Worm Farm Introduction and Guide

Worm Farming For Profit

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Earthworms phylum Annelida Clitellata Oligochaeta

For general reference and more details on aspects of morphology and ecology, the reader is directed to Edwards (1998), Edwards and Bohlen (1996), Lee (1985) and Grasse's encyclopaedia. The physiology of earthworms is treated further in Laverack (1963). Compared with the onychophorans, for our purpose and in general, the main differences are the elaboration of the circulation system with a capillary network, of nephridial excretion and of the central nervous system. These permit a larger body and more complex behaviour. The body consists of repeated segments, the somites, which are partially independent. There are more organs, and tissue differentiation is more extensive. Lumbricina, or true earthworms The cuticle of earthworms is thin and flexible, so that juveniles grow into the adult size without moults. As in previous taxa, it is secreted by the epidermis however, it is not chitinous, but collagenous and only 1-4 m thick (Jamieson, 1981). The epidermis, as in other tissues of...

Oligochaeta Earthworms

Earthworms are the most familiar and, with respect to soil processes, often the most important of the soil fauna. As observed by many farmers and gardeners and reported in the popular literature, the importance of earthworms arises from their influence on soil structure (e.g., aggregate or crumb formation, soil pore formation) and on the breakdown of organic matter applied to soil (e.g., fragmentation, burial, and mixing of plant residues). These observations have led to numerous studies of the potential benefits of earthworms in agriculture, waste management, and land remediation (Edwards, 2004). While the scientific literature on earthworms officially began with Linnaeus's taxonomic description ofLumbricus terrestris more than 200 years ago, the modern era of earthworm research began with Darwin's (1881) last book, The Formation of Vegetable Mould Through the Actions of Worms, with Observations of Their Habits, which called attention to the beneficial effects of earthworms It may be...

Earthworms

Earthworms have a diurnal rhythm and tend to be more nocturnal, probably to avoid ultraviolet light, solar radiation and desiccation. They are active when there is sufficient moisture and become inactive as the soil dries, by dehydrating and entering dormancy. The earthworms are generally placed into three functional groups based on the observations of Bouch (1977) on Lumbricina. Epigeic species tend to tunnel through the surface litter and organic horizons near the surface. They have a preference for partially decomposed litter and ingest rich organic matter and surface litter. Some species can also be found in animal dung (some species of Lumbricus and Aporrectodea), composts or under tree bark. Anecic species reside in deeper permanent burrows and emerge at night to drag selected leaf litter into their tunnel. The litter is eaten in the tunnel and in some species the excreted material, the earthworm cast, is deposited on the soil surface. Endogeic species tend to remain in the...

Laboratory and Field Exercises in Soil Ecology 299

Berlese or Tullgren Extraction 318 Flotation 318 Emergence Traps 318 Pitfall Trapping 318 Sampling and Enumeration of Earthworms 320 Principle 320 Collection of Earthworms 320 Passive Techniques 320 Behavioral Techniques 320 Indirect Techniques 323 Identification of Earthworms 323 Sampling and Enumeration of Enchytraeids 323 Principle 323 Collection of Enchytraeids 324 Identification of Enchytraeids 325

Biodiversity in Alpine Ecosystems

And the small size of alpine plants, which partly compensates for the altitudinal loss of land area . The altitudinal trends for animal diversity are similar to plants, but some animal taxa decline in diversity with altitude more rapidly (e.g., beetles, earthworms, butterflies) than others (e.g., vertebrates, birds). Often animal diversity peaks at mid-altitudes (close to the treeline ecotone) and then declines.

General history and scope

Stated that soils were classified during the Yao Chinese dynasty from 2357 to 2261 BCE. This dynasty should be recognized for both basic and applied studies of soils as they used a soil classification for taxation purposes. The ancient Chinese regarded earthworms as angels of the earth. Romans, such as Aristotle, considered earthworms as intestines of the earth (Coleman et al., 2004). Further evidence for the early recognition of soil is that the Hebrew word for soil is adama, from which is derived Adam, the first man in Semitic religions (see Hillel, 1991). The ancient Vedic literature of India classified soils by color (and thus organic matter content) and recognized the importance of land forms, erosion, vegetation, land use, and human health implications.

Valuation of Biodiversity

For example, organisms inhabiting soil (e.g., earthworms and insects) are crucial for maintaining fertility and henceforth allow the growth of crops and forests. Another example is the case of plant pollinators. An important number of crops depend on the 'service' provided by wild pollinators. Efforts have been focused to estimate the economical cost that the loss of such ecological services might involve. In the case of pollination by native insects in the USA, a study estimated that the ecological service they provide is worth 3.07 billion per year.

Major Living Organisms of Ecosystems

Omnivores are consumers that eat both plants and animals, for example, pigs, rats, foxes, bears, cockroaches, and humans. These consumers typically hunt and kill live prey. On the contrary, the so-called scavengers feed on dead organisms that have either already been killed by other organisms or have died naturally, for example, vultures, flies, crows, hyenas, some species of shark, beetles, and ants. Detritivores (decomposers and detritus feeders) live off detritus, parts of dead organisms, and cast-off fragments and the waste of living organisms. Decomposers, mostly bacteria and fungi, are consumers that recycle organic matter in ecosystems by breaking down dead organic material (detritus) to get nutrients and release the resulting simpler inorganic compounds into the soil and water, where they can be taken up as nutrients by producers. This is also known as biodegradability. Detritus feeders, such as crabs, carpenter ants, termites, earthworms, and wood beetles,...

Preface and acknowledgments

The book now completed, I will attempt to cover my tracks, and pretend that this was written to fill the 'major gap in scholarship' that is usually recruited in such cases. Thus, I refer to Gruber (1981,p.xix), who, in an influential review of Darwin's work, pointed out that w e need to fill many gaps in our knowledge of detail, and we need new approaches to synthesis. The details wanting are by no means fussy bits. They are, rather, organized chunks or even macro-chunks - for example, a longitudinal and critical reconstruction of Darwin's half-century of work on earthworms. I shall leave the subterranean task of working through Darwin's Grubs to my vermiphile colleagues it is Darwin's Fishes that I herewith offer as a latitudinal 'macro-chunk' and 'critical reconstruction'.

Influence of trees on the degradation of forest soils

Soil acidity increases if land is planted with pines, but this is not necessarily a direct cause for concern as most forest trees are more successful on acid soil. Work done on reclamation of china clay waste, development of vegetation on glacial moraines, marine and fresh water sand dunes, etc. has shown that decline in pH is a consistent phenomenon. The main problem is that of podzolization. For example, in New Zealand, earthworms (which are all introduced) drop in number to a very low level when pastures are densely planted with Monterey pine. This is probably linked to increased acidity and decreased calcium levels. Inevitably this leads to a build-up of mor humus and a locking-up of nutrients. Though improved harvesting methods and use of new machinery have lessened their impact, soil compaction, which commonly occurs when stands are harvested, reduces productivity as does erosion.

Importance of Calcium to Ecosystems

Calcium is an element whose careful regulation within every living organism is critical to its survival. Eukaryotic cells use calcium ions as intracellular messengers, signaling environmental stresses and inducing changes in gene expression. Calcium is also an important structural component of cells, present in cell walls and membranes, and is a counterion for anions in cell vacuoles. The presence of too much calcium is, however, problematic and organisms have evolved ways to manage excess calcium. For example, earthworms contain calciferous glands that excrete calcium carbonate when too much calcium has been ingested and certain tree species (e.g., Norway spruce (Picea abies (L.) Karst.)) are thought to incorporate excess calcium into extracellular calcium oxalate crystals in their foliage.

Microbial Abundance and Distribution in Soil

Unfortunately for the soil ecologist, the distribution and abundance of microorganisms is so patchy that it is very difficult to make an accurate determination of their mean abundances without dealing with a very high variance about that mean, when viewed on a macro scale. Part of this variation is due to the close tracking of organic matter patches by the microbes. There are aggregations of microbes around roots (the often-cited rhizosphere ) (Lynch, 1990), around fecal pellets and other patches of organic matter (Foster, 1994), and in pore necks (Fig. 3.3) (Foster and Dormaar, 1991). In addition, microorganisms concentrate in the mucus secretions that line the burrows of earthworms (the drilosphere, as defined by Bouch 1975 and reviewed by Lee 1985 ). The phenomenon of patches is discussed more in Chapter 6.

