桂北喀斯特峰丛洼地植物群落特征及其与土壤的耦合关系

基于喀斯特峰丛洼地草丛、灌丛、次生林、原生林4个生态系统24个样地(20 m × 20 m)的系统取样调查, 研究了喀斯特峰丛洼地不同生态系统群落的结构组成与生物多样性特征, 选取代表植物群落和土壤性质的35个指标, 对不同生态系统及整个喀斯特脆弱生态系统植物群落与土壤主要养分、土壤矿质养分和土壤微生物间的相互关系进行了主成分分析与典范相关分析。结果表明: 沿草丛、灌丛、次生林、原生林的顺向演替发展, 重要值(importance value, IV)>10.00的科、属、种及物种多样性最大值出现在次生林, 群落结构最佳值出现在顶级群落原生林; 喀斯特峰丛洼地景观异质性高, 各生态系统影响因子不同, 土壤微生物在喀斯特脆弱生态系统处于主导地位, 其次为灌丛; 不同集团因子的典范相关分析表明, 植物多样性指标与土壤氮素、Al₂O₃、Fe₂O₃、土壤微生物生物量碳(C_mic)、真菌和细菌关系密切。因此, 在喀斯特脆弱生态系统恢复与重建过程中, 应针对不同生态系统制定相应的培育管理措施。     

典型喀斯特峰丛洼地不同植被恢复对土壤养分含量和微生物多样性的影响

以桂西北典型喀斯特峰丛洼地植被恢复过程中草丛、灌丛、次生林、原生林4个植被恢复阶段为研究对象,通过测定优势种的根际与非根际的土壤p H、养分含量及微生物多样性,探讨不同恢复阶段根际土壤养分的富集效应及土壤微生物多样性的变化特征。研究结果表明:(1)4个恢复阶段的根际与非根际土壤养分均呈现显著差异;土壤有效态养分较全量养分对植物根际微小的变化响应更为灵敏;大多数养分表现出明显的富集效应,AP和AK在原生林的富集率明显高于其他恢复阶段;(2)4个恢复阶段细菌Shannon-Wiener指数(H)、丰富度指数(S)均高于真菌,根际土壤细菌与真菌Shannon-Wiener指数(H)、丰富度指数(S)与Pielou均匀度(EH)都高于非根际土壤;(3)4个恢复阶段土壤TN分别与p H、SOC、AN呈极显著正相关(P0.01),磷素、钾素与土壤微生物多样性呈显著相关(P0.05)。可研究结果为西南喀斯特脆弱区土壤生态功能恢复与植被恢复重建提供科学依据。     

桂西北喀斯特峰丛洼地表层土壤养分时空分异特征

本文运用传统统计方法研究了典型喀斯特峰丛洼地4个植被演替阶段(草地、灌木林、次生林、原生林)表层(0—15 cm)土壤养分的空间分异特征,并分析其成因。结果表明：(1)不同植被演替阶段土壤养分（有机碳、全氮、碳氮比、全磷、全钾、碱解氮、速效磷、速效钾）及pH值有明显差异（P<0.05）;除全钾外,其他养分含量均随植被正向演替而增加。(2)地貌部位对养分含量的影响不尽一致：各植被演替阶段的磷、钾及原生林的碳氮均符合养分的“洼积效应”,只有受人为干扰较强的草地、灌木林、次生林的碳氮养分存在随坡位升高而增加的现象。通过本研究得知,植被演替对养分积累具有积极作用;磷素（速效磷3.55—11.41 mg/kg）、钾素（速效钾64.05—105.75 mg/kg）是该区域的养分限制性因子;该区域养分的“倒置现象”并不普遍存在。     

不同土地利用方式下喀斯特峰丛洼地土壤微生物群落特征

基于对喀斯特峰丛洼地6种土地利用类型(坡耕地、草丛、灌丛、人工林、次生林、原生林)的土壤微生物、养分、矿物质和植被4组变量35个指标的调查分析,研究了不同土地利用方式下土壤微生物种群数量、微生物生物量C、N、P及其分形特征,以及土壤微生物与植被、土壤养分、矿物质的关系.结果表明:不同土地利用方式下喀斯特峰丛洼地的土壤微生物种群数量及组成不同.微生物种群数量均以原生林和坡耕地最高,人工林最低;3种森林土壤的细菌比率较大,坡耕地、草丛、灌丛的放线菌比率较大,真菌的比率均很小;土壤微生物生物量C、N、P的含量均很高,其中原生林最高;土壤微生物生物量碳与土壤微生物种群数量具有良好的分形关系,而土壤微生物生物量氮、磷与种群数量不存在分形关系;土壤微生物与植被、土壤养分、土壤矿物质显著相关,其中土壤微生物生物量碳与乔木层的Shannon指数、土壤速效氮、Fe₂O₃、CaO含量显著相关.     

