Earthworm Diversity Research Articles

Mise en relation de la diversité des vers de terre et des caractéristiques du sol de Thua Thien Hue (Centre Vietnam)

Etant donné leur texture sableuse, les sols de la zone côtière de la province de Thua Thien Hue au Centre Vietnam présentent un milieu particulier pour le développement des organismes du sol, dont les vers de terre représentent 70% de la biomasse. Cette étude met en relation les caractéristiques du sol et les communautés de vers de terre, après identification de ceux-ci. Sept espèces appartenant aux familles des Glossoscolecidae, des Megascolecidae et des Microchaetidae ont été relevées : Pontoscolex corethrurus, Glyphidrilus papillatus, Pheretima rodericensis, Pheretima danangana, Pheretima sp., Perionyx excavatus, et Lampito mauritii. Les Microchaetidae sont présents quelque soit la richesse du sol et constituent la famille dominante dans les sols acides à forte teneur en limon et argile. Les deux autres familles sont associées à des sols pauvres mais moins acides, riches en sable. Il ressort également de cette étude que le nombre de P. corethrurus est significativement plus important dans les vergers (AF) alors que L mauritii est significativement plus présent dans les sols avec des autres cultures que le riz (AC). G. papillatus, significativement plus abondant dans les friches, est la seule espèce retrouvée dans ce milieu. L'étude de la diversité (Indice de Shannon-Wiener) montre que les cultures autres que le riz (AC) présentent la plus grande diversité de vers de terre (H' = 0,97) alors que les friches ne présentent aucune diversité.

Earthworm communities in organic and conventional coffee cultivation

The objective of this work was to evaluate the effect of organic and conventional coffee crops on biomass, population density and diversity of earthworms, in Lerroville, district of Londrina County, Paraná state, Brazil. Earthworm communities were sampled in three areas with organic coffee cultivation (CO1, CO2 and CO3), two with conventional coffee (CC1 and CC2), and a native forest fragment (MT). The soil of the areas CO1, CC1, and MT was classified as Nitossolo Vermelho (Rhodic Kandiudox), while CO2, CO3, and CC2 were on Latossolo Vermelho (Rhodic Hapludox). Eight samples were taken in each area on two occasions, winter and summer, using the Tropical Soil Biology and Fertility (TSBF) method in the 0-20 cm soil layer. The earthworms were handsorted and preserved in 4% formaldehyde, and were later weighed, counted and identified. The highest earthworm biomass, both in winter and summer, occurred in the CO3 area. For population density, the higher numbers of individuals were found in CO1 and CO3. The highest number of species was identified in the organic cultivation. The adoption of organic practices in coffee cultivation favored the diversity, density and biomass of earthworm communities.

The earthworm fauna of regenerating forests and anthropogenic habitats in the coastal region of Paraná

The aim of this study was to evaluate abundance, biomass and diversity of earthworms in the southern coast region of the Mata Atlântica biodiversity hotspot. A total of 51 study sites in pastures, banana monocultures, mixed agroforestry systems, secondary forests in succession and old-growth forests near the coast of Paraná, Brazil, were evaluated. Each site was sampled once. Species richness of the earthworms was generally low and varied little between sites. At all sites except for one, the peregrine species Pontoscolex corethrurus (Glossoscolecidae) strongly dominated. Three other peregrine species, Amynthas corticis, Amynthas gracilis (Megascolecidae) and Ocnerodrilus occidentalis (Ocnerodrilidae), were frequent in moist sites. No autochthonous species were found. Abundance and biomass of earthworms varied strongly within and between sites (0-338 individuals m-2, 0-96 g m-2 fresh weight). Pastures had significantly lower abundance than all other sites. The forest sites had similar earthworm abundance and biomass, with a tendency to be higher in younger succession stages. The coastal plain region has been strongly altered by human activities. Reasons for the lack of any autochthonous species and the dominance of one peregrine species require further investigation.

