黄土区露天煤矿排土场植被恢复的水肥响应

矿区复垦植被与排土场土壤环境之间存在着复杂的交互关系,两者相互依存且制约;特别是土壤肥力和水分与植被恢复关系密切。因此,如何实现复垦植被与土壤水肥协调发展以促进生态系统的改善是矿区生态恢复的核心问题。为此,本文选择山西平朔矿区安太堡露天煤矿排土场,通过典型样地调查方法来分析露天煤矿排土场土壤水肥特性与复垦植被因子之间的关系,同时构建耦合协调度模型来定量分析土壤水肥因素对植被生长的影响,并判断土壤水肥与复垦植被的协调程度。结果表明:在0~40 cm的土层中,土壤含水量随着深度的增加而增大,土壤有机质和全氮的变化趋势与之相反;土壤肥力特性相对于土壤含水量对复垦植被生长的影响更大;土壤水肥环境与复垦植被之间的耦合协调关系皆为基本协调。在土壤养分贫瘠且生态环境恶劣的黄土高原矿区,改善土壤肥力状况、筛选适宜的植被复垦模式及控制植被密度是生态重建的关键。本研究可为黄土区露天煤矿排土场土地复垦与生态恢复提供理论依据和参考。     

基于多时相Landsat遥感影像的海州露天煤矿排土场植被时空特征分析

矿区土地复垦是目前土地整理的一项重要内容,也是矿区可持续发展实现的保障.矿区植被及其恢复状况是矿区土地复垦质量的一种重要的指示器,表征土地复垦的程度与质量.研究基于1975～2000年共4期遥感影像,构建植被覆盖度指数,考察辽宁省阜新市海州露天煤矿排土场25a来植被生长状况及时空变化特征.分析结果表明:1975～2000年间,研究区植被处于不断生长、逐渐恢复的状态,并存在明显的空间差异.时间尺度上,植被覆盖度较高(0.4～0.6)的区域所占面积比例从1975年的14.04%增长到2000年的34.83%;空间分布上,植被覆盖度低(0～0.25)的区域多分布在台地之间相连接的边坡位置上,植被覆盖度较高(0.25～0.6)的区域则分布于台地内部的平坦地面上.     

山西平朔露天矿区不同年限复垦地植被重建特征对比分析

平朔矿区是中国首个露井联采的亿t级矿区,剧烈的采煤活动导致矿区局部植被彻底损毁,植被重建是矿区生态系统恢复重建的保障,目前针对长期复垦序列下矿区复垦地植被重建特征与演替规律的研究较少。以复垦年限分别为6 a、7 a、25 a和27 a的复垦排土场和原地貌样地为研究对象,采用时空替代法和描述性统计分析法分析了不同复垦年限下复垦地的植被重建特征,并与原地貌进行了对比分析。研究结果表明：(1)植被重建工作显著提高了复垦地的物种丰富度,各复垦地乔灌植株的物种丰富度明显高于原地貌。但在重建植被演替过程中,并非随复垦年限增加,物种丰富度越来越高;复垦地Shannon-Wiener指数随复垦年限增加呈先增后减的变化趋势,该值在R-25a样地达到峰值(0.62),其与复垦地的植物物种组成及其自身生长习性、土壤条件、降水等自然条件和人为干扰等息息相关。(2)从乔木植株的生长状况来看,刺槐作为先锋树种,是植被重建时可优先选择的乔木树种。从复垦地草本植株组成来看,草本植物以多年生为主,占比77.78%;从草本植株的重要值来看,草本优势种以禾本科(Gramineae)、菊科(Compositae)和豆科(Le...     

