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1.
以洞庭湖流域为研究区域,对MODIS13Q1植被产品数据的所有像元进行EVI时间序列重构后,采用滑动平均法、动态阈值法、最大变化斜率法以及Logistic函数拟合法等4种方法进行物候参数提取。对比分析后,选择了效果最佳的滑动平均法对2005年及2015年洞庭湖流域的EVI时间序列的遥感影像进行植被物候参数提取,分析近10年来研究区域植被物候特征变化。结果表明:滑动平均法提取的植被物候参数较准确,适用性较强;利用遥感手段能及时准确地监测大区域尺度植被物候变化,为研究区域气候变化等提供参考。 相似文献
2.
《中南林业科技大学学报(自然科学版)》2017,(9)
以4种MODIS时序数据为基础,以湖北省为研究区,开展区域森林类型快速提取的分类方法研究。将湖北省的森林植被划分为针叶林、阔叶林、混交林、竹林、灌木林和非林地6种地类,通过分析不同森林类型一年内的生长差异,根据各植被指数的均值建立了研究区各森林类型的分类参数,选取2010年MODIS数据产品NDVI第10期、NDVI第12期、NDVI第15期、EVI第10期、LAI第16期、LAI第17期数据,建立了针叶林、阔叶林、混交林、竹林、灌木林、非林地的决策树分类模型,并对研究区进行了分类。结果表明:植被指数均值曲线具有一定的区域地类代表性,分类参数对不同森林类型具有较强的分异性;将分类结果与第八次全国森林资源清查结果相比较,森林类型分类总体精度为85.45%,KAPPA系数为0.770 1,效果较好,说明通过MODIS数据进行区域的森林类型提取是可行的。 相似文献
3.
针对MODIS 16 d合成的N_(dvi)时间序列数据的重构问题,以厦门岛为实验区,以林地为实验类型,基于双Logistic函数拟合法、非对称高斯函数拟合法和Savitzky-Golay滤波法,进行区域时间序列N_(dvi)数据的重构措施及验证研究。结果表明,3种重建方法均可以整体提高时序N_(dvi)平均值,有效地避免异常值及噪声的干扰,A-G函数与D-L函数拟合法重建的时序N_(dvi)更能反映林地成长的曲线特征;S-G滤波法和A-G函数拟合法在保持高质量N_(dvi)真实值特征方面比D-L法效果较好;在生长季峰期内,S-G滤波法拟合效果要优于A-G函数和D-L函数拟合算法,更能反映林地成长的最佳情况。 相似文献
4.
湖南省森林资源丰富,但森林质量不高,抗逆能力较差,林地干旱及其次生灾害已成为湖南林业发展的重大威胁。文中通过多源遥感数据融合模型(STARFM模型与SADFAT模型)将高时间分辨率的MODIS数据和高空间分辨率的LANDSAT数据进行融合,从融合后的影像中提取地表温度(LST)与植被指数(NDVI)2个林地干旱因子,构建温度-植被干旱指数模型(TVDI),利用模型对湖南省2016年6—8月森林生长季每月3天的林地干旱进行了反演,绘制了林地干旱专题图,并对湖南省夏季干旱分布情况进行了分析,为准确、快速地对湖南省林地干旱进行监测和预警提供了一种科学方法。 相似文献
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6.
NDVI是识别植被的一个重要参数,与植被盖度有明显的相关性。NDVI时序变化曲线反映了植被随时间的推移而发生的生长和变化状况。本研究利用2000~2009年长沙市MODIS数据,采用均值变化法分析了长沙市连续10 a NDVI的时空演变。结果显示:这10 a间,植被在生长季(4~10月)总体长势较好,年均NDVI都在0.9以上;从时间角度来看,NDVI呈现缓慢增加趋势,但期间出现2个峰值和1个最低值,分别为2002年、2006年和2003年;从空间角度来看,东部NDVI最高,西部其次,中部最低,植被覆盖以中、高植被覆盖区为主,随时间变化,NDVI在空间上表现出波动变化;NDVI年代际变化率表明,长沙市NDVI值在2000~2009年连续10 a时间里,既有增加,也有减少。2003、2007和2009年年代际变化率为负值,其余年份为正值。 相似文献
7.
