Growth rates of Aporrectodea caliginosa (Oligochaetae: Lumbricidae) as influenced by soil temperature and moisture in disturbed and undisturbed soil columns

Earthworm growth is affected by fluctuations in soil temperature and moisture and hence, may be used as an indicator of earthworm activity under field conditions. There is no standard methodology for measuring earthworm growth and results obtained in the laboratory with a variety of food sources, soil quantities and container shapes cannot easily be compared or used to estimate earthworm growth in the field. The objective of this experiment was to determine growth rates of the endogeic earthworm Aporrectodea caliginosa (Savigny) over a range of temperatures (5–20 °C) and soil water potentials (−5 to−54 kPa) in disturbed and undisturbed soil columns in the laboratory. We used PVC cores (6 cm diameter, 15 cm height) containing undisturbed and disturbed soil, and 1 l cylindrical pots (11 cm diameter, 14 cm height) with disturbed soil. All containers contained about 500 g of moist soil. The growth rates of juvenile A. caliginosa were determined after 14–28 days. The instantaneous growth rate (IGR) was affected significantly by soil moisture, temperature, and the temperature×moisture interaction, ranging from −0.092 to 0.037 d⁻¹. Optimum growth conditions for A. caliginosa were at 20 °C and −5 kPa water potential, and they lost weight when the soil water potential was −54 kPa for all temperatures and also when the temperature was 5 °C for all water potentials. Growth rates were significantly greater in pots than in cores, but the growth rates of earthworms in cores with undisturbed or disturbed soil did not differ significantly. The feeding and burrowing habits of earthworms should be considered when choosing the container for growth experiments in order to improve our ability to extrapolate earthworm growth rates from the laboratory to the field.     

矿粮复合区煤累积对土壤团粒结构的影响

为理解煤对土壤结构的影响,以土壤煤累积现象普遍的焦作矿粮复合区为研究区,选取3种不同程度的煤累积土壤(低累积、中累积和高累积)为研究对象,不含煤的土壤为对照,通过测定0—40 cm土层深度范围的水稳性团聚体组成,并采用分形维数(D)、平均重量直径(MWD)、几何平均直径(GMD)和大团聚体破坏率(PAD)作为团粒结构的评价指标,探讨煤累积对土壤团聚体组成与稳定性的影响。结果表明:煤在土壤中累积可以促进水稳性微团聚体向大团聚体转化,降低团聚体的分形维数,提高团聚体稳定性。深层(20—40 cm)土壤水稳性大团聚体含量的增幅高于表层(0—20 cm)土壤。土壤团聚体稳定性随着煤累积程度的增高表现出先增加后降低的趋势。土壤团聚体的稳定性主要取决于>2 mm粒级水稳性团聚体的含量。总体上,煤在土壤中的累积改善了土壤的团粒结构性状。此外,根据本研究结果,研究区长期运煤、堆煤、洗煤和矿井水灌排等活动导致的"黑土"现象并不能视作煤污染。     

Soil structure and earthworm activity in a marine silt loam under pasture versus arable land

Agricultural management influences soil organic matter (SOM) and earthworm activity which interact with soil structure. We aimed to describe the change in earthworm activity and related soil (micro)structure and SOM in a loamy Eutrodept as affected by permanent pasture (PP) and conventional arable (CA). Thin sections were studied and biogenic calcite spheroids, worm casts, infillings and groundmass coatings were quantified. In both soils, sedimentary stratification was absent up till 50 cm depth, and equal amounts of biogenic calcite spheroids were counted, suggesting similar earthworm activity in the past. Currently the percentage volume of optically recognizable biologically influenced groundmass was 54% in PP and 10% in CA. The Ah of PP had an organic matter content of 66 mg kg^-1 whereas the content was 22 mg kg^-1 in the Ah of the CA soil. Low earthworm activity in the CA soil has led to the formation of a physicogenetic soil structure with mainly angular blocky aggregates, fissure and angular blocky microstructures. The percentage volume of unsorted coatings counted in thin sections was 5%, indicating soil structure deterioration. SOM was evenly distributed through the groundmass. In contrast, high earthworm activity in the PP soil has caused a biogenic structure consisting of granular and subangular blocky aggregates and spongy and granular microstructures with abundant channels. SOM was incorporated as fine (10-100 µm) particulate organic matter in worm casts and infillings and intimately mixed with clay material. Such encapsulated SOM indicates the presence of microaggregates within biogenic macroaggregates, in which SOM may be physically protected against rapid decomposition.     

