中国土壤有效含水量分布

1IntroductionAvailable soil water capacity (ASWC) is the volume of soil water that should be available to plants. It is commonly estimated as the amount of water held between field capacity (FC) and permanent wilting point (PWP) with corrections for salin…     

Tupu methods of spatial-temporal pattern on land use change: a case study in the Yellow River Delta

Comprehensive study on land-use change of spatial pattern and temporal process is the key component in LUCC study nowadays. Based on the theories and methods of Geo-information Tupu (Carto-methodology in Geo-information, CMGI), integration of spatial pattern and temporal processes of land-use change in the Yellow River Delta (YRD) are studied in the paper, which is supported by ERDAS and ARC/INFO software. The main contents include: (1) concept models of Tupu by spatial-temporal integration on land-use change, whose Tupu unit is synthesized by "Spatial·Attribute·Process" features and composed of relatively homogeneous geographical unit and temporal unit; (2) data sources and handling process, where four stages of spatial features in 1956, 1984, 1991, and 1996 are acquired; (3) integration of series of temporal-spatial Tupu, reconstruction series of "Arising" Tupu, spatial-temporal Process Tupu and the spatial temporal Pattern Tupu on land-use change by remap tables; (4) Pattern Tupu analysis on land-use change in YRD during 1956-1996; and (5) spatial difference of the Pattern Tupu analysis by dynamic Tupu units. The various landform units and seven sub-deltas generated by the Yellow River since 1855 are different. The Tupu analysis on land-use in the paper is a promising try on the comprehensive research of "spatial pattern of dynamic process" and "temporal process of spatial pattern" in LUCC research. The Tupu methodology would be a powerful and efficient tool on integrated studies of spatial pattern and temporal process in Geo-science.     

黄土丘陵沟壑区县域土壤有机质空间分布特征及预测

分析、预测土壤属性空间变异及其动态是区域土地质量评价和可持续土地利用的一个重要组成部分。在陕西省横山县采集了254个耕层(0~20cm)土样,利用数字地形与遥感影像分析技术,提取了相关地形与遥感指数,分析不同土地利用类型、不同地形条件下土壤有机质空间变异及分布特征,并利用相关因子进行回归预测分析。结果表明,县域土壤有机质平均含量很低,变异性较大。不同土地利用类型土壤有机质差异显著,其中以水稻田有机质含量最高,而林地和灌木林地相对较低。不同土地利用类型土壤有机质含量次序为:水稻田>川地>梯田>坝地>荒草地>坡耕地>林地>灌木林地。不同坡度分析表明,“0~3°”这一坡度等级有机质含量显著高于其它坡度等级;不同坡向有机质含量差异不显著,但不同坡向有机质含量存在一个明显的趋势,阴坡有机质含量整体上要比阳坡高。相关分析表明土壤有机质与高程h呈现负相关关系,与坡向的余弦值COSα正相关,与复合地形指数CTI正相关;土壤有机质和修正后的土壤调节植被指数(MSAVI)以及湿度指数(WI)正相关。利用相关环境变量及遥感指数进行多元线性逐步回归分析,预测结果不甚理想,存在一个平滑效应,对于残差解释相对较低,须进一步研究以更好的解释残差。     

半干旱黄土丘陵区退化人工林群落结构 调整下细根特征分析

根系尤其细根在植物的生长发育中起着重要作用,以甘肃省定西市巉口镇龙滩流域的白 杨及山杏 2 种典型退化人工林为研究对象,研究了人工林群落结构调整后形成的白杨+5 年生油 松、白杨+10 年生油松及山杏+云杉、山杏+樟子松混交林与单一纯林相比不同深度、不同径级下细 根的根长密度、根面积密度、根生物量密度、比根长及比根面积,以期揭示不同人工林恢复模式下 的细根分布特征。结果表明：（1）混交恢复模式起到了一定的积极作用,大部分混交林相较于纯林 细根的根长密度、根面积密度及根生物量密度在土壤表层均有所提高。混交林细根在浅层的占比 得到了提高,且随恢复年限的增加而升高。（2）细根根长密度、根面积密度及根生物量密度与土壤 全碳、全氮、含水量及有机碳之间以及比根长及比根面积与土壤全碳、土壤全氮及有机碳之间均存 在显著正相关关系。     