高空间、时间分辨率遥感数据在林业遥感变化监测方面具有重要的作用,然而,对于特定传感器获取的遥感影像在空间和时间分辨率上存在着不可调和的矛盾。本文针对神农架林区多云雾高时空分辨率数据缺乏的现状,提出了一套区域尺度高时空分辨率植被覆盖度数据构建方法。首先,利用LandSat8数据进行预处理,得到高分辨率的NDVI数据,并将MODIS NDVI数据进行重投影、重采样等预处理;其次,利用STARFM模型进行高分辨NDVI预测,利用评价因子选择最佳算法参数,并利用二分模型计算植被覆盖度;再次,以LandSat8获取的真实数据与预测数据进行精度评价;最后,选取黑龙江小兴安岭西北部林区生长季数据进行验证试验。结果表明:利用该方法可以在神农架林区获得预测日期的较好的NDVI及植被覆盖度,精度分别为90.8%、82.60%。此外,通过验证试验,可以获得同年生长季小兴安岭林场较好的NDVI以及植被覆盖度,精度分别达到92.86%、88.65%。 相似文献
8.
湖南省森林资源丰富,森林覆盖率达47.77%,但森林资源质量不高,抗逆能力较差;旱灾和因旱灾引发的次生灾害可能会成为湖南林业发展的最大威胁。以MODIS数据为数据源,提取林地干旱遥感监测因子的植被指数(NDVI)与地表温度(LST),利用温度植被干旱指数(TVDI)模型,并进行湖南省2013—2015年森林植被生长季的林地干旱反演,分析得到2013年湖南全境林地旱情从3月到8月发生不同程度的加重的现象,生长季前期干旱区域分布在湘南,湘西北地区出现干旱的程度较低;生长季后期洞庭湖区及湘中地区干旱程度较为严重。进一步反演2014年和2015年每年3—5月林地干旱时空分异特点,在时间尺度上,2015年3—5月旱情有逐月加重趋势,与2014年相比,其同比月份的干旱程度较高。在空间分布上,旱情较为严重的区域多分布在湘南和湘中的局部区域。将2013年8月湖南省气象局发布的干旱等级监测数据,与依照干旱反演得出的TVDI值所确定的干旱等级进行比较,干旱等级的一致率达81.4%,由此,随着湖南省卫星减灾应用工程不断完善,可以成为林地干旱监测预警的有效实现途径之一。 相似文献
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10.
《中南林业科技大学学报(自然科学版)》2015,(11)
森林类型的识别对于掌握森林生态系统和自然环境变化具有重要意义。针对单一时相遥感数据提取森林植被类型信息方法的局限性,以中国东北三省为研究区,探讨了基于多时相MODIS遥感数据,实现主要森林类型识别的方法。将东三省的森林植被划分为非林地、针叶林、阔叶林、针阔混交林、灌木林5种类型,通过分析不同森林类型一年内生长差异,选取多时相NDVI第10期、NDIV第23期、EVI第10期、LAI第20期特征数据,建立了非林地、针叶林、阔叶林、针阔混交林、灌木林的决策树模型,实现了森林类型信息的识别,得出了东三省的森林覆盖率42.39%,植被类型分类总体精度为86.7%,与第八次全国森林资源清查的东三省结果对比,森林覆盖率提取精度高达95.6%。说明应用多时相的MODIS遥感影像可以实现大尺度森林资源信息的快速提取,在大范围的植被类型调查与监测方法具有较大的应用价值。 相似文献
11.
Sun Xiaoying 《中国林业科技(英文版)》2012,(3):62-62
To improve the accuracy and effectiveness of forest pests forecasting,based on current forecast model,integrating the database and WebGIS technology,a practical design and construction approach of forest pest knowledge base was put forward,and the forecast system on Web application framework was realized with satisfactory empirical results. 相似文献
12.
《林业研究》2017,(4)
Active organic carbon in soil has high biological activity and plays an important role in forest soil ecosystem structure and function. Fire is an important disturbance factor in many forest ecosystems and occurs frequently over forested soils. However, little is known about its impact on soil active organic carbon(SAOC), which is important to the global carbon cycle. To investigate this issue, we studied the active organic carbon in soils in the Larix gmelinii forests of the Da Xing'an Mountains(Greater Xing'an Mountains) in Northeastern China, which had been burned by high-intensity wildfire in two different years(2002 and 2008). Soil samples were collected monthly during the 2011 growing season from over 12 sample plots in burned and unburned soils and then analyzed to examine the dynamics of SAOC. Our results showed that active organic carbon content changed greatly after fire disturbance in relation to the amount of time elapsed since the fire. There were significant differences in microbial biomass carbon, dissolved organic carbon, light fraction organic carbon, particulate organic carbon between burned and unburned sample plots in 2002 and 2008(p0.05). The correlations between active organic carbon and environmental factors such as water content, p H value and temperature of soils, and correlations between each carbon component changed after fire disturbance, also in relation to time since the fire. The seasonal dynamics of SAOC in all of the sample plots changed after fire disturbance; peak values appeared during the growing season. In plots burned in 2002 and 2008, the magnitude and occurrence time of peak values differed. Our findings provide basic data regarding the impact of fire disturbance on boreal forest soil-carbon cycling, carbon-balance mechanisms, and carbon contributions of forest ecosystem after wildfire disturbance. 相似文献
13.
