Soil Moisture Fluctuations Research Articles

Sensitivity of Polygonum aviculare seeds to light as affected by soil moisture conditions.

It has been hypothesized that soil moisture conditions could affect the dormancy status of buried weed seeds, and, consequently, their sensitivity to light stimuli. In this study, an investigation is made of the effect of different soil moisture conditions during cold-induced dormancy loss on changes in the sensitivity of Polygonum aviculare seeds to light. Seeds buried in pots were stored under different constant and fluctuating soil moisture environments at dormancy-releasing temperatures. Seeds were exhumed at regular intervals during storage and were exposed to different light treatments. Changes in the germination response of seeds to light treatments during storage under the different moisture environments were compared in order to determine the effect of soil moisture on the sensitivity to light of P. aviculare seeds. Seed acquisition of low-fluence responses during dormancy release was not affected by either soil moisture fluctuations or different constant soil moisture contents. On the contrary, different soil moisture environments affected seed acquisition of very low fluence responses and the capacity of seeds to germinate in the dark. The results indicate that under field conditions, the sensitivity to light of buried weed seeds could be affected by the soil moisture environment experienced during the dormancy release season, and this could affect their emergence pattern.

Agroforestry management as an adaptive strategy against potential microclimate extremes in coffee agriculture

Current climate change patterns may cause more extreme and variable climates in the future, threatening agricultural productivity in many areas of the world. Because many smallholder, rural farmers depend on subsistence, rainfed agriculture, priorities should be focused on coping mechanisms that protect these farmers from future vulnerabilities. This paper examines one possible adaptive strategy for coffee agriculture. A high (60–80%), medium (35–65%), and low (10–30%) shade coffee site were chosen in the Soconusco region of Chiapas, Mexico. Microclimate and soil moisture data were collected to examine the ability of shade tree cover in an agroforestry system to protect crop plants against extremes in microclimate and soil moisture fluctuation. Site and site by time effects were analyzed using linear mixed models to compare mean differences of microclimate measurements (temperature, relative humidity, and solar radiation) by site as well as by time of the day. Although there were not large differences in seasonal means for these factors, site by time effects show that temperature, humidity, and solar radiation fluctuations increase significantly as shade cover decreases. Soil data showed significantly larger fluctuations in soil moisture gain and loss in the low shade site respective of patterns of precipitation. Overall, the amount of shade cover was directly related to the mitigation of variability in microclimate and soil moisture for the crop of interest. The use of agroforestry systems is an economically feasible way to protect crop plants from extremes in microclimate and soil moisture and should be considered a potential adaptive strategy for farmers in areas that will suffer from extremes in climate.

Bioaccessible selenium in Italian agricultural soils: Comparison of the biogeochemical approach with a regression model based on geochemical and pedoclimatic variables

Biogeochemical mapping of selenium in Italian agricultural soils was accomplished by measuring the Se concentration of representative samples of wheat grains from 71 provinces. The range of the concentration values averaged on a provincial basis was 7-245 ng Se g(-1). A multiple regression model based on six geochemical and pedoclimatic variables was developed to interpret the observed data and to predict Se concentration of wheat in areas where analytical data were missing and in the different Italian soil regions. The statistical model explained only part of the observed variance, but succeeded in identifying Se-enriched as well as Se-depleted areas with an acceptable level of agreement with the biogeochemical map based on measured Se in wheat. Furthermore, the model showed that within the range of concentrations measured in Italian soils, Se-bioaccessibility is controlled not only by the Se content of the soil parent rocks, but also by their overall geochemical nature (carbonatic vs. silicatic) and by pedoclimatic variables (temperature and rain intensity excursions) related to fluctuations of soil moisture and pH. Overall, several Se-marginal and Se-deficient areas were identified on the Italian territory. The implications of these findings for public health are discussed briefly.