喀斯特峰丛洼地不同退耕还林还草模式的土壤微生物特性

以坡耕地为对照,研究了喀斯特峰丛洼地任豆、香椿、板栗、柑橘、任豆+桂牧1号、桂牧1号和撂荒7种常见退耕还林还草模式下土壤微生物种群数量、微生物量碳氮磷及其分形特征和主要土壤酶活性特征。结果表明,不同退耕还林还草模式土壤微生物种群数量组成不同,除任豆模式外其他退耕还林还草模式均能提高土壤微生物总数量;不同退耕还林还草模式(除任豆模式外)土壤微生物量碳(MB_C)含量极显著增加,撂荒地最高,土壤微生物量氮(MB_N)含量变化范围不大,呈下降趋势,土壤微生物量磷(MB_P)含量的变异很大,香椿、板栗、撂荒和桂牧1号模式显著或极显著高于坡耕地;土壤MB_C与细菌数量的关系最相关(D=-4.07,R=0.81,P<0.01),其次为MB_C与放线菌数量(D=3.82,R=0.44,P<0.05),再次为MB_N与真菌数量(D=0.58,R=0.61,P<0.01),MB_C与真菌数量、MB_N与细菌、放线菌数量以及MB_P与细菌、真菌、放线菌数量之间不存在分形关系;不同退耕还林还草模式(除桂牧1号模式外)均显著或极显著增加了土壤蔗糖酶、脲酶和磷酸酶活性。总之,不同退耕还林还草模式均改善了土壤微生物特性,为喀斯特峰丛洼地脆弱生态系统恢复与重建提供了重要依据。     

喀斯特峰丛洼地不同生态系统的土壤肥力变化特征

基于喀斯特峰丛洼地坡耕地、草丛、灌丛、人工林、次生林、原生林6种典型生态系统的土壤主要养分、矿质养分和微生物这3组变量共计20个指标的调查、取样和分析,运用多重比较分析、主成分分析和典范相关分析探讨了其土壤肥力变化特征、主要影响因子及两两之间的相互关系。结果表明,喀斯特峰丛洼地土壤pH值为6.60—7.75,土壤主要养分、微生物种群数量和微生物生物量明显高于同纬度地区地带性红壤,矿质养分含量相对较低,其中SiO2、Al2O3、Fe2O3占矿质全量的90%以上。土壤肥力的总体趋势为原生林>次生林>灌丛>草丛>坡耕地>人工林。喀斯特石漠化地区实行林草结合的退耕还林还草模式更有利于土壤生态系统的环境改善,坡耕地应多施有机肥和氮肥,人工林应多施氮肥。原生林植物与养分之间达到了良好的平衡状态,主要应加强森林抚育管理,改善森林环境,保障植物、土壤养分及微生物之间的良好协调关系。确保土壤资源的合理利用,促进喀斯特峰丛洼地乃至整个西南喀斯特区域植被的迅速恢复和生态重建。     

喀斯特峰丛洼地植被演替过程中土壤养分的积累及影响因素

以桂西北环江县典型喀斯特峰丛洼地为对象,利用空间代替时间的方法,于2009年分析了植被演替过程中表层土壤(0～15 em)养分的变化及其主要控制因素.结果表明:随着植被正向演替(草地-灌丛-次生林-原生林),表层土壤的有机碳、全氮和全磷等含量显著增加,分别由演替初期(草地)的29.1、2.48和0.72 g·kg-1增加为演替后期(原生林)的73.9、8.10和1.6g·kg-1.土壤阳离子交换量与有机碳和全氮密切相关,是喀斯特土壤C、N积累的主要控制因素;凋落物中的P含量、C/P和N/P是土壤全磷积累的主要控制因素,较高的凋落物P含量、N/P以及较低的C/P有利于土壤中P的积累;而坡度、坡向和裸岩率等地形因子对土壤养分的影响较小.     