平朔黄土露天矿区复垦地表层土壤微生物与酶活性分析

矿区是当今世界陆地生态系统被破坏和退化最严重的区域之一,在进行露天煤矿土地复垦与生态重建时不仅要恢复地表植被和生物,还应重视地下土壤微生物生态系统的构建,而国内外相关研究多集中在植被重建及土壤理化性质监测方面,利用土壤微生物及酶活性揭示矿区重构土壤状况的研究尚不多见。通过8个样地24个土壤剖面的采样分析,采用时空替代法和单因素方差分析法对平朔矿区不同复垦年限的排土场和原地貌0—20 cm表层土壤中细菌、真菌、放线菌的数量及蔗糖酶、脲酶和磷酸酶活性及变化进行研究,旨在分析其特征及差异。研究结果表明:(1)从微生物数量及酶活性特征来看,无论复垦年限的时间长短,细菌数量在3类微生物中占有绝对优势,占微生物总数的99.20%以上,其次是放线菌,真菌的数量最少;脲酶活性在3种酶中活性最大,其次是蔗糖酶活性,磷酸酶活性最低。(2)从微生物数量和酶活性的变化状况来看,3类微生物数量和3种酶活性在0—20 cm土层随复垦年限的变化趋势相一致,均随复垦年限的变化先增长后降低,而后又随着复垦年限的增长不断增加。(3)在0—20 cm土层,复垦27年的南排土场的土壤细菌、放线菌和真菌数量在复垦后达到了189.3333×10⁵ cfu/g、0.1312×10⁵ cfu/g和1.1463×10⁵ cfu/g,复垦效果达到原地貌3类土壤微生物数量的65.88%、66.46%和67.74%;蔗糖酶、脲酶和磷酸酶活性分别达到1.9600 mg 100 g^-1 h^-1、6.3600 mg 100 g^-1 h^-1和1.4533 mg 100 g^-1 h^-1,复垦效果分别达到原地貌83.40%、86.30%和86.85%。因此开展矿区土地复垦后土壤微生物及酶活性的相关研究,能够在一定程度上及时反映土地复垦后的土壤质量以及生态系统的恢复状况,以便采取更加合理的复垦方法来提高矿区生态恢复的速度和效果。     

基于高光谱遥感的排土场植被覆盖与植物多样性分析

排土场作为矿区的典型扰动斑块,属于矿区生态修复的重点对象.研究人为重建的排土场生态系统物种多样性情况,分析不同坡度下植被覆盖度和植物配置,可为排土场的植被重建工程提供植物物种筛选依据和配置方案.本文以宝日希勒煤矿外排土场北坡为研究区,运用无人机高光谱遥感技术获取研究区影像,结合野外实测手段建立矿区典型植物光谱库,采用光...     

植被重建对露天煤矿排土场土壤酶活性的影响

植被重建是露天煤矿排土场生态恢复的关键措施,深入了解植被建设对土壤酶活性的影响,对于合理选择适宜于矿区生态恢复的人工植被和加速矿区土壤生态恢复具有重要意义。通过野外调查采样和室内分析,研究了黑岱沟露天煤矿排土场植被重建和恢复对浅层(0—20 cm)土壤酶活性(包括3种氧化还原酶:过氧化氢酶、多酚氧化酶、脱氢酶,4种水解酶:蔗糖酶、脲酶、磷酸酶、纤维素酶)的影响。结果表明:相比未进行植被建设的新排土场裸地,植被重建显著改善了土壤酶活性和理化性质,建植18a后土壤酶活性可恢复到天然植被区的65%—76%,水解酶恢复速率(平均为86.9%)快于氧化还原酶(平均为42.7%),其中土壤磷酸酶恢复速率最快(平均为天然植被区的154.7%),其次为蔗糖酶(74.3%)、纤维素酶(59.9%)、脲酶(58.5%)、过氧化氢酶(52.1%)和脱氢酶(38.1%),多酚氧化酶恢复最慢(为37.8%)。植被恢复进程中,建植10a期土壤酶活性年均恢复速率最快(平均为6.0%/a),15a变缓(4.8%/a),18a迅速降低(3.2%/a)。同时植被配置类型对土壤酶活性影响显著,土壤酶活性与土壤主要理化因子具有较高的相关性。上述结果反映了植被重建能显著改善矿区排土场的土壤酶活性,植被恢复进程中水解酶恢复速率快于氧化还原酶,恢复初期快于后期,但土壤酶活性的恢复需要一个漫长的过程。     