Earthworms from Mato Grosso, Brazil, and new records of species from the state

The objective of this work was to undertake a qualitative assessment of earthworm diversity in areas under human influence, in a region of Cerrado-Pantanal-Amazon rainforest transition, in the state of Mato Grosso, Brazil. The earthworms were collected in the municipalities of Barra do Bugres and Arenápolis, and were studied together with species previously identified from other municipalities. Seventeen municipalities, at 29 sampling points of Mato Grosso State, have been sampled. Seven species of earthworms were collected and identified in Barra do Bugres: Goiascolex vanzolinii, Pontoscolex (Pontoscolex) corethrurus, Opisthodrillus borellii borellii, Opisthodrillus sp., Dichogaster (Diplothecodrilus) gracilis, Dichogaster sp. and a species of the Criodrilidae family. Four species of earthworms were identified in Arenápolis: Pontoscolex (Pontoscolex) corethrurus, Dichogaster (Diplothecodrilus) gracilis, Dichogaster (Diplothecodrilus) affinis and Dichogaster sp. In total, 32 earthworm species/subspecies are known from Mato Grosso, 22 native and 10 exotic.

Response of earthworm communities to soil disturbance: Fractal dimension of soil and species’ rank-abundance curves

Soil structure degradation and its relationship with soil fauna communities is a crucial issue in soil management. The aim of this work is to analyze soil fractal dimensions and the earthworm community structure along a perturbation gradient in a Typic Argiudoll soil with different combinations of annual crops and pastures. Samples were taken in four sites: a natural grassland (NAT) without cultivation for 30 years, and three pastures of 1–3 years (P1, P2, P3). Five undisturbed soil blocks were taken per site in order to evaluate soil structural complexity. Two fractal dimensions were measured on images of polished sections of the blocks: the mass fractal dimension of pores ( Dmp), and the mass fractal dimension of soil solid complement ( Dms). Biomass, number and species composition of earthworm communities were assessed by hand-sorting 15 samples of 25 cm × 25 cm × 20 cm on each site. Species rank vs. abundance distribution were fitted to geometric series and broken stick models. Shannon index and expected species number by rarefaction ( E( S)) were calculated. Both soil solid and pore space evaluated may be considered as fractals in all sites analyzed. We found that the fractal dimension of pores was significantly ( p < 0.03) higher for NAT and P3 (1.63 ± 0.03 and 1.62 ± 0.02, respectively) than for P1 (1.43 ± 0.05). Species richness was P1: 3, P2: 7, P3: 7, NAT: 9. Species abundance vs. rank curves shows better fit to the geometric series model in all sites. We found the highest values of Dmp in sites with the higher diversity and species richness of earthworms, suggesting a trend between the observed biological activity and the fractal dimension of the habitat.

A six year study of earthworm (Lumbricidae) populations in pasture woodland in southern England shows their responses to soil temperature and soil moisture

There are very few studies on the effects of temporal changes in soil properties on ecosystem engineers in UK soils. This study addresses this lack by presenting earthworm diversity data from a six-year seasonality study comprising 72 monthly samples from the litter and soil of pasture woodland in the New Forest, southern England. These data were analysed in the context of soil moisture and soil temperature, key factors affecting earthworm abundance, and factors likely to be strongly affected by future climate change. The data for the whole period were analysed using non-parametric regression and an additive model used to separate within-year and between-year effects. Seasonal patterns are present for all the common species, generally with a maximum in March and a minimum in September. A majority of the five commonest species show a strong decline in abundance during the two extremely dry periods (2002–2003 and 2006). In sharp contrast, the same species showed a relative increase during the very wet summer and autumn of 2007. There was, however, no significant overall trend in either the climate data or the earthworm species data. The epigeic species, Dendrobaena octaedra, showed the largest decline in the driest months which caused a crash to the point where there were no adults sampled during the four dry summer months of 2003. A second congeneric species, Dendrobaena attemsi, also epigeic, appears to have invaded the woodland during the six year period and is increasing rapidly in abundance. This may indicate the start of a shift in the distribution of the two species, as D. octaedra generally has a northern European distribution and is frost-tolerant, while D. attemsi has a southern European distribution and is more drought-tolerant. In contrast, the very wet summer of 2007 seems to have damped the usual periodic seasonal oscillations in earthworm numbers. Endogeic worm species do not show the D. octaedra seasonal pattern as obviously, probably because these species are able to move more freely through the soil and because they are able to aestivate. These changes are likely to be due to a combination of human movement of earthworms (e.g. D. attemsi) and variations in local climate.

