基于时空立方体的蒙古高原草原火高频区时空演变特征

蒙古高原东部草原火频繁发生，波及面广，对畜牧业发展威胁很大。本研究以蒙古高原草原火高频区2001-2020年的MCD64A1遥感火烧迹地数据为基础，利用时空立方体模型挖掘草原火的时空演变模式。结果表明：整体上，草原火从西南向东北逐渐增多，以国境线为界的火发生面积差异明显，主要分布在蒙古国境内，并存在明显的年际变化，每隔3～4年出现一次草原火发生的高峰。草原火高频集聚立方体的空间和时间自相关关系比较复杂，火事件的规律性差，不具有连续性，对防火防灾带来困难。草原火发生频率显著高或低的个别点主要分布在人口聚集的镇所在地；呼伦贝尔市东部、西部国境线附近，肯特省北部，东方省西南角、东北部、东南部以及与新巴尔虎左旗交界处草原火虽不连续发生，但近期发生频率较高，需要高度警惕。利用时空立方体挖掘蒙古高原草原火高频区时空演变模式，可为准确、快速识别草原火多发点位及其时空演变特性，网格化管理草原火，管护员巡查调度、草原火预测、降低火灾发生频率等提供辅助决策。     

草原可燃物动态研究

该项研究包括两个部分，即定位监测研究和路线抽样调查，定位监测研究是在容量发生草原火的典型草原区和草甸草原区以及黄土高原区选择具有代表性的典型地段，每年进行四次定位监测，取得草原可燃物量及其含水量以及土壤含水量在时间上的变化；路线抽样调查是在进入草原防火期（9月15日以后），草原可燃物量亦达到峰值期或翌年4月下旬草原可燃物量处于最低值时分别进行路线抽样实测，取得草原可燃物量及其含水量在空间的变化。通过进一步研究草原可燃物量及其含水量在时空的动态变化规律，为草原防火提供科学依据。     

锡林河流域中游草原植被退化遥感监测及合理放牧强度的确定

以内蒙古锡林河流域中游为研究区，应用Landsat TM资料，结合地面生物量定位测定，建立草原地上生物量估产模型，应用Visual C^ 编程，估算了2000年7月中下旬锡林河流域中部草原地上生物量。在锡林河流域中部两大草原植被类型[羊草 大针茅和(大针茅)克氏针茅 冰草]不同生物量的基础上，以象元为诊断单元，判别了各象元所代表地块草原植被的退化等级，绘制锡林河流域中部草原植被退化分布图。1999年锡林河以东草原退化面积为2697．3km^2，占中游草原面积的49．7％，以西退化面积为1644．4km^2，占30．3％。以草原生态系统可持续性为目标，针对不同退化等级草场制定不同的牧草产量利用率，划分6个放牧强度等级，计算各放牧等级的合理放牧得序(标捧羊单位／km^2)、面积和载畜量．研究结果可为草原退化的恢复、畜牧业的可持续发展提供决策支持。     

干旱荒漠区植被恢复动态遥感监测

摘要：植被盖度是评估区域生态环境的一个重要参数,本研究以1987、2003和2008年3期TM影像为基本信息源,通过NDVI植被指数估算植被盖度,对腾格里沙漠干旱荒漠区植被恢复效果进行定量动态分析。结果表明,1987-2008年研究区低盖度植被区面积逐步减少而高盖度植被区面积逐步增加,区域植被恢复效果明显;此外,通过对1987-2003年和2003-2008年两个阶段的植被盖度等级面积转化对比分析,区域内植被恢复的面积所占比率从1987-2003年的13.54%增加到2003-2008年的18.86%,表明植被恢复具后效性,其生态效益的发挥是一个逐步增强的过程。     

移动机器人定位技术研究综述

移动机器人的定位技术在机器人研究领域中已被广泛的研究,本文针对机器人的定位问题,基于绝对定位和相对定位两大类定位技术,对室内自主移动机器人的定位技术进行了综述,简述了基于地图匹配、路标识别、概率估算三种定位技术,以及各自的优势和局限性,并展望了移动机器人室内自定位技术的进一步研究方向。     