Basin‐scale soil moisture dynamics and the probabilistic characterization of carrier hydrologic flows: Slow, leaching‐prone components of the hydrologic response

This paper aims at a first theoretical step toward the probabilistic modeling of nutrient contents in catchment‐scale soil states. To this end, we wish to characterize probabilistically the slow, leaching‐prone component of the hydrologic response, which chiefly determines the export of dissolved nutrients from soil, as a result of interactions between mobile/immobile phases along the pathways of runoff formation. The influence of temporal fluctuations of soil moisture on slow components of the catchment‐scale runoff is thus investigated by means of a stochastic framework, where the intermittency of rainfall is modeled by a marked Poisson process with exponentially distributed intensities. The probability distribution of the relevant runoff components and its moment‐generating function are derived by coupling a stochastic description of soil moisture dynamics with a suitably simplified flow model. New exact solutions are achieved in two different cases, namely, when (1) infiltration rates are assumed proportional to the incoming rainfall depths, i.e., when surface runoff is negligible, and (2) infiltration rates are upwardly bounded by episodical soil saturations (e.g., for shallow soils). In both cases, the derived probability density functions of slow components of runoff are well described by a Gamma distribution, whose shape is controlled by the ratio between the runoff frequency and the inverse of the mean residence time of subsurface flow. The framework developed allows one to link the probabilistic structure of slow components of runoff with simple (pluviometric, soil, vegetation, and geomorphologic) macroscopic parameters, with implications for the ecohydrology of fluvial systems and for drought prediction in ungauged basins. Comparisons with Monte Carlo simulations of a more detailed rainfall‐runoff model to a real catchment located in northeastern Italy suggest the ability of the approach proposed to capture the main features of runoff probability distributions in heterogeneous catchments.

Comparing in situ methods for measuring nitrogen mineralization under mock precipitation regimes

Measurement of soil nitrogen mineralization rates is frequently conducted in situ using a variety of methods, and often producing inconsistent estimates. We conducted a pot experiment to compare rates generated from three different in situ methods (buried bag, covered core, and resin core) under three mock precipitation regimes. Resin core incubations generated the most variable nitrogen mineralization values (9.33–0.09 µg g-1 28 d-1) presumably due to fluctuating soil moisture conditions inherent in the design. Key words: Nitrogen mineralization, in situ incubations, precipitation

Resin Adsorption of Carbon and Nitrogen as Influenced by Season and Time Since Fire

Natural disturbance, such as fire, represents a long‐term displacement of ecosystem dynamics, while seasonal changes, such as spring thaw and summer drought, represent a short‐term perturbation superimposed on the longer disturbance cycle. In spite of the importance in determining forest ecosystem function of these two forms of perturbation, no previous studies have simultaneously investigated the effects of season and fire exclusion on soil C and N dynamics in the inland Northwest. Fire exclusion has resulted in decreased N mineralization due to changes in stand structure and decreased litter quality. However, C and N dynamics are also affected by seasonal fluctuations in soil temperature and moisture. We used ionic and non‐ionic resin capsules to quantify indices of labile C and N including ninhydrin reactive N (NR‐N–amino N), ammonium (NH4+), nitrate (NO3−), anthrone reactive C (AR‐C–hexose sugars), and phenols (low molecular weight aromatics). Repeated measures ANOVA showed that most soil biochemical properties varied significantly with time, season, and their interaction. However, only a few of the variables displayed linear trends with increasing time since fire (TSF), including NR‐N, NH4+–N, and NO3−–N for winter and spring measurements, and AR‐C for the spring measurement, all of which exhibited decreasing levels. Scatter plots showed that NR‐N and AR‐C were sequentially higher with each season, but decreased with TSF and that inorganic N was sequentially lower for each season and also decreased by TSF, except for spring NO3− levels on recently burned sites. None of the variables exhibited a significant difference during the summer measurement, likely as a result of seasonal drought, which emphasizes the importance of sampling time.

