巨尾桉林地土壤化学性质变化分析

通过对福建省长泰县一块巨尾桉林地18 a经营前后土壤各种养分指标的比较,揭示桉树林地长期经营对土壤肥力的影响,结果表明：土壤有机质、养分全量及交换性钙、镁、碱解氮等都有不同程度提高,而速效钾、pH值和速效磷等有所降低,分析认为杂交桉主要靠杂交优势而非靠消耗地力获得增产,杂交桉林地养分循环良好,土壤有机质增加,土壤供肥潜力提高;现有速效钾、pH值为林地正常值,18 a前测定的为炼山造林后的样品数据,草木灰（K2CO3）渗入土壤所致,速效磷降低为杂交桉对其需求量较大所致;建议在桉树人工林经营过程中应注意补充磷肥和钙肥。     

木麻黄连栽对沿海沙地土壤养分含量及酶活性的影响

选择东山 1代、2代和惠安 1代、2代、3代林分为研究对象 ,分别采集土壤进行对比研究。结果表明 ,木麻黄多代连栽后 :( 1 )随着栽植代数的增加 ,沙地土壤的pH值表现为降低趋势 ,而土壤的水解性总酸度、交换性总酸度、交换性氢和交换性铝含量等指标随着木麻黄连栽代数的增加而增大 ;( 2 )沙地土壤中水解性氮、铵态氮、有效磷、速效钾、全碳和全氮的含量随着代数的增加而降低 ,而且木麻黄连栽对表层土壤中上述养分的降低更为显著 ,但木麻黄连栽对缓效钾的影响并不明显。 ( 3 )土壤中阳离子交换总量逐代增大 ,这主要与交换性钙和水解性总酸度逐代增大有关。 ( 4 )沙地土壤中脲酶的活性没有明显的变化 ,而磷酸酶、多酚氧化酶和过氧化物酶的活性则随代数的增加而降低。     

南亚热带杉木人工成熟林密度对土壤养分效应研究

[目的]研究5种不同密度林分土壤剖面养分含量的变化规律。[方法]以广西大青山37年生杉木密度试验林为研究对象,测定了A(1 667株·hm-2)、B(3 333株·hm-2)、C(5 000株·hm-2)、D(6 667株·hm-2)、E(10 000株·hm-2)5种密度下0 100 cm土层土壤养分含量。利用单因素方差分析和多重比较判断不同密度和不同土层土壤养分含量的差异。[结果]表明:(1)杉木人工成熟林大多数土层土壤有机质、全氮、碱解氮、全磷、有效性铁含量在A、B等低密度林分中最高,并且在0 30 cm的土壤中,随密度的增加表现出总体下降的变化趋势,而土壤pH值与全钾、速效钾随密度的增加而上升,交换性钙与交换性镁含量受密度影响不明显;(2)土壤有机质、全氮、碱解氮、有效磷、速效钾、交换性钙、交换性镁和有效性铁含量均随土层深度的增加而明显下降,0 30 cm表层土壤的降幅较大,密度对不同土壤深度养分含量的变化具有一定影响。[结论]初植密度对杉木人工成熟林土壤养分含量影响明显,低初植密度更有利于杉木人工林土壤肥力的长期维持,南亚热带杉木林密度对土壤养分的影响深度可达60 cm。     

树木园不同树种人工林土壤养分变化特征

人工造林对土壤养分变化的影响一直是森林培育过程中受到关注的问题之一。采用典型样地取样和室内分析的方法,研究了树木园不同针阔叶树种林地土壤养分含量的变化。结果表明:相同立地条件下,人工造林后土壤养分的表聚性明显,且树种不同对土壤养分含量的影响不同;栽植针叶树种主要是改善浅层土壤全氮含量,并明显提高0～40 cm土层有机质、速效氮、速效磷含量,而对土壤全磷、全钾含量影响不明显,甚至降低了土壤全磷含量;而栽植阔叶树种后,不同土层深度土壤有机质、全氮、速效氮和速效磷含量均高于对照样地,且对改善土壤全氮、速效氮和速效磷含量的效果明显好于针叶树种。内蒙古林科院树木园不同树种林地土壤养分含量明显增加,尤其是增加表层0～5 cm有机质、全氮、速效氮和速效磷含量,而阔叶树种对增加全磷、速效磷含量好于针叶树种。     

