A Fractal Method of Estimating Soil Structure Changes Under Different Vegetations on Ziwuling Mountains of the Loess Plateau, China

Fractal method is a new method to estimate soil structure. It has been shown to be a useful tool in studies related to physical properties of soil as well as erosion and other hydrological processes. Fractal dimension was used to study the soil structure in soil at different stages of vegetative succession on the Ziwuling Mountains. The land use and vegetation types included cultivated land, abandoned land, grassland, two types of shrub land, and three types of forests. The grassland, shrub land, and forested areas represented a continuum in vegetative succession that had occurred naturally, as the land was abandoned in 1862. Disturbed and undisturbed soil samples were collected from ten vegetation types from depths of 0-10, 10-20, and 20-30 cm on the Ziwuling Mountains, at a site with an elevation of about 1 500 m. Particle size distribution was determined by the pipette method and aggregate size distribution was determined by wet sieving. The results were used to calculate the particle and aggregate fractal dimension. The results showed that particle and aggregate fractal dimensions varied between vegetation types. There was a positive correlation between the particle fractal dimension and the weight of particles with diameter 〈 0.001 mm, but no relationship between particle fractal dimension and the other particle size classes. Particle fractal dimension was lower in vegetated soils compared to cropland and there was no consistent relationship between fractal dimension and vegetation type. Aggregate fractal dimension was positively correlated with the weight of 〉 0.25 mm aggregates. Aggregate fractal dimension was lower in vegetated soils compared with cropland. In contrast to particle fractal dimension, aggregate fractal dimension described changes in soil structure associated with vegetative succession. The results of this study indicate that aggregate fractal dimension is more effective in describing soil structure and function compared with particle fractal dimension.     

Effect of Different Irrigation Methods on Dissolved Organic Carbon and Microbial Biomass Carbon in the Greenhouse Soil

The objective of this study was to investigate the contents and distribution of dissolved organic carbon （DOC） and microbial biomass carbon （MBC） at 0-100 cm soil depth under three irrigation treatments, viz., subsurface, drip and furrow irrigation in the greenhouse soil. The soil samples were collected at different depths （0-100 cm）, and the contents of soil total organic carbon （TOC）, DOC and MBC were analysed. The experiment was conducted for 10 yr, during which period the application of fertilizers and crop management practices were kept identical. The results showed that the contents of TOC, DOC and MBC were significantly affected by different irrigation regimes, decreased with the increase of soil depth. TOC at 0-10 and 80-100 cm soil depths followed the order of furrow irrigation 〉 subsurface irrigation 〉 drip irrigation, whereas at the depth of 10-80 cm followed the order of subsurface irrigation 〉 furrow irrigation 〉 drip irrigation. DOC and MBC contents at 0-100 cm soil depths followed the order of furrow irrigation 〉 drip irrigation 〉 subsurface irrigation, and drip irrigation 〉 furrow irrigation 〉 subsurface irrigation, respectively. The ratios of DOC and MBC to TOC accounted for 4.98-12.87% and 1.48-2.82%, respectively, which were the highest in the drip irrigation treatment, followed were in the furrow irrigation treatment, and the lowest in subsurface irrigation treatment. There were significant positive correlations among the contents of DOC, MBC and TOC in all irrigation treatments. The furrow irrigation facilitated the accumulation of TOC and DOC, while drip irrigation increased the MBC. The content of TOC and the ratios of DOC to TOC were the lowest in subsurface irrigation treatment.     

Variation in soil properties in a transformed ecosystem in Southwestern Nigeria

Variation in soil properties as a result of the conversion of the tropical rainforest to a monospecific plantation of teak, tectona grandis, was examined in Akure forest reserve in Southwestern Nigeria. Comparison was made in the active rooting zone of 50 cm soil depth. It was discovered that there were no significant differences in the physical properties except in the value of organic matter content at the top 10 cm layer but chemical properties such as the pH and organic carbon changed significantly at the top 10 cm layer. Differences in other chemical properties, such as the available P, exchangeable cations K, Ca and Mg, the exchangeable acidity and the cation exchange capacity were minor. This showed that no nutrient was limiting or was likely to be limiting in the soil for subsequent short rotation of plantation development.     

