天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

Seasonal variation in field-saturated hydraulic conductivity in two swelling clay soils in Sweden

A simple method (the inversed auger hole method) for measuring field-saturated hydraulic conductivity (K_fs) was investigated. Measurements were carried out in the spring, summer and autumn at three depths in two Swedish clay soils (Ultuna and Limsta, with clay contents of 45–60%0 and 65–80%, under barley and grass/clover ley respectively). Seasonal fluctuations in K_fs at Limsta were more pronounced, and were observed deeper in the profile. This was attributed primarily to larger structural changes due to a higher capacity for swell/shrink (normal shrinkage over the available water range) and an earlier drying up of the soil under grass/clover ley. It was shown that the measured K_fs values were strongly correlated with the total inter aggregate (macro-) porosity (e_t), estimated from a simple model of soil shrinkage. Combining the data from both soils, a single power-law relation was adequate (r= 0.73) to describe the variations in K_fs with e_t     

Nitrogen dynamics in different types of pasture in the Austrian Alps

 Soil N dynamics were compared in Alpine pastures on two mountains. N-pool sizes and N fluxes were measured relative to N losses via leaching and denitrification in summer. On each mountain, four types of pasture were studied: (1) forest pastures, (2) recently developed pastures formed by forest clearance ("new pastures"), (3) older established pastures, and (4) pastures planted with clover. At both study sites (Scheuchegg and Teufelstein) we obtained similar results. Compared with forest pasture soils, open pasture soils were found to have greater microbial biomass and faster mineralisation potentials, but net field mineralisation rates were slower. In the forest pastures, highest N losses via denitrification were found. Higher potential leaching of NO₃ ^–, estimated by accumulation of NO₃ ^– on ion-exchange resins, in the forest pasture soils suggests lower N uptake by microbes and herbaceous plants compared with open pastures. N₂O-production rates of the forest pasture soils at the Scheuchegg site (11.54 μg N₂O-N m^–2 h^–1) were of similar magnitude to those reported for spruce forests without pastures, but at Teufelstein (53.75 μg N₂O-N m^–2 h^–1) they were higher. However, if forest pastures are not overgrazed, no elevated N loss through N₂O production and leaching of NO₃ ^– is expected. Denitrification rates in the open pastures (0.83–7.50 μg N₂O-N m^–2 h^–1) were low compared with reports on lowland pastures. In soils of the new pastures, rates of microbial N processes were similar to those in the established pastures, indicating a high capacity of soils to restore their internal N cycle after forest clearance. Received: 19 August 1999     

Speciation of copper in soils and relation with its concentration in fruits

Abstract

Different extraction reagents were studied in soils and the results obtained were compared with copper (Cu) contents of seven type fruits grown in these soils. For fruits, wet and dry ashing methods were applied and acceptable results were obtained by using dry ashing. The speciation is based on the dissolution of the soil samples in HNO₃/H₂O₂, oxalic acid, acetic acid, EDTA and citric acid as extraction reagents at hot and cold conditions. Mean total Cu concentrations for all fruits studied were (mg kg^‐1) in the range of 3.0–7.0 (dried weight basis). Significant positive correlations have been found between Cu contents of various fruits and different extractants studied. Flame atomic absorption spectrometry was used for determination of Cu in digestions. Probable chemical forms of Cu in soils were evaluated.     

Variation in Stream Water Quality in an Urban Headwater Stream in the Southern Appalachians

