保安湖—湖湾大型水生植物群落格局的研究

用地质统计学中的半方差和双对数半方差图对保安湖-湖湾(黄风口)的大型水生植物群落格局进行了研究,在不同的尺度上对群落及其主要组成种类的空间异质性进行了定量的描述。结果表明：保安湖黄风口大型水生植物群落的双对数半方差图存在线性区域,群落具有分形特征(自相似性).在不同的尺度下,群落和各组成种类空间格局具有不同的分形维数值,异质性程度存在差异。但其异质性程度不高,建议进行群落调查时,样方尺度应取520m;单一种群调查时的样方尺度取380m.     

保安湖大型水生植物在碳循环中的作用

通过全年的生物量调查的方法,对保安湖的优势种水草生产量进行调查;并进行两个月的优势种水草的分解实验,同时结合各优势水草的含碳量和保安湖的湖水溶解有机碳(DOC)和颗粒有机碳(POC)的动态,阐明大型水生植物在保安湖生态系统碳循环中的作用。同时在整个湖泊范围内,运用分形几何学对水草中的含碳量格局进行分析。     

白音华矿区土壤重金属含量的空间异质性

为探讨开矿对白音华矿区土壤重金属空间分布的影响,本研究以内蒙古西乌珠穆沁旗白音华煤矿区周边土壤为对象,分析了距离矿区8 km内的重金属Cu、Cr、Pb和Mn含量的空间异质性.结果表明:土壤重金属Cu、Cr、Pb和Mn的平均含量分别为12.7、32.6、29.9和201.3 mg ? kg-1,其变异系数分别为26.8％...     

可溶性有机碳在土壤剖面淋溶过程中的分馏

选取中亚热带两种不同类型土壤为研究对象,采集0～10、10～20、20 ～ 40、40～60、60～80、80～ 100 cm土层土壤样品,提取米槠新近凋落物的可溶性有机碳(DOC)溶液为初始DOC,研究其在土样中淋溶时的分馏现象和截留特征.结果表明:初始DOC在土柱中淋溶时,其浓度随深度增加呈逐层下降的趋势,而且化学结构更为简单,被土壤截留的DOC中主要是疏水性组分,但随着土层深度增加,亲水性DOC的截留量呈上升趋势;红外光谱显示含有芳环的疏水性物质最易被吸附,而烷烃和简单的碳水化合物则最有可能随土壤溶液进入下层土壤;由于到达下层土壤的DOC中易被吸附组分含量的减少,限制了其吸附能力的发挥,因此主要的吸附过程发生在40 cm以上土层,表明DOC本身的化学性质比土壤性质更能影响其吸附行为;不同类型土壤的截留量具有显著差异,这与土壤黏粒和铁铝氧化物的含量呈显著正相关.     

喀斯特峰丛洼地小流域表层土壤微量元素的空间异质性

基于网格取样(80 m×80 m),利用经典统计学和地统计方法分析了典型喀斯特峰丛洼地小流域163个表层(0～20 cm)土壤样点微量元素(Pb、Cr、Ni、Cu、Zn、B)的空间变异特征.结果表明:研究区土壤6种微量元素含量的差异及变异系数均较大,平均含量大小顺序为Zn＞Cr＞Ni＞Pb＞B＞Cu,平均变异程度依次为Ni＞Cu＞Zn＞Pb＞B＞Cr.不同微量元素具有不同的空间结构和最佳拟合模型,除Cr呈中等程度自相关、变程较长、空间连续性较好外,其他5种元素均呈强烈自相关,变程较短,空间依赖性较强.6种微量元素的Kriging等值线图较为相似,表明研究区土壤微量元素含量有着相似的分布趋势,表现为东部高,南北两头低,洼地高,坡地低.人为干扰和自然条件(植被、裸岩率、坡度、坡向)是土壤微量元素空间异质性的主要影响因素.     

