Abundance Of Soil Arthropods Research Articles

Effects of water addition on soil arthropods and soil characteristics in a precipitation-limited environment

We investigated the effect of water addition and season on soil arthropod abundance and soil characteristics (%C, %N, C:N, moisture, pH). The experimental design consisted of 24 groups of five boxes distributed within a small aspen stand in Saskatchewan, Canada. The boxes depressed the soil to create a habitat with suitable microclimate for soil arthropods, and by overturning boxes we counted soil arthropods during weekly surveys from April to September 1999. Soil samples were collected at two-month intervals and water was added once per week to half of the plots. Of the eleven recognizable taxonomic units identified, only mites (Acari) and springtails (Collembola) responded to water addition by increasing abundance, whereas ants decreased in abundance with water addition. During summer, springtail numbers increased with water addition, whereas pH was a stronger determinant of mite abundance. In autumn, springtails were positively correlated with water and negatively correlated with mites, whereas mite abundance was negatively correlated with increasing C:N ratio, positively correlated to water addition, and negatively correlated with springtail abundance. Although both mite and springtail numbers decreased in autumn with a decrease in soil moisture, mites became more abundant than springtails suggesting a predator–prey (mite–springtail) relationship. Water had a significant effect on both springtails and mites in summer and autumn supporting the assertion that prairie soil communities are water limited.

Soil arthropod abundance under conventional and no tillage in a Mediterranean climate

We have studied the impact on arthropod populations of conventional tillage and no-tillage systems in maize. Two different corn–weed control programs were assayed: NT, direct drilling of seed genetically modified to tolerate herbicide plus a combination of two pre-emergence and post-emergence herbicides; CT, conventional drilling with an isogenic corn variety plus a pre-emergence herbicide. Management system affected the soil arthropod community, based on major groups. Lower number of arthropods occurred in CT than in NT. Spider and hymenopteran parasitoids, especially those belonging to the families Lycosidae and Diapriidae were the groups that were most clearly affected. The natural field environment seems to favour the presence of Diapriidae. Spiders, in addition to being abundant, behaved in a similar way during both years of each treatment and might therefore be considered as reliable indicator families of the effects of different soil managements on the arthropod population in corn crops. Management system implies alterations on abundance of arthropods populations and natural enemies present in the crop.

Seasonal changes in soil arthropod abundance in the dry evergreen forest of north‐east Thailand, with special reference to collembolan communities

AbstractA soil arthropod community was studied in a dry evergreen forest over a 3‐year period from May 1998 to April 2001. Population abundance, species composition, and community structure were investigated over the 3‐year study period. The soil arthropods consisted of Acari (75.38%), Collembola (16.11%), and others (8.51%), and their abundances showed a clear difference between the rainy and dry seasons. Population abundance of Collembola and Acari were low during drought conditions. The humidity was the most important factor determining distribution, abundance, and survival of soil Collembola in this tropical forest. High predation and low accumulation of organic matter caused low population abundance of Collembola in the tropical habitat. The collembolan community was dominated by a few dominant species over the study period. The pattern of seasonal changes in numbers of Collembola was similar over the 3‐year study period. The species composition of the collembolan community was constant and persistent throughout a 3‐year study period. Thus, the collembolan community showed constancy in its species composition with seasonal variability over the 3‐year study period.

Wild boar and red deer affect soil nutrients and soil biota in steep oak stands of the Eifel

In sloping oak forests of the German low mountain range high wild boar ( Sus scrofa) and red deer ( Cervus elaphus) population densities may affect soil ecological processes by grubbing, grazing, trampling and dunging. We simulated wild boar grubbing in a fenced exclosure and an unfenced replicate and established two adjacent control plots, one fenced, the other unfenced. We evaluated if repeated soil bioturbation and game exclusion by fencing influence soil texture, soil chemical and soil biotic properties in the upper soil over a time period of 2 years. Soil bioturbation was conducted in November 2000 and 2001 creating a grubbing pattern similar to that found in naturally grubbed areas. Soil and fauna sampling was performed in spring and fall of the years 2001 and 2002. Soil bioturbation did not affect soil texture, pH and the contents of organic carbon and nitrogen. In contrast, the contents of potassium and magnesium, the microbial activity and the abundance of saprophageous and predatory soil arthropods were generally lower in grubbed plots compared to ungrubbed control plots ( p≤0.05). The exclusion of game did not improve soil quality. On the contrary, microbial activity and the contents of organic carbon and total nitrogen were elevated outside the fenced exclosure ( p≤0.05) which may be related to the deposition of urine and dung. Our study found that large mammals affect soil nutrient cycling in sloping oak forests either directly by the deposition of urine and dung or indirectly by accelerating nutrient leaching and disturbing the decomposer system in the soils.