We examined the influence of a forested landscape on the quality of water in a stream originating on an urban landscape and flowing through National Forest lands. Sample sites included an urban stream (URB), a site on the same stream but within a National Forest (FOR) and 2 km downstream from the URB site, and a small, undisturbed, forested reference tributary of the main stream (REF). We monitored stream water quality from March 2002 through June 2003. Average base flows for the three stream sites were URB = 184 L s^?1, FOR = 420 L s^?1, and REF = 17 L s^?1. We analyzed weekly stream water samples for NO₃ ^?, NH₄ ⁺, PO₄ ⁺, Cl^?, K, Ca, Mg, SO₄, SiO₂, pH, conductivity, total suspended solids (TSS), and bacteria on a monthly basis. Most solutes were higher in concentration at the URB site, as were conductivity, TSS, and bacteria counts. Reductions in NO₃ ^?, NH₄ ⁺, and PO₄ ⁺ concentrations between the URB and FOR sites were inferred from changes in nutrient:chloride ratios. Bacteria populations were greater and more responsive to stream temperature at the URB site. Water quality responses to changes in stream discharge varied among sites but were greater at the URB site. By all measures, water quality was consistently higher at the FOR site than at the URB site.     

上海地区池塘养殖生态服务价值的时空差异分析

池塘养殖在中国渔业生产体系中占有重要的位置,它具有食物供给、空气(气温)调节、文化休憩服务等多重生态服务价值,同时也会对环境造成一定的负面影响,即存在环境成本。为进一步厘清池塘养殖生态服务价值的变化规律,本文基于前期研究成果,在构建池塘养殖生态服务价值评估体系的基础上,采用市场价值法(MVM)、旅行成本法(TCM)、条件价值评估法(CVM)、影子工程法(SEM)等方法对上海嘉定、青浦、奉贤地区的池塘养殖生态服务价值进行了系统评估,并分析了池塘养殖生态服务价值的时空分布差异,对因地制宜促进池塘养殖产业的发展提出了建议。结果表明:1)2011年,嘉定、青浦、奉贤3区的池塘养殖生态服务价值分别为0.822 8亿元、8.462 8亿元和15.588 4亿元,相当于各区池塘养殖产业经济价值的2.69倍、1.94倍和2.17倍,约合94.08万元.hm 2、20.00万元.hm 2和32.73万元.hm 2,池塘养殖生态服务价值巨大且时空分布差异明显;2)嘉定、青浦、奉贤未实现的池塘养殖生态服务价值是各区池塘养殖食物供给净价值的5.46倍、1.23倍、0.46倍,具有巨大的潜在生态经济效益;3)受养殖经济效率时间变化的影响,2010—2011年研究区常规鱼类养殖规模大幅减少,青虾、南美白对虾逐渐成为主要的养殖品种;4)池塘养殖生态服务价值时间分布集中且波动明显,大部分服务价值集中于第3季度,其中文化休憩服务价值主要集中于4—9月,空气调节价值主要集中于7—12月,而气温调控价值集中于5—9月;5)养殖规模对生态服务价值的时空分布具有重要影响,池塘养殖生态服务价值整体服从规模效应,但不同类型的生态服务价值的时间分布规律并不统一。养殖经营者应积极调整池塘养殖经营战略,大力发展休闲渔业,提高池塘生态服务价值的实现化程度,政府需要制定并执行必要的生态补偿政策。     

Potential N mineralization and availability to maize in black soils in response to soil fertility improvement in Northeast China

Purpose

Understanding the soil nitrogen (N) mineralization potential (N₀) and crop N availability during the growing season is essential for improving nitrogen use efficiency (NUE) and preventing over-fertilization, which lead to negative environmental impacts.

Methods

Five black soils with different levels of fertility were selected in Northeast China. The N₀ and kinetics of these soils were estimated through laboratory experiments at different incubation temperatures (15, 25, and 35 °C). N mineralization dynamics were simulated using field soil temperature according to the incubation results. Moreover, the N uptake dynamics of maize were simulated according to the literature.

Results

Compared with the very low-fertility soils, the cumulative mineralized nitrogen increased under all incubation temperatures (15, 25, and 35 °C), by 48–136%, 8–61%, and 24–59%, respectively, in the medium- and high-fertility soils. The highest N₀ values (96.90, 115.31, and 121.33 mg/kg at the three different temperatures) were recorded in the very high-fertility soils. The soil N mineralization dynamics and N uptake of maize in the growing season were highly consistent over time, although the soil N supply could not meet the maize growth requirements. The higher the soil fertility, the lower the N fertilizer requirement.