Case Histories And Ecosystem Surveys

Studies conducted in the vicinity of mining operations and smelters have provided some of the most revealing examples of environmental damage caused by metals and associated contaminants. Metal-contaminated soils eroded from exposed and disturbed landscapes and tailings generated during processing may be released to the environment and are associated with increased metal concentrations in surface water and groundwater. Similarly, dispersed sediments often become deposited as alluvial materials in riparian areas and can result in soil metal concentrations greatly exceeding predepositional conditions. Henny (Chapter 26) reviews the history and cause of waterfowl mortality in the Coeur d'Alene (CDA) River Basin of Idaho related to mining sediment containing high concentrations of lead and other metals. Diagnostic procedures and techniques to assess lead poisoning are discussed. Beyer and co-workers20 concluded that exposure of waterfowl to lead in the CDA River Basin was principally...

In a Fragmented Landscape

Several species of European earthworms are invading hardwood forests in eastern North America (Lee 1995). Of these, the nightcrawler (Lum-bricus terrestris) is the most aggressive at eating the forest floor leaf litter (Alban and Berry 1994), leaving the bare soil susceptible to erosion and changing the environment in which seeds germinate. We know that European earthworms will cause species-and ecosystem-specific changes in seed bank and seed bed dynamics in old-growth forest remnants, creating the potential for major changes in successional trajectory in the future, for both the tree layer and the herb layer (Nielsen and Hole 1964, Nixon 1995). Because of the newness of investigation into earthworm effects on forests, however, we have more questions than answers.

Changing the Niche Space Niche Construction and Coevolution

Both environment and species change in the course of time, and thus ecological niches are not stable and given forever. Species not only respond to environmental changes, but also actively change their biotic and abiotic environment, affecting both their own niche and the niches of other organisms. The importance of competition, predation, or mutualism has been already stressed. Moreover, organisms often make niche space for other organisms available in the environment - think of successive colonization of an island where first colonizers modify environment for their successors, internal (endobiotic) organisms, or emerging trees. Some organisms strongly directly affect abiotic environment, determining possible niches for a whole community of species - beavers building dams, earthworms altering soil structure, or, on a larger scale, plants providing oxygen are classical examples. Organisms substantially affecting abiotic environment are often called 'ecosystem engineers' and the...

Importance Of The Macroarthropods

OLIGOCHAETA (EARTHWORMS) Earthworms are the most familiar and, with respect to soil processes, often the most important of the soil fauna. The importance of earthworms arises from their influence on soil structure (e.g., aggregate or crumb formation, soil pore formation) and on the breakdown of organic matter applied to soil (e.g., fragmentation, burial and mixing of plant residues). The modern era of earthworm research began with Darwin's (1881) book, The Formation of Vegetable Mould through the

Direct Effects Of Exploitation

Exploitation in soil biota is widespread. Most soil animals, including protozoa, nematodes, collembola, mites, earthworms, etc., obtain their resources through exploitation of bacteria, fungi, or plant roots. Invertebrates that ingest plant detritus normally get most of their energy and nutrients from microorganisms residing on the detritus (their prey ) rather than directly from the detritus. Many species of fungi have been shown to attack bacterial colonies and other fungi, and there are also fungi that attack soil animals. Bdellovibrio is a bacterial predator that attacks other bacteria. All organisms also appear to serve as a habitat for an assemblage of smaller organisms, many of which are parasitic.

Short Environmental Encyclopedia

Another use of decay is compost a mixture of the organic matter (old potato peelings, grass cutting, shredded newspaper) under right conditions (warmth, moisture, oxygen). Compost holds moisture and plant nutrients (chemicals that the plants need to grow), provides food for earthworms and kills weeds (plants growing where they are not wanted). There are also animals, insects, fish that are also very sensitive to the water pollution. If there are only red worms, water is badly polluted. If there are the trout in water, its quality is high.

Historical And Geographic Contingency

Human activity has greatly increased the transport of materials around the globe. Earthworms from Europe were introduced to the Atlantic coast of North America and have been steadily colonizing new soils each year. The root pathogen Phytophthora infestans was introduced from Mexico to the United States and then was transferred to Europe (causing the Irish potato famine) and from there to the rest of the world (Goodwin et al., 1994). Transport of soil is now the subject of international law and regulations. The difference in effects of the introduced species in these two examples is interesting, given the questions raised above. P. infestans in agroecosystems has a substantial impact because it is involved in aggressive exploitation of the dominant plant (an important ecosystem engineer) and clearly causes system reorganization. On the other hand, earthworms play the role of a detritivore involved in comminution of plant tissue. This can be considered a weakly interacting mutualism...

General Attributes Of Fauna In Soil Systems

In recent years, interest has been shown by soil scientists and ecolo-gists in measuring soil quality. This elusive concept has been the subject of entire symposia and volumes resulting from them (e.g., Doran et al., 1994). As defined by soil scientists, soil quality can be considered as the degree or extent to which a soil can (1) promote biological activity (plant, animal, and microbial) (2) mediate water flow through the environment, and (3) maintain environmental quality by acting as a buffer that assimilates organic wastes and ameliorates contaminants (Linden et al., 1994). Many environmental scientists are attempting to use the concept of indicator organisms or indicator communities as a way to determine overall soil health (e.g., Bongers, 1990 Ettema and Bongers, 1993 Foissner, 1994 Linden et al., 1994 Neher et al., 1995 Ferris et al., 2001). Because of their large size and public awareness of them, earthworms are often considered a sign of soil health (Linden et al., 1994...

Anelasma squalicola See Barnacles

Annelids (-idae) Aclass of worms in which the surface of the body exhibits a more or less distinct division into rings or segments, generally provided with appendages for locomotion and with gills. It includes the ordinary marine worms, the earthworms, and the leeches (Origin VI, p. 431 by ordinary marine worms, CD means bristle worms, or polychaetes, of which he often uses the genus Nereis as a representative. Hence his vision of chalk-making nereidous animals in the *Cretaceous. See also Dohrn.)

Direct Effects Of Invertebrates On Fungi Mycophagy

While feeding within fruit bodies, invertebrates inevitably ingest spores. Passage of spores through guts can result in considerable damage resulting in failure to germinate, for example, Agrocybe sp. after passage through the gut of earthworms (Lumbricus terrestris Moody et al., 1996). Some Collembola completely break open spores during gut passage, for example, Hypogastrura spp. feeding on cultivated Hypsizygus marmoreus, though damage varied between Collembola species (Nakamori and Suzuki, 2005a, 2005b). Those species with greater spore-breaking capabilities were more commonly found in the spore-bearing regions of fruit bodies of saprotrophic and mycorrhizal agarics, compared with those with lesser abilities that were found elsewhere in fruit bodies.

Faunal Feedbacks On Microbial Community Composition And Diversity

Since the time of Darwin's epochal book on soil biology (1881), there has been considerable interest in the effects of fauna on microbial communities. Satchell (1983), in a centenary celebration of Darwin's book, stated that, by the culture methods existing up until then, there was little or no indication that earthworms have a qualitatively different flora

Components Of Soil Structure

Macropores are of particular importance in determining soil aeration and rapid water entry. In some soils (notably vertisols), large cracks form on drying and act in this regard at least during initial wetting. Large macropores created by the biota are known as biopores and functionally-effective, near-vertical pores are created in almost all soils by root growth and decay, earthworms, termites, ants and other burrowing invertebrates. Additionally, larger voids and horizontal galleries and chambers also occur that may not be continuous with the surface. In one particularly well-aggregated tropical inceptisol, Radulovich and Sollins (1991) showed that water flowed through the macropores at zero potential (and could be collected in zero potential lysimeters) even though the remaining soil was at less than field capacity (see definition in section I.2.2.2.2).

Impacts on the environment and human health

In the EU and North America, the environmental risks of human and veterinary medicines now need to be assessed before a product can be marketed and in order to perform the risk assessment, data are often required on the effects on aquatic and terrestrial organisms (Breton & Boxall 2003a). A reasonable body of data is therefore available on the effects of many medicines on aquatic invertebrates, fish and algae, earthworms, plants and soil microbes (e.g., see Boxall et al. 2004a). These data have generally been obtained using standard ecotoxicity studies and the studies are often short lived with mortality as the endpoint. Generally, effects occur at much higher concentrations than those measured in the environment.