Microbial activity and nutrient dynamics in earthworm casts (Lumbricidae)

Summary Microbial respiration, microbial biomass and nutrient requirements of the microflora (C, N, P) were studied in the food substrate (soil taken from the upper 3 cm of the mineral soil of a beech wood on limestone), the burrow walls and the casts of the earthworm Aporrectodea caliginosa (Savigny). The passage of the soil through the gut caused an increase in soil microbial respiration of about 90% over a 4-week period. Microbial biomass was increased only in freshly deposited casts and decreased in aging faeces to a level about 10% lower than in soil. Microbial respiration of the burrow walls was only increased over a shorter period (about 2 weeks). The microflora of the soil and the burrow walls was limited by P, whereas in earthworm casts, microbial growth was limited by the amount of available C. In aging faeces the P requirement of the microflora increased and approached that of the soil. Immobilization of phosphate in earthworm casts is probably caused by mainly abiotic processes. C mineralization by soil microflora fertilized with glucose and P was limited by N, except in freshly deposited casts. Ammonium, not nitrate, was responsible for this process. N dynamics in earthworm casts are discussed.     

Earthworm burrowing in laboratory microcosms as influenced by soil temperature and moisture

Earthworm burrows contribute to soil macroporosity and support diverse microbial communities. It is not well known how fluctuations in soil temperature and moisture affect the burrowing activities of earthworms. The objective of this experiment was to evaluate the maximum depth and length of burrows created by the endogeic earthworm Aporrectodea caliginosa (Savigny) and the anecic earthworm Lumbricus terrestris L. for a range of temperatures (5–20 °C) and soil water potentials (−5 and −11 kPa). The laboratory microcosm was a plexiglass chamber (45 cm high, 45 cm wide) containing 0.14 m² of pre-moistened soil and litter, designed to house a single earthworm for 7 days. Earthworm mass, surface casting and burrowing activities were affected significantly by soil temperature, moisture and the temperature×moisture interaction. Burrow length and maximum burrow depth increased with increasing temperature, but there was less burrowing in wetter soil (−5 kPa) than drier soil (−11 kPa). Weight gain and surface casting, however, were greater in soil at −5 kPa than −11 kPa. Our results suggest more intensive feeding and limited burrowing in wetter soil than drier soil. Earthworms inhabiting the non-compacted, drier soil may have pushed aside particles without ingesting them to create burrows. The result was that earthworms explored a larger volume of soil, deeper in the chamber, when the soil was drier. How these burrowing activities may affect the community structure and activity of soil microorganisms and microfauna in the drilosphere remains to be determined.     

