The effect of land cover/vegetation on soil water dynamic in the hilly area of the loess plateau,China

Severe soil and water loss has lead to widespread land degradation in China's loess plateau. During the past decades, a great deal of effort was made on vegetation restoration to reduce soil and water loss in the loess plateau. However, due to water shortage the efficiency of vegetation restoration was not as satisfactory as expected. As part of a vegetation restoration project, we conducted research aiming to understand the relationship between vegetation pattern and soil water dynamics. The goal was to find vegetation types appropriate for the loess plateau with scarce water resources. In 1986, fifteen plots of land were planted with five vegetation types: pine woodland, shrubland, sloping cropland, alfalfa and semi-natural grassland. Soil water content, runoff, soil erosion were measured for each plot. Environmental variables, such as rainfall, evaporation and temperature, were recorded simultaneously by an automated meteorological station. The relationship between land cover pattern and soil water dynamic was evaluated by using statistical models. We found that: (1) soil water loss occurred during the growing season, and it reached the maximum in the second half of July; (2) soil water was not fully replenished from rainfall during the rainy season; (3) pine woodland induced the largest water loss to surface runoff, followed by sloping cropland, alfalfa, semi-natural grassland and shrubland; the poor capability of pine woodland for water conservation may be attributed to soil compaction and poor ground coverage under the tree; (4) in most cases, soil water of the five vegetation types was low except for shrubland and semi-natural grassland where it was moderate-high during a few periods. These conditions inhibit sustainable vegetation growth in the semi-arid loess hilly area of the loess plateau, China.     

黄河三角洲冲积平原湿地土壤酶活性与养分相关性研究

对黄河三角洲冲积平原湿地酶活性与土壤养分相关性做了研究.结果表明:随着离海距离的增加,土壤有机质及各养分表现出有规律的变化,土壤脲酶、过氧化氢酶活性沿湿地演替的方向活性升高,过氧化物酶活性降低.土壤有机质和各养分与酶活性相关性达极显著和显著水平,不同土壤酶活性之间也有显著的相关性.3种酶可以作为评价黄河三角洲冲积平原湿地土壤肥力的指标.     

温度对煤矸石山水分及植物生长的影响——以山西省阳泉市煤矸石山为例

 采用野外调查试验、取样和室内分析的方法,研究煤矸石山温度对水分及植被生长的影响。结果表明:煤矸石山温度在垂直方向随着深度的增加有上升趋势,与自然黄土荒坡变化趋势相反,且覆土后的煤矸石山较自然恢复煤矸石山温度变化剧烈;在垂直0～80cm的范围内,自然恢复、覆土50 cm和覆土100cm煤矸石山相邻土层（10cm）温度升高值分别为0.68、2.20和2.97℃;覆土煤矸石山水分含量在垂直方向因温度升高逐步下降,其水分含量较自然恢复煤矸石山平均高出10%～15%;在山西省阳泉市煤矸石山适宜生长的耐高温植物有灰绿藜、茵陈蒿、蒺藜、马齿苋、臭蒿、狗尾草、沙打旺和鬼针草,4种植物对温度敏感程度由高到低依次为紫穗槐>刺槐>臭椿>侧柏。     

草地覆盖坡面流水动力参数的室内降雨试验

为研究两种典型黄土的坡面流水力特性变化规律,进行了室内人工降雨试验。以草地盖度为主要影响因子,土壤质地和雨强为辅助影响因子进行分析。结果表明:同一盖度下,随雨强逐渐增大,流量和流速也随之增加;当盖度增加时,流量和流速随之减小。流速随降雨历时的延长而逐渐增大;当雨强增大时,流速曲线整体抬高;当覆盖度逐渐增大,流速曲线整体降低。平均水深随流速增大而减小;同一雨强下,盖度增加时氟汝德数Fr随之增加,雷诺数Re降低,而Darcy-Weisbach阻力系数f及曼宁粗糙系数n均大致呈增加趋势;对同一盖度,雨强增加Fr随之减小,Re逐渐增加,同时f和n均随之减小。因此草地覆盖度增加将改善坡面流水力性质,总体上减小了坡面流速,增加了阻力和粗糙度。     