Active organic carbon in soil has high biological activity and plays an important role in forest soil ecosystem structure and function. Fire is an important disturbance factor in many forest ecosystems and occurs frequently over forested soils. However, little is known about its impact on soil active organic carbon (SAOC), which is important to the global carbon cycle. To investigate this issue, we studied the active organic carbon in soils in the Larix gmelinii forests of the Da Xing’an Mountains (Greater Xing’an Mountains) in Northeastern China, which had been burned by high-intensity wildfire in two different years (2002 and 2008). Soil samples were collected monthly during the 2011 growing season from over 12 sample plots in burned and unburned soils and then analyzed to examine the dynamics of SAOC. Our results showed that active organic carbon content changed greatly after fire disturbance in relation to the amount of time elapsed since the fire. There were significant differences in microbial biomass carbon, dissolved organic carbon, light fraction organic carbon, particulate organic carbon between burned and unburned sample plots in 2002 and 2008 (p < 0.05). The correlations between active organic carbon and environmental factors such as water content, pH value and temperature of soils, and correlations between each carbon component changed after fire disturbance, also in relation to time since the fire. The seasonal dynamics of SAOC in all of the sample plots changed after fire disturbance; peak values appeared during the growing season. In plots burned in 2002 and 2008, the magnitude and occurrence time of peak values differed. Our findings provide basic data regarding the impact of fire disturbance on boreal forest soil-carbon cycling, carbon-balance mechanisms, and carbon contributions of forest ecosystem after wildfire disturbance. 相似文献
14.
Jan Verbesselt Andrew Robinson Christine Stone Darius Culvenor 《Forest Ecology and Management》2009,258(7):1166-1173
Insect-induced tree mortality can cause substantial timber and carbon losses in many regions of the world. There is a critical need to forecast tree mortality to guide forest management decisions. Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery provides inexpensive and frequent coverage over large areas, facilitating forest health monitoring. This study examined time series of MODIS satellite images to forecast tree mortality for a Pinus radiata plantation in southern New South Wales, Australia. Dead tree density derived from ADS40 aerial imagery was used to evaluate the performance of change metrics derived from time series of MODIS-based vegetation indices. Continuous subset selection by LASSO regression and model assessment using a variant of the bootstrap were used to select the best performing change metrics out of a large amount of predictor variables to account for over-fitting. The results suggest that 250 m 16-daily MODIS images are effective for forecasting tree mortality. Seasonal change metrics derived from the Normalized Difference Vegetation Index (NDVI) outperformed the Enhanced Vegetation Index (EVI) and the Normalized Difference Infrared Index (NDII). Temporal analysis illustrated that optimal forecasting power was obtained using change metrics based on three years of satellite data for this population. The forecast could be used to optimise the scheduling of detailed forest health surveys and silvicultural operations which currently are planned based on stratified, annual assessments. This coarse-scale, spatio-temporal analysis represents a potentially cost-effective early warning approach to forecasting tree mortality in pine plantations by identifying compartments that require more detailed investigation. 相似文献
15.
研究了不同立地条件、不同经营措施对高氏甜龙竹生长的影响。结果表明：在云南、四川、重庆等10个不同环境条件的试验点,高氏甜龙竹的生长状况差异显著,其中在云南省元江县、重庆市武隆区和云南普洱市思茅区生长较好,3年生竹笋年产量分别达到30.03、27.23和26.20 t/hm2,而在云南嵩明县的生长相对较差,笋年产量仅为10.93 t/hm2;经营措施也影响着高氏甜龙竹的生长,采用全面整地,旱季时每月对竹丛进行1次浇水,浇水量为900 kg/丛,造林时施用大量有机肥,出笋高峰期施适量的氮、磷、钾复合肥（500 g/丛）,可促进竹林生长,提高笋产量和笋品质。 相似文献
16.
刺槐蒸腾耗水的动态研究(英文) 总被引：2，自引：0，他引：2
推算林分的年总耗水量 ,首先要确定林分的年总蒸腾量 .该文以LI 16 0 0稳态气孔仪在 1998～2 0 0 0年生长季各月典型天气的实测数据和常规气象数据为基础 ,应用Penman Monteith方程模拟了刺槐林的日蒸腾过程 ,并以此计算了生长季的连续日蒸腾 .刺槐林林冠层截留净辐射由实测数据 (Rn)与叶面积指数 (LAI)建立的消光系数 (k)数学关系确定 ,冠层整体气孔阻力由实测数据拟合经验式计算 .经与实测结果对比 ,模拟的相对误差平均在 12 %以内 .由全年连续日蒸腾模拟计算 ,1998年至2 0 0 0年 5月～ 10月生长季不同密度刺槐林的平均总蒸腾量分别为 192 4 6 ,187 0 7和 195 5 9mm . 相似文献
17.