夏尔希里自然保护区典型植被土壤水源涵养功能探究

为了探究夏尔希里自然保护区不同植被类型土壤水源涵养功能特征,在保护区内选取具有代表性的草地、灌木、森林样地共13个,以不同植被类型的土壤为试验材料,采用野外调查与室内试验相结合的方法,分别对保护区内的草地区、灌木区、森林区的土壤水源涵养能力进行定量分析。结果表明:(1)随着土层深度的增加,研究区草地土壤容重逐渐增大,在土壤层0-10 cm处出现最小值为0.69 g/cm^3。草地土壤持水能力和蓄水能力变化规律一致,均表现为0-10 cm>10-20 cm>20-30 cm。(2)随着土层深度的增加,灌木土壤容重变化差异较大,变化范围为0.98~1.63 g/cm^3,最小值出现在土壤层0-10 cm处。各水源涵养能力指标含量在不同的土层深度上差异性显著(P<0.05),灌木持水能力大体表现为0-10 cm>10-20 cm>20-30 cm>30-40 cm>40-50 cm,蓄水能力随着土层深度的增加,呈现先增加后减小的趋势。(3)森林土壤水文物理性质和土壤水源涵养指标之间存在显著性差异(P<0.05),随着土层深度的增加,土壤容重逐渐增大,在土层0-10 cm处出现最小值为0.45 g/cm^3。森林土壤持水能力主要以0-10,20-30,40-50 cm为主,占总持水量的71.6%,蓄水量在水源涵养功能中占比较小。     

Fluorine contamination of soils and earthworms (Lumbricus spp.) near a site of long-term industrial emission in southern Germany

Summary The F contamination of soils and Lumbricus spp. around a site of long-term industrial emission in southern Germany was examined. Among total, water extractable, and HCl-soluble fractions, the latter most appropriately characterized anthropogenic F accumulation. Based on the HCl-soluble fractions from 88 sampling sites, a contamination map consisting of three zones was established. F accumulation in the calcareous soils of the area was restricted to the top 40–50 cm and can be explained by precipitation as CaF₂. Earthworms (Lumbricus spp.) collected from the different zones reflected the F contamination well in the significant correlations found between total F in earthworms with and without gut and the corresponding soils. The bioaccumulation of F in earthworms is obvious, and may become hazardous for the earthworms themselves and for other animals feeding on contaminated soil and/or its fauna. A significantly higher F value was recorded in the linings of earthworm tubes than in the corresponding soil. F translocation by earthworm burrowing may be a mechanism of subsoil contamination.     

Earthworm community development in soils of a reclaimed steelworks

Long-term studies are essential to learn earthworm community development and soil formation post reclamation. Investigations were undertaken at a former steelworks site at Hallside, near Glasgow, UK, reclaimed in the 1990s using a mixture of colliery spoil and sewage sludge. The site was largely planted for production of short rotation coppice willow (Salix spp.). Earthworm inoculation formed a part of the restoration process. Minimal monitoring occurred in the interim, but some records of earthworm sampling existed in 2000 and 2005. This study focused on monitoring earthworms and soil properties across the site, drawing comparisons with adjacent unspoiled soil. Results showed that after 22 years, a species-rich community of earthworms (n=16) colonized the site, with endogeic Aporrectodea caliginosa being dominant by number and anecic A. longa by mass. Across the site, earthworm community density and biomass were 208 individuals m^-2 and 71 g m^-2, respectively. The Shannon diversity index for earthworms was 1.89, with an evenness of 0.68. The sewage sludge increased the soil organic matter, but the stone content of the colliery spoil prevented digging in some locations. Soil chemistry had no negative effect on earthworms, but the compacted substrate did hinder water infiltration. Earthworms colonized the reclaimed site from adjacent areas, and community structure and density below well-drained, scrub-free willow, birch, and grassland were not significantly different (P>0.05) from those of the adjacent unspoiled areas. The results show that the historical earthworm inoculation was unnecessary and badly timed. Future reclamations of similar sites can learn from this investigation.     