Environmental fate of degradates

Data have been generated on the ecotoxicity of pesticide, veterinary medicine and biocide degradates because of the requirement of regulatory schemes (e.g.,the EU pesticide directive 91 414 EEC requires that all major degradates formed at 10 of the applied parent compound are evaluated). Generally, these studies have determined acute effects on organisms used in standard toxicity tests (e.g., Daphnia, rainbow trout, earthworms) the reason being that, for the vast majority of pesticide metabolites, the acute package demonstrates no risks, so no further testing is triggered. A few studies have, however, assessed sub-lethal and longer term effects (e.g., Osano et al. 2002a, b). The impacts (both acute and longer term) of a few industrial substances have also been investigated, most notably degradates of the non-ionic surfactants (nonylphenol mono- and diethoxylates, nonylphenol carboxylates, nonylphenol ethoxycarboxylates and nonylphenol itself). These substances are believed to have...

Population Growth and Natural Resources

Population growth, including the spread of humans into natural habitats, causes the loss of biodiversity. Many organisms provide essential service for agriculture and other aspects of human life. For example, if bees were lost, approximately 33 of all world food would be lost. The organisms in the soil play a vital role in recycling waste organic matter and contribute to soil formation. For example, the earthworms and fungi in the soil weigh more than 3000 kg per ha. The average weight of humans per hectare in the US is only 68 kg.

Dynamics And Impairment Of Soil Structure

The important role of the macrofauna in aggregate formation in most soils (Bal, 1982 van Breemen, 1993) is due to their promotion of primary binding through their mechanical activities and intestinal mixing (Barois et al, 1993). They also produce macro-scale structures ranging from faecal pellets (250 m to several centimetres) to large subterranean structures such as termite and ant nests. Earthworm faecal pellets may accumulate to such an extent that certain soils have been called 'vermisols' (Pop and Postolache, 1987). Probably the two most important faunal groups in aggregate production are earthworms (Hopp and Hopkins, 1946 Marinissen, 1995 Blanchart et al., 1997) and termites (Eschenbrenner, 1986 Garnier-Sillam et al, 1988a Miklos, 1992) while such groups as enchytraeids (Didden, 1990 van Vliet et al, 1993) are probably of lesser importance. The stabilities of these structures largely depend on the strength of the primary bindings. Certain structures, such as the fresh casts of...

Faunal Impacts In Applied Ecologyagroecosystems

It is generally acknowledged that zero, or reduced, tillage has several effects on abiotic and biotic regimes in agroecosystems. Retention of litter keeps the surface of the soil cooler and moister than in a conventionally tilled plot (Fenster and Peterson, 1979 Phillips and Phillips, 1984), and also leaves more substrate available in the 0-7.5 cm depths for nitrifiers and denitrifiers (Doran, 1980a, b). This abiotic buffering seems to promote a slower nitrogen cycle, one that continues over a longer time span but at a lower rate per unit time (House et al., 1984 Elliott et al., 1984). Soil invertebrate populations, particularly microarthropods (Stinner and Crossley, 1980 House et al., 1984), and earthworms (Parmelee et al., 1990) are enhanced as well (Table 5.5) (Coleman and Hendrix, 1986). The microarthropods are undoubtedly responding to increased populations of litter-decomposing fungi, which tend to concentrate nitrogen by hyphal translocation (Holland and Coleman, 1987). In...

Role of Abiotic Components

In ecology, it is widely recognized that species interaction can be mediated by a nonliving resource, and that a species can potentially exert a selective force on another species through nontrophic interactions. It should also be noted that in nature many species are very well adapted to modify their community and habitat (e.g., beavers by changing the habitat's hydrological regime, humans by initiating dramatic changes in global climate and geo-chemical fluxes, earthworms by increasing aeration and redistributing organic matter in soil, etc.). Changes in physical characteristics of a habitat caused by the activity of so-called 'ecosystem engineers' may be regarded as an extreme case of such nontrophic interactions. Often, however, even if abiotic components are considered in terms of detrital pathways and or nutrient cycling, the effects studied in detail are mostly confined to trophic interactions only. Furthermore, many indirect interactions occur between different stages of...

Type chemistry and penetrability of soils

Soil invertebrate abundance varies with soil characteristics, especially acidity, which can be measured using a pH meter. Mix soil with twice the volume of distilled water (pH 7) and wait for 10 min before taking the reading. Soil pH depends partly on the type of soil, but it is not readily predictable from soil maps because of the effects of agricultural management and the accumulation of leaf litter. Earthworms tend to be less abundant in acid soil (low pH) and measurements of both pH and earthworm abundance have been found to be good predictors of habitat preferences of earthworm predators such as the Woodcock Scolopaxrustic la (Hirons and Johnson 1987). Some birds that feed on invertebrates in soil or intertidal substrates do so by probing with the bill. For these species the ease with which the substrate can be penetrated may influence the suitability of habitats for foraging. For example, the penetrability of wet grassland soils, was a more important determinant of the duration...

Symbionts Symbiosis with animals

Structured environment, with steep gradients of oxygen and metabolites, with specific and structured communities of bacteria and protozoa (Tholen et al., 1997). The bacterial community consists of aero-tolerant species, facultative aerobes, aerobic and anaerobic species. The protozoa are amitochondriate anaerobes. The presence of oxygen occurs through diffusion from outside, and it is required for digestion of lignin and mineralization of aromatic molecules. The concentration of oxygen decreases to zero away from the gut wall, due to a high consumption rate. The position of the bacteria and protozoa is thus dependent on the oxygen and substrate levels. Some of the spirochetes and rod-shaped bacteria occur as symbionts on the surface of the Hypermastigida and other protozoa, but also inside the cytoplasm (Rother et al., 1999 Patricola et al., 2001). This type of symbiosis between bacteria, protozoa and an invertebrate also occurs in wood-eating cockroaches (Cleveland and Grimstone,...

Symbiosis with plant roots

Lastly, the response of mycorrhizal associations in natural soil depends to a large extent on the edaphic biota (Fitter and Garbaye, 1994 Hodge, 2000). The hyphae in the interstitial pores, and those associated with roots, are in competition for resources with other fungi, protists and bacteria. The hyphae are also grazed by a variety of invertebrates (Collembola, other microarthropods, enchytraeids and earthworms), protists and several Actinobacteria. As we saw earlier, there is some preference for different species when grazing. Moreover, the interconnecting mycelium between different plants redistributes resource sinks within the mycelium network, according to plant species nutrient requirements. One should account for unexpected interactions that occur with the rest of the soil community. For example, in one study, the microcosm set-up revealed that Collembola in the soil were being captured and digested by the ectomycorrhizal fungus Laccaria bicolor (Klironomos and Hart, 2001)....

Food abundance and availability

The abundance of soil invertebrates can be assessed by hand sorting or otherwise separating them from the soil cores. However, this may include animals that are inactive or too deep in the soil to be available to the birds. Chemical extraction of soil invertebrates by applying a solution of an irritant chemical such as mustard to a quadrat in the field (Ausden 1996), appears to measure a combination of abundance and activity or proximity to the surface because the number of earthworms extracted per unit area shows short-term variations that are correlated with soil moisture levels that affect earthworm behavior (Green et al. 2000).

Phylogenetic Constraints

Nematode parasitism probably did not evolve until animals invaded land, about 430 million years ago (Chabaud, 1954, 1955 Anderson, 1984). Thus, there are almost no nematode parasites of marine groups, such as molluscs, polychaetes and crustaceans, but a rich nematode fauna in terrestrial groups, such as earthworms, insects and terrestrial molluscs (Anderson, 2000). The entire group of monoxenic (one host) intestinal nematodes are thought to have evolved from free-living, bacteria-feeding soil nematodes, and the first mode of transmission was not by oral ingestion but through skin penetration (F lleborn, 1929 Adamson, 1986, 1989). In this scenario, nematode parasitism began with the accidental penetration of the moist skin of an early amphibian host (Fig. 11.2). The free-living nematodes probably already used the skin of an animal as a mechanism to avoid dry periods in the environment and as transportation between suitable habitats (Dougherty, 1951 Chabaud, 1982). After penetrating the...

Factors Influencing Cycling Processes

Often in excess amounts that leach into groundwater and streams. Exotic species also can alter nutrient cycling processes. Liu and Zou (2002) reported that invasion of tropical pastures and wet forest in Puerto Rico by exotic earthworms significantly increased decomposition rates.

