基于遥感指数的草原火后植被恢复研究     

宫大鹏  闫淳  郭赞权 《西北林学院学报》2021,36(6):204-210

草原火是草原生态系统重要的干扰因子，严重影响着系统的结构与功能。基于遥感数据，以2015年“4·16”特大草原火灾为例，利用ENVI和ArcGIS等软件，分别对NDVI和GPP指数及火烧严重度下的植被恢复过程进行定量分析。结果表明，基于NDVI和GPP指数的火后植被恢复过程表现相似，不同年份植被恢复情况存在一定差异。火灾发生当年（2015年）火烧迹地植被恢复状况高于未发生火灾区域，而在火后第1年（2016年）却又稍低于未发生火灾区域，直到火后第2年（2017年），火烧迹地植被基本恢复到火前状态。同时，不同火烧严重度下的植被恢复过程在存在明显差异。草原火灾发生后当年（2015年），中强度火烧下植被恢复最好，其次是轻度，重度表现最差。草原火烧严重度对植被恢复的影响，主要表现在火后第1个植被生长季。在之后的年份里，由于草原更新能力强大，不同火烧严重度对草原植被的影响不明显。本研究可丰富草原火灾及火烧迹地植被恢复等相关研究成果，同时为草原火灾管理和草原生态系统的可持续发展提供科学依据。  相似文献   

中文图书回溯建库中常见的书目数据质量问题及对策   总被引：2，自引：0，他引：2  

黄晓霞 《农业图书情报学刊》2004,15(3):91-93

本文对中文图书回溯建库过程中一些常见质量问题进行了举证说明 ,分析了产生错误的原因 ,并针对存在的问题提出了相应的对策 ,以确保书目数据的质量  相似文献   

论外来词     

张勇 《四川畜牧兽医学院学报》2005,3(3):112-114

随着科学技术的迅猛发展以及我国对外交往的日益频繁,外来词（借词）特别是英语词汇越来越多地渗透到我们的日常生活中.不少人对此表现出了很深的忧虑：这会不会破坏汉语文字的纯洁性？本文主要对外来词所涉及的内容、存在的依据、借用的形式以及应用等方面进行探讨,并着重指出外来词不会影响汉语的纯洁性;相反,外来词的借入会不断地丰富我们的语言宝库,因此人们应该以一种更开放的心态来吸纳外来词.  相似文献   

群钻钻削精度试验     

王志安  胡仲勋 《湖南农业大学学报(自然科学版)》1996,23(4)

通过群钻钻头直径Ｄ，进给量ｆ和切削速度ｎ对孔径扩张量，圆度，孔中心线垂直度和直线度影响的试验，得出它们的变化规律。  相似文献   

An evaluation of the Olsen test as a measure of plant-available phosphorus in grassland soils derived from basalt parent material     

A.A.W. Bell  J.S. Bailey  R.V. Smith 《Soil Use and Management》2005,21(3):322-329

Abstract. Anecdotal and circumstantial evidence have suggested that the Olsen test underestimates plant-available phosphorus (P) in basaltic soils in Northern Ireland. Therefore, the ability of this test to predict plant-available P in basaltic (and non-basaltic) soils was investigated by regressing Olsen-P data against herbage P indices calculated from plant tissue test data using the diagnosis and recommendation integrated system. The average Olsen-P concentration for a range of fields situated on basaltic soils was considerably lower than the average Olsen-P concentration for a range of fields situated on non-basaltic soils, and yet mean sward P status, as given by the herbage P indices, was similar for both groups of fields. Herbage P indices were also much better correlated with Olsen-P measurements in non-basaltic soils than in basaltic soils. Furthermore, at low Olsen-P values (≶9mgPL⁻¹) some swards on basaltic soils were genuinely deficient in P, while others were sufficient or even in surplus for this nutrient. The results confirm that Olsen-P is inadequate as a predictor of plant-available P in basaltic soils. It is concluded that an alternative soil test is needed to provide a reliable assessment of plant-available P in basaltic soils, to prevent overuse of fertilizer and manure P and to minimize the amounts of P entering local watercourses.  相似文献   

Evaluation of two N cycle models for the prediction of N mineralization from grassland soils in the UK     

A. Bhogal  A. Bhogal  M.A. Shepherd  D.J. Hatch  L. Brown  S.C. Jarvis 《Soil Use and Management》2001,17(3):163-172

Abstract. The ability of two nitrogen cycle models, of contrasting complexity, to predict N mineralization from a range of grassland soils in the UK, was evaluated. These were NCYCLE, a simple mass balance model of the N cycle in UK grasslands, and CENTURY, a more complex model simulating long-term C, N, P & S dynamics in grassland ecosystems. The models were tested using field measurements of net N mineralization from a range of grassland soils (differing in soil type, history & management practice), obtained over a 2 year period using a soil core incubation technique. This method was considered to measure the total net release of mineral N from the soil organic matter over a specified time, including N which may have been recycled several times. NCYCLE consistently under-estimated mineralization rates at all sites. By contrast, there was some correlation between CENTURY predictions of net N mineralization and field measurements. This may have reflected the different abilities of the two models to simulate N recycling. Neither model, however, was able to predict adequately the effect of cultivation and reseeding on net N mineralization.  相似文献   

马传染性贫血病病毒驴白细胞弱毒疫苗株前病毒全基因组核苷酸序列分析     

杨志彪  王柳  童光志  孔宪刚  仇华吉 《中国预防兽医学报》2001,23(3):161-166

  相似文献   

中西药结合预防肉鸡腹水综合征的临床试及防治机理探讨     

杨慧萍  岳治权  王建华 《中国家禽》2004,8(Z1):69-71

将一日龄艾维因肉仔鸡(雌雄各半)180只在同一舍内饲养,14日龄时将其随机分成4组,其中Ⅰ、Ⅱ组饲料按1％分别添加我们研制的方剂一和方剂二,连续用药15d,为药物预防组;Ⅲ组在饲料中按0.05％添加肾肿腹水消,连用7d(药品要求的预防剂量),为药物对照组;Ⅳ组饲料中不添加任何药物,为空白对照组。Ⅰ-Ⅳ组发病率分别为0、10％、3％和20％,42d时Ⅰ、Ⅳ组体重高于其它组,Ⅰ平均体重为1972.92g,Ⅳ组平均体重为1989.91g。试验表明方剂一为该试验条件下预防肉鸡腹水综合征最有效的方剂,其保护率可达100％,且不影响出栏重。对方剂一预防肉鸡腹水综合征的机理进行探讨。  相似文献   

《中国草地学报》2006-2008年载文及作者统计分析     

任丽平 《农业图书情报学刊》2009,21(11):79-81

通过对2006-2008年出版的《中国草地学报》载文及作者情况进行统计分析，研究其栽文和作者一些规律和特点。  相似文献   

八种中草药体外抑制大肠杆菌的效果观察   总被引：1，自引：0，他引：1  

黄雪泉 《贵州畜牧兽医》2009,33(1):3-4

选取马尾松、田基黄、艾草、雷公根、芭蕉芯、浮萍、野菊花、番石榴叶8种中草药，采用常规中草药药敏试验打孔法和试管法对猪大肠杆菌（K88）、大肠杆菌（0157）进行体外抑菌试验。结果显示，艾草、野菊花、番石榴叶对大肠杆菌呈高度敏感，其中艾草对大肠杆菌抑菌力最强；马尾松挥发油对大肠杆菌呈中度敏感；田基黄、雷公根、芭蕉芯、浮萍对大肠杆菌无抑菌作用。  相似文献