不同土地利用方式下的蚯蚓种群特征及其与土壤生物肥力的关系

采用样方法对华北平原(河北曲周)盐渍化改造区7种土地利用方式下的蚯蚓种群进行详细调查,并通过培养实验研究了蚯蚓种群特征对若干土壤生物学指标的影响。结果表明:(1)在7种土地利用调查样地中共存在蚯蚓有3个科,5个属,5个种,其中赤子爱胜蚓(Eisenia fetida)占调查样地总个体数的60%以上,梯形流蚓(Aporrectodea trapezoides)和赤子爱胜蚓两个种在本地区广泛分布,样点出现频率分别为74%和44%,为该地区的优势种;(2)不同土地利用方式的蚯蚓种群密度及生物量变化趋势是:庭院菜地>直立免耕>清茬免耕>商品菜地>传统玉米地>果园>原貌地。其中庭院菜地蚯蚓种群的平均密度和生物量分别达到272 Ind.m-2和68.04gm-2;(3)蚯蚓种群密度和物种数等种群特征与土壤基础呼吸强度、微生物生物量碳含量成显著正相关(p<0.01),与土壤基础呼吸商成显著负相关(p<0.01);(4)不同土地利用方式下,蚯蚓的种群密度、生物量等种群特征对土壤中微生物群落的影响作用显著。蚯蚓生物量越大、种群越丰富的土壤有机质、氮、磷、钾等有效成分越高,反之则相反。室内培养实验表明,随着蚯蚓个体数量增加土壤原生动物总丰度、微生物生物量碳、氮也存在升高的趋势,与用土壤生物学特性指标及土壤化学特性指标评价的结果基本一致。     

Mixing of different mineral soil layers by endogeic earthworms affects carbon and nitrogen mineralization

The effect of the endogeic earthworm species Octolasion tyrtaeum (Savigny) on decomposition of uniformly ¹⁴C-labelled lignin (lignocellulose) was studied in microcosms with upper mineral soil (Ah-horizon) from two forests on limestone, representing different stages of succession, a beech- and an ash-tree-dominated forest. Microcosms with and without lower mineral soil (Bw-horizon) were set-up; one O. tyrtaeum was added to half of them. It was hypothesised that endogeic earthworms stabilise lignin and the organic matter of the upper mineral soil by mixing with lower mineral soil of low C content. Cumulative C mineralization was increased by earthworms and by the addition of lower mineral soil. Effects of the lower mineral soil were more pronounced in the beech than in the ash forest. Cumulative mineralization of lignin was strongly increased by earthworms, but only in the beech soil (+24.6%). Earthworms predominantly colonized the upper mineral soil; mixing of the upper and lower mineral soils was low. The presence of lower mineral soil did not reduce the rates of decomposition of organic matter and lignin; however, the earthworm-mediated increase in mineralization was less pronounced in treatments with (+8.6%) than in those without (+14.1%) lower mineral soil. These results indicate that the mixing of organic matter with C-unsaturated lower mineral soil by endogeic earthworms reduced microbial decomposition of organic matter in earthworm casts.     

庐山杉木林与黄山松林的土壤层水源涵养能力和土壤侵蚀敏感性探究

森林的水土保持效益包含水源涵养能力和土壤的侵蚀敏感性,为探讨基于坡面尺度林分因子对水土流失的影响,进一步揭示森林植被的水土保持效益机制,采用环刀法、EPIC模型等分别计算黄山松林、杉木林的水源涵养能力和土壤侵蚀因子.结果表明:(1)黄山松林的土壤容重在垂直剖面无明显差异,变化范围为0.66～1.10 g/cm3;杉木林...     

Soil structure changes induced by the tropical earthworm Pontoscolex corethrurus and organic inputs in a Peruvian ultisol

Inoculation of Pontoscolex corethrurus (Glossoscolecidae, Oligochaeta) in a Peruvian ultisol under several treatments (without or with organic input) has been previously shown to increase macroaggregation and bulk density and to decrease water infiltration and soil moisture. In the present study, we used image analysis of thin sections of soil to understand the impact of earthworm on the structure of the upper layer of the soil. Morphological analysis allowed to quantify the abundance of casts, soil compactness, pore morphology and connections between different pore classes. This approach was applied to experiments carried out at Yurimaguas (Peru), in four plots. Two of them had been inoculated with Pontoscolex corethrurus. In each case, one control plot was conducted without organic input, the other with crop residues and legume green manure. Morphological parameters were measured in fourteen horizontal sections within the first 3 cm. They showed compaction of soil surface due to cast coalescence in plots with earthworms but without organic input and illustrated the typical crumb structure induced by earthworms in plots with organic input.     

