The potential and realized spread of wildfires across Canada

Given that they can burn for weeks or months, wildfires in temperate and boreal forests may become immense (eg., 10⁰ – 10⁴ km²). However, during the period within which a large fire is ‘active’, not all days experience weather that is conducive to fire spread; indeed most of the spread occurs on a small proportion (e.g., 1 – 15 days) of not necessarily consecutive days during the active period. This study examines and compares the Canada‐wide patterns in fire‐conducive weather (‘potential’ spread) and the spread that occurs on the ground (‘realized’ spread). Results show substantial variability in distributions of potential and realized spread days across Canada. Both potential and realized spread are higher in western than in eastern Canada; however, whereas potential spread generally decreases from south to north, there is no such pattern with realized spread. The realized‐to‐potential fire‐spread ratio is considerably higher in northern Canada than in the south, indicating that proportionally more fire‐conducive days translate into fire progression. An exploration of environmental correlates to spread show that there may be a few factors compensating for the lower potential spread in northern Canada: a greater proportion of coniferous (i.e., more flammable) vegetation, lesser human impacts (i.e., less fragmented landscapes), sufficient fire ignitions, and intense droughts. Because a linear relationship exists between the frequency distributions of potential spread days and realized spread days in a fire zone, it is possible to obtain one from the other using a simple conversion factor. Our methodology thus provides a means to estimate realized fire spread from weather‐based data in regions where fire databases are poor, which may improve our ability to predict future fire activity.     

Micrometeorological measurements over 3 years reveal differences in N2O emissions between annual and perennial crops

Perennial crops can deliver a wide range of ecosystem services compared to annual crops. Some of these benefits are achieved by lengthening the growing season, which increases the period of crop water and nutrient uptake, pointing to a potential role for perennial systems to mitigate soil nitrous oxide (N₂O) emissions. Employing a micrometeorological method, we tested this hypothesis in a 3‐year field experiment with a perennial grass‐legume mixture and an annual corn monoculture. Given that N₂O emissions are strongly dependent on the method of fertilizer application, two manure application options commonly used by farmers for each crop were studied: injection vs. broadcast application for the perennial; fall vs. spring application for the annual. Across the 3 years, lower N₂O emissions (P < 0.001) were measured for the perennial compared to the annual crop, even though annual N₂O emissions increased tenfold for the perennial after ploughing. The percentage of N₂O lost per unit of fertilizer applied was 3.7, 3.1 and 1.3 times higher for the annual for each consecutive year. Differences in soil organic matter due to the contrasting root systems of these crops are probably a major factor behind the N₂O reduction. We found that a specific manure management practice can lead to increases or reductions in annual N₂O emissions depending on environmental variables. The number of freeze‐thaw cycles during winter and the amount of rainfall after fertilization in spring were key factors. Therefore, general manure management recommendations should be avoided because interannual weather variability has the potential to determine if a specific practice is beneficial or detrimental. The lower N₂O emissions of perennial crops deserve further research attention and must be considered in future land‐use decisions. Increasing the proportion of perennial crops in agricultural landscapes may provide an overlooked opportunity to regulate N₂O emissions.     

不同天气类型下UV-B辐射对高山植物美丽风毛菊叶片PSII光化学效率的影响分析

以中国科学院海北高寒草甸试验站地区的美丽风毛菊(Saussurea superba)为材料, 通过短期滤除自然光谱中紫外线B (UV-B)辐射成分的途径, 研究了UV-B辐射对叶片光系统II (PSII)光化学效率的影响。不同天气的归纳分析表明, 随可见光辐射的降低, 暗适应3 min的PSII最大光化学量子效率(F_(v)/F_(m))显著升高; 与此同时PSII实际光化学量子效率(Φ_PSII)和光化学猝灭系数(q_P)也显著升高, 非光化学猝灭系数(NPQ)则显著降低。滤除UV-B辐射后, 3种典型天气类型下的F_(v)/F_(m)均略有升高趋势; 且Φ_PSII和q_P增加, 而NPQ略有降低趋势。量子效率的相对限制(L_(PFD))和PSII反应中心开放程度(q_L)的进一步分析表明, UV-B辐射能显著影响辅酶A还原状态, 对高山植物美丽风毛菊的光合机构具有负影响。综上可知, 自然光中的可见光辐射是影响PSII激发能捕获效率的重要因素, PSII反应中心的光化学效率和非光化学能量耗散主要受光和有效辐射的影响; 滤除UV-B成分能减缓PSII反应中心的光抑制程度。     

In situ adaptive response to climate and habitat quality variation: spatial and temporal variation in European badger (Meles meles) body weight

