饲料资源量概念及其判断

首先提出并讨论了饲料资源量的主体部分就是饲料能量总量及饲料蛋白质总量的问题。然后,用相关及回归方法筛选出了牛代谢能及粗蛋白质指标。在此基础上,建立了对饲料资源的品质和数量进行判断的蛋能结构指数及蛋能丰度指数体系。     

Abundance estimates of perch fry (Perca fluviatilis), complicated by grouped behaviour

Schnabel's mark and recapture abundance estimates of perch fry in Kli?ava Reservoir (Czech Republic), differentially marked in autumn and in spring, partly failed due to the existence of groups of individuals which behaved differently. There were three groupings. 1) a group of fry caught by shore seining from autumn of the first year (O+) to summer of the second year of life (1+), the only group in the littoral during late autumn and early spring and the fry with the slowest growth rate; 2) a group of perch fry that consisted of males maturing at 1 year and that dominated the trap catches in reservoir; 3) a group of fry that avoided the littoral in late autumn and during March-May 1983, which appeared in the littoral in May and June 1983, thus diluting the previously marked littoral fry. These 3 groupings of fry were relatively stable and separable throughout 1–2 years, apart for the mixing of groups 1 and 3 that took place in the littoral during the summer. The density of perch fry of 1982 year class in spring 1983 was estimated to be about 0.094 individuals per m².     

森林-草原交错带土壤节肢动物物种相对多度模型拟合研究

应用群落物种多度分布模型:对数级数分布模型、对数正态分布模型、几何级数分布模型和分割线段分布模型研究了森林草原交错带土壤节肢动物群落的种-多度分布关系。结果表明:对数级数分布模型和对数正态分布模型能够较好的拟合交错带大型土壤节肢动物群落的种-多度分布,中小型土壤节肢动物仅能用对数级数分布模型来拟合;几何级数分布模型和分割线段分布模型则不适于描述该区土壤节肢动物群落物种多样性。对数级数分布的参数α和对数正态分布的参数λ是反映群落结构特征内在性质的量,可以作为物种多样性指数运用,能较好地反映群落的物种丰富度。研究结果可为交错区群落物种多样性保护提供理论基础。     

黄陵县土壤养分丰缺指标和施肥指标体系制定

本文就黄陵玉米地土壤养分丰缺指标和施肥指标体系制定进行探究,目的在于对该区土壤养分进行评价,为当地农业生产提供新的施肥指标,为高产、高效、土壤培肥和农环保护提供相应理论指导。     

青海拉鸡山地区植物生物量及物种丰富度对海拔梯度变化的响应

以青海省海南州贵德县拉鸡山地区植物群落为研究对象,从海拔3100～3920m,划分为9个海拔梯度,研究了植物生物量及物种丰富度沿海拔梯度的变化特征。结果表明:阳坡地上生物量与物种丰富度呈极显著正相关关系(r=0.564,P<0.01),总生物量与根冠比呈极显著正相关关系(r=0.714,P<0.01);海拔与地上生物量呈极显著负相关关系(r=-0.773,P<0.01),与地下生物量、总生物量、根冠比呈极显著正相关关系(r=0.769、r=0.753、r=0.692,P<0.01)。阴坡植物群落总生物量与地上生物量之间呈显著正相关关系(r=0.495,P<0.05),与地下生物量之间成极显著正相关关系(r=0.960,P<0.01),与海拔呈极显著负相关(r=-0.519,P<0.01);根冠比与地上生物量呈极显著负相关关系(r=-0.631,P<0.01)。地上生物量与海拔呈极显著负相关(r=-0.678,P<0.01)。     

The Breeding Season of the Multimammate Mouse Praomys (Mastomys) Natalensis (A. Smith) in the Transvaal Highveld