基于Landsat 8 OLI影像的渭-库绿洲植被地上生物量估算

干旱区绿洲植被地上生物量估算研究可为绿洲生态系统稳定性评价与区域碳储量估算提供重要依据。以渭干河-库车河三角洲绿洲为研究区，利用ENVI 5.3软件对Landsat 8 OLI 影像数据进行预处理，提取反映植被地上生物量信息的植被指数和波段因子，并结合样地实测数据，采用常规统计模型、多元逐步回归和偏最小二乘回归方法建立研究区植被地上生物量最优估测模型，从而揭示该绿洲植被地上生物量的空间分布特征。结果表明：1）所选的20个遥感因子与实测植被地上生物量呈极显著正相关关系，相关系数为0.5~0.7（P<0.01）。2）乔木与灌木地上生物量最优估测模型均为多元逐步回归模型，草本与农作物地上生物量的估测模型以偏最小二乘回归模型为最优，模型验证决定系数均在0.6以上，均方根误差和平均绝对误差均较小。3）研究区植被地上生物量主要在280~1450 g·m^-2 分布，面积约为6973.82 km²，低水平地上生物量（ABG<65 g·m^-2）分布区域约占研究区总面积的15.02%。地上生物量由高到低依次为：农作物>乔木>灌木>草本。根据不同的植被类型，基于地物光谱特征构建的遥感估测模型可准确估算干旱区绿洲植被地上生物量，并对其空间分布特征进行遥感定量反演。     

民用飞机短舱结构防火条款分析和符合性方法

短舱作为包裹发动机风扇火区和核心火区的结构,承担着防火墙的功能,其设计应满足防火条款的要求。本文通过对CCAR-25部短舱防火条款的分析,对其符合性方法进行了研究,提出了符合性设计与验证的思路,为短舱设计提供指导参考。     

肉鸡场的选址与规划

正1肉鸡场用地面积估算依据场内建筑物的面积(底层)占全场土地面积的百分数估算:肉鸡养殖场占地估算可用场内建筑物的总建筑面积(底层)占全场土地面积的百分数求得,一般商品场可按建筑物占全场面积的15%~25%来估算,肉种鸡场可按10%~15%估算。场内建筑物主要包括生产建筑、生活建筑和辅助建筑等。例如:已知某肉鸡场生产建筑、生活建筑和辅助建筑占地面积为6 000 m~2,该场的用地面积     

飞机发动机短舱防火墙结构和密封设计要求

短舱作为包裹发动机火区的结构,必须设计成能够将火区与非火区完全隔离,以避免火区的火焰进入到其他区域引起灾难性的后果。本文主要简述了短舱防火墙结构与防火密封件的设计要求和方法,重点介绍了防火密封件设计时要考虑的几大因素,为民用飞机发动机短舱的防火设计提供参考。     

一种基于轨迹数据的放牧强度估算方法

放牧强度直接影响草地生态系统的稳定和可持续发展。为指导牧民合理放牧以保证草畜平衡,笔者提出一种分布型放牧强度估算方法,首先对轨迹数据进行聚类分析,得到牲畜的不同觅食区域;然后估算各觅食区域的面积和区域内觅食羊只总数,得到各觅食区域放牧强度;最后对真实牲畜轨迹数据进行分析并估算苏尼特左旗某二牧区放牧强度,对放牧强度估算结果进行抽样和实地验证。结果表明:该方法能够有效估算不同觅食区域的放牧强度,明确区分不同过牧区域的过牧程度。     

浅议新形势下农村消防工作的现状及对策

当前农村人民群众消防安全意识普遍比较淡薄,消防基础设施缺乏,农村消防工作所面临严峻的形势。要改变当前农村消防工作应发挥政府职能建立健全消防安全组织网络;搞好农村消防规划,加强农村公共消防基础设施建设;深入开展消防宣传,提高村民的消防安全意识;强化公安派出所消防监督管理工作,夯实农村消防安全管理工作基石;突出重点,强化管理,全力维护农村消防工作稳定局面。     

中国草原火灾风险动态分布特征及管理对策研究

利用我国牧区1991～2005年的草原火灾资料,用统计方法分析了我国牧区草原火灾风险的时空动态分布特征.研究发现,随着经济的发展草原火灾的发生次数呈增长趋势,我国草原火灾风险正不断加大,草原火灾造成的损失也在逐年递增;每年的4月份是我国草原火灾的高峰期,10月份产生一个小高峰期;内蒙古、新疆、甘肃是我国草原火灾经济损失最严重的3个省份.针对我国目前草原防火减灾中出现的问题提出了管理对策.     