露天煤矿排土场植被重建对土壤呼吸的影响

植被重建是露天煤矿生态恢复的重要途径, 植被恢复的最终目的是土壤生境的恢复, 而土壤呼吸是反映土壤健康状况的关键指标之一。采用LI-8100 土壤碳通量观测系统, 对内蒙古黑岱沟露天煤矿排土场不同植被配置下的土壤呼吸进行了测定, 分析了植被配置、生物、环境因子对土壤呼吸速率的影响。结果表明: 植被配置类型对土壤呼吸影响显著, 乔-草型和乔-灌-草型配置下的土壤呼吸速率接近(平均2.68 μmol CO2·m^–2·s^–1, P>0.05), 显著高于乔-灌型(2.33 μmolCO2·m^–2·s^–1, P<0.001), 但都显著低于邻近撂荒地土壤呼吸(3.64 μmol CO2·m^–2·s^–1, P<0.001)。4 种植被类型下的土壤呼吸日变化都呈单峰曲线, 但峰值出现的时间不同。土壤呼吸与植被盖度、草本多度、丰富度、生物土壤结皮盖度、厚度、土壤全氮、硝态氮、有机质含量显著正相关, 与灌木盖度、土壤体积含水量、容重和铵态氮含量显著负相关。植被重建显著影响矿区排土场土壤呼吸, 植被配置类型、草本盖度多度和土壤碳氮水平是影响土壤呼吸时空变异的关键因子。     

黄土区露天煤矿排土场土壤与地形因子对植被恢复的影响

在脆弱的生态环境改善和恢复过程中,植被恢复与重建扮演着重要的角色。黄土露天煤矿区生态环境极其脆弱,认识矿区损毁土地植被恢复与地形、土壤因子之间的作用规律对矿区土地复垦与生态恢复改善至关重要。为此,选择山西平朔安太堡露天煤矿南排土场对2条样带27个复垦样地的土壤、地形、植被参数进行了采集与测定,并应用单因素方差分析与CANOCO4.5软件的降趋势对应分析和冗余分析研究了地形与土壤因子对植被恢复的影响。结果表明:植被与土壤变量之间呈显著相关,与地形变量之间相关性不明显;坡度主要影响草本覆盖度,坡向与有机质和速效磷之间具有线性相关性;速效钾对植被的变化起着重要的作用;土壤容重与砾石含量对土壤养分含量具有明显的指示作用;有机质与全氮呈显著正相关,各土壤养分指标之间存在明显的相关关系。为了改善和恢复黄土区露天煤矿排土场脆弱的生态系统,应该考虑植被和土壤的联合演替。在当地的生态环境状况下土地复垦与生态恢复的关键是改善土壤状况和增加人工植被,同时加强对排土场人工和自然植被的保护。     

基于图像融合与混合像元分解的城市植被盖度提取

城市植被盖度提取对于开展城市绿色空间保护和城市规划具有重要意义。随着遥感技术的发展,混合像元分解模型被广泛用于从中等分辨率的多光谱影像提取城市植被盖度,但较低的影像空间分辨率限制了该模型的应用领域。为此,以杭州市为例,首先引入Gram-Schmidt(GS)方法对Landsat ETM+的多光谱波段和全色波段进行融合,再通过混合像元分解模型从ETM+融合影像上提取城市植被盖度,最后利用SPOT影像进行精度检验。结果发现,采用GS方法对影像进行融合后,标准差、信息熵、平均梯度提高,相对偏差小于0.07,说明在保留多光谱信息的基础上提高了其空间分辨率。与SPOT影像相比,在融合影像上75%以上样本的植被盖度值相似,误差较大的区域是市区植被特别稀疏或茂盛的像元。与源影像相比,从融合影像上提取的植被盖度的均方根误差和系统误差降低了0.01。该方法在降低城市植被监测成本、提高监测精度方面具有潜力。     

