Storage and density of soil organic carbon in urban topsoil of hilly cities: A case study of Chongqing Municipality of China   总被引：1，自引：1，他引：0  

LIU Yong  WANG Cheng  YUE Wenze  HU Yanyan 《中国地理科学(英文版)》2013,23(1):26-34

Rapid urbanization results in the conversion of natural soil to urban soil,and consequently,the storage and density of the soil carbon pools change.Taking Chongqing Municipality of China as a study case,this investigation attempts to better understand soil carbon pools in hilly cities.First,the vegetated areas in the study area were derived from QuickBird images.Then,topsoil data from 220 soil samples(0-20 cm) in the vegetated areas were collected and their soil organic carbon(SOC) densities were analyzed.Using the Kriging interpolation method,the spatial pattern of SOC was estimated.The results show that the SOC density exhibited high spatial variability in the urban topsoil of Chongqing.First,the SOC density in topsoil decreased according to slope in the order 2°-6° < 25°-90° < 0°-2° < 6°-15° < 15°-25°.Second,the newly developed areas during 2001-2010 had a lower SOC density than the areas built before 1988.Third,urban parks and gardens had a higher SOC density in topsoil,residential green land followed,and scattered street green land ranked last.For hilly cities,the variability of terrain affects the distribution of SOC.The Kriging results indicate that Kriging method combining slope with SOC density produced a high level of accuracy.The Kriging results show that the SOC density to the north of the Jialing River was higher than the south.The vegetated areas were estimated to amount to 73.5 km2 across the study area with an SOC storage of 0.192 Tg and an average density of 2.61 kg/m2.  相似文献   

Labile organic matter content and distribution as affected by six-year soil amendments to eroded Chinese mollisols   总被引：2，自引：0，他引：2  

Yueyu Sui  Xiaoguang Jiao  Wenting Chen  Xiaobing Liu  Xingyi Zhang  Guangwei Ding 《中国地理科学(英文版)》2013,23(6):692-699

Labile organic carbon （LOC） is a fraction of soil organic carbon （SOC） with rapid turnover time and is affected by soil fertilization. This investigation characterized the SOC content, LOC content and LOC distribution in the treatment plots of surface soil erosion at five levels （0-, 5-, 10-, 20- and 30-cm erosion）. The soil had received contrasting fertilizer treatments （i.e., chemical fertilizer or chemical fertilizer ＋ manure） for 6 years. This study demonstrated that both SOC and various LOC fractions contents were higher in the plots with fertilizer ＋ manure than in those with fertilizer alone under the same erosion conditions. The SOC and LOC contents de- creased as the erosion depth increased. Light fraction organic carbon, particulate organic carbon, easily oxidizable organic carbon （KMnO4-oxydizable organic carbon）, and microbial biomass carbon were 27% 57%, 37%-7%, 20%-25%, and 29%-33% higher respectively in the fertilizer ＋ manure plots, than in the fertilizer alone plots. Positive correlations （p 〈 0.05） between SOC content and different fractions contents were observed in all plots except the correlation between total SOC content and water-soluble organic carbon content in the different fertilization treatments. Obviously, fertilizer ＋ manure treatments would be conducive to the accumulation of LOC and SOC in the Black soil of Northeast China.  相似文献   

Species and plant community reorganization in the Trans-Mexican Volcanic Belt under climate change conditions     

Lourdes Villers-Ruiz  Diana Castañeda-Aguado 《山地科学学报》2013,10(6):923-931

This study analyzes six vegetation communities in relation to current climatic parameters and eight climate change scenarios along an elevation gradient extending from 2,710 m to 4,210m in the Trans-Mexican Volcanic Belt. The projected movements of 25 plant species with the current restricted or wide altitudinal distributions were also modeled. To relate climatic parameters to the species and communities, a Precipitation/Temperature(P/T)index was used both for the current and the different climate-change scenarios. The temperatures are expected to increase by 1.1°C to 1.7°C by 2020 and by2°C to 3°C by 2050. A decrease of 4% to 13% in the annual precipitation is expected for the 2020 horizon,and a reduction between 3% and 20% is expected for2050. The reductions in water availability were projected for all altitude levels and plant communities.The most marked reduction was under the HADLEYA2 scenario, in which the lower limit of the altitudinal range increased from 2,710 to 3,310 m(2050 horizon)with reductions in the P/T index between 36% and39% compared to the current climate. Most plant species tended to shift their distribution from 200 to300 m upward in the 2020 temporal horizon scenarios. The Pinus hartwegii, Alnus jorullensis and Pinus montezumae communities would have a shorter altitudinal range as they move upward and merge with the remaining species at the higher altitudinal range. For the 2050 temporal horizon,30% of the species, primarily those from the higher altitudinal range, would disappear because their P/Tindex values would be above the limit of plant survival(4,210 m).  相似文献   

A Comprehensive Method for Fractionating Soil Organic Matter Not Protected and Protected from Decomposition by Physical and Chemical Mechanisms     

César Plaza  José M. Fernández  Engil I. P. Pereira  Alfredo Polo 《洁净——土壤、空气、水》2012,40(2):134-139