Species diversity and distributions of microdrile earthworms (Annelida, Clitellata, Enchytraeidae) from South America

A comprehensive biodiversity database of Enchytraeidae produced 66 nominal species reported to date from South America (Achaeta, 6 species; Buchholzia, 1; Cognettia, 1; Enchytraeus, 3; Fridericia, 5; Grania, 1; Guaranidrilus, 10; Hemienchytraeus, 12; Henlea, 2; Lumbricillus, 7; Marionina, 12; Stephensoniella, 1; Timmodrilus, 1; Tupidrilus, 4). Almost 76% of this fauna (50 species) is endemic to the South American continent. The remaining 16 species are more or less largely distributed. Detailed South American occurrences are provided. This is the first reassessment of South American enchytraeids in 27 years. The group is conspicuoulsy absent from the northeast region of Brazil. Enchytraeidae are microdrile earthworms, representing the sister group of the Crassiclitellata, or megadrile earthworms. This relationship is supported by molecular phylogenies, ontogenetic transformations, ecological evidence, and several morphological synapomorphies (dorsal pores, contractil dorsal vessel, lateral position of dorsal chaetal bundles, and shape of chaetae).

Earthworm communities a bioindicator of arable land management practices: A case study in semiarid region of India

Abstract The abundances and activities of earthworms in arable lands depend strongly on management practices and; therefore earthworm can act as a potential bioindicator of land use practices. In this study earthworm diversity and abundances was measured in three differently managed agro-ecosystems i.e. conventional, integrated and organic, in some sites of northern semiarid region of India. The maximal numbers of earthworm occurrence were in integrated farming system (100%, all studied sites showed the presence) followed by organically managed (70%) and conventional (18.9%) agro-ecosystems. A total of six species belonging to four different families were identified during this survey and all recorded earthworm species were present in organically managed agro-ecosystems, while integrated and conventional arable lands exhibited only three earthworm species. The abundance of earthworms in arable system was also directly related to the management practices. The values of ecological indices e.g. Shannon diversity (H′), species dominance (C), the species richness (S) and evenness (E) indicated the anthropogenic pressure on earthworm communities in arable lands of northern India.

Diversity and abundance of earthworms across an agricultural land-use intensity gradient

Understanding how communities of important soil invertebrates vary with land use may lead to the development of more sustainable land-use strategies. We assessed the abundance and species composition of earthworm communities across six replicated long-term experimental ecosystems that span a gradient in agricultural land-use intensity. The experimental systems include a conventional row-crop agricultural system, two lower-intensity row-crop systems (no-till and tilled organic input), an early successional old-field system, a 40–60 years old coniferous forest plantation, and an old-growth deciduous forest system. Earthworm populations varied among systems; they were lowest in the most intensively managed row-crop system (107 m −2) and coniferous forest (160 m −2); intermediate in the old-field (273 m −2), no-till (328 m −2) and tilled organic (344 m −2) cropping systems; and highest in the old-growth deciduous forest system (701 m −2). Juvenile Aporrectodea species were the most common earthworms encountered in intensively managed systems; other species made up a larger proportion of the community in less intensively managed systems. Earthworm community biomass and species richness also varied and were lowest in the conventional row-crop system and greatest in the old-growth forest system. These results suggest that both land-use intensity and land-use type are strong drivers of the abundance and composition of earthworm communities in agricultural ecosystems.