长白落叶松人工林天然更新幼苗分布格局及其研究方法的比较

长白落叶松是东北东部地区主要造林树种之一．该文研究了55a生长白落叶松人工林天然更新幼苗的空间分布格局．测定了样地内（30m×18m）所有天然更新幼苗的坐标、地径和苗高．在幼苗坐标点图的基础上,进行了23个取样尺度（离散尺度）下的相邻格子法的空间格局分析：采用Poisson分布、负二项分布和正二项分布拟合幼苗的离散分布,方差均值比、Morisita指数和最近邻体法确定了空间分布格局,C-指数、Green指数和负二项参数K值度量了它们的聚集强度．利用更新幼苗的坐标点图,采用地统计学中自々半方差分析方法和空间点格局方法（采用Ripley二次分析法）研究了尺度连续变化条件下更新幼苗空间分布格局和聚集强度的变化并确定了其聚集规模,利用最近邻体法的计算方法分析了更新幼苗的自然定植特点．结果表明：1）更新幼苗所有离散尺度下（样方面积从1m^2到18m^2）均呈聚集分布．连续尺度下,在0—10．5m的半径区间内呈聚集分布,在10．5—12．3m的半径区间内呈随机分布．2）离散尺度下（样方面积从1m^2到18m^2）,聚集强度随尺度的增加而增加．连续尺度下,在0．10．5m的半径区间内,聚集强度随尺度的增加表现出先增加后降低的趋势,在半径（尺度）为4．2m处聚集强度最大．3）此次调查的样地范围内天然更新幼苗呈现聚集状态生长的平均最大聚集斑块（聚集规模）的半径为4．79m．4）天然更新幼苗之间的平均距离为0．30-0．42m,更新幼苗生长在与母树相距2．99—3．26m之外的空间．5）相邻格子法（传统的样方方法）和空间点格局分析法对格局的判别和格局强度的确定基本一致,但是空间点格局分析法能够反映出尺度连续变化条件下格局和格局强度的变化．它与最近邻体法和地统计学方法等以种群分布的坐标点图为数据源的     

宿主-寄生物相互作用种群模型中的混沌与分形现象

自然界具有离散世代的宿主-寄生物相互作用的种群模型都以差分方程组来描述,由于宿主-寄生物相互关系具有不同的类型,模型的功能反应函数也具有多种形式.通过数值模拟试验,分析研究了聚集效应模型随参数变化时表现出的混沌动态行为以及吸引域的自相似分形属性.结果显示虽然在一定参数范围内种群数量显示严格的周期,但混沌动态是不可避免的,共存的多吸引子初值区域显示出自相似分形属性.说明混沌动态行为和分形属性是离散的种群互作用种群模型中必然出现的现象.     

大型无脊椎动物群落指数和群落数量指数在河流水质评价中的应用

本文介绍了新西兰常用的大型无脊椎动物群落指数(MCI)和大型无脊椎动物群落数量指数(QMCI)的原理及使用方法,并利用MCI和QMCI对新西兰惠灵顿地区40条河流53个监测点进行评价.结果表明:MCI和QMCI均与河流营养指标呈极显著相关关系,可用来监测和评价水体的营养污染状况;二者快速准确地监测出惠灵顿地区河流水质总体良好,但部分河流污染严重,并分析了污染的原因.MCI与QMCI存在极显著相关关系,但MCI与营养指标间的相关关系大于QMCI,可以准确地反映出水体中营养元素的富集状况.     

地统计学分析方法在水生态系统研究中的应用

简要介绍了地统计学分析方法的发展和在生态学中的应用情况,提出了将这种方法应用于水生态系统空间格局分析的可能性,然后用梅子垭水库水体藻类叶绿素a含量为例对其浓度场的水平2维空间格局进行了分析,并以此确定了叶绿素a在整个空间和不同方位上空间格局的变化情况。     

生态学中的点格局研究概况及其在国内的应用

点格局分析是研究生态学格局的工具之一,近年来在生态学中的应用越来越多。为深入了解点格局分析方法在国内的研究与应用情况,以所总结的研究进展、一般步骤和基本要点为背景,分析评述了1996—2015年期间以点格局为主题的国内中文核心期刊文献。结果表明,在国内生态学格局研究中,应用研究占据主导地位,研究对象广泛,包括以树木为主的乔、灌、草等不同生活型的植物,甚至包括景观;基础研究,包括概括性统计量、零模型与点过程模型等方面,以及专用软件工具包的开发等研究薄弱。在应用中存在一定问题,主要表现为:概括性统计量使用单一,且以Ripley的K-函数及其变形为主;零模型(或点过程模型)是科学问题的统计表达,但是有一半以上的研究未明确给出零模型。建议在未来应用研究中重视多种统计量的组合使用和原假设的建立,在探讨热带、亚热带森林等具有复杂空间结构系统的多样性格局时,考虑对象的不同世代和系统的不同垂直层次,并加强多变量或三维概括性统计量的开发、点格局分析方法与动态过程模型的结合研究等工作。     