Soils And Gaia Possible Mechanisms For Evolution Of The Fitness Of The Soil Environment

As far as favorable soil properties are concerned, changes and general improvements in soil porosities and aggregation as well as soil organic matter status are prime examples of general improvements in soil characteristics these changes occur through cumulative interactions of the soil biota. This is not a simple linear progression however there are examples of surface-feeding earthworms, which remove enough of the surface leaf litter material to cause a greater amount of soil erosion in their presence than in their absence (Johnson, 1990). At both ecosystem and global scales, there are significant effects of biota on rock and soil weathering. The early pioneering researches of Vernadsky (1944, 1998) and Volobuev (1964) in particular originated and made popular the concept of organic weathering. The able partnership of roots and microbes in mineral translocation is noteworthy, for example, removing the interlayer K from phlogopite (vermiculitization) within the first 2 mm of the...

Plutonium Ecotoxicity

The understanding of plutonium ecotoxicity is limited by the number and types of studies conducted with the radionuclide. In aquatic systems, increased mortality and developmental effects in carp and fathead minnows occur at activity concentrations as low as 5.97 x 10 pBqmP1. In terrestrial systems, decreases in population density have been observed in earthworms, mites, and microar-thropods. Moreover, genotoxicity has been identified in terrestrial plants with effects to somatic cells. Plutonium toxicity at contaminated field sites is complicated by co-contaminants such as uranium-235 and -238 and other nonradioactive metals.

Patterns in the distribution of soil mites

Resources through competition and predation effects, as well as parasitism on the mites or their symbionts impact the reproduction potential and species dynamics. Studies that fail to account for these factors provide an overly simplistic analysis that may lead to contradictory results when compared with other studies. In reviewing 20 selected data sets, representing deciduous and coniferous forests, pastures, meadows, agricultural fields and forests with mor, moder (lower in earthworms) and mull (higher in earthworms) forest soils, the following generalities were proposed (Maraum, 2000). 3. The transformation of moder to mull soils by earthworms is accompanied by changes in pH and a reduction of oribatid abundance. This observation is consistent with other studies, though the interaction between earthworms and mites is more complex (McLean and Parkinson, 2000).

Other Approaches to Reproductive Toxicity Assessment

One common approach to assessing reproductive toxicity involves the use of 'toxicity tests' (also termed bioassays). Here, a standardized test species (e.g., fathead minnow, manure worm, the amphipod crustacean, Hyalella azteca) is exposed to a contaminated medium (such as site topsoil, whole effluent from a water treatment facility, or a specified dilution of the effluent) while under highly controlled laboratory conditions. Often the test endpoint, or one of several, is a reproductive one. Extreme care must be taken to ensure that the site-specific media samples satisfy the requirements to rear and maintain the test species. Certain invertebrates, for example, only fare well when species-specific sediment grain size specifications are met. Other species may only be able to tolerate a very narrow salinity range. Should essential life-supporting features of the contaminated site's media not well match those of the commercially available test species to be used, the situation may be...

Earthworm distribution in soil

Earthworms have a diurnal rhythm and tend to be more active at night, probably to avoid ultraviolet light, solar radiation and desiccation. They are active when there is sufficient moisture and become inactive as the soil dries, by dehydrating and entering dormancy. Even endogeic species emerge at night and can be trapped on the surface as they migrate. The effect of seasonal changes on cocoon production, emergence and amount of rainfall can cause masses of earthworms to migrate through the profile, or across fields. In some cases, mass migrations uphill or downhill are reported at specific days seasonally, presumably as earthworms seek more favourable conditions (in Lee, 1985). Earthworms that emerge from flooded burrows during rainfall events can be washed away to new areas. Colonization and local spread of a population are often of several metres annually. In a review of the literature (Lee, 1985), there were no evident trends between abundances and amount of species diversity for...

Types And Patterns Of Detritivory And Burrowing A Detritivore and Burrower Functional Groups

General functional groupings for detritivores are based on their effect on decomposition processes. Coarse and fine comminuters are instrumental in the fragmentation of litter material. Major taxa in terrestrial ecosystems include millipedes, earthworms, termites, and beetles (coarse) and mites, collembolans, and various other small arthropods (fine). Many species are primarily fungivores or bacteriovores that fragment substrates while feeding on the surface microflora. Many fungivores and bacteriovores, including nematodes and protozoa, as well as arthropods, feed exclusively on microflora and affect the abundance and distribution of these decomposers (e.g., Santos et al. 1981). A number of species, including dung beetles, millipedes, and termites, are coprophages, either feeding on feces of larger species or reingesting their own feces following microbial decay and enrichment (Cambefort 1991, Coe 1977, Dangerfield 1994, Holter 1979, Kohlmann 1991, McBrayer 1975). Many detritivores...

Definition and Occurrence

Given their wide biogeographic range, savannas occur on a number of soils types, typically oxisols, ultisols, entisols, and alfisols (using US soil taxonomy). In general, these soils are ancient and highly weathered, low in organic matter and cation exchange capacity (CEC). Oxisols occur in tropical savanna regions of South America and central and eastern African savanna and consist of highly weathered, transported, and deposited material occurring on fluvial terraces. Extensive weathering of primary minerals has occurred and they are dominated by clay minerals such as kaolinite and gibbsite which have low CEC. Also present in the soil are acidic Fe and Al sesqui-oxides, which limits nutrient availability, especially phosphorus. Savanna soils tend to be sands to sandy loams, deep and well drained but with low soil moisture-holding capacity. Entisols that occur in Australian savanna also feature the occurrence of ferruginous gravels, further reducing water- and nutrient-holding...

Hydrology of wet grasslands

Waders on grassland feed on invertebrates in the soil (primarily earthworms Lumbricidae and leatherjackets Tipulidae), amongst vegetation, and in shallow pools. Flooding previously unflooded grasslands creates a short-term flush of displaced soil invertebrates, which can attract waders and other species. However, soil invertebrates are slow to re-colonize areas vacated during flooding. This means that flooding large areas of wet grassland, either at the same time or on rotation, is likely to greatly decrease the total abundance of prey for waders (Ausden et al. 2001). One effective way of maintaining suitable conditions for breeding waders in the long-term is to maintain a mosaic of unflooded grassland with a high water table (if soils are suitable see below) on which waders can nest and feed on soil invertebrates, and shallow pools that sequentially dry out and concentrate aquatic prey during the breeding season (Ausden 2001). This is easiest to achieve on sites with varied...

Conceptual Organization of Soil Organisms

A third approach integrates spatial scale and trophic perspectives, linking specific spatial scales to soil processes. Ecosystem engineers, such as earthworms and termites, can indirectly influence the cycling of nutrients through direct impacts on soil structure. A second group is considered the litter transformers (micro- and macro-arthropods) and fragments or comminutes litter into smaller pieces, thereby increasing the surface area available to microbial decomposition. Members of a third group are part of a 'micro-food web', and include microbes and microfaunal predators (primarily nema-todes and protozoa). Each level in this conceptual scheme influences ecosystem properties through actions at different size, space, and timescales.

Regulation of population growth

That would produce artefactual results. In part, the effects of density-dependent reduction in reproduction rates or fertility become evident over longer time periods than the duration of short microcosm experiments. There are also density-independent factors that regulate the growth and abundance of individuals. These include soil temperature, moisture and aeration status, on a diurnal to seasonal scale. It can be argued that in soil, substrate limitation or overcrowding is probably infrequent. Density-independent parameters would then determine whether species are active or inactive according to a range of suitable conditions for activity of each species. In reality, both density-dependent and density-independent parameters must be considered. However, they may not affect the food web at the same spatial scale or time scale. For example, density-independent parameters are more important in regulating population sizes in the short term. Individuals...

Regulation of nutrient flux rates

It is increasingly dubious from a biological perspective whether soil communities recover rapidly from stress and disturbance. Clearly some species are good colonizers, but it is unlikely that all functional groups return rapidly. It is also unclear whether sufficient early colonizers return to maintain all functional groups active throughout the seasons. In general, old mining sites, abandoned bare mineral soil, clear-cut forests and agricultural fields each require years to decades to accumulate all functional groups, and even more years to accumulate species diversity resembling undisturbed sites. These sites tend to be dominated by bacterial communities at first, with some bacterivory. The full complement of testate amoebae, ciliates, nanoflagellates and fungal sapro-trophs requires much longer in the succession sequence to accumulate. The majority of species of microarthropods, enchytraeids and earthworms accumulate slowly because they are poor at dispersal. In particular, some...