Water, Salt and Heat Influences on Carbon and Nitrogen Dynamics in Seasonally Frozen Soils in Hetao Irrigation District, Inner Mongolia, China

To investigate carbon (C) and nitrogen (N) dynamics in seasonally frozen soils under saline and shallow groundwater supply conditions, in-situ lysimeter experiments with different groundwater table depths (WTD=1.8 and 2.2 m) were conducted in Inner Mongolia, China during the wintertime of 2012-2013. Changes in soil organic C and total N in multiple layers during various periods, as well as their relationships with soil water, salt, and heat dynamics were analyzed. Accumulation of soil organic C and total N during freezing periods was strongly related to water and salt accumulation under temperature and water potential gradients. Water and salt showed direct influences on soil C and N dynamics by transporting them to upper layer and changing soil microbial activity. Salt accumulation in the upper layer during freezing and thawing of soil affected microbial activity by lowering osmotic potential, resulting in lower C/N ratio. Nitrogen in soil tended to be more mobile with water during freezing and thawing than organic C, and the groundwater table also served as a water source for consecutive upward transport of dissolved N and C. The changes in C and N in the upper 10 cm soil layer served as a good sign for identification of water and salt influences on soil microbial activity during freezing/thawing.     

土著菌群与蚯蚓肠道菌群共享核心物种协同抵御灭蚁灵胁迫研究

摘 要：灭蚁灵是一类高毒性的有机氯农药，当灭蚁灵通过直接或间接的人为途径进入到土壤生态环境系统后，会对生物体产生显著的毒害作用。土著菌群与蚯蚓肠道菌群都是对外源农药极其敏锐的感知受体，然而，它们对于抵御灭蚁灵毒害作用的微生物响应机制尚不清楚，值得探究。因而，本研究采集实际场地中不同梯度浓度（0~27.7 mg/kg）灭蚁灵污染土壤，设置蚯蚓土培实验，采用高通量测序技术，分析蚯蚓肠道菌群和土著菌群的结构和功能；通过MetagenomeSeq分析、LEfSe（Linear Discriminant Analysis Effect Size）分析和随机森林（Random Forests）分析以及网络分析，识别其核心类群。发现：1）灭蚁灵胁迫下蚯蚓肠道菌群相较之土著菌群的结构、组成受到的扰动更显著（p < 0.05）；2）不同梯度灭蚁灵胁迫下，蚯蚓肠道菌群和土著菌群组合存在稳定的核心物种，主要为气单胞菌属（Aeromonas）、黄杆菌属（Flavobacterium）、盖勒氏菌属（Gallerella）、微枝形杆菌属（Microvirga）、地杆菌属（Pedobacter）、亨氏菌（Ramlibacter）、Zavarzinella；3）这些核心种群在互作网络的平均度中心性、紧密中心性、特征向量中心性分别为136.72、0.44、0.52，均高于非核心种群的对应指标（91.52、0.42、0.33），表明核心种群具有更高的网络连通性，且此类核心种群具有碳氮转化和农药降解能力，说明蚯蚓肠道菌群和土著菌群可以通过共享核心物种与其它微生物联系紧密，具备发挥农药降解代谢的潜在功能，实现协同抵御土壤中灭蚁灵胁迫。本研究结果可为探明土著菌群与蚯蚓肠道菌群共享核心物种在抵御土壤中有机氯农药毒害作用的协同机制，提供新的科学认识。     

