Abundance Of Soil Animals Research Articles

Crushed concrete and biochar: A sustainable solution for vegetated roofs

Besides providing several important ecosystem services, vegetated roofs can provide also ecosystem disservices, such as leaching nutrients that cause eutrophication in adjacent water bodies. Such downsides and limited knowledge on hydrologic performance of vegetated roofs in a cold climate may prevent their wider implementation. Another issue concerns sustainability of materials used in vegetated roofs. A replicated field experiment was run for four years in southern Finland to study the performance of vegetated roof ecosystems with substrates containing crushed lightweight concrete, biochar or crushed brick. All materials were locally sourced and recycled. Nutrient dynamics, soil fauna, vegetation and stormwater management were monitored. Alkaline concrete efficiently reduced phosphorus leaching due to high pH compared with that of a neutral brick substrate. Amending concrete substrate with 20% (v/v) biochar improved retention of nitrogen and in < 20 mm events also rainfall. Vegetation grew equally well in all treatments. The abundance of soil animals, nematodes and enchytraeids, varied markedly over time, driven by changes in substrate moisture. Rainfall was efficiently retained and runoff detained, especially during summer, which is the rainiest season in Finland. We conclude that concrete and biochar as materials used in substrate can provide an effective, innovative and sustainable solution for vegetated roofs.

Vibrational noise from wind energy‐turbines negatively impacts earthworm abundance

Human activities often impact the sensory environment of organisms. Wind energy turbines are a fast‐growing potential source of anthropogenic vibrational noise that can affect soil animals sensitive to vibrations and thereby alter soil community functioning. Larger soil animals, such as earthworms (macrofauna, &gt; 1 cm in size), are particularly likely to be impacted by the low‐frequency turbine waves that can travel through soils over large distances. Here we examine the effect of wind turbine‐induced vibrational noise on the abundance of soil animals. We measured vibrational noise generated by seven different turbines located in organically‐farmed crop fields in the Netherlands. Vibratory noise levels dropped by an average of 23 ± 7 dB over a distance of 200 m away from the wind turbines. Earthworm abundance showed a strong decrease with increasing vibratory noise. When comparing the nearest sampling points in proximity of the wind energy turbines with the points furthest away, abundance dropped on average by 40% across all seven fields. The abundance of small‐sized soil animals (mesofauna, &lt; 10 mm in size) differed between crop fields, but was not related to local noise levels. Our results suggest that anthropogenic vibratory noise levels can impact larger soil fauna, which has important consequences for soil functioning. Earthworms, for instance, are considered to be crucial ecosystem engineers and an impact on their abundance, survival and reproduction may have knock‐on effects on important processes such as water filtration, nutrient cycling and carbon sequestration.

Soil arthropod communities are not affected by invasive Solidago gigantea Aiton (Asteraceae), based on morphology and metabarcoding analyses

Invasive plants form new ecological links with native biota that can affect soil animals. Giant goldenrod (Solidago gigantea Aiton) of the Asteraceae family originates in North America, but it is an invasive plant elsewhere in the world. We studied the belowground arthropod communities of invasive S. gigantea and native vegetation at three sites near Moscow, Russia. Molecular techniques allow for quick identification of the community composition but provide little information on the abundance of soil animals and should be verified by classical taxonomy methods. Thus, we identified soil arthropods using metabarcoding and morphological identification. The number of arthropod families identified by the two methods was comparable (53 and 56, respectively), with a significant correlation in the number of families detected in individual samples based on morphological and metabarcoding approaches. The structure of the belowground arthropod community was subtly different between the goldenrod and control sites. A goldenrod transplant experiment was designed to control the random factors that created site-specific variation. After one year, the abundance and diversity of soil arthropods remained the same in sites with transplanted goldenrod and the control plots, leading to the conclusion that invasive S. gigantea does not affect soil arthropod communities in this region.

Alkaline habitat for vegetated roofs? Ecosystem dynamics in a vegetated roof with crushed concrete-based substrate

Using local and recycled materials is a sustainable way to establish a vegetated roof. In order to understand how the roof ecosystem functions and returns ecosystem services, it is important to study vegetation, soil organisms and runoff quality. We established a vegetated roof experiment based on a substrate containing lightweight crushed concrete, an alkaline side product from a concrete factory, mixed with compost. This five-year experiment in southern Finland tested how planting method (pre-grown vegetation mats vs. pot planting), compost content (20% vs. 40%, fresh volume), and substrate depth affect the cover and diversity of plants, the abundance of soil animals and the quality of runoff. Although the substrate had a high pH (7.3–11.8), many vascular plants were able to survive and establish viable populations. The planting method had a strong effect on plant diversity and the cover of individual species because the vegetation mats became dominated by the invasive, non-native Phedimus hybridus. Establishment with pot plants in turn provided bare ground that was colonised by spontaneous non-invasive species. This resulted in higher diversity, and a more even distribution of species. The amount of compost had only a weak impact on vegetation, whereas high pH generally reduced plant abundance and diversity. The concentrations of total phosphorus and total nitrogen in runoff were low as compared to values reported from many other vegetated roofs, were not affected by compost content and decreased over time. In summary, the high-pH substrate based on recycled materials is an environmentally responsible choice, suitable for a wide variety of plants, even rare and endangered species.

