Earthworm Density Research Articles

Three-dimensional mapping of earthworm (Lumbricus terrestris) seed transport

Transport by earthworms contributes to the secondary dispersal of seeds and influences patterns of plant community structure and function. To date, however, research on earthworm seed dispersal has focused primarily on vertical transport and the collection of seeds into middens at the soil surface, with no efforts to map horizontal distribution after burial. This study used an emergence depth assay and depth-stratified seedling emergence from soil microcosm cross-sections to map earthworm seed transport in three dimensions using commercial grass seed and the anecic earthworm Lumbricus terrestris L. While specific seed burial profiles should not be considered representative of burial under field conditions (due primarily to high earthworm densities under artificially limiting microcosm conditions), we created what we believe to be the first three-dimensional and most detailed map of earthworm seed burial, visualizing and quantifying the ability of L. terrestris to redistribute seed both vertically and horizontally throughout the soil profile. L. terrestris buried 6.5 to 17.4% of the total seeds and reduced aboveground grass biomass by 59–65 %. Vertically, L. terrestris buried seeds evenly across the 13 cm deep microcosms. Horizontally, L. terrestris aggregated seeds into small clusters aligned obliquely across soil depths, which suggest seeds being deposited in burrow walls (variance to mean ratio: 3.39 ± 2.49). Seeds were aggregated regardless of L. terrestris density but covered a greater cross-sectional area of the soil profile when more earthworms were present. Spatial patterning of shallow buried seed still capable of emergence is a newly described mechanism by which L. terrestris might influence the spatial structure of plant communities.

Environmental determinants of plant species diversity in organic and conventional vineyards

The factors affecting the plant biodiversity in organic (manure application) and conventional vineyards (variety “Agiorgitiko for both) in southern Greece were examined separately for each vineyard type. The index for plant biodiversity was chosen to be the Shannon one (SH). The Pearson correlation coefficients disclosed that the common factors in both vineyards types affecting the SH were the concentrations of the soil organic C and organic N, the nitrates –N, the available (Olsen) P, available Cu, exchangeable K and the CaCO3 percentage. The C/N ratio in soils affected positively and significantly the SH index in both vineyards types. That means that the supply of N is not a problem with regard to decomposition but the organic C as a source of energy can be a limiting factor to plant diversity. The earthworm population density in the two vineyards types was also a significant positive factor to the SH. The concentrations of the available Mg, Zn and ammonium-N in soils affected the SH index significantly only in the conventional vineyards although their concentrations in soils did not differ. We can conclude that chemical fertilization can also affect plant variability.

Oil palm and rubber expansion facilitates earthworm invasion in Indonesia

Deforestation, plantation expansion and other human activities in tropical ecosystems are often associated with biological invasions. These processes have been studied for above-ground organisms, but associated changes below the ground have received little attention. We surveyed rainforest and plantation systems in Jambi province, Sumatra, Indonesia, to investigate effects of land-use change on the diversity and abundance of earthworms—a major group of soil-ecosystem engineers that often is associated with human activities. Density and biomass of earthworms increased 4—30-fold in oil palm and rubber monoculture plantations compared to rainforest. Despite much higher abundance, earthworm communities in plantations were less diverse and dominated by the peregrine morphospecies Pontoscolex corethrurus, often recorded as invasive. Considering the high deforestation rate in Indonesia, invasive earthworms are expected to dominate soil communities across the region in the near future, in lieu of native soil biodiversity. Ecologically-friendly management approaches, increasing structural habitat complexity and plant diversity, may foster beneficial effects of invasive earthworms on plant growth while mitigating negative effects on below-ground biodiversity and the functioning of the native soil animal community.

Effects of winter wheat and endogeic earthworms on soil physical and hydraulic properties