Behavioral Techniques

Several approaches have been taken to extracting earthworms from soil based on their behavioral response to certain stimuli. A number of Soil saturated with chemical irritant (e.g., 0.2 formalin) causing earthworms to emerge onto soil surface Soil blocks or cores suspended under heat lamps in water into which earthworms migrate Separates earthworms from soil and plant debris cocoons and small individuals collected Laborious may not collect deep-burrowing species, small earthworms, and cocoons Laborious may not collect deep-burrowing species Heat extraction is a modification of that used for enchytraeids (discussed in next section). Soil cores or blocks are placed in pans of water and exposed to heat from overhead light bulbs earthworms are collected from the water after several hours. This technique was more effective than hand sorting or formalin extraction on small earthworms in dense root mats (Satchell, 1969). As with hand sorting, it is not effective on deep-burrowing, anecic...

Darwins Fishes a dry run

Parrotfishes CD sampled parrotfishes in both *Tahiti and the *Cocos Islands. While the species in question were not new to science, CD's thoughts about the ecological role of parrotfishes turned out to anticipate his later work on the slow work of earthworms he believed that parrotfishes, by consuming corals and defecating calcium carbonate, had created the chalk layers that characterize the *Cre-taceous, only to be rebuffed by a naturalist, William Buckland, who was often wrong, but not on this. CD also tested whether parrotfishes contain poison, which they do. He also misspelled parrotfish (genus Scarus) to *Sparus, which earlier editors of his work failed to notice. Thus, if you turn to the entry on parrotfishes (p. 154) you will see that it is linked through the asterisked entries to

Detritivores and specialist microbivores

Images Detritivores

Microfauna (including the specialist microbivores) includes protozoans, nematode worms and rotifers (Figure 11.3). The principal groups of the mesofauna (animals with a body width between 100 pm and 2 mm) are litter mites (Acari), springtails (Collembola) and pot worms (Enchytraeidae). The macrofauna (2-20 mm body width) and, lastly, the megafauna ( 20 mm) include woodlice (Isopoda), millipedes (Diplopoda), earthworms (Megadrili), snails and slugs (Mollusca) and the larvae of certain flies (Diptera) and beetles (Coleoptera). These animals are mainly responsible for the Long ago, Charles Darwin (1888) estimated that earthworms in some pastures close to his house formed a new layer of soil 18 cm deep in 30 years, bringing about 50 tons ha-1 to the soil surface each year as worm casts. Figures of this order of magnitude have since been confirmed on a number of occasions. Moreover, not all species of earthworm put their casts above ground, so the total amount of soil and organic matter...

The relative roles of decomposers and detritivores

Litter Decomposition Forest

Figure 11.7 The relative importance in forest litter decomposition of microflora in comparison with arthropods, earthworms and nematodes, expressed in terms of their relative content of nitrogen - a measure of their biomass. Microbial activity is much greater than that of detritivores but the latter is more constant through the year. (After Ausmus et al., 1976.) Figure 11.7 The relative importance in forest litter decomposition of microflora in comparison with arthropods, earthworms and nematodes, expressed in terms of their relative content of nitrogen - a measure of their biomass. Microbial activity is much greater than that of detritivores but the latter is more constant through the year. (After Ausmus et al., 1976.)

Herbivorous mammals and birds

Rainforest Herbivores

The domestic pig was derived, is common through Europe, North Africa and through Asia to Japan, and is being seen again in southern England (after an absence of four centuries) following its escape from captivity (Fig. 4.14). In 2003 it was estimated that a population of over 1000 animals had built up. The wild boar is a highly intelligent and fast-moving animal which can weigh up to 180 kg and be 2 m long. Its lower canines rise straight up outside the mouth and point backwards towards the eyes these formidable tusks can rip open the body of an adversary. Males join the herds, each of which is led by an old sow, in December and January. They leave again after the rutting season and the attractively striped young are born 3-4 months later. Though individual animals are good at concealing themselves, wild boar leave unmistakable traces in the forest. They are omnivorous (eating anything with food value), consuming seeds, fruits, bulbs, insects, earthworms, reptiles, small mammals, and...

Feeding on vertebrate feces

Bison Excrament Fungi

Herbivore dung is also sufficiently thickly spread in the environment to support its own characteristic fauna, consisting of many occasional visitors but with several specific dung-feeders. Dung removal varies both seasonally and spatially. In tropical and in warm temperate regions most activity occurs during summer rainfall, whereas in Mediterranean-type climates dung removal is highest during spring after the winter rainfall and again in mid-summer when temperatures are high (Davis, 1996). Dung removal also occurs at greater rates in unshaded situations and is faster on sand than on harder, more compacted clay soils (Davis, 1996). A wide range of animals are involved, including earthworms, termites and, in particular, beetles.

The nature offorest soils and their influence on the ground flora

Soil Catena Podzol Brown Earth

Over, pulling their root plates out of the ground often with large amounts of soil attached. In other cases, trunks fall after the major roots have decayed and the soil is not greatly disturbed, or unfelled trees merely rot while still standing, each simply leaving a stump and fragmented debris. But even these have their effect on shaping the soil the vertical and horizontal channels created by rotting roots act as easy conduits for animals and water. Rooting animals, particularly wild pigs, often cause superficial disturbance, but when grazing is heavy or many walkers use an area (see Section 11.5) the soil becomes compacted. This reduces pore space in the topsoil and increases surface water runoff. The opposite effect is caused by earthworms, moles and other animals which live in the soil and help integrate organic matter and to mix the soil horizons. Humus type is a cause of diversity both below and above ground (Ponge, 2003), besides being most important in determining plant...

Definitions and Terminology Related to Biomagnification

Normalized Concentration

Biomagnification and food web biomagnification were originally coined from observations of chlorinated pesticide bioaccumulation in aquatic food webs. However, the term biomagnification (see Persistent Organic Pollutants) has been applied to other contaminants including mercury, heavy metals, and certain compounds of biogenic origin. The first demonstration of biomagnification was described for dichlorodiphenyldichloroethane (DDD), closely related to the pesticide dichlorodiphenyltrichlor-oethane (DDT), in Clear Lake California. Rachel Carson subsequently used the term 'biological magnifiers' in her book, Silent Spring, to describe how earthworms concentrate DDT residues from soil in their bodies and transfer these residues to robins who consume them which in turn achieve even greater concentrations of the pesticides than worms. The term 'biological magnification' was later used by Woodwell to describe the 'systematic increase in DDT residues with trophic level' in his description of...

Ecology of past forests

Pityostrobus

Though the present separation of New Guinea from northern Australia is relatively recent, their faunas have already diverged. The long-beaked echidna Zaglossus bruijni, which feeds on earthworms, is much larger than its Australian equivalent, the burrowing spiny anteater Tachyglossus auleatus. Moreover, far more of New Guinea's kangaroos live in the trees, where they move rather clumsily, feeding on the foliage and occupying a niche similar to that of many Old World monkeys.

The Role of Organisms in Soil Functions and Processes

Formation Food Chain Ecosystem

Egadrili (earthworms) properties generally increases with larger body sizes. Soil macrofauna, such as earthworms, ants, and termites, can have dramatic effects on soil porosity, creating macropores and tunnels that allow for preferential flow of water into the soil profile. The movement of macrofauna through the soil profile (such as some species of earthworms) can mix mineral particles from one horizon into another, and can

What allows species to coexist in a woodland

Some soil-dwelling organisms facilitate the presence of others. The nest mounds of ants (Fig. 6.8) are hotspots for litter-dwelling earthworms and 37 of the 369 ant-associated species of beetle recorded in Denmark and Fennoscandia are actually dependent on ants (i.e. are myrmecophilous).

Hierarchical Approach To Organisms In Soils

Figure 6.4 (Beare et al., 1995) showing the volumes and biotic groups of concern. The aggregatusphere shows bacteria, amoebae, and some nematodes, having varying degrees of success in gaining access to the prey biota of interest (Vargas and Hattori, 1986). Moving up to a coarser level of resolution, to the rhizosphere, a few millimeters or less in scale one sees the microbes and fauna associated with them, and the considerable feeding and activity which has been documented numerous times. The activities are strongly influenced by abiotic, i.e., wetting and drying events, and the intrusion of new organic substances from growing root tips (Cheng et al., 1993 Kuzyakov, 2002), or deposited feces from microarthropods, enchytraeids, or other mesofauna. The next level of resolution expands from many centimeters to several meters across the landscape, when any of the macrofauna such as earthworms or burrowing beetles come into play. There is then a qualitative shift, brought about by the...