安太堡露天煤矿排土场土壤种子库

采用种子萌发法研究了安太堡露天矿排土场的土壤种子库,共统计到17种植物种子,分属5科,以1年生草本植物种子为主.排土场土壤种子库具有极大的时空异质性,地上植被与土壤种子库群落组成上的相似性程度较低,复垦后期土壤种子库间相似性系数较低.随着复垦时间、复垦模式或立地条件的不同,土壤种子库的种类、密度各不相同.选择正确的复垦模式,有利于土壤种子库自我更新能力的增加和排土场生态系统稳定,对排土场的土地复垦和生态重建具有重要意义.     

高原河谷城镇化对植被覆盖度的影响

以典型的高原河谷城市——西宁市为例，定量分析了2000-2015年研究区景观格局及植被覆盖度的时空演变，揭示了高原河谷地区的城镇建设对植被覆盖度的干扰过程及生态环境质量的影响。结果表明：（1）2000-2015年间，西宁市城镇面积增幅为25.99%，总体城镇化率为4.76%，各区县城镇化水平差异较大；（2）西宁市平均植被覆盖度呈增加趋势但不显著（P < 0.57）。植被覆盖度以中高和高植被覆盖度为主，空间上呈现"东西低-南北高"的分布特征，退耕（牧）还林（草）区的植被覆盖度显著增加（P < 0.01），说明生态恢复工程效果显著；（3）区县尺度上，城镇化速率与中高覆盖植被面积变化呈显著负相关（P < 0.01），区县内生态质量有所下降，城镇发展程度和区位条件的差异是影响中高覆盖度植被变化的主要因素；（4）格网尺度上，建成区及其周边区域的低覆盖植被面积呈显著增加趋势（P < 0.01），表明城镇内部区域生态质量有所改善。研究结果对保护和提高西宁市生态环境质量及合理推进城镇建设等方面具有重要意义。     

Spectral feature differences between shrub and grass communities and shrub coverage retrieval in shrub-encroached grassland in Xianghuang Banner,Nei Mongol,China北大核心CSCD

Aims: Shrub-encroached grassland has become an important vegetation type in China's arid and semi-arid region. Our study objective is to explore the spectral features of shrub and grass communities, as well as their empirical relationships with shrub coverage. The quantitative estimation of shrub cover based on medium-resolution Landsat satellite imagery provides the practical basis for long term retrieval of large areas of shrub expansion in the grassland region. Methods: Linear models and Multiple Endmember Spectral Analysis Model (MESMA) based on medium resolution Landsat satellite imagery were developed to quantify the shrub coverage in a shrub-encroached grassland region in Xianghuang Banner, Nei Mongol using the spectral features and their seasonal differences between the shrub and grass communities. Important findings: Compared to Leymus chinensis and Stipa krylovii dominated grass communities, Caragana microphylla community had a higher normalized difference vegetation index (NDVI), modified red edge normalized difference vegetation index (mNDVI705), and red edge slope. The red edge position of C. microphylla community shifted to longer wavelengths. The average and the maximum shrub coverage was 13% and 25%, respectively, in the shrub-encroached grassland based on both models. The correlation coefficient of determination (R2) and root mean square error (RMSE) of the linear model was 0.31 and 0.05, respectively. We found that the linear model based on seasonal differences of shrub and grass community was more suitable for retrieving shrub coverage in the study area from medium resolution imagery than the MESMA model that is based on mid-summer images.     