21世纪初中国土地利用变化的空间格局与驱动力分析

在全球环境变化研究中.以土地利用与土地覆盖动态为核心的人类一环境耦合系统研究逐渐成为土地变化科学(LCS)研究的新动向.基于覆盖中国21世纪初5年间隔的遥感卫星数据获取的1 km网格土地利用变化空间信息.依据近5年土地利用变化区域分异的显著特征,以及自然地理、经济发展与国家宏观政策因素综合考虑.设计针对21世纪初5年新的中国土地利用动态区划图,揭示土地利用变化的空间格局与驱动因素.总体上.21世纪初5年中国处于土地利用快速变化期,黄淮海平原、东南沿海地区与四川盆地城乡建设用地显著扩张,占用大规模优质农田,导致南方水田面积明显减少:西北绿洲农业发展与东北地区开垦导致北方旱地面积略有增加:受西部开发"生态退耕"政策的影响中西部地区林地面积显著增加,国家退耕还林还草政策成效明显,对区域土地覆盖状况的改善产生积极的影响:这一时段国土开发与区域发展战略的实施,包括"西部大开发"、"东北振兴"等国家重大政策,加之快速的经济发展是该阶段土地利用变化格局形成的主要驱动因素.     

基于等级钟理论的中国城市规模等级体系演化特征

首次引入国际著名城市地理学家M.Batty 提出的“城市规模等级钟”、“等级距离钟” 和“半生命周期” 理论; 利用地级以上城市的人口-等级数据, 测算了表征中国城市规模等 级演化特点的“等级钟”、“等级距离钟” 和“半生命周期”, 探讨了演化过程与机制; 利用 历史人口数据, 研究了若干历史城市近2000 年间的“等级钟” 演化特征。等级钟研究表明, 中国特大城市的规模等级钟变化较小, 城市位序稳定; 在区域空间差异上, 东部沿海城市等 级钟变化明显, 位序上升迅速; 东北地区城市等级钟呈现较大变化, 但演化方向与东部沿海 城市相反, 城市位序逐渐下降; 西部和内陆城市等级钟变化缓慢, 位序难以进入顶级序列之 中。等级距离钟表明, 中国高位序城市等级距离变化较小, 低位序和新设立城市的等级距离 变化明显, 整个城市系统的变化较为平缓, 仅在1980-1985 年间和2000-2005 年间出现较大变化, 体现了中国在改革开放初期与21 世纪开始的二次较为迅速的城市化发展历程。半生命周 期研究表明, 中国城市体系在生命周期现象不明显的总体背景下, 以20 世纪80 年代为时间 界标, 百位城市的前、后半生命周期仍然显现有较为明显的时间尺度差异, 自该时间界标以后, 新兴城市替代传统城市的速度开始加快。中国历史城市“等级钟” 表明, 城市位序等级 的变化是多种动因的叠加, 以政治职能为主的城市位序与其政治地位密切相关; 沿海、沿江 城市的位序则更多地与地理区位条件和经济政策相关联。     

Changes in daily extreme precipitation events in South China from 1961 to 2011

Based on the daily precipitation from a 0.5°×0.5° gridded dataset and meteorological stations during 1961-2011 released by National Meteorological Information Center, the reliability of this gridded precipitation dataset in South China was evaluated. Five precipitation indices recommended by the World Meteorological Organization (WMO) were selected to investigate the changes in precipitation extremes of South China. The results indicated that the bias between gridded data interpolated to given stations and the corresponding observed data is limited, and the proportion of the number of stations with bias between -10% and 0 is 50.64%. The correlation coefficients between gridded data and observed data are generally above 0.80 in most parts. The average of precipitation indices shows a significant spatial difference with drier northwest section and wetter southeast section. The trend magnitudes of the maximum 5-day precipitation (RX5day), very wet day precipitation (R95), very heavy precipitation days (R20mm) and simple daily intensity index (SDII) are 0.17 mm·a-1, 1.14 mm·a-1, 0.02 d·a-1 and 0.01 mm·d-1·a-1, respectively, while consecutive wet days (CWD) decrease by -0.05 d·a-1 during 1961-2011. There is spatial disparity in trend magnitudes of precipitation indices, and approximate 60.85%, 75.32% and 75.74% of the grid boxes show increasing trends for RX5day, SDII and R95, respectively. There are high correlations between precipitation indices and total precipitation, which is statistically significant at the 0.01 level.     