喀斯特峰丛洼地不同类型森林养分循环特征

以中国西南喀斯特峰丛洼地为研究区域用标准木法和收获法对人工林、次生林、原生林3个不同类型森林的6个代表性群落的生物量、营养元素生物循环量及循环特征进行了研究。结果表明:(1)不同类型森林群落乔木各器官的养分含量大小顺序为:叶枝根干,林下植被层和凋落物层的养分含量比较高,其含量普遍高于乔木层各组分,仅次于乔木叶片;各组分中营养元素以K、Ca最高,P、Mg最低;(2)3种类型森林间乔木层的养分积累量总规律表现为原生林(4540.30 kg/hm~2)次生林(2107.09 kg/hm~2)人工林(719.51 kg/hm~2),分别占林分养分积累量的88.30%、79.57%和62.60%;(3)3种类型森林生态系统养分总贮量相差不大,均主要集中在土壤层在各层分配格局有所差异;营养元素的年吸收量和年归还量均为次生林原生林人工林,年吸收量分别为:418.80、271.17和148.79 kg hm~(-2)a~(-1);年归还量分别为:182.98、111.43和43.37 kg hm_(-2)a~(-1);(4)不同类型森林养分利用系数总规律为人工林(0.35)次生林(0.20)原生林(0.10);循环系数则相反,为原生林(0.48)次生林(0.46)人工林(0.30);而周转时间为原生林(37.32)人工林(18.63)次生林(13.93)。喀斯特峰丛洼地土层薄,养分贮存能力差,森林养分循环能力相对较弱,沿着强、中、弱干扰递减梯度,3种类型森林养分利用效率和循环能力呈增长趋势。     

喀斯特峰丛洼地土壤矿物质的组成特征与作用

基于喀斯特峰丛洼地农作区、人工林、次生林、原生林4类典型生态系统动态监测样地(200 m×40 m)土壤矿质养分因子(7个)、植被(9个)、地形(4个)、土壤理化性状(10个)共计30个指标的全面调查取样分析,采用经典统计分析、主成分分析和典范相关分析探讨了土壤矿物质的组成特征、作用以及与植被、地形、其他土壤性状的耦合关系.结果表明： 喀斯特峰丛洼地土壤矿物质组成以SiO2、Al2O3、K2O、Fe2O3为主,明显低于全球土壤平均背景值和同区域地带性红壤,CaO、MgO含量居中,MnO含量很低;不同生态系统土壤矿物质组成和变异不同,土壤的发育程度也不同,植被和土壤的原生性呈同比正相关,均有潜在的石漠化风险;4类生态系统景观异质性高,主成分分析的降维效果不好,土壤矿物质均为各生态系统的主要影响因子,且与植被、地形、其他土壤性状的关系非常密切,特别是SiO2、CaO和MnO,其中对植被的影响主要是物种多样性,对土壤则为有机质、全氮、全钾等主要养分.土壤矿物质是影响喀斯特峰丛洼地土壤肥力和植物生长发育的限制因子之一,有效利用矿物质资源、合理施用矿质养分对喀斯特退化生态系统的恢复与重建作用重大.     

桂西北喀斯特峰丛洼地不同植被演替阶段的土壤脲酶活性

以桂西北喀斯特峰丛洼地不同演替阶段植被群落为研究对象,采用空间代替时间序列的方法,选取立地条件基本相似的草地、乔灌林和次生林3种次生演替植被,并以原生林为对照,通过野外调查取样和室内分析,探讨植被不同演替阶段土壤脲酶活性的变化特征及其与土壤理化性质的关系。结果发现,(1)不同植被演替阶段的土壤脲酶活性存在显著差异,草地最高(0.462 mg · g^-1 · d^-1),次生林次之(0.410 mg · g^-1 · d^-1),灌木林再次(0.371 mg · g^-1 · d^-1),原生林最低(0.194 mg · g^-1 · d^-1);(2)在喀斯特区域,土壤脲酶活性与全钾、粘粒含量、容重、碳氮比(C/N)、碱解氮占全氮的比例(AN/TN)呈正相关(P<0.01),与其他指标,如有机碳、全氮、碱解氮、微生物碳、微生物氮等均呈极显著负相关(P<0.01);(3)与脲酶活性关系密切的理化性质有全氮、碱解氮、微生物量、粘粒含量及C/N、AN/TN等。并不是所有区域的土壤脲酶活性都与SOC、TN、AN、微生物量呈正相关,当土壤养分较高,即土壤中的氮量不再是作物生长的限制因子时,脲酶活性有可能与之呈负相关。     