Effects of grazing on the composition of soil animals and their decomposition function to Stipa grandis litter in Inner Mongolia typical steppe, China.

Grazing has been considered to be an important factor determining the composition of soil animals and decomposition of leaf litter in grassland ecosystem. Sampling plots were selected in ungrazed grassland, grazed grassland and sandy land. Litter bags were used to compare the changes of physicochemical properties of Stipa grandis litter and the composition of soil fauna in the process of the litter decomposition in Baiyinxile, Inner Mongolia, since 2010 to 2012. A total number of 67056 soil animals were captured, belonging to five phyla and eight classes, including 23 families of mites and 19 families of insects. After 780 days' decomposition, the loss of the organic matter of S. grandis litter was from 92.5% to 40.0% in the ungrazed grassland, and to 41.3% in the grazed grassland, with no significant difference observed. However, there was a significant difference (P<0.05) between the ratio of litter residues of the ungrazed grassland (50.0%) and that of the grazed grassland (23.0%). The abundance of soil animals in the residual litters was significantly decreased in the grazed grassland compared to the ungrazed grassland. When the litter was moved into the sandy land, the decomposition rate of organic matter in the residual litter was not significant changed but the ratio of litter residue declined significantly, and the composition of mite community in the resi-dual litter changed significantly. Our results illustrated that grazing activity could affect the composition and abundance of soil fauna in temperate grassland, but slightly influenced the decomposition of organic matter. Therefore, soil animals had relatively weak direct effects on the decomposition of litter in this semi-arid region.

Diversity and Abundance of Soil Animals as Influenced by Long-Term Fertilization in Grey Desert Soil, China

The relationship between soil fauna and different fertilizer management practices is of growing concern. The aim of this research was to investigate the response of soil fauna to fertilization regimes, to explore the relationships among the community of soil animals, soil moisture and crop yields. The application of organic fertilizers (i.e., sheep manure or crop residues) increased crop yields and promoted the number of individuals and species of soil fauna owing to the exogenous organic matter that fertilizers provided for the survival and development of soil fauna. Furthermore, the treatments that applied sheep manure (i.e., sheep manure only or nitrogen, phosphorus, potassium and sheep manure plus) were significantly beneficial for increasing crop yields and diversity of soil fauna compared to treatments with crop residues returned (i.e., crop residues returned only or nitrogen, phosphorus, potassium and crop residues returned to the field) (p &lt; 0.05) due to the response of soil fauna to diverse exogenous nutrients and the effect of soil fertility. Therefore, the finding that soil fauna abundance is significantly positively correlated with soil moisture and crop yield may mean the effects of fertilizer applications on soil animals were partly masked by the soil moisture and crop yield.

Genotypic diversity of an invasive plant species promotes litter decomposition and associated processes

Following studies that showed negative effects of species loss on ecosystem functioning, newer studies have started to investigate if similar consequences could result from reductions of genetic diversity within species. We tested the influence of genotypic richness and dissimilarity (plots containing one, three, six or 12 genotypes) in stands of the invasive plant Solidago canadensis in China on the decomposition of its leaf litter and associated soil animals over five monthly time intervals. We found that the logarithm of genotypic richness was positively linearly related to mass loss of C, N and P from the litter and to richness and abundance of soil animals on the litter samples. The mixing proportion of litter from two sites, but not genotypic dissimilarity of mixtures, had additional effects on measured variables. The litter diversity effects on soil animals were particularly strong under the most stressful conditions of hot weather in July: at this time richness and abundance of soil animals were higher in 12-genotype litter mixtures than even in the highest corresponding one-genotype litter. The litter diversity effects on decomposition were in part mediated by soil animals: the abundance of Acarina, when used as covariate in the analysis, fully explained the litter diversity effects on mass loss of N and P. Overall, our study shows that high genotypic richness of S. canadensis leaf litter positively affects richness and abundance of soil animals, which in turn accelerate litter decomposition and P release from litter.

