基于TM影像的盐城市土地利用时空变化研究

为了探讨海岸带土地资源动态变化,为生态环境保护提供依据,笔者以盐城市为例,利用1992年、2002年2期TM影像,采用最大似然法进行监督分类,解译出不同时期的土地利用图。并基于GIS的空间分析功能,分析了盐城市土地利用类型变化的时空特征和规律。采用单一土地利用动态度来描述各种土地利用类型的变化速度。同时,基于统计年鉴分析了研究区土地利用变化的社会经济影响因素。结果表明：耕地和滩涂是面积减少最多的土地利用类型。耕地主要转化为林地、水域、建设用地和园地,而滩涂主要转化为盐田、养虾池等水域类型。建设用地是面积增加最多的类型,增加速度也最快,其主要转入来源为对耕地的占用。盐城市的土地利用变化是由人口的增长、政府规划与决策以及城市化的发展等因素综合作用的结果。研究区土地利用的变化特征不利于区域可持续发展,威胁到野生生物的生存环境,需要进行宏观调控和科学管理。     

漓江上游山区复杂地形水热通量的时空变化规律

为了估算漓江上游农林经济的发展对决定地表微气候环境的水热通量的影响,计算山区复杂地形影响下的地表太阳辐射以改进SEBAL模型,提出归一化水热通量使不同时相具有可比性,对漓江上游1989-2006年5景TM/ETM卫星图像利用改进模型反演水热通量。结果表明,在空间上随植被覆盖度的增加,显热通量降低而潜热通量增加,植被覆盖度在0.2～0.7时的影响非常显著。1989-2000年植被覆盖度均值明显降低,而2000-2006年逐渐上升,导致波文比(显热与潜热比)均值明显升高然后逐渐降低,归一化潜热数值较高的像元比例减少然后增加,归一化显热数值较高的像元比例增加然后减少。尽管在2006年植被覆盖度均值接近于1989年,但波文比均值仍明显高于1989年。研究区经济林、旱地农作物面积的增加,阔叶林面积减少,水源林的减少与退化,导致了显热与潜热比平均值的升高。     

科尔沁地区不同类型沙地土壤水分的时空异质性

应用半干旱区科尔沁沙地2006-2010年5-9月份土壤水分定点观测资料,研究农田、沙质草地和固定沙丘土壤水分的时空变异性。结果表明:2006年5月-2010年9月,(1)农田、沙质草地和固定沙丘土壤水分都在7月份最高;农田7月份土壤水分与5、6月份的差异显著,沙质草地7月份的与8、9月份的差异显著,而固定沙丘7月份的与生长季其他月份的都有显著差异;(2)3个样地土壤水分随年份有逐渐增加的趋势;(3)农田、沙质草地和固定沙丘0-160cm平均土壤含水量分别为20.69%,7.63%,3.61%,农田土壤水分明显高于沙质草地和固定沙丘,而且3种样地间土壤水分差异显著;(4)3个样地土壤水分随土层厚度增加呈"先增加后减少,最后又增加"的趋势;农田0-20cm土壤水分与20-40cm,40-60cm,120-140cm及140-160cm的差异显著;沙质草地0-20cm土壤水分除与140-160cm有显著差异外,与其他土层均无显著差异;固定沙丘土壤水分只有100-120cm与140-160cm的差异显著;(5)研究区降雨的季节分配极不均匀,主要集中在4-10月的生长季,占全年降雨量的92.58%;0～5mm降雨占全年降雨事件的73.29%,但其降雨量只占全年降雨量的25.1%;降雨间隔期以0～10d为主,占全年无降雨期的37.6%;0～10d降雨间隔期出现的频数最高,占全年间隔期频数的86.9%;(6)当土壤水分较高时,其变异性会随着土壤水分的增加而减小,而当土壤水分较低时,其变异性随土壤水分的增加而增加。     

华北平原潮土速效N、P、K的空间分布及时间变化

通过2000、2002年田间定点试验,研究了华北平原潮土土壤碱解氮、速效钾、有效磷含量在空间上的分布和时间上的变化及其对农作物的产量效应。结果表明,我国华北地区土壤碱解氮含量水平稳中有升;速效钾含量水平较高,但有递减的趋势;有效磷含量水平很低,但空间变异性较大,制约了作物的增产。研究表明传统的施肥方法很难改善土壤养分的空间变异结构,甚至会使土壤养分水平更加不平衡,只有根据土壤养分的丰缺状况,有针对性地实施精准施肥和科学管理,才能改善土壤养分的空间分布。     

