新时期中华民族精神的培育

民族精神是一个民族赖以生存和发展的精神支撑。建设中国特色的社会主义现代化事业是一项前无古人的伟大创举 ,它更加需要一种积极向上的民族精神的支撑。培育新时期的中华民族精神是我们的一项重要任务 ,在培育民族精神的时候应该继承民族文化的优秀传统 ,吸收其他民族文化的优秀成分 ,同时又要使民族精神保持与时俱进 ,不断丰富和发展     

基于决策树的漓江上游土地覆盖分类

针对山区植被分类受地形复杂、植被类型多样、验证数据获取困难等因素限制基于多光谱数据的亚热带山区土地利用/覆盖分类存在困难,探究利用物候信息对亚热带山区植被实施分类的效果。综合运用归一化植被指数(NDVI)、比值植被指数(RVI)、归一化水指数(NDWI),同时考虑到海拔高度对植被类型的影响,建立决策树模型。该模型基于多时相Landsat TM影像,利用了不同地物类型的物候特征和光谱差异,将漓江上游地区分为8种土地覆盖类型。实验结果表明,分类结果总体精度达到86.40%,Kappa系数为0.83。     

天山新疆段植被物候特征及其气候响应

基于MODIS的MCD12Q2数据,采用趋势分析和相关性分析方法,结合遥感降水和气温数据产品,探求了天山新疆段2001—2014年植被物候的时空变化及其影响因素的相对作用。天山新疆段植被物候始期呈明显的垂直地带性分布特征,集中于3月10日至5月15日,全区14年平均值为3月20日;植被物候末期具有纬度地带性分布特征,集中于10月1日至10月25日。天山新疆段植被物候始期在山区呈不显著推迟趋势,绿洲和平原呈不显著提前趋势;植被物候末期主要呈不显著提前趋势;降水量和气温是影响天山植被物候期的重要因素。物候始期受当年春季气温的影响最为显著,也受到前一年冬季降水量的影响,其与降水量呈正相关,与气温呈负相关。夏季和秋季降水量是天山新疆段植被物候末期的主要影响因素。     

Comparison of eMODIS and MOD/MYD13A2 NDVI products during 2012–2014 spring green-up periods in Alaska and northwest Canada

Accurate monitoring of vegetation dynamics is required to understand the inter-annual variability and long term trends in terrestrial carbon exchange in tundra and boreal ecoregions. In western North America, two Normalized Vegetation Index (NDVI) products based on spectral reflectance data from the Moderate Resolution Imaging Spectroradiometer (MODIS) are available. The MOD/MYD13A2 NDVI product is available as a 16-day composite product in a sinusoidal projection as global hdf tiles. The eMODIS Alaska NDVI product is available as a 7-day composite geotif product in a regional equal area conic projection covering Alaska and the entire Yukon River Basin. These two NDVI products were compared for the 2012–2014 late May–late June spring green-up periods in Alaska and the Yukon Territory. Relative to the MOD/MYD13A2 NDVI product, it is likely that the eMODIS NDVI product contained more cloud-contaminated NDVI values. For example, the MOD/MYD13A2 product flagged substantially fewer pixels as “good quality” in each 16-day composite period compared to the corresponding MODIS Alaska NDVI product from a 7-day composite period. During the spring green-up period, when field-based NDVI increases, the eMODIS NDVI product averaged 43 percent of pixels that declined by at least 0.05 NDVI between 2 composite periods, consistent with cloud-contamination problems, while the MOD/MYD13A2 NDVI averaged only 6 percent of pixels. Based on a cloudy Landsat-8 scene, the eMODIS compositing process selected 23 percent pixels, while the MOD/MYD13A2 compositing process selected less than 0.003 percent pixels. Based on the results, it appears that the MOD/MYD13A2 NDVI product is superior for scientific applications based on NDVI phenology in the tundra and boreal regions of northwestern North America.     