Earthworm ( Lumbricidae) diversity in the Central Balkans: An evaluation of their conservation status

In this paper we summarize the current knowledge on earthworm diversity in the central part of the Balkans, in the State of Serbia. Up to now, 71 species and 8 subspecies, belonging to 18 genera, are known from investigated territory. Our aim was to produce a single priority list for earthworm conservation, particularly as the Balkan countries did not have their own Red Lists for earthworms and none of the species had a legally protected status. The list underlines the diversity of earthworms, zoogeographical position as well as category of threat. The analysis based on the IUCN (2001) Red List Categories shows that 17 of 79 taxa are Critically Endangered (5 species are serious Critically Endangered, but 12 species are only suspect for the Critically Endangered category), 9 species are Endangered and 14 species are Vulnerable. Serious candidates for their inclusion in CR category within the IUCN (2001) Red List are: Cernosvitovia biserialis, Dendrobaena kozuvensis, Lumbricus improvisus, Serbiona kosowensis montenegrina and Serbiona serbica. Of all registered earthworms, 34 taxa (43.1%) were identified only as endemic species. Unfortunately, most of the high-priority species are endemic (23 taxa). The position of the Central Balkans contributes to the great biodiversity of earthworms on its territory, but the fact that nearly 36% of its lumbricids are threatened is a strong signal that action is required.

Earthworm populations sampled using collection methods in atlantic forests with Araucaria angustifolia

Araucaria angustifolia, also known as the Paraná Pine is an endangered tree species in Brazil and little is known of the diversity of soil invertebrates inhabiting these forests. Therefore, the present study was set up to evaluate the biomass and diversity of earthworms in natural and reforested Araucaria plots, impacted or not by fire, and to identify the most efficient earthworm collection method. Four study areas included: native forest with Araucaria (NF); Araucaria reforestation (R); Araucaria reforestation submitted to an accidental fire (RF); and native grass pasture with native Araucaria and submitted to an intense accidental fire (NPF). Five soil samples containing the earthworm community were taken in a 0.3 ha area in each of the forest sites, close to five Araucaria trees selected at random. Three collection methods were tested: application of dilute Formol (0.5%) to the soil surface, handsorting of small (25 &lt;FONT FACE=Symbol&gt;´&lt;/FONT&gt; 25 cm) or large (40&lt;FONT FACE=Symbol&gt;´&lt;/FONT&gt; 40 cm) monoliths. Five earthworm species were found: the native Glossoscolex sp.1, Glossoscolex sp.2, Glossoscolex bondari and Urobenus brasiliensis (Glossoscolecidae), and the exotic Amynthas corticis (Megascolecidae). Formol was more efficient for collecting A. corticis, found in much higher abundance and biomass in NF than in the other areas. Larger handsorted samples were more efficient for capturing Glossoscolex species, mainly present in RF and NPF. For adequate characterization of earthworm abundance and biomass in these Araucaria forests, both the Formol and the larger monolith methods are recommended.

Can earthworms be used as bio-indicators of land-use perturbations in semi-deciduous forest?

The potential of tropical earthworms as bio-indicators of forest degradation by human-induced activities was assessed at a landscape level in the Ivory Coast. The study site covered 400 ha and was characterized by a set of land-use types along a gradient of perturbation from semi-deciduous forest, through reforestation, fallow systems to cultivated annual crops. Samples were taken on a grid at each sampling point and earthworms were hand-sorted from a 25 × 25 × 30-cm soil monolith. Results showed a potential increase in relative populations (number: +53.1%, biomass: +94.8%) of species in the earthworm communities following forest conversion. Furthermore, the impact of land-use change was higher in relation to land-use intensification in terms of earthworm populations and diversity in intermediate-disturbed systems (Multispecies plantations, old fallows). Earthworm diversity was the most sensitive response to land-use change. The species Dichogaster saliens Beddard 1893, Hyperiodrilus africanus Beddard 1891, Millsonia omodeoi Sims 1986, Dichogaster baeri Sciacchitano 1952, Dichogaster ehrhardti Michaelsen 1898, Agastrodrilus sp., Stuhlmannia palustris Omodeo and Vaillaud 1967 and, to some extent, Millsonia sp. appeared to be most sensitive to land-use change. More field and laboratory investigations are needed to find out the most efficient species to be used in bio-monitoring programmes aimed at preventing ecosystem degradation due to anthropogenic activities in the forest areas of Ivory Coast.

