气象条件对桂林沙糖桔产业的影响

桂林沙糖桔具有口感好,春节期间收获,市场销路好的特点,近年来得到了迅猛的发展.沙糖桔的产量及品质与气象条件密切相关,为研究气象条件对桂林沙糖桔的影响,分别对桂林各县种植沙糖桔地方的气候条件进行分析,对灾害性天气及其防御措施进行研究.沙糖桔适宜生长的温度为23～29℃,不耐涝也不耐旱,喜光照,不耐冰雪寒害.主要气象灾害有高温、低温、洪涝、干旱、大风、冰雹等.合理选择果园,科学管理,特别是要做好病虫害的管理,才能保证沙糖桔优质丰产.     

The impact of taxonomic change on conservation: Does it kill, can it save, or is it just irrelevant?

The important question of taxonomy and its impact on conservation efforts was brought to general attention by Robert May in 1990 with a News and Views article in Nature entitled “Taxonomy as destiny.” Taxonomy, however, has built-in instabilities that result in name changes, raising the question of whether name changes have a consistent impact on conservation efforts. Our review investigates three possible outcomes of taxonomic change, namely a positive impact on protection efforts, a hampering impact, or no measurable impact. We address these cases with a review of the relevant literature: specifically, government and conservation agency reports, scientific papers, and the general press, as well as correspondence with biologists active in plant and animal conservation. We found no evidence of a consistent effect of taxonomic change on conservation, although splitting taxa may tend to increase protection, and name changes may have the least effect where they concern charismatic organisms.     

Simulating site-specific impacts of climate change on soil erosion and surface hydrology in southern Loess Plateau of China

Proper spatial and temporal treatments of climate change scenarios projected by General Circulation Models (GCMs) are critical to accurate assessment of climatic impacts on natural resources and ecosystems. The objective of this study was to evaluate the site-specific impacts of climate change on soil erosion and surface hydrology at the Changwu station of Shaanxi, China using a new spatiotemporal downscaling method. The Water Erosion Prediction Project (WEPP) model and climate change scenarios projected by the U.K. Hadley Centre's GCM (HadCM3) under the A2, B2, and GGa emissions scenarios were used in this study. The monthly precipitation and temperature projections were downloaded for the periods of 1900–1999 and 2010–2039 for the grid box containing the Changwu station. Univariate transfer functions were derived by matching probability distributions between station-measured and GCM-projected monthly precipitation and temperature for the 1950–1999 period. The derived functions were used to spatially downscale the GCM monthly projections of 2010–2039 in the grid box to the Changwu station. The downscaled monthly data were further disaggregated to daily weather series using a stochastic weather generator (CLIGEN). The HadCM3 projected that average annual precipitation during 2010–2039 would increase by 4 to 18% at Changwu and that frequency and intensity of large storms would also increase. Under the conventional tillage, simulated percent increases during 2010–2039, compared with the present climate, would be 49–112% for runoff and 31–167% for soil loss. However, simulated soil losses under the conservation tillage during 2010–2039 would be reduced by 39–51% compared with those under the conventional tillage in the present climate. The considerable reduction in soil loss in the conservation tillage indicates the importance of adopting conservation tillage in the region to control soil erosion under climate change.     

抗生素对胃肠道微生态系的影响与对应举措

文章阐述抗生素对家畜胃肠道微生态系的影响与对应举措.凡进入家畜胃肠道的抗生素不仅可抑杀有害菌群、中性菌群,同时亦可抑杀有益菌群,破坏微生态系的生理组合等问题.提出了研发抗生素替代物的依据,指出中草药是理想的抗生素替代产品.     