Assessment of Ecological Risks at Former Landfill Site Using TRIAD Procedure and Multicriteria Analysis

Old industrial landfills are important sources of environmental contamination in Europe, including Finland. In this study, we demonstrated the combination of TRIAD procedure, multicriteria decision analysis (MCDA), and statistical Monte Carlo analysis for assessing the risks to terrestrial biota in a former landfill site contaminated by petroleum hydrocarbons (PHCs) and metals. First, we generated hazard quotients by dividing the concentrations of metals and PHCs in soil by the corresponding risk-based ecological benchmarks. Then we conducted ecotoxicity tests using five plant species, earthworms, and potworms, and determined the abundance and diversity of soil invertebrates from additional samples. We aggregated the results in accordance to the methods used in the TRIAD procedure, conducted rating of the assessment methods based on their performance in terms of specific criteria, and weighted the criteria using two alternative weighting techniques to produce performance scores for each method. We faced problems in using the TRIAD procedure, for example, the results from the animal counts had to be excluded from the calculation of integrated risk estimates (IREs) because our reference soil sample showed the lowest biodiversity and abundance of soil animals. In addition, hormesis hampered the use of the results from the ecotoxicity tests. The final probabilistic IREs imply significant risks at all sampling locations. Although linking MCDA with TRIAD provided a useful means to study and consider the performance of the alternative methods in predicting ecological risks, some uncertainties involved still remained outside the quantitative analysis.

Effects of Human Trampling on Populations of Soil Fauna in the McMurdo Dry Valleys, Antarctica

Antarctic ecosystems are often considered nearly pristine because levels of anthropogenic disturbance are extremely low there. Nevertheless, over recent decades there has been a rapid increase in the number of people, researchers and tourists, visiting Antarctica. We evaluated, over 10 years, the direct impact of foot traffic on the abundance of soil animals and soil properties in Taylor Valley within the McMurdo Dry Valleys region of Antarctica. We compared soils from minimally disturbed areas with soils from nearby paths that received intermediate and high levels of human foot traffic (i.e., up to approximately 80 passes per year). The nematodes Scottnema lindsayae and Eudorylaimus sp. were the most commonly found animal species, whereas rotifers and tardigrades were found only occasionally. On the highly trampled footpaths, abundance of S. lindsayae and Eudorylaimus sp. was up to 52 and 76% lower, respectively, than in untrampled areas. Moreover, reduction in S. lindsayae abundance was more pronounced after 10 years than 2 years and in the surface soil than in the deeper soil, presumably because of the longer period of disturbance and the greater level of physical disturbance experienced by the surface soil. The ratio of living to dead Eudorylaimus sp. also declined with increased trampling intensity, which is indicative of increased mortality or reduced fecundity. At one site there was evidence that high levels of trampling reduced soil CO(2) fluxes, which is related to total biological activity in the soil. Our results show that even low levels of human traffic can significantly affect soil biota in this ecosystem and may alter ecosystem processes, such as carbon cycling. Consequently, management and conservation plans for Antarctic soils should consider the high sensitivity of soil fauna to physical disturbance as human presence in this ecosystem increases.

Plant litter decomposition influenced by soil animals and disturbance in a subtropical rainforest of Taiwan

Soil fauna has been postulated as one of the paramount determinants of decomposition in the humid tropics. However, its effect on litter decomposition has only been demonstrated in few forest sites in Central America. In addition, landslide is a common disturbance associated with heavy rainfall brought by tropical cyclones in the tropics and can potentially alter abundance and structure of soil animals and thus affect litter decomposition. In this study, we examined the effect of soil animals on litter decomposition in an Asian subtropical monsoon forest and compared the animal effects in landslide-disturbed (2 years old) and undisturbed sites. Animal exclusion by naphthalene treatment significantly reduced the density and diversity of litterbag animals and slowed down the rate of decomposition in both landslide-disturbed and undisturbed sites. However, density (per unit area) and diversity of the litter animals and litter decomposition rate did not differ between the landslide-disturbed and undisturbed sites for both control and animal-excluded treatments. Our data suggest that the abundance of soil animals is not limited by litter mass. Furthermore, soil fauna recover quickly from landslides, and fauna's facilitative effect on litter decomposition is not altered after their recovery.

