城市拆迁空地对城市绿化率的影响   总被引：1，自引：0，他引：1  

邓理  郭松青  解清生  高丹  梁应仙 《水土保持研究》2006,13(3):244-246

近年来,我国城市建设发展迅速,产生了大量的拆迁空地,就拆迁空地对城市绿化率的影响进行了定量的研究,并提出相应的对策。  相似文献   

Relationship between wheat yield and Suaeda glauca coverage on fields with different soil Na concentrations in China     

NOBUMASA ICHIZEN  TAKAYOSHI NISHIO  JINGYU SUN  XIAOJING LIU 《Weed Biology and Management》2004,4(3):168-170

  相似文献   

近15年新疆伊犁河谷草地退化时空变化特征   总被引：1，自引：0，他引：1  

闫俊杰  刘海军  崔东  陈晨 《草业科学》2018,35(3):508-520

以伊犁河谷为研究区,利用MODIS NDVI数据及像元二分模型,反演草地植被覆盖度,以草地植被覆盖度为评价标准,结合数字高程模型(digital elevation model,DEM)数据及Getis-Ord Gi*冷/热点分析方法,对伊犁河谷2001-2015年草地退化的时空特征进行了分析。结果表明,1)受持续过度放牧及气候条件影响,2001-2015年伊犁河谷草地整体持续退化,15年内退化草地比例达46.18%,但退化以轻度为主;2)空间上退化草地的分布范围逐步向高海拔区域扩展,海拔1 500-3 000 m的中山和中高山区退化草地扩张最明显;3)草地生态保护政策的实施减缓了草地退化速度,草地退化与改善的空间差异逐渐明显,以退化为主的单一变化趋势有所改变;4)利用NDVI反演植被覆盖度对草地退化进行评价的方法存在对高植被覆盖区域草地退化敏感性相对较弱的缺陷。  相似文献   

The effect of orifice shape and the injection pressure on enhancement of the atomization process for pressure-swirl atomizers     

《Crop Protection》2016

The following paper presents results of studies on the atomization process of water in pressure-swirl atomizers with different shapes of orifice using a laser diffraction technique. The effect of the shape of the orifice and the injection pressure on the droplet size distributions and mean droplet diameters was analyzed. The results obtained showed that droplet size decreases with an increasing injection pressure and droplet size distributions are expanded. The smallest droplet diameters were obtained by atomization in profiled and conical shaped orifice atomizers, however the largest droplet diameters were achieved for plain orifice atomizers. The analysis of the interfacial surface produced by the atomizers has shown that the greater enhancement of the atomization process had occurred using profiled and conical shaped orifice atomizers compared with plain orifice atomizers. The correlation for the Sauter mean diameter as a function of the Reynolds number and the ratio of orifice length to diameter has been proposed. The paper is related to agricultural water management. The data obtained are important from the point of view of the design of atomizers, agricultural treatments and crop protection.  相似文献   

覆盖对红叶石楠和红豆杉生长的影响     

张金莎  王平  陈永安  舒东膂  胡勇 《湖南林业科技》2014,(5):63-64

在相同地域条件下,采用传统养护方式与覆盖养护方式的对比试验,研究覆盖对红叶石楠和红豆杉生长的影响。结果表明:合理有效的覆盖养护方式,可以明显的改良土壤肥力,促进植株生长。  相似文献   

基于TM NDVI的库尔勒市域植被覆盖动态变化   总被引：1，自引：0，他引：1  

蔡朝朝  安沙舟  蒲智  淮永建 《草业科学》2015,(7):1069-1078

以库尔勒市域为研究区,基于1990、1998、2006和2011共4期TM遥感影像提取归一化植被指数(NDVI),将NDVI结果输入到像元二分模型中计算得到研究区各时期植被覆盖度,然后根据研究需要将植被覆盖度划分为4个等级,最后计算覆盖度差值并结合各级覆盖度转移矩阵和土地利用情况分析了库尔勒市域植被覆盖度动态变化特征。结果表明,在1990、1998、2006和2011年间,库尔勒市域总体植被覆盖情况有所改善,植被恢复改善面积比退化面积多23.8%,其中东南部的扇形绿洲平原植被状况改善明显,北部和南部区域植被有所退化。  相似文献   

