断裂构造地带公路定线研究

本文阐述在断裂构造地质地带的公路定线问题。包括:用航空象片判释和地质调绘方法查明断裂构造分布情况,用航测成图和纸上定线方法确定路基和桥隧构造物的稳定位置。结果表明:用航片判释区域地质构造有较好效果,通过地质调绘为评价路线方案和确定线位提供可靠依据,通过航测成图和纸上定线作出了比较经济合理的方案。     

湘西北美味牛肝菌的生态研究

美味牛肝菌菌体较大 ,菌肉肥厚 ,菌柄粗壮 ,食味浓香可口 ,属珍贵食用菌之一。不仅可食用 ,也可药用。本文就笔者 2 0 0 0年 5月以来 ,对湘西北美味牛肝菌的分布及生态研究的结果予以报告。     

贵州自然分布山茶属植物的资源现状

介绍了贵州省原生山茶属植物的自然分布及资源现状，共46种4变种。     

大别山-桐柏山地区杀虫性植物资源调查初报

大别山、桐柏山属于亚热带向暖温带过渡地气候 ,是植物区系的交接过渡地带 ,既有亚热带典型的代表型 ,又体现着过渡性的特征。能产生具有杀虫活性的次生代谢产物的植物即杀虫性植物。通过广泛调查、采集与鉴定 ,大别山—桐柏山地区分布有杀虫性植物 72科 138种     

中国梅的变异与分布研究

通过文献阅读、标本查阅及实地考察，发现了梅的一些变异类型。提出了梅的地理分布格局，对梅分布的历史迁作的探讨。种、滇、藏交界的横断山区是梅的自然分布中心，另外还有一些亚中心；在对种群数量和变异类型研究的基础上，确认梅的自然分布中心即梅的变异中心。     

研究森林变化对河川水沙影响的一种便捷方法──以四川省都江堰市白沙河为例

依据航片判读、森林资源调查资料和水文数据，利用流域自身对比法，得出森林变化对河川径流泥沙的定量关系。文中还阐明本方法的技术关键——消除降雨量不同对水沙的影响．该方法具有适合我国国情、费小效宏、精度较高、简捷易行等优点，值得推广提倡。     

中国的枸橼

枸橼在我国有11个类型(变种、品种或杂种),根据它们的地理分布和植物学性状,认为枸橼的原发中心在云南的西南部和西部;野生的沧源香橼是枸橼的原始类型,由其演化为小香橼、小果香橼和栽培的大香橼等;佛手是由枸橙演化而来。     

湖南省土地荒漠化和沙化监测布局与监测方法

我省土地荒漠化和沙化监测主要包括3个荒漠化监测站和5个沙化监测站，布设监测样地28个。确定了采集监测区域内气象、土壤、水文、生物等方面的信息和方法。     

An investigation of uncertainty in field habitat mapping and the implications for detecting land cover change

Land cover data for landscape ecological studies are frequently obtained by field survey. In the United Kingdom, temporally separated field surveys have been used to identify the locations and magnitudes of recent changes in land cover. However, such map data contain errors which may seriously hinder the identification of land cover change and the extent and locations of rare landscape features. This paper investigates the extent of the differences between two sets of maps derived from field surveys within the Northumberland National Park in 1991 and 1992. The method used in each survey was the Phase 1 approach of the Nature Conservancy Council of Great Britain. Differences between maps were greatest for the land cover types with the smallest areas. Overall spatial correspondence between maps was found to be only 44.4%. A maximum of 14.4% of the total area surveyed was found to have undergone genuine land cover change. The remaining discrepancies, equivalent to 41.2% of the total survey area, were attributed primarily to differences of land cover interpretation between surveyors (classification error). Differences in boundary locations (positional error) were also noted, but were found to be a relatively minor source of error. The implications for the detection of land cover change and habitat mapping are discussed.     

A seroepidemiological study on bluetongue virus in dairy cattle in the central valley of California

A seroepidemiological study on bluetongue virus (BTV) infection in California dairy cattle was conducted to estimate the prevalence and distribution by age and season of BTV group-reactive antibodies and to look for possible associations between the presence of antibodies and cattle age or breed and farm. Between December 1985 and March 1987, a sample of cattle was tested at approximately two-month intervals for BTV group-reactive antibodies using an enzyme-linked immunosorbent assay (ELISA). Data taken during the month of December 1986 were used to evaluate possible associations between a positive antibody test and certain intrinsic (age, breed) and extrinsic (farm) factors.Univariate and multivariate statistical analyses using the -square test for associations and multiple logistic regression, respectively, were carried out for possible associations between positive antibody tests to BTV and each factor of interest. The strengths of the associations were determined using estimates of the odds ratio.Of the 3774 serum samples tested, 238 (6.3%) were from calves, 1045 (27.6%) were from heifers and 2492 (66.0%) were from cows. Seroprevalence varied from nil in calves on two occasions to over 90% on several occasions in cows. Cows consistently had higher prevalence rates than heifers or calves across all test dates (p<0.05). The seroprevalence of BTV group-reactive antibodies also showed a seasonal fluctuation, with the highest rates occurring during the warmer months of the year. These highest prevalence rates coincided with heavy activity of the known vector of BTV, Culicoides spp. Breed and farm effects were not statistically significant (p>0.05). With the exception of one farm, all cattle were of the Holstein breed, which reduced confidence in assessing any breed effect in this study. Relative estimates of the sensitivity and specificity of BTV ELISA were 87% and 100% respectively, compared to the standard agar gel immunodiffusion (AGID) test.The observations support previous findings of seasonal distribution of BTV antibodies and suggest an age relationship, whereby older cattle are more likely to be positive to BTV group-reactive antibodies than younger cattle.