Bacterial diversity and community composition changes in paddy soils that have different parent materials and fertility levels

Parent materials and the fertility levels of paddy soils are highly variable in subtropical China. Bacterial diversity and community composition play pivotal roles in soil ecosystem processes and functions. However, the effects of parent material and fertility on bacterial diversity and community composition in paddy soils are unclear. The key soil factors driving the changes in bacterial diversity, community composition, and the specific bacterial species in soils that are derived from different parent materials and have differing fertility levels are unknown. Soil samples were collected from paddy fields in two areas with different parent materials(quaternary red clay or tertiary sandstone) and two levels of fertility(high or low). The variations in bacterial diversity indices and communities were evaluated by 454 pyrosequencing which targeted the V4–V5 region of the 16 S r RNA gene. The effects of parent material and fertility on bacterial diversity and community composition were clarified by a two-way ANOVA and a two-way PERMANOVA. A principal coordinate analysis(PCo A), a redundancy analysis(RDA), and multivariate regression trees(MRT) were used to assess changes in the studied variables and identify the factors affecting bacterial community composition. Co-occurrence network analysis was performed to find correlations between bacterial genera and specific soil properties, and a statistical analysis of metagenomic profiles(STAMP) was used to determine bacterial genus abundance differences between the soil samples. The contributions made by parent material and soil fertility to changes in the bacterial diversity indices were comparable, but soil fertility accounted for a larger part of the shift in bacterial community composition than the parent material. Soil properties, especially soil texture, were strongly associated with bacterial diversity. The RDA showed that soil organic carbon(SOC) was the primary factor influencing bacterial community composition. A key threshold for SOC(25.5 g kg~(–1)) separated low fertility soils from high fertility soils. The network analysis implied that bacterial interactions tended towards cooperation and that copiotrophic bacteria became dominant when the soil environment improved. The STAMP revealed that copiotrophic bacteria, such as Massilia and Rhodanobacter, were more abundant in the high fertility soils, while oligotrophic bacteria, such as Anaerolinea, were dominant in low fertility soils. The results showed that soil texture played a role in bacterial diversity, but nutrients, especially SOC, shaped bacterial community composition in paddy soils with different parent materials and fertility levels.     

Abundance and Community Composition of Ammonia-Oxidizers in Paddy Soil at Different Nitrogen Fertilizer Rates

Ammonia oxidation, the first and rate-limiting step of nitrification, is carried out by both ammonia-oxidizing bacteria （AOB） and ammonia-oxidizing archaea （AOA）. However, the relative importance of AOB and AOA to nitrification in terrestrial ecosystems is not well understood. The aim of this study was to investigate the effect of the nitrogen input amount on abundance and community composition of AOB and AOA in red paddy soil. Soil samples of 10-20 cm （root layer soil） and 0-5 cm （surface soil） depths were taken from a red paddy. Rice in the paddy was fertilized with different rates of N as urea of N1 （75 kg N ha＂ yr-1）, N2 （150 kg N ha~ yrl）, N3 （225 kg N ha1 yrl） and CK （without fertilizers） in 2009, 2010 and 2011. Abundance and community composition of ammonia oxidizers was analyzed by real-time PCR and denaturing gradient gel electrophoresis （DGGE） based on amoA （the unit A of ammonia monooxygenase） gene. Archaeal amoA copies in N3 and N2 were significantly （P〈0.05） higher than those in CK and N1 in root layer soil or in surface soil under tillering and heading stages of rice, while the enhancement in bacterial amoA gene copies with increasing of N fertilizer rates only took on in root layer soil. N availability and soil NO3--N content increased but soil NH4＋-N content didn＇t change with increasing of N fertilizer rates. Otherwise, the copy numbers of archaeal amoA gene were higher （P〈0.05） than those of bacterial amoA gene in root lary soil or in surface soil. Redundancy discriminate analysis based on DGGE bands showed that there were no obvious differs in composition of AOA or AOB communities in the field among different N fertilizer rates. Results of this study suggested that the abundance of ammonia-oxidizers had active response to N fertilizer rates and the response of AOA was more obvious than that of AOB. Similarity in the community composition of AOA or AOB among different N fertilizer rates indicate that the community composition of ammonia-oxidizers was relatively stable in the paddy soil at least in short term for three years.     