红锥人工幼林土壤肥力主要指标时空变化特征

为研究红锥(Castanopsis hystrix)人工林土壤肥力指标的变化规律,对广西南宁老虎岭红锥幼林进行了定位跟踪,并对土壤的p H值、有机质、碱解氮、有效磷、速效钾等指标进行了综合分析。结果表明:红锥幼林同一林龄,除全磷随着土层的加深基本保持不变以及全钾随着土层的增加而升高外,其它土壤肥力主要指标基本表现出随着土层的加深而降低。随着林龄的增加,0~20 cm层土壤水解氮表现了不断降低趋势,0~20 cm层土壤全钾、速效钾、交换性镁、有效锌、有效铁表现出一定的增加趋势。除有效铁外,其它微量元素有效养分各林龄之间均无显著性差异。全钾与有机质、全氮、水解氮、速效钾、交换性钙、交换性镁、有效锌、有效硼、有效铁之间表现了显著负相关,其它各指标之间均表现了无显著相关或显著正相关关系。红锥幼林在地力维持方面表现较佳。     

短周期杉木人工林不同林龄土壤肥力综合评价

为探讨不同生长发育阶段林地土壤肥力状况及地力衰退趋势,分析影响地力衰退的主要影响因子,以不同林龄(2、4、6、8和11 a)杉木短周期小径材培育人工林的土壤样本为研究对象,检测土壤有机质、全氮、全钾、全磷、水解性氮、速效钾、有效磷、有效铁、交换性钙、交换性镁含量和pH值共11个土壤肥力指标,分析不同林龄土壤养分差异及其变化趋势。结果表明:除土壤pH值外,土壤主要肥力指标的变化幅度较大,有机质、全氮、水解性氮、速效钾、有效磷含量在不同土层和不同林龄间均存在极显著差异(P<0.01);随着林龄的增长,林地土壤有机质和氮磷肥消耗较大,其中,表土层(0~20 cm)有机质、水解性氮、有效磷含量到11 a主伐时的降幅均超过30%,但不同林龄间各肥力指标差异不显著;采用改进后的Nemerow法计算的土壤肥力综合指数为0.412~0.530,土壤肥力等级为Ⅲ级(P_综<0.9),土壤肥力较低,相比较而言,土壤中有机质和氮肥含量较充足,而交换性阳离子极为贫乏;有机质、速效钾、水解性氮、有效磷含量与综合肥力指数呈显著或极显著正相关(R_偏~2>0.8),是影响土壤肥力的主要因子;土壤肥力综合指数随林龄增大而降低,11 a主伐期比造林初期(2 a)下降22.26%,但不同林龄间各单项肥力指数及综合肥力指数均不存在显著差异(P>0.08)。在该栽培模式的超短经营周期内,随着林龄增大及林木生长对土壤养分的消耗,林地土壤肥力出现一定程度的退化现象,但并未达到显著水平,有必要通过提高整地质量、改良土壤、林粮间作、增施有机肥及氮磷钾肥等措施适度增加土壤肥力,维持林地长期生产力。     

杉木幼林地喷施草甘膦后土壤的变化

对长泰县岩溪国有林场杉木幼林地喷施草甘膦后土壤变化的初步研究表明 ,喷施地在根系密集区其土壤的物理性质和化学性质都有不同程度的变化。土壤容重值下降 ,而有机质、全氮、碱解氮、速效钾和土壤自然含水率都有不同程度的增加 ,但土壤 pH值微小下降。喷施草甘膦的幼林杉木与用人工除草深翻杉木 ,生长情况相似     

基于Nemerow法和隶属度函数的湖北杉木人工林土壤肥力评价

[目的]对湖北省杉木人工林土壤肥力进行评价,为该区域杉木人工林立地选择、土壤管理及合理经营提供理论依据.[方法]采集保康、谷城、阳新、咸安、通城5个县市31个杉木人工林样点0～100 cm的土壤样本,检测有机质、全氮、全钾、全磷、水解性氮、速效钾、速效磷、有效铁、交换性钙、交换性镁及pH值共11个土壤肥力指标,分别采用...     