Changes in dissolved lignin-derived phenols, neutral sugars, uronic acids, and amino sugars with depth in forested Haplic Arenosols and Rendzic Leptosols

A major part of the dissolved organic matter produced in the organic layers of forest ecosystems and leached into the mineral soil is retained by the upper subsoil horizons. The retention is selective and thus dissolved organic matter in the subsoils has different composition than dissolved organic matter leached from the forest floor. Here we report on changes in the composition of dissolved organic matter with soil depth based on C-to-N ratios, XAD-8 fractionation, wet-chemical analyses (lignin-derived CuO oxidation products, hydrolysable sugars and amino sugars) and liquid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Dissolved organic matter was sampled directly beneath the forest floor using tension-free lysimeters and at 90cm depth by suction cups in Haplic Arenosols under Scots pine (Pinus sylvestris L.) and Rendzic Leptosols under European beech (Fagus sylvatica L.) forest. At both sites, the concentrations of dissolved organic carbon (DOC) decreased but not as strongly as reported for deeply weathered soils. The decrease in DOC was accompanied by strong changes in the composition of dissolved organic matter. The proportion of the XAD-8-adsorbable (hydrophobic) fraction, carboxyl and aromatic C, and the concentrations of lignin-derived phenols decreased whereas the concentrations of sugars, amino sugars, and nitrogen remained either constant or increased. A general feature of the compositional changes within the tested compound classes was that the ratios of neutral to acidic compounds increased with depth. These results indicate that during the transport of dissolved organic matter through the soils, oxidatively degraded lignin-derived compounds were preferentially retained while potentially labile material high in nitrogen and carbohydrates tended to remain dissolved. Despite the studied soils' small capacity to sorb organic matter, the preferential retention of potentially refractory and acidic compounds suggests sorption by the mineral soil matrix rather than biodegradation to govern the retention of dissolved organic matter even in soils with a low sorption capacity.     

Effect of Dissolved Organic Matter from Wheat Straw or Swine Manure on the Cu Adsorption in Three Chinese Soils

Batch equilibration experiments were conducted to evaluate the effects of dissolved organic matter (DOM) from wheat straw (DOMw) and swine manure (DOMs) on copper (Cu) adsorption and behavior in Haplic Phaeozems, Haplic Acrisol, and Eutric Fluvisol in China. Results showed that the Cu adsorption isotherms were well fitted with both Langmuir and Freundlich equations. The Cu maximum potential adsorption capacity of the three soils followed the order of Eutric Fluvisol > Haplic Phaeozems > Haplic Acrisol. DOMw and DOMs increased the Cu adsorption capacity in Haplic Phaeozems and Haplic Acrisol, and the promoting role of DOMs on Cu adsorption was obviously higher than that of DOMw. Increasing DOM concentration of DOMw and DOMs promoted the Cu adsorption in Haplic Phaeozems and Haplic Acrisol. However, this promoting effect weakened with increasing DOM concentration. Moreover, DOMw and DOMs inhibited the Cu adsorption in Eutric Fluvisol, and this inhibitory effect significantly increased with increasing DOM concentration. The results may be used to assess the potential environmental contamination of the studied soils and to control the application of organic fertilizers.     

森林凋落物淋溶中的溶解有机物与紫外-可见光谱特征

对格氏栲(Castanopsis kawakamii)和杉木(Cunninghamia lanceolat)人工林新近凋落物、半分解层(F层)和分解层(H层)凋落物进行室内模拟淋洗实验,研究了凋落物淋溶过程中溶解有机碳(DOC)浓度变化及紫外-可见(UV-Vis.)光谱特征.结果表明,格氏栲和杉木人工林新近凋落物淋出液的DOC浓度较低,F层淋出液的DOC浓度较高;格氏栲凋落物淋出液的DOC浓度基本上随淋溶次数的增加而降低,杉木的则先升后降.淋出液中溶解有机物(DOM)的紫外吸收值均随波长的增加而减小,且UV-Vis.吸收曲线均在200nm附近出现吸收峰,不同来源DOM的E240/E420存在显著差异;同一样品各次淋出液的DOC浓度与E200有很好的线性关系(P2＞0.90),据此,可用E200值估算DOC浓度.     