The objective of this work was to describe a method for isolating meaningful and measurable soil organic matter (SOM) pools that differ in the mechanisms by which they are protected from decomposition. The proposed method is appropriate for soil C stabilization and sequestration studies. Unlike previous fractionation schemes, this procedure allows free SOM located between aggregates (unprotected C pool) and SOM occluded within both macroaggregates and microaggregates (C weakly and strongly protected by physical mechanisms, respectively) to be recovered separately, freed from the soil mineral matrix and the mineral‐associated SOM pool (C pool protected by chemical mechanisms) and thus well suited to advanced chemical characterization by ¹³C‐NMR. Briefly, free SOM is isolated by an initial density separation. Stable macroaggregates are broken up into stable microaggregates and intra‐macroaggregate SOM, which is then separated by density. Finally, intra‐microaggregate SOM is isolated from mineral‐associated SOM by a third density separation after ultrasonic disruption. The SOM dissolved during the fractionation procedure is also recovered. Results obtained on soil samples with contrasting textures suggested that clay content induces a decrease of the proportion of free organic C and an increase of mineral‐associated organic C content. Free SOM is characterized by a marked presence of undecayed organic material and biologically labile substances, such as carbohydrates and proteins. In contrast, SOM occluded within aggregates, especially within microaggregates, represents a more decomposed fraction, relatively enriched in unsubstituted‐aliphatic material, most probably lipid biopolymers.  相似文献   

雷州半岛红树林边缘效应及其对海岸有机碳库的影响   总被引：1，自引：0，他引：1  

杨娟  JAY Gao  刘宝林  ALAN Cheung  王铎  张苇 《海洋学报》2012,34(5):161-168

作为滨海湿地与邻近海区之间物质循环、能量和物种流动及其相互作用的重要界面,红树林的边缘效应对研究海陆生态系统相互作用,滨海湿地生物地貌形成过程以及海岸带有机碳库分布格局等方面的具有重要意义。文章以雷州半岛东岸红树林4种典型地貌分布区为重点,通过调查红树林前缘光滩,林缘及林内植被及土壤理化特征的变化,探讨红树林边缘效应的表现及其对土壤有机碳库的影响。结果表明,不同地貌类型红树林边界区的群落结构及土壤理化因子分布特征有所不同。边界区群落特征表现为林缘的冠层低于林内,叶面积指数低于林内,物种丰富度林内高于林缘(除河口区外),且林缘的植被盖度受风浪影响显著,表现出河口区>内湾区>岛屿区>前沿浪击区。土壤理化性质边缘效应表现为林缘的pH值、粒度低于光滩,氧化还原电位、盐度高于光滩(除内湾区外),而林内的土壤理化性质波动较大,可能受林缘植被演替及地貌双重影响。不同地貌单元红树林边界区的土壤表层有机碳含量,有机碳密度均表现为林内>林缘>光滩。综合影响表层土壤有机碳的主要生物及非生物因子进行主成分分析和相关分析,结果显示土壤表层有机碳密度与环境第一主成分呈显著负相关,即受植被盖度,叶面积指数和土壤pH因子影响密切。红树林土壤有机碳沉积虽然受到不同水文地貌的影响,但总体而言,红树林初级生产输入和土壤酸性环境对红树林林下土壤有机碳库的富存贡献显著。  相似文献   

北极孔斯峡湾表层沉积物中溶解有机质的来源与转化历史   总被引：7，自引：0，他引：7  

蔡明红  肖宜华  王峰  陆志波  黄清辉 《海洋学报》2012,34(6):102-113

在北极地区孔斯峡湾采集28个表层沉积物样品,测定了其中水溶性有机质(也称溶解有机质,DOM)的分子量分布、紫外/可见吸收光谱和三维荧光光谱特征,并利用平行因子分析(PARAFAC)模型对DOM的荧光组分和来源进行了解析。结果表明:孔斯峡湾表层沉积物中有色溶解有机质(CDOM)及其中的荧光溶解有机质(FDOM)含量均从内湾向外湾方向呈逐渐累积的趋势,但CDOM中的FDOM所占比例逐渐减小,与DOM趋于老龄化密切相关。沉积作用减弱以及长期的光化学降解和微生物降解作用对此起主要贡献,并导致腐殖质和小分子组分在沉积物DOM中所占的比例呈逐渐递增的趋势。沉积物DOM包含陆源类腐殖质、自生源类腐殖质和类蛋白等三个荧光组分,但是其组成比例空间差异很大。吸收光谱斜率比(S_R)随自生源所占百分比增加而减小,随DOM腐殖质组分中陆源与自生源的比值增加而增加;腐殖化指数(HIX)随类腐殖质与类蛋白质比值和水深的增加而增加,生物源指数(BIX)随自生源比例增加而增加。峡湾沉积物DOM的组成和来源存在着高度的空间差异,在冰川湾区由水体颗粒有机质(POM)的近期转化和迁移而来,而在峡湾中央及口门附近以较老的腐殖质为优势,主要源于水体DOM长期迁移和转化。研究表明,FDOM/CDOM,S_R,HIX和BIX等构成的CDOM光谱指纹信息可以作为揭露沉积物溶解有机质来源及迁移转化历史的工具,对探索海洋与冰川相互作用影响下的峡湾环境演变有着重要意义。  相似文献   

