Soil fauna Research Papers - Academia.edu (original) (raw)

The effect of a topoclimatic gradient on soil nematode communities was investigated in the Israeli Judean Desert. Four locations along a 35 km gradient, from an elevation of 650 m above sea level with 620 mm rainfall to a –60 m relative... more

The effect of a topoclimatic gradient on soil nematode communities was investigated in the Israeli Judean Desert. Four locations along a 35 km gradient, from an elevation of 650 m above sea level with 620 mm rainfall to a –60 m relative to sea level with a rainfall below 110 m, were studied: Givat Yearim, Maale Adumim, Mishor Adumim and Kalia. Monthly soil samples were collected between January 1994 and December 1995. Thirteen nematode families and 17 genera were observed. Cephalobus, Heterocephalobus, Aphelenchoides, Tylenchus, Dorylaimus and Eudorylaimus were found to be the dominant genera. Ecological measurements of soil nematode community structure, diversity, and maturity indices were assessed, and comparisons between four locations and four seasons were made. Significant differences in the total numbers of nematodes were found between the locations (p < 0.01) and seasons (p < 0.05), where Givat Yearim > Maale Adumim > Mishor Adumim > Kalia, winter > spring > autumn > summer. Bacterivores were found to be the most abundant trophic group across locations and seasons, with a mean relative abundance of 55.0%. The densities of bacterivores, plant parasites and omnivores-predators during the winter season exhibited similar trends at all four locations, with Givat Yearim > Maale Adumim > Mishor Adumim > Kalia. None of the ecological indices were significantly different between locations. However, the maturity index (MI), trophic diversity (TD) and Simpson diversity (SI) exhibited significant differences between seasons.

Crop residue mulching combined with zero tillage and crop rotation, known as conservation agriculture (CA), is being promoted as an alternative system to revert soil degradation in maize-based farming in the central highlands of Mexico.... more

Crop residue mulching combined with zero tillage and crop rotation, known as conservation agriculture (CA), is being promoted as an alternative system to revert soil degradation in maize-based farming in the central highlands of Mexico. The goal of this paper was to determine the effects of CA vs. conventional tillage systems on soil quality, with a special focus on the role of earthworms in affecting the soil structure morphology, and on crop yield. For the conventional tillage system, the effect of crop residue retention (CONV + RES) was also compared to the conventional farmers’ practice (residues removed; CONV). CA resulted in four times higher earthworm abundance when compared to CONV. Residue retention per se (CONV + RES) did not favor earthworm abundance. In all cases the earthworm community was dominated by exotic species. CA increased total N and soil organic C concentrations relative to CONV, but only at 0–5 cm soil depth. Nevertheless, the more pronounced vertical stratification of soil organic carbon content under CA favored soil surface aggregation and aggregate stability as expressed by the aggregate mean weight diameter after dry sieving (MWDds = 2.6 mm for CA and 1.6 mm for CONV) and wet sieving (MWDws = 0.9 mm and 0.6 mm, respectively). Also, CA improved topsoil water stable macroaggregation (WSA = 415 mg g−1) when compared to CONV (251 mg g−1). Residue retention within conventional tillage (CONV + RES) led to small increases in topsoil aggregate stability (i.e. MWDds and WSA). Soil structural improvements were accompanied by a higher direct surface water infiltration. Micromorphological analysis of thin sections indicated a loose and highly biogenic soil microstructure in CA, whereas CONV was characterized by a physicogenic microstructure, despite similar soil bulk densities (SBD). SBD is thus a poor indicator of soil physical quality when comparing different tillage systems. Redundancy analysis illustrated that CA resulted in improvement in most parameters related to soil quality, especially at the soil surface, but significant yield increases were recorded only in 2004. CONV + RES lead to marginal improvements in soil quality with no yield increases.

Terrestrial ecologists and soil modelers have traditionally portrayed the inhabitants of soil as a black box labeled as “soil fauna” or “decomposers or detritivores” assuming that they just merely recycle the deposited dead plant... more

Terrestrial ecologists and soil modelers have traditionally portrayed the inhabitants of soil as a black box labeled as “soil fauna” or “decomposers or detritivores” assuming
that they just merely recycle the deposited dead plant material. Soil is one of the most diverse habitats on Earth and contains one of the most diverse assemblages of living organisms; however, the opacity of this world has severely limited our understanding of their functional contributions to soil processes and to ecosystem resilience. Traditional
taxonomy, based on morphological and anatomical aspects, is becoming replaced by rapid processing molecular techniques (e.g., with marker gene-based approaches). However,
this may be impracticable in many ecological studies and consequently, the majority of the current knowledge, still contributes little to our understanding of their role
in ecosystem functioning. Over the years, different workers have produced several “functional classifications” based on the body width, feeding regime, certain behavioral and reproductive aspects and ecological niches of soil organisms. Unfortunately, the information available is severely restricted to “major” groups. A better physiological and metabolic understanding of when and how a complex community of soil organisms access nutrients, alter their environment and in turn, affect soil processes, will allow a more realistic quantitative evaluation of their ecological roles in the biogeochemical cycles. Here, I review the applicability of the available approaches, highlight future research challenges
and propose a dynamic conceptual framework that could improve our ability to solve this functional puzzle.

