秋季水鸟迁徙时间分散,种群数量变化缓和,无明显的高峰期。