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21.
为研究新生防制剂7.2亿CFU/g嘧泰多抗复合微生物菌剂对烟草靶斑病和野火病的防效,开展了不同药剂室内抑菌试验和田间药效试验。结果表明,7.2亿CFU/g嘧泰多抗复合微生物菌剂300倍液对烟草靶斑病病原菌和野火病病原菌的室内抑菌率均在60%以上;第3次药后,7.2亿CFU/g嘧泰多抗复合微生物菌剂300倍液对烟草靶斑病和野火病的田间防效均在65%以上,持效期长。7.2亿CFU/g嘧泰多抗复合微生物菌剂可作为兼防烟草靶斑病和野火病的推荐生防药剂。  相似文献   
22.
    
The most widely used metrics to characterize wildfire regime and estimate the impact of wildfires are total burnt area (BA) and the number of fire events (FE). However, these are insufficient to analyse the threat to society of a new fire regime characterized by a higher occurrence of very large events. To overcome this weakness, we propose the use of a Concentration Index (CIB) which makes it possible to identify spatio‐temporal patterns. The frequency distribution of BA follows a negative exponential distribution almost everywhere, in which a small minority of FE is responsible of the majority of BA. In this article, the spatio‐temporal behaviour of BA is analysed in Western Mediterranean Europe, with particular focus on Portugal, Spain, France and Italy, using data from the European Forest Fire Information System and national wildfire databases. This is the first time that the CI has been applied to wildfire events. This research shows that, in most Mediterranean European countries, the amount of BA is increasingly related with a lower number of fires. The spatio‐temporal distribution of CIB shows high variability in all of the countries analysed in Europe. Portugal and Spain show increasing significant trends of CIB + 7.6% (p‐value = 0.001) and + 1.3% per decade (p‐value = 0.003). Statistically significant correlations for Portugal, Spain and Italy are also found between the annual CIB and several teleconnection indices. The application of the CIB demonstrates its discriminatory ability, which is a key point in detecting vulnerable areas and temporal trends under climate change.  相似文献   
23.
Big sagebrush (Artemisia tridentata Nutt.) restoration is needed across vast areas, especially after large wildfires, to restore important ecosystem services. Sagebrush restoration success is inconsistent, with a high rate of seeding failures, particularly at lower elevations. Seed enhancement technologies may overcome limitations to restoration success. Seed pillows are one such technology designed to improve seed-soil contact in broadcast seedings by providing a favorable medium for seedling establishment and growth. Seed pillows have shown promising results in greenhouse studies; however, they have not been evaluated in the field. We compared broadcast-seeding seed pillows with broadcast-seeding bare seed in 2 yr across a large, burned elevation gradient. Compared with bare seed, we found no evidence that seed pillows improved sagebrush establishment and growth across the elevation gradient. Though our results suggest that seed pillows do not increase the likelihood of successful sagebrush restoration, they were successful at times when bare seeds were not, and the same was true for bare seeds. At least one of the two treatments was successful at 50% of the elevations over the 2 seeding yr. This suggests that a bet hedging approach, seeding both bare seed and seed pillows, may increase the probability of success. Further supporting the use of bet hedging, if both methods were used and seeding occurred in both years, success would have been 86%. Sagebrush density and cover varied by elevation. In the first-yr seeding, sagebrush density and cover generally increased with increasing elevation. In the second-yr seeding, sagebrush density and cover were greatest at the lowest and highest elevations. We speculate that at the lower elevations an unusually wet spring combined with limited herbaceous vegetation provided an ideal environment for sagebrush establishment and growth. Our results also demonstrate, counter to common assumptions, that lower elevations sagebrush seedings can be successful.  相似文献   
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25.
烟草野火病生理小种的研究进展   总被引:1,自引:1,他引:1  
 烟草野火病是世界普遍发生的一种主要侵染烟草的细菌性病害。从烟草野火病菌生理小种的鉴别方法,以及国内外关于烟草野火病菌生理小种的鉴别和分化方面的研究进展进行了描述,并对生理小种分化和鉴别研究存在的问题和展望进行了讨论。  相似文献   
26.
本实验对黑龙江省烟草叶片上引起退绿晕圈症状的病原细菌从形态学、培养性状、生理生化反应、抗菌素反应、抗血清反应及寄生范围等几方面进行了鉴定.结果表明:该菌为烟草野火病菌〔Pseudomonas syringae pv.tabaci(Wolf&Foster(1917)Young,Dye&Wilkie(1978)〕.试验菌株在细菌学性状等方面与已有的报道无显著差异,但在致病性(寄主范围)等方面则明显不同.本文还报道了该菌的几个新寄主.  相似文献   
27.
基于黑龙江省烟草野火病的状况,根据预警理论以及指标体系的优选原则,建立烟草野火病发生程度的警情、警源、警兆和警度指标的预警指标体系。利用时差相关分析法确定指标体系的先行、同步、滞后性质。利用反馈法确定警兆指标的警限区间以及警情的严重程度。应用确定的警情指标以及警兆指标的警限和警度构建黑龙江省烟草野火病预警的决策树模型,得到合理了决策树图谱,并对预警结果进行了相应的分析和有效性判别。为黑龙江省烟草野火病的预警提供相应的对策和建议。  相似文献   
28.
基于四川攀西地区2004—2020年防火期林火灾情数据和气象数据,对攀西林火的时间分布特征、空间分布规律、主要气候影响因子分布趋势与格局进行挖掘;利用ArcGIS格网法,结合双变量空间自相关分析方法,探讨气候影响因子对攀西林火发生的影响机制。结果表明: 2004—2020年攀西地区林火发生次数随时间发展呈现上升趋势,其中2004—2014年间,火灾次数和过火面积波动增加;2015—2020年火灾次数显著下降,但过火面积呈增加趋势,攀西地区林火主要发生在河谷盆地和丘陵地带,且多集中在丘陵的边缘地带。攀枝花市是林火频发区,凉山州次之。不同级别林火对不同时期气候影响因子的响应存在差异,火险期最高气温、降水、相对湿度及连续无降水日数的相关性显著,而非火险期连续无降水日数和平均风速的相关性较高,各气象要素与林火的逐月滞后相关也存在差异,表明前期气温、降水通过影响地面可燃物进而影响林火发生,持续性的干旱极有可能引发火灾。空间相关显示,林火次数与气温、蒸发、连续无雨日数的高高值主要分布在攀西地区的河谷盆地及丘陵区域,降水、相对湿度与林火的低高值聚集在北部的山原区,平均风速、干旱指数与林火的低高值和低低值聚集在西部山原区,表明攀西地区河谷盆地及丘陵区域的高温干旱使林火呈现聚集效应;而攀西区域南部的山地区,由于海拔较高,人为活动少火源较少,虽然是高温干旱区,也未出现林火聚集效应。  相似文献   
29.
    