Earthworms directly and indirectly affect soil physico-hydraulic properties. We studied interactions between winter wheat and the common European earthworm Allolobophora chlorotica, testing for impacts upon soil physico-hydraulic properties. Column experiments with three different soil textures and field-relevant earthworm densities were conducted. Saturated hydraulic conductivity (Ks) increased over time in earthworm treatments, with the increase occurring most rapidly in the plant plus earthworm treatment. After 16 weeks Ks had increased in the treatment comprising both plants and earthworms by factors of 12, 34 and 39 in the loam, silt-loam and sandy-loam soils respectively relative to controls. The presence of earthworms resulted in an 88.5% increase in the contribution of pores >3 mm diameter to water flow. In the majority of treatments, soil water-holding capacity and percentage water-stable aggregates of the 5 cm topsoil in both the plant and the earthworm treatments increased significantly compared to controls with the plant plus earthworm treatment showing the greatest increase. Plant growth was greater in the presence than absence of earthworms. Our study shows synergistic and additive effects on soil physical properties in the presence of both earthworms and plants compared to when only earthworms or plants are present. It shows that it is not just vertical-burrowing anecic earthworms that can have a significant effect on soil hydraulic properties but that field-relevant densities of endogeic earthworms such as A. chlorotica can also contribute to soil water flow regulation.

EARTHWORM COMMUNITIES (OLIGOCHAETA, LUMBRICIDAE) OF PINE FORESTS AND SMALL FOLIAGE FORESTS IN THE FOREST-STEPPE OB’ REGION

Earthworms form an essential group of soil macrofauna that performs a number of ecosystem functions in forests. Studies of the species composition and population density of earthworms were conducted in many regions of Russia; however, the fauna of Lumbricidae of Novosibirsk area remained unexplored for a long time. The objective of this work is to carry out a comparative analysis of earthworm population in coniferous and small foliage forests of the forest-steppe Ob region (Novosibirsk area) and to identify the correlation between the fauna composition and the basic physical and chemical properties of the soil. The study was conducted in pine forests and birch-aspen forests. The main method of registration was layer-by-layer excavation of soil with hand sorting of soil samples and analysis of forest deadwood. Some soil parameters were also measured. Data of the species composition and population density of earthworms for each habitat are given. The studied habitats were classified according to the ratio of the earthworm living forms. It was found that soil humidity is the most significant factor for the group of epigeiс and epi-endogeiс species. The diversity of epigeiс and epi-endogeiс earthworm species in forests is largely supported by deadwood. The Asian subspecies Eisenia nordenskioldi nordenskioldi was subjected to morphometric analysis confirming its characteristic polymorphism.

Trees and herbaceous vegetation strips both contribute to changes in soil fertility and soil organism communities in an agroforestry system

Alley cropping systems introduce herbaceous strips planted with trees into cropped fields. While such systems may have a positive effect on soil fertility, the respective roles of the trees and the herbaceous vegetation in shaping this effect remain unclear. We investigated the effect of the distance from herbaceous strips with or without walnut trees on soil fertility and earthworm communities in a 20 year old Mediterranean plot intercropped with tomatoes. We determined the effects of i) the presence of trees, ii) the distance from the herbaceous strip (0 m, 1 m and 2.5 m) and iii) the distance from the tree on microbial biomass and respiration, earthworm density and soil C, N and P contents in the 0–25 cm layer at three sampling seasons. Herbaceous strips presented a higher microbial biomass C related to soil organic carbon, a lower microbial metabolic quotient, and a higher density of earthworms than the crop alley regardless of tree presence. Soil organic carbon content increased in the presence of trees. Available P and microbial biomass increased at 1 m from the tree in the HS. Earthworm density and microbial biomass were higher at 1 m than at 2.5 m from the HS. Herbaceous strips were an effective shelter for earthworms and fostered a high and efficient microbial biomass throughout the year, with or without trees, probably due to diversified vegetation and no soil disturbance. The mechanisms by which these changes could impact the crop alley remain to be studied.