Effects of Cinnamic Acid on Bacterial Community Diversity in Rhizosphere Soil of Cucumber Seedlings Under Salt Stress

To investigate the effects of a plant autotoxin, cinnamic acid, on bacterial communities in the rhizosphere soil of cucumber seedlings under salt stress, we used cucumber as the experimental material, cinnamic acid as the autotoxin, and NaCl to apply salt stress. Bacterial communities in the rhizosphere soil were analyzed using polymerase chain reaction （PCR）, denaturing gradient gel electrophoresis （DGGE）, and clone sequencing. Salt stress decreased the diversity of bacterial species in rhizosphere soil of cucumber seedlings at several growth stages. Cinnamic acid exacerbated the effects of salt stress at high concentrations, but alleviated its effects at low concentrations. Cloning and sequencing results indicated that DGGE bands amplified from soil samples showed high homology to uncultured bacterial species. Cinnamic acid at 50 mg kg^-1 soil improved cucumber growth and was the most effective treatment to alleviate the effects of salt stress on bacterial communities.     

Studies on Fast Remediation of Soda Meadow Alkaline Soil

Researches on models of remediation quickly in soda meadow alkaline soil, and dynamic variation of water-salt in saline soil of Zhaozhou County were studied systematically from 2001 to 2006. Realize the vegetation cover of those years through the artificial planting, mixed seeding lyme grass （Elymus dahuricus Turcz） and melilot in the mode of rotary tillage and deep loosening in lower and medium saline soils. The results showed that there was remarkable relationship between net evaporation （difference of precipitation and evaporation） and total salt content in the soil. The net evaporation could be used as a new method to forecast the dynamics variation of salt to ensure the pasture optimum sowing time. Realize the autumnal vegetation cover of those years through direct planting on the bourgeon layer of soda meadow alkaline soil, on the other hand, the covered pasture made the function of restraining salt and alkaline content to realize the biology reverse succession quickly. Forage seeds were seeded directly on the seeding bed of soda alkaline meadow at the end of July. In fall of the same year, a certain amount of biomass was obtained. The model, which has remarkable economical efficiency and use widely, represented the innovative model for the fast vegetation restoration on the soda alkaline meadow soil.     

Role of Potassium Bearing Minerals in Desorption of Reserved Potassium in Some Soils of Northern Iraq

A laboratory study was conducted in order to explain successive extractions of reserved potassium by using concentrated HCI under reflux for 13 surface and sub-surface soil samples representing three chosen pedons of soil series （472 ECC Bashika, 463 EKC Rabeaa and 461 ECC Talafar） locations of Nineveh Province in Northern of Iraq. The aim is to investigate role of clay minerals on release of reserved potassium from soils. Results showed that dominated clay minerals were （smectite 〉 illite 〉 kaolinite 〉 chlorite） for both 472 ECC and 461 ECC soil series and were （illite 〉 smectite 〉 kaolinite 〉 chlorite） for 463 EKC soil series. Also results appeared that exchangeable K＋ released values were 2,483-4,575 mg/kg at 461 ECC and 463 EKC soil series, respectively; non-exchangeable phase ranged from 752-1,390 mg/kg at 461 ECC and 472 ECC soil series, respectively. Soil fertility was evaluated according to its K＋ mica release referring for high K＋ release content with range between 3,324-5,516 mg/kg at 461 ECC and 463 EKC soil series, but rate ofK~ released was very law according to parabolic diffusion me,del with range from 195-359 mg/kg at latter soil series respectively. Results reflect effect of clay minerals on potassium release as amount and rates in arid and semi-arid regions. It can be concluded the study soils have a high amount of potassium content with low rate release of it, in turn these soil need particular management.     

