Weight response to the soil water potential of the earthworm Aporrectodea longa

Summary To assess the ability of endogeic earthworms to tolerate variations in soil water potential, groups of these worms were subjected to different, constant levels of soil water suction () over a period of 17 days. At water suctions varying from 0.3 kPa (pF 0.5) to 1990 kPa (pF 4.3), the earthworms showed no physiological ability to a maintain constant internal water content as assessed by the fresh weight. The relationship between weight loss and the increase in water, suction was modelled and the following critical thresholds were identified: <60 kPa did not affect earthworm weight; >620 kPa led to diapause; between these two values, earthworm weight was closely governed by the variation in . At the intermediate suction of 167 kPa, the exchange of water between the earthworms and the soil was at a maximum, and this value is therefore proposed as the level at which the diapause is induced. These modelled values were the diapause is induced. These modelled values were compared with those obtained under field conditions.     

Earthworm composition,diversity and biomass under three land use systems in south-eastern Australia

In south-eastern Australia, strips of planted native trees and shrubs (shelterbelts) are frequently established to restore ecosystem services altered by agriculture. Despite their wide use, little is known about the effects of establishing shelterbelts on soil macro invertebrates, especially earthworms, which are of major importance in soil processes. We assessed earthworm composition, diversity and biomass in three land use systems: native shelterbelts dominated by Acacia and Eucalyptus species, agricultural pastures and native remnant woodland fragments dominated by Eucalyptus blakelyi and/or Eucalyptus melliodora. Earthworm communities differed significantly among systems, with abundance, biomass and diversity greatest under pasture. Within shelterbelts we saw a shift from high earthworm biomass and density to low with increasing time after establishment. Soil edaphic variables did not correlate strongly with earthworm biomass or density, but were correlated with earthworm community composition. Overall the introduction of native woody vegetation was associated with a decline in density and biomass of earthworms, including a decrease in the relative abundance of exotic species. As such shelterbelts can be used to promote native earthworm relative abundance, which may be important for local diversity, soil function and landscape connectivity.     

Stable C and N isotope values of selected components of a tropical australian sugarcane ecosystem

The ¹³C and ¹⁵N values of sugarcane plant tissues, decomposing harvest residues, soil and the casts and body tissues of the earthwormPontoscolex corethrurus were determined. Little variation in ¹³C values was found between plant parts. The ¹³C values of the decomposing harvest residues declined and became more variable after 148 days of exposure in the field. In the decomposing residues, ¹³C values of the neutral detergent fibre fraction were similar to those of the whole tissues while those of the proximate lignin were more negative. The ¹⁵N values of the residues also declined over time after a short initial delay.P. corethrurus populations are more intimately associated with the roots of sugarcane than with the bulk soil. Tissue ¹³C values suggest that the earthworm diet is similar to or more enriched in¹³C than sugarcane tissues and is substantially more enriched than the soil C. Earthworm tissues have similar levels of¹⁵N enrichment to both the soil and plant tissues. These data are consistent with the hypothesis that this earthworm derives much of its assimilated C relatively directly from organic matter associated with the roots and decomposing harvest residues.     

Impact of soil stockpiling and mining rehabilitation on earthworm communities

As key ‘ecosystem engineers’, earthworms improve mineralization of organic matter, plant growth, soil quality, and are an important component of many terrestrial food webs. Under appropriate conditions, they are therefore likely to accelerate the restoration of soil ecosystem function after mining.Conserving naturally occurring populations and facilitating their recolonisation appears as the most efficient way to increase earthworms’ overall effect. The impact of mining activities and restoration measures on New Zealand endemic earthworm communities was tested. Earthworm biomass and diversity were compared in four different habitat types.Mining activities, not surprisingly, are shown here to have a detrimental impact on earthworm communities. Soil stockpiling induces anaerobic conditions at and below a depth of 1 m, where earthworms do not survive. The use of stockpiled soil for vegetation replanting therefore leads to low diversity and low abundance of earthworms. An alternative restoration technique consisting in transferring vegetation and soil units (the vegetation direct transfer) was efficient in preserving earthworm populations with earthworm biomass and diversity not significantly different from those observed in undisturbed areas. Based on these results, we recommend vegetation direct transfer (VDT) to be prioritised whenever it is logistically and economically feasible. When VDT is not applicable, low stockpiles should be prioritised as they will comprise a higher proportion of good quality soil (at the surface) and a lower proportion of anaerobic and compacted soil (below 1 m depth at the studied site).     

