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The aim of this study was to apply the method of structural equation modeling using latent variables (constructs) with multi-indicators to test hypothesized interaction models among functional groups of fauna and attributes of lit...
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The aim of this study was to apply the method of structural equation modeling using latent variables (constructs) with multi-indicators to test hypothesized interaction models among functional groups of fauna and attributes of litter-soil system in cacao agroforests in the south of Bahia, Brazil. The hypothesized structural model was composed of four constructs: the litter-attributes, litter-fauna, soil-attributes, and soil-fauna. The models tested were able to distinguish between the direct and indirect relationships of the faunal groups and attributes of litter soil system. The results have shown that the interconnection theory between fauna and attributes of litter-soil system should be presented in more than one structural equation model. The models built from the re-specifications showed a strong theoretical base and data fitted, well representing the fauna as a latent variable (construct) theory within the litter-soil system of cacao agroforests. The overall fit of the hypothesized models highlighted the theoretical plausibility of complex interconnection between soil and litter fauna. Both are influenced by the attributes of their niches. Litter-attributes construct composed only by the indicators lignin, cellulose and polyphenols showed a recalcitrant predominant nature. This low litter nutritional quality would negatively affect the faunal groups therein. The negative relation between litter-attributes and soil-attributes suggest that low-quality litter contributed little to the improvement of soil fertility, particularly related to the level of acidity. The negative relationship between soil-attributes and soil-fauna shows that highly acid and low fertility soils would promote some restriction on the activity of soil fauna groups. The structural equation modeling with latent variables proved to be a suitable tool for the understanding of the complexity of the relationships between faunal groups within the tested litter-soil system, indicating how the changes in a latent composition would affect other latents. It important to mention that when the approach is about organisms in the litter-soil system, caution is advised when trying, in a mechanistic way, to determine the factors influencing the interconnection of these organisms with their niches, due to the inherent heterogeneity of both litter and soil.
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Global fire regimes are shifting due to climate and land use changes. Understanding the responses of belowground communities to fire is key to predicting changes in the ecosystem processes they regulate. We conducted a comprehensi...
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Global fire regimes are shifting due to climate and land use changes. Understanding the responses of belowground communities to fire is key to predicting changes in the ecosystem processes they regulate. We conducted a comprehensive meta-analysis of 1634 observations from 131 empirical studies to investigate the effect of fire on soil microorganisms and mesofauna. Fire had a strong negative effect on soil biota biomass, abundance, richness, evenness, and diversity. Fire reduced microorganism biomass and abundance by up to 96%. Bacteria were more resistant to fire than fungi. Fire reduced nematode abundance by 88% but had no significant effect on soil arthropods. Fire reduced richness, evenness and diversity of soil microorganisms and mesofauna by up to 99%. We found little evidence of temporal trends towards recovery within 10 years post-disturbance suggesting little resilience of the soil community to fire. Interactions between biome, fire type, and depth explained few of these negative trends. Future research at the intersection of fire ecology and soil biology should aim to integrate soil community structure with the ecosystem processes they mediate under changing global fire regimes.
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Soil respiration from microcosms contaminated with pentach- lorophenol, 2-ethanolhexanoate, creosote, CuSO_4, and benomyl was measured in order to evaluate usefulness of soil microcosms and microbial respiration rate monitoring as...
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Soil respiration from microcosms contaminated with pentach- lorophenol, 2-ethanolhexanoate, creosote, CuSO_4, and benomyl was measured in order to evaluate usefulness of soil microcosms and microbial respiration rate monitoring as a toxicity test in soils with high organic matter content. Coniferous forest soil and its organisms were used as test objects, in addition, how a short- term low temperature period including frost affects respiration dynamics in stressed soils was studied, i.e., whether contaminants reduce resistance of the community to other (also natural) stres- ses. In addition, at the end of the experiment, effects of con- taminants on faunal and microbial community structures were analyzed.
