Determining landscape extent for succession and disturbance simulation modeling

Dividing regions into manageable landscape units presents special problems in landscape ecology and land management. Ideally, a landscape should be large enough to capture a broad range of vegetation, environmental and disturbance dynamics, but small enough to be useful for focused management objectives. The purpose of this study was to determine the optimal landscape size to summarize ecological processes for two large land areas in the southwestern United States. We used a vegetation and disturbance dynamics model, LANDSUMv4, to simulate a set of nine scenarios involving systematically varied topography, map resolution, and model parameterizations of fire size and fire frequency. Spatial input data were supplied by the LANDscape FIRE Management Planning System (LANDFIRE) prototype project, an effort that will provide comprehensive and scientifically credible mid-scale data to support the National Fire Plan. We analyzed output from 2,000 year simulations to determine the thresholds of landscape condition based on the variability of burned area and dominant vegetation coverage. Results show that optimal landscape extent using burned area variability is approximately 100 km² depending on topography, map resolution, and model parameterization. Variability of dominant vegetation area is generally higher and the optimal landscape sizes are larger in comparison to those features determined from burned area. Using the LANDFIRE project as a case study, we determined landscape size and map resolution for a large mapping project, and showed that optimal landscape size depends upon geographical, ecological, and management context. This paper was written and prepared by U.S. Government employees on official time, and therefore is in the public domain and not subject to copyright. The use of trade or firm names in this paper is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.     

湘西州森林防火与气象条件关系

利用1950~1988、2005~2015年湘西州森林火灾相关资料,1960~2015年湘西州8县(市)气象观测站温度、湿度资料,采用线性和曼-肯德尔(MK)突变检验的分析方法,对湘西州森林防火与气象条件关系进行研究。通过研究得出气象条件和森林火灾关系非常紧密,每年的春冬季节是森林火灾的高发期;确定森林火险预报模型为I=D×4+(100-H)×0.4+T+F+r,将森林火险等级划分为五级;对湘西州森林防火预警预报系统进行研发,将森林防火气象预报预警模型与突发事件预警信息发布的业务充分融合。     

PN型木材阻燃防腐复合剂的研制

ＰＮ型木材用阻燃防腐复合剂是一种含有磷氮及防腐剂成分的浅绿色或无色透明液体，经该复合剂处理的木材试件，氧指数＞５０％。木垛法测定的结果是，当木材的复合剂吸收量达７０ｋｇ／ｍ３以上时，燃烧失重趋于稳定，失重率保持在２５％以下。４５°斜面燃烧法测定，复合剂处理材达难燃级水平。复合剂中含有２％的防腐剂时，真菌腐蚀后的试材重量损失率小于３％，能防止木材腐朽变质。复合剂处理材的部分力学性能、胶合、抗吸湿性稍有降低，但对油漆、金属腐蚀无影响。该复合剂适用于车辆木结构材及其他室内木材的处理。     

火因子对松嫩羊草草原植物多样性的影响

应用三种丰富度指数，四种多样性系数，五种均匀度指数，进行了不同火因子对羊草草原植物多样性影响的研究。结果得出，灰分刺激与去枯作用明显提高了物种均匀度，加热作用则提高了物种丰富度，火烧的综合作用使得物种多样性显著增加，辛普森多样性指数计算的结果与其他 指数的结果截然相反，不适于在此种情况下应用。     

化学除草剂对改培型生物防火林带土壤理化性质及防火效果的影响

以试点中的黑龙江省改培型生物防火林带阻隔系统工程为依托,以可燃物载量为指标,探讨了除草剂对改培型生物防火林带土壤理化性质及防火效果的影响。结果表明:施用除草剂(森草净)后,改培型生物防火林带阻隔体系可燃物载量大幅减少,可有效地阻隔地表火的蔓延,减缓高强度林火的蔓延速度,且3 a后该建带方法未对土壤物理性质产生显著影响。     

木质材料系列阻燃技术的研究

ＷＦＲ木质材料系列阻民括多功能系列阻燃剂诼阻燃型木材、胶合板、刨花析和中密度纤维板的生产工艺。ＷＦＲ系列阻燃剂阻燃效果好，流失性小，低毒、防腐。用ＷＦＲ生产的板材阻燃性能和物理力学性能好。人造板板材甲醛释放量低。     