Assessment on environmental quality of heavy metals in agricultural soils of Chongming Island, Shanghai City

The environmental quality of heavy metals (Pb, Cd, Cr, As, Hg) in agricultural surface soil of Chongming Island was assessed by national, local and professional standards based on a large scale investigation, in which 28 samples from vegetable plots, 65 samples from paddy fields and 9 samples from watermelon fields were collected from whole island area. Results showed that the average concentration of Pb, Cd, Cr, As and Hg was 21.6 mg·kg-1 , 0.176 mg·kg-1, 69.4 mg·kg-1, 9.209 mg·kg-1 and 0.128 mg·kg-1, respectively. Compared with the background value of Shanghai City soil, except for Pb and Cr, all the other heavy metals average concentrations in Chongming Island agricultural surface soil exceeded their corresponding natural-background values. The concentrations of Cd, As and Hg were 33.0%, 1.2% and 26.3% higher than the background value of Shanghai City, respectively. In addition, inverse distance interpolation (IDW) tool of GIS was also applied to study the spatial variation of heavy metals. The results indicated that most of agricultural soil quality was good, and the ratio of ecological, good soil, certified soil and disqualified soil were 1.26%, 97.1%, 1.47% and 0.12%, respectively. About 10.1%, 85.7%, 27.0%, 55.4% and 55.2% soil samples exceeded the Pb, Cd, Cr, As and Hg background value of Shanghai City, respectively. Among these three land use type soils, vegetable soil was most seriously polluted by heavy metals, which is probably related to the over-application of pesticides. The annual deposition fluxes of Pb, Cd, As and Hg were 7736 μg·m-2·a-1, 208 μg·m-2·a-1, 2238 μg·m-2·a-1 and 52.8 μg·m-2·a-1, respectively. Crop straw burning was the important source of heavy metals of atmospheric deposition, and atmospheric deposition contributed a lot to heavy metals in agricultural soil in Chongming Island.     

Spatiotemporal characteristics,patterns, and caus-es of land-use changes in China since the late 1980s

Land-use/land-cover changes (LUCCs) have links to both human and nature interactions. China's Land-Use/cover Datasets (CLUDs) were updated regularly at 5-year intervals from the late 1980s to 2010,with standard procedures based on Landsat TM\ETM+ images. A land-use dynamic regionalization method was proposed to analyze major land-use conversions. The spatiotemporal characteristics,differences,and causes of land-use changes at a national scale were then examined. The main findings are summarized as follows. Land-use changes (LUCs) across China indicated a significant variation in spatial and temporal characteristics in the last 20 years (1990-2010). The area of cropland change decreased in the south and increased in the north,but the total area remained almost unchanged. The reclaimed cropland was shifted from the northeast to the northwest. The built-up lands expanded rapidly,were mainly distributed in the east,and gradually spread out to central and western China. Woodland decreased first,and then increased,but desert area was the opposite. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included (1) an accelerated expansion of built-up land in the Huang-Huai-Hai region,the southeastern coastal areas,the midstream area of the Yangtze River,and the Sichuan Basin;(2) shifted land reclamation in the north from northeast China and eastern Inner Mongolia to the oasis agricultural areas in northwest China;(3) continuous transformation from rain-fed farmlands in northeast China to paddy fields;and (4) effectiveness of the "Grain for Green" project in the southern agricultural-pastoral ecotones of Inner Mongolia,the Loess Plateau,and southwestern mountainous areas. In the last two decades,although climate change in the north affected the change in cropland,policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century,the anthropogenic factors that drove variations in land-use patterns have shifted the emphasis from one-way land development to both development and conservation.The "dynamic regionalization method" was used to analyze changes in the spatial patterns of zoning boundaries,the internal characteristics of zones,and the growth and decrease of units. The results revealed "the pattern of the change process," namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning,variations in unit boundaries,and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the "pattern" and "process" of land use and the causes for changes in different types and different regions of land use were explored.     