Shifts in soil bacterial communities induced by the controlled-release fertilizer coatings

Coated controlled-release fertilizers(CRFs) have been widely applied in agriculture due to their increased efficiency. However, the widespread and a lot of coated CRFs application may leave undesired coating residues in the soil due to their slow degradation. Limited information is available on the effects of substantial residual coatings on the soil bacterial community. By adding 0, 5, 10, 20, and 50 times quantities of residual coating from conventional application amount of resin and water-soluble coated CRFs, we studied the responses of soil properties and bacterial community composition to these two residual coatings in black soil. The results showed that the resin and water-soluble coatings did not essentially alter the properties of black soil or cause dramatic changes to bacterial diversity within the test concentration range. The residual resin and water-soluble coatings also did not distinctly alter the relative abundance of the top ten bacteria at phylum level. Heatmap results suggested that the treatments were basically clustered into two groups by concentration rather than types of coating material. Pearson correlation analysis showed that the Simpson's diversity index of the bacterial community was significantly correlated with microbial biomass carbon(MBC, r=0.394, P0.05), and the richness index abundance-based coverage estimator(ACE) of the bacterial community was significantly correlated with microbial biomass nitrogen(MBN, r=0.407, P0.05). Overall, results of this study suggested that substantial residual resin and water-soluble coatings with 0–50 times quantities of residual coating from conventional application amount of coated CRFs did not generate obviously negative impacts on the bacterial community in black soil.     

Soil Microbial Community Composition During Natural Recovery in the Loess Plateau, China

This study aimed to determine the characteristics of soil microbial community composition and its relationship with soil chemical properties during natural recovery in the Loess Plateau.The soil microbial community composition was analyzed by comparing the soil microbial phospholipid fatty acids（PLFAs） of eight croplands abandoned for 1,3,5,10,13,15,20,and 30 yr in the Dunshan watershed,northern Loess Plateau,China.The results showed that soil organic carbon,total nitrogen,soil microbial biomass carbon,and soil microbial biomass nitrogen significantly increased with the abandonment duration,whereas the metabolic quotient significantly decreased.The Shannon richness and Shannon evenness of PLFAs significantly increased after 10 yr of abandonment.Gram-negative,Gram-positive,bacterial,fungal,and total PLFAs linearly increased with increased abandonment duration.Redundancy analysis showed that the abandonment duration was the most important environmental factor in determining the PLFA microbial community composition.The soil microbial PLFAs changed from anteiso-to iso-,unsaturated to saturated,and short-to long-chain during natural recovery.Therefore,in the Loess Plateau,cropland abandonment for natural recovery resulted in the increase of the soil microbial PLFA biomass and microbial PLFA species and changed the microbial from chemolithotrophic to a more heterotrophic community.     

亚热带不同演替阶段森林土壤可溶性有机氮与酶活性特征

森林演替中的土壤氮素转化是生态系统的关键过程,其相互关系的研究正受到愈来愈多的重视,探讨土壤可溶性有机氮(SON)和酶活性对维持森林生态系统氮循环及植被恢复、森林生态系统管理有重要的意义。在湖南省长沙县大山冲森林公园不同演替阶段三种林地(针叶林、落叶阔叶林和常绿阔叶林)的1 hm~2长期观测样地,采集表层土壤样品,测定SON和葡糖胺糖苷酶、葡萄糖苷酶和木糖苷酶酶活性,分析亚热带常绿阔叶林演替序列森林土壤SON和酶活性特征,探讨其特征及其与土壤理化性质的关系。结果表明:森林土壤SON表现为常绿阔叶林落叶阔叶林针叶林,且针叶林的铵态氮(NH_4~+-N)、硝态氮(NO_3~--N)、微生物生物量氮(MBN)、总氮(TN)均低于常绿阔叶林和落叶阔叶林(P0.05);阔叶林土壤葡糖胺糖苷酶、葡萄糖苷酶和木糖苷酶明显高于针叶林,常绿阔叶林土壤与三种酶底物的亲和力最强,而落叶阔叶林土壤酶活性最高;冗余分析显示SON与三种酶活性均存在显著正相关关系,葡糖胺糖苷酶活性和亲和力与土壤TN、NH_4~+-N和MBN呈显著正相关。研究表明,亚热带不同演替阶段森林土壤SON和酶活性差异明显;SON随植被正向演替而增加,SON转化相关的酶活性亦随植被正向演替而增强。亚热带森林植被正向演替伴随着土壤氮素养分快速循环过程。     