Fire as a Land Management Tool: Rural Sector Perceptions of Burn-off Practice in New Zealand

Fire has long been used as a tool to remove pests and disease, regenerate land, and remove unwanted vegetation buildup. Although traditionally used as a widespread land management tool in the past, its continued use could be under threat due to public perceptions pertaining to risks from burns getting out of control, as well as the impacts of smoke pollution and ecological damage. To determine the attitudes of rural practitioners and residents toward use of fire as a land management tool, this paper reports the results, analysis, and interpretation to a survey question: “Do you feel fire is a good option for managing rural land?”, along with an analysis of key attitudes toward the use of fire as a land management tool. The survey was undertaken with 696 respondents consisting of (rural land managers, rural populace, and rural fire personnel) within New Zealand. The survey identified differing perceptions about the suitability of prescribed fire use by land-based sectors. Five constructs explained the attitudes toward use of fire as a land management tool: benefits of fire use, the tradition of fire as a tool, regulations and liabilities, smoke impacts from fire, and the risks from knowledge loss and changing land use. Results showed that a person’s high agreement with the construct concerning negative smoke impacts resulted in less agreement that fire was a good option for use in rural land management in New Zealand. Main demographics influencing a positive attitude toward the use of fire included gender (male), their current use of fire, and larger land area managed. For prescribed fire to continue to be a useful tool, an improved understanding of current management practices and clear guidelines around best practice in using fire in New Zealand to manage land are required, with particular emphasis on limiting smoke impacts.     

Liability and Prescribed Fire: Perception and Reality

Changing climate and fuel accumulation are increasing wildfire risks across the western United States. This has led to calls for fire management reform, including the systematic use of prescribed fire. Although use of prescribed fire by private landowners in the southern Great Plains has increased during the past 30 yr, studies have determined that liability concerns are a major reason why many landowners do not use or promote the use of prescribed fire. Generally, perceptions of prescribed fire ? related liability are based on concerns over legal repercussions for escaped fire. This paper reviews the history and current legal liability standards used in the United States for prescribed fire, it examines how perceived and acceptable risk decisions about engagement in prescribed burning and other activities differ, and it presents unanticipated outcomes in two cases of prescribed fire insurance aimed at promoting the use of prescribed fire. We demonstrate that the empirical risk of liability from escaped fires is minimal (< 1%) and that other underlying factors may be leading to landowners’ exaggerated concerns of risk of liability when applying prescribed fire. We conclude that providing liability insurance may not be the most effective approach for increasing the use of prescribed fire by private landowners. Clearly differentiating the risks of applying prescribed fire from those of catastrophic wildfire damages, changing state statutes to reduce legal liability for escaped fire, and expanding landowner membership in prescribed burn associations may be more effective alternatives for attaining this goal. Fear of liability is a major deterrent to the use of prescribed fire; however, an evaluation of the risks from escaped fire does not support perceptions that using prescribed fire as a land management tool is risky. Prescribed burning associations and agencies that support land management improvement have an important role to play in spreading this message.     

Absence of a Grass/Fire Cycle in a Semiarid Grassland: Response to Prescribed Fire and Grazing

Many nonnative invasive grasses alter fire regimes to their own benefit and the detriment of native organisms. In southern Arizona the nonnative Lehmann lovegrass (Eragrostis lehmanniana Nees) dominates many semiarid grasslands where native grasses were abundant. Managers are wary of using prescribed fire in this fire-prone community partly due to the perceived effects of a grass/fire cycle. However, examples of the grass/fire cycle originate in ecosystems where native plants are less fire-tolerant than grasses and the invasive plant does not mimic the physiognomy of the native community. We investigate the effects of prescribed fire and livestock grazing on a semiarid grassland community dominated by a nonnative invasive grass. Lehmann lovegrass does not appear to alter the fire regime of semiarid grasslands to the detriment of native plants. Prescribed fire reduced the abundance of Lehmann lovegrass for 1 to 2 yr while increasing abundance of native grasses, herbaceous dicotyledons and fall richness, and diversity. Effects of livestock grazing were less transformative than the effects of fire in this long-grazed area, but grazing negatively affected native plants as did the combination of prescribed fire and livestock grazing. Although Lehmann lovegrass produces more fuel than native plants, fire frequency in semiarid grasslands appears to be limited by the paucity of above-average precipitation, which constrains high fuel loads. In addition, many native grasses tolerate high temperatures produced by Lehmann lovegrass fires. Consistent with previous research, fire does not promote the spread of Lehmann lovegrass, and more importantly human alteration of the fire regime is greater than the nominal effects of Lehmann lovegrass introduction on the fire regime.     

