河龙区间植物措施因子定量计算

为解决区域植物措施(B)因子的计算问题,以河龙区间为研究区,通过计算半月降雨侵蚀力确定了主要侵蚀性降雨季,应用MODIS NDVI产品提取了半月植被覆盖度,得到侵蚀性降雨季植被覆盖度。根据已有研究成果,结合土地利用,计算了区域B因子,应用小区观测数据对植被覆盖度反演结果进行了检验。结果表明:反演与实测的植被覆盖度季节变化曲线变化趋势、值域范围基本一致。7—8月为主要侵蚀性降雨季,平均植被覆盖度达到57.23%,B因子平均值为0.345。年均降雨量与植被覆盖度成正比关系,与B因子成反比。该文采用的植物措施因子计算方法为区域土壤侵蚀监测提供参考。     

考虑地表粗糙度改进水云模型反演西班牙农田地表土壤含水率

土壤含水率是农业、环境、气象等领域进行建模的重要参数。该研究将微波遥感与光学遥感相结合,利用Sentinel-1数据交叉极化比及变换土壤调节植被指数对地表粗糙度进行估计,构建了一种改进的水云模型(modifiedwatercloud model, MWCM)。分析将NDVI、NDWI和NDWI1725,2200等植被指数作为植被冠层含水率时,水云模型(water cloud model,WCM)及MWCM农田地表土壤含水率的反演精度。结果表明:从总体精度上来看,MWCM的反演精度优于WCM。在不同植被覆盖度情况下:当植被覆盖度为中、低程度(NDVI0.5),MWCM具有较高的反演精度;在较高的植被覆盖度情况下(NDVI≥0.5),WCM与MWCM的反演精度较为接近。MWCM可有效的建立微波后向散射系数与地表土壤水分的关系,提高土壤含水率反演精度,为各种地表覆盖类型的土壤含水率反演提供研究思路及理论支持。     

基于像元二分模型的伏牛山地区植被覆盖度变化

植被覆盖度是反映区域生态环境的重要参数,研究植被覆盖度对评估区域生态环境质量具有重要意义。选用2000—2018年每年4—9月的MODIS NDVI数据基于像元二分模型对伏牛山地区逐月进行了植被覆盖度的反演,运用一元回归分析法,Hurst指数法,马尔科夫模型分析了伏牛山地区植被覆盖度的时空变化,并探究气象因子对植被覆盖度的影响。结果表明:(1)研究区植被覆盖较好,覆盖度的分布整体上呈现中间高,四周低的特点。(2)研究区内不同等级的植被覆盖度转化方式主要是由低水平覆盖度区向高水平覆盖度区的转化。(3) 2000—2018年研究区内有68%的地区其植被覆盖度呈增加趋势,表明近19年来伏牛山地区植被覆盖度整体呈上升趋势。(4)预计未来研究区内植被覆盖度呈减少趋势的地区占46%,呈增加趋势的地区仅占26%,由此可见伏牛山地区植被覆盖度未来的变化预计以减少为主。(5)伏牛山地区植被覆盖度的变化与气温和降水均呈现较强相关,其中气温是影响伏牛山地区植被覆盖度变化的主要因子。进一步分析该地区森林区域发现森林区域的植被覆盖度同样受气温的影响较大。     

基于NDVI的延河流域时空演变分析

利用8年的MODIS NDVI构建时序数据集,分析了延河流域2003—2010年植被覆盖度的时空格局和演变规律。借鉴时空数据分析模型,以栅格像元为分析单元,对该流域研究时段的绿度变换率进行计算分析,并利用像元二分模型对2003年和2010年地表植被覆盖度进行反演。结果表明:(1)延河流域植被生长状况总体呈改善趋势,延安南部林区、宝塔区东南部以及延长县中部植被覆盖较好且较稳定;(2)安塞县中南部、延长县大部以及杏子河中游的王瑶水库周边区域植被恢复效果显著;(3)在宝塔城区和城市重点开发区植被出现退化趋势。经分析,引起该流域局部植被退化主要是由于不合理的土地利用方式以及城市开发建设造成的植被破坏。基于像元的变化趋势分析更易于体现区域NDVI时空演变的细节信息。     