Conclusions

Different fertilizer strategies were developed based on the cumulative mineralized N, N uptake by maize, and NUE in soils with different fertility levels. We suggested a reduction of 50–65 kg N/ha in N fertilizer in the two highest fertility soils. This study provided basic data to reduce chemical N fertilizer to improve NUE and reduce negative environmental impacts.

     

龙游硫铁矿区农田土壤重金属污染的空间 变异及在水稻中的积累

为了解浙江龙游硫铁矿区农田重金属污染状况,采集矿区265件农田土壤样品,分析8种重金属Cu、As、Hg、Zn、Cd、Ni、Pb、Cr元素全量,利用地统计学软件GS+9.0对研究区土壤各元素指标进行半变异函数拟合,并利用普通克里格法进行插值并绘制空间分布图。采集30件水稻籽粒样品,分析重金属在研究区中水稻籽粒的累积特征,并进行了健康风险评价。结果表明:矿区土壤中8种重金属元素的变异系数从0.72到1.76,离散程度较高。8种重金属的土壤空间半变异函数Cu、As、Hg元素符合指数模型,Zn、Cd、Ni、Pb符合球状模型,Cr符合高斯模型。元素Cu、Pb、Zn、Cr、Ni的块金值与基台值的比值C0/C0+C都小于0.25,说明空间变化主要受地质背景等因素影响;元素Cd、Hg和As的块金值与基台值的比值C0/C0+C在0.25~0.75之间,说明除了地质背景因素,人为活动等随机因素也有影响。矿区水稻籽粒中重金属Ni和Cd的变异系数最高,分别为0.95和0.87,说明Ni和Cd元素可能存在异常积累。矿区水稻籽粒对重金属的富集能力由大到小依次为Cd、Zn、Cu、Ni、As、Hg、Cr、Pb。健康风险评价结果表明矿区农田水稻籽粒中元素As、Cd的风险商大于1,存在潜在健康风险;而其他6种重金属Cu、Hg、Zn、Ni、Pb和Cr基本属于安全范围。     

Nitrogen use in maize-grain legume cropping systems in semi-arid Kenya

Locally suitable cultivars of maize, beans, and cowpeas were grown in field experiments for four seasons in semi-arid Kenya. For three seasons, the dry matter production and grain yield of maize and beans were not increased by N fertilizer additions up to 120 kg N ha^-1. Fertilizer recoveries measured by ¹⁵N isotope dilution techniques were low, less than 20%. Inoculated and uninoculated beans failed to fix N₂. By contrast the cowpea derived 50% of its N from fixation, equivalent to 197 kg N ha^-1. The N content of the grain generally exceeded 40 kg N ha^-1, and the N content of the seeds from the grain legumes were greater than those from the cereals. Large inputs of N fertilizer or N by fixation are required if maize-grain legume cropping system in semiarid Kenya are to be sustained in the long term.     

Eucalyptus camaldulensis and Pinus caribaea growth in relation to soil physico-chemical properties in plantation forests in Northern Nigeria

Abstract

The present study described the relationship between growth and soil physico-chemical properties in Eucalyptus camaldulensis (Myrtaceae) and Pinus caribaea (Pinaceae), two important species in Nigerian forest recovery programs. The study sites were located in a 17-year-old plantation in a Northern Nigeria forest reserve. The soils at the study sites were nutrient poor compared with other plantations. Growth of E. camaldulensis was positively correlated with exchangeable K content in soils 0–20 cm deep, and negatively correlated with total N and exchangeable Na in soils 20–150 cm deep. Growth of P. caribaea was positively correlated with available P in soils 0–20 cm deep, and volumetric water content in soils 20–150 cm deep. Soils in the top layers were very hard and plinthite layers were well developed at shallow soil depths at most sites. E. camaldulensis exhibited a comparatively high survival rate, and its growth was comparable to that in other plantations. However, the survival rates of P. caribaea were low and its growth was lower than that in other plantations. The survival rate of E. camaldulensis was lower at sites where plinthite layers were found within 50.8 cm of the surface. These results indicated that E. camaldulensis is suitable for afforestation in Northern Nigeria. However, it is not recommended for sites where the plinthite layer occurs at shallow soil depths.     