Phytolith transport in soil: a laboratory study on intact soil cores

Column experiments on phytolith transport were conducted to assess the partial contributions of water percolation and earthworm activity to phytolith transport in loamy and sandy soils. Six intact cores of a loamy sandy Haplic Cambisol and nine cores of a silty loamy Stagnic Luvisol were excavated. With the Luvisol, three treatments were perfomed: a percolation treatment with periodic irrigation, but without earthworms, a percolation and earthworm treatment with periodic irrigation and earthworms (Aporrectodea caliginosa) and a control. The Cambisol cores did not contain earthworms and hence only percolation and control treatments were tested. The phytoliths of common reed (Phragmites australis) were labelled with the fluorescent dye fluorescein isothiocyanate and applied to the soil surface of each core. Except for the control treatment, 3600 mm of water was applied over 6 months. In the Cambisol, the weighted mean transport distance of phytoliths was significantly greater with percolation (2.2 ± 0.1 cm) than in the control (0.9 ± 0.3 cm), indicating that water percolation is a driving mechanism of phytolith transport. In the Luvisol, the difference in mean transport depth between control and percolation treatments (1.0 ± 0.2 and 1.5 ± 0.3 cm) was not significant. The earthworms did not affect the mean transport distance of phytoliths in the Luvisol, but the phytolith concentrations in the leachates were significantly greater and their size distribution did not change with soil depth as observed in the percolation treatment without earthworms. Further studies are required to quantify the effect of earthworms on phytolith transport.     

三峡库区茶园坡面土壤水分空间分布特征及对降雨补给的响应

利用高频率(5 min)的土壤水分探针和自动气象站监测三峡库区典型茶园坡面与林地坡面的土壤水分变化过程及其对降雨的响应，明确了林地和茶园土壤水分变化的规律，揭示了土地利用方式和微地形对土壤水分和降雨储蓄的影响机制。结果表明：(1)在时间上，茶园和林地土壤含水率随降雨量的变化而改变，土壤含水率随土层深度呈现“W”型和“S”型变化。土壤含水率年内变异系数随着土层深度的增加而降低，表层土壤(10 cm)含水率为中等变异水平(10%相似文献   

The effect of tillage type and cropping system on earthworm communities, macroporosity and water infiltration

To test the assumption that changes to earthworm communities subsequently affect macroporosity and then soil water infiltration, we carried out a 3 year study of the earthworm communities in a experimental site having six experimental treatments: 2 tillage management systems and 3 cropping systems. The tillage management was either conventional (CT; annual mouldboard ploughing up to −30 cm depth) or reduced (RT; rotary harrow up to −7 cm depth). The 3 cropping systems were established to obtain a wide range of soil compaction intensities depending on the crop rotations and the rules of decision making. In the spring of 2005, the impact of these different treatments on earthworm induced macroporosity and water infiltration was studied. During the 3 years of observation, tillage management had a significant effect on bulk density (1.27 in CT and 1.49 mg m⁻³ in RT) whereas cropping system had a significant effect on bulk density in RT plots only. Tillage management did not significantly affect earthworm abundance but significantly influenced the ecological type of earthworms found in each plot (anecic were more abundant in RT). On the contrary cropping system did have a significant negative effect on earthworm abundance (104 and 129 ind. m⁻² in the less and most compacted plots, respectively). Significantly higher numbers of Aporrectodea giardi and lower numbers of Aporrectodea caliginosa were found in the most compacted plots. CT affected all classes of porosity leading to a significant decrease in the number of pores and their continuity. Only larger pores, with a diameter superior to 6 mm, however, were adversely affected by soil compaction. Tillage management did not change water infiltration, probably because the increase in macroporosity in RT plots was offset by a significant increase in soil bulk density. However, cropping system had a significant effect on water infiltration (119 vs 79 mm h⁻¹ in the less and most compacted plots, respectively). In RT plots, a significant correlation was observed between larger macropores (diameter > 6 mm) and water infiltration illustrating the potential positive effect of earthworms in these plots.     