Soil arthropods in a developmental succession on the Nouragues inselberg (French Guiana)

Tropical inselbergs are isolated rock outcrops with a special type of vegetation surrounded by rain forest. They are exposed to a harsh climate (alternation of heavy rain and severe drought) and provide few nutrients for plant growth. The aim of our study was to investigate a possible correlation between primary plant succession, size and diversity of soil arthropods. The study site was the Nouragues inselberg, in French Guiana (South America). Nine soil samples (three samples in each vegetation type) were taken for the study of soil arthropod communities and their food habits in three habitat types: Pitcairnia geyskesi (Bromeliaceae), Clusia minor (Clusiaceae) and Myrcia saxatilis (Myrtaceae), which represent three stages in a primary plant succession on this inselberg. Soil arthropods were classified into morphospecies under the dissecting microscope and their food habits were characterized by examining their gut contents under the light microscope. A variation in food habits was observed, cyanobacteria being found in arthropod guts only during the Pitcairnia stage, and were replaced by plant material at the Myrcia stage. Carnivory was prominent in oribatid mites, contrary to temperate records. All our samples contained large numbers of microarthropods, principally mites and collembolans. At the Myrcia stage arthropod density was significantly higher than at the two other stages. Macroinvertebrates are present only at late and intermediate successional stages. The number of macropredators increased by a factor of 10 in species richness and 100 in abundance along the succession. These results suggest that abundance and diversity of soil arthropods increased throughout the plant succession and show the importance of organic matter as a factor which can explain the observed phenomenon.

Dynamics of springtail and mite populations: the role of density dependence, predation, and weather

Abstract 1. Ecological theory suggests that density‐dependent regulation of organism abundance will vary from exogenous to endogenous factors depending on trophic structure. Changes in abundance of soil arthropods were investigated at three trophic levels, springtails (Collembola), predaceous mites (Acari), and macro‐arthropods (spider, adult and larval beetles, centipedes). Predictions were that springtails are predator regulated and mites are food limited according to the Hairston et al. (1960) model, which predicts alternating regulation by competition and predation from fungi to springtails to mites to macro‐arthropods. The alternate hypothesis was based on the bottom‐up model of trophic dynamics, which predicts that each trophic level is regulated by competition for resources.2. The relative contributions to springtail and mite population dynamics of endogenous (i.e. density‐dependent population growth related to food availability) and exogenous (i.e. predation and weather) factors were tested using time‐series analysis and experimental manipulation of water conditions. Box patterns were distributed within an aspen forest habitat located in the Canadian prairies and surveyed weekly from May to September 1997–1999. Each box depressed the leaf litter, creating a microhabitat island for soil arthropods that provided counts of invertebrates located immediately beneath the boxes.3. Strong evidence was found for endogenous control of springtail and mite numbers, indicated by a reduction in population growth related to density in the previous week. Contrary to predictions, no evidence was found for regulation of springtail numbers by mites, or for regulation of mite numbers by macro‐arthropods. Springtail population growth rate was related positively to current springtail density (8 and 23% variation explained) and related negatively to 1‐week lagged density (85 and 58%), and related negatively to temperature (5 and 5%) for time‐series data and for experimental addition of water respectively. Mite population growth rate was related positively to current mite density (54%) and temperature (4%), and negatively to 1‐week lagged mite density (20%) and precipitation (6%) for time‐series analysis. For experimental addition of water, mite growth rate was related positively to current mite density (44%) and temperature (5%), and negatively to 1‐week lagged density (11%). Results differed from the Hairston et al. (1960) model predictions but were consistent with a bottom‐up view that springtail and mite populations were regulated intrinsically by competition for food and secondarily by temperature as a function of reproduction.