Energy Equations And A Weasels Choice Of Prey

At the other end of the scale are the items that, like insects and earthworms, are so small that the amount of energy gained from digesting them scarcely exceeds that spent in catching them. Earthworm setae were common in the scats of common weasels at Wytham, where the supply of small rodents was barely adequate (King 1980b), and Osgood (1936) observed a female stoat carrying worms to her young. If a hungry weasel comes across an earthworm lying on the surface of the ground, it might snatch it up in passing, but we doubt that a weasel with a stomach full of vole would bother, nor can we imagine even a hungry weasel actually digging for worms.

Physical and Biological Nature

Of all the interacting phenomena in the natural filtration system, microbiological activities are the most important and are carried on by all molds, fungi, bacteria, earthworms, snails, and insects that feed directly or indirectly on the organic waste (see Figure 7.52.1). The mi-

Nematode Extraction Techniques

Soil Fecal Pellets Fauna

In addition to earthworms (discussed under Macrofauna), another important family of terrestrial Oligochaeta is the Enchytraeidae. This group of small, unpig-mented worms, also known as potworms, is classified within the microdrile oligochaetes and consists of some 600 species in 28 genera. Species from 19 of these genera are found in soil, the remainder occur primarily in marine and freshwater habitats (Dash, 1990 van Vliet, 2000). The Enchytraeidae are thought to have arisen in cool temperate climates where they are commonly found in moist forest soils rich in organic matter. Various species of enchytraeids are now distributed globally from subarctic to tropical regions. The Enchytraeidae are typically 10-20 mm in length and are anatomically similar to the earthworms, except for the miniaturization and rearrangement of features overall. They possess setae (with the exception of one genus), and a clitellum in segments XII and XIII, which contains both male and female pores. Sexual...

Soil Aggregation Models

That result in the formation of biological macroaggregates (Fig. 3.12) (Six et al., 2002b). These include the following three processes (1) Fresh plant- and root-derived residues form the nucleation sites for the growth of fungi and bacteria. Macroaggregate formation is initiated by fungal hyphae enmeshing fine particles into macroaggregates. Exudates from both bacteria and fungi, produced as a consequence of decomposition of fresh residues, form binding agents that further stabilize macroaggre-gates (tl A). (2) Biological macroaggregates also form around growing roots in soils, with roots and their exudates enmeshing soil particles, thereby stimulating microbial activity (t0 B to ti)B). (3) A third principal mechanism of biological macroaggregate formation in soils in all climates is via the action of soil fauna, particularly earthworms, termites, and ants. For example, earthworms often produce casts that are rich in organic matter (tl,C) and are not stable when freshly formed and...

Decomposition and Mineralization

Cuffney et al. (1990) and J. Wallace et al. (1991) reported that 70 reduction in abundance of shredders from a small headwater stream in North Carolina, United States, reduced leaf litter decay rates by 25-28 and export of fine particulate organic matter by 56 . As a result, unprocessed leaf litter accumulated (J. Wallace et al. 1995). Wise and Schaefer (1994) found that excluding macroarthropods and earthworms from leaf litter of selected plant species in a beech forest reduced decay rates 36-50 for all litter types except fresh beech litter. When all detritivores were excluded, comparable reduction in decay rate was 36-93 , indicating the prominent role of large com-minuters in decomposition. Tian et al. (1995) manipulated abundances of millipedes and earthworms in tropical agricultural ecosystems. They found that millipedes alone significantly accounted for 10-65 of total decay over a 10-week period. Earthworms did not affect decay significantly by...

Positive Interactions

There are two types of positive interactions, mutualisms and commensalisms (Morin, 1999 Stiling, 1999). Mutualisms occur when all species involved gain some benefit from the interaction. Well-known examples of mutualisms include the positive effects generated between fungi and algae that produce lichens found on rocks or trees, corals and microscopic algae that form the ocean's tropical reef systems, flowering plants and their insect pollinators, and fungi or bacteria and the roots of most plants on earth. Commensalisms occur when at least one species benefits from the interaction but the other species have a neutral response. Commensalisms include common and general relationships, such as trees providing living space or attachment sites for birds, bee hives, or orchids. In addition, animals including beavers, earthworms, and prairie dogs can physically modify or engineer habitats, creating more hospitable conditions or greater resources for other species.

PolychaetaA Multitude of Many Bristled Worms

Scolelepis squamata, a polychaete found on sandy beaches where the worm suspension feeds by extending two palps from burrows. B. Two earthworms exchanging sperm during reproduction. A. Scolelepis squamata, a polychaete found on sandy beaches where the worm suspension feeds by extending two palps from burrows. B. Two earthworms exchanging sperm during reproduction.

Clitellata Oligochaetes and Leeches

The subclass Oligochaeta contains more than 6,000 species distributed among at least twenty-five families. Oligochaetes are found mostly in freshwater and terrestrial habitats, although approximately 500 species have invaded marine areas. They range in size from interstitial species (of less than 1 mm) to giant Australian earthworms that reach lengths of more than 3 m and are considered one of the most endangered animal species. The Lumb-ricidae (with more than 300 species) contains those earthworms, which are perhaps the most familiar representatives of the Annelida. Most oligochaetes are detritivores, feeding on dead organic material. These worms have simple, conical prostomiums without head structures, and chaetae are present but in reduced numbers from polychaetes. The stout chaetae aid in burrowing, and earthworms are thus able to perform the ecologically important functions of aeration and decomposition in soils. The Euhirudinea, or true leeches, are carnivores that derive...

Estivation Summer Dormancy

Among invertebrates (e.g., earthworms and insects) estivation usually involves an inactive stage with a water-resistant covering. For example, estivating earthworms form a mucus cocoon to resist desiccation, and many insect pupae are remarkably resistant to water loss. Amongst vertebrates, fishes, amphibians, and reptiles enter a similar estivation state. Fishes and amphibians often form a cocoon of dried mucus (e.g., African lung-fishes) or shed epidermal layers (e.g., some desert frogs Figure 3) to resist epidermal water loss the cocoon covers the entire body surface except for the nostrils. Reptiles have a relatively water-impermeable epidermis and do not need to form a cocoon to reduce evaporative water loss. Estivating ectotherms typically have an intrinsic metabolic depression for energy conservation.

Ecological Engineering Agroforestry System Design

Recent studies that tree incorporation in pastures leads to retention of more phosphorus in the system and thus prevention or reduction of the chances of its transport from the coarse textured soils of Florida to adjacent water bodies corroborate the premise of silvopasture-system design. Another example is the intercropping of trees with agricultural crops in the temperate zone (Figure 1b), where trees are planted in widely spaced single or double rows in agricultural fields. Although the trees use up about 10 of land, this 'loss' will be more than offset economically and ecologically by production and service value coming from the tree component. Ecological benefits of intercropping that have been monitored in such a system in eastern Canada during a 20-year period include enhanced biodiversity (of birds, earthworms, and beneficial insects), soil organic matter buildup, synchronous development of tight nutrient cycles that prevent nutrients leaching into adjacent waterways, and...

Home Range Size and Population Social Structure

Of more than one individual, an economically defendable home range that is large enough to sustain an individual or a mated pair of individuals is likely to support the foraging needs of one or more additional individuals. Two animals whose home range patterns appear to fit this reasoning are red foxes and badgers in England. Due to the patchy, ephemeral nature of earthworms (a key prey resource for both species), mated pairs of individuals defending a home range large enough to satisfy their own energetic requirements incur relatively little cost from resource consumption of additional individuals and benefit from the cooperative defense of the shared home range. Similar arguments have been made for other carnivores, and for species in other animal groups, including primates, ungulates, and birds.

Biodiversity

Second, the low plant diversity reduces animal diversity in the stand, but perhaps less than one would expect. In a cereal monoculture stand, there can be hundreds of species of insects, mites, springtails, snails, slugs, etc. In the soil under a monoculture the biodiversity is almost always extremely high, though usually lower than in natural systems. Thousands, perhaps millions of bacterial species, tens to hundreds of species of earthworms, enchy-traeids, soil insects, springtails, mites, spiders, millipedes, flagellates, amoebae, blue-green algae, etc. can be found. There are no consistent indications that soil functions such as organic matter decomposition is hampered by a low biodiversity under monocultures - a given plant residue will decompose at the same rate under a monoculture as under mixed plants, if soil temperature and moisture are the same.