近20年黄土高原不同地貌类型区植被覆盖变化及原因分析

 植被覆盖是控制或加速水土流失最敏感的因子。以黄土高原为研究对象,利用1988—2005年NOAA/AVHRR植被指数(NDVI)月最大值合成的7月份资料分析不同地貌类型区NDVI值的时空变化规律,并通过计算NDVI值与同期降雨量的相关系数分析降雨量对不同地貌类型区NDVI的影响,探讨黄土高原典型区县退耕还林政策对NDVI的影响。结果表明:1)黄土高原整体植被覆盖度较低,NDVI多年平均值为0.29,平原区、石质山地、黄土低山、黄土塬及其周围地区NDVI值在0.30～0.40之间,梁、卯、片沙黄土丘陵区NDVI值在0.18～0.22之间,其余地貌类型区均低于0.15;2)1998年之后8年NDVI的平均值比前10年的NDVI平均值略有增加,整体增加幅度为4.5%,不同地貌类型区NDVI值变化表现出明显的地带性,呈东北西南走向,黄土高原主体部分中的黄土塬、黄土破碎塬、梁状黄土丘陵均增加10%以上,峁状黄土丘陵、风蚀沙化丘陵略有减少,减少的区域没有增加的区域大;3)除石质山地、黄土低山和平原地区外,其他地貌类型区7月最大NDVI值与5—7月累计降雨量存在很好的相关性,R2在0.60以上;4)地处梁状黄土丘陵区的吴旗县,1998年后形成了一个明显的以县为边界的NDVI值增长区,增幅达40%,远远高于该地貌类型区的平均增长值14%。初步结论:除平原地区外,降雨量决定黄土高原植被覆盖度的空间分布,1998年前后黄土高原植被变化的决定因素是降雨量;吴旗县的实例证明,只要水土保持资金到位、林草建设因地制宜、管理保护措施完善,退耕还林政策将会对植被覆盖度的增加起到积极作用。     

塔克拉玛干西部别里库姆沙漠NDVI时空变化特征

基于GIS技术和统计手段,利用GIMMS NDVI和MODIS NDVI数据集,并结合气温和降水0.5°×0.5°格网数据集,分析1981—2014年塔塔克拉玛干西部别里库姆沙漠NDVI时空变化特征。结果表明:(1)研究区NDVI半月值呈下降趋势,NDVI春冬季值整体为上升趋势,NDVI夏秋季值整体为下降趋势,NDVI年均值呈上升趋势;(2)1982—2014年NDVI值增加区域大于减少区域,整体上空间分布向南部移动,NDVI较大值主要在南坡和西坡;(3)植被覆盖度分布在0~0.004 3。     

基于NDVI象元二分法的植被覆盖变化监测

研究了NDVI象元二分法计算植被覆盖度的精度,并对其适用范围进行了分析。利用2002年、2007年合肥市的TM数据,针对于城市地区的特点,选择合适的NDVIsoil 和NDVIveg,计算各自时相的植被覆盖度,然后采用差值运算方法得到该时段合肥市区植被覆盖度变化数据。对于合肥市来说,在研究时段,植被覆盖度总体呈下降的趋势,下降最为明显的是滨湖新区和包河工业区,下降值分别为16.7%和21.4%,植被覆盖的锐减是由于城市扩张造成的,是一个值得注意的生态问题。与航片调绘结果进行比较,NDVI二分法得到的植被覆盖度对于低植被覆盖区偏高,对于高植被覆盖的林区偏低,两个时相植被覆盖度差值可以消除部分系统误差的影响,具有更高的精度,可以作为植被覆盖监测的重要手段。     

