Applying Local Measures of Spatial Heterogeneity to Landsat-TM Images for Predicting Wildfire Occurrence in Mediterranean Landscapes

In mountainous Mediterranean regions, land abandonment processes in past decades are hypothesized to trigger secondary vegetal succession and homogenization, which in recent years has increased the size of burned areas. We conducted an analysis of temporal changes in landscape vegetal spatial pattern over a 15-year period (1984–1998) in a rural area of 672.3 km² in Eastern Spain to investigate the relationship between local landscape heterogeneity and wildfire occurrence. Heterogeneity was analyzed from textural metrics derived from non-classified remote sensing data at several periods, and was related to wildfire history in the study area. Several neural network models found significant relationships between local spatial pattern and future fire occurrence. In this study, sensitivity analysis of the texture variables suggested that fire occurrence, estimated as probability of burning in the near future, increased where local homogeneity was higher.     

不同育秧方式对稻瘟病发生为害的影响

不同育秧方式对比试验的结果显示,秧田期在接种菌源条件下,旱育秧叶瘟较水育秧发生早、为害重;大田期在不防治条件下,旱育秧叶瘟、穗瘟发生为害显著轻于水育秧。说明在防止菌源进入的前提下,旱育秧是控制稻瘟病的一项好措施。     

稻田中华稻蝗发生动态、危害损失及防治指标

系统地研究了中华稻蝗发生动态与危害损失。结果表明,中华稻蝗在浙江年发生1代,主要危害早稻和早播单季晚稻。水稻分蘖期接入虫量10～50头/m2,叶被害率为52.61%～78.81%,叶被害指数为14.51～25.00,产量损失率为2.31%～27.42%,孕穗至破口期接入虫量1～17头/m2,叶被害率为56.63%～88.00%,叶被害指数为14.69～31.32,产量损失率为1.28%～32.74%,随着虫口密度增加,危害程度上升,产量损失率加大,两者具有密切相关性,建立了危害损失关系式。水稻叶片受害、光合能力减弱、幼穗分化不良、实粒减少、秕谷增加和粒重下降是导致水稻减产的主要原因。模拟测试表明,随着水稻受害生育期推迟损失增大,且分蘖期危害具有一定的补偿能力。在现有生产条件下,经济允许损失水平为2.5%～3.0%;2～3龄蝗蝻为防治适期,氟虫腈、三唑磷等有较好防治效果。提出水稻分蘖期和孕穗至破口期防治指标分别为10头/m2和5头/m2。     

农田黑线姬鼠发生规律与防治技术

１９８５￣１９９５年１０年监测结果表明,黑线姬鼠为浙江农田优势种,每年４￣５月和９￣１０月为繁殖高峰期,６月和１０￣１１月为数量高峰。冬前冬后密度基数,种群年龄结构,繁殖力,温度,降水,天敌和药剂防治是影响种群数量变动的主要因子及预测的依据。根据害鼠密度与稻麦为类损失率及经济允许水平,提出主害期控制的鼠密度指标为：大小麦２．７％￣４．４％,早稻４．６％￣６．７％,晚稻６．９％￣８．４％,防治指标为     

露地栽培番茄斑萎病毒病发生流行规律调查及TSWV重要寄主植物监测

为明确云南省昆明市露地栽培条件下番茄斑萎病毒病的发生流行特征,于2014—2015年采用病害系统调查法结合病毒ELISA及RT-PCR检测方法研究露地栽培条件下由番茄斑萎病毒(tomato spotted wilt virus,TSWV)引起的病毒病发生规律及其重要寄主种类,并研究利用防虫网隔离蓟马对番茄斑萎病毒病的防控效果。结果表明:番茄斑萎病毒病在露地番茄主要种植期3—10月普遍发生,番茄苗期和移栽初期是该病毒病防控的关键期,带毒种苗调运是该病毒病的主要传播途径;田间多种茄科和菊科植物是TSWV的重要中间寄主。在田间,菊科寄主植物油麦菜、莴苣、鬼针草、牛膝菊上TSWV的检出率均较高,在42.53%～81.63%之间;茄科寄主植物中辣椒上TSWV的检出率最高,为41.99%,其次为马铃薯,TSWV检出率为27.78%,在番茄上TSWV的检出率为19.02%,因此生产中应对这些TSWV重要中间寄主给予更多关注和防控。应用防虫网能有效隔离蓟马,使番茄斑萎病毒病发病率和病情指数较对照分别降低了6.44个百分点和5.31,可有效降低番茄苗期及定植期斑萎病毒病的发生。     