2013年我国种植业化肥施用状况分析

【目的】我国农用化肥消费量大,数据来源不同,统计口径各异,行业内大多引用国家统计局公布的数据,但该数据无法推算出氮肥、磷肥、钾肥分类消费量。我国区域间、季节间、作物间化肥消费情况的报道很少,在调节化肥供需、指导化肥行业健康发展时显得依据不足。调查种植业化肥施用状况可以为指导肥料生产、供应提供重要依据。【方法】以农业部339个国家级基层肥料信息网点为依托,根据我国农业生产习惯和我国政府部门统计习惯,将一年分为三个用肥季,1 5月份为春耕季,6 8月份为夏播季,9 12月份为秋冬种季。在三个季节,每个网点随机调查30个农户的主要种植作物施用氮肥、磷肥、钾肥、复合(混)肥(包括配合式)量,经两级土壤肥料部门审核后,采用省份、相似种植区域、全国三级逐级加权平均的方法,推算了不同区域、不同季节、不同作物单位面积施肥量;再用作物单位面积施肥量、该作物全国种植总面积、样本中施肥面积占该作物种植面积的比例推算了作物全年、不同季节化肥施用量。同时,分析了主要作物、不同季节化肥施用状况以及供需平衡情况,不同季节、不同区域供肥情况和农民的购肥习惯。【结果】2013年我国种植业化肥施用量5498万吨(折纯下同),其中,氮肥(实物量)3382万吨,磷肥1175万吨,钾肥941万吨。粮食作物化肥总用量为2782万吨,占种植业化肥总用量的50.6%;其次是果树和蔬菜,三类作物占种植业化肥施用总量的82.8%,经济、园艺作物单位面积化肥施用量大于粮食作物。春耕、夏播、秋冬种化肥施用量分别占全年化肥施用量的34.2%、35.6%、30.2%。复混肥料和尿素是农民最常购买的两种肥料,从全年来看,农民施用复混肥料和尿素的样本数分别占总样本数的72.5%和71.6%,春耕、夏播、秋冬种农民购买尿素和复合(混)肥的样本数分别占该阶段样本数的70.9%和62.9%、84.9%和78.1%、56.6%和83.9%。春耕和夏播时期农民多数选用尿素,秋冬种多数选用复混肥料,东北、西北、华中南地区农民多选用尿素,华北、西南、华东地区农民多选用复混肥料。另外,我国氮肥、磷肥供应分别过剩1080万吨、680万吨,钾肥缺口370万吨,供需矛盾突出。氮、磷、钾养分配合式为15-15-15的复混肥样本数占农民选购复混肥总样本数的33.3%,说明复混肥养分结构不尽合理。【结论】建议国家进一步遏制氮肥、磷肥过剩产能,优化产品结构,大力推广科学施肥技术。     

Changes in nematode abundances and body length in response to management intensive grazing in a low-input temperate pasture