The sustainability of rice production systems globally is intricately related to the chemistry, physics and biology of rice soils – with basic properties differing considerably in wet/dry land soils, tropical/temperate areas or even with... more

The sustainability of rice production systems globally is intricately related to the chemistry, physics and biology of rice soils – with basic properties differing considerably in wet/dry land soils, tropical/temperate areas or even with the soil surface or rhizosphere niche of the field. Rice fields represent unique aqua-terrestrial ecosystems in which the tremendous diversity of soil microbes, soil fauna and plants – ranging in function from nitrogen fixers, nitrifiers, methanogens, methane oxidizers, phosphate-dissolving microbes, sulfur oxidizers to catabolizers of pesticides is observed. This diversity is inclusive of bacteria, cyanobacteria, archaea, planctomycetes and β-proteobacteria, besides the increasing members of endophytes associated. The complexity and dynamic nature of this ecosystem requires in-depth investigations of the tripartite interactions among plants, microbes and the soil–water environment. This needs to be complemented with studies on the ecological compartmentalization due to diffusion gradients of nutrients and gases, which is of extreme significance in the current scenario of problems associated with greenhouse gas emissions from agricultural areas, especially rice paddies. This article provides an overview of the interactions between the microflora and crop, with emphasis on nutrient transformations in the rhizosphere, so as to develop effective and efficient environmentally sustainable strategies for this crop.

We have reviewed the responses of soil fauna to increased concentrations of atmospheric CO2 and the consequent climate change. These will affect several attributes of animal populations and communities including their density, biomass,... more

We have reviewed the responses of soil fauna to increased concentrations of atmospheric CO2 and the consequent climate change. These will affect several attributes of animal populations and communities including their density, biomass, diversity, activity, rates of consumption, life history parameters and migration ability. Changes in the quality and quantity of litter and global warming are the main factors which are expected to modify soil fauna. Although changes have been observed in several attributes of the soil fauna as a consequence of increased concentrations of atmospheric CO2, no general trend which might allow to the prediction of a general pattern of response has been identified. Because of the complexity of the biological mechanisms and the synergetic action of several factors, the few resulting responses reported in the literature are inconclusive. However, some aspects of the situation deserve more attention. These include the consequences of (1) changes in the food resources for soil fauna in the litter layer and in the rhizosphere, (2) the consumption of low quality litter by the macrofauna, (3) the change in life span in response to temperature elevation, (4) the enhancement of earthworm burrowing activity and (5) the changes in community composition arising because of specific differential resistance to adverse conditions.

"In a Mediterranean area of Southern Italy, affected by low- and high-severity experimental fires, burned and unburned soils were analysed, at 245, 364 and 728 days after fire, for total and active fungal mycelium mass, abundance,... more

"In a Mediterranean area of Southern Italy, affected by low- and high-severity experimental fires, burned
and unburned soils were analysed, at 245, 364 and 728 days after fire, for total and active fungal
mycelium mass, abundance, species density and species composition of total, xerotolerant and heatstimulated
culturable fungi, oribatid mites and springtails. Principal Component Analysis was used to
compare species composition of fungal community and faunal groups in burned and unburned plots.
Independently of severity, fire generally caused a decrease in fungal mass, an increase in culturable total,
xerotolerant and heat-stimulated fungi abundance (CFU), and minor changes in fungal species density. In
parallel, fire induced a reduction in abundance and species density of studied faunal groups, generally
correlated with fungal changes, and was consistently associated with the appearance of fungal and faunal
species not present in control. Moreover, qualitative and quantitative changes in fungal community and
faunal groups were recorded in association with sampling time. The results also suggested that the
mosaic of burned and unburned areas, typical of a Mediterranean maquis affected by fire, could promote
biodiversity in soil by favouring the contemporary presence of species typical of disturbed and undisturbed
areas."

We suggest that the strategy evolved by species, or functional groups to control their environment can explain the difference between extended phenotype and accidental engineers. Extended phenotype engineers concentrate their activities... more

We suggest that the strategy evolved by species, or functional groups to control their environment can explain the difference between extended phenotype and accidental engineers. Extended phenotype engineers concentrate their activities on the building of biogenic structures in ...