2000-2017年中国农村水资源贫困与经济贫困的耦合协调状态及其影响因素

[目的] 测算中国农村水资源贫困指数和经济贫困指数的耦合度和耦合协调度,为减轻农村水贫困与经济贫困提供理论依据和政策启示。[方法] 以中国31个省（市、区）为研究对象,运用层次分析法、熵值法、系统耦合协调度模型、空间杜宾面板数据模型等方法,研究了2000—2017年农村水资源贫困与经济贫困耦合协调度的时空分布特征和影响因素。[结果] ①从整体来看,虽然中国农村水资源贫困与经济贫困的耦合协调度不高,但大致呈上升趋势,且中国31个省（市、区）均表现为耦合度大于耦合协调度。②就空间角度而言,中国农村水资源贫困与经济贫困的耦合协调度呈现由东南部向东北、西南部扩散的态势,东部沿海地区的江苏和浙江、南部沿海地区的福建与广东、地处长江中游地带的湖南省的耦合协调度最高。③农村水资源贫困与农村经济贫困耦合协调程度存在明显的负向溢出效应。财政农林水事务支出对农业生产具有较大的促进作用,而农产品价格和第二、三产业比例提高会抑制其发展。[结论] 国家应加大或维持对农村原有的财政支持力度,充分发挥政府和市场在资源配置中的调节作用。合理调整农产品价格的同时,加大农业技术投入,加强地区间分工合作,促进产业升级,从而推保农村水资源与农村经济协调发展。     

Determinants of parr size variations within a population of brown trout Salmo trutta L.

Abstract – The size of 2-month old trout Salmo trutta parr differed between sites and between years along the River Esva catchment (Asturias, northwestern Spain). Such variation was in a direction opposite to the variation observed in parental size. Parr were smaller in sites where parents grew faster, whereas larger parr occurred in sites where parents grew less. Parr size of six cohorts (1990–1996, except 1995) at 14 sites along the River Esva was inversely related to the growth rate and length of parents and positively related to canopy, egg size, and water temperature. The latter acted similarly on all parr independently of egg size and the site where the egg originated. Covariation patterns among parr size, parental traits, and canopy suggest that a canopy-regulated, growth-determined trade-off between egg size and number, previously described for the Esva trout, also extends to alevin size. In forested, shaded sites, adult trout grew less and spawned fewer larger eggs that resulted in larger alevins, whereas in fully insolated, production-rich sites, trout grew faster and spawned higher numbers of smaller eggs that produced smaller parr. I hypothesize that the phenotypic plasticity illustrated by the environmentally induced trade-off between egg size and number further extended to alevin size may be evolutionarily advantageous because it relates the size of trout alevins to food availability, as predicted by the growth previously experienced by parents. ^NOTE     

生产函数异质性与地区农业经济增长——基于时空异质弹性生产函数模型

利用改革开放以来中国31个省(市、自治区,统计数据未含港、澳、台地区,下同)农业要素投入产出数据,基于农业要素收入份额存在较大差异的基本国情,从时间和空间维度放宽传统Cobb-Douglas生产函数模型产出弹性为固定常数的假定,通过构建时空异质弹性生产函数模型对改革开放以来中国不同地区、不同阶段农业要素投入、技术进步与...     