An evaluation of changes in nematode populations in response to management was performed using a field scale experiment along a gradient of land-use intensity in the context of management intensive grazing. Four levels of decreasing intensity were measured over three growing seasons. The treatments included: 1) intensive grazing management where cows were allowed to graze for each grazing cycle, followed by routine clipping and harrowing; 2) semi-intensive grazing where cows were allowed to graze for each grazing cycle, with only one clipping event per year; 3) extensive grazing where cows were allowed to graze during every 2nd grazing cycle and no clipping or harrowing was performed; 4) stockpiling treatment where cows were permitted to graze only during the final grazing cycle, followed by clipping at the end of the season. Most indices (MI, PPI, ∑MI, and ∑MI25) resulted in significant seasonal differences; however, only familial diversity (H′) and the total number of families showed significant season by treatment interaction. Bacterivores comprised most of the nematode population with Cephalobidae being the most common family. Abundance of plant feeders was affected by season and soil moisture, whereas bacterivore abundance was associated with total organic N and soil pH. Nematode body length increased slightly in most families through time, and was associated with season, bulk density, soil moisture, and total N and C. Although omnivore numbers were highest in the extensive and semi-intensive treatments, there was a significant increase in dorylaimid body length observed in the intensive treatment through time. Increases in body length were also observed in Monhysteridae and Cephalobidae in all treatments.     

Aluminum toxicity in plants grown in solution culture

Abstract

Earlirose rice (Oryza sativa L. ) and Hawkeye soybeans (Glycine max L.) were grown in solution culture with A1₂(SO₄)₃ in concentrations of 0, 10^‐6, 10^‐5, 10^‐4, 10^‐3 M. Only at 10^‐4 (slightly) and at 10^‐3 M were there yield depressions due to Al. The threshold concentration of Al for toxicity was about 20 μg/g in rice shoots and about 30 μg/g in soybean leaves. The solution level necessary for these concentrations was 8 μg Al/ml. Plant concentrations which caused severe toxicity were 70 μg Al/g plant with 81 μg Al/ml solution. Most Al remained in roots, but leaves contained more than did stems of soybeans. The high Al decreased Fe, Cu, and Mn concentrations in shoots of rice and decreased Fe, Cu, and Zn in roots of rice. The high Al resulted in decreased Fe and Zn in leaves of soybeans. No Fe deficiency symptoms were present due to the high Al.     

喀斯特与非喀斯特地区参考作物蒸散量时空变化分析——以广西壮族自治区为例

参考作物蒸散量(ET_0)是确定植被生态系统需水量的关键因子,其时空分布特征及主要影响因素分析对于制定植被恢复策略与区域水资源配置方案具有重要意义。本文基于FAO-56 Penman-Monteith公式和广西地区25个气象站点1960—2010年的逐日资料,计算了各站点的ET_0,在此基础上采用GIS的克里金插值、Spearman秩次相关法和通径分析方法分析了广西喀斯特与非喀斯特地区ET_0的时空变化特征及其影响因子。结果表明,51年来广西各站点多年平均ET_0为1 138 mm×a~(-1);空间分布呈由南向北、由低纬度向高纬度递减的特征,高值区主要分布在非喀斯特地区,低值区主要分布在喀斯特地区。喀斯特与非喀斯特地区年ET_0累积距平曲线均呈"N"型分布;20世纪70年代最高,90年代最低,21世纪以来年ET_0有所回升,但仍低于51年平均值。此外,喀斯特地区ET_0年际变化小于非喀斯特地区。日照时数、风速和平均温度是影响非喀斯特地区年ET_0变化的主要气象因子,而相对湿度则通过与其他气象因子的相互作用间接对喀斯特地区年ET_0的变化产生较大影响。在季节尺度上,日照时数和平均气温在各季节都是ET_0最主要的影响因子,与ET_0呈正相关关系;风速在喀斯特地区冬、春两季对ET_0的间接作用系数为负,在非喀斯特地区并未发现这一现象。了解不同地区ET_0的变化趋势是植被生态需水定额计算的必要措施。     

Characterization of Elemental Species in PM2.5 Samples Collected in Four Cities of Northeast China