Characterization and origin of polar dissolved organic matter from the Great Salt Lake

Polar dissolved organic matter (DOM) was isolated from a surface-water sample from the Great Salt Lake by separating it from colloidal organic matter by membrane dialysis, from less-polar DOM fractions by resin sorbents, and from inorganic salts by a combination of sodium cation exchange followed by precipitation of sodium salts by acetic acid during evaporative concentration. Polar DOM was the most abundant DOM fraction, accounting for 56% of the isolated DOM. Colloidal organic matter was ¹⁴C-age dated to be about 100% modern carbon and all of the DOM fractions were ¹⁴C-age dated to be between 94 and 95% modern carbon. Average structural models of each DOM fraction were derived that incorporated quantitative elemental and infrared, ¹³C-NMR, and electrospray/mass spectrometric data. The polar DOM model consisted of open-chain N-acetyl hydroxy carboxylic acids likely derived from N-acetyl heteropolysaccharides that constituted the colloidal organic matter. The less polar DOM fraction models consisted of aliphatic alicyclic ring structures substituted with carboxyl, hydroxyl, ether, ester, and methyl groups. These ring structures had characteristics similar to terpenoid precursors. All DOM fractions in the Great Salt Lake are derived from algae and bacteria that dominate DOM inputs in this lake.     

Bacterial Degradation of Dissolved Organic Matter from Two Northern Michigan Streams

This study used high-pressure size exclusion chromatography (HPSEC) to measure the changes in molecular weight distributions of dissolved organic matter (DOM) of two Northern Michigan streams following inoculation with bacterial concentrates from the same locations. During the initial 12 h of the experiment, weight average molecular weight (M _w ) of DOM decreased, as high molecular weight components were lost from solution. After 12 h, the M _w of DOM increased, primarily because of a loss of intermediate to lower molecular weight components. Leucine incorporation showed little or no bacterial metabolism during the first 12 h, but metabolism increased substantially after 12 h. The initial loss of high molecular weight components during the period of little or no bacterial metabolism suggests preferential adsorption of these components to the bacterial surfaces, perhaps followed by metabolism. This suggested interpretation is consistent with previous observations of preferential adsorption of higher molecular weight components to viable but non-metabolizing Bacillus subtilis and to mineral surfaces. The latter loss of lower molecular weight components was most likely due to bacterial metabolism of the DOM, which is consistent with previous observations that lower molecular weight components are more biodegradable. The HPSEC technique uses 254 nm wavelength for detection and focuses primarily on humic- and fulvic-type components rather than low molecular weight organic molecules, such as carbohydrates. Thus, results confirmed that humic/fulvic components are biodegradable, but did not address other DOM components.     

Phosphorus fractions in montane forest soils of the Cordillera de Piuchué, Chile: biogeochemical implications

The Hedley fractionation procedure as modified by Tiessen and Moir (1993) was used to evaluate the amounts of P in several soil chemical pools in an old, unglaciated landscape at 600 m elevation in the Cordillera de Piuchué, Chile (42° 30′ S. 74° W). This is an area of primary forests which have escaped disturbance from forest harvesting, land clearing and the deposition of anthropogenic chemicals. Two study watersheds are conifer-dominated with moorland on wind-exposed ridgetops. In a third study watershed, vegetation is dominated by evergreen broadleaf trees. Soils are thin (ca. 40 cm) and have a high organic matter content. Across all communities, most of the soil P is in non-labile forms in organic combinations or in combination with secondary soil minerals. Little P was present in primary minerals. The remainder (ca. 20%) was in labile forms extractable with anion exchange resin or bicarbonate solution. From litterfall and allometric relationships, we estimated the annual P requirement of growing vegetation to be <1 kg ha^-1 in the moorland and < 3 kg ha^-1 in the conifer and mixed forests. This is substantially less than the standing pool of resin-extractable P (ca. 20 kg ha^-1), which is considered to be P fraction most readily available to plants. Resin-extractable P was strongly correlated with soil carbon content ( R² =0.72 − 0.87, p < 0.001) suggesting that soil organic matter is the likely proximate source of plant-available P. On a kg ha^-1 basis, the most labile forms of P did not differ significantly across 3 of the 4 community types despite dramatic differences in species, live biomass and annual P requirement, suggesting little control of available P pools by forest vegetation type. On a more detailed level, resin-extractable P was strongly correlated with HCO₃-extractable organic (and inorganic) P. This is consistent with other findings of P behavior in acid soils high in organic matter in which microbial transformations are key in regulating pools of plant-available P. This revised version was published online in June 2006 with corrections to the Cover Date.