Vegetation changes in restored semi-natural meadows in the Turku Archipelago of SW Finland

In the Turku Archipelago of SW Finland the traditional animal husbandry dramatically decreased in 1950s after which the unused semi-natural pastures and meadows began to develop into less species rich shrub and tree communities. Restoration of some semi-natural meadows and pastures started in the late 1970s. Removing trees and shrubs, grazing, mowing, and pollarding deciduous trees were used as restoration of practises. Vegetation changes were followed from forty-one permanent sample plots established on restored areas. In this paper the data before restoration and 7–8 years after the first monitoring was analysed with parametric tests. The sample plots were divided into three restoration groups where the main restoration practises were: group 1. grazing, group 2. thinning (clearing plots from shrubs and removing some trees), group 3. thinning, mowing, and grazing (old wooded meadows). The results showed that: (1) The vegetation changed during analysed time. The number of species increased in all restored areas even though the changes were more pronounced in grazed areas and wooded meadows than in thinned areas. During restoration many common herb and grass species immigrated into the sample plots, but very few new indicator species of meadows were recorded. Most of the new species were found in few numbers in a sample plot which led to the significant increase in the number of sparse species (percentage cover < 1) in all restoration groups. The grasses benefited more from the restoration than herbs increasing their percentage cover significantly in grazed areas and in wooded meadows. In thinned areas the total percentage cover of the ten most dominant herb and grass species increased significantly. (2) The different restoration groups changed vegetation quite similarly. In grazed areas and in wooded meadows significant changes were slightly more numerous than in thinned areas. (3) The differences between the islands in vegetation changes were not pronounced. The added variance components among islands increased during restoration which probably indicated that the restoration practises as well as the species pool of the islands influenced the success of restoration.     

Spectral feature differences between shrub and grass communities and shrub coverage retri- eval in shrub-encroached grassland in Xianghuang Banner,Nei Mongol,China

Aims Shrub-encroached grassland has become an important vegetation type in China’s arid and semi-arid region. Our study objective is to explore the spectral features of shrub and grass communities, as well as their empirical relationships with shrub coverage. The quantitative estimation of shrub cover based on medium-resolution Landsat satellite imagery provides the practical basis for long term retrieval of large areas of shrub expansion in the grassland region. Methods Linear models and Multiple Endmember Spectral Analysis Model (MESMA) based on medium resolution Landsat satellite imagery were developed to quantify the shrub coverage in a shrub-encroached grassland region in Xianghuang Banner, Nei Mongol using the spectral features and their seasonal differences between the shrub and grass communities. Important findings Compared to Leymus chinensis and Stipa krylovii dominated grass communities, Caragana microphylla community had a higher normalized difference vegetation index (NDVI), modified red edge normalized difference vegetation index (mNDVI₇₀₅), and red edge slope. The red edge position of C. microphylla community shifted to longer wavelengths. The average and the maximum shrub coverage was 13% and 25%, respectively, in the shrub-encroached grassland based on both models. The correlation coefficient of determination (R²) and root mean square error (RMSE) of the linear model was 0.31 and 0.05, respectively. We found that the linear model based on seasonal differences of shrub and grass community was more suitable for retrieving shrub coverage in the study area from medium resolution imagery than the MESMA model that is based on mid-summer images.     

Restoration of a Restinga Sandy Coastal Plain in Brazil: Survival and Growth of Planted Woody Species

In this article we report the results of an experiment introducing 17 native shrub and tree species into a Brazilian restinga (i.e., coastal sandy plain vegetation). Restingas have been affected by human impact for about 8,000 years, and human occupation for housing, tourism, and land speculation has recently increased in such a way that there is a need for conservation of remnant patches and restoration of degraded areas throughout the coast to protect biodiversity. Our study site is a remnant located in Rio de Janeiro, the second largest city in the country, and has been subjected in the past to deforestation, man‐made fire, and sand extraction. Although trees and shrubs predominantly compose natural restinga vegetation, local vegetation after impact was replaced by an exotic grass cover, which meant a drastic reduction in species richness. Thus, in this experiment we removed the grass cover, introduced shrub and tree species, and monitored survival and growth of 20 plants per species for 2 years. Despite the adversities imposed by the nutrient‐poor sandy soil, 70% of the species showed high survival percentage and considerable growth. This report on restoration initiatives in the restingas points out the viability of shrub and tree plantation following exotic grass removal as a strategy to restore Brazilian coastal vegetation.     