A monitoring program of particulate matter was conducted at eight sampling sites in four highly industrialized cities (Shenyang, Anshan, Fushun, and Jinzhou) of Liaoning Province in Northeast China to identify the major potential sources of ambient PM_2.5. A total of 814 PM_2.5 and PM_2.5–10 samples were collected between 2004 and 2005. All PM samples were collected simultaneously in four cities and analyzed gravimetrically for mass concentrations. A sum of 16 elemental species concentrations in the PM samples were determined using inductively coupled plasma atomic emission spectroscopy. Annual means of PM_2.5 concentrations ranged from 65.0 to 222.0 μg m^?3 in all the eight sampling sites, and the spatial and seasonal variations were discussed. Enrichment factors were calculated, and Cr, Cu, Zn, As, Cd, and Pb will be pollution-derived elements. Site-to-site comparisons of PM_2.5 species in each city were examined using coefficient of divergence, revealing that the two sites in each city are similar in elemental species. Principle component analysis was used for preliminary source analysis of PM_2.5. Three or four factors in each city were isolated, and similar sources (crustal source, coal combustion, vehicle exhaust, iron making, or some other metallurgical activities) were identified at four cities.     

上海市绿地表层土壤有机碳储量的估算

本文调查了上海市472个绿地土壤样点,通过对其土壤有机碳含量、密度等指标进行测定分析,最终估算出上海市绿地土壤表层有机碳储量,同时为预测上海市未来十几年的碳库变化提供数据支撑。研究结果表明:①上海市绿地表层(0～20 cm)土壤有机碳空间分异性较大,土壤有机碳含量和密度表现为西高东低,且自中心向四周逐渐增高。②不同绿地类型土壤有机碳含量大小依次为:公园绿地公共绿地道路绿地;有机碳密度的大小依次为:公共绿地公园绿地道路绿地。不同绿地类型土壤有机碳含量和密度差异显著,其中,城区不同绿地类型土壤有机碳含量和密度差异显著(P0.05),但郊区不同绿地类型土壤有机碳含量和密度差异不显著(P0.05)。③2015年上海市绿地表层土壤有机碳储量约为4.26×106 t。预计到2035年,上海市绿地表层土壤有机碳储量约可达到1.53×107 t。     

Microfungal community structure in anthropogenic birch stands in central Finland

We describe the soil microfungal communities in 30-year-old birch (Betula pendula Roth) stands planted either on former spruce forest soil (BS) or on former arable soil (BF) and compare these with the soil microfungal communities in spruce forests (S), arable fields (F) and old deciduous forests (D). Fungi were isolated from 0- to 3-cm and 3- to 6-cm samples collected in September 1997 and May 1998. Principal components analysis differentiated fungal communities in the S and BS sites from those in the other site types. The Morisita-Horn index of similarity indicated that fungal communities in the F and BF sites were less similar to those in the other site types. Fungal communities of the BS and S sites were more similar in the 3- to 6-cm layer than in the 0- to 3-cm layer, suggesting that it takes >30 years to replace the spruce litter and associated fungal community. Similarity between fungal communities in the F and BF sites was low, indicating significant changes in the fungal community composition following afforestation of field soil by birch. Fungal communities in the BS and BF sites were more similar to each other than those of their original site types. Fungal communities of the BS, BF and S sites were more similar to those of the D sites than those of the F sites were to the D sites. Differences between the fungal communities of the different site types were attributed primarily to litter quality, earthworm community, and secondarily to organic matter, pH, KCl-extractable NH₄⁺, and PO₄^3-.     

Total petroleum hydrocarbons and heavy metals in road-deposited sediments in Tijuana,Mexico

Purpose

A study was carried out to evaluate the concentration of heavy metals (Pb, Cu, Cr, Cd, and Hg) and total petroleum hydrocarbons (TPH) in road-deposited sediments (RDS) from Tijuana, Mexico, and identify their possible sources.

Materials and methods

Thirty RDS samples were randomly collected during the dry season using a brush and dustpan and classified according to construction material, traffic intensity, and land use. Soil samples were collected from a nonurban area and their concentrations were used as background values. For TPH, the samples were quantified gravimetrically after Soxhlet extraction, whereas heavy metals were extracted by acid digestion and their concentrations were measured by atomic absorption spectrometry.