武夷山针阔混交林的群落多样性

通过测定群落内乔木层的重要值、灌木层的Shannon-Wiener(H′)指数和Pielou(J)均匀度指数,以及郑元润改进后的M. Godron稳定性指数,对武夷山4个不同类型的针阔混交林群落进行所处演替阶段的分析和群落稳定性研究。结果表明：(1)群落A(杉木Cunninghamia lanceolata Hook.、马尾松Pinus massoniana Lamb.+赤杨叶Alniphyllum fortunei Makino.)处于从针叶林向针阔混交林演替阶段的中期;群落B(马尾松+细柄蕈树Altingia gracilipes Merr.)处于从阔叶马尾松林向阔叶混交林演替的中期;群落C(马尾松+甜槠Castanopsis eyrei Tutch.)处于从针阔混交林向阔叶混交林演替的中后期;群落D (杉木+赤杨叶)处于从针阔混交林向阔叶混交林演替的初期;(2)群落内灌木层的物种构成及多样性将影响并决定群落演替的方向;(3)4个针阔混交林乔木层仍有大量针叶树种存在,稳定性测定坐标值远离20/80这个点,表明这些森林群落均未达到顶级群落阶段,处于不稳定状态。     

海南甘什岭热带低地雨林不同演替阶段根系的生物量特征

热带地区植物根系生物量的研究对预测气候变化条件下土壤碳库的变化和热带雨林次生演替地下生态学过程的认识具有重要意义。在海南三亚市甘什岭自然保护区内,选取4个植被恢复阶段（草本群落、灌木群落、40 年次生林和60 年次生林）,利用平均标准木机械布点法采集0～100 cm根系样品,研究根系生物量、不同根系径级组成结构以及地下垂直分布规律。研究结果表明:（1）甘什岭热带低地雨林不同演替阶段根系生物总量在5.23～28.98 t·hm?2,植被恢复演替（正向）显著地增加了根系生物量,其中草本至灌木阶段不显著;（2）木本植物群落根系生物量以粗根（>2 mm）为主,最高占其总生物量的89.76%,草本则以细根（≤2 mm）为主,占其总生物量的53.53%以上;随着甘什岭植被的恢复,粗根占根系生物量的比例逐渐增加,细根占根系生物量的比例逐渐减小。（3）甘什岭热带低地雨林近80%的根系生物量集中分布在 0～20 cm 土层中,随着土壤剖面深度的增加,根系生物量大幅度减少,草本群落生物量在土壤剖面中的垂直变化规律呈指数回归,其余各恢复演替阶段呈幂函数回归。（4）根系生物量模型中,树高、D2H（胸径的平方与树高的乘积）与根系生物量拟合最好,在实践应用中,可根据林木的树高和D2H估测甘什岭地区植被根系生物量。本研究结果为进一步研究甘什岭热带低地雨林植物群落地下碳素分配及土壤碳库变化奠定基础,还可为估算我国热带低地雨林地区植被根系生物量和生产力提供参考。     

双峰山国家森林公园植被恢复过程中的种子库研究

对湖北双峰山国家森林公园不同类型植物群落土壤种子库的植物种类、密度及优势成分进行了研究,并结合群落植物种类,分析了该森林公园植被在生态恢复中的进程。结果表明,种子库中有植物30种,分属19科,其中绝大多数为草本植物;种子库储量为100～400粒/m2,其中上层土壤(0～5cm)种子数量占种子库总数的58.2%,种子库主要物种为莎草、淡竹叶、苎麻、绊根草、马唐等,地面植物与种子库植物的相似度不高,这表明双峰山国家森林公园植被正处于生态恢复的初级阶段。     