不同强度人为干扰15a后,经解析木分析表明,轻度干扰林分中马尾松的胸径、树高、材积均保持良好的生长趋势,总生长量比中度干扰和重度干扰林分高,连年生长量和平均生长量在幼龄期也高于后二者,重度干扰林分的各要素生长量均增长缓慢。这些结果表明超过一定限度的人为干扰阻碍了林木的生长发育。 相似文献
18.
【目的】研究基于遥感影像的森林扰动信息定量提取及其对树高估算的影响,为遥感反演森林参数(树高、生物量)提供参考和借鉴。【方法】选取黑龙江省凉水国家级自然保护区为研究区,以1984—2006年33期Landsat TM/ETM+多光谱遥感影像为数据源,对其进行缨帽变换提取缨帽角(TCA)和缨帽距离(TCD)2个扰动监测指数,采用时间轨迹分析方法(LandTrendr)对TCA与TCD指数进行时间序列重构,分别提取扰动发生的前一年(DBYEA)、扰动发生前的光谱值(DBVAL)、扰动持续时间(DDUR)、扰动量级(DMAG)、扰动后开始修复的时间(RBYEAR)、扰动后开始修复的光谱值(RBVAL)、修复量级(RMAG)和修复持续时间(RDUR)8个时间序列扰动参数。基于单时相Landsat影像光谱信息与单时相Landsat影像光谱信息+森林扰动参数2组变量分别采用随机森林(RF)算法估算树高。【结果】采用单时相Landsat影像光谱信息结合基于TCA和TCD提取的16个时间序列扰动参数建立的树高反演模型预估精度比采用单时相Landsat影像光谱信息建立的树高反演模型预估精度提高6.34%,均方根误差(RMSE)降低0.50 m。树高反演模型中基于TCA提取的时间序列扰动参数变量重要性高于基于TCD提取的时间序列扰动参数变量重要性。【结论】基于LandTrendr提取的森林时间序列扰动参数能够增强反射率与树高之间的相关性,提高遥感树高模型的反演精度,基于TCA提取的森林时间序列扰动参数对树高的解释能力高于基于TCD提取的森林时间序列扰动参数。 相似文献
19.
The scarcity of large old-growth forests has made it challenging to quantify disturbance regimes in Central Europe. The objective of this study was to reconstruct the history of disturbance in an old-growth Fagus-Abies forest reserve in Slovenia using a dendroecological approach. We extracted cores from canopy trees blown down during a recent windthrow event and identified growth releases in the tree-ring series using boundary-line release criteria to infer past disturbances. A total of 216 release events were identified from 88 trees. Between 1790 and 1990, moderate, asynchronous release events were present in nearly every decade of the disturbance chronology, suggesting a history of frequent, low severity disturbance. However, there were also peaks in the chronology corresponding to synchronous release events in a large proportion of the trees, suggesting that less frequent, intermediate severity disturbance events played an important role in forest development. These events are likely caused from wind damage associated with local thunderstorms, which seem to occur at intervals between 20–80 years on the study site. Thus, in addition to the small-scale gap phase processes operating in the forest, the results indicate that periodic intermediate severity disturbance events are an important component of the disturbance regime in mountain forests of Central Europe. 相似文献
20.
Tree foliage is a nutrient-rich and important source of green fodder to sustain the livestock during the lean winter period
of a season in the low and mid hill regions of Indian Himalaya. Knowledge of the variations in mineral nutrient composition
of the foliage during an active growth season helps in determining optimum lopping time to harvest nutrient-rich fodder. Changes
in the nutrient concentrations of Albizia stipulata and Ougenia oojeinensis foliage during the annual growth season were studied
to find out an optimum lopping time. Two dissimilar trends in variation of nutrients in foliage with the advancement of growth
season were observed. These were: (1) depletion/dilution of N, P, K and S and (2) accumulation of Ca, Mg and Na. The depletion
was more from October onwards, and accumulation reached to its maximum in November-December. Therefore, the period from October
to December, preferably November, can be regarded as optimum lopping time for A. stipulata. For O. oojeinensis, the corresponding
time could be September to November, preferably October. Ougenia foliage contained higher concentration of N, P, Ca, Mg, and
Na than that of Albizia.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献