Annelida

Annelida A phylum of segmented worms that includes the earthworms, bristle worms, lugworms, and leeches. They are found in aquatic, marine, and terrestrial environments. Annelids are distinguished by series of external ringlike segments running the length of the long soft cylindrical body. The body is covered in a cuticle of chitin, and most annelids have segmentally arranged bristles called chaetae, which are used in locomotion. The body wall contains layers of longitudinal and circular muscle and the body cavity (coelom) isolates the gut from the body wall. The gut runs from the mouth to anus, there are well-developed blood and nervous systems, and nephridia for excretion. Many annelids are hermaphrodite. The class Oligochaeta comprise the terrestrial earthworms, and many freshwater species. Ranging in length from a few millimeters to over 3 m they have relatively few chaetae. All oligochaetes are hermaphrodite. Most are scavengers, feeding on decaying organic matter. Earthworms...

The Triassic Period

The Triassic period (250-205 mya) during which the dinosaurs originated,was a time of comparative aridity, of xerophytic vegetation and abundant reptiles. About 200 mya, during the Late Triassic and Early Jurassic, the continental plates of Laurasia and Gondwanaland were united. Some portions of what are now central Asia and China may have remained as separate islands, but most of the landmass of the world was concentrated into the single supercontinent, Pangaea, as we have seen. Consequently,both plants and animals were remarkably similar everywhere. The main vegetation types consisted of seed ferns and conifers which were adapted to the dry climate, while massive horsetails dominated the damper regions. The terrestrial fauna comprised mainly earthworms, again in moister places, snails, arachnids, insects, and reptiles, which either captured earthworms and arthropods in the undergrowth, or else chewed the tough vegetation. Crustaceans, molluscs and fishes populated the lakes and...

Invertebrates

Several taxa of invertebrate organisms need to be considered. The role of these species in the soil interstitial space is inseparable from decomposition processes. They interact with protists and bacteria as grazers, prey or predators. They are presented in three sections as (i) the nematodes, tardigrades, rotifers and gastrotrichs (ii) earthworms and enchy-traeids and (iii) microarthropods, particularly the mites and Collembola. More detail on the structure and function of these taxa can be found in standard invertebrate zoology texts (see Grasse, 1949-1995 Dindal, 1990 Ruppert and Barnes, 1994).

Annelids

Oligochaetes (few bristles) are the class that includes the common earthworm Lumbri-cus terrestris. Most are scavengers, feeding on decayed plant and animal matter. Earthworms are hermaphroditic but must copulate with another individual. Eggs and sperm are then deposited in a mucus and chitin pouch, or cocoon. Earthworms play an important role in the ecology of the soil. Their burrows improve soil drainage and aeration. They mix the soil by ingesting it at depth and depositing it at the surface, and they bring organic matter from the surface down into the burrows, where the nutrients released by their decay can become available to plant roots. Freshwater oligochaetes are smaller but more mobile than their terrestrial cousins. They can be an important source of food for fish. One is Tubifex, a small reddish worm that forms tubes in the sediment in which it lives head down, with tails waving in the water. Tubifex can form carpets on the bottoms of heavily polluted streams. The class...

Overview

Decomposition leaching, fragmentation, and chemical alteration. Leaching is a physical process through which ions (such as K+, Mg2+, and Ca2+) and small water-soluble organic compounds (such as sugars, amino acids, and amino sugars) dissolve in water and move out of the decomposed organic material. Leaching could happen even from green leaves still attached to the plants. These soluble materials move into the soil matrix where they are taken up by plant roots or soil microbes, adsorbed to soil minerals, or leached and transported through the soil column by water drainage. Leaching losses are greatest in environments with high precipitation and negligible in dry environments. Fragmentation is a physical process through which fresh detritus is broken down into smaller particles. During fragmentation, some chemical bases can break off from organic compounds thereby contribute to nutrient mineralization. Fragmentation also provides more fresh surfaces that can be used by microbial...

Soil Organic Matter

One important source of organic matter in the soil is released from soil living organisms as secretions. The sources of these secretions are numerous. They include bacterial cell wall components, protective (or defensive) mucopolysaccharides from protists, mucus from earthworms and secretions from root cap border cells. The plant root cell secretions are called root exudates (Hawes et al., 1998). These consist of various sugars, amino acids, peptides and defensive molecules. The purpose of root tip exudates is to bait potentially infective organisms, or consumers of root cells, away from the growing root tip. Root exudates are responsible for the coagulation of peds along the root. The region adjacent to roots is thus greatly affected by the plant secretions as exudates. This thin layer of soil along the roots is called the rhizosphere, and is supposed to harbour an environment slightly different from the surrounding bulk soil.

The soil atmosphere

Structures created by soil invertebrates, especially the large ecosystem engineers (notably earthworms, termites, ants and beetles, see II.2.4 and Chapter IV) may significantly influence gas diffusion. Kretzschmar and Monestiez (1992), for example, have demonstrated that earthworm burrows significantly increase gas diffusion rates from soils, particularly at high water potentials ( ym -0,3 kPa) where only a small proportion of the pore space is filled with air.

Abiotic Factors

Some organisms alter the spatial arrangement of components of the environment or serve as new habitat themselves. These organisms are called ecosystem engineers and have widespread effects on an ecosystem beyond their own resource use (Jones et al., 1994). Large, competitively dominant organisms such as trees are obvious examples of ecosystem engineers. Earthworms are ecosystem engineers because they bury plant litter and create macropores in soil.

Recycling

Deciduous trees produce a deep layer of decomposing leaves rich in insects, fungi, and bacteria. These organisms provide vital nutrients to the soil by breaking down fallen leaves. As earthworms crawl through this matter, they ingest and later expel it. In doing so, they help mix buried and surface materials. Their tunnels also help aerate the soil and drain off rainwater. The transformation from fallen leaves to usable nutrients can last two years it is a process that brings about the growth of new plants.

Elixirs of Death

FOR THE FIRST TIME in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death. In the less than two decades of their use, the synthetic pesticides have been so thoroughly distributed throughout the animate and inanimate world that they occur virtually everywhere. They have been recovered from most of the major river systems and even from streams of groundwater flowing unseen through the earth. Residues of these chemicals linger in soil to which they may have been applied a dozen years before. They have entered and lodged in the bodies of fish, birds, reptiles, and domestic and wild animals so universally that scientists carrying on animal experiments find it almost impossible to locate subjects free from such contamination. They have been found in fish in remote mountain lakes, in earthworms burrowing in soil, in the eggs of birds and in man himself. For these chemicals are now stored in the bodies of...

Pellet analysis

For analysis, the pellets are placed in water until they are easy to tease apart and assessment is made the same way as for droppings (see 10.2.4). For larger prey the head may not be eaten and it is then necessary to identify other body parts. The problem of differential digestions of different species (see 10.2.4) can be even greater for pellets than droppings. For example, Green and Tyler (1989) showed that Stone Curlew pellets contained small mammal bones and hard parts of large insects, but that remains of small arthropods and earthworms occurred only in trace amounts, though remains of all prey were abundantly detectable in droppings. Calibration trials with captive birds (10.2.4) is a solution.

Decomposition

Decomposition of the dead material (necromass) by living organisms can be initiated by fungi living on the phylloplane of the leaf or the rhizoplane of the root (Section 5.5.1), such that decay has started before the leaf hits the ground or before the root is fully dead. Necromass is subsequently colonized by saprotrophic fungi and bacteria, some of which may be preyed upon by certain nematode worms, protozoa and rotifers, but it is this microbial conditioning which enables detritivores, such as various oribatid mites and spring-tails (Collembola), millipedes and woodlice, earthworms and potworms (Enchytraeidae) to exploit the dead remains. Molluscs, ants and termites are less dependent on such conditioning. The term detritivore, as mentioned in Section 1.5, is used here in the broadest sense to include decomposer animals that exist primarily on fungi or bacteria, as well as those which ingest necro-mass. The main role played by these animals is the breaking up (comminution) of the...

