锡林郭勒草原蒸散发月季动态及相关因子分析

蒸散发(Evapotranspiration,ET)的时空动态对理解水热对植被的影响具有重要作用。利用MODIS MOD16A2和MOD13A3月产品数据及气象数据,通过回归分析和相关分析等方法,研究了锡林郭勒草原不同类型草地近15年(2000—2014年)的ET月季动态及相关因子。结果表明:3—10月的ET均表现出草甸草原典型草原和沙地植被荒漠草原,1—2月和11—12月的ET均表现出草甸草原典型草原和沙地植被荒漠草原。荒漠草原11月ET最大,其余各类草原均在7月达到最大值;各类草原的最小ET均为5月。各类草原3—5月和10月的ET均为下降趋势,而1月、6月、7月和12月的ET均为上升趋势。春季、夏季和秋季的ET均表现出草甸草原典型草原和沙地植被荒漠草原,而冬季的ET表现出草甸草原典型草原和沙地植被荒漠草原。荒漠草原冬季ET最大,其余各类草原的ET均在夏季达到最大值。各类草原春季和秋季的ET均为下降趋势,而夏季和冬季的ET均为上升趋势。Pearson相关分析表明3—10月及春季、夏季和秋季的ET与NDVI和降水量显著正相关,与平均气温显著负相关(p0.05);相反,1—2月、11—12月及冬季的ET与降水量负相关,而与平均气温显著正相关(p0.05)。     

Site-Specific Nitrogen Management in Rice Using Remote Sensing and Geostatistics

Proper doses of nitrogenous fertilizer are most important for rice production system because a large part of the nitrogen may be lost if it is not applied judiciously. A study was conducted covering five blocks of Balasore and two blocks of Bhadrak districts. Soil samples were collected randomly, and field visit was conducted during peak vegetative stage of rice. Two approaches have been used in this study for estimating the site-specific nitrogen (N) requirement in the study area. In one approach, geostatisical analysis and kriging was used to develop the soil test–based N recommendation map by which a minimum of 72 kg N ha^?1 and maximum of 94 kg N ha^?1 were recommended. In a second approach, remote sensing was used and N recommendation map was developed using the moderate-resolution imaging spectroradiometer (MODIS) leaf area index (LAI) and normalized difference vegetation index (NDVI) satellite data, and a minimum requirement of 60 kg N ha^?1 and maximum of 120 kg N ha^?1 was estimated through this approach.     

河北平原中低产区小麦与玉米生产现状及增产潜力分析

本文基于2000—2013年MODIS/NDVI遥感信息与主要粮食作物的统计数据,分析了河北平原中低产区冬小麦和玉米生产的时空格局,并利用各县粮食作物主要生育期累积NDVI的逐年值、14年的最大值及单产统计数据,采用最小二乘法原理,进行数值曲线拟合,构建了单产遥感估测模型,估算了河北平原中低产区冬小麦和玉米的增产潜力。结果表明:1)冬小麦在邯郸和衡水的最大生产力水平较高,在沧州、廊坊及邢台中部的最大生产力水平较低,即后者挖掘增产潜力之后也很难达到前者的最大生产力水平;玉米的最大生产力水平普遍较高,挖掘增产潜力后均可达到较高的生产力水平。2)冬小麦和玉米总产增产潜力在沧州和邯郸较大;冬小麦单产增产潜力多低于10%,平均增产356 kg?hm?2(5.87%);玉米单产增产潜力多高于10%,平均增产798 kg?hm?2(12.33%);单产增产潜力区域分布不同,冬小麦为廊坊保定沧州邯郸邢台衡水,玉米为邢台邯郸保定沧州衡水廊坊。3)以河北平原近14年来作物累积NDVI的最大值估算的全区冬小麦增产潜力为3.90亿kg,玉米增产潜力为9.62亿kg,二者合计可增产13.52亿kg,约相当于区域冬小麦和玉米理论可达增产潜力的1/5。本文估测粮食作物增产潜力的方法可以应用于估测多尺度范围、不同作物的增产潜力,研究结果可为相关部门的决策和管理提供依据。     

基于MODIS和NOAA数据尺度转换的若尔盖植被变化研究

为获得若尔盖地区较长时间序列的遥感植被指数,采用重采样技术和一元线性回归方法实现了GIMMS NDVI和MODIS NDVI的空间尺度转换和时间尺度外推。结果表明:（1）不同重采样方法对MODIS NDVI数据的影响与空间尺度有关,对GIMMS NDVI数据的影响则与空间尺度关系不大;（2）空间分辨率2.5 km,对不同植被类型可建立GIMMS NDVI和MODIS NDVI数据的一元线性转换关系,利用GIMMS NDVI拟合的结果与MODIS数据的差值统计符合正态分布;（3）1982—2013年,以1998年为节点若尔盖地区的植被先退化后逐渐恢复,尽管近几年植被指数平均水平高于研究初期,但局部地区的植被退化形势仍然比较严峻。     