Changes in trophic abundance of soil arthropods along a grass-shrub-forest gradient

Ecological theory suggests that along productivity gradients, abundances of organisms within trophic levels will increase in a stepwise pattern from producers to consumers. To test this theory I investigated changes in abundance of soil arthropods at three trophic levels: microphytophages, represented by Collembola, predacious mites (Acari) that feed on Collembola, and three groups of macroarthropods (spiders, ants, and centipedes) that were observed to feed on mites. Changes in abundance were monitored along a gradient in vegetation structure from grass to shrub to forest in the Canadian prairies. I controlled for temporal variation in abundance among years and surveys within a year. As predicted, (i) numbers of Collembola did not change with increases in productivity; (ii) mite numbers were greatest in the shrublands; and (iii) numbers of macroarthropod predators increased from grassland to shrubland, and there was a nonsignificant increase in numbers of spiders and centipedes in forest habitat. Contrary to predictions, macroarthropod numbers were not significantly greater in forest habitat, and ant numbers actually declined. Possible explanations for the lack of increase in macroarthropod predator abundance in the forest habitat with the greatest productivity include decreased ground-level humidity and greater abundance of macroarthropod predators and parasites in forest environments.

Changes in trophic abundance of soil arthropods along a grass-shrub-forest gradient

Changes in trophic abundance of soil arthropods along a grass-shrub-forest gradient

Response of soil invertebrates to reduced tillage systems established on a clay loam soil

The response of both the cryptozoic macroarthropod community (large soil invertebrates that live and/or hide on the soil surface) and soil micro and meso-arthropods (Acarina and Collembola) is described with respect to abundance (number of individuals) and richness (number of family groups) when no-till, chisel plow, and ridge-tillage systems were established on a clay loam soil (Typic Haplaquoll) having a previous history of conventional tillage. Except for the September sampling date, in 1988, abundance of cryptozoic fauna was higher in no-till than in conventional tillage: 30 taxonomic families were collected in comparison to 22 for conventional tillage. In 1989, trends in abundance and richness were not consistent in no-till and conventional tillage; chisel plow was similar to no-till; and ridge-tillage was similar to conventional tillage after severe soil disturbance by ridging. In 1988, mean soil arthropod abundance and richness were significantly higher in no-till than in conventional tillage plots from June to the end of August but not in October. In 1989, for no-till, chisel plow, and conventional tillage, there were significant sampling depth and cultivation by depth interaction effects on total soil arthropod abundance.

Influence of agricultural practices on arthropod communities in a vertisol (Martinique)

The influence of human activities on soil arthropods of vertisols was assessed in several plots characterized by different land uses in the south-eastern part of Martinique (French West Indies). Abundance and diversity of soil invertebrate groups and collembolan species were measured in a 40-year-old secondary forest, a 15-year-old fallow, a 4-year-old fallow, a 4-year-old pasture, a 15-year-old pasture and a 20-year-old market-garden. Agricultural practices modified abundance and species distribution of soil arthropods, compared to forest. Arthropod richness (number of taxa present) decreased from forest to market-garden, according to a gradient of intensification of agricultural use (pesticides, tillage, weed control). In the old pasture, the arthropod diversity was lower in spite of a high carbon content. Species richness of Collembola decreased together with plant diversity and water availability.

Consumption patterns, complexity and enrichment in aquatic food chains

The interactions between consumers and prey, and their impact on biomass distribution among trophic levels, are central issues in both empirical and theoretical ecology. In a long-term experiment, where all organisms, including the top predator, were allowed to respond to environmental conditions by reproduction, we tested predictions from 'prey-dependent' and 'ratio-dependent' models. Prey-dependent models made correct predictions only in the presence of strong interactors in simple food chains, but failed to predict patterns in more complex situations. Processes such as omnivory, consumer excretion, and unsuitable prey-size windows (invulnerable prey) increased the complexity and created patterns resembling ratio-dependent consumption. However, whereas the prey-dependent patterns were created by the mechanisms predicted by the model, ratio-dependent patterns were not, suggesting that they may be 'right for the wrong reason'. We show here that despite the enormous complexity of ecosystems, it is possible to identify and disentangle mechanisms responsible for observed patterns in community structure, as well as in biomass development of organisms ranging in size from bacteria to fish.