Certain aquatic Oligochaeta live successfully in organic-polluted waters while others cannot tolerate such conditions. Tubifex tempUtoni Southern and Llmnodrttus hoffmeisteri (Clap.), two non-gilled species, are compared to Branchiura sowerbyi (Beddard) and Dero nivea (Aiyer), two gilled species, concerning their haemoglobin concentration, the influence of low oxygen availability on the respiration rate and their reactions in an oxygen gradient. In contrast with L. hoffmeisteri and T. templetoni where a very narrow range of respiration dependency (pO₂, 0-12 mm Hg) is found, B. sowerbyi and D. nivea have a level of respiratory dependence from pO₂, 0-131 mm Hg. Haemoglobin concentrations are 6,238 - and 6,452 g/100 cm² blood in L. hoffmeisteri and T. templetoni and 3,011 and 1,611 g/100 cm² in B. sowerbyi and D. nivea respectively. In the oxygen gradient all four species have a preference for water with a high oxygen content.     

A ram semen-collecting apparatus for mains or battery operation

Extract

This stimulator has been designed to be used by veterinary surgeons who require an instrument that is portable and can be used, not only on the A.C. mains, but also in the field, where power is not available. The number of controls has been kept to a minimum and the overall size and weight reduced to enable the stimulator to be included easily in the veterinarian's equipment bag.     

3种龙胆科植物的资源分配对策

选择青藏高原东缘同一生境类型下具有不同交配系统特点和不同传粉者丰度的3种龙胆科植物湿生扁蕾(Gentianopsis paludosa)(自花授粉)、祁连獐牙菜(Swertia przewalskii)(高昆虫访问异花授粉)和线叶龙胆(Gentiana farreri)(低昆虫访问异花授粉)为对象,研究其资源分配特征。结果表明,1)3种植物的花粉胚珠比例(P/O)存在显著差异(P0.05),湿生扁蕾的P/O显著低于另外两种异花授粉植物的(P0.05),祁连獐牙菜的P/O显著低于线叶龙胆的(P0.05);2)3种植物的繁殖分配比例存在差异,湿生扁蕾的繁殖分配比例显著高于另外两种异花授粉植物的(P0.05),线叶龙胆的繁殖分配比例显著高于祁连獐牙菜的(P0.05);3)在繁殖分配比例与个体大小关系上,湿生扁蕾与其个体大小不存在显著相关关系(P0.05),而另外两种异花授粉植物则与其各自个体大小之间存在显著负相关关系(P0.05)。研究表明,交配系统类型和传粉者丰度与植物的资源分配模式有关,尽管3种植物的繁殖绝对投入量都与其个体大小显著正相关(P0.05),但自花授粉植物相对于异花授粉植物具有较高的繁殖分配比例,并且这种较高的繁殖分配比例不受个体大小影响,这种高繁殖投入的资源分配模式可能与自花授粉植物具有繁殖保障,从而降低其繁殖代价有关。     

Rodent abundance triggered switch between the relative mutualism and predation in a rodent–seed system of the subtropical island forest

Density-dependent non-monotonic species interactions are important in maintaining ecosystem stability and function, but empirical evidences are still rare. Rodents, as both seed dispersers and seed predators, have dual effects on plant regeneration and may result in non-monotonic rodent-plant interactions. According to the non-monotonic models, the relative positive or negative effects of rodents on seedling establishment can be measured based on the positive or negative association of seedling recruitment rate and rodent abundance. In this study, we investigated the fates of acorns of Quercus serrata by tracking tagged seeds on 21 fragmented subtropical islands in the Thousand Island Lake, China. We found that the proportion of germinated seeds of all released seeds showed a dome-shaped association with rodent abundance per seed. The proportion of removed seeds and cached seeds showed a saturated- and a weak dome-shaped association with rodent abundance per seed, respectively. Our results demonstrated a clear empirical evidence that rodent abundance per seed triggered a switch between the relative mutualism and predation in a rodent–seed system. Our study implied that the observed non-monotonic interactions between plants and animals may play a significant role in maintaining biodiversity and ecosystem function. We appeal for more investigations of the complex non-monotonic interactions in various ecosystems.