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This paper reports the results of a study on the Collembola fauna of 5 different altitudinal sites of Darjeeling Himalayas of West Bengal, India. The species recorded were: Willowsia brahmides, Lepidocrystrus sp., Entomobrya kali,...
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This paper reports the results of a study on the Collembola fauna of 5 different altitudinal sites of Darjeeling Himalayas of West Bengal, India. The species recorded were: Willowsia brahmides, Lepidocrystrus sp., Entomobrya kali, Pseudosinella sp., Tomocerus petalopines, T. mitrai, T. serratospinus, Salina indica, Dicranocentroides indica, D. salmoni, Cyphoderus simulans, Isotoma trispinata, Folsomia alpha, Isotumuras sp., Hypogastrura sp., Willemia sp., Xenylla sp., Neanura corallina, N. intermedia and N. pudibunda. Results revealed that Collembola species decreased with an increase in altitude..
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Abstract The conversion of natural grasslands to cultivated pastures can have a significant impact on the composition and structure of soil macro‐ and mesofauna groups, compromising the resilience of these organisms and the ecosy...
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Abstract The conversion of natural grasslands to cultivated pastures can have a significant impact on the composition and structure of soil macro‐ and mesofauna groups, compromising the resilience of these organisms and the ecosystem services they provide. We studied the responses of these groups to increasing levels of soil disturbance across a gradient of four land management practices: Natural grassland (NG), Improved‐natural grassland (IG), Perennial‐cultivated pasture (PP), and Annual‐cultivated pasture (AP). The NG area had a higher abundance of macrofauna, greater dominance of certain groups, particularly Isoptera, and a lower abundance of mesofauna. On the other hand, the IG area had a higher abundance and diversity of macro‐ and mesofauna, with a lower dominance of specific groups. The PP area had a higher abundance of Coleoptera, Oligochaeta, and Hemiptera, whereas the AP area, despite soil disturbance, showed a higher abundance of mesofauna, particularly mites, Collembola, and Enchytraeidae, but lower diversity. Different grassland management practices have significantly altered the composition and structure of macro‐ and mesofauna groups, resulting in high dissimilarity between communities. We recommend IG as a more productive and sustainable alternative to the total replacement of natural vegetation (NG) with intensified converted pastures (PP and AP), as it maintains soil fauna diversity and ecosystem services.
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Soil fauna is an essential community in forest ecosystems; yet, the role of these organisms in soil total CO2 emission is still unclear, partly because of the lack of effective measurement methods, especially in field situ conditi...
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Soil fauna is an essential community in forest ecosystems; yet, the role of these organisms in soil total CO2 emission is still unclear, partly because of the lack of effective measurement methods, especially in field situ conditions. This study investigated the soil fauna community in Moso bamboo (Phyllostachys pubescens) stands in subtropical China, the faunal contribution to soil total respiration, and the effects of different methods for repelling soil fauna. Three methods to repel soil fauna were tested, including naphthalene application (NT sites), electric steel bars (SET sites), and the combination of naphthalene and electric steel bars (NET sites). Control sites (NTC sites) had no treatment. The results showed that naphthalene, electric steel bars, and a combination of naphthalene and electric steel bars all are powerful in excluding soil fauna individual numbers (INs) (F = 48.65, P < 0.05), but none of them could change the numbers and the composition of soil fauna groups significantly (S = 0.889-1.00 and W = 0.833-0.960). The mean soil fauna respiration was measured at approximately 0.178 mu mol m(2) s(-1); the mean faunal contribution to soil total respiration was 4.02 % at SET sites, 4.11 % at NT sites, and 5.51 % at NET sites; and the mean-reduced fauna numbers were 71.46, 79.13 and 84.84 %, with the mean soil CO2 flux losses (MRL) increased. Mean soil respiration losses (MRLs) were significantly related to H' (R-2 = 0.838, P < 0.004) and IN (R-2 = 0.810, P < 0.004) in SET, NT, and NET. The results suggested that the method of the combined naphthalene and the electric steel bars were shown to be reliable for the exclusion of soil fauna and the estimation of soil fauna respiration in field measurement.