Post-Fire Arthropod Assemblages in Mediterranean Forest Soils in Israel

The presence of soil micro- and macroarthropod species was surveyed after severe fire in a mixed forest dominated by Aleppo pine on Mt. Carmel, Israel. Arthropods were sampled, and separated into 19 taxa (mainly orders or classes). The effects of 2nd-5th post-fire years, seasons, habitats (burned and unburned) and tree species (pine or oaks) on the relative abundance of soil arthropods were analyzed by linear redundancy analysis. Arthropod distribution along the first axis of the analysis was non-random, so all these factors influenced arthropod community composition. Arthropod composition in the 2nd and 3rd postfire years was different from later years, demonstrating outbreaks of pioneers. After five post-fire years arthropod populations were not completely recovered. Significant seasonal differences in population size were detected, indicating summer, and to lesser extent also winter, as unfavorable periods in that region, as was well demonstrated with Collembola. The resilience of arthropods under burned oaks differed from the arthropods sampled under burned pines. Seven taxa were highly correlated to the unburned zone and included the main microarthropod groups (Collembola, Protura, Acari, and Pauropoda) and Coleoptera, Thysanoptera and Chilopoda. Only two orders showed a distinct association with-the burned zone: Psocoptera and Homoptera; the latter was represented almost solely by specimens of a pioneer species, Rhizoicus sp. (Pseudococcidae).

Vehicle Tracks on High Arctic Tundra: Their Effects on the Soil, Vegetation, and Soil Arthropods

Examination of the effects of vehicle and pedestrian tracks of known age (13 or more years) and intensity of use (single to multiple passages) on vegetation, soil chemistry, soil arthropods, soil thaw characteristics, and small-scale hydrological changes showed clear and inter-related patterns. In general, all tracks, regardless of age, showed small increases in the depth of thaw beneath them (c. 2.8 cm). Tracks were generally depleted of carbon and to a lesser, but significant extent, of potassium and phosphorus. Slight increases in NO 3 , NH 4 , and calcium were noted. Magnesium and total nitrogen seemed unaffected. On all tracks which had suffered multiple passages vegetation cover was significantly reduced. In a few sites where single passages were recorded, cover increased through proliferation of the sedge, Kobresia myosuroides. Abundance of soil arthropods was significantly reduced on tracks, but the diversity was not. In most sites, soil moisture and over-ground water flow did not seem affected. Only in sedge meadows where compression from a single passage resulted in channelling of water, and where multiple passages removed vegetation and initiated gulley erosion, were effects serious.

Soil Arthropod Abundance in Coast Redwood Forest: Effect of Selective Timber Harvest

Soil arthropod communities were surveyed and compared in litter layers of selectively harvested and nonharvested forests of coast redwood, Sequoia sempervirens , to assess impact of a l5-yr selective timber harvest cycle. Abundance of four guilds (microphytophages, panphytophages, macrophytophages, and predators) were estimated from litter samples taken from three forest classes: uncut old growth, mature second growth last harvested before 1920, and selectively harvested forest sampled 14 yr after harvest. Microphytophage and panphytophage abundance did not vary significantly among forest classes. Macrophytophages showed significantly higher abundance in selectively harvested forest, whereas predators showed significantly reduced abundance in selectively harvested forest. Because no significant differences in macrophytophage and predator abundance were found between old growth and mature second growth classes, observed differences are attributed to the selective timber harvest regime. Furthermore, since selectively harvested forest was sampled for arthropods 14 yr after harvest, it appears that the 15-yr cycle is of insufficient duration to allow full recovery of soil arthropod communities from the effect of selective timber harvest. In addition, it is likely that species are at high risk of extinction, based on the striking observation that an entire order, Diplura, was absent from all samples taken from selectively harvested sites. Possible explanations for observed differences in guild abundance and potential implications for long-term maintenance of soil arthropod diversity are discussed.