A chromatographic approach to the taxonomy ofVicia L.

Summary Paper chromatography was applied to investigate the distribution of flavonoids plus other not identified phenols in ten species ofVicia.Considerable biochemical differences were found between as well as within species. The extract ofV. cordata produced a chromatogram substantially different from other taxa of theV. sativa aggregate which confirms its separation as species. The similarity in flavonoids betweenV. villosa andV. dasycarpa supports the view of considering the latter as a subspecies of the former. Similar comments are made on the other species investigated.Cluster analysis may be useful for studying species relationships. It suggests the existence of a parallel between evolutionary advancement and degree of diversification. The results of this small survey would encourage the use of flavonoids and other secondary products for improving the existing classification of the genus.

---

Ein chromatographischer Beitrag zur Taxonomie vonVicia L.

Zusammenfassung Papierchromatographie wurde zur Analyse des Vorkommens von Flavonoiden und weiteren nicht identifizierten phenolischen Verbindungen in 10Vicia-Arten genutzt.Betiächtliche biochemische Unterschiede wurden sowohl zwischen als auch innerhalb von Arten ermittelt. Der Extrakt vonV. cordata ergab ein wesentlich von anderen Taxa desV. sativa-Aggregats abweichendes Chromatogramm, das die Abgliederung dieser Sippe als eigene Art bestätigte. Andererseits stützt die Ähnlichkeit der Flavonoide vonV. villosa andV. dasycarpa deren Zusammenfassung als 2 Unterarten einer Art. Ähnliche Kommentare waren bei anderen untersuchten Arten möglich.Die Cluster-Analyse konnte erfolgreich zur Einschätzung der Verwandtschaft zwischen den Arten herangezogen werden. Mit ihrer Hilfe ergab sich eine Parallele zwischen dem Grad abstammungsgeschichtlicher Ableitung und dem Ausmaß der Differenzierung.Die Ergebnisse dieser ersten Übersicht ermutigen zur weiteren Verwendung von Flavonoiden und anderen sekundären Pflanzenstoffen bei der Optimierung der Klassifikation der Gattung.

---

Vicia L.

10 Vicia. , . V. cordata , V. sativa, ¶rt; . , V. villosa V. dasycarpa . . . . .

     

Nitrification and denitrification activities of zinc-treated soils worked by the earthworm<Emphasis Type="Italic"> Pheretima</Emphasis> sp.

Little information is available on the roles of earthworms in N transformation and biological activities in heavy metal-contaminated soils. The purpose of the present paper is to examine the effects of earthworm on nitrifying and denitrifying enzyme activities of Zn-treated soils. ZnCl₂ solution was added to soils at rates ranging from 0 to 400 mg Zn kg^–1 and was allowed to fractionate and stabilize for 60 days. The Zn-tolerant earthworm Pheretima sp., which had been previously screened, was then introduced into Zn-treated soils and allowed to work for 40 days. Original soils without the addition of Zn and introduction of earthworms but incubated under the same conditions were used as controls. Zn-treated soils without the introduction of earthworms were also used as controls. Results showed that earthworm activity increased both nitrifying and denitrifying enzyme activities of the soils. These beneficial effects of earthworms were particularly evident in the treatments where Zn had an adverse effect. Zn added at a rate 200 mg Zn kg^–1 generally had a stimulating effect on the enzyme activities measured. However, Zn added at a rate >200 mg Zn kg^–1 had an adverse effect on nitrifying and denitrifying enzyme activities, which could be alleviated or even completely eliminated by earthworm activities.     

