荒漠草原不同放牧制度群落现存量与营养物质动态研究

在短花针茅荒漠草原，比较研究了不同放牧制度对群落现存量与营养物质动态的影响，结果表明，划区轮牧和对照区牧草现存量差异不明显，但高于自由放牧区。轮牧和对照区群落现存量变化呈先增加，然后又下降的动态规律，自由放牧植物现存量几乎一直呈下降趋势。与轮牧和对照区相比，自由放牧区牧草在生长初期粗蛋白质、粗灰分、磷的含量均较高，粗纤维含量较低，生长后期则相反。     

Societal expectations of livestock farming in relation to environmental effects in Europe

The potential environmental effects of livestock farming are mainly associated with intensification of poultry, pig and dairy cow production systems. The major impacts are mainly caused by housing of livestock, which can lead to air and water pollution associated with nitrogen and phosphorus emissions and losses from manure. European countries regulate the potential for these types of pollution through a number of mechanisms, which have received wide public acceptance. In grazing systems, nitrogen pollution, associated with the use of nitrogen fertilizer, is also the subject of legislation. Perhaps because of this regulatory approach, surveys of the public have found that human food quality and animal welfare are more important issues than effects on air and water quality when considering livestock systems.Variation in stocking rates of grazing ruminants can change the structure and composition of pastures with potential impacts on biodiversity and the production of methane, a greenhouse gas. In European countries, maximum stocking rates have been set to reduce these impacts. Surveys of the European public have suggested that they are willing to pay for the mitigation of these environmental effects but that they also value strongly the cultural component of grazed livestock systems. There are few underlying concepts about how society views the environmental impacts of livestock systems. These are used to conclude that current attitudes are likely to prevail in the next decade.     

Observations of Phytophthora spp. in Water Recirculation Systems in Commercial Hardy Ornamental Nursery Stock

Samples of water and sediment were taken from drains, reservoirs and wells from four commercial hardy ornamental nurseries with water recirculation systems. The samples were taken on seven different dates throughout a single year from August 1994 to July 1995. The samples were screened for Phytophthora species using five different methods: direct plating, three bait tests (using lupin seedlings, apples and Rhododendron leaves) and a DAS-ELISA (double-antibody sandwich enzyme-linked immunosorbent-assay) with two antisera. In the nurseries with old water recirculation systems, Phytophthora species were detected in the drains and in the reservoirs. In the nursery with a new recirculation system, the pathogens were only present in the drains. None of the water samples from wells in any of the nurseries were contaminated. Phytophthora species were present in the water as well as in the sediment samples from drains and reservoirs. They were detected in the water recirculation systems irrespective of the season. The number of isolates increased about sevenfold between late summer and spring. At least 12 different Phytophthora species were identified: some isolates were previously unrecorded species. The epidemiology of the pathogens in outdoor water recirculation systems as well as the importance of the results for commercial nurseries is discussed.     

优质肉鸡繁育体系的效益评估

近十多年来，我国优质肉鸡的生产方兴未艾，许多育种公司和科研院所不断推出新品系。为充分发挥新品系的遗传潜力，探求优质肉鸡最佳的繁育生产模式具有重要意义。由于不同的品系及其杂种后代在不同的性状上各有优缺点，很难用生产性能进行直接比较，而适合用育种规划的方法通过经济学指标进行评价。系统分析通过把生产系统抽象概念化并用数学手段模型化的方法，     

Challenges in developing and implementing a decision support systems (ETÇAP) in forest management planning: a case study in Honaz and Ibradı, Turkey

Decision support systems (DSSs) are indispensable tools in preparing a forest management plan for a better combination of multiple forest values. This study attempted to develop and explain a stand-based forest management DSS (Ecosystem-based multiple-use forest planning [ETÇAP]) comprising a traditional simulation, linear programming (LP), metaheuristics and geographic information system. The model consists of five submodels; traditional management approach to handle inventory data, an empirical growth and yield model, a simulation to conceptualize management actions, a LP technique to optimize resource allocation and a simulated annealing approach to directly create a spatially feasible harvest schedule. The ETÇAP model has been implemented in a comparative two case study areas; Denizli–Honaz and Akseki–Ibrad?. Both simulation and optimization models outperformed to the traditional management plan. The periodical change of growing stock, allowable cuts, carbon sequestration and water production are used as performance indicators. The results showed that more amount of wood could be harvested over time compared to traditional level of harvesting. It could be concluded that various management strategies allowed managers to stimulate more decision options for better outputs through intertemporal trade-offs of management interventions as the model provided tools to quantify forest dynamics over time and space. Challenges exist to establish the functional relationships between forest structure and values for better quantification and integration into the management plans.     