Earthworms in past and present agricultural landscapes of Hebridean Scotland

The Hebrides of Scotland constitute a unique set of island environments with a long history of human settlement and agriculture. Earthworm community surveys were undertaken in selected agricultural landscapes of Inner (Isle of Rum) and Outer (North and South Uist) Hebrides. On North Uist, earthworms were sampled from areas of Blackland (organic, anthropic, acidic agricultural soils) and on South Uist in machair (sandy, fertile, low-lying grassy pasture). Specific grassland and cultivated areas with various organic additions - including dung and seaweed - were targeted, using hand-sorting of soil for earthworms plus mustard vermifuge extraction. Work on Rum investigated earthworms in ridge and furrow (lazybed) agricultural systems, abandoned almost 200 years ago and since uncultivated, but grazed by ungulates. On the Uists, nine earthworm species were identified, representing all three ecological categories, but dominated by the epigeics, Dendrobaena octaedra and Lumbricus rubellus. Densities and biomasses across Blackland soils ranged from 10-130 ind. m−2 and 2.3–33.7 g m−2, respectively. Here, 5 species were present, and management had a significant effect on species richness and abundance with most earthworms present in recently restored lazybeds. In the machair soils, the corresponding measurements were 4–220 ind. m−2 and 0.8–89.0 g m−2. Significantly higher earthworm densities and biomasses were recovered below cattle dung pats compared with dung-free areas. Cultivated areas in machair were less diverse and had lower earthworm densities than uncultivated. On Rum, ridge and furrow abundances did not differ clearly with 24–102 and 34–112 ind. m−2 respectively and biomasses of 7.4–26.3 and 8.8–30.8 g m−2. Here, Aporrectodea caliginosa (49%), L. rubellus (23%) and Dendrodrilus rubidus (19%) dominated of the seven species found. Further research on earthworms in the Hebrides is warranted.

NO-TILL TECHNOLOGY AS A FACTOR OF ACTIVITY OF SOIL INVERTEBRATE IN AGRICULTURAL CHERNOZEMS OF STAVROPOL REGION

Soil macro- and mesofauna is highly sensitive to various methods of agricultural cultivation, therefore soil invertebrates are used as bioindicators of agrocenoses ecological condition. Since the macro- and mesofauna to a largely extent control the water balance of the soil and participate in the formation of humus, special attention should be paid to soil fauna in arid regions, primarily in the Cernozem Region. In this work, for the first time, an integrated estimation of the population density and ecological and functional diversity of macro- and mesofauna of Vorony-Calcic Chernozem in the Stavropol region is given. The possibility of using these groups of invertebrates as bioindicators of the ecological status of agrocenoses has been shown. It is proved that the use of no-till technology stimulates the activity and number of all groups of macro- and mesofauna. The purpose of the work is to estimate the numbers and taxonomic diversity of ecological and functional groups of macro- and mesofauna with various technologies of soil cultivation (traditional plowing and no-till) with and without mineral fertilizers on the agrochernozems of the Stavropol region. Experiments on research no-till technology were carried out in 2012-2019 in an experimental farm of the North Caucasus Federal Scientific Agrarian Center (Shpakovsky district of the Stavropol region). In 2019 we studied plots of fields with three types of factors: tillage (plowing and no-till technology); presence/absence of fertilizers; agricultural crops. The soil is Vorony-Calcic Chernozem. Crop rotation: maize (Zea mays L.) variety Mashuk, soybean (Glycine max L.) variety Duniza (until 2018), which was replaced later by peas (Pisum sativum L.) variety Phaeton, winter wheat (Triticum aestivum L.) variety Deya, sunflower (Helianthus annuus L.) variety Bagrat. Deposit soil near the experimental fields served as a control. Fertilizers were applied at the time of sowing (N160P90K60 for winter wheat, N72P58K32 for sunflower, N80P48K48 for corn, and N60P60K60 for soybeans and peas). The soil macrofauna was registered by the method of excavation of areas 25×25×30 cm and manual analysis of soil samples. Soil mesofauna was isolated from the soil monolith by the method of eklectors, identified and counted using a microscope Biomed-5 PR LUM (Russia) at a magnification of ×40. Most abundant among the macrofauna were centipedes (Myriapoda), adults and larvae of coleopterans (Coleoptera), spiders (Araneae) and earthworms (Lumbricidae). Aporrectodea caliginosa dominated among earthworms, while single of A. roseawere found only in deposit lands. The minimum number of A. caliginosa (32 ind/m2) was recorded under peas and sunflower with traditional plowing, the maximum — under corn on no-till plots and on plowed plots (556 and 512 ind/m2, respectively). In general, the number of earthworms was higher in no-till fields under all crops (excluding sunflower) in comparison with plowed plots. Among other groups of soil macrofauna, the most numerous were centipedes (up to 1500 ind/m2), as well as spiders (up to 500 ind/m2) and beetles (up to 500 ind/m2). Woodlice (Oniscidea) and molluscs (Gastropoda) were also encountered. The density of centipedes, spiders, coleoptera and earthworms was always higher for no-till options than for plowed fields, regardless of crop. The application of mineral fertilizers, as a rule, reduced the number and diversity of the macrofauna representatives. Among the mesofauna, ticks (Acari) and collembolans (Collembola) prevailed in terms of abundance and diversity. Mesofauna of no-till fields was taxonomically more diverse than plowed plots. The minimum number of mesofauna representative was found under peas and corn, the maximum — under winter wheat and sunflower. In general, the distribution of soil invertebrates (macro- and mesofauna) was significantly influenced by the method of soil cultivation, however, the agricultural culture often influenced the abundance indicators. The use of fertilizers reduced the biodiversity of macrofauna and decreased its number in all plots, regardless of the method of soil cultivation.