上海城市森林土壤理化性质

为了从植物群落角度探究城市森林土壤的理化性质,采集上海市中心城区（外环线以内）公园绿地、居住区绿地、单位附属绿地和道路绿地等4种功能区森林绿地的土壤,分6种群落类型（常绿阔叶林、落叶阔叶林、常绿针叶林、落叶针叶林、常绿灌木林和落叶灌木林）,3个土壤分层（0～10,10～20和20～30cm）进行理化性质测定。结果表明,30cm以上的土壤有机质平均质量分数为15．52g·kg^-1,属于低等水平;全氮和全磷质量分数分别为3．78和1．13g·kg^-1,属于中下水平。表层土壤中有机质和全氮质量分数均较高,随着剖面深度增加逐渐减小,磷质量分数未发现有递减性规律变化。土壤密度为1．44～1．60g·cm^-3,表明人类活动使上海城市绿地土壤的紧实度增大。针对上海森林土壤的状况,提高绿地土壤尤其是新建绿地土壤的肥力水平,以增强氮磷等营养元素质量分数;疏松土壤,以利于透气保水;乔、灌植被分层布局．能更好地增加城市森林土壤有机质并收到更好的景观效果。图4表3参25     

上海市林地土壤有机碳分布特征及其与土壤理化性质的关系

土壤有机碳影响着全球气候生态系统的平衡。城市林地作为城市生态系统的重要组成部分,其碳含量和密度的高低是评价城市生态环境建设成功与否的关键。以上海市7种典型林地樟树Cinnamomum camphora林、阔叶混交林、其他软阔林、其他硬阔林、针阔混交林、水杉Metasequoia glyptostroboides林、经济林为对象,分析了不同林地、不同土层（0~10,10~30,30~100 cm）的有机碳质量分数和密度分布特征,并采用Pearson相关性分析方法和逐步剔除回归法探讨了有机碳质量分数与土壤基本理化性质的关系。结果表明:①上海市林地0~100 cm土壤有机碳平均质量分数从大到小依次为:其他软阔林、樟树林、经济林、阔叶混交林、水杉林、针阔混交林、其他硬阔林。各林地土壤有机碳质量分数在0~10和10~30 cm存在显著差异（P < 0.05）。除经济林,其余林地土壤有机碳质量分数在垂直方向上均表现为逐渐降低。②上海市林地0~100 cm土壤有机碳密度从大到小依次为:樟树林、其他软阔林、经济林、阔叶混交林、针阔混交林、水杉林、其他硬阔林。上海市林地0~30 cm土层有机碳密度对0~100 cm土层的贡献率较低。③上海市7种林地土壤有机碳质量分数与全氮和碱解氮呈极显著正相关（P < 0.01）,与电导率、全磷的相关性不显著。樟树林、其他软阔林、其他硬阔林、水杉林的土壤有机碳质量分数与容重显著负相关（P < 0.05）。阔叶混交林、其他软阔林、其他硬阔林的土壤有机碳质量分数与pH值呈显著负相关（P < 0.05）;樟树林、水杉林的土壤有机碳质量分数与速效磷显著正相关（P < 0.05）。除阔叶混交林、水杉林的土壤有机碳质量分数的主要影响因子为全氮,樟树林、其他软阔林、其他硬阔林和针阔混交林的土壤有机碳质量分数变化的主控因子为碱解氮。     

杭州天然森林植被类型的调查研究

通过对杭州天然森林植被的调查研究,摸清了杭州森林植被的类型、分布特点,组成结构、生境条件,生产力状况及群落动态,阐述了保护杭州森林植被的重要意义,对森林植被的恢复和改造提出建设性意见。以群落外貌,树种生活型及重要值为依据进行数量化处理,划分植被类型,将杭州的次生林植被划分为7个植被型、2个植被亚型、10个群系。     

新疆喀纳斯旅游区森林群落次生演替与土壤肥力的关系

从土壤理化性质出发,利用多元统计方法和土壤肥力综合评价体系,对新疆喀纳斯旅游区森林群落次生演替过程中土壤肥力的变化特征进行了综合评价.结果表明,不同森林类型的土壤肥力综合指标值为阔叶林＞阔叶针叶混交林＞针叶阔叶混交林＞针叶混交林;不同森林演替阶段的土壤肥力综合指标值为演替前期＞演替中期＞演替后期.     