基于GF-1数据的南京江北新区植被覆盖度遥感估算     

高磊  卢刚 《安徽农业科学》2016,(10)

以南京江北新区为研究区,选用GF-1 16 m分辨率的MFV4多光谱传感器数据,基于像元二分模型对研究区进行植被覆盖度遥感估算。结果表明,GF-1数据可以快速有效地反映地表植被的空间分布状况。对结果的分级统计显示,江北新区植被覆盖较高,生态环境良好,适宜打造绿色宜居区域。  相似文献   

Assessing the deposition and canopy penetration of nozzles with different spray qualities in an oat (Avena sativa L.) canopy     

《Crop Protection》2016

Consistent spray coverage that is evenly distributed throughout the canopy is necessary to control pest populations that can negatively affect yield. As applicators are switching to Coarser spray quality nozzles to reduce risk and liability of pesticide spray drift, concerns about efficacy loss are growing. Previous research has indicated that small droplets are the most effective at penetrating through crop canopies, but newer nozzle technologies have improved the effectiveness of larger droplet or Coarser sprays. Research was conducted to assess the canopy penetration of nozzles that produce Coarse, Very-Coarse and Extremely-Coarse spray qualities compared to nozzles that produce Fine and Medium spray qualities. Kromekote collectors were positioned in four configurations in an oat (Avena sativa L.) var. ‘Yarran’ (AusWest Seeds, Forbes, NSW, Australia) crop to quantify the coverage and droplet number densities (droplets cm⁻²) across three application carrier volume rates: 50, 75 and 100 L ha⁻¹. Applications were made in the field in 30 cm tall, tillering oats, with collectors arranged in a randomised complete block design with three replications. The entire study was repeated on the following day. Results showed that droplet number densities were inversely related to the droplet size produced by the nozzles, yet coverage was increased more by application volume rate than droplet size. Thus, both spray drift reduction and improved canopy penetration can be achieved with proper nozzle selection and operation parameters for the control of agronomic pests.  相似文献   

3MG-30型果园弥雾机的研制与试验   总被引：7，自引：0，他引：7  

张晓辉  郭清南  李法德  李修渠  赵东 《农业机械学报》2002,33(3):30-33

研制了一种与小四轮拖拉机配套的、适用于标准化果园植保作业的机载果园型弥雾机，对该机各项性能指标进行了试验与分析。试验结果表明，与其他类型喷头相比，按一定排列组合的空心雾锥喷头在与风机配合使用进行药液的2次雾化时具有更好的喷雾量分布和雾滴分布均匀性；小于35m/s的风机出口风速所产生的梯度气流使枝叶扭转与退让，并使雾滴的穿透性和树内沉积量增加，提高了作业质量和机组生产率。  相似文献   

罩盖喷杆喷雾机的设计与防飘试验     

宋坚利  何雄奎  曾爱军  刘亚佳  张浩 《农业机械学报》2007,38(8):74-77

在机动背负式喷杆喷雾机的基础上设计了一台适合大田作业的手扶式罩盖喷杆喷雾机,分别进行了田间和室内防飘性能试验。结果表明,罩盖喷雾能增加雾滴在冠层中的穿透性,尤其使用小流量喷头时防飘效果更加明显。罩盖能够显著增加药液在喷头附近的沉积,减弱雾滴向下风向的运动能力,减少飘失。使用ST110-015型喷头,喷雾压力0.4MPa时罩盖的防飘效果最好。在相同风速下,罩盖对雾滴的防飘失效果不同,对较小雾滴的防飘失效果优于较大雾滴。  相似文献