ТЕХНОЛОГИЯ NO-TILL КАК ФАКТОР АКТИВНОСТИ ПОЧВЕННЫХ БЕСПОЗВОНОЧНЫХ В АГРОЧЕРНОЗЕМАХ СТАВРОПОЛЬСКОГО КРАЯ

Soil macro- and mesofauna is highly sensitive to various methods of agricultural cultivation, therefore soil invertebrates are used as bioindicators of agrocenoses ecological condition. Since the macro- and mesofauna to a largely extent control the water balance of the soil and participate in the formation of humus, special attention should be paid to soil fauna in arid regions, primarily in the Cernozem Region. In this work, for the first time, an integrated estimation of the population density and ecological and functional diversity of macro- and mesofauna of Vorony-Calcic Chernozem in the Stavropol region is given. The possibility of using these groups of invertebrates as bioindicators of the ecological status of agrocenoses has been shown. It is proved that the use of no-till technology stimulates the activity and number of all groups of macro- and mesofauna. The purpose of the work is to estimate the numbers and taxonomic diversity of ecological and functional groups of macro- and mesofauna with various technologies of soil cultivation (traditional plowing and no-till) with and without mineral fertilizers on the agrochernozems of the Stavropol region. Experiments on research no-till technology were carried out in 2012-2019 in an experimental farm of the North Caucasus Federal Scientific Agrarian Center (Shpakovsky district of the Stavropol region). In 2019 we studied plots of fields with three types of factors: tillage (plowing and no-till technology); presence/absence of fertilizers; agricultural crops. The soil is Vorony-Calcic Chernozem. Crop rotation: maize (Zea mays L.) variety Mashuk, soybean (Glycine max L.) variety Duniza (until 2018), which was replaced later by peas (Pisum sativum L.) variety Phaeton, winter wheat (Triticum aestivum L.) variety Deya, sunflower (Helianthus annuus L.) variety Bagrat. Deposit soil near the experimental fields served as a control. Fertilizers were applied at the time of sowing (N160P90K60 for winter wheat, N72P58K32 for sunflower, N80P48K48 for corn, and N60P60K60 for soybeans and peas). The soil macrofauna was registered by the method of excavation of areas 25×25×30 cm and manual analysis of soil samples. Soil mesofauna was isolated from the soil monolith by the method of eklectors, identified and counted using a microscope Biomed-5 PR LUM (Russia) at a magnification of ×40. Most abundant among the macrofauna were centipedes (Myriapoda), adults and larvae of coleopterans (Coleoptera), spiders (Araneae) and earthworms (Lumbricidae). Aporrectodea caliginosa dominated among earthworms, while single of A. roseawere found only in deposit lands. The minimum number of A. caliginosa (32 ind/m2) was recorded under peas and sunflower with traditional plowing, the maximum — under corn on no-till plots and on plowed plots (556 and 512 ind/m2, respectively). In general, the number of earthworms was higher in no-till fields under all crops (excluding sunflower) in comparison with plowed plots. Among other groups of soil macrofauna, the most numerous were centipedes (up to 1500 ind/m2), as well as spiders (up to 500 ind/m2) and beetles (up to 500 ind/m2). Woodlice (Oniscidea) and molluscs (Gastropoda) were also encountered. The density of centipedes, spiders, coleoptera and earthworms was always higher for no-till options than for plowed fields, regardless of crop. The application of mineral fertilizers, as a rule, reduced the number and diversity of the macrofauna representatives. Among the mesofauna, ticks (Acari) and collembolans (Collembola) prevailed in terms of abundance and diversity. Mesofauna of no-till fields was taxonomically more diverse than plowed plots. The minimum number of mesofauna representative was found under peas and corn, the maximum — under winter wheat and sunflower. In general, the distribution of soil invertebrates (macro- and mesofauna) was significantly influenced by the method of soil cultivation, however, the agricultural culture often influenced the abundance indicators. The use of fertilizers reduced the biodiversity of macrofauna and decreased its number in all plots, regardless of the method of soil cultivation.