Impact of ecologically different earthworm species on soil water characteristics

A laboratory experiment was performed to assess the impact of ecologically different earthworm species on soil water characteristics, such as soil tension, water content, and water infiltration rate. Three earthworm species (Lumbricus rubellus, Aporrectodea caliginosa, Lumbricus terrestris) were exposed in soil columns (diameter 30 cm, height 50 cm) for 100 days with a total fresh earthworm biomass of 22.7 ± 0.4 g per column, each in duplicate. Each column was equipped with tensiometers at 10 and 40 cm and FD-probes at 10 cm depth, to continuously measure the temporal development of soil tension and soil moisture. Additionally, 30 g of sieved and rewetted horse manure was placed on the soil surface as a food source. Precipitation events (10 mm) were simulated at day 28 and day 64. At the end of the experiment the water infiltration rate and the runoff at 55 cm depth were determined.The results showed considerable evidence, that ecologically different earthworms modify soil water characteristics in different ways. The anecic L. terrestris and the endogeic A. caliginosa showed the tendency to enhance the drying of the topsoil and subsoil. Their intensive and deep burrowing activity might enhance the exchange of water vapor due to a better aeration in soil. In contrast, the epigeic L. rubellus tended to enhance the storage of soil moisture in the topsoil, which might be linked to lower rates of litter loss from soil surface and thus a thicker litter layer remaining. A. caliginosa led to considerable higher water infiltration rates and faster water discharges in the subsoil, relative to the other species, probably due to a high soil dwelling activity.     

矿区生态修复过程中不同立地类型土壤水动力学特性

[目的]揭示矿区不同立地土壤水动力学特性及其影响因素,为矿区生态环境恢复治理提供科学依据。[方法]基于矿区不同立地类型土壤水分特征曲线、非饱和导水率、孔隙度与紧实度等监测试验,揭示不同立地类型土壤持水性、有效水含量和导水特性等变化规律。[结果]土壤持水性和供水性在受损区<修复3a区<修复5a区<修复10a区<修复15a区<未干扰区,但修复区20—40cm土壤持水性、供水性较0—20cm土壤低,修复效果不明显;土壤结构改善效果遵循受损区<修复区<未干扰区的变化规律,且修复区亚表层土壤结构改善效果不明显。采用指数函数拟合吸力和非饱和导水率效果较好(r2>0.95),相同吸力下,容重大而非饱和导水率较小;非饱和导水率和容重呈负相关,和孔隙度呈正相关且相关性随吸力增加降低。矿区0—20cm易有效含水量呈现受损区<修复3a区<修复5a区<修复10a区<未干扰区<修复15a区,但修复区20—40cm土层易有效水含量较0—20cm小。[结论]土壤易有效水含量和容重、紧实度呈负相关关系,与总孔隙度、黏粒含量呈正相关关系。修复后土壤结构有所改善,持蓄调节水分能力有所提高。     

基于灰色关联分析的砒砂岩区不同林龄沙棘的改土效应

[目的]探究不同林龄沙棘对其下土壤的改良效果,为砒砂岩区人工沙棘林生态建设、恢复和重建提供理论依据。[方法]以内蒙古达拉特旗典型砒砂岩区不同林龄沙棘林为研究对象,利用灰色度关联分析法,对沟坡阳坡1～7 a沙棘林0—40 cm土层土壤物理性质(土壤含水量、土壤容重、土壤总孔隙度、土壤比重、土壤毛管孔隙度、土壤非毛管孔隙度、土壤饱和持水量、土壤最大毛管持水量)进行测定,并以周边荒坡作为对照(CK),对不同林龄沙棘林对砒砂岩土壤的改土效应进行分析。[结果]土壤含水量、土壤总孔隙度随沙棘林龄增加而增大,随土壤深度增加而减少,土壤容重与之相反;不同林龄沙棘能增强土壤持水能力,并且4～7 a沙棘持水能力大于1～3 a沙棘持水能力。[结论]在砒砂岩区营建人工沙棘林有利于土壤改良,不同林龄沙棘对土壤改良作用主要作用于0—10 cm和10—20 cm土层。