中条山混沟地区的原始森林分布和物种多样性特征研究

[目的]深入研究中条山混沟地区原始森林群落物种多样性。[方法]采用样方法取样,依据重要值指标运用双向指示种分析(TWINSPAN)法,将位于山西中条山东段的混沟原始森林植被群系分成10个群落。应用丰富度指数(N0),Simpson指数(λ),Shannon-Weiner指数(H′),均匀度指数(E1、E5)和相似性系数(Ss)研究了10个群落的植物种多样性。[结果]中条山混沟地区森林群落原始生态特征明显,10个群落相对稳定;10个群落间的多样性均表现出较大的差异,乔木层的多样性指数变幅在0.345~2.093;生境的异质性导致群丛的种类组成和结构差异,10个群丛种类成分的相似性均小于0.5,群落物种相似性较高。[结论]该研究为进一步揭示原始森林的形成和发展及预测原始森林的演替趋势提供科学依据。     

皆伐油松人工林天然更新对土壤肥力和酶活性的影响

目的探讨油松人工林皆伐后天然更新成林的过程中对土壤肥力和酶活性的影响,分析植物群落演替过程中土壤质量的变化规律,为油松林的地力维护和可持续经营提供理论依据。方法采用演替时序法,在河北平泉地区选择立地条件一致的中龄林（32年）、近熟林（40年）、成熟林（53年）,皆伐后不同时间（5年、10年、24年）的天然更新林及皆伐后8年撂荒地作为对照,分0 ~ 10 cm、10 ~ 20 cm土层测定土壤肥力和酶活性,并对2组指标进行典型相关分析。结果（1）从中龄林到成熟林土壤质量持续提升,其中在0 ~ 10 cm土层土壤含水量、全氮含量和蔗糖酶活性分别提高了161.5%、379.1%和181.3%,各指标在10 ~ 20 cm土层也有显著提升（P < 0.05）。（2）皆伐后5年天然更新林与成熟林相比土壤肥力和酶活性差异不显著（P > 0.05）,到伐后24年土壤肥力和酶活性逐渐下降,与伐后5年相比,土壤毛管持水量、全氮含量和蔗糖酶活性在0 ~ 10 cm土层分别下降了24.4%、61.0%和28.8%,在10 ~ 20 cm土层各指标也均有明显下降（P < 0.05）,但伐后24年土壤肥力和酶活性仍高于中龄林和近熟林。（3）天然更新林的土壤肥力和酶活性显著高于撂荒地（P < 0.05）,天然更新林在0 ~ 10 cm土层土壤毛管持水量、有机质含量和脲酶活性相比撂荒地分别提高了43.7%、145.7%和116.6%,在10 ~ 20 cm土层各指标也显著高于撂荒地（P < 0.05）。（4）典型相关分析表明土壤酶活性与土壤肥力之间具有极显著相关性（P < 0.01）,土壤肥力主要受土壤密度、毛管持水量、毛管孔隙度、有机质、全氮的影响,而土壤酶活性主要受脲酶和蔗糖酶的影响。土壤肥力和酶活性的典型变量得分均表现为成熟林 > 伐后5年 > 伐后10年 > 伐后24年 > 近熟林 > 撂荒地 > 中龄林。结论油松人工林成熟林阶段土壤质量明显改善,随着时间推移皆伐会造成一定程度的土壤肥力和酶活性下降,但在皆伐迹地上及时实现植被恢复会显著减轻下降的程度,且土壤质量明显好于同一发育阶段的人工林。皆伐油松人工林天然更新可以有效地缓解地力衰退的问题。