Effects of earthworm (Metaphire guillelmi) density on soil macropore and soil water content in typical Anthrosol soil

The burrowing activities of earthworms can change the soil macropore structure in terrestrial ecosystems. Studying the burrows structure and their effects on soil water movement may be crucial for exploring earthworm ecological functions and improving water use efficiency in farmlands in semi-humid areas. It was an experiment taken to assess the impact of anecic earthworm Metaphire guillelmi on the characteristics of soil macropore and soil water content (SWC). Earthworms with different densities (0, 3 and 10 in. in each column) were introduced in soil columns (height 38 cm, diameter 23 cm) for 33 days. The macropore characteristics were determined by X-ray computed tomography (CT). Results showed that increasing earthworm density increased the macroporosity and macropore number. The macropore number in the high-density earthworm treatment (HDE) was 1.3 times larger than that in columns with low-density earthworm (LDE). The diameter of soil macropores ranged from 2.12 mm to 7.30 mm. The mean macroporosities in HDE and LDE treatments were 1.35 % and 0.61 %, respectively. The soil pore morphology (mean macropore circularity, branch, junction and connectivity) was also improved by earthworms. The high number of macropores (45.30/N) and connectivity (0.05 cm−3) were observed in the column with high density of earthworms. Earthworms improved the soil macropores and macroporosity. The SWC linearly decreased with increasing earthworm density. A significant difference (P < 0.05) of SWC was observed between columns with earthworm (LDE and HDE) and those without earthworm (CK), especially at the 10–30 cm soil depth. The burrows generally open to the soil surface and increased water vapour transfer channels, thus accelerated soil evaporation. In areas with uneven rainfall, high earthworm density could aggravate the risk of seasonal drought at the plough layer, which is an important threaten for crop growth and yield.

Earthworm population dynamics in traditional slash and burn cultivation in Mizoram, Northeast India

Aim: This paper describes the influence of traditional slash and burn (shifting) cultivation on earthworm population structure and species diversity. Methodology: The study was conducted in a tropical hilly terrain natural forest in northeast India. The first year was taken as pre–cultivation phase. During second-year traditional slash and burn cultivation was carried out with rice (Oryza sativa) as the main crop, where local weeding practice using had hoe was done thrice. The land was left fallow in the third year. Earthworms were sampled from five random quadrats at monthly interval by digging and hand sorting method. Results: Nine species of earthworms belonging to three families were identified, out of which three epigeic species (P. excavatus, P. macintoshi and A. alexandri) were not recorded during the cultivation phase. There was a significant (p&lt;.05) reduction in earthworm density during the cultivation phase. M. houletti was the most dominant species in terms of density, while D. nepalensis was the most versatile in seasonal distribution. Shannon Index of diversity was lowest in the cultivation phase (H ̅=0.84, 1-D=0.46) as compared to pre-cultivation (H ̅=1.67, 1-D=0.76) and post-cultivation (H ̅=1.67, 1-D=0.77). Interpretation: The reason for negative effect of traditional slash and burn cultivation on earthworm population density and diversity could be due to multiple weeding practices resulting in the disturbance of surface soil that directly or indirectly affects earthworms. Key words: Earthworms, Epigeic species, Mizoram, Slash and burn cultivation, Soil, Weeding