芦苇和白刺空间格局对青土湖生态输水的响应

石羊河尾闾湖——青土湖位于腾格里沙漠和巴丹吉林沙漠边缘,是阻隔两大沙漠合围的生态屏障。自2010年开始连续5年向青土湖进行生态输水并形成一定规模的水面,对促进区域植被恢复和保护民勤湖区绿洲具有重要的生态意义。本研究选用2008年、2010年、2011年、2012年、2013年、2014年的高分辨率遥感影像资料同时结合研究区的实地调查资料,对形成人工水面的面积和输水前后的芦苇(Phragmites australis)、白刺(Nitraria tangutorum)群落面积进行了统计分析和对比。结果表明,5年连续输水形成叠加效应,水面面积成倍增加,芦苇相对频度逐年增加和白刺相对频度逐年减少,芦苇群落(Form.P.australis)面积增加了8.43倍,临接水域和水域中的白刺群落(Form.N.tangutorum)消失,白刺面积减少了68.00%。人工输水促进了芦苇群落依水蔓延,镶嵌于水域成片分布;距水面50 m范围的白刺群落由连续成片成点状。输水促进了湿生植物生长,导致荒漠植物种退化。     

加强图书馆联合参考咨询系统的建设,促进文献资源的开发利用

本文简述了文献传递服务发展的基本过程,概括了联合参考咨询网服务模式与内容,对现阶段UCDRS存在的问题进行分析与探讨,提出了解决问题的方法及优化措施,积极整合各类图书馆信息资源和服务力量,促进公益性联合参考咨询系统的发展。     

Soil enzyme activities during the 2011 Texas record drought/heat wave and implications to biogeochemical cycling and organic matter dynamics

Extreme droughts and heat waves due to climate change may have permanent consequences on soil quality and functioning in agroecosystems. During November 2010 to August 2011, the Southern High Plains (SHP) region of Texas, U.S., a large cotton producing area, received only 39.6 mm of precipitation (vs. the historical avg. of 373 mm) and experienced the hottest summer since record keeping began in 1911. Several enzyme activities (EAs) important in biogeochemical cycling were evaluated in two soils (a loam and a sandy loam at 0–10 cm) with a management history of monoculture (continuous cotton) or rotation (cotton and sorghum or millet). Samplings occurred under the most extreme drought and heat conditions (July 2011), after precipitation resulted in a reduction in a drought severity index (March 2012), and 12 months after the initial sampling (July 2012; loam only). Eight out of ten EAs, were significantly higher in July 2011 compared to March 2012 for some combinations of soil type and management history. Among these eight EAs, enzymes key to C (β-glucosidase, β-glucosaminidase) and P cycling (phosphodiesterase, acid and alkaline phosphatases) were significantly higher (19–79%) in July 2011 than in March 2012 for both management histories regardless of the soil type (P > 0.05). When comparing all sampling times, the activities of alkaline phosphatase, aspartase and urease (rotation only) showed this trend: July 2011 > March 2012 > July 2012. Activities of phosphodiesterase, acid phosphatase, α-galactosidase, β-glucosidase and β-glucosaminidase were higher in July 2011 than July 2012 in at least one of the two management histories. Total C was reduced significantly from July 2011 to March 2012 in the rotation for both soils. Only the activities of arylsulfatase (avg. 36%) and asparaginase showed an increase from July 2011 to March 2012 for both soil types, which may indicate they have a different origin/location than the other enzymes. EAs continued to be a fingerprint of the soil management history (i.e., higher EAs in the rotation than in monoculture) during the drought/heat wave. This study provided some of the first evidence of the adverse effects of a natural, extreme drought and heat wave on soil quality in agroecosystems as indicated by EAs involved in biogeochemical cycling.