Belowground responses by AM fungi and animal trophic groups to repeated defoliation in an experimental grassland community

We tested a hypothesis that the effects of defoliation on plants and soil organisms vary with the number of successive defoliations. We established a 23-week greenhouse experiment using replicated grassland microcosms that were composed of three plant species, Trifolium repens, Plantago lanceolata and Phleum pratense, growing together in grassland soil with a diverse soil community. The experiment consisted of two treatment factors-defoliation and harvest time-in a fully factorial design. The defoliation treatment had two levels, i.e. no trimming and trimming of plants every 2 weeks, and the harvest time five levels, i.e. harvests after 1–3, 5 and 7 trimmings. Shoot production (trimmed plus harvested shoot mass), harvested shoot and root mass and root N and C concentrations increased with time but were reduced by defoliation. Colonization rates of arbuscular mycorrhizal (AM) fungi decreased with time in T. repens roots but were enhanced by defoliation, whereas AM colonization rates in P. pratense roots were not affected by harvest time or defoliation. The abundance of bacterivorous and fungivorous nematodes decreased and that of herbivorous and predatory nematodes increased with time, while the abundance of omnivorous nematodes and detritivorous enchytraeids varied in time without a linear trend. Defoliation had no effect on fungivores and predators but increased the abundance of bacterivores. Defoliation also increased the abundance of herbivores, omnivores and detritivores after 2 trimmings and that of omnivores and detritivores after 5 trimmings, but had a negative effect on omnivores after 3 trimmings and on herbivores after 7 trimmings. Among nematode genera, some deviation from the trophic group responses existed: for instance, defoliation reduced the abundance of bacterivorous Acrobeloides spp. and did not affect the abundance of herbivorous Filenchus spp. and Paratylenchus spp. Our results show that the effects of defoliation on plants, AM fungi and some soil animal trophic groups may remain constant all the way through several defoliations, whereas other animal trophic groups may have different and even opposite responses to defoliation depending on the length of the defoliation period before monitoring. This shows how separate studies with defoliation periods of different length can produce contradictory results of the effects of defoliation on the abundance of soil animals.

Nest mounds of red wood ants (Formicaaquilonia): hot spots for litter-dwelling earthworms.

A previously undocumented association between earthworms and red wood ants (Formicaaquilonia Yarr.) was found during an investigation of the influence of wood ants on the distribution and abundance of soil animals in boreal forest soil. Ant nest mounds and the surrounding soil of the ant territories were sampled. The ant nest mound surface (the uppermost 5-cm layer) harboured a much more abundant earthworm community than the surrounding soil; the biomass of the earthworms was about 7 times higher in the nests than in the soil. Dendrodrilusrubidus dominated the earthworm community in the nests, while in soils Dendrobaenaoctaedra was more abundant. Favorable temperature, moisture and pH (Ca content), together with abundant food supply (microbes and decomposing litter) are likely to make a nest mound a preferred habitat for earthworms, provided that they are not preyed upon by the ants. We also conducted laboratory experiments to study antipredation mechanisms of earthworms against ants. The experiments showed that earthworms do not escape predation by avoiding contact with ants in their nests. The earthworm mucus repelled the ants, suggesting a chemical defence against predation. Earthworms probably prevent the nest mounds from becoming overgrown by moulds and fungi, indicating possible mutualistic relationships between the earthworms and the ants.

The decomposition of dead organic matter in natural ecosystems and field in forest steppe zone — The role of separate factors

Field experiments with the decomposition of dead organic matter in various ecosystems (unmown steppe, oak forest, barley field, ploughed field) indicated that soil macro- and mesofauna had a variable but generally significant effect on litter decomposition. Decomposition rate was higher in forest than in open ecosystems owing to better hydrothermical regime. Decomposition rate in open ecosystems was the highest in the ploughed field and in the steppe. Decomposition rate in barley field was lower than in the above mentioned ecosystems. The decomposition in ploughed field was provided by a high activity of soil microorganisms because the abundance of soil animals was insignificant. Freilandversuche zur Zersetzung abgestorbener organischer Substanz in verschiedenen Ökosystemen (ungemähte Steppe, Eichenwald, Gerstenfeld, Ackerland) deuten darauf hin, daß die Bodenmakro- und -mesofauna einen unterschiedlichen, aber im allgemeinen bedeutenden Einfluß auf die Zersetzungsrate ausübt. Die Geschwindigkeit des Abbaus war im Wald höher als in den offenen Ökosystemen, bedingt durch ein besseres hydrothermisches Regime. Bei den offenen Ökosystemen lag die Zersetzungsrate im Ackerland höher als in der Steppe. Im Gerstenfeld wurden die niedrigsten Werte beobachtet. Der Abbau der organischen Substanz im Ackerland war vor allem bedingt durch eine hohe mikrobielle Aktivität; die Bodentiere spielten hier nur eine untergeordnete Rolle.

Agriculture and the abundance of soil animals in the Western Australian wheatbelt

Agriculture and the abundance of soil animals in the Western Australian wheatbelt