Seasonal changes in earthworm diversity and community structure in Central Côte d’Ivoire

This study assessed the impact of seasonal variation in the structure and diversity of earthworm communities of a savanna protected for 27 years in the central region of Côte d'Ivoire. Earthworm species were sampled in 1995 at monthly intervals from January to December on a 95 × 50 m experimental plot, using direct hand-sorting techniques. Each month, 10 monoliths of 1 m 2 × 40 cm were randomly selected from a stratified bloc design. Ten earthworm species were collected over the study period. Chuniodrilus zielae from the Eudrilidae family was by far, the most important earthworm species in term of abundance. Although earthworm diversity varied significantly, the effect of seasonal variation was unclear. Sampling efficiency of species richness varied from 80% to 100% regardless of the rainfall variation. On a seasonal time scale the C-score was lower (0.139) than expected (0.154), showing that earthworm communities exhibit a random pattern of organization. There was no evidence of non-random seasonal niche overlap because the Czechanowski index (0.50) was not significantly larger than expected (0.49).

Dispersal and clonal diversity of North-European parthenogenetic earthworms

At least 15 earthworm species are known to reproduce parthenogenetically. Most of these retain meiosis but the chromosome set is duplicated before meiosis; alternatively there is mitosis instead of meiosis. In both cases the offspring are genetic copies of the parent worm. Parthenogens are always polyploid. Parthenogenesis is associated with a dispersal advantage: a single propagule suffices to establish a new population. We have studied the clone pool structure and dispersal of ecologically dissimilar polyploid parthenogenetic lumbricids in northern Europe using enzyme electrophoresis. The anthropochorous Octolasion cyaneum has a very low number of clones in populations that are located far away from each other. The opposite is the eurytopic Dendrobaena octaedra that has a wide array of clones in each population. The ripicolous Eiseniella tetraedra disperses with flowing water and possibly also through zoochory. On subarctic North-European mountains its clone pool decreases with increasing elevation. At the top there are a few but persistent clones. Small brooks carry propagules downstream, so that at the mouths of brooks clone pools are more diverse than higher up; again larger rivers carry clones downstream. Clone dispersal is relatively free in a freely flowing river, while dams stop propagules in harnessed rivers. The mouths of rivers have high E. tetraedra clone diversity. Clones disperse from these clone centers to islands formed through land uplift along the northern Baltic Sea. The annual turnover of clones is high on these islands. A survey of epigeic and endogeic parthenogens on the Aland islands which serve as stepping stones between Estonia, Finland and Sweden shows an invasion route of clones across the Baltic Sea. Anthropochory (Aporrectodea rosea and Octolasion cyaneum) and hydrochory (E.tetraedra and Dendrobaena octaedra) seem to play important roles in the clone pool formation on the Aland islands. Quite recently an exotic parthenogen Dichogaster bolaui has found a curious habitat in human settlements viz., the sewer pipe system. Many clonal earthworms show significant morphological and morphometric diversity in and between sample localities but we have failed to associate this variation with the clonal variability. It seems that local factors modify the morphometrics and morphology ultimately determined by the genotype of parthenogenetic earthworms.

Influence of agricultural intensification on the earthworm community in arable farmland in the North China Plain

Two field experiments had been conducted in Huantai County, Shandong Province, east of China, with an effort to understand the impact of agricultural intensification on earthworm diversity and population density. Seven species of earthworms were identified in the two experiments. Average earthworm populations in the higher fertility soil (experiment B, 1.83% organic matter) were relatively abundant, with a population density of 105 indiv./m 2 and biomass of 57 g/m 2. Aporrectae trapezoids was the most dominant species. In the lower fertility soils (experiment A, 1.43% organic matter) the population density was only 51 indiv./m 2 and the average biomass was 30 g/m 2. Drawida gisti was the most dominant species. For both the experiments A and B, organic fertilizer (OF) and crop straw return increased earthworm abundance. The impact of chemical fertilizer (CF) on the earthworm population was found to depend on the amount of organic input. In experiment B, the earthworm biomass decreased when only winter wheat ( Triticum aestivum) straw was input at three CF application levels. However, while both winter wheat straw (WS) and corn ( Zea mays) stalk returned, there was no negative correlation between CF and earthworm density and biomass.

