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61.
F.B. Lewu 《Biological conservation》2006,128(4):582-584
Pelargonium sidoides (Geraniaceae) is a medicinal plant used for the treatment of various infections including tuberculosis and bronchitis. Traditionally, only the roots of the plant are used for medicinal formulations in the Eastern Cape. In addition to traditional uses, there is a great demand for the plant for export, therefore, the rate of its harvesting and the number of its collector has increased in recent years. This has led to a drastic drop in the population of the species in the wild. A method that could achieve the sustainable harvesting of P. sidoides would be to substitute its shoot for the roots in medicinal formulations. A comparative study of the antibacterial activities of the leaves and the roots of the plant was conducted on the materials collected from three different populations. Generally, both the shoot and the roots of P. sidoides have antimicrobial properties. There was no significant observable difference between the MIC of extracts from both parts. The choice of the root by the traditional healers over the leaves may be arbitrary or due to easy collection. The leaves of P. sidoides may, as well, substitute for its roots in medicinal formulations especially in the treatment of bacterial diseases like tuberculosis and bronchitis. 相似文献
62.
In 1998 the protected population of Perameles gunnii (eastern barred bandicoot) at Woodlands Historic Park, Victoria, Australia became functionally extinct following removals of individuals for translocation between 1994 and 1996. Population viability analysis and data collected whilst the population was in decline are used to explore the impact that these removals had on the decline of the P. gunnii population at Woodlands. Due to some ambiguities in the life history of P. gunnii at Woodlands, two structurally different population models were used. Explicitly including the removal of animals in the analysis indicates that there may be at least a three-fold increase in the risk of quasiextinction due to removals. In some scenarios, over 17% of the trajectories decrease to a level less than or equal to 10 females within the observed time period of the collapse of the population, that is by April 1998. The modelling approach identified a number of critical factors in the decline of the population, such as variation in survival rates. By representing the life history strategy using two alternate models, quantitative statements about the impact that removals had on the population decline at Woodlands are made. While removals probably contributed to the collapse of the population, removals were not the sole cause of population decline. The real reasons for decline remain unknown; however, it is likely to be closely linked to habitat decline, difficult environmental conditions and predation. If P. gunnii are reintroduced to Woodlands again, then the models presented here may help to develop management strategies to establish a self sustaining population, as well as exploring translocations options. 相似文献
63.
红壤山丘综合开发治理试验研究杨端生(湖南衡山县水利水电局,421300)红壤主要发育于第四纪红土、红色砂岩、花岗岩、板页岩,海拔500m以下的低山、丘陵、岗地广泛分布。红壤士的共同特性是呈酸性反应,有机质较少,磷、氮偏缺;不同之处是发育于花岗岩、红砂... 相似文献
64.
65.
N.H. Batjes 《Soil Use and Management》2002,18(4):324-329
Abstract. Soil organic carbon and total nitrogen stocks are presented for Central and Eastern Europe. The study uses the soil geographic and attribute data held in a 1:2 500 000 scale Soil and Terrain (SOTER) database, covering Belarus, Bulgaria, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Moldova, Poland, Romania, the Russian Federation (west of the Urals), Slovakia, and Ukraine. Means and coefficients of variation for soil organic carbon and total nitrogen are presented for each major FAO soil grouping. The mean content of organic carbon, to a depth of 1 m, ranges from 3.9 kg C m–2 for coarse textured Arenosols to 72.9 kg C m–2 for poorly drained Histosols. Mean carbon content for the mineral soils, excluding Arenosols, is 15.8 kg C m–2 . The top 1 m of soil holds 110 Pg C (Pg=1015 g), which corresponds to about 7% of the global stock of soil organic carbon. About 44% of this carbon pool is held in the top 0.3 m of the soil, the layer that is most prone to be changed by changes in soil use and management. About 166 million ha in Central and Eastern Europe have been degraded by compaction, erosion of topsoil, fertility decline and crusting. The achievable level of carbon sequestration for these soils, upon adoption of 'best' management practices or restorative measures, is estimated. 相似文献
66.
67.
降水量对湖南省水稻生产的影响分析 总被引:2,自引:0,他引:2
根据1961-2010年湖南省自然灾害历史数据以及同期湖南省逐日降水量资料,利用一元回归、Mann-Kendall检验、Morlet小波分析等方法,对湖南省内1961-2010年的水稻受洪涝灾害及年降水量变化影响的特征进行了分析,在此基础上利用主成分回归方法,建立了湖南省水稻受洪涝灾害影响的多元回归方程.结果表明,湖南省水稻受洪涝灾害影响重、频率高,且在2000年后受灾的严重程度有加重的趋势;各降水因子中,暴雨日及大暴雨日产生的年降水量以及它们的雨日数是决定湖南省水稻受洪涝灾害影响程度的主要因子;利用时间、暴雨日的年降水量建立的多元回归方程可以简便地对某年湖南省水稻受洪涝灾害影响的程度进行简单的预测. 相似文献
68.
69.
湖南省茧蜂记述 总被引:5,自引:1,他引:4
按van Achterberg(1990)分类系统,报道了湖南省茧蜂15亚科38属104种,其中小腹茧蜂亚科的分类,按Mason(1981)分类系统处理。介绍了属名变动或种名定名的变化情况,并提出著者的看法。同时根据对湖南蝽茧蜂(Aridelus hunanensis You,Xiong et Zhou和橙足蝽茧蜂Aridelus rutilipes Papp雌雄外生殖器,以及对黄长柄茧蜂Streblocera flava You et Xiong和冈长柄茧蜂Streblocera okadai Watanabe雄性外生殖器研究,对陈学新和van Achterberg(1997)认为湖南蝽茧蜂是橙足蝽茧蜂的次定同物异名,黄长柄茧蜂和冈田长柄茧蜂是同种的看法提出了质疑。 相似文献
70.
章启辉 《湖南农业大学学报(自然科学版)》2000,(4)
湖南大学与岳麓书院一脉相承.湖南大学校史应从岳麓书院创建之年公元976年算起,历史上的各种文献资料早有志述,书院学制沿革、校史沿革等资料确凿可证,应以其千年历史沿革载入中国教育史册和世界教育史册. 相似文献