草原火研究综述

火作为重要的生态因子与我们的生活息息相关。国内外已对草原火展开了一定研究,本文讨论了草原火的研究成果,从影响因素、生态影响、时空分布格局、草原火的管理、遥感监控、预警和风险评价7个方面进行深入的探讨。一方面可为相关决策部门提供有力的科学依据,进而保证对草原火规范管理、草原生态环境平衡;另一方面,可为草原火发生发展过程,及其对相关区域乃至未来全球气候变化的影响研究提供依据,进而为当前全球变化研究做出贡献。由于目前在研究领域的局限性和研究时间间断性出现的问题,最后分析了草原火的研究趋势,并对火生态因子对全球气候变化影响和火灾预测模型有待深入的研究难点和发展趋势进行了展望。     

Seasonal Timing of Fire Alters Biomass and Species Composition of Northern Mixed Prairie

Fire plays a central role in influencing ecosystem patterns and processes. However, documentation of fire seasonality and plant community response is limited in semiarid grasslands. We evaluated aboveground biomass, cover, and frequency response to summer, fall, and spring fires and no fire on silty and clayey sites in semiarid, C₃-dominated grassland. The magnitude of change in biomass between years was greater than any differences among fire treatments. Still, differences existed among seasons of fire. Summer fire reduced non-native annual forb frequency (3% vs. 10% ± 2%) and Hesperostipa comata, reduced native annual forbs the first year, increased Poa secunda and bare ground, and increased Vulpia octoflora the second year. Fall fire increased grass biomass (1224 vs. 1058 ± 56 kg ? ha^? 1), but fall fire effects were generally similar to those of summer fire. Spring fire effects tended to be intermediate between no fire and summer and fall fire with the exception that spring fire was most detrimental to H. comata the first growing season and did not increase bare ground. All seasons of fire reduced litter, forb biomass, and frequency of Bromus japonicus and Artemisia spp., and they reduced H. comata, V. octoflora, and native annual forbs the first year, but increased basal cover of C₃ perennial grasses (2.2% vs. 0.6% ± 0.4%). Fire during any season increased dominance of native species compared with no fire (6.6% vs. 2.0% ± 1.0% basal cover) and maintained productivity. Seasonal timing of fire manipulated species composition, but increased C₃ perennial grass cover and native species dominance with fire during any season indicated that using fire was more important than the season in which it occurred. In addition, fire effects on the vegetation components tended to be counter to previously observed effects of grazing, suggesting fire and grazing may be complementary.     

Using Behavioral Change Models to Understand Private Landowner Perceptions of Prescribed Fire in North Dakota

In the northern Great Plains of North America, Kentucky bluegrass has become a conservation concern on many remaining rangelands. Reintroduction of fire may be one of the best ways to combat bluegrass invasion in the northern Great Plains, but perceptions of risk and other societal constraints currently limit its use. We mailed a self-administered questionnaire to 460 landowners in North Dakota to identify landowner attitudes and perceptions toward prescribed fire and understand major factors that limit the use of fire in rangeland management of this area. We draw from the theory of planned behavior and the transtheoretical model of behavior change, two widely used behavioral models, to better understand differences in motivations between ranchers and nonranchers and then formulate engagement actions conducive to a change in fire application behavior. Our results indicate that 55% of nonranchers and 38% of ranchers saw prescribed fire as a beneficial tool, with 25% of nonranchers and 9% of ranchers having performed a prescribed fire on their land. We therefore deduced these two groups were in different behavioral stages. Increasing understanding of the benefits of prescribed fire to forage quality and increasing overall acceptance of fire in North Dakota may be effective for ranchers, whereas approaches that address the lack of labor and equipment would be more applicable to nonranchers. Results also show that once respondents have decided to include the periodic use of prescribed fire as part of their management plans, there is a strong likelihood that they will perform a prescribed fire. On the basis of these findings, we propose that focusing on sociological factors influencing behavior of landowners can inform targeted strategies for increasing prescribed fire perceptions and application in the study area.     

Chihuahuan Desert Grassland Responds Similarly to Fall,Spring, and Summer Fires During Prolonged Drought

Land managers frequently use prescribed burning to help maintain grassland communities. Semiarid grassland dynamics following fire are linked to precipitation, with increasing soil moisture accelerating the rate of recovery. Prescribed fires are typically scheduled to follow natural fire regimes, but burning outside the natural fire season could be equally effective and more convenient for managers, depending on their management objectives. We conducted a field experiment in desert grassland to determine if fire seasonality influenced plant community recovery. Experimental burn treatments occurred in fall, spring, and summer in replicate 0.24-ha plots to determine if fire seasonality affected the rate of recovery of an ungrazed Chihuahuan Desert grassland in central New Mexico. Plant communities were surveyed seasonally for 5 yr after the burns. Grassland community structure responded to fire but not fire seasonality. Grass cover in all burned treatments remained lower than unburned controls for 3 yr after the burns. Community change through time was largely influenced by low rainfall, as grass cover in burned and unburned communities converged during a year with severe drought. In conclusion, fire seasonality did not influence rate of community recovery, but extended drought was possibly more influential than fire on grassland dynamics.