Seed dispersal in the dung of large herbivores: implications for restoration of Renosterveld shrubland old fields

Species-rich, winter-rainfall, microphyllous Renosterveld vegetation in the Western Cape Province of South Africa has largely been transformed for production of wheat and wine. Remaining fragments thus have high conservation value. Abandoned old fields adjacent to natural vegetation fragments could potentially be restored as corridors and habitat for indigenous flora and fauna. We hypothesised that indigenous antelope maintained in a matrix of natural vegetation and abandoned field could play a role in restoration of Renoserveld via seed dispersal.We collected dung of indigenous ungulates in an abandoned field at various distances from natural Renosterveld vegetation, in order to assess the potential of large herbivores to contribute to restoration of plant diversity through seed dispersal. Emerged seedlings from the collected dung represented 29 forb, 13 grass, four sedge, four geophyte and one shrub species. The most abundant emerging seedlings were lawn grass Cynodon dactylon (38%), alien pasture grasses (31%) and indigenous geophyte Romulea rosea (12%). Whereas seeds of annual forbs and grasses were dispersed, only one shrub species was dispersed at very low density. We concluded that large herbivores could retard the rate of recovery of Renosterveld vegetation because viable seeds of herbaceous plants, particularly alien annual grasses and lawn-grasses were more abundant in the dung than the shrub, geophyte or perennial tussock grass species that characterise this vegetation type.     

延安北部丘陵沟壑区退耕还林(草)成效的遥感监测

将延安北部丘陵沟壑区的吴起、志丹、安塞、子长、延川、延长和宝塔等7县区做为一个整体,利用GIS综合解译分析SPOTVGT、NOAA/AVHRR、EOS/MODIS、TM和DEM数据,揭示该区域退耕还林(草)生态建设工程所取得的实效。1998-2009年NOAA/AVHRR和EOS/MODIS遥感监测表明,该区域在遥感影像图上凸现,在其北部和西部形成一条明显的与行政区边界相吻合的分界线,表明退耕还林后植被覆盖状况正在逐年改善,而且植被恢复情况明显好于其北部和西部。1999-2007年SPOTVGTNDVI演变表明,该区域NDVI正处于快速上升阶段,线性趋势值为0.0078,与其南部次生林区的NDVI差值在明显减小,与北部粮食种植区的NDVI差值在逐渐加大。退耕前后的TM影像解译结果对比分析说明,延安北部近年来退耕还林(草)的成绩是显著的,生态环境有了明显的改善。与1997年相比,到2007年延安北部有68.37%耕地不再耕种,而大于35°的坡耕地91.45%实现了退耕,25-35°的坡耕地有74.70%退耕,绝大部分高坡度耕地实现了退耕,而较低坡度的坡耕地退耕幅度也很大,达到了50%-70%。退出的耕地主要变为草地、林地和果园。TM影像解译结果表明,林草覆盖度增加非常显著,达到65.3%,增加24.3%,以草的面积增加最为明显。低植被覆盖度的土地面积在大幅度减少,植被覆盖度小于10%的面积减少了83.42%;中植被覆盖度面积在显著增加,到2007年,植被覆盖度在30%-50%的面积最大,占总面积的47.2%,将近一半;高植被覆盖度面积也明显增加,由1997年的6%增加到2007年22%。TM影像与DEM数据叠加分析表明,土壤侵蚀强度总体上降低,强度、极强度和剧烈等级土壤侵蚀的土地面积减少50%以上,但极强度和剧烈的高等级土壤侵蚀面积仍占2007年国土总面积的13.3%,土壤侵蚀状况仍然严重。植被以灌木和草为主,乔木面积较低,森林覆盖率只有22.4%,因此需要继续加强治理。     