Recolonization of methyl-bromide sterilized soils by plant and soil nematodes over 52 months

Recolonization of soils by organisms is dependent not only on biological factors but also on site factors including soil and vegetation. The total nematode populations in soil sterilized 52 months earlier with methyl bromide ranged from 77 to 123% of those in untreated soil; both vegetation and rainfall appear to have been important factors in the recolonization. In a high-rainfall pasture the dominant plant-feeding nematode Helicotylenchus did not recolonize and was replaced by Paratylenchus. Under high rainfall, Iotonchus failed to recolonize either pasture or forest, but Clarkus recolonized well. While indices such as the maturity index, the summed maturity index, PPI, the ratio of fungal: bacterial feeding nematodes, species richness, the Shannon-Weaver index, and indices of evenness, dominance, and diversity showed various effects, none gave consistent trends; rainfall and vegetation probably exerted too much influence. In the light of trends in our data, in data for other ecosystems, and the reality of r-K strategies in animals, it may not be reasonable to expect a global nematode index of soil health or ecosystem condition. While a nematode index may be useful in local or regional studies, research efforts may be better directed towards elucidating key populations of nematodes for investigating the impact of particular land management practices on ecosystem sustainability.     

Significance of developmental stages in the coexistence of three species of Mononchoidea (Nematoda) in a pasture soil

Summary Populations of each developmental stage of three mononchid species (Clarkus, Cobbonchus, Iotonchus) under grazed pasture were estimated in the presence and absence of the earthworm Aporrectodea caliginosa. All stages of all species had signs of prey in their gut. Introduction of earthworms changed the abundance of the species from 158000, 84000 and 2400/m² to 43 000, 5000 and 41300/m², but total biomass remained relatively unchanged at 288000 g/m². The larger Iotonchus was more abundant in the soil with earthworms and improved texture. The length ratios between the stages of the three species are 1.225, 1.235 and 1.395, with the overall mean of 1.285 close to the value for the Dyar-Hutchinson rule. Other analyses of population separation are made. Given the unequal abundance of the various stages, the species successfully coexist and exploit a wide resource. Predation by such nematodes on bacterial-feeding nematodes may influence bacterial grazing and thus nutrient cycling.     

Does the influence of earthworms on water infiltration, nitrogen leaching and soil respiration depend on the initial soil bulk density? A mesocosm experiment with the endogeic species Metaphire posthuma

Soil compaction has a negative impact on both earthworm abundance and diversity. Recent studies, however, suggest that earthworm cast properties are not influenced by the initial soil bulk density. With time, earthworms could therefore transform soils with different bulk densities into a soil with the same physical state and thus with a similar ecological functioning. This study aimed to test this hypothesis in two laboratory incubation experiments. First, we measured the influence of soil bulk density (1.1 or 1.4?g?cm^?3) on the production of cast by the endogeic earthworm species Metaphire posthuma. In a second experiment, we investigated the effect of M. posthuma on water infiltration, NH ₄ ⁺ , and NO ₃ ^? leaching and soil respiration at the same two soil bulk densities. Although initially higher, earthworm casting activity in soil at 1.4?g?cm^?3 decreased until it reached the same level of activity as earthworms in soil at 1.1?g?cm^?3. This behavioral plasticity led to a transformation of compacted and loose soils, with their own functioning, to a third and similar state with similar hydraulic conductivity, nitrogen leaching, and soil respiration. The consequences for soil organization and soil functioning are discussed.     

Uptake and toxicity of copper and zinc for the African earthworm,Eudrilus eugeniae (Oligochaeta)

Growth rate change in earthworms is considered to be a suitable endpoint when determining sublethal effects. In this study we evaluated growth and maturation in the vermicomposting earthworm speciesEudrilus eugeniae as marker of sublethal toxicity of copper and zinc. We also compared routes of uptake. Apart from exposing worms experimentally for 73 days to contaminated food, a series of contact filter paper tests was also performed to determine LD₅₀ for copper and zinc. Both copper and zinc at sublethal concentrations affected growth and maturation in worms exposed to contaminated food. These worms had a copper content of 34.5 g g^–1 after 73 days and a zinc content of 184.9 g g^–1, showing a differential uptake. Copper was more toxic than zinc. Also in the contact test worms did take up more zinc than copper and the LD₅₀ (48 h) for copper was 0.011 mg cm^–2 and for zinc 0.066 mg cm^–2, which translated to body burdens of 6 g g^–1 for copper and 131 g g^–1 for zinc. Indications were that a regulatory mechanism existed for both metals. Both metals were taken up through the body wall at a relatively fast rate. This study indicated that the skin was the major route of metal uptake. This study also showed a poor relation between the two types of tests for purposes of evaluating lethality of zinc and copper.     