基于无人机遥感与随机森林的荒漠草原植被分类方法

荒漠草原是草原中最旱生的类型,属于草原的极限生态状态,也是气候变化和生态系统演变的预警区。利用无人机高光谱遥感技术快速、准确地提取荒漠草原草地植被类型,对动态监测草原生态安全和合理开发草地畜牧业具有重要意义。以无人机搭载高光谱成像系统采集内蒙古荒漠草原遥感图像,获得具有高空间分辨率和高光谱分辨率的图像;通过光谱连续统去除变换,增强草地植被之间的光谱差异,并构建植被指数;采用分步波段选择法选择荒漠草原植被的特征波段,实现高光谱数据降维;构建融合光谱特征、植被特征、地形特征和纹理特征等24个变量的随机森林分类模型,并与支持向量机（SVM）、K-最近邻（KNN）和最大似然分类（MLC）法进行比较。结果表明,在4种分类方法中随机森林分类算法分类效果最好,总体分类精度达到91.06%,比SVM、KNN和MLC等机器学习算法分别高7.9、15.61、18.33个百分点,Kappa系数达到0.90,比SVM、KNN和MLC算法分别高0.13、0.23和0.26。无人机高光谱低空遥感和随机森林算法的结合为荒漠草原草地植被分类提供了新途径。     

准噶尔盆地绿洲-沙漠过渡带植被时空演变特征

通过对准噶尔盆地绿洲-沙漠过渡带的植被种群和覆盖度的调查,以及1989年和2000年两期TM影像景观格局的解译,运用时间动态度和Ripley's K函数的方法分析了准噶尔盆地绿洲-沙漠过渡带植被的时空变化特征.结果表明,1989～2000年,研究区内人为垦地幅度较大,农田面积增加,而天然植被区域被垦地利用或破坏,造成植被面积减少,总的覆盖度降低,同时沙化面积加大.     

扬州瘦西湖公园绿地空间格局与结构的量化研究

采用遥感图像判读和野外调查相结合的方法,定量分析扬州瘦西湖公园绿地的空间格局及植物群落的物种结构。结果表明:扬州瘦西湖公园共有绿地斑块230个,而斑块形状指数Ips≥1.50的绿地斑块为105个,绿地斑块形状受人为干扰程度较大。绿地景观类型较多,多样性指数较高。植被的生长状况良好;物种丰富,其中垂柳、桃、意杨、枫杨在树木株数和相对优势度上均占优势;植被在高度和胸径上的分布均表现为具有向上发展的潜力,属于发挥生态效益的最佳时期。扬州瘦西湖公园的树种多度与基于叶面积的相对优势度之间无明显关联,数量上占优势的树种,其相对优势度不一定很高。植被树木株数与不同树高等级间的分布关系表现为随着树木高度级的增加,树木株数相应减少;树木株数分布与不同胸径等级间的关系也呈现类似的情况。     

印榕仙人掌的资源价值及开发利用

概述了印榕仙人掌的食用与药用价值,并对印榕仙人掌植被恢复功能和饲料用途进行了介绍。针对我国仙人掌发展的现状,重点论述了印榕仙人掌在胭脂虫培育利用方面的重要性。并从印榕仙人掌的保健功能、胭脂虫培育以及植被恢复重建开发利用等方面提出建议。     

基于地表高光谱与OLI影像的土壤含盐量和pH值估测

针对宁夏银北地区大面积土壤盐碱化监测的需要,利用实测植被冠层光谱与Landsat 8 OLI影像相结合进行土壤含盐量和pH值估测研究.对实测植被冠层高光谱与影像多光谱反射率进行倒数、对数、三角函数及其一阶微分等一系列变换,确定最佳光谱变换形式,筛选敏感植被指数和敏感波段,分别建立基于实测植被光谱与Landsat 8 O...