Vegetation fractional coverage change in a typical oasis region in Tarim River Watershed based on remote sensing

Vegetation fractional coverage(VFC) is an important index to describe and evaluate the ecological system.The vegetation index is widely used to monitor vegetation coverage in the field of remote sensing(RS).In this paper,the author conducted a case study of the delta oasis of Weigan and Kuqa rivers,which is a typical saline area in the Tarim River Watershed.The current study was based on the TM/ETM+ images of 1989,2001,and 2006,and supported by Geographic Information System(GIS) spatial analysis,vegetation index,and dimidiate pixel model.In addition,VBSI(vegetation,bare soil and shadow indices) suitable for TM/ETM+ images,constructed with FCD(forest canopy density) model principle and put forward by ITTO(International Tropical Timber Organization),was used,and it was applied to estimate the VFC.The estimation accuracy was later proven to be up to 83.52%.Further,the study analyzed and appraised the changes in vegetation patterns and revealed a pattern of spatial change in the vegetation coverage of the study area by producing the map of VFC levels in the delta oasis.Forest,grassland,and farmland were the three main land-use types with high and extremely-high coverage,and they played an important role in maintaining the vegetation.The forest area determined the changes of the coverage area,whereas the other two land types affected the directions of change.Therefore,planting trees,protecting grasslands,reclaiming farmlands,and controlling unused lands should be included in a long-term program because of their importance in keeping regional vegetation coverage.Finally,the dynamic variation of VFC in the study area was evaluated according to the quantity and spatial distribution rendered by plant cover digital images to deeply analyze the reason behind the variation.     

水肥耦合对黄河三角洲盐碱地小麦根系形态和分布的影响

[目的]为了探索黄河三角洲轻度和中度盐碱地小麦根系分布情况,分析水肥耦合对小麦的根系分布的影响。[方法] 设置不灌水,灌底墒水,灌底墒水和拔节水,灌底墒水、拔节水和灌浆水4种灌水方式;不施肥,施有机肥,施有机肥与无机复合肥和施无机复合肥4种施肥方式,探索不同水肥耦合条件下黄河三角洲盐碱地小麦根系形态和分布情况。[结果]结果显示,盐碱地小麦根系主要集中在0-30cm土层,且随着土层的加深逐渐减少。在本文中,各根系形态指标之间表现为极显著的正相关关系。灌水次数和施肥种类对小麦根系的生长发育有重要影响,灌2次水,施无机复合肥处理的小麦根系活力最高,根系形态最好。[结论]因此,在黄河三角洲轻度和中度盐碱地,小麦根系分布主要集中于前30 cm,拔节水和无机复合肥有利于促进小麦根系发育,可获得较好的根系形态结构。     

珠江三角洲网河区顶点河道断面侵蚀形态的演变

[目的]研究断面形态的演变特征,给上游来水来沙、人类活动影响的分析提供检验,也为下游水文地貌的演变提供科学依据。[方法]利用珠江三角州网河区三水站和马口站资料,通过提取反映河道断面侵蚀形态的指标,采用模拟退火算法优化的投影寻踪模型,综合解析河道断面侵蚀形态的演变特征。[结果]由于三水站2009年的虚实比远大于其他年份的虚实比,2009年三水站断面侵蚀形态异于其他年份外,其他年份侵蚀形态的变化较为缓和;对于马口站而言,尽管该断面的侵蚀形态变化较多,但综合5项反映河道断面侵蚀形态指标来看,该断面形态的变化类型总体上可以划分成2种侵蚀类别。[结论]总体上,21世纪初马口和三水站断面比20世纪90年代过水断面增大,断面的过水能力有加大的趋势。     

Environmental influences on Atlantic bluefin tuna (Thunnus thynnus) catch per unit effort in the southern Gulf of St. Lawrence

The Atlantic bluefin tuna (Thunnus thynnus) population in the western Atlantic supports substantial commercial and recreational fisheries. Despite quota establishment and management under the auspices of the International Commission for the Conservation of Atlantic Tunas, only small increases in population growth have been estimated. In contrast to other western bluefin tuna fisheries indices, contemporary estimates of catch per unit effort (CPUE) in the southern Gulf of St. Lawrence have increased rapidly and are at record highs. This area is characterized by the Cold Intermediate Layer (CIL) that is defined by waters <3°C and located at depths of 30–40 m in September. We investigated the influence of several in situ environmental variables on the bluefin tuna fishery CPUE using delta‐lognormal modelling and relatively extensive and consistent oceanographic survey data, as well as dockside monitoring and mandatory logbook data associated with the fishery. Although there is considerable spatial and temporal variation of water mass characteristics, the amount of available habitat in the southern Gulf of St. Lawrence (assuming a > 3°C thermal ambit) for bluefin tuna has been increasing. The percentage of the water column occupied by the CIL was a significant environmental variable in the standardization of CPUE estimates. There was also a negative relationship between the spatial extents of the CIL and the fishery. Properties of the CIL account for variation in the bluefin tuna CPUE and may be a factor in determining the amount of available feeding habitat for bluefin tuna in the southern Gulf of St. Lawrence.     