基于农作制分区的1985—2015年中国小麦生产时空变化

Comparing spatio-temporal variation characteristics of China’s wheat production, yield, sown area and yield-area-contribution in different farming zones in the past 30 years could help improving wheat planting layout and adjusting planting structure. Concentration index, rate of change, moving of gravity and resolution of yield-area-contribution were used to analyze spatio-temporal changes of China’s wheat production and yield-area-contribution based on county wheat production statistics including sown area, production and yield from 1985 to 2015. The wheat sown area decreased obviously in Northeast farming region, Northwest farming region and South farming region and increased rapidly in Huang-Huai-Hai farming region and Yangtze Plain farming region. In Huang-Huai-Hai farming region, the concentration indexes of Haihe Plain farming region, Huang-huai Plain farming region and Fenwei Basin farming region reached to 20.64%, 25.77%, and 21.65% respectively in 2015. Wheat production increased significantly by more than 48 milliontons in Huang-Huai-Hai farming region, and nearly 8 million tons Yangtze Plain farming region but decreased by more than 2.6 million tons in Northeast farming region. In Huang-Huai-Hai farming region, wheat production was concentrated in Haihe Plain farming region, Huang-huai Plain farming region and Yuxi Hill farming region. The average wheat yield continuously improved during the study period, Huang-Huai-Hai farming region and Northwest farming region had the yield increase up to 103.5 kg hm ^-2 and 92.9 kg hm ^-2 each year. Wheat yield in Yuxi Hill farming region, Fenwei Basin farming region and Haihe Plain farming region was relatively high in Huang-Huai-Hai farming region. The yield-reduced area was mainly caused by the decreasing of sown area, while the yield-area-contribution rate was different in yield-increased area. Yield-dominant counties were reduced, area-dominant counties were increased and yield-area-dominant counties were relatively steady. In production increased area, yield-dominant and yield-area-dominant counties were the main types in Huang-Huai-Hai Farming region, area-dominant and yield-area-dominant counties were the main types in Yangtze Plain farming region. Chinese wheat production was increasingly concentrated in Huang-Huai-Hai farming region which has high and rapid increase of wheat yield over the past three decades. Haihe Plain farming region, Huang-huai Plain farming region and Fenwei Basin farming region were the most concentrated areas in Huang-Huai-Hai farming region for wheat production during this period. Wheat yield and sown area jointly promoted the increase of wheat production in Huang-Huai-Hai farming region, wheat sown area was the crucial factor to increase wheat production in Yangtze Plain farming region, especially in the north of Jiangsu, Anhui province and greater part of Xinjiang.     

南极半岛周边水域南极磷虾渔场特征分析#br#

为了解南极半岛周边水域内南极磷虾(以下简称磷虾)拖网渔场的特征,基于2013年1月至2019年5月"福荣海"轮在南极半岛周边水域的生产数据,分析了水域内磷虾中心渔场年际空间分布和生产特征。结果表明,南极半岛周边水域内磷虾拖网渔场主要分布于布兰斯菲尔德海峡(Bransfield Strait)、乔治王岛(King George Island)和斯诺岛(Snow Island)3个区域;其中布兰斯菲尔德海峡内是历年磷虾生产最稳定的区域,尤以海峡中部靠近南极半岛一侧水域(58°~60°W、63°~64°S)的作业天数和年产量占比最高;乔治王岛和斯诺岛区域的作业天数和年产量占比较低,且主要分布在岛屿周边近岸水域;布兰斯菲尔德海峡内区域、乔治王岛区域和斯诺岛区域的历年产量占比分别为60.00%~99.97%、0.03%~21.15%和0.01%~17.25%,历年作业天数占比分别为61.76%~98.75%、1.25%~28.68%和0.84%~16.67%。布兰斯菲尔德海峡内渔场的生产主要在3—5月,日产量主要为150 t以下;乔治王岛区域生产主要在1月份,日产量以150 t以下为主;斯诺岛区域的日产量在3月份较高,主要以150~250 t为主。各年度的连续生产期分布区域以布兰斯菲尔德海峡中部水域为主;各日产量区间的生产日历年主要分布在布兰斯菲尔德海峡中部,各日单位小时产量生产日也呈现逐渐集中到布兰斯菲尔德海峡的趋势;各级别亚渔场历年主要分布区域均在布兰斯菲尔德海峡内。     

准噶尔盆地地表反照率时空变化特征及其影响因素分析

地表反照率变化影响地表辐射收支与能量平衡,从而对区域和全球气候产生影响.以准噶尔盆地为研究对象,利用MODIS卫星遥感数据产品MOD09A1反演地表短波反照率,结合气象数据和植被指数分析准噶尔盆地2001—2018年荒漠草地地表反照率时空变化特征及其影响因素.结果表明:准噶尔盆地地表反照率空间分布地域差异明显,地表反照...