Fate of deoxynivalenol (DON) and impact on the soil microflora and soil fauna

Fusarium graminearum is a plant-pathogenic fungus that causes the devastating disease “Fusarium head blight” (FHB) in cereal crops such as wheat (Triticum aestivum). It also contaminates grains with mycotoxins, including deoxynivalenol (DON), which turn toxic to humans and animals. This fungus overwinters in crop residues left in the field. The fate of mycotoxins in these crop residues in the soil and their ecological role are still unexplored. Therefore, our objective was to assess whether mycotoxins are maintained in the soil, impact the soil biome and benefit the survival of F. graminearum. A six-month study in microcosms was performed to examine the fate of DON in F. graminearum-contaminated wheat straw and soil, and its impact on soil communities. DON was extracted from straw and soil mixtures, and quantified by high-performance liquid chromatography (HPLC). Fusarium graminearum and total fungal and bacterial molecular biomasses were quantified using real-time polymerase chain reaction (Q-PCR). Nematode and earthworm densities were quantified through binocular observations. Changes in the genetic structure of fungi, bacteria, protozoa, and nematodes communities were determined by terminal restriction fragment length polymorphism (T-RFLP) analyses. Results revealed that DON disappeared from the straw and the soil over time. The rate of disappearance was accelerated when straw was incorporated into the soil and when microcosms contained earthworms. Fungal and bacterial biomass, first stimulated during the incorporation of straw, decreased after 2 weeks and until the end of the experiment (24 weeks). It decreased more strongly in the presence of DON. This negative impact of DON was temporary and at the end of the experiment, the bacterial and fungal biomass was higher in the treatments that received DON than in the other treatments while the population of F. graminearum was unaffected. Similarly, DON modified the community structures of fungi, bacteria and protozoa to various extents but not that of nematodes. DON-contaminated straw was found attractive for earthworms, and its presence stimulated their reproduction or cocoon hatching. The major conclusion is that DON briefly affected soil communities, disappeared over time and gave no observable advantage to soil-borne F. graminearum populations.

Population Of Bacteria In Soil Dystrudepts Under Oil Palm In The Application Of Organic Mulch And Earthworm

Research on the effect of organic mulch and earthworms under oil palm plantation on the total population bacteria is still scarce. The study aims to analyze the effect of organich mulch, earthworm desity, and the interaction between organich mulch and earthworm density on the total population bacteria. The research was carried out in May – August 2019. This research was a 3 x 4 factorial experiment which was placed according to a Split Plot Design with the basic design of Randomized Block Design, each treatment was repeated 3 times. Organic mulch as the main plot are 3 type, namely: M1 (M. bracteata), M2 (oil palm empty fruit brunches/ OPEFB) and M3 (oil palm midrib). The density of earthworms as subplots consists of 4 levels, namely: C0 (0 worms/m2), C1 (35 worms/m2), C2 (50 worms/m2) and C3 (65 worms/m2). The data were analyzed using analysis of variance. If the treatment is significantly different, the treatment was tested by Duncan’s at 5% significance level. The results showed that oil palm midrib organic mulch can increase the total population of fungi and bacteria compared to M. bracteata and OPFEB. The earthworms density 50 and 65 worms/m2 can increase the total bacterial population compared to other earthworm densities. The combination of oil palm midrib with earthworms density 50 and 65 worms/m2 can increase the total population of bacteria

Evaluación de la calidad de suelo: generación e interpretación de indicadores

Las prácticas de manejo del suelo alteran sus propiedades, especialmente cuando las entradas de energía al sistema suelo-planta son menores que las salidas, o su resiliencia es incapaz de regresarlo al estado previo a la intervención. Cuando las alteraciones se acercan a los límites de tolerancia del sistema suelo aparecen factores que limitan la producción. Los cambios se pueden establecer mediante indicadores e índices de calidad. Éstos muestran la dirección del cambio con el tiempo. El objetivo de este trabajo fue evaluar la calidad de suelo actual en cuatro ejidos agrícolas de Tepeaca, Puebla, México, que tienen siglos de dedicación a la producción agrícola. Se investigó su historia, los patrones de cultivo más comunes y las clases de tierra dominantes, def inidas con la participación de los productores locales. Se analizaron propiedades físicas, químicas y biológicas de suelos sometidos a diferentes manejos y se def inieron los indicadores de calidad. Los criterios de selección para los sitios de muestreo, fueron los patrones de cultivo más frecuentes: (i) flor de corte, (ii) hortalizas continuas, y (iii) hortalizas con descanso durante temporada de ausencia de lluvias. Como referencia se tuvo los mismos suelos, pero sin manejo. Las propiedades seleccionadas como indicadores fueron pH, conductividad eléctrica materia orgánica del suelo, estabilidad de agregados en húmedo, fósforo extraíble Olsen, hierro extraíble con DTPA, densidad de lombrices. Las cuatro primeras fueron sensibles para diferenciar entre suelos sin alterar (no cultivados) y los suelos cultivados. Las cuatro últimas fueron escogidas por mostrar tasas de cambio en función de los patrones de cultivo, lo que indica la necesidad de promover estrategias de manejo agronómico. Con ellas se construyó un índice de calidad de suelo que permite establecer la dirección del cambio que experimentará la calidad del suelo al modif icar uno o más indicadores.