基于Sentinel-1A与Landsat 8数据的北黑高速沿线地表土壤水分遥感反演方法研究

土壤含水量是影响水文和气候变化的基本参数,研究土壤含水量分布,对气候变化、水资源分布、农作物估产等有着重要的现实意义和科学价值。本文以2015年6月21日的Sentinel-1A(哨兵1号)双极化合成孔径雷达影像为基础,结合同时段辅助光学影像Landsat 8,对北安—黑河高速沿线地区不同植被覆盖程度下复杂地表土壤含水量进行反演研究,探讨不同极化组合方式在不同土地利用方式下的土壤水分含量反演结果。结果表明:VH极化及VH与辅助变量NDVI(Normalized Difference Vegetation Index)组合反演精度分别为52.1%和53.6%,整体效果并不理想。VV极化(VV Polarization)图像和双极化VV/VH(VH Polarization)组合在裸露和低植被地区反演更具有优势,其精度分别为75.4%和59.5%,而在高植被覆盖度地区并不适用。VH极化反演结果中耕地土壤含水量比实际值低9.37%,VV极化在低植被区域土壤含水量比实际值低10.45%,在灌木及耕地地区VV/VH反演结果精度比单极化及其组合反演结果低,最高精度模型的反演是VV结合NDVI。VV与辅助变量NDVI结合能综合反映复杂地表环境下土壤含水量,其精度达84%,标准误差RMSE为2.07,比VV极化反演精度提高8.8%,RMSE比VV极化降低2.704。VV与辅助变量NDVI组合方式在中等植被覆盖地区土壤含水量反演更具有优势,并能够更好地发挥哨兵1号C波段合成孔径雷达在土壤水分研究中的潜力与有效性。     

基于遥感与GIS技术的水电站库区植被覆盖度动态变化分析

利用1988年TM图像和2003年ETM 图像,基于植被指数(NDVI),反演二滩库区米易县植被覆盖度,并借助GIS技术,对米易县1988-2003年植被覆盖动态变化进行分析.研究表明,研究区植被覆盖度变化与人类活动、自然因素有密切关系.其中二滩水库的蓄水作用对研究区生态环境变化产生重大影响,对植被覆盖度变化有重要意义.基于遥感技术进行库区植被覆盖度动态变化分析的研究思路和方法,将为水电开发生态环境影响的回顾评价提供重要的参考和借鉴.     

基于MODIS数据的北京市植被覆盖度动态监测

植被覆盖度是反映地表植被覆盖状况的重要指标,也是衡量区域环境质量与水土保持情况的重要因子。以北京市为研究区域,应用基于MODIS NDVI的像元二分模型估算北京市2014—2016年植被覆盖度,分析不同年份、不同分级植被覆盖度的变化情况,结果表明:北京市植被覆盖度整体较高,高植被覆盖度区域在全市范围占了很大的比例,山区植被覆盖度明显高于平原区;植被覆盖状况总体较为稳定,呈现改善趋势,低植被覆盖度、中低植被覆盖度、中等植被覆盖度、中高植被覆盖度面积连续2年均出现了不同程度的减少,其覆盖度等级逐渐向高植被覆盖度演进。     

Transformation of the Bryansk Paleosol in Microdepressions in the Center of the East European Forest-Steppe during the Maximum of Valdai Glaciation and in the Holocene

Eurasian Soil Science - Recent and Late Pleistocene soils of the central forest-steppe in the East European Plain have been studied. The main objective of the work is to reveal changes in the...     