CHANGES IN HARDWOOD FOREST UNDERSTORY PLANT COMMUNITIES IN RESPONSE TO EUROPEAN EARTHWORM INVASIONS

European earthworms are colonizing earthworm-free northern hardwood forests across North America. Leading edges of earthworm invasion provide an opportunity to investigate the response of understory plant communities to earthworm invasion and whether the species composition of the earthworm community influences that response. Four sugar maple-dominated forest sites with active earthworm invasions were identified in the Chippewa National Forest in north central Minnesota, USA. In each site, we established a 30 x 150 m sample grid that spanned a visible leading edge of earthworm invasion and sampled earthworm populations and understory vegetation over four years. Across leading edges of earthworm invasion, increasing total earthworm biomass was associated with decreasing diversity and abundance of herbaceous plants in two of four study sites, and the abundance and density of tree seedlings decreased in three of four study sites. Sample points with the most diverse earthworm species assemblage, independent of biomass, had the lowest plant diversity. Changes in understory plant community composition were most affected by increasing biomass of the earthworm species Lumbricus rubellus. Where L. rubellus was absent there was a diverse community of native herbaceous plants, but where L. rubellus biomass reached its maximum, the herbaceous-plant community was dominated by Carex pensylvanica and Arisaema triphyllum and, in some cases, was completely absent. Evidence from these forest sites suggests that earthworm invasion can lead to dramatic changes in the understory community and that the nature of these changes is influenced by the species composition of the invading earthworm community.

Changes in diversity, protein content, and amino acid composition of earthworms from a paddy soil under different long-term fertilizations in the Tai Lake Region, China

Abstract Influence of the agricultural management practices on soil quality and the ecosystem functioning has been an increasing concern in soil science and ecology with sustainable agriculture. This study deals with the changes of soil earthworm communityfrom a paddy soil under different long-term fertilizations. The soil earthworms were collected and counted from different fertilizer treated plots in the field after the rape harvest in May 2004, and their taxonomic groups were determined under a binocular stereoscope at the laboratory. The body of the earthworm ( Metaphire californica) was crushed by a cell crusher to collect protein, and the protein molecules with different sizes were analyzed by electrophoresis. Furthermore, the Metaphire californica collected was hydrolyzed and the aliquots were subject to an amino acid auto-analyzer. The results showed that totally seven species of earthworms were recognized in the paddy field with the number varying with different fertilization treatments. The structure of earthworm communities was dramatically affected by the fertilization practice. Under chemical fertilization only, both the number of earthworm species and the quantity of individuals were significantly smaller than those under other treatments, or even than those under no fertilization. Furthermore, there was an obvious decrease in the total amino acid and the contents of most individual amino acids of Metaphire californica under chemical fertilization only, compared with those under the combined fertilization of chemical and organic fertilizers. Although chemical fertilizers in combination with rice straw return increased earthworm amino acid content, long-term pig manure application tended to increase earthworm protein content. As a molecular footprint, long-term chemical fertilization caused a reduction in the content of protein with MW less than 25 kd, but a significant increase in that of protein with molecule size around 33 kd. Our study demonstrated that different fertilizations affected not only earthworm population but also diversity and richness in the paddy soil after 16 years of treatment, and that long-term chemical fertilization may impact the soil animal community and, thus, influence the paddy ecosystem functioning for yield stability. This study implicated that not only the community structure but also the amino acid metabolism for life functioning of earthworms in cropland soils may pose significant responses to the agricultural management practices.

Soil biota indicators for monitoring the Estonian agri-environmental programme

The mandatory implementation of agri-environmental programmes (AEP) during the accession to the EU was a major policy development in the countries of Central and Eastern Europe. In Estonia the development of the AEP began in 1997 and the implementation of the AEP in pilot areas was launched in 2001. By this time, evaluation and monitoring methodologies of AEP had been elaborated. This paper summarises the Estonian AEP applied in 2001–2003 and presents selected indicators of biodiversity. The main focus is on the analysis of selected indicators of soil biota. Soil bioindicators (abundance, diversity, and ecological composition of earthworm communities and hydrolytical activity of the microbial community) were measured in 2001 and 2002. Two pilot areas of the AEP (Palamuse, representing a municipality with intensive agriculture, and Kihelkonna–Lümanda, representing extensive agriculture) and two reference areas where the AEP was not implemented (Mustjala and Saare municipalities) were investigated. Ten farms in both pilot areas and five in both reference areas were studied. There were differences in the abundance and number of earthworm species between Palamuse (intensive agriculture) and Saaremaa (extensive) pilot areas, but these were not statistically significant. However, the differences in the hydrolytical activity of the microbial community between Palamuse and Saaremaa pilot areas were statistically significant ( p < 0.05). It is concluded that soil bioindicators are suitable for monitoring human pressure as well as the effects of AEPs. AEPs may increase the abundance and diversity of earthworms, decrease the dominance of A. caliginosa , and increase the activity of the microbial community.