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The fertility of most tropical soils depends on the level of its organic matter which serves as the reservoir for most plant nutrients and food for organisms in the topsoil. Soil fauna plays a major role in the transformation proc...
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The fertility of most tropical soils depends on the level of its organic matter which serves as the reservoir for most plant nutrients and food for organisms in the topsoil. Soil fauna plays a major role in the transformation processes by which plant nutrients are released from soil organic matter. Most of the soils in south-western Nigeria are dominated by low activity kaolinitic clay, generally low in plant nutrient buffering capacity, and easily depleted. As biological property of the soil, faunal population have not been greatly related to the chemical properties and explored as parameter in assessing the fertility of the soil. Though soil microarthropod populations are comparatively lower in tropical soils, the few studies on this group of soil fauna has demonstrated their significant influence on the rates of nutrient turnover. Studies aimed at determining relationships between microarthropod taxa and soil fertility parameters in south-western Nigeria reveal their potential in management of soil for sustainable crop production. In a study involving soils from eight different land-use management, microarthropod population correlated with soil organic carbon, available P and exchangeable cations, and nutrient uptake depending on their taxa. Results also indicated that microarthropod activity could influence P sorption characteristics of the topsoil.
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One of the challenges of research in soil ecology is to assess the impact of tillage managements on soil invertebrates. It is known that tillage practices change soil water content, temperature, the degree of mixing of crop residu...
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One of the challenges of research in soil ecology is to assess the impact of tillage managements on soil invertebrates. It is known that tillage practices change soil water content, temperature, the degree of mixing of crop residues within the soil matrix and the physico-chemical environment for soil organisms. The present study tested whether no-tillage (NT) or a conventional tillage (CT) of a cereal (durum wheat; Triticum durum) field in a semi-arid zone of northwestern Tunisia could improve the biological activity and diversity of soil invertebrates, especially arthropod and earthworm communities.The experiment was conducted in January 2000 at two different sites (Mahasse/Kef Governorate and Krib/Siliana Governorate). Soils (Brunisols, isohumic or fersialitic soil) were silt/clay in Mahessen and sand/clay in Krib. After three and four years, soil fauna was sampled with two methods (quadrat and pitfall trap) over 7 months for the last two growing seasons (200212003 and 200312004). We hypothesized that: (i) soil fauna richness, abundance and diversity would be lower in CT soils than in NT soils and (ii) the move from CT to NT may improve the soil biological component under semi arid conditions.380 invertebrates (37 species) and 309 invertebrates (24 species) were collected by quadrat and pitfall trap methods, respectively. NT greatly enhanced the species richness (from 26 species in CT to 34 species in NT) and abundance (from 61 individuals in CT to 319 individuals in NT) of soil invertebrates with quadrat method. Only abundance was significantly enhanced with pitfall trap method (from 78 individuals in CT to 235 individuals in NT). So, abundance, species richness and diversity of soil arthropods were significantly higher(P < 0.05)with NT than with CT. Soil fauna patterns showed that management mode affected also the abundance of earthworm community. These findings confirm our first hypothesis.Predators (mostly Carabidae), detritivore (especially: Formicidae, Dolicoderidae, Lumbricidae) and herbivore (represented here by Julidae, Pyrrhochridae and some Scarabaeidae) were significantly (P < 0.05) more abundant with NT than with CT. The biological index V (index which compares the relative increase or decrease of the population density between the two tillage modes) showed that all major taxonomic groups were extremely inhibited by CT, confirming our second hypothesis.So, NT seems to be beneficial to biological soil component where it favoured the establishment of diverse soil communities than did CT in durum wheat cropped field. Furthermore, soil fauna may enhance crop-residues decay processes
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Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River, Chi...
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Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River, Chian. Results showed that Hymenoptera, Araneae and Collemboal were the dominant groups Of soil animals in the plots studied. The numbers of groups and individuals and density of soil animals in the Dry red soil series were higher than those in the Vertisol series, and the numbers of individuals and density of Soil animals decreased with the degree of sol degradation.
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