羊栖菜受精卵/胚胎低温保存后的成活和发育

通过实验生物学方法,探讨了采用5℃条件保存的多细胞和两细胞状态羊栖菜(Hizikia fusiformis)受精卵的成活和发育情况。结果表明,相同保存和恢复培养条件下的羊栖菜受精卵,两细胞状态的死亡率明显高于多细胞状态。5℃条件保存60 h多细胞状态羊栖菜受精卵的死亡率均在10%左右,同样条件保存48 h两细胞状态受精卵死亡率高达75%。在异地运输羊栖菜受精卵或者胚胎完成苗种培育的过程中,应当同时考虑温度、运输时间以及受精卵的发育阶段等多个因素,才能取得比较好的实际效果。     

我国不同学科背景下GIS专业培养方案的比较研究

针对目前我国开设地理信息系统专业院校的学科背景比较复杂的情况,将所收集的30多所院校按学科背景分成地理类、测绘地图类、农林类、地质矿业类、建筑规划类和计算机类等6类,并分别从培养目标、培养要求、学制学位、核心专业课程和实践教学环节等方面比较了不同学科背景类的代表院校的专业培养方案.结果表明:不同学科背景下的GIS专业在培养目标和培养要求方面没有很大的区别,但在核心专业课程和实践教学环节方面则有较明显的差异,并在此基础上提出了一些促进GIS专业建设的想法.     

In-situ determination of sediment oxygen demand in cultivation ponds

ＩＮＴＲＯＤＵＣＴＩＯＮＳｅｄｉｍｅｎｔｏｘｙｇｅｎｄｅｍａｎｄ(ＳＯＤ)ｉｎｃｌｕｄｅｓｂｉｏｌｏｇｉｃａｌａｎｄｃｈｅｍｉｃａｌｏｘｙｇｅｎｄｅｍａｎｄ(ＧｅｏｒｇｅａｎｄＪｏｓｅｐｈ,1980),ｉｓａｎｉｍｐｏｒｔａｎｔｆａｃｔｏｒａｆｆｅｃｔｉｎｇｄｉｓｓｏｌｖｅｄｏｘｙｇｅｎ(ＤＯ)ａｎｄｈａｓｂｅｃｏｍｅａｎｉｍｐｏｒｔａｎｔｐａｒａｍｅｔｅｒｉｎｍａｎｙｗａｔｅｒｑｕａｌｉｔｙｍｏｄｅｌｓｆｏｒｃｕｌｔｕｒｅｐｏｎｄｓ(Ｍａｄｅｎｊｉａｎ,1990;Ｆａｎｇ,1991).Ｓｏｉｔｉｓｎｅｃｅｓｓａｒｙｔｏ…     

Analysis of differences in vegetation phenology cycle of abandoned farmland,using harmonic analysis of time-series vegetation indices data: the case of Gwangyang City,South Korea

ABSTRACT

Globally, countries have experienced substantial increases in farmland abandonment. Although vegetation phenology is a key factor for the classification of land use, understanding of the phenological change of abandoned farmland is lacking. Using harmonic analysis of NDVI and NDWI extracted from Landsat imagery, this study investigates the distinctive phenological characteristics of abandoned farmland, which contrasts with that of three other agricultural types (paddy, agricultural field, orchard) in the study site of Gwangyang City in Jeollanam Province, South Korea. The results suggest that abandoned farmland has higher overall greenness coverage and overall water content in vegetation than the other uses. In terms of both indices, abandoned farmlands changed with relatively less fluctuation than those of other uses, suggesting the existence of constant and unmanaged vegetation from ecological succession, which differs from crop fields that undergo cultivation procedures. The significant harmonic components differed among agricultural types and vegetation indices. In paddy, NDVI was explained with multiple, higher-order harmonic components, while in other types only first-order components met the 5% statistical significance level. With NDWI, land types were more clearly discernible, because of the different cultivation procedures involving water: wet-field method (paddy), dryland farming (orchard, agricultural field), and no cultivation (abandoned farmland). The analysis confirms that harmonic analysis could be useful in discerning abandoned farmland among areas of active agricultural use and shows that the statistical significance of harmonic terms can be employed as indicators of different agricultural types. The observed pattern of the geographic distribution of abandoned farmland has policy implications for the promotion of sustainable reuse of marginal farmland.     