极端降雨事件对不同类型生物土壤结皮覆盖土壤碳释放的影响

于2011年5-8月,选择腾格里沙漠东南缘人工固沙植被区藻类、藓类和混生结皮覆盖的土壤为对象,研究了极端降雨量(降雨量44.7 mm、强度0.04 mm,min-1)、极端降雨强度(降雨量8.3 mm、强度0.55 mm·min-1)及普通降雨(降雨量16.3 mm、强度0.02 mm·min-1)条件下的碳释放过程.碳释放量的测定采用Li-6400-09土壤呼吸室,降雨结束后立即开始观测,直到呼吸速率恢复到降雨前水平时停止观测.结果表明:极端降雨(降雨量和降雨强度)结束初期藻类和混生结皮覆盖土壤的呼吸速率受到明显抑制,藻类结皮覆盖土壤呼吸速率分别为0.12 μmol·m-2·s-1和0.41 μmol·m-2·s-1,混生结皮覆盖土壤呼吸速率分别为0.10 μmol·m-2·s-1和0.45μmol·m-2·s-1;而极端降雨对藓类结皮覆盖土壤的影响不明显,呼吸速率分别为0.83 μmol·m-2·s-1和1.69μmol·m-2·s-1.这说明处于演替高级阶段的藓类结皮能够很好地应对短期的极端降雨事件.     

基于DMSP/OLS夜间灯光数据的1995-2009年中国地级市能源消费动态

能源是国民经济发展的重要支撑,便捷准确地获取能源消费时空动态信息,对于合理制定能源政策具有重要意义。基于DMSP/OLS 夜间灯光数据和能源统计数据之间的定量关联,在地级市尺度上模拟了中国1995-2009 年能源消费的空间格局,并采用空间自相关分析探讨其时空动态特征。研究表明：基于DMSP/OLS夜间灯光数据模拟中国各地市能源消费具有一定的可行性,该数据能够比较可靠地反映能源消费的时空动态;1995-2009 年中国大多数地市的能源消费量较低,中低强度能源消费区土地面积占全国72.66%,高能源消费强度区集中分布在中国东部地区;中国能源消费量存在显著的空间集聚性（历年Moran’s I 指数都大于0.4）,全国地级市能源消费“高-高”聚集和“低-低”聚集现象明显。     

中亚热带山区土地利用变化对土壤有机碳储量和质量的影响

通过对中亚热带山区天然林、人工林(用材林和经济林)、次生林、果园和坡耕地等7 种典型土地利用方式的土壤有机碳储量及质量的研究, 结果表明: 中亚热带山区天然林转变 为其他土地利用类型后, 土壤有机碳储量下降了25.6%~51.2%, 而表层0~20 cm 土壤有机碳 储量下降了45.1%~74.8%, 比底层土壤有机碳对土地利用变化的响应更为敏感。土壤轻组有机碳储量(0~60 cm) 下降了52.2%~84.2%, 轻组有机碳占总有机碳比例从13.3%降到3.0% ~10.7%, 比土壤总有机碳对土地利用变化更为敏感。天然林转变为其他土地利用类型后土壤 有机碳损失巨大的原因主要与凋落物归还数量及质量, 水土流失和经营措施对土壤(特别是表层土壤) 的扰动引起土壤有机质加速分解等因素有关。坡耕地人为干扰最严重, 土壤有机 碳下降幅度最大。中亚热带山区土地利用变化引起土壤有机碳储量下降幅度高于全球平均水平, 主要与区域降水和地貌条件有关。因此, 保护山区脆弱生态环境, 加强天然林保护和植 被恢复, 合理营造人工林, 减少耕作, 对山区土壤碳吸存、减缓大气CO₂ 浓度升高和气候变化以及促进山区可持续开发的生态服务功能发展都具有重要意义。     

Spatial variability of soil moisture content and its relation to environmental indices in a semi-arid gully catchment of the Loess Plateau, China