Influence of cadmium,copper, and pentachlorophenol on growth and sexual development of Eisenia andrei (Oligochaeta; Annelida)

Summary In the existing guidelines for earthworm toxicity testing, mortality is the only test criterion. Mortality is, however, not a very sensitive parameter, and from an ecological point of view growth and reproduction are more important for a proper risk assessment of chemicals in soil. In this study the growth and sexual development of juvenile earthworms were considered as test criteria in a standardized earthworm toxicity test. The effect of Cd, Cu, and pentachlorophenol on the growth and sexual development of juveniles of the species Eisenia andrei was studied in an artificial soil substrate. Two tests with Cd were carried out to study the effects of the mode of application of the food source (cow dung). EC₅₀ (50% effective concentration) values for the effect of Cd, Cu and pentachlorophenol on the growth of E. andrei were 33–96, >100, and >32 mg kg^-1 dry soil, respectively, and there was no observed effect at 18–32, 56, and 32 mg kg^-1 dry soil, respectively. Sexual development of the earthworms was inhibited at 10 mg Cd kg^-1 and 100 mg Cu kg^-1 dry soil, but was not affected at the highest pentachlorophenol concentration tested (32 mg kg^-1 dry soil). The results were the same whether the food was applied in a hole in the middle of the soil or mixed homogeneously through the soil.     

Extraction of humic-β-glucosidase fractions from soil

Humic compounds with -glucosidase activity were extracted from soil using tetrasodium pyrophosphate as extracting solution. Mixture of soil samples with 0.01 M pyrophosphate in a ratio of 1:5 (w/v), adjustment to pH 7.0–7.3, extraction for 18 h with reciprocating agitation, and bacteriological filtration after centrifugation were the optimum conditions for extraction of the -glucosidase complexes. Otherwise, experimental conditions for extraction indicated that the concentration and pH of pyrophosphate were the factors with the most influence on enzymatic extraction yields. The results indicated that the -glucosidase was extracellular and associated with soil humates.     

Assessment of earthworm burrowing efficiency in compacted soil with a combination of morphological and soil physical measurements

Summary Column experiments were carried out to quantify the effect of earthworms on compacted soil. The earthworms (Lumbricus terrestris) were able to burrow into soil which was artificially compacted to a pore volume as low as 40%; they may also penetrate an artificial plough pan deep in the soil. The effect of the burrowing activity of Lumbricus terrestris was quantified by measuring hydraulic conductivities and infiltration rates through the whole soil column (19 cm wide, 40 cm long). Morphological parameters, mainly the vertically projected burrow depth, were correlated with the saturated hydraulic conductivity. The amount of casts deposited by Lumbricus terrestris on the soil surface increased with the degree of soil compaction. The bulk density of casts was always less than that of the original soil.     

Introduced earthworm species exhibited unique patterns of seasonal activity and vertical distribution,and <Emphasis Type="Italic">Lumbricus terrestris</Emphasis> burrows remained usable for at least 7 years in hardwood and pine stands

It is difficult to obtain non-destructive information on the seasonal dynamics of earthworms in northern forest soils. To overcome this, we used a Rhizotron facility to compile 7 years of data on the activity of anecic (Lumbricus terrestris) and endogeic (Aporrectodea caliginosa complex) earthworms in two contrasting soil/plant community types. We hypothesized that L. terrestris burrows would be used for longer than a typical L. terrestris lifetime, and that the distribution and activity pattern of the two earthworm species would respond differently to changes in soil moisture and temperature. For 7 years we recorded earthworm distribution and activity state bi-weekly to a depth of 1.5 m, tracked L. terrestris burrows using images captured annually, and measured soil temperature and moisture. Activity and vertical distribution of earthworms was closely linked to earthworm species and soil temperature in the fall, winter and spring. Lumbricus terrestris typically remained active through the winter, whereas the A. caliginosa complex was more likely to enter an aestivation period. Activity of all earthworms decreased substantially in July and August when soil temperature was at its highest and soil moisture at its lowest for the year. Most L. terrestris burrows were used continuously and moved very little during the 7-year study, likely creating spatiotemporally stable hotspots of soil resources. The different patterns of response of these species to soil temperature and moisture suggests that endogeic earthworms are more likely than anecic earthworms to adjust activity states in response to climate change mediated shifts in soil moisture and temperature.     