Earthworm burrowing in laboratory microcosms as influenced by soil temperature and moisture

Earthworm burrows contribute to soil macroporosity and support diverse microbial communities. It is not well known how fluctuations in soil temperature and moisture affect the burrowing activities of earthworms. The objective of this experiment was to evaluate the maximum depth and length of burrows created by the endogeic earthworm Aporrectodea caliginosa (Savigny) and the anecic earthworm Lumbricus terrestris L. for a range of temperatures (5–20 °C) and soil water potentials (−5 and −11 kPa). The laboratory microcosm was a plexiglass chamber (45 cm high, 45 cm wide) containing 0.14 m 2 of pre-moistened soil and litter, designed to house a single earthworm for 7 days. Earthworm mass, surface casting and burrowing activities were affected significantly by soil temperature, moisture and the temperature×moisture interaction. Burrow length and maximum burrow depth increased with increasing temperature, but there was less burrowing in wetter soil (−5 kPa) than drier soil (−11 kPa). Weight gain and surface casting, however, were greater in soil at −5 kPa than −11 kPa. Our results suggest more intensive feeding and limited burrowing in wetter soil than drier soil. Earthworms inhabiting the non-compacted, drier soil may have pushed aside particles without ingesting them to create burrows. The result was that earthworms explored a larger volume of soil, deeper in the chamber, when the soil was drier. How these burrowing activities may affect the community structure and activity of soil microorganisms and microfauna in the drilosphere remains to be determined.

Growth rates of Aporrectodea caliginosa (Oligochaetae: Lumbricidae) as influenced by soil temperature and moisture in disturbed and undisturbed soil columns

Summary Earthworm growth is affected by fluctuations in soil temperature and moisture and hence, may be used as an indicator of earthworm activity under field conditions. There is no standard methodology for measuring earthworm growth and results obtained in the laboratory with a variety of food sources, soil quantities and container shapes cannot easily be compared or used to estimate earthworm growth in the field. The objective of this experiment was to determine growth rates of the endogeic earthworm Aporrectodea caliginosa (Savigny) over a range of temperatures (5–20 °C) and soil water potentials (−5 to−54 kPa) in disturbed and undisturbed soil columns in the laboratory. We used PVC cores (6 cm diameter, 15 cm height) containing undisturbed and disturbed soil, and 1 l cylindrical pots (11 cm diameter, 14 cm height) with disturbed soil. All containers contained about 500 g of moist soil. The growth rates of juvenile A. caliginosa were determined after 14–28 days. The instantaneous growth rate (IGR) was affected significantly by soil moisture, temperature, and the temperature×moisture interaction, ranging from −0.092 to 0.037 d −1 . Optimum growth conditions for A. caliginosa were at 20 °C and −5 kPa water potential, and they lost weight when the soil water potential was −54 kPa for all temperatures and also when the temperature was 5 °C for all water potentials. Growth rates were significantly greater in pots than in cores, but the growth rates of earthworms in cores with undisturbed or disturbed soil did not differ significantly. The feeding and burrowing habits of earthworms should be considered when choosing the container for growth experiments in order to improve our ability to extrapolate earthworm growth rates from the laboratory to the field.

Flutuações de temperatura e umidade do solo em resposta à cobertura vegetal

Com o objetivo de verificar as flutuações de temperatura e umidade do solo em resposta à cobertura vegetal, realizou-se um experimento com sete diferentes situações de cobertura do solo, constituídas por solo sem cobertura, presença de vegetação espontânea, cultivo de mucuna e plantio de milho a 0, 30, 60 e 90º em relação ao eixo leste-oeste. Dois meses após a semeadura, em janeiro de 1999, por igual período determinou-se o sombreamento nas entrelinhas do milho, às 8:30, 12:30 e 16:30 h, como também, para todos os tratamentos, a temperatura e umidade do solo nas profundidades de 2,5, 5,0 e 7,5 cm; constatou-se diferença no sombreamento entre o cultivo de milho a 0º e os outros ângulos testados nas determinações matutina e vespertina, mas tais diferenças não foram acompanhadas pela temperatura do solo que, neste caso, registrou valores intermediários entre o solo sem cobertura e os tratamentos com vegetação espontânea e mucuna. No tratamento sem cobertura verificou-se a maior amplitude de variação da temperatura ambiente acima da superfície do solo, registrando-se os menores valores de umidade e os maiores de temperatura do solo.

Global warming affect Collembola community: A long-term study

Summary Long-term (1992–2002) effects of climate changes on soil Collembola in Scots pine Pinus sylvestris forests in North Vidzeme Biosphere Reserve (northern Latvia) are investigated. The study