祁连山大野口流域典型干性灌木林土壤养分特征

以祁连山大野口流域低海拔分布的甘青锦鸡儿和鲜黄小檗2种典型干性灌木林土壤为研究对象,研究了其0～60 cm土壤有机碳、pH值、碱解氮、速效磷、速效钾、交换性钙、交换性镁等养分剖面含量分布规律,并进行了养分间的相关性分析。研究结果表明:2种灌木林土壤有机碳含量随土层深度增加不断减小,鲜黄小檗灌木林土壤有机碳含量明显大于甘青锦鸡儿灌木林;2种灌木林土壤酸碱性均表现为弱碱性,差异不明显;2种灌木林碱解氮和速效钾含量随土层深度增加其含量不断减小,速效磷在0～30 cm土层表现为增加的趋势,30 cm以下土层变化不明显,交换性钙和交换性镁随土层深度增加没有明显的变化规律,碱解氮、速效磷、速效钾含量表现为鲜黄小檗灌木林明显大于甘青锦鸡儿灌木林,交换性钙和交换性镁含量在2种灌木林中的均值差异性不明显;这些养分之间仅有机碳含量与碱解氮含量之间具有极显著相关性(P0.05),其他因子之间无显著相关性(P0.05)。对祁连山低海拔干性灌木林的经营管理需要加强保护。     

杉木幼林地喷施草甘膦后土壤的变化

对长泰县岩溪国有林场杉木幼林地喷施草甘膦后土壤变化的初步研究表明，喷施地在根系密集区其土壤的物理性质和化学性质都有不同程度的变化。土壤容重值下降，而有机质、全氮、碱解氮、速效钾在土壤自然含水率都有不同程度的增加，但土壤pH值微小下降。喷施草甘膦的幼林杉木与用人工除草深翻杉木，生长情况相似。     

林用除草剂草甘膦的环境行为及生态风险研究进展

林业除草是营林生产过程的重要环节,美国孟山都公司研发的林用除草剂草甘膦以其杀草广谱、内吸传导性强的优势在林业生产中被广泛采用。然而随着草甘膦的过量使用,残留在林地土壤中的草甘膦势必增加,不仅作用于靶生物以防除杂草,而且对非把生物也产生影响,导致林地生态系统结构改变,功能遭受破坏。近年来,虽然国内外学者对草甘膦在农业应用的环境行为和生态风险进行了大量研究,但对于草甘膦在林业上的研究鲜见报道。文中从草甘膦的除草机理、在林地土壤中的环境行为、林用生态风险以及合理使用等方面综述了草甘膦在林业应用中的研究进展,以期为人工林经营过程中草甘膦的合理使用提供科学参考。     

除草剂草甘膦对板栗根际土壤微生物多样性的影响

近年来,除草剂的使用已成为提高作物产量和品质的一种常用手段,伴随而来的是土壤微生物多样性失调及污染严重等生态问题。为了促使板栗能健康生长并保证其果实品质,利用Illumina Miseq高通量技术,分别对草甘膦施用后不同时间采集的根际土壤样品中细菌16S rRNA的V3-V4区和真菌ITS1-ITS2区进行测序,分析微生物群落的组成和多样性的变化情况。多样性分析结果表明:以草甘膦处理6和12d后,板栗根际土壤细菌的多样性和丰富度均无显著变化,真菌多样性显著降低,真菌丰富度先增加后不变。群落结构分析结果表明:板栗根际土壤优势细菌菌门主要是变形菌门、放线菌门、酸杆菌门等,优势真菌菌门主要是子囊菌门和担子菌,随着草甘膦处理时间的增加,变形菌门、子囊菌门的相对丰度均先增加后不变,酸杆菌门的相对丰度先增加后降低,担子菌门的相对丰度先增加后保持不变。研究结果表明:草甘膦对板栗根际土壤微生物多样性及群落组成均产生了一定的影响,其影响随着施药时间的延长而发生变化。     

Effects of stand density on ecosystem properties of subalpine forests in the southern Rocky Mountains, USA

? Mixed coniferous, subalpine forest communities in the Rocky Mountains are historically dense and have experienced infrequent, high-severity fire. However, many of these high-elevation stands are thinned for a number of perceived benefits.

? We explored the effects of forest stand density on ecosystem properties in subalpine forests in Colorado, USA, 17–18 y after forests were managed for timber.

? Forest structure significantly altered the composition and chemical signature of plant communities. Previously managed stands contained lower density of overstory trees and higher ground cover compared to paired reference stands. Foliar phenolic concentration of several species was negatively related to basal area of overstory trees. Furthermore, reductions in stand density increased total foliar phenolic:nitrogen ratios in some species, suggesting that gap formation may drive long-term changes in litter quality. Despite significant changes in forest structure, reductions in stand density did not leave a strong legacy in surface soil properties, likely due to the integrity of soil organic matter reserves.