Plant influences on native and exotic earthworms during secondary succession in old tropical pastures

Land-use changes can drastically alter earthworm communities. Native species are often lost and few exotic species, such as Pontoscolex corethrurus, rapidly prevail when tropical forests are converted to pastures. However, this process can be reversed when forests recover from abandoned pastures through secondary succession. We hypothesized (1) that the formation of forest floor mass during secondary succession in pastures promotes the recovery of native, anecic earthworms and (2) that the shift from grass vegetation in pastures to woody plants in secondary forests decreases the abundance and biomass of the exotic, endogeic P. corethrurus. To test the first hypothesis, we developed a litter manipulation experiment by removing and adding plant litter in plots of mature secondary forests in the Cayey Mountains, Puerto Rico. To test the second hypothesis we performed a greenhouse experiment to examine the influence of a pasture grass species Axonopus compressus and a dominating woody species Miconia prasina of the secondary forests on the number and biomass of the earthworm P. corethrurus. We found in the litter manipulation experiment that earthworm diversity, density and fresh weight were not affected by litter input. However, in the greenhouse experiment, A. compressus increased the number and biomass of P. corethrurus, whereas M. prasina decreased the exotic, endogeic earthworm. Our results suggest that the quantity of litter does not promote rapid changes (<1 year) in native, anecic earthworm diversity, and that the exotic, endogeic P. corethrurus is favored by grass A. compressus compared to the woody plant M. prasina. The shift in vegetation from grass to woody plants promotes the decrease in the density and biomass of the exotic, endogeic P. corethrurus during secondary succession in old tropical pastures.

Ring-testing and field-validation of a terrestrial model ecosystem (TME)--an instrument for testing potentially harmful substances: effects of carbendazim on earthworms.

The effects of the fungicide carbendazim (applied in the formulation Derosal) on earthworms (Lumbricidae) was determined in Terrestrial Model Ecosystem (TME) tests and field-validation studies. TMEs consisted of intact soil columns (diameter 17.5 cm; length 40 cm) taken from a grassland or, in one case, from an arable site. The TMEs were taken from the same site where the respective field-validation study was performed. The tests were performed in Amsterdam (The Netherlands), Bangor (Wales, UK), Coimbra (Portugal) and Flörsheim (Germany). The sites selected had an earthworm coenosis representative of the different land use types and regions. In addition, the differences between the coenosis found in the TMEs and the respective field sites were in general low. A high variability was found between the replicate samples, which reduces the probability of determining significant differences by the statistical evaluation of the data. Similar effects of the chemical treatment were observed on abundance as well as on biomass. Effects were most pronounced 16 weeks after application of the test chemical. The observed effects on earthworm abundance and biomass did not differ between the TME tests and the respective field-validation studies. Effects on earthworm diversity were difficult to assess since the number of individuals per species was low in general. However, the genus Lumbricus and in particular L. terrestris and L. rubellus seemed to be more affected by the chemical treatment than others. NOEC and EC50-values derived from the TME pre-test, the TME ring-test and the field-validation study indicate that the TMEs of the different partners delivered comparable results although different soils were used. Due to the high variability NOECs could often not be determined. The EC50-values for the effect of carbendazim on earthworm abundance ranged between 2.04 and 48.8 kg a.i./ha (2.71-65.2 mg/kg soil) and on earthworm biomass from 1.02 to 34.6 kg a.i./ha (1.36-46.0 mg/kg soil). These results indicate that the abundance and biomass of earthworms are suitable endpoints in ecotoxicological studies with TMEs.