The degree of spatial variability of soil moisture and the ability of environmental attributes to predict that variability were studied at the Da Nangou catchment (3·5 km²) in the semi-arid loess area of China. Soil moisture measurements were performed biweekly at five depths in the soil profile (0–5 cm, 10–15 cm, 20–25 cm, 40–45 cm and 70–75 cm) from May to October 1998 and from May to September 1999 using Delta-T theta probe. Results indicated that with increasing soil depth, the mean soil moisture content increases significantly for five layers and the coefficients of variation (CV) also increases with depth from 10–15 cm. It was observed that heavier rains and higher mean moisture contents are often associated with lower spatial variability (CV). Environmental attributes such as land use and topography play controlling roles in the spatial distribution of soil moisture content. However, the relative roles of these environmental indices vary with soil depth. The dominant controls on spatial variability of the time-averaged soil moisture changes from land use, aspect, relative elevation and hillslope position in the surface soil (0–5 cm) to relative elevation, hillslope position and aspect in the subsurface soil (10–15 cm, 20–25 cm), and to land use, relative elevation and slope gradient at larger depths (40–45 cm, 70–75 cm). The dynamic behavior of influences of different environmental indices on the layer-averaged soil moisture depends on several factors. In general, the correlation of soil moisture with slope gradient shows a more significant increase following a greater amount of antecedent precipitation (except for the extremely heavy storms), and declines afterwards. The relation of soil moisture with relative elevation and hillslope position exhibits an opposite trend. It was observed that the influence of land use corresponds to the difference in vegetative characteristics, with a stronger influence in June and August with a greater difference in vegetation. A significant influence of cos(aspect) was found during early spring and autumn with a rapid transient in solar irradiation. Finally, it was found that the sample size is adequate to estimate the catchment mean soil moisture at all five depths and on all 10 observations in 1999 (81 sites), while it is only enough for the upper soil layers (0–5 cm and 10–15 cm) in 1998 (26 sites).     

Effects of soil degradation on infiltration rates in grazed semiarid rangelands of northeastern Patagonia, Argentina

In grazed semiarid ecosystems, considerable spatial variability in soil infiltration exists as a result of vegetation and soil patchiness. Despite widespread recognition that important interactions and feedbacks occur between vegetation, runoff and erosion, currently there is only limited quantitative information on the control mechanisms that lead to differences in infiltration from different vegetation types. In this paper, we determine (i) the relationship between vegetation and soil surface characteristics and (ii) the soil infiltration rate by using rainfall simulations on runoff plots (0.60 × 1.67 m) in three plant communities of northeastern Patagonia: grass (GS), degraded grass with scattered shrubs (DGS), and degraded shrub steppes (DSS). Our results clearly indicate that vegetation and soil infiltration are closely coupled. Total infiltration was significantly higher in the GS (69.6 mm) compared with the DGS and DSS (42.9 and 28.5 mm, respectively). In the GS, soil infiltration rate declined more slowly than the others communities, reaching a terminal infiltration rate significantly greater (57.7 mm) than those of DGS and DSS (25.7 and 12.9 mm, respectively). The high rate of water losses via overland-flow may limit the possibilities for grass seedling emergence and establishment and favor the persistent dominance of shrubs.     

基于综合指标法的中国生态系统服务保护有效性评价研究

将生态系统服务保护纳入到传统的以保护区为基础的自然保护之中是生态保护研究的新领域。利用综合指标方法,分析了中国从2000-2010年的4种生态系统服务时空变化特征;并对中国的七大生态保护和恢复区域的服务空间保护成效进行评价,提出了国家尺度上的生态系统服务保护优先性分级。主要结论为：① 中国的生态系统服务自西北向东南逐渐增加,显著增加区主要分布在黄土高原地区,显著减少区主要分布在东北及华北地区。黄土高原的生态系统服务提高主要是农田向草地和林地、草地向林地的转换引的;华北地区的降低主要是耕地的减少以及人工用地的增加引起的;东北地区是由于林地向耕地草地、耕地向湿地与人工用地的转换引起的。② 七大生态保护和恢复区的生态系统服务均为增加趋势而且显著增加面积大于减少面积;显著增加面积最大的为三北防护林工程区、最小的为重点生态功能区;显著减少最大为重要生态功能区、最小的为三北防护林工程区。而且,对服务的保护成效在重要生态功能区最高,其次为天然林保护工程区,其余区域均小于全国平均水平。③ 提出的生态系统服务保护优先性等级中,极高级别占到了国土面积的26.18%,保护的生态系统服务量占到全国总量的64.19%,保护成效为全国平均水平的2.47倍。     