Arenas Of Interest

Soils are best considered as the extremely heterogeneous entities they are. This requires that we let the soil work for us (Elliott and Coleman, 1988), and stratify, in a statistical sense, the regions of the soil that are hot spots of activity. These zones include the rhizosphere, aggregates, litter and organic detritus, and the drilosphere, which is that portion of the soil volume influenced by secretions of earthworms (Bouch , 1975) (Fig. 6.4). Each region is a relatively small subset of the total soil volume, but may contain a preponderance of numbers, and more importantly, activity of the soil biota (Beare et al., 1995). Examples include The 5-7 of the total soil that was root-influenced or rhizosphere in extensive pot trials of Ingham et al. (1985) contained a majority (greater than 70 ) of the bacterial- and fungal-feeding nematodes. Ingham et al. (1985) also measured higher biomasses of rhizosphere bacteria in microcosms with large numbers of microbivorous nematodes (greater...

Calciphyllous Plant

The species also favorably affects soil physical properties, probably because of the attraction of earthworms and other macro- and microfauna to the nutrient-rich soil. Activity by these animals alters soil structure. This enhances water infiltration and percolation by increasing soil pore volume (air and water space) about threefold and permeability 20 times that of pine sites adjacent to redcedar stands. Organic matter in the soil doubles, amounting to a difference of three tons of litter per acre. Thus, this species influences the site by increasing available calcium in the soil for the use of plants, as well as by raising the pH.

Human influences

In north-west Europe, Heliovarra and Vaisanen (1984) review the effect of fertilization on microbes and invertebrates. With added nutrients, bacteria dominate the microbes and there is a transitory increase in microfauna such as nematodes but large arthropods and above-ground invertebrates show little response. The authors conclude that most of these effects are due to the decrease in acidity rather than fertilization directly, but this is not the whole story since the number of earthworms decrease despite increased pH.

Tier

Soil provides a measure of general soil health Sub-lethal test, demonstrates whether worms can survive at a given contaminant concentration, but are unable to reproduce properly may be used as surrogate for chronic contaminant effects on a range of soil invertebrates Measures cellular damage (lysosomal integrity) in earthworms may be used as surrogate for chronic contaminant effects on a range of soil invertebrates Sub-lethal test, demonstrates whether springtails can survive at a given contaminant concentration, but are unable to reproduce properly may be used as surrogate for chronic contaminant effects on a range of soil invertebrates Measures the degree of successful emergence of seedlings from seed three test species are used tomato, cabbage and wheat, but may be used as surrogates for other plant species of interest Measures growth rate of plants (tomato, cabbage and wheat) growing on contaminated soils may be used as surrogates for other plant species of interest

Passive Techniques

Hand digging and sorting, which is the most commonly used method for quantitative sampling of earthworms, involves digging pits of known volume (e.g., 25 by 25 by 25 cm), breaking the soil by hand, and collecting all earthworms and cocoons found. Collected specimens are immediately preserved in 70 ethanol or 5 formalin for later counting and identification, or they may be kept alive in cool, moist media for use in experiments. Washing and sieving is an elaboration of hand sorting the soil is dispersed in water, poured through a sieve, and the earthworms and cocoons hand picked from the sieve contents. Bouch and Beugnot (1972) describe mechanical approaches to washing and sieving. Flotation of sieve contents in a high-density solution, such as 1.16-1.20 specific gravity MgSO4, is another means of separating earthworms and other soil fauna.

Indirect Techniques

In summary, digging and hand sorting or washing are probably the most reliable means of sampling earthworms. However, no single method will be adequate to sample earthworm populations in all situations. Combinations of methods will probably achieve reasonable results. For example, formalin or mustard solution can be applied to the bottom of pits previously excavated for hand sorting, to extract deep burrowing anecic forms not sampled by digging (Edwards and Bohlen, 1996). Combinations of various methods may be useful in other situations.

Soils and trees

Moreover, soil is not simply a loose collection of'dirt', it is a complex mix of living and non-living components, consisting of air (soil gases typically 25 by volume), water (25 ), mineral particles (45 ) and organic matter (5 ) the last can be subdivided by weight into around 10 organisms, 10 roots and 80 humus. As described further in Chapters 1 and 7, various soil animals, such as earthworms and arthropods and the micro-organisms, including fungi and bacteria, decompose dead material to release nutrients and form the left-over, rather inert black humus of the soil.

Polychaetes

Fan Worms Strain Water Through Their

Polychaetes are the most diverse and abundant of the worm groups and originally were referred to as a class within the Phylum Annelida, together with the earthworms (Class Oligochaeta) and the leeches (Class Hirudinea), and this classification will be found in many textbooks. Recent studies (both morphological and molecular) on the annelids have failed to show that they are a monophyletic group, and while the earthworms and leeches do form a single clade (the clitellates) their relationship to the polychaetes is still being debated. So, today the term 'polychaetes' is widely used rather than the term 'Annelida' and this group includes all the traditional polychaete families as well as the leeches, earthworms, and the siboglinids, sometimes known as 'beard worms'. This latter group until recently was considered either as one or two phyla and included the Vestiminifera, which are restricted to cold and hot vents, and the Pogonophora, or thin worms found in sediments. But recent studies...

Faunal Constructs

Soil animals, particularly earthworms, termites and ants strongly influence soil structure through the formation of both biopores and aggregates (Figure I.17) resulting from their different feeding and burrowing behaviours (Lee and Foster, 1991). Warner et al. (1989) reported the presence of faunally-created cavities at depths down to 560 cm in a Nonh American mollisol supporting pasture these were attributed to the activities of ants and earthworms although surface evidence of their activity was not necessarily visible. Structures created by soil invertebrates, especially the large ecosystem engineers (see II.2.4 and Chapter IV) may significantly affect gas diffusion. Kretzschmar and Monestiez (1992), for example, have demonstrated that earthworm burrows significantly increase relative diffusivity of gases, especially at high matric potentials where a low proportion of porosity is filled with air. The faeces of soil animals may be deposited within soils as void infillings, in...

Xeric Habitats

Many of the ground-dwelling, wingless cockroaches of Australia are important in leaf litter breakdown. This is particularly true in stands of Eucalyptus, where litter production is high relative to other forest types, leaves decompose slowly, and more typical decomposers such as earthworms, isopods, and millipedes are uncommon (Matthews, 1976). The beautiful Striped Desert Cockroach Desmozosteria cincta, for example, lives among twigs and branches at the base of eucalypts (Rentz, 1996). In hummock grasslands and spinifex, genera such as Anamesia feed on the dead vegetation trapped between the densely packed stems (Park, 1990). The litter-feeding, soil-burrowing Geoscapheini are associated with a variety of Australian vegetation types ranging from dry scle-rophyll to rainforest, and have perhaps the most potential ecological impact. First, they drag quantities of leaves, twigs, grass, and berries down into their burrows, thus moving surface litter to lower soil horizons. Second, they...

Topsoil Formation

Topsoil is the upper layer of the soil profile. It is composed of minerals and rock particles, humus, dead and decaying organic matter, water, and an array of living creatures. The kinds of animals are specific to the location, but in general they include rodents, earthworms, insects, fungi, bacteria, protozoans, and viruses. It is these life forms that digest and decompose the organic matter by feeding on their dead and dying tissues, creating humus. These organisms leave their waste behind as well as their dead bodies, thereby contributing again to the soil by becoming part of its organic matter. Proteins are changed to usable nitrogen compounds, and minerals such as phos Rodents and earthworms move through the topsoil, mixing it and allowing air and water to easily permeate the material. The chemistry of the water in the soil varies in composition and concentration, and thus in the chemical changes effected. These conditions, in turn, determine the variety and abundance of living...

Amphibians

The bizarre caecilians form a group of 161 recognized species of legless, eel-like amphibians, usually cast into five families, found in the wet tropics of the Americas, Africa, India, and southeastern Asia, with outliers of clear biogeographic interest in the Seychelles. They range in size from about 7 cm to 1.5 m, depending on the species. They are also seemingly generalists, eating any animal sufficiently smaller than themselves, especially earthworms, termites, and orthopterans. The number of recognized species has been stable since at least 1985, although because they are generally difficult to collect and external morphological variation is quite limited, the true number of species is likely much higher than currently appreciated. The phylogenetic relationships of the group are not well known, although careful work on this topic suggests the relationships shown in Figure 1. Caecilians are all legless burrowers in mud or leaf litter, and some...

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