Alternative silvicultural practices with variable retention improve bird conservation in managed South Patagonian forests

Alternative silvicultural approaches to timber management, such as regeneration treatments with different degrees of stand retention, may mitigate negative effects of clear-cutting or shelterwood cuts in forested ecosystems, including changes in old-growth forest bird communities. The aims of this work were: (a) to compare bird species richness and densities among different silvicultural designs with variable retention (dispersed and/or aggregated) and unmanaged primary forests, and (b) to assess temporal changes at community and species levels before and after treatments. A baseline avian survey was conducted prior to harvesting to evaluate canopy gap presence and forest stand site quality influences. Subsequent to harvesting, data on bird species richness and density were collected by point-count sampling during the summer season for 5 consecutive years (4 treatments × 5 years × 6 sampling points × 5 counts). Bird species richness and density (15 species and 9.2 individuals ha⁻¹) did not change significantly with forest site quality of the stands and canopy gap presence in unmanaged forests. However, both variables were significantly modified in managed forests, increasing over time to 18 species and reaching to 39 individuals ha⁻¹. Inside the aggregated retention, bird communities were more similar to unmanaged primary forests than those observed within the dispersed retention or in clear-cuts. Opting for a regeneration method with dispersed and aggregated retention has great potential for managing birds in Nothofagus pumilio forests. This method retained enough vegetation structure in a stand to permit the establishment of early successional birds (at least in dispersed retention), and to maintain the bird species of old-growth forests which could persisted in the retention aggregates.     

冲击条件对原木孔洞缺陷检测效果影响的研究

应用摆锤敲击装置,在实验室条件下研究冲击条件对原木内部孔洞缺陷检测效果的影响。摆锤冲击装置能以不同的速度敲击测试传感器,得到扰动信号在试样内的平均传播速度及原木孔洞缺陷区域的识别质量系数。研究结果表明,适当提高摆锤冲击速度,能够提高原木孔洞缺陷的检测效果。     

气候变化对福州植物气候生产力的影响分析

利用Thornthwaite Memoriae模型估算了福州市近30多年来的植物气候生产力的状况,在分析了年均气温、降水量、风速和相对湿度年际变化的基础上,探讨了植物气候生产力的变化原因。植物气候生产力与年均气温、风速成正比,故20世纪70年代后期和90年代后,受其影响,植物气候生产力在增大;植物气候生产力与年降水量和相对湿度成反比,所以20世纪70年代前期以及80年代,植物气候生产力在逐渐降低。     

国际金融危机下无锡旅游业的发展对策研究

分析了国际金融危机对无锡旅游业产生的负面影响,提出了加大投资、扩大内需、注重营销、企业联合、区域合作、稳定队伍、提升服务、政府帮扶等发展思路和措施。     

Review and analysis of documented patterns of agricultural research impacts in Southeast Asia

Based on a comprehensive search and review of the literature, 42 studies are identified for in-depth review and analysis of documented impacts of agricultural research from 1959 to 2009. This body of evidence is subjected to a systematic, quantitative scrutiny for the coverage and type of impact to derive patterns, gaps and trends in documented impacts of research in the subregion. The analysis offers compelling evidence that past investments in agricultural research in the region have been productive. In so doing, the study also reveals some persistent patterns and identifies a number of gaps between investments and documented impacts. Strikingly, the benefits are principally derived from rice improvement research, which has generated 86% of total documented benefits in the Southeast Asia region over the past five decades. In comparison with rice improvement research, evidence of impacts in other areas such as natural resource management and other commodities is minor. This suggests that there is considerably more certainty about the ability of rice research, particularly genetic improvement, to generate impact than is the case for other research foci.However, even for rice, the evidence has been patchy across time and space. There has been no comprehensive and subregion-wide attempt to inventory trends in adoption of improved rice varieties and document historical net benefits generated by this research effort. Despite the large-scale, long-term and sustained adoption of research generated rice technologies for smallholder farmers in this subregion, an impressive story on the impacts of agricultural research on long-term developmental goals still remains undocumented. The paper also reveals a declining trend in total documented net benefits from agricultural research in recent years, which is probably attributable to research lag times and changes in the intensity of impact assessment over time.     

2010年异常天气气候事件对呼伦贝尔岭西地区春小麦生产的影响

分析2010年作物生长季气象条件及其对呼伦贝尔岭西地区春小麦生产的影响。结果表明,春季低温、夏季干旱和阶段性异常高温等极端天气气候事件,是造成2010年该地区小麦大幅减产的主要原因。