喀斯特峰丛坡地不同土地利用方式下土壤N、P空间变异特征

基于网格点(5 mx5 m)采样法采集土壤样品,利用经典统计学和地统计学方法,研究了喀斯特峰丛坡地不同土地利用方式(火烧迹地、刈割地、草地、封育地)下表层(0～20cm)土壤氮、磷的空间变异特性.结果表明:研究区4种不同土地利用方式土壤全氮(TN)、全磷(TP)、速效氮(AN)、速效磷(AP)均为中等程度变异,含量分别为5.40 ～6.26 g·kg-1、1.24 ～1.44 g·kg-1、365.87～507.32 mg·kg-1、3.91 ～8.04 mg·kg-1,封育地、火烧迹地土壤质量优于草地和刈割地;4种土地利用方式中火烧AN、火烧AP、刈割AN、封育TN的半方差函数最佳拟合模型为球状模型,火烧TN、刈割TN、刈割AP最佳拟合模型为指数模型,其他指标的最佳拟合模型均为高斯模型.刈割TP、火烧TP、草地TP、刈割TN、火烧AP、草地AP、封育TP表现为强烈的空间自相关性,其他土壤养分表现为中等的空间自相关.4种土地利用类型土壤TN与AN、TP与AP具有相似的空间分布格局.火烧、刈割处理TN和AN呈凹形分布,TP和AP呈单峰分布特征,中下坡含量最高,往两端含量逐渐降低;草地TN、AN、TP、AP 4种养分含量均随着坡位的升高而降低;封育样地中4种养分呈类似凹形分布,中间含量低,两端略微升高.土地利用方式的变化改变了喀斯特峰丛坡地土壤养分质量,造成了土壤养分空间格局的变化,因此,在地形破碎、土层浅薄的喀斯特地区进行生态恢复与重建时,应采取合理土地利用方式,进行保护和适度开发,提高喀斯特退化生态系统土壤质量.     

贵州中部喀斯特山地不同植被生态系统细根生态特征及养分储量

为了解喀斯特生态系统退化过程中树木细根生物量和土壤养分的变化,选择贵州中部喀斯特山地乔木林、灌木林和灌草丛3种植被生态系统,比较分析不同深度(0～5 cm、5～10 cm和10～15 cm)土壤细根数量及其养分情况.结果表明:树木细根主要分布在0～10 cm土层,并随土层加深而减少.在0～10 cm土层中,乔木林、灌木林和灌草丛的活细根生物量分别占0～15 cm总细根生物量的42.78%、56.75%和53.38%,总活细根生物量的83.36%、86.91%和93.79%.不同植被下优势种植物细根生物量存在差异.0～5 cm土层乔木林活细根氮素和磷素储量均显著高于灌草丛和灌木林(P0.05),但灌木林和灌草丛间没有差异;5～10 cm土层乔木林活细根氮和磷储量显著高于灌草丛和灌木林(P0.05),灌木林下又显著高于灌草丛下(P0.05).0～10 cm土层的活细根生物量与植株地上部分生物量呈正相关,植物叶片氮、磷养分含量与细根比根长呈显著的负相关,说明细根的养分储量对地上生物量的建成和生态系统功能的发挥具有重要作用.     

Stoichiometric relationships among producers,consumers and nutrient cycling in pelagic ecosystems

Most ecosystem models consolidate members of food-webs, e.g. species, into a small number of functional components. Each of these is then described by a single state variable such as biomass. When a multivariate approach incorporating multiple substances within components is substituted for this univariate one, a stoichiometric model is formed. Here we show that the Nitrogen:Phosphorus ratio within zooplankton herbivores varies substantially intraspecifically but not intraspecifically. By using stoichiometric theory and recent measurements of the N:P ratio within different zooplankton taxa, we calculate large differences in ratios of nutrients recycled by different zooplankton species. Finally, we demonstrate that N:P stoichiometry can successfully account for shifts in N- and P-limitation previously observed in whole-lake experiments. Species stoichiometry merges food-web dynamics with biogeochemical cycles to yield new insights.Abbreviations b N:P in zooplankton biomass - f N:P in algal biomass - L maximum accumulation eficiency - N:P ratio of nitrogen to phosphorus (moles:moles) - s N:P supply ratio from grazers - TN Total nitrogen = seston N + dissolved N (µmoles/liter) - TP Total phosphorus = seston P + dissolved P (µmoles/liter)     