试论火与兴安落叶松种子发芽条件的关系

兴安落叶松(Larix gmelinii)自然分布区大兴安岭的立地条件和种子发芽条件的特殊性,导致了兴安落叶松天然更新的特殊性。瘠薄的棕色针叶林土,生长季短、冬季漫长以及土壤表层较厚的死地被物层增加了天然更新的难度。然而兴安落叶松的天然更新效果却是令人满意的。兴安落叶松在母树林冠下更新良好,只是在某些林型如草类落叶松林的成熟林冠下更新不良;而在3—10年的择伐迹地和火烧迹地上平均每公顷有13500株幼树。大兴安岭地区兴安落叶松火烧迹地天然更新良好的奥秘何在?火灾后兴安落叶松的种子发芽条件如何?火灾在这方面的作用是什么?作者从天然更新的关键之一——种子     

新造林中的防火隔离带建设

新造林中防火隔离带分为天然防火隔离带;植物防火隔离带;防火林道,人工防火线等4种。在具体布设上则分为林中防火、林线防火、山脊防火、境界防火、铁路沿线、林区房屋隔离带6种。     

Evaluation of the fire endurance of mechanically graded timber in bending

AbstractThis study examined the performance of mechanically graded timber in bending when exposed to fire at various load ratios. The test specimens were 150 pieces, each with the dimensions of 60 × 120 × 3500mm. The modulus of elasticity (MOE) of 150 specimens was measured, and 60 among them were selected to formulate the prediction equation for MOE and modulus of rupture (MOR), which was used to predict the remaining 90 specimens. These were tested under fire exposure in bending using three-point loading at 11.1%, 16.7%, 33.3%, 66.7%, and 83.3% of the ultimate load. Using mechanically graded timber, which means acknowledging the actual strength of the bending member, permits fairly precise application to the targeted design load. This research confirmed that mechanically graded timber under fire exposure has the following tendencies: under the same load ratio, time to failure is independent of strength class, and, at any load ratio, the critical strength is dependent on the timber strength class. The obtained design bending strength under fire exposure using the reduced cross section method and the reduced strength method conformed to those calculated based on Eurocode 5. Following those findings, mechanically graded timber can be applied to obtain the design bending strength when taking into account the fire attack.     

ＦＲ—１、ＦＲ—２及ＰＦ树脂对木材阻燃、防腐、尺寸稳定等效果的研究

功能性改良药剂ＦＲ－１、ＦＲ－２及ＰＦ树脂处理马尾松、毛白杨后对木材阻燃、防腐、尺寸稳定及ＭＯＥ／ＭＯＲ的研究结果表明，ＦＲ－１处理的马尾松吸药量为３４．５kg/m^3时，氧指数可达６１％。ＦＲ－１处理的马尾松、毛白杨达到阻燃标准时，其用药理根据板材的厚度进行了初步确定，剂量范围为３０－９０kg/m^3。ＦＲ－１及ＦＲ－２在达到阻燃用药量的同时，处理后的马尾松、毛白杨耐腐试验的重量损失率小于或按拉１０％。ＦＲ－１处理的马尾松、毛白杨、吸药量分别为７５．６及９３．５kg/m^3时，吸水至饱和时，木材抗湿胀率（antiswelling ef-ficacy,ASE)分别为３０％、４６％；ＰＦ树脂处理的马尾松、毛白杨 、吸药量分别为７９．０％、６３．８kg/m^3时，ＡＳＥ分别为４６．２％、４１．４％。各处理对抗弯弹性模具（ＭＯＥ）影响为，ＦＲ－１处理的马尾松，ＭＯＥ差异不明显，ＦＲ－１处理的毛白杨，ＭＯＥ增加幅度为６．１％，ＰＦ树脂处理的马尾松，毛白杨、ＭＯＥ增加幅度分别为１０．６％及１７．９％。ＦＲ－１处理的马尾松、毛白杨对抗弯强度（ＭＯＲ）影响不明显。