? Changes in forest structure associated with past management has left a long-term impact on plant communities but has only subtly altered soil nutrient cycling, possibly due to trade offs between litter decomposability and microclimate associated with reductions in canopy cover.

     

Soil physical properties degrade further on skid trails in the year following operations

Short-term recovery of soil physical properties on skid trails was investigated upon cessation of skidding operations and 1 year later. Bulk density and porosity were assessed at three levels of traffic intensity and two slope gradients. Compared to undisturbed areas, bulk density increased, total porosity and macroporosity decreased, and microporosity increased in the compacted areas immediately after skidding. In all cases, changes were significantly greater when traffic intensity was higher and when slopes were steeper. Surface soil compaction did not show any recovery over the 1-year period, illustrating the persistent effects of compaction on soil structure. In fact, surficial compaction further increased and macroporosity further decreased after 1 year of recovery, compared to immediately after skidding. While these changes may reflect inherent small-scale site variability or differences in soil moisture content at times of sampling, direct negative physical impacts on newly exposed soil (such as by raindrops), in addition to the loss of organic matter after canopy removal and skidding, likely delayed any physical recovery, particularly on heavily trafficked trails on steeper slopes. These results raise serious concerns about long-term resilience to traffic on forest soils and indicate the necessity to properly retire skid trails to avoid further soil degradation as trails age.     

Short- and long-term responses of total soil organic carbon to harvesting in a northern hardwood forest

The long-term response of total soil organic carbon pools (‘total SOC’, i.e. soil and dead wood) to different harvesting scenarios in even-aged northern hardwood forest stands was evaluated using two soil carbon models, CENTURY and YASSO, that were calibrated with forest plot empirical data in the Green Mountains of Vermont. Overall, 13 different harvesting scenarios that included four levels of aboveground biomass removal (20%, 40%, 60% and 90%) and four different rotation lengths (60 year, 90 year, 120 year, and No Rotation (NR)) were simulated for a 360 year period. Simulations indicate that following an initial post-harvest increase, total SOC decreases for several decades until carbon inputs into the soil pool from the re-growth are greater than losses due to decomposition. At this point total SOC begins to gradually increase until the next harvest. One consequence of this recovery pattern is that between harvests, the size of the SOC pool in a stand may change from −7 to 18% of the pre-harvest pool, depending on the soil pool considered. Over 360 years, the average annual decrease in total SOC depends on the amount of biomass removed, the rotation length, and the soil pool considered. After 360 years a stand undergoing the 90yr-40% scenario will have 15% less total SOC than a non-harvested stand. Long-term declines in total SOC greater than 10% were observed in the 60yr-60%, 60yr-90%, and 90yr-90% scenarios. Long-term declines less than 5% were observed in scenarios with 120 year rotations that remove 60% or less of the aboveground biomass. The long-term decreases simulated here for common management scenarios in this region would require intensive sampling procedures to be detectable.     

Effects of the vegetation restoration years on soil microbial community composition and biomass in degraded lands in Changting County,China

We evaluated the effects of the number of years of restoration of vegetation on soil microbial community structure and biomass in degraded ecosystems.We investigated the microbial community structure by analyzing their phospholipid fatty acids then examined microbial biomass carbon and nitrogen by chloroform fumigation extraction of restoration soils over several years.The data were compared with those of highly degraded lands and native vegetation sites.The results show that the duration of vegetation on the sites substantially increased microbial biomass and shifted the microbial community structure even after only 4 years.However,microbial communities and biomass did not recover to the status of native vegetation even after 35 years of vegetation cover.A redundancy analysis and Pearson correlation analysis indicated that soil organic carbon,total nitrogen,available potassium,soil water content,silt content and soil hardness explained 98.4% of total variability in the microbial community composition.Soil organic carbon,total nitrogen,available potassium and soil water content were positively correlated with microbial community structure and biomass,whereas,soil hardness and silt content were negatively related to microbial community structure and biomass.This study provides new insights into microbial community structure and biomass that influence organic carbon,nitrogen,phosphorus and potassium accumulation,and clay content in soils at different stages of restoration.     