Root decomposition and soil nutrient and carbon cycling in two temperate fen ecosystems

Although root litter contributes to a large extent to soil organic matter accumulation in peatlands, decomposition of root litter is often neglected in studies on litter decomposition and carbon and nutrient cycling in these ecosystems. In this study, decomposition of root and rhizome litter of Carex diandra and Carex lasiocarpa was determined in two temperate fens, one dominated by Sphagnum species ( Sphagnum fen; soil pH=4.4) and one without a Sphagnum cover ( Carex fen; soil pH=5.7). One-year mass loss increased in the order: roots Carex diandra 相似文献   

湿润和干旱条件下喀斯特地区洼地表层土壤水分的空间变异性

在桂西北喀斯特洼地,用地统计学方法研究了旱季初期湿润和干旱条件下表层（0—5和5～10cm）土壤水分的空间结构及其分布特征．结果表明,表层土壤水分存在明显的空间异质性和各向异性,呈现差异显著的斑块状分布格局．湿润条件下,土壤水分具有中等和较强的空间相关性,变程分别为33．15n,和15．75m,其中0～5cm层具有明显的趋势效应;干旱条件下,土壤水分则呈现出强烈的空间相关性,而且相似斑块的空间尺度有所减小,变程最小仅为8．22m;在平均含水量较低时（干旱条件）其变异程度较大,实际应用中应根据平均含水量水平采取不同的取样设计．实验区表层土壤水分空间变异及其分布格局的显著差异,主要是受地貌、平均含水量（降水）和地形等因素的影响．     

Litterfall and litter nutrient dynamics under cocoa ecosystems in lowland humid Ghana

There have been few studies quantifying litterfall, standing litterstock and gross litter decomposition following forest conversion to plantation crops such as cocoa. Additionally, an assessment of changing processes occurring in forest floor litter systems with plantation age is lacking. We investigated litterfall production, standing litter changes and litter decomposition along a chronosequence of shaded cocoa farm fields (secondary forest, 3, 15 and 30-year-old) in the moist semi-deciduous forest belt in the Ashanti Region of Ghana in West Africa over 24 months. Mean annual litterfall production differed significantly among study sites and ranged from 5.0 to 10.4 Mg DM ha^?1. Similarly, standing litter differed significantly between land-use /plot ages. The results showed significant differences in quality between litter from forest and litter from cocoa plantations. Litterfall from forests had higher concentrations of nitrogen and lower concentration of soluble polyphenols and lignin compared to litter from cocoa systems. Monthly decomposition coefficients (k) estimated as $ k = {{\left( {{\text{A}} - \left( {{\text{L}}_1 - {\text{L}}_0 } \right)} \right)} \mathord{\left/ {\vphantom {{\left( {{\text{A}} - \left( {{\text{L}}_1 - {\text{L}}_0 } \right)} \right)} {\left( {{{\left( {{\text{L}}_1 + {\text{L}}_0 } \right)} \mathord{\left/ {\vphantom {{\left( {{\text{L}}_1 + {\text{L}}_0 } \right)} 2}} \right. } 2}} \right)}}} \right. } {\left( {{{\left( {{\text{L}}_1 + {\text{L}}_0 } \right)} \mathord{\left/ {\vphantom {{\left( {{\text{L}}_1 + {\text{L}}_0 } \right)} 2}} \right. } 2}} \right)}} $ , where A is litterfall production during the month, L₀ is the standing litterstock at the beginning of the month and L₁ is the standing litterstock at the end of the month. Annual decomposition coefficients (k _L ) were similar in cocoa systems (0.221–0.227) but higher under secondary forests (0.354). Correlations between litter quality parameters and the decomposition coefficient showed nitrogen and lignin concentrations as well as ratios that include nitrogen are the best predictors of decomposition for the litters studied. Our results confirm the hypothesis that decomposition decreases following forest conversion to shaded cocoa systems because of litter quality changes and that decomposition rates correlate to litter quality differences between forest and cocoa ecosystems. The study also showed that standing litter pools and litterfall production in recently converted cocoa plantations are low compared to secondary forests or mature cocoa systems. Management strategies involving the introduction of upper canopy species during plantation development with corresponding replacement of tree mortality with diverse fast growing species will provide high quality and quantity litter resources.     