渭干河-库车河三角洲绿洲棉花种植面积时空变化特征分析

利用研究区棉花种植面积和产量相关统计数据,探究研究区棉花种植面积和产量的时空变化特征及单产和面积作用对棉花产量的影响。研究结果表明：(1) 近62年来,研究区的棉花种植面积、棉花产量和单产均呈上升趋势,而且表现出明显的阶段性和波动性,1949—1985年间增长缓慢,1986—2011年增长迅速。(2) 就棉花总产波动来看, 单产的作用占42.04%,面积作用占50.96%,在1949—1985年间单产增加对棉花总产量提高的贡献较大,在1986—2011年间棉花种植面积扩大对棉花总产量提高的贡献较大。(3) 1985年前棉花种植面积较稳定,波动不大,主要靠挤占粮食作物面积来扩大,1986年之后棉花种植面积扩大迅速,主要途径为开荒造地。(4) 棉花市场价格的波动、生产成本的上升、产量的徘徊、生产环境的恶化和品种等直接影响着研究区棉花生产的竞争力和棉农增收。     

渭干河--库车河三角洲绿洲近50a来生态环境变化特征及防治对策

近 5 0年来 ,渭干河—库车河三角洲绿洲地区在人类不合理活动的作用下 ,水文与生态环境发生了一系列变化。1绿洲地表径流总量多年变化有增有减呈现波动性趋势 ,但是水体盐化和含沙量趋势加剧。2绿洲森林面积持续减少 ,其天然屏障作用减弱 ,草地面积减少、退化严重 ,载畜能力大大降低。 3土地退化面积扩大 ,土地沙漠化发展强烈 ,土壤肥力降低 ,生产能力下降。因此 ,进行水资源统筹利用规划与管理 ,统筹兼顾各县的经济发展与生态环境建设对水的需求 ,以生态系统健康发展为原则 ,遵循生态规律来进行土地资源的开发利用 ,开展整个绿洲为单元的生态功能保护与建设是提高绿洲可持续发展能力的根本途径     

辽河三角洲水稻纹枯病菌丝融合群测定

辽河三角洲是辽宁省水稻主产区,水稻纹枯病近年来持续严重发生,本研究对辽河三角洲稻区的不同水稻品种上分离获得的纹枯病菌菌株进行融合测试,以便探明水稻品种来源各异的病菌菌群类别及其分布的关系,研究探讨辽河三角洲水稻纹枯病菌菌丝融合群构成,为生产上病害流行、预测以及针对性进行水稻品种选育和推广应用,提供理论基础。     

蒸汽后处理对ACQ-D处理杉木中铜的抗水流失性的影响

该文考察了蒸汽后处理对ACQ-D处理材中有效成分铜的抗水流失性和化合价转变的影响,并通过SEM及FTIR谱图,对铜与木材组分间的固着反应及产物进行了分析。结果表明:与直接进行流失试验的ACQ-D处理材相比,蒸汽后处理可以在15 min内就明显降低铜的流失率,处理时间和蒸汽温度对铜的流失率影响较小。与气干处理材相比,蒸汽处理对试材中铜的化合价转变影响不大,因此可确保蒸汽后处理不会削弱ACQ-D处理材的耐腐性,但也无法生成更多抗流失性较好的一价铜离子化合物。SEM及FTIR谱图显示:蒸汽处理促进了铜胺溶液与木材间的反应,生成了大量晶体颗粒附着在木材细胞壁表面;铜在处理材中的固着反应场所主要是半纤维素和木素中的羧基、酚基、羰基及醚键。     

动词基本结构的建立及对汉语句子英译的意义

对题元角色的把握,有助于确定抽象句子中动词的配价情况以及空语类,进而建立起类的、潜在的、静态的、抽象的、具有概括性的动词基本结构（深层结构）。反过来,动词基本结构的建立,可以指导我们把握具体语句的题元角色、动词配价和空语类,有助于把握动词结构各种动态的、具体的变式（表层结构）。动词基本结构的建立对汉语句子的英译有着重要的指导意义。     

黄河三角洲湿地植被研究现状及存在的问题

对黄河三角洲湿地植被的研究现状进行了综述,指出研究技术与手段不断提高、研究内容不断深入是三角洲植被研究的特点,系统定位研究、“3S”等新技术应用及植被群落演替是现今研究存在的不足,也是今后的主要发展方向。