规模化畜牧养殖对生态环境的破坏及防治

近年,畜牧养殖业蓬勃发展,过去的区域化散养已经基本不存在,养殖结构逐渐向集约化、一体化、规模化过渡,养殖规模也逐渐增大。养殖副产品肉、蛋、奶等极大满足了人们的生产生活,养殖中产生的尿液、粪污对生态环境造成极大影响。为促进规模化养殖实现绿色健康发展,该文分析规模化畜牧养殖对生态环境的破坏及防治措施。     

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。     

麻类纤维在非织造领域的应用

本文阐述了麻类纤维在我国非织造行业新用途的开发和拓展，对麻类纤维在非织造领域的利用符合国家农业可持续性发展的方向。     

An evaluation of the pesera soil erosion model and its application to a case study in Zakynthos, Greece

Abstract. The Pan‐European Soil Erosion Risk Assessment (pesera ) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha^?1 yr^?1 with a maximum error of 1.49 t ha^?1 yr^?1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7‐month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over‐riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha^?1 yr^?1, compared to a soil erosion rate of 0.04 t ha^?1 yr^?1, which can be tolerated for protecting the area for the sea turtle.     

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。     

超高产水稻产量形成的气候生态特点研究

在云南和湖南异地异季种植，研究了水稻超高产形成的相应气候生态条件，结果表明：超高产水稻具有大穗、多穗、高结实率的特点．云南试区具有日较差大、日照时数多、相对湿度低，平均温度较低的气候特点，故水稻生育期较长，同化物积累多，成穗率高，灌浆强度大．湖南试区阴雨寡照是影响产量的重要因素．     

Relating Kirtland's warbler population to changing landscape composition and structure

The population of male Kirtland's warbler (Dendroica kirtlandii) in the breeding season has averaged 206 from 1971 to 1987. The Kirtland's warbler occupies dense jack pine (Pinus banksiana) barrens from 5 to 23 years old and from 1.4 to 5.0 m high, formerly of wildfire origin. In 1984, 73% of the males censused were found in habitat naturally regenerated from wildfire or prescribed burning. The rest were in plantations (11%) or in harvested, unburned jack pine stands stocked by natural regeneration (16%). Twenty-two percent (630 of 2,886) of the Kirtland's warbler males counted in the annual censuses from 1971 through 1984 were found in 26 stands that were unburned and naturally regenerated following harvest. From 1982 to 1987, suitable regenerating areas were barely sufficient to replace currently occupied maturing stands, so population growth was impeded. Ecosystems of suitable size and regeneration characteristics (wildfire and plantation) doubled in area by 1989. In response, the population of Kirtland's warblers increased from 167 to 398 males between 1987 and 1992, but they withdrew almost entirely from the unburned, unplanted barrens by 1989 when the area of more suitable regeneration types increased. Minimum (368 males) and maximum (542 males) population estimates for 1996 were calculated based on 1984 average density (1.9 males per 40 ha) and peak population in burns (2.8 males per 40 ha).     

Landscape change under indirect effects of human use: the Savanna of Central Chile

The Chilean Intermediate Depression to the north of Santiago has experienced a physiognomical transformation from a Prosopis chilensis woodland to an Acacia caven savanna. Today P. chilensis trees are scarce and belong mostly to the larger size classes. By contrast A. caven seems to reproduce frequently and its populations consist of individuals of all size classes. In this paper we document these changes and report the results of tests aimed at determining the causes of these physiognomical changes. We found that livestock, leporids, introduced Mediterranean forbs and agriculture account for differences in seed dispersal and survival of A. caven and P. chilensis, which can explain the documented changes in the Chilean landscape.     

引起笼养蛋鸡疲劳症的主要因素研究

本试验以营养因子、产蛋率、钙源、笼养生态等角度对笼养蛋鸡疲劳症进行综合研究,寻找引起笼养蛋鸡疲劳症的主要因素及减少笼养蛋鸡疲劳症的途径。     

辽宁西部半干旱地区油松纯林改造的研究

喀左县位于辽宁西部地区，现存大面积油松人工纯林，不仅改善地力和水土保持效益差，而且火险性强、虫害蔓延成灾、生长早期衰退。为改善其林分生态条件，提高林木生长量和综合效益，在中三家镇对25年生油松人工纯林进行改造试验。结果表明，选择山杏、刺槐、沙棘等乔、灌木树种，利用林间空地、林缘隙地、侵蚀沟壑和疏林地造林，在大面积油松纯林连片地区进行窄带状或块状砍伐后造林，5年后效益显著，林分相对湿度提高了2．2％，土壤有机质含量提高5．4％，土壤含水量提高9．8％，减轻土壤容重３％,林分虫害明显下降，油松树高、胸径生长量分别提高22．6％、19．8％。