Decomposition of straw in relation to tillage, moisture, and arthropod abundance in a semi-arid tropical Alfisol

The decomposition of rice straw was studied in relation to straw moisture and the abundance of soil arthropods, such as Acarina, Collembola, and miscellaneous groups dominated by termites [Odontotermes obesus (Rambur) and Microtermes obesi Holmgren], across tillage treatments (no tillage, shallow tillage, and deep tillage) in Alfisols of the semi-arid tropics in India from August 1989 to July 1990. In the straw, across the treatments, Acarina were dominant (>70% of the total arthropods), and Collembola were a minor component. O. obesus and M. obesi foraged straw together under the cover of an earthern sheet. A larger number of arthropods was recorded during the rainy season, but they were either negligible or absent during the dry season. The abundance of arthropods and mass loss of straw was greater in coarse-mesh bags than in the fine-mesh bags. Their abundance was significantly affected by tillage treatments and season (P<0.01). In the beginning, it was significantly greater in the no-tillage and shallow-tillage than in the deep-tillage treatment. The mass loss was 46% of the initial mass during the first 60 days, and more than 90% after 330 days of decomposition. Tillage had a significant effect on mass loss, particularly after 330 days, and the no tillage treatment led to a greater mass loss. Multiple linear regression analysis revealed that the moisture content of the straw and the abundance of arthropods had significantly affected the mass loss in both fine-and coarse-mesh bags across the tillage managements.

Seasonal Abundance of Soil Mites (Acarina) in Two Contrasting Environments

The soils of a secondary regrowth forest plot and an adjoining cassava plot in southwest Nigeria were investigated over an annual cycle to show the seasonal variations in their mite (Acarina) populations. Data on rainfall, soil moisture content, and soil temperature were simultaneously collected. Microenvironmental differences in the two plots were reported to have influenced the densities, age structure, and fluctuation patterns of the mite populations. Like most other arthropods, mostly insects and spiders studied in other tropical environments, the soil mites showed within and between seasonal changes in abundance at both the forest and cassava plots. Two patterns of seasonal fluctuations characterized by a single maximum population density on the one hand and multiple peak populations on the other hand were shown by the mite groups in the forest and cassava plots. Unlike most mite groups whose patterns of fluctuation were similar in the forest and cassava plots, Haplozetes sp., Carabodes sp., Oppia sp., Tectocepheus sp., and Parasitidae were reported to have reacted to the difference in environmental attributes between the forest and the cassava plots by exhibiting different fluctuation patterns between the two plots. The population build-up potential of mites in the cassava plot, especially Haplozetes sp., is discussed. SOIL MITES (ACARINA) are the most abundant forest soil microarthropods (Strickland 1945, Belfield 1956, Lasebikan 1974, Badejo 1982). They have been reported by these workers to account for over 50 percent of the total microarthropod density of forest soils. Being mostly detritivores, they play a very important role in nutrient cycling by increasing the rate of litter breakdown and mixing breakdown products with organic matter in the soil (Edwards et al. 1970). Seasonal differences in the abundance of soil arthropods have been demonstrated by various workers (Salt 1952, Belfield 1956, Davis 1963, Block 1966, Erasmus & Ryke 1970, Niijima 1971, Lasebikan 1975, Usher 1975). These workers reported that microarthropods undergo enormous fluctuations in numbers, these being susceptible to small changes in microenvironment, and that water is the primary factor influencing population size. In the tropics, detailed studies on seasonality of arthropods have been based mostly on insect populations (Bigger 1976; Buskirk & Buskirk 1976; Janzen 1976; Wolda 1977, 1978). Unlike temperate countries, there is no study on fluctuation in mite populations lasting through an annual cycle. The aim of this study was to compare the seasonal changes in the densities of mites in a tropical forest and a cassava plot, with the hypothesis that microenvironmental variations in these contrasting environments influence the fluctuation in the numbers of soil mites. Age structure and fluctuations in mite densities were compared to water availability and temperature conditions in the soil. STUDY SITE AND METHODS This investigation was carried out in a 10 m x 10 m forest plot marked out of a regrowth forest and in an adjoining (separated by a 1 m strip) 10 m x 10 m cassava plot within the Teaching and Research Farm of the Obafemi Awolowo University, Ile-Ife, Oyo State, Nigeria (Lat. 7?29'N, Long. 4?34'E). This farm is about 5 km from the University central campus. This forest is a 20 year old fallow resulting from the traditional shifting cultivation system. The vegetation of the forest plot consisted mainly of trees including Albizia zygia (all plant names after Hutchinson & Dalziel 1954-1972), Cola acuminata, Manihot sp., and Morinda lucida. Prominent among the shrubs were Mimosa invisa and Cnestisferrugiana. The herbs included Chromoleana odorrata, Desmodium gangeticum, Sida acuta, Cassia hirsuta, Panicum maximum, and Mormordica charantia. Plant identification was performed at the Obafemi Awolowo University Herbarium (IFE). In February 1983, the adjoining plot to this forest plot was manually cleared, raked, and burned. Ten rows of heaps were made with each row being 1 m apart. Within each row the heaps were also 1 m apart. Subsequently, cuttings of a sweet variety I Received 30 July 1989, accepted 23 January 1990.