植被恢复对建筑垃圾填埋场土壤理化性质变化的影响研究

对徐州市九里山建筑垃圾填埋场人工造林恢复植被后的土壤理化性质进行研究的结果表明,恢复样地土壤孔隙度增大,土壤密度减小,土壤pH呈下降趋势,土壤有机质和土壤全氮水平显著增加。但土壤全磷和有效磷含量随植被的生长呈降低趋势,原因可能为当土壤中有效磷含量不能满足植物根系吸收时,植物根系会分泌一些有机酸来活化土壤中的磷元素供植物吸收。土壤全钾含量没有显著差异,速效钾含量随着植被的生长而降低。     

Effects of chronic nitrogen amendment on dissolved organic matter and inorganic nitrogen in soil solution

Increased atmospheric deposition of N to forests is an issue of global concern, with largely undocumented long-term effects on soil solution chemistry. In contrast to bulk soil properties, which are typically slow to respond to a chronic stress, soil solution chemistry may provide an early indication of the long-term changes in soils associated with a chronic stress. At the Harvard Forest, soil solution was collected beneath the forest floor in zero tension lysimeters for 10 years (1993–2002) as part of an N saturation experiment. The experiment was begun in 1988 with 5 or 15 g N m⁻² per year added to hardwood and pine forest plots, and our samples thus characterize the long-term response to N fertilization. Samples were routinely analyzed for inorganic nitrogen, dissolved organic nitrogen (DON), and dissolved organic carbon (DOC); selected samples were also analyzed to determine qualitative changes in the composition of dissolved organic matter. Fluxes of DOC, DON, and inorganic N were calculated based on modeled water loss from the forest floor and observed concentrations in lysimeter samples. The concentration and flux of inorganic N lost from the forest floor in percolating soil solution are strongly affected by N fertilization and have not shown any consistent trends over time. On average, inorganic N fluxes have reached or exceeded the level of fertilizer application in most plots. Concentrations of DOC were unchanged by N fertilization in both the hardwood and pine stands, with long-term seasonal averages ranging from 31–57 mg l⁻¹ (hardwood) and 36–93 mg l⁻¹ (pine). Annual fluxes of DOC ranged from 30–50 g m⁻² per year. DON concentrations more than doubled, resulting in a shift toward N-rich organic matter in soil solution percolating from the plots, and DON fluxes of 1–3 g m⁻² per year. The DOC:DON ratio of soil solution under high N application (10–20) was about half that of controls. The organic chemistry of soil solution undergoes large qualitative changes in response to N addition. With N saturation, there is proportionally more hydrophilic material in the total DON pool, and a lower C:N ratio in the hydrophobic fraction of the total DOM pool. Overall, our data show that fundamental changes in the chemistry of forest floor solution have occurred in response to N fertilization prior to initiation of our sampling. During the decade of this study (years 5–14 of N application) both inorganic N and dissolved organic matter concentrations have changed little despite the significant biotic changes that have accompanied N saturation.     

无公害施肥对茶园土壤理化性质的影响[]

文章研究无公害施肥对粤东乌龙茶茶园土壤自然含水量和土壤容重等物理性质、有机质、全氮、碱解氮等土壤养分的影响,结果表明：铺草、施绿肥、施有机肥均能提高土壤自然含水量和有机质质量比,而施有机肥对提高土壤有机质质量比的效果最好;施绿肥和铺草对于提高土壤全氮和碱解氮质量比的效果不明显,而施有机肥可以明显提高土壤全氮和碱解氮质量比,因此粤东各地茶园可以因地制宜改善本地的茶园土壤,采取施有机肥结合铺草措施,保证土壤肥力供应和含水量。     

Active organic carbon pool of coniferous and broad-leaved forest soils in the mountainous areas of Beijing

In order to explore the effects of different forest types on active soil carbon pool, the amounts and density of soil organic carbon (SOC) were studied at different soil horizons under typical coniferous and broad-leaved forests in the mountainous area of Beijing. The results showed that the amount of total SOC, readily oxidizable carbon and particulate organic carbon decreased with increasing depths of soil horizons and the amounts at depths of 0–10 cm and 10–20 cm in broad-leaved forest was clearly higher than that in coniferous forests. The trend of a decrease in SOC density with increasing depth of the soil horizon was similar to that of the amount of SOC. However, no regular trend was found for SOC density at different depths between coniferous forest and broad-leaved forests. The ratio of readily oxidizable carbon to total amount of SOC ranged from 0.36–0.45 and the ratio of particulate organic carbon to total amount of SOC from 0.28–0.73; the ratios decreased with increasing depths of soil horizons. Active SOC was significantly correlated with total SOC; the relationship between readily oxidizable carbon and particulate organic carbon was significant. A broad-leaved forest may produce more SOC than a coniferous forest.