滇东南喀斯特地区植被覆盖变化及其影响因素

利用MODIS NDVI数据资料集、标准气象站点的气候数据及社会经济统计数据,辅以叠置分析、空间统计分析和相关分析等方法,探讨了滇东南喀斯特地区植被覆盖的时空变化特征及其与气候因子、人类活动的关系。结果表明:滇东南喀斯特地区植被4月上旬进入生长季而9月中旬结束,2001—2010年植被覆盖呈现出上升的趋势,NDVI增加速率为0.03/10 a;滇东南喀斯特地区植被覆盖呈增加和减少趋势的面积分别占总面积的70.03%和29.97%,植被NDVI减少最为突出的区域主要集中在人口聚集的城镇周围及河流沿线,而增加的区域主要集中在高海拔山区;气候影响因素中的水分类因素即平均相对湿度、最小相对湿度和降水是滇东南喀斯特地区植被NDVI年内变化主要的影响因素,其影响有2个月左右的滞后期,温度类气候因子的滞后期为3个月左右,其他类型的气候因子滞后期约为2个月;滇东南喀斯特地区实施的退耕还林工程,极大地提升了植被覆盖度,而城镇化过程则使得城镇周边的极低、低植被覆盖度区面积增加。     

基于MODIS数据的山东省农作物旱情遥感监测报告

干旱胁迫能影响作物生长发育,给农业生产带来巨大危害.为了及时准确地掌握农作物旱情,本研究以山东省夏季农作物为研究对象,采用高等时间分辨率MODIS影像,建立了普适性较高的归一化差值植被指数,并通过观测分析其时间与空间维的变化情况判断农作物长势及旱情,从而建立了一种简便、高效的利用遥感技术监测旱情的方法.该方法适用于营养生长阶段的农作物,原理简单,操作方便,易于进行技术推广.     

我国西北地区东部时间序列NDVI数据集重建方法比较研究

高质量、长时序归一化植被指数(NDVI)数据集不仅是连续监测陆地表面特征的基础,也是研究气候与陆地生态系统变化的重要参数。本研究以生态环境较为脆弱的西北地区东部为例,借助多种时间序列重建方法对LTDR NDVI数据集中的噪声进行拟合重建,并结合农业气象资料和高质量NDVI数据,对不同重建方法的拟合结果开展适用性评价分析,结果表明,1)下垫面类型是影响重建方法拟合效果的重要因素。根据不同植被类型或作物生长特点,每种重建方法对其噪声消除能力有所不同;2)在年均NDVI较高(NDVI≥0.3),且NDVI曲线具有明显季节变化的草地、林地以及牧草等作物种植区域内,经过D-L拟合重建的NDVI具有较高的保真能力和适应性;3)在年均NDVI较低(NDVI<0.3),且植被季节生长变化不明显或NDVI曲线不呈季节对称性变化的稀疏植被区,以及以冬小麦为典型作物种植的区域内,经过S-G滤波重建的NDVI数据表现出相对较好的保真能力和适应性。     

Maternal salinity environment affects salt tolerance during germination in Anabasis setifera: A facultative desert halophyte

The effects of maternal salinity and light incubation on the salinity tolerance of the facultative halophyte Anabasis setifera during their germination stages were assessed. Seeds were collected from non-saline habitats in Egypt and saline habitats in the United Arab Emirates(UAE). The seeds of the two populations were germinated in 0, 100, 200, 400, 600 and 800 m M Na Cl, and incubated at 25°C/15°C in both 12-h light and 12-h darkness regimes and continuous darkness. Significantly more seeds germinated in the Egyptian population than in the UAE population. Salinity tolerance was significantly greater with the Egyptian population than with the UAE population, especially under the conditions of higher salinities. The difference in salinity tolerance between the seeds of two populations was attributed to their seed mass. In addition, germination was significantly faster for the Egyptian population than for the UAE population. Most of the saline treated seeds were able to recover their germination when transferred to distilled water, but this depended on their maternal salinity and light incubation. Recovery from higher salinities was significantly better for the seeds under darkness than for those under light in the UAE population, but the reverse was true for the seeds in the Egyptian population. The higher salinity tolerance for the A. setifera seeds from the non-saline Egyptian population and the lower salinity tolerance for the seeds from the saline UAE population cannot explain their natural distribution. Further studies about other possible roles, such as levels of different promoting and inhibiting phytohormones, are needed to understand the importance of salinity as an environmentally induced maternal effect.     

基于遥感和GIS技术的青海湖北岸植被覆盖动态变化监测

利用两个时相的TM和ETM数据,分别提取了青海湖流域的植被指数,根据植被指数转化模型,通过植被指数计算植被覆盖度。将植被覆盖度划分为4个不同的盖度等级,根据盖度级的空间分布特征,比较分析了试验区植被覆盖变化情况,分析引起植被覆盖变化的因素,为青海湖流域生态环境保护提供参考依据。     

Estimation of fire severity by use of Landsat TM images and its relevance to vegetation and topography in the 2000 Samcheok forest fire

The severity of the 2000 Samcheok forest fire was classified by using Landsat TM images, and the effects of vegetation structures and topographic conditions on fire severity were analyzed. The estimated normalized difference vegetation index differences between the pre and post-fire Landsat TM images were used as the criteria in determining the levels of fire severity–low, moderate, and extreme. According to the results from fire severity estimation, of the 10,600 ha forest stands, 28% was severely damaged by crown fires, 38% was moderately damaged, and the remaining 34% was damaged slightly by surface fires. The overall accuracy of the fire severity classification was 83% (Kappa coefficient = 0.76). The results of χ ²-tests showed that fire severity differed significantly with the vegetation and topographic conditions as follows. The coniferous stands, compared with the mixed and broad-leaved, were more vulnerable to fire damage; the higher the slope of fire sites, the greater the fire damage; the south was the most vulnerable aspect; fire severity of coniferous forest stands increased with increasing elevation. However, in the study area it was found that fire severity of broad-leaved forest stands were negatively related to the elevation of the corresponding fire sites and affected more by vegetation conditions rather than by topographic conditions.