The distribution and abundance of soil arthropods in the Northern Mojave desert

Arthropods were extracted from soil samples taken from around four perennial plant species in Rock Valley, Nevada, from January to December 1974. The pattern of distribution of the arthropods about the shrubs is described and a model has been constructed to estimate population densities and biomasses. Total arthropod densities ranged from 1600 per m2 in July to 12,400 per m2 in December. Total biomass was also lowest in July, 8·7 mg/m2, and reached 37·2 mg/m2 in May. The majority of animals collected belonged to the Acari, and of these the Cryptostigmata and the prostigmatid families, Nanorchestidae and Tydeidae, were most abundant. Seasonal variations in the distribution patterns are discussed.

Patterns of Coleoptera Species Diversity in Contrasting White Pine and Coppice Canopy Communities

The pattern of Coleoptera species diversity in coppice hardwoods and white pine canopy communities was investigated. The information-theory index H(s) and the index D were used to measure diversity. The distribution of individuals within species was measured by using redundancy and evenness indices. Diversity in the coppice was greater than in the white pine. The coppice canopy community followed a seasonal trend in diversity, even- ness and redundancy. Diversity in the white pine community did not follow an apparent seasonal trend. Considerably fewer species and indi- viduals occurred in the white pine, which tended to magnify the impor- tance of the appearance and disappearance of dominant species and thereby to obliterate any seasonal trend in diversity, redundancy and evenness. population level. Very little information is available concerning the structure of canopy insect communities. The intent of this study was to investigate the pattern of Coleoptera species diversity in white pine (Pinus strobus L.) and coppice canopy communities through the use of information-theory indices of diversity. Indices of diversity have been utilized in the study of an array of different communities. Margalef (1957) was perhaps the first to dem- onstrate the use of the information-theory approach to the analysis of natural communities. Subsequently Pielou (1966) examined the ap- plicability of the various information-theory measures of diversity to different types of biological collections. A method for determining the evenness component of diversity was also considered. Wilhm (1967) compared several diversity indices through the analyses of benthic macroinvertebrates and concluded that the information-theory ap- proach provided a suitable means of evaluating community structure. The information-theory approach to community analysis has been found suitable in the study of abundance of soil microarthropods (Hairston 1959), bird species (MacArthur and MacArthur 1961), and arthropods in a 1-year-old field successional community (Rich- ardson 1969), as well as many other natural communities. METHODS AND MATERIALS The present investigation was conducted at the Coweeta Hydro- logic Laboratory in the Appalachian Mountains of western North Carolina. The study areas were located in white pine and coppice watershed catchment basins, which have been designated by the Forest Service as watershed numbers 17 and 13, respectively.