南黄海悬浮体浓度的平面分布特征及其输运规律   总被引：3，自引：1，他引：2  

韦钦胜  刘璐  臧家业  冉祥滨 《海洋学报》2012,34(2):73-83

重点分析和探讨了南黄海悬浮体浓度的平面分布及其水平输运,结果显示悬浮体浓度具有显著的空间区域化分布特征,其与该海域环流场的布局和季节转换存在良好的对应关系,南黄海环流是该海域悬浮体运移的主要动力和控制因素;江苏近岸海域在一年四季均为悬浮体浓度的最高值区,其悬浮体主要来源于潮流和海浪所引起的沉积物再悬浮以及苏北沿岸水的携带和输送,而且夏季悬浮体在该海域的累积还可为冬半年在黄海西部沿岸流作用下将其输运至东南海域提供很好的物源保证;长江口东北部海域在春、夏、秋三季出现东北向扩展的高值区,体现了长江冲淡水的影响;石岛外海在冬、春、秋三季也存在悬浮体浓度高值区,并具有向南黄海中部泥质区扩展的态势,这是鲁北沿岸流将现代黄河物质输运至此的结果。发现调查海域中部表底层在春秋季均存在云团状高值区,而且该海域悬浮体浓度自春季至秋季出现"双峰现象",这与春秋季水华期间浮游植物繁殖所产生的有机碎屑有关,并使作为悬浮体组成的海洋浮游生物有机质向沉积物转移,据此进一步指出这一物源可能对南黄海冷涡泥质区的形成、发育也具有一定的作用,该观点深化了对南黄海中部冷涡泥质区受上层生物活动影响以及泥质区物源的认识。  相似文献   

Food web structure within kelp holdfasts (Laminaria): a stable isotope study     

Gauthier Schaal  Pascal Riera  Cédric Leroux 《Marine Ecology》2012,33(3):370-376

Kelp holdfasts are highly reticulated structures which host a large diversity of small fauna. These microhabitats have been reported to play a crucial role in the biodiversity associated to kelp forest ecosystems. This study aimed at identifying trophic links and the main food sources sustaining food webs within communities associated with kelp holdfasts, through a stable isotope (δ¹³C and δ¹⁵N) approach. Sampling of the main invertebrates inhabiting Laminaria digitata holdfasts, and of their potential food sources, took place in February and May 2007. Stable isotope results reveal that most of the primary consumers, including filter-feeders and deposit-feeders, rely on the particulate organic matter sedimented within kelp holdfasts. Only three grazers departed from this general pattern. The correspondence between the stable isotope ratios of predators and sediment consumers indicated that this source is at the base of the main pathway through which energy and matter transit in the food web. δ¹⁵N ranges found for consumers revealed that the food web associated with kelp holdfasts is composed of 3.5 levels. In spite of the low diversity of food sources at the base of the food web, these microhabitats can therefore be considered micro-scale ecosystems, from a functional perspective.  相似文献   

Shifting accountabilities? Understanding the connections between national and provincial fisheries in Papua New Guinea     

Catherine S. Benson 《Marine Policy》2012,36(4):859-866

This paper examines the effects of fisheries decentralization strategies in Papua New Guinea. The paper assess the financial, human resources, information, and institutional mechanisms that the National Fisheries Authority uses to connect with provincial fisheries offices to show the consequences of institutional reforms. The findings suggest both intended and unintended effects, particularly in terms of shifting accountabilities and loyalty. These findings are broadly applicable to decentralization and institutional change scholars and practitioners interested in understanding how governments implement institutional change reforms and the effects of this implementation.  相似文献   

胶州湾大沽河口潮间带沉积物中叶绿素和有机质含量的季节变化   总被引：1，自引：0，他引：1  

尹盛乐  刘晓收  袁超  谭朋  胡金  刘阳  董树刚 《海洋湖沼通报》2012,(2):97-106

为了解胶州湾大沽河口潮间带沉积物中底栖微藻和有机质含量的季节变化,于2010年4月至2011年2月,分4次(春、夏、秋、冬)测定分析了沉积物中的叶绿素含量和有机质含量,并分析了沉积物的粒度组成及现场温度。结果表明,表层(0～2cm)沉积物叶绿素a含量为0.42～6.06mg/kg,有机质含量为0.48%～3.71%;次表层(2～5cm)叶绿素a含量为0.13～3.53mg/kg,有机碳质量为0.31%～3.78%;深层(5～8cm)叶绿素a含量为0.14～1.95mg/kg,有机质含量为0.47%～3.72%。经统计检验和Pearson相关性分析得出,胶州湾大沽河口沉积物中的叶绿素a含量春冬两季最高,夏季和秋季最低;叶绿素a含量与深度和温度呈负相关;与所处潮带、有机质含量、粉砂黏土含量在本实验中均无显著的相关性;有机质含量与季节关系不大,高潮带最高,其含量与粉砂黏土含量呈正相关,与叶绿素含量、深度和温度关系不明显。  相似文献