Optimal allocation of building blocks between nutrient uptake systems in a microbe

 A bacterial cell must distribute its molecular building blocks among various types of nutrient uptake systems. If the microbe is to maximize its average growth rate, this allocation of building blocks must be adjusted to the environmental availabilities of the various nutrients. The adjustments can be found from growth balancing considerations. We give a full proof of optimality and uniqueness of the optimal allocation regime for a simple model of microbial growth and internal stores kinetics. This proof suggests likely candidates for optimal control regimes in the case of a more realistic model. These candidate regimes differ with respect to the information that the cells control system must have access to. We pay particular attention to one of the three candidates, a feedback regime based on a cellular control system that monitors only internal reserve densities. We show that allocation converges rapidly to balanced growth under this control regime. Received: 20 November 2000 / Revised version: 7 August 2001 / Published online: 21 February 2002     

The effect of parent material and soil development on nutrient cycling in temperate ecosystems

The parent material of a soil determines the original supply of those nutrient elements that are released by weathering and influences the balance between nutrient loss and retention. Organic acids and exudates produced by microorganisms and plants enhance the weathering of minerals and the release of nutrients. Nutrients may be stored in organic cycles or as ions adsorbed to clay and organic matter. Nutrients are lost mainly by leaching, both as dissolved ions and when associated with soluble organic components. Soil formation evidently affects these processes and modifies the environment at different depths as soil horizons develop. Strong interactions between mineral and organic colloids occur where most residues are added below ground, as in grasslands, or mixed with mineral soil by faunal activity, as in some forests. These systems tend to be nutrient conserving. The addition of organic residues to the soil surface often results in slow decomposition, the tie-up of many nutrients in biologically resistant humic materials, and the generation of organic acids that are active in leaching and chelation. These soils tend to lose nutrients by leaching and become strongly acidic with time. Leaching is strongest in uplands with net downward flows to deep water tables, and may be dampened or obviated in lowlands with strong upward fluxes due to artesian pressure or capillary rise from a water table that is close to the surface. Pedogenic features such as clayeyB horizons or duripans may alter water flow. Simonson's concepts that all basic soil-forming processes occur to some degree in all soils are critical to developing models describing soil formation and nutrient cycles.     

On the relationship between nutrient use efficiency and fertility in forest ecosystems

The concept of nutrient use efficiency is central in understanding ecosystem functioning because it is the step in which plants can influence the return of the nutrients to the soil pool and the quality of the litter. There are several ways to define nutrient use efficiency, but a common way within ecosystem ecology is as the ratio of litterfall production per unit nutrient to the litterfall nutrient content. However, this ratio is not a valid measurement to examine nutrient use efficiency in relationship to ecosystem fertility because there is a strong autocorrelation between litterfall dry mass per unit of nutrient and the amount of nutrients. More appropriate statistical analysis of the relationship between the fertility of ecosystems and the amount of nutrients in the litterfall are inconclusive, but indicate that, at least in some cases, there is (1) no pattern, (2) higher nutrient use efficiency at intermediate-fertility sites or (3) higher efficiency at higher-fertility sites. There is, however, no indication that nutrient use efficiency is greater in nutrient-poor ecosystems. This conclusion has important consequences for ecosystem nutrient cycling. Given the lack of a clear, consistent relationship between site fertility and litterfall nutrients, there is little likelihood that such a feedback mechanism plays an important role in ecosystem nutrient cycling. Received: 22 January 1996 / Accepted: 26 December 1996     

喀斯特峰丛洼地土地利用演变及其土壤侵蚀效应

人类不合理活动所导致的土地利用演变是引发土壤侵蚀及其负面生态效应的主要机制,因此研究二者的耦合关系具有重要意义。本文以贵州普定县的石人寨峰丛洼地为主要研究区域,从景观生态学的"格局-过程-尺度"、"源、汇景观"原理及其景观空间负荷对比指数(LCI)出发,应用稳定同位素和放射性核素示踪方法,揭示土地利用演变及其土壤侵蚀特征,并进一步分析二者的耦合关系。结果表明,该洼地在土壤剖面约100cm处记录到坡地森林遭受砍伐后变为耕地的事件,随后从坡地侵蚀下来的大量土壤沉积于洼地底部;该事件之后进入垦殖期,在洼地中轮种玉米、油菜、大豆等农作物。本研究为优化当地土地利用结构,改善流域的水土流失状况提供了新的视角。