桂西不同灌丛植物群落物种组成及其多样性

该研究通过野外设定样方、每木检尺的方法,调查了桂西9个市县的10种不同灌丛类型群落,分析了灌丛群落优势种重要值、物种组成、生长指标和物种多样性指数等生物学特征。结果表明：桂西灌丛资源丰富、分布广泛、类型多样,在调查的10个群落类型中,共有灌木树种87种,隶属于47科78属,以大戟科、蔷薇科和马鞭草科的树种较多;草本56种,隶属于31科48属,以禾本科、菊科和蔷薇科为主。灌丛群落主要分为灌木层和草本层,灌木层盖度为30％~70％,灌木的平均高度介于0.75~3.25 m之间,一般不超过5 m;草本层盖度为3％~90％,草本的平均高度在0.4~1.3 m之间,一般在1 m以下。不同灌丛群落的优势种重要值、物种多样性均不同,单优势种群落的优势种重要值普遍较高;而多优势种群落的物种多样性指数较高,即多优势种群落的物种数量多、分布均匀、结构更加复杂和稳定。物种丰富度S、多样性指数H′、优势度指数D和均匀度指数E之间存在显著的正相关性。综合分析,群落9(白栎＋马桑＋火棘灌丛)和群落10(黄荆＋灰毛浆果楝灌丛)的组成丰富、多样性水平较高。     

基于Google Earth Engine与机器学习的大尺度30m分辨率沙地灌木覆盖度估算

相较于降雨充沛的南方,中国北方沙地植被呈现覆盖整体偏低、空间异质性强的特点。灌木作为该区域的优势植被,对于风沙固定、食品/木材供给起着极为重要的作用。针对当前大尺度、中高分辨率干旱地区灌木覆盖度遥感产品缺失的现状,研究提出了一套通过Collect Earth样本收集器进行样本采集、利用Google Earth Engine遥感云平台的数据与计算优势开展大尺度灌木覆盖度估算的方法,并选取中国北方四大沙地之一的毛乌素沙地开展了示范应用。研究结果表明:(1)Collect Earth样本收集器可以有效地获取地面灌木覆盖度样本数据集,可以将灌木与高大乔木与草本植被进行有效区分,为灌木覆盖度估算样本集的建立打下了基础;(2)利用Landsat数据与其他辅助数据,机器学习算法可以较好地实现灌木覆盖度的估算,CART模型确定性系数R~2为0.73,均方根误差(Root Mean Square Error, RMSE)为13.66%,预测精度(Estimated Accuracy, EA)为61.8%,SVM模型R~2为0.72,RMSE为13.73%,EA为61.6%;(3)提出的基于GEE的灌木覆盖度估算体系可为我国乃至全球尺度干旱地区沙地灌木覆盖度信息提取提供有效支撑,具有较大的应用潜力。     

内蒙古温带典型草原围封十年草灌景观格局动态

通过样方调查和差分GPS法,研究内蒙古典型草原围封10年后灌木和草本盖度、生物量动态以及植被时空分布格局的变化。结果显示:草本盖度和生物量以2010年为拐点先减少后增加,灌木盖度和生物量呈现增加的趋势,样地整体植被生产力显著恢复。2010年以后,样地景观格局发生变化,小叶锦鸡儿灌丛斑块表现出破碎化程度和蔓延度先增加后减少的趋势。研究认为:(1)2012年之前为干旱期,草本生产力下降,且灌、草之间的竞争关系加剧了这一过程。(2)2012年之后降水增加,草本生产力先于灌木迅速恢复;景观尺度上小叶锦鸡儿灌丛斑块破碎化程度达到最高,是小叶锦鸡儿克隆生长的扩张过程所致。(3)2012年之后为湿润时期,小叶锦鸡儿对草本的生长存在促进作用,使生态系统逐渐恢复和重建。