Interactions of native and introduced earthworms with soils and plant rhizospheres in production landscapes of New Zealand (original) (raw)
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Response of endemic and exotic earthworm communities to ecological restoration
Land conversion and environmental changes associated with agronomic practices are believed to have led to the disappearance of New Zealand endemic earthworms from agricultural land. Introduced European earthworms have since largely replaced endemic species in farming systems. We investigated the impact of vegetation restoration on earthworm communities. Recolonization by endemic earthworms increased with time after restoration at two studied sites in the South Island of New Zealand. However, exotic species did not disappear with restoration of native vegetation, even after 30 years. The persistence of exotic species leads to the cohabitation of the two communities and potential for interspecific competition.
Earthworms as colonizers of natural and cultivated soil environments
Applied Soil Ecology, 2011
For cultivated soils, the important function of earthworms as ecosystem engineers and their major contribution to the composition and functioning of soil ecosystems with a varying species diversity has been extensively addressed. However, the role of earthworms as colonizers of virgin, uncultivated soil in the process of soil formation has been little researched and long underrated. To better understand this role, the following questions need to be considered: (1) what makes an early colonizer successful, what are its characteristics, and which species are the most successful and under what circumstances are they successful?;
Functional Ecology, 2017
1. As ecosystem engineers, earthworms greatly affect plant communities. They create persistent soil structures enriched by nutrients that improve the conditions for plant growth and modify competition between plant species. We therefore hypothesized that earthworm activity would be more important in early stages of the primary succession, when the soil is not modified by earthworms, than in the late stages of the succession, when the soil is already improved by earthworms. On the other hand, earthworms also affect plants via many other effects such as seed predation or Accepted Article This article is protected by copyright. All rights reserved. excreting hormone-like compounds, which could make earthworm presence important in late successional soil. 2. To explore earthworm effects on plant community succession, we performed a laboratory microcosm experiment without and with earthworms (Lumbricus rubellus and Aporrectodea caliginosa), with early successional plants (Poa compressa, Medicago lupulina, and Daucus carota) and late successional plants (Arrhenatherum elatius, Lotus corniculatus, and Plantago lanceolata), and with soil previously unaffected by earthworms (young soil) and soil substantially affected by earthworms (developed soil). These soils were taken from the early and late successional postmining sites of the Sokolov coal mining district (northwest Czech Republic). 3. When both early and late successional plants were grown separately, earthworms increased plant biomass proportionally more in the young soil than in the developed soil, indicating that earthworm activity is more important in undeveloped than in developed soil. 4. When early and late successional plants were competing each other, the biomass of the early successional plants was reduced. In the young soil the reduction was independent of earthworm presence. In the developed soil the reduction was promoted by the earthworms. Late successional plants profited from the reduction of early successional plants and increased their biomass. This increase was promoted by the earthworm presence. 5. Our results indicate that the direct effects of earthworm presence on plants decrease during succession because of the cumulative effects of earthworm activity on soil conditions. Such ecosystem engineering effects favor late successional competitors and therefore promote the replacement of species during succession.
Invasive earthworms erode soil biodiversity: A meta-analysis
The Journal of animal ecology, 2017
1.Biological invasions pose a serious threat to biodiversity and ecosystem functioning across ecosystems. Invasions by ecosystem engineers, in particular, have been shown to have dramatic effects in recipient ecosystems. For instance, invasion by earthworms, a belowground invertebrate ecosystem engineer, in previously earthworm-free ecosystems dramatically alters the physico-chemical characteristics of the soil. Studies have shown that such alterations in the soil can have far-reaching impacts on soil organisms, which form a major portion of terrestrial biodiversity. 2.Here, we present the first quantitative synthesis of earthworm invasion effects on soil microorganisms and soil invertebrates based on 430 observations from 30 independent studies. 3.Our meta-analysis shows a significant decline of the diversity and density of soil invertebrates in response to earthworm invasion with anecic and endogeic earthworms causing the strongest effects. Earthworm invasion effects on soil micro...
Attempts to restore native biodiversity into agricultural landscapes in New Zealand appear to be compromised both by soil nitrogen enrichment from farming and N-leakage to the wider environment. We investigated whether interactions between native earthworms and a native rhizobium-inoculated leguminous shrub (Sophora microphylla) have a measurable effect on the mobility of nitrogen in an agricultural soil that has been nitrogen-enriched and colonised by exotic earthworms. Plants grew better in the presence of both native and exotic soil-burrowing earthworms. Rates of root nodulation were considerably enhanced in the presence of the native megascolecid anecic earthworm Maoridrilus transalpinus. This species consumed more organic matter in the presence of inoculated plants whilst marginally lowering soil pH and enhancing critical concentrations of nitrate, but also reducing nitrous oxide emissions. Earthworms raised dehydrogenase enzyme activity and microbial activity in soil, but this was not commensurate with rates of nodulation. Our results show that some combination of earthworm-mediated soil aeration, modification of moisture conditions in the rhizosphere and drilosphere, and comminution of organic matter, modify microbial communities and significantly impact the N cycle.
Soil Biology and Biochemistry, 1992
Earthworms were surveyed in 113 pasture soils in the Mount Lofty Ranges, Fleurieu Peninsula, South Australia, in a region where annual rainfall is 600-1200 mm and the climate is mediterranean. The soils within these pastures included a variety of profile forms (e.g. sandy soils with yellow, brown or red clays in the B horizon; uniform coarse textured sands). The most widespread earthworm species were Aporrecrodea trapezoides (found at 95% of sites), Microscolex dubius (61%). Aporrectodea rosea (38%) and Aporrectodea culiginosu (36%). These are all introduced species. The total densities of earthworms varied from 0 to 608 me2 (mean = 169.2). At most sites (66%). densities were ~200 m-*. Native earthworms were present at 40 sites but their total densities exceeded 100 m-* at only 7 sites. The species richness and diversity of the earthworm communities were low; never more than 5 species were found in any one pasture (mean = 3.1). The abundance of the introduced species (all species combined) varied between soil prolile forms, being least in the uniform sands. No such variation was found for native species. Several significant, but weak, correlations were obtained between the numbers and weights of earthworms and other environmental variables (e.g. rainfall, depth of A horizon, % sand, clay. nitrogen and carbon). Stepwise multiple regression of the numbers and weights of introduced species against these environmental variables suggested that % clay was the most important regressor. The potential for increasing the abundance and diversity of earthworms in Australian soils is discussed.
Invasion of exotic earthworms into ecosystems inhabited by native earthworms
Biological Invasions, 2006
The most conspicuous biological invasions in terrestrial ecosystems have been by exotic plants, insects and vertebrates. Invasions by exotic earthworms, although not as well studied, may be increasing with global commerce in agriculture, waste management and bioremediation. A number of cases has documented where invasive earthworms have caused significant changes in soil profiles, nutrient and organic matter dynamics, other soil organisms or plant communities. Most of these cases are in areas that have been disturbed (e.g., agricultural systems) or were previously devoid of earthworms (e.g., north of Pleistocene glacial margins). It is not clear that such effects are common in ecosystems inhabited by native earthworms, especially where soils are undisturbed. We explore the idea that indigenous earthworm fauna and/or characteristics of their
Diversity and abundance of earthworms across an agricultural land-use intensity gradient
Soil & Tillage Research, 2008
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 rowcrop 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 À2) and coniferous forest (160 m À2); intermediate in the old-field (273 m À2), no-till (328 m À2) and tilled organic (344 m À2) cropping systems; and highest in the old-growth deciduous forest system (701 m À2). 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.