Land surface phenology from VEGETATION and PROBA-V data. Assessment over deciduous forests

Land surface phenology has been widely retrieved although no consensus exists on the optimal satellite dataset and the method to extract phenology metrics. This study is the first comprehensive comparison of vegetation variables and methods to retrieve land surface phenology for 1999–2017 time series of Copernicus Global Land products derived from SPOT-VEGETATION and PROBA-V data. We investigated the sensitivity of phenology to (I) the input vegetation variable: normalized difference vegetation index (NDVI), leaf area index (LAI), fraction of absorbed photosynthetically active radiation (FAPAR), and fraction of vegetation cover (FCOVER); (II) the smoothing and gap filling method for deriving seasonal trajectories; and (III) the method to extract phenological metrics: thresholds based on a percentile of the annual amplitude of the vegetation variable, autoregressive moving averages, logistic function fitting, and first derivative methods. We validated the derived satellite phenological metrics (start of the season (SoS) and end of the season (EoS)) using available ground observations of Betula pendula, B. alleghaniensis, Acer rubrum, Fagus grandifolia, and Quercus rubra in Europe (Pan-European PEP725 network) and the USA (National Phenology Network, USA-NPN). The threshold-based method applied to the smoothed and gap-filled LAI V2 time series agreed best with the ground phenology, with root mean square errors of ˜10 d and ˜25 d for the timing of SoS and EoS respectively. This research is expected to contribute for the operational retrieval of land surface phenology within the Copernicus Global Land Service.     

中国东北地区植被生产力控制因素分析

植被生长季长度和生长强度是形态上影响植被生产力变化的重要因子。全球变暖情景下,北半球中高纬度大部分地区植被生长季显著延长并对植被生产力产生正向反馈,而植被生长强度变化情形及对生产力的控制作用并不清晰。中国东北地区属于中纬度温带地区,具有较高的植被覆盖度和丰富的植被类型,探索其植被生长季长度和强度的变化及对生产力的控制作用有利于理解和应对该地区的生态系统变化。以中国东北为研究区,基于1982—2015年长时序遥感植被指数数据（NDVI3g）,利用曲率求导法确定植被生长季开始点（SOS）、结束点（EOS）、生长季长度（LOS）和夏季最大生长季强度（GM）等关键物候参数,然后利用相对重要性（RI）方法定量分析了生长季长度和强度对植被生产力长期变化趋势的相对贡献及时空格局。结果表明：① 研究区整体的植被生产力和生长强度呈现增强趋势,而生长季长度呈现缩短趋势,导致生长强度成为控制生产力变化趋势的主要因素（RI = 70%）;② 在不同植被覆盖区域,生长季长度和生长强度对生产力的影响程度具有显著的空间差异。西部草原区植被生产力受生长强度控制最为显著（RI = 93%）,其次为针叶林（RI = 66%）和阔叶林区（RI = 62%）,农作物区生产力受生长强度影响最小（RI = 56%）。生长季长度对植被生产力的控制在农作物区最为显著（RI = 40%）,在其他区域的影响约为27%~35%。各植被覆盖区生长强度与生产力均为正相关,生长季长度与生产力均为负相关;③ 气候因素（降水、温度）和物候变化均对主要贡献因子生长强度产生影响,其中SOS的变化对生长强度的影响程度和空间范围最为显著,主要表现为SOS推迟促进生长强度增强。本研究基于遥感数据发现1982—2015年间中国东北地区植被生长更加旺盛,但是植被生长活动主要受生长强度的影响,该研究可以为植被生产力变化模拟的参数选择提供新的线索。