横断山区土壤地球化学及元素含量

概述了横断山区主要土类的地理分布情况，土壤理化性质及地球化学特征，然后分析土壤中 Ｃｕ，Ｚｎ，Ｐｂ，Ｎｉ，Ｃｏ，Ｃｄ和 Ｆ７种元素含量及其分布特征     

干旱半干旱地区草原灌丛荒漠化及其生物地球化学循环

干旱和半干旱地区草地生态系统木本植物入侵及其导致的草原灌丛化已经成为全球范 围普遍发生的现象, 是草地沙化和荒漠化的一个重要标志。干旱生态系统中, 此种类型的植被变 化将对区域和全球生物地球化学循环产生显著影响。过度放牧、区域气候干旱化和自然火过程是 导致灌丛入侵和发展的主要控制因子。草原灌丛化过程中, 草地生态系统分布较为均匀的土壤养 分及相关元素在水平和垂直方向发生分异, 关键生命元素C、N、P 、S 生物地球化学循环的变化 将对全球气候变化产生显著作用。全球气候变化与草原灌丛荒漠化之间存在潜在的反馈机制, 人 类扰动的影响将使这种反馈作用变得更加迅速和灵敏。     

Estimation of soil organic carbon reservoir in China

The paper respectively adopted physio-chemical properties of every soil stratum from 2473 soil profiles of the second national soil survey. The corresponding carbon content of soils is estimated by utilizing conversion coefficient 0.58. In the second soil survey, the total amount of soil organic carbon is about 924.18×108t and carbon density is about 10.53 kgC/m2 in China according to the area of 877.63×106 hm2 surveyed throughout the country. The spatial distribution characteristics of soil organic carbon in China is that the carbon storage increases when latitude increases in eastern China and the carbon storage decreases when longitude reduces in northern China. A transitional zone with great variation in carbon storage exists. Moreover, there is an increasing tendency of carbon density with decrease of latitude in western China. Soil circle is of great significance to global change, but with substantial difference in soil spatial distribution throughout the country. Because the structure of soil is inhomogeneous, it could bring some mistakes in estimating soil carbon reservoirs. It is necessary to farther resolve soil respiration and organic matter conversion and other questions by developing uniform and normal methods of measurement and sampling.     

The variation of sediments organic carbon content in Chongming east tidal flat during Scirpus mariqueter growing stage

The investigations on the organic carbon (OC) of core sediments were carried out in Chongming east tidal flat (CM) during Scirpus mariqueter growing stage (from April to December 2004) in Yangtze Estuary. The Yangtze River annually transports a runoff discharge of 30,000 m3/s, carrying about 480 million tons of sediments to the estuarine and coastal area, which formed a great OC pool. In the sampling spots, seven quadrats of 50 cm × 50 cm and five sediments cores of 20 cm deep (40 cm deep in December) were randomly established in order to collect vegetations and core sediments samples during the low tide each month except November. After pretreatment, the core sediments were sieved and their OC contents were measured according to the potassium dichromate method. The results show that the higher surface sediment OC content in summer comes from allochthonous terrigenous particle settlements on the Chongming east middle tidal flat S. mariqueter zone. In autumn and winter, the decomposing of the defoliated S. mariqueter increases the surface sediments OC content. Settling velocity, sediment temperature and S. mariqueter growth are the main factors that can control the sediment carbon content. Summer is the "carbon losing" period of the tidal flat sediments, while from September, it changes into the "carbon accumulating" period of sediment OC pool because of the decomposing of dead S. mariqueter community in the sediments. From this alternation of "carbon losing" period and "carbon accumulating" period, we conclude that carbon in the OC pool of the middle tidal flat S. mariqueter zone sediments mainly comes from the atmospheric carbon rooted by S. mariqueter photosynthesis.