Changes in the structure of the rhizosphere complex of actinomycetes in the ontogenesis of winter rye

Changes in the taxonomic structure of actinomycetes in the rhizosphere of winter rye (Secale cereale L.) growing on acid soddy-podzolic soil were studied. During the first stages of ontogenesis of winter rye, the rhizosphere complex of mycelial prokaryotes was characterized by a relatively level generic structure (with respect to the indices of abundance and frequency of particular genera), low values of the species diversity, and low domination frequency of the species from the Streptomyces genus. The numbers and species diversity of the streptomycetes increased during the further growth of the winter rye, so that streptomycetes became a dominant group in the complex of the rhizosphere actinomycetes. According to the two-way ANOVA, the population density of the Micromonospora and the Streptosporangium genera in the rhizosphere was mainly dictated by the winter rye variety, whereas the population density of the streptomycetes depended on the particular stage of the winter rye development. The differences between the actinomycetal complexes characteristic of different varieties of winter rye at the early stages of its development was leveled by the end of the winter rye growth.     

Evolution of forest pedogenesis in the south of the forest-steppe of the Central Russian Upland in the Late Holocene

The Late Holocene stage of forest pedogenesis has been studied on the interfluves along river valleys in the forest-steppe zone of the Central Russian Upland. The development of gray forest soils from the former chernozems as a result of the Late Holocene advance of forest vegetation over steppes is discussed. It is argued that the climatic conditions of the Subatlantic period were unstable, so that multiple alternation of forest and steppe vegetation communities took place. This specified a complex character of soil evolution upon contrasting substitution of forest pedogenesis for steppe pedogenesis. On the interfluves near the natural drainage network (balkas, ravines, and steep slopes of river valleys), the climate-driven dynamics of forest and steppe vegetation with corresponding changes in the character of pedogenesis could take place during the entire Holocene, which is reflected in a lower thickness of humus profiles and deeper leaching of carbonates from chernozems of the Early Iron Age in comparison with their analogues formed under steppe cenoses in central parts of the interfluves. Two variants of the evolution of gray forest soils can be suggested: the pulsating evolution typical of balkas and interfluves near river valleys and the continuous progressive evolution typical of automorphic (plakor) positions in central parts of the interfluves.     

Accumulation of chemical elements in the raised peatbogs of the subtaiga Trans-Urals in the Holocene

The results of studying the variability of the geochemical parameters of the layers of the Sartamskii upland peatbog in the south of Tyumen oblast based on the radiocarbon time scale are given. Four basic types of peat and stages of peat deposits formation in the Holocene are distinguished: the organomineral layer of the sediments in a paleolake (up to 5065 ± 60 years ago), the low moor layer (4300–4900 years ago), the transitional layer (3100–4300 years ago), and the high moor peat (250–3100 years ago). The upper peat layer (last 200–300 years) significantly differs from its main portion; in particular, it is characterized by an increased ash content and the accumulation of a number of elements. The relationship between the various characteristics of the deposit is analyzed using principal component analysis, and the conditions of the formation of the peat deposit in different time periods are estimated, including the climatic conditions (in relative units). The anthropogenic signal of the accumulation of some elements in wetland systems is identified.     

论图书馆数字馆藏资源建设中亟待解决的问题

论述数字馆藏的产生、概念和特点,分析数字馆藏资源建设中存在的问题,探讨数字馆藏资源建设中应采取的策略。     

Variations in the composition of the sap of zea mays with the increase in osmotic pressure of the nutritive solution

The alterations are studied which are produced in the content of mineral elements and organic fractions of sap with the increase in the osmotic pressure of the nutritive solution at levels of 2.0; 3.5 and 5.0 atm., obtained through the addition to the nutritive solution either of magnesium sulphate or PEG‐4000.

Through the effect of the osmotic pressure, the transformations are modified of the nitrogen and mineral phosphorus at organic fractions experience a series of modifications which produce different values in the Nm%TSN and Pm%TSP ratios with respect to control. Through action of the specific effect of magnesium sulphate, the reducing sugars concentrations in sap having an important increase.     