Summary

The potential for severe impacts from a wildland fire, with or without a subsequent severe precipitation event, was evaluated in western and central Colorado and in a case-study area, the former Rio Grande National Forest (NF) of the San Juan-Rio Grande NF. The evaluation involved identifying the factors that are conducive to vulnerability and, additionally, the factors that impede or enhance recovery. Forest ecosystem characteristics that can increase vulnerability to the effects of a severe fire, with or without a subsequent severe precipitation event, include: relative flammability of forest floor materials, the location of nutrient storage (above or below ground), depth of soil, site quality, steepness of slopes, propensity to produce hydrophobic soils, and likelihood of mass movement, among others. Ponderosa pine forests appear more vulnerable, with natural regeneration more difficult than for some other types because of the relatively higher flammability of the foliar material in the forest floor, storage of nutrients above ground, and the episodic and infrequent years for good natural regeneration in drier areas.

In western and central Colorado, only two subbasins-the subbasin in which Boulder is located and the subbasin south of Denver-had both a high fire-ignition frequency and a high hydrophobicity composite risk index placing them at risk for both fire and erosional overland flow. Construction of a vegetation map showing the forest types most likely to be damaged by a severe wildfire and erosion, particularly on steep slopes, was done using GIS.

The forest landscape structure and composition existing today appear as the result of many stochastic factors operating over decades to centuries. Not all of these historic conditions and processes can be duplicated today. Potential losses of organic matter and nutrients from severe fire and subsequent intense precipitation events can be substantial.  相似文献   
30.
遥感可以提供燃料和其可燃性空间分布的信息,准确地了解燃料属性的时空动态,特别是空间分辨率高、覆盖范围大的燃料类型和燃料可燃性的遥感图像可以大大提高火险预报精度并有效地采取措施控制火燃烧的行为。本文通过文献综述,分析了应用卫星遥感技术监测林火燃料可燃性的国内外进展和未来发展趋势。  相似文献   
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