Variation in climatic and habitat conditions can affect populations through a variety of mechanisms, and these relationships can act at different temporal and spatial scales. Using post‐mortem badger body weight records from 15 878 individuals captured across the Republic of Ireland (7224 setts across ca. 15 000 km²; 2009–2012), we employed a hierarchical multilevel mixed model to evaluate the effects of climate (rainfall and temperature) and habitat quality (landscape suitability), while controlling for local abundance (unique badgers caught/sett/year). Body weight was affected strongly by temperature across a number of temporal scales (preceding month or season), with badgers being heavier if preceding temperatures (particularly during winter/spring) were warmer than the long‐term seasonal mean. There was less support for rainfall across different temporal scales, although badgers did exhibit heavier weights when greater rainfall occurred one or 2 months prior to capture. Badgers were also heavier in areas with higher landscape habitat quality, modulated by the number of individuals captured per sett, consistent with density‐dependent effects reducing weights. Overall, the mean badger body weight of culled individuals rose during the study period (2009–2012), more so for males than for females. With predicted increases in temperature, and rainfall, augmented by ongoing agricultural land conversion in this region, we project heavier individual badger body weights in the future. Increased body weight has been associated with higher fecundity, recruitment and survival rates in badgers, due to improved food availability and energetic budgets. We thus predict that climate change could increase the badger population across the Republic of Ireland. Nevertheless, we emphasize that, locally, populations could still be vulnerable to extreme weather variability coupled with detrimental agricultural practice, including population management.     

海洋微生物纤维素酶的研究进展及其应用

海洋极端酶因在极端环境中具有更高的酶活性及更好的稳定性,因而具有重要的理论价值和工业应用前景.随着海洋微生物极端酶的研究开发,海洋微生物纤维素酶的研究也逐渐受到学者们的关注,并取得了较大进展.综述迄今为止分离出的产纤维素酶的海洋微生物种群及其酶学特性,海洋微生物纤维素酶基因克隆与表达的国内外研究现状,分析海洋微生物纤维素酶潜在的应用价值及未来发展前景.     

微生物脂肪酶稳定性研究进展

脂肪酶广泛应用于食品、药物、生物燃料、诊断、生物修复、化学品、化妆品、清洁剂、饲料、皮革和生物传感器等工业领域,微生物脂肪酶是商品化脂肪酶的重要来源。高温、酸性、碱性和有机溶剂等恶劣的工业生产环境使得脂肪酶的进一步工业应用受到限制,获取稳定性好的脂肪酶成为打破这一限制的关键环节。本文重点对提高微生物脂肪酶稳定性的策略进行了综述:挖掘极端微生物脂肪酶资源;利用定向进化、理性设计和半理性设计等蛋白质工程策略改造脂肪酶;利用物理吸附、封装、共价结合和交联等酶的固定化技术提高脂肪酶的稳定性;利用物理/化学修饰、表面展示以及多种改良策略相结合提高脂肪酶的稳定性。结合作者前期对酶工程的研究发现,新型酶催化剂的获得应该基于明确的设计思路,结合多种改造方法,基于定向进化-理性设计、定向进化-半理性设计、蛋白质工程-酶的固定化、蛋白质工程-物理/化学修饰、酶的固定化-物理/化学修饰等组合改造,比单一的改造方法具有更高的效率。     

陕西长武玉米降水指数保险设计

天气指数保险能有效规避传统农业保险的弊端.本研究基于陕西长武长序列产量数据和气象数据,采用统计分析的方法进行种植面积、产量、单产、趋势产量、相对气象产量以及玉米生育期需供水的分析;采用基于损失的风险评估方法评价种植风险;采用基于Logistic模型的费率厘定方法进行纯费率厘定;根据降水指数和减产率的相关性,设计降水指数...     

Potential use of weather radar to study movements of wintering waterfowl

To protect and restore wintering waterfowl habitat, managers require knowledge of routine wintering waterfowl movements and habitat use. During preliminary screening of Doppler weather radar data we observed biological movements consistent with routine foraging flights of wintering waterfowl known to occur near Lacassine National Wildlife Refuge (NWR), Louisiana. During the winters of 2004–2005 and 2005–2006, we conducted field surveys to identify the source of the radar echoes emanating from Lacassine NWR. We compared field data to weather radar reflectivity data. Spatial and temporal patterns consistent with foraging flight movements appeared in weather radar data on all dates of field surveys. Dabbling ducks were the dominant taxa flying within the radar beam during the foraging flight period. Using linear regression, we found a positive log-linear relationship between average radar reflectivity (Z) and number of birds detected over the study area (P < 0.001, r² = 0.62, n = 40). Ground observations and the statistically significant relationship between radar data and field data confirm that Doppler weather radar recorded the foraging flights of dabbling ducks. Weather radars may be effective tools for wintering waterfowl management because they provide broad-scale views of both diurnal and nocturnal movements. In addition, an extensive data archive enables the study of wintering waterfowl response to habitat loss, agricultural practices, wetland restoration, and other research questions that require multiple years of data. © 2011 The Wildlife Society.     

Thermal sensation prediction by soft computing methodology

Thermal comfort in open urban areas is very factor based on environmental point of view. Therefore it is need to fulfill demands for suitable thermal comfort during urban planning and design. Thermal comfort can be modeled based on climatic parameters and other factors. The factors are variables and they are changed throughout the year and days. Therefore there is need to establish an algorithm for thermal comfort prediction according to the input variables. The prediction results could be used for planning of time of usage of urban areas. Since it is very nonlinear task, in this investigation was applied soft computing methodology in order to predict the thermal comfort. The main goal was to apply extreme leaning machine (ELM) for forecasting of physiological equivalent temperature (PET) values. Temperature, pressure, wind speed and irradiance were used as inputs. The prediction results are compared with some benchmark models. Based on the results ELM can be used effectively in forecasting of PET.