Seasonal changes in the communities of microorganisms and algae in the litters of tree plantations in the steppe zone

Specific structural and dynamic parameters of communities from various ecological and trophic groups of microorganisms and algae in the litter of artificial tree stands were studied using the example of the Staro-Berdyansky Forest in the steppe zone of Ukraine. The composition of the communities was shown to vary by seasons and depend on the forest-forming woody species. In spring, in all the litters, the maximal number of actinomycetes and aminotrophs was recorded; in the leaf litter, the number of phosphate-mobilizing organisms was also the largest. In summer, the development of cellulolytic organisms, ammonifiers, and nitrogen-fixers was intensified; in autumn, the number of micromycetes and oligotrophic organisms decreased. The composition of dominants, the species richness of algae and their abundance also varied by seasons. Representatives of the Chlorophyta division predominated. The highest species richness of algae was characteristic of the spring litter samples, and their number, for the spring and autumn ones. The positive correlation was established between the numbers of micromycetes and oligotrophs, micromycetes and algae. The negative correlation was found between the numbers of micromycetes and actinomycetes, cellulose-decompose bacteria and algae in the litters.     

Changes in the physical properties of soils in the Kamennaya Steppe under the impact of shelterbelts

The physical properties of ordinary chernozems and meadow-chernozemic soils under different land management practices (maple, larch, birch, and pine sections of the shelterbelts; continuous (since 1959) fallow; and arable field (since 1952)) were studied in the Kamennaya Steppe. The soils had favorable physicochemical properties, light clayey texture, and high microaggregation independently from the type of land management. The long-term impact of the shelterbelts improved the soil structure in the upper part of the humus horizon: the content of agronomically valuable aggregates increased, the content of coarse aggregates (>10 mm) decreased, the aggregation coefficient increased by 3.7–4.3 times, and the water stability of the aggregates became by 8–12% higher. The soils under the shelterbelts were characterized by minimum values of the bulk density and solid phase density and by maximum values of the total, active, and air porosities. At the same time, no considerable differences between water reserves in the studied range of soils were detected. The ratio of the optimum productive water range to the active (productive) water range (OPWR/AWR) within the upper soil meter varied from 0.42–0.44 to 0.45–0.54. This points to changes in the character of perched water: the content of intra-aggregate capillary-perched water decreases, and content of film perched water increases down the soil profile.     

近50年博斯腾湖水位变化特征分析

以干旱区博斯腾湖为研究对象,依据博斯腾湖1956—2012年期间的水位监测数据,采用小波分析及MannKendall(M-K)趋势检验等统计学方法,揭示了近50a博斯腾湖水位变化趋势及规律。结果显示:博斯腾湖1956—2012年水位变化分为3个阶段下降(1956—1987年)—上升(1988—2002年)—下降(2003—2012年),其中1956—1987年水位下降了3.39m;1988—2002年上升了3.7m;2003—2012年再次下降了3.21m。水位总体上呈现出显著的下降趋势,且通过了α=0.05时的显著性检验。就其周期性变化规律而言,博斯腾湖水位存在18a的主周期,而38a的周期由于水位资料序列有限难以确定,需要更长的资料序列进行分析验证。     

Quality of used-snow discharged in the ST-Lawrence river,in the region of the Montreal Harbor

Snow disposal creates problems each year in Montreal. Snow dumping in water courses is favored due to both esthetic and economic considerations. Used snow must be considered as a potential pollutant. Its impact on the aquatic receiving environment is not well known. With river dumping in progress, snow samples were collected at 3 sites: Concorde Bridge, and at piers 30 and 52 in Montreal Harbor. Analysis of 28 routine parameters demonstrated that the quality of snow ultimately dumped in the river varies considerably according to its sources and the time it remains in the streets. Used-snow from residential areas was shown to be less polluted than the snow from commercial areas. Furthermore, from the total number of sampled districts, used-snow dumped at pier 30 appears to be relatively more polluted as it originated from downtown areas where vehicle circulation is more dense. Heavy metals in particles sizes between 0.45 and 63 μm represented more than 70% of the measured suspended solids which reflects the risk of bioaccumulation via benthic organisms. Principal component analysis of present data suggests that with analysis of chlorides, suspended solids and Pb alone, it is possible to approximately determine the quality of used-snow.