Earthworm Inoculation Improves Upland Rice Crop Yield and Other Agrosystem Services in Madagascar

The effects of earthworm inoculation and cropping systems on upland rice systems were examined over a four-year period in the Highlands of Madagascar. Each year, endogeic earthworms Pontoscolex corethrurus (Rhinodrilidae) were inoculated (EW+) at a density of 75 ind m−2 or were not inoculated (EW0). Inoculation was tested in three cropping systems: conservation agriculture (CA) and traditional tillage with or without residues restitution. Soil and plant properties were measured during the first three years while soil biological properties were assessed at the fourth year. At the end of the experiment, earthworm density was three-fold higher in EW+ than in EW0, demonstrating the success of the inoculation. Earthworm density was more important in CA than in tillage systems. Earthworm inoculation had higher significant effects on soil and plant properties than cropping systems. Earthworm inoculation had positive effects on soil macroaggregation (+43%), aboveground biomass (+27%), rice grain yield (+45%), and N grain amount (+43%). Intensifying earthworm activity in field conditions to meet the challenge of ecological transition is supported by our study.

Earthworm density differences among tallgrass prairies over time in the Ozark Highlands

AbstractTo mitigate the loss of tallgrass prairies through fragmentation and conversion to other land uses, prairie restoration efforts have been undertaken to reclaim areas that have been previously used for agricultural production. Earthworms are a key component of the soil ecology of natural, undisturbed ecosystems. However, limited research exists on earthworm populations in prairie restorations and how earthworm densities may change over time. The objectives of this study were (a) to evaluate earthworm densities in the upper 20 cm of soil over time (i.e., May 2007 and May 2019) in a native prairie and chronosequence of three prairie restorations (i.e., established in 1979, 2000, and 2002), and (b) to identify relationships between earthworm (i.e., juvenile, adult, and total) density and soil physical and chemical properties. Juvenile (P = .03) earthworm density decreased 25 and 35% and total (P = .03) earthworm density decreased by 33 and 42% in the 2000 and 2002 restorations, respectively, from May 2007 to May 2019. Adult earthworm density did not change over time (P &gt; .05) in any prairie ecosystem. Combined across prairie sites, adult earthworm density was positively correlated (P &lt; .05) with sand content (r = .49) and pH (r = .49) and negatively correlated (P &lt; .05) with silt (r = –.56) and sulfur content (r = –.47). To promote earthworm densities similar to native prairies, consideration should be given to numerous soil properties for a successful restoration.

Earthworm differences among mound positions in native prairies in the Ozark Highlands

Mounded, tallgrass prairie ecosystems are a unique, endangered ecosystem due to severe disturbance for agricultural production and/or urban expansion. Limited research exists on earthworm (Lumbricus terrestris) dynamics in mounded, tallgrass prairies, particularly in the Ozark Highlands region of northwestern Arkansas. The objectives of this study were to evaluate the effects of soil moisture regime (SMR), landscape position (LP), and sample date on earthworm densities in the top 20 cm of soil in two mounded, native prairies in the Ozark Highlands region of northwestern Arkansas. Juvenile and total earthworm densities were five times greater (P < .05) in the udic- and aquic-inter-mound combinations than any other SMR-LP combination in October 2018 and May 2019, respectively. Adult earthworm densities were two times greater (P < .05) in the aquic-inter-mound at Searles Prairie than any other SMR-LP combination in either mounded prairie. Juvenile earthworm densities were three times greater (P < .05) in May 2019 than in May 2018 at Chesney Prairie, but adult and total earthworm density did not change over the same period of time. Combined across all data, juvenile and total earthworm densities were positively correlated (P < .05) with moisture (r = .33 and .34, respectively), Ca (r = .20 and .21, respectively), and Fe (r = .53 and .52, respectively), but negatively correlated (P < .05) with Mn (r = –.34 and –.32, respectively). Results of this study extended overall understanding of earthworm population distributions and dynamics in mounded prairie systems.