大兴安岭林区森工采运方式现状及发展趋势研究

本文论述了大兴安岭林区采运方式现状。分析了影响采运方式的因紊。提出了今后的发展方向。     

甘肃白水江林区落叶松球蚜红杉亚种发生及防治

落叶松球蚜红杉亚种以成虫和若虫群集在落叶松嫩枝、梢、针叶上吸食汁液。温度和湿度对红松球蚜的发生影响较大；相对湿度在58％-70％时，危害严重；相对湿度在75％以上时，落叶松球蚜数量减少；5月为发生危害高峰期。施药区相对防治效果可达92．4％。     

园林苗木穿孔病发病规律及综合防治技术

穿孔病是园林苗木的主要病害之一,大多数核果类苗木都是易感病品种,此病主要为害叶片,也为害嫩梢、枝干和果实,防治难度比较大。笔者借助显微镜,利用观察法对田间病菌孢子传播情况和田间病害发生情况进行测报分析,取得了测报结果,总结出了田间发病的始期、盛期和末期,制定了一套综合防治方法,并用于田间防治,取得了良好的防治效果。     

Selection of taxa as indicators of river and freshwater wetland quality in the UK

• 1. To assess the efficacy of environmental management policies and practices, there is a progressive transition from monitoring of activities towards assessment of their outcomes for the environment.
• 2. Population trends of key taxonomic groups can serve as useful indicators of broader environmental integrity and health. Several necessary and desirable criteria for selecting meaningful and suitable indicators are discussed. The attributes of a range of taxa and survey methods used for their assessment are discussed with reference to these criteria.
• 3. Survey methods, data holdings and analytical methods for populations of wild birds at present provide a good basis for developing indicators of the quality of fresh waters at a landscape scale. Other taxa are not necessarily any less appropriate; however, survey design and data representativeness are often limiting factors to the use of other taxa for assessing geographic and temporal trends.
• 4. Taxonomic science and ecological monitoring are necessary for determining society' progress with sustainable development and for informing appropriate enhancements to policy and management practice, particularly so for fresh waters.

Copyright © 2007 John Wiley & Sons, Ltd.     

Crunoecia irrorata (Curtis) (Trichoptera: Lepidostomatidae) and conservation of boreal springs: indications of clustering of red‐listed species

• 1. Crunoecia irrorata is widely dispersed across Europe, but rare and red‐listed in Finland. Its geographical range comprises most of the southern boreal zone in Fennoscandia. The species is confined to springs in the north, but occurs also in lower reaches of headwater streams in central and western Europe. It becomes more rare and less abundant towards the limits of its range across Europe, showing diffusive rarity. Glacial history and climate limit the distribution of the species in the north.
• 2. The most important habitat characteristic for C. irrorata in Finland was the total area of helocrene habitats. Its occurrence was positively related to taxon richness of benthic macroinvertebrates, but not bryophytes. Co‐occurrence of C. irrorata with other red‐listed spring‐dependent taxa was observed, indicating high conservation value of the springs occupied.
• 3. Crunoecia irrorata occurred frequently in moderately disturbed springs, indicating tolerance to human disturbance around springs. However, the effect of the disturbance on population size is not known. Forestry and water and gravel extraction are potential threats to C. irrorata, and only a few of its populations are strictly protected. Therefore, populations of C. irrorata in the boreal zone should be conserved and monitored to ensure the species' survival at the northern limits of its range.

Copyright © 2007 John Wiley & Sons, Ltd.