Biodiversity, vegetation gradients and key biogeochemical processes in the heathland landscape

The northwest European heathland landscape with its characteristic communities of nutrient-poor and acidic soils has a high nature value, because of its locally high biodiversity and the distinct site conditions. In order to conserve and restore the heathlands, numerous rehabilitation projects have been performed, although with varying success. This is partly due to the fact that the key biogeochemical processes distinguishing the various vegetation types within the heathlands are not known in detail.Therefore, we performed a statistical survey on the main communities and their soil characteristics. In addition, we analyzed the data for key factors determining biodiversity in the heathland landscape.Data from previous studies and surveys was used to compile a dataset of 267 vegetation relevés (classified as EUNIS habitat types) with extensive soil measurements (22 parameters). A canonical discriminant analysis revealed that soil acidity explained most of the differences between the habitat types, while soil moisture content and soil fertility were less important. Acidity-related factors as Al³⁺, Al/Ca-ratio and pH were also strongly correlated to plant diversity in the majority of the habitat types, respectively, the species-rich Nardus grasslands, the Rhynchosporion communities and the species-rich Molinia meadows. In the dry heaths and over the total heathland landscape, plant diversity was negatively correlated with soil -concentrations. Only in wet heath, nutrient availability, in this case P, was the primary factor in explaining plant diversity.This study presents ranges for all major soil parameters for the studied well-developed heathland habitat types, thereby providing clear guidelines for conservation and restoration.     

Molybdenum reserves of seed,and growth and N2 fixation by Phaseolus vulgaris L.

Summary Plants grown from seed with high (1.5–7.3 g Mo seed^-1) and low (0.07–1.4 g Mo seed^-1) Mo contents were grown in the presence and absence of Mo in growth media (perlite) or in a flowing-solution culture, in a controlled environment. Neither the high (1.5 g Mo seed^-1) nor the low (0.1 g Mo seed^-1) Mo content in seed from a small-seeded genotype (BAT 1297) was able to prevent Mo deficiency (reduced shoot, root and nodule dry weight, N₂ fixation and seed production) in growth media without an external supply of Mo, whereas both the high (7.3 g Mo seed^-1) and the low (0.07 g Mo seed^-1) contents in seed were able to prevent Mo deficiency in a large-seeded genotype (Canadian Wonder). Responses to Mo treatment by the Two genotypes were inconsistent between the growth media and solution culture experiments. Seed with a large Mo content (3.5 g Mo seed^-1) from the Canadian Wonder genotype was unable to prevent Mo deficiency (reduced shoot and nodule dry weight and N₂-fixation) in a solution culture without an external source of Mo, whereas both the large (1.7 g Mo seed^-1) and the small (0.13 g Mo seed^-1) contents in seed prevented a deficiency in BAT 1297. Growing plants from seed with a small Mo content, without additional Mo, reduced the seed Mo content by 83–85% and seed production by up to 38% in both genotypes. Changes in seed size and increases in shoot, root and nodule dry weight occurred, but varied with the genotype and growth conditions. These effects were also observed in some cases where plants were grown with additional Mo, demonstrating that the amount of Mo in the seed sown can influence plant nutrition irrespective of the external Mo supply. Nodule dry weight, total N content of shoots and seed production were improved by using seed with a small Mo content (1.64–3.57 g Mo seed^-1) on acid tropical soils in Northern Zambia. Plants of both the large- and small-seeded genotypes grown from seed with a small Mo content (<1.41 g Mo seed^-1) had a smaller nodule weight, accumulated less N and produced less seed. The viability of seed with a small Mo content was lower (germination up to 50% less) than that of seed with a large Mo content.     

Vermicomposting of coffee pulp using the earthworm Eisenia fetida: Effects on C and N contents and the availability of nutrients

In Colombia, more than 1 million tons of coffee pulp are produced every year. Its transformation into compost by means of turned piles has led to a final product with poor physical and chemical characteristics and vermicomposting has been suggested as an alternative method of transforming these wastes into a useful organic fertilizer. The ability of the earthworm Eisenia fetida to transform coffee pulp into a valuable compost was evaluated. The influence of bed depth and time on different C fractions, N content and availability of nutrients was studied. The results showed that the C and N contents were not affected by the depth of the bed, whereas time affected both. An increase in the fractionation ratio, determined by calculating the C in the fraction smaller than 100 m as a percentage of C in the samples as a whole, and low values of humic-like substances were recorded during vermicomposting. After ingestion of the pulp by the earthworms, an increase in available P, Ca, and Mg but a decrease in K were detected.     