秦岭山地蚯蚓数量分布及其与土壤环境因子的关系研究

蚯蚓是土壤中典型的大型动物，在有机质分解、营养循环和土壤形成中起着极为重要的作用，具有重要的生态功能。运用样方调查法，对秦岭山地4种不同土地类型的蚯蚓密度、生物量进行了调查，分析了蚯蚓种群特征与土壤性质之间的关系。结果表明，不同土地类型下，土壤蚯蚓密度(P Earthworms are typical large animals in the soil, play an extremely important role in the decom-position of organic matter, nutrient cycling and soil formation, and have an important ecological function. The density and biomass of earthworms in 4 different land types in the Qinling Mountains were investigated using the sample survey method. And the relationship between the char-acteristics of earthworm populations and soil properties was analyzed. The results showed that there were significant differences in soil earthworm density (P

Earthworms as an Ecological Indicator of Soil Recovery after Mechanized Logging Operations in Mixed Beech Forests

Soil damage caused by logging operations conducted to obtain and maximize economic benefits has been established as having long-term effects on forest soil quality and productivity. However, a comprehensive study of the impact of logging operations on earthworms as a criterion for soil recovery has never been conducted in the Hyrcanian forests of Iran. The aim of this study was to determine the changes in soil biological properties (earthworm density and biomass) and its recovery process under the influence of traffic intensity, slope and soil depth in various intervals according to age after logging operations. Soil properties were compared among abandoned skid trails with different ages (i.e., 3, 10, 20, and 25 years) and an undisturbed area. The results showed that earthworm density and biomass in the high traffic intensity and slope class of 20–30% at the 10–20 cm depth of the soil had the lowest value compared to the other treatments. Twenty-five years after the logging operations, the earthworm density at soil depth of 0–10 and 10–20 cm was 28.4% (0.48 ind. m−2) and 38.6% (0.35 ind. m−2), which were less than those of the undisturbed area, respectively. Meanwhile, the earthworm biomass at a soil depth of 0–10 and 10–20 cm was 30.5% (2.05 mg m−2) and 40.5% (1.54 mg m−2) less than the values of the undisturbed area, respectively. The earthworm density and biomass were positively correlated with total porosity, organic carbon and nitrogen content, while negatively correlated with soil bulk density and C/N ratio. According to the results, 25 years after logging operations, the earthworm density and biomass on the skid trails were recovered, but they were significantly different with the undisturbed area. Therefore, full recovery of soil biological properties (i.e., earthworm density and biomass) takes more than 25 years. The conclusions of our study reveal that the effects of logging operations on soil properties are of great significance, and our understanding of the mechanism of soil change and recovery demand that harvesting operations be extensively and properly implemented.

Impact of soil metals on earthworm communities from the perspectives of earthworm ecotypes and metal bioaccumulation

The current study elucidates the impact of soil metal contamination on earthworm communities at the ecotype level. A total of 292 earthworms belonging to 13 species were collected in metal-contaminated soils from Wanshou (WSC), Daxing (DXC) and Lupu (LPC) plots (1.40–6.60, 29.4–126, 251–336 and 91.9–109 mg/kg for soil Cd, Cu, Zn and Pb, respectively) in Hunan Province, southern China. The results showed that the total earthworm density and biomass significantly decreased along the increasing metal-contaminated gradient while epigeic earthworms became more dominant than anecic and endogeic earthworms. Redundancy analysis (RDA) showed that soil pH, total nitrogen and Cd concentration were the primary factors influencing earthworm communities, explaining 33.7%, 29.1% and 26.7% of the total variance, respectively. In addition, epigeic earthworm Metaphire californica bioaccumulated more Cd (0.27–0.60 mmol/kg), while endogeic earthworm Amynthas hupeiensis and anecic earthworm Amynthas asacceus bioaccumulated more Cu (0.55–1.62 mmol/kg) and Zn (2.86–6.46 mmol/kg) from soil, respectively, which were related to their habit soils and showed the species-specific bioaccumulation features. Our study discovered the diverse responses of earthworm ecotypes to metal contamination and their specific features of metal bioaccumulation, provide insight for soil risk assessments and for biodiversity conservation from a niche partitioning perspective. CapsuleEarthworms of different ecotypes showed different responses to soil metal contamination and species-specific features of metal bioaccumulation.