Results and discussion

The mean TPH concentrations for RDS were 4208 mg kg^?1 and ranged from 1186 to 9982 mg kg^?1. For heavy metals, mean concentrations were 31.8, 50.2, 17.1, 0.1, and 0.1 mg kg^?1 for Pb, Cu, Cr, Cd, and Hg, respectively. The Igeo results showed that RDS from Tijuana are moderately to strongly polluted with Pb and Cu and moderately polluted with Cr. Principal component analysis (PCA) showed that Pb, Cu, and Cr could have their origin in tire wear, brake pads, bearings, and bushings.

Conclusions

The findings of this study revealed that RDS from Tijuana are polluted with TPH and heavy metals and that their principal sources are anthropogenic activities.

     

Soil macroarthropod communities in planted birch stands in comparison with natural forests in central Finland

The aim of the study was to compare the soil macroarthropod communities in anthropogenous birch stands of different origin with each other and with natural forests at the same latitude in Finland. A total of nine forest sites was investigated: three birch stands (Betula pendula) planted ca. 30 years prior to the study after clear-cutting of spruce stands (“Birch after Spruce”, BS), three birch stands planted ca. 30 years earlier on arable soil that had been under normal cultivation until reforestation (“Birch after Field”, BF), and three “Natural Deciduous” (D) forests. These were sampled three times in 1998, animals were extracted with large Tullgren funnels, counted per square metre, and their biomasses were weighed or estimated. Several groups were identified to species. Non-Metric Multidimensional Scaling (NMS) was used to analyse the communities of Coleoptera and Arachnida. The macroarthropod communities and biomasses were relatively similar in all study sites. Coleoptera especially did not differentiate much between different kinds of deciduous stands, while there were more differences in Arachnida. The spider communities were fairly similar to those of coniferous forests, while in Coleoptera some of the most abundant species are rare in spruce forests. All dominant species in the study sites are common members of the forest floor fauna, and differ from those of open terrain. The populations in “Birch after Field” were generally low, and their communities could be characterised as impoverished forest communities. There were considerable differences between replicates of the same kind of forest, e.g. the spider community of one deciduous site was similar to one “Birch after Field” site, while two others resembled more the “Birch after Spruce” sites. There was not much indication of increasing numbers and diversity of litter-feeding macroarthropods such as Diplopoda and Isopoda after reforestation with birch. The factors to explain the differences in community composition between different forests are discussed.     

华中黄棕壤和黄褐土粘粒胶膜的微量元素地球化学特征

The relationships between the basic properties and trace elementsin soil argillans and corresponding matrix soils were studied by sampling from the B horizons of 26 Alfisols in croplands of the subtropical area in Central China. The soil elements (K, Na, Ca, Mg, Mn, Co, Cu, Cr, Cd, Li, Mo, Ni, Pb, Ti, V, and Zn) were extracted by acid digestion and their contents were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean contents of clay and organic matter in the argillans were approximately 1.1 and 1.3 times greater than those in the matrix soils, respectively. The pH values and the contents of P₂O₅ and bases (K₂O, Na₂O, CaO, and MgO) in the argillans were higher than those in the corresponding matrix soils. Cu, Cd, Ti, and V were enriched in the argillans. Correlation coefficients and factor analyses showed that Co, Cu, Li, and Zn were bound with phyllosilicates and manganese oxides (Mn-oxides) in the argillans. Cr and Pb were mainly associated with iron oxides (Fe-oxides), while Ni was bound with Mn-oxides. Cd, Ti, and V were chiefly associated with phyllosilicates, but Cr and Mo were rarely enriched in the argillans. In contrast, in the matrix soils, Co and Zn were associated with organic matter and Fe-oxides, Cr existed in phyllosilicates, and Mo was bound to Fe-oxides. Cd, Ti, and V were associated with organic matter. The results of this study suggest that clays, organic matter, and minerals in the argillans dominate the illuviation of trace elements in Alfisols. Argillans might be the active interfaces of elemental exchange and nutrient supply in cropland soils in Central China.