Problems of genetic erosion in Transylvania,Romania

Summary Started from the basic principles of IBP and MAB programmes, genetic resources of agricultural plant species cultivated traditionally in Transylvania have been studied. Land-races from this territory deserve special attention, as Transylvania is situated on the north-eastern border of the Mediterranian centre of diversity, between Near-East and Western Europe, has a relatively isolated position surrounded by the eastern range of the Carpathian Mountains. Traditional agriculture practiced in many of the intramountain hollows is favourable for the preservation of ancient land races and the territory is also promising in respect of spontaneous germplasm resources. In the Agrobotanical Garden of the Institute of Agronomy at Cluj-Napoca seed samples of economically important plant species — cultivated land-races and wild relatives — have been collected with the beginning of 1970. Based on this collection the threatened variability of agricultural plant species have been grouped in four major categories. Trends and peculiarities of genetic erosion acting in these groups have been exemplified with the cases ofTrifolium pratense L.,Phaseolus vulgaris L. andTriticum monococcum L.

---

Probleme der Generosion in Transylvanien, Rumänien

Zusammenfassung Ausgehend von den Grundprinzipien des IBP und MAB-Programms wurden die genetischen Ressourcen landwirtschaftlicher Pflanzenarten, die traditionell in Transylvanien angebaut werden untersucht. Landsorten aus dieser Gegend verdienen besondere Beachtung, da Transylvanien an der nordöstlichen Grenze des mediterranen Genzentrums zwischen nahem Osten und Westeuropa liegt und eine relativ isolierte Lage, umgeben von der Ostkette der Karpaten besitzt. Traditioneller Ackerbau, in vielen Gebirgsgegenden noch praktiziert, begünstigt die Erhaltung einstiger Landsorten und das Gebiet ist vielversprechend in Bezug auf das Vorkommen genetischer Ressourcen. Im Agrobotanischen Garten des Instituts für Ackerbau in Cluj-Napoca werden Samenproben von ökonomisch bedeutenden Pflanzenarten, Landsorten und verwandte Wildarten, beginnend seit 1970 gesammelt. Auf dieser Sammlung aufbauend wurden die in Bezug auf ihre Variabilität gefährdeten landwirtschaftlichen Pflanzenarten in Vier Hauptgruppen eingeteilt. Entwicklung und Besonderheiten der Generosion, die sich in diesen Gruppen vollzieht, werden am Beispiel vonTrifolium pratense L.,Phaseolus vulgaris L. undTriticum monococcum L. dargestellt.

---

(. . )

« », , . , o , , . , , ë , . () 1970 . , , . , , , . , , Trifolium pratense L.,Phaseolus vulgaris L. Triticum monococcum L.

     

Understory vegetation,soil structure and soil invertebrates in Congolese eucalypt plantations,with special reference to the invasive plant Chromolaena odorata and earthworm populations

Earthworm relationships with vegetation have received extensive attention, and earthworm density has been shown to be related to vegetation types or plant species. However, the factors involved are rarely known. In Congo, we studied the effect of Chromolaena odorata (L) R.M. King & H. Robinson, which invades eucalypt plantations, on soil invertebrates, especially earthworms. In order to investigate relationships between vegetation cover and soil invertebrates, four understory species, including C. odorata, were studied. Also, comparisons were made between plots invaded by C. odorata and plots free from it. The addition of leaf litter on experimental plots was made in order to check its influence. Plant remains were observed in the digestive tract of earthworms. An increased earthworm density was observed under C. odorata. The leaf litter and roots of this species had low lignin/N ratio. The size of leaf fragments found in the digestive tract of the earthworms, and the lack of short-term effect of experimentally added leaf litter, suggested that litter quality could influence earthworm through their feeding on fine particulate top soil organic matter. The amount of soil aggregates, in the size classes that fitted the size range of earthworm casts, was increased under C. odorata. More field experiments are needed to establish a causal effect in the relationships observed between earthworm density and C. odorata. If so, the major drawbacks, such as water and nutrient competition, resulting from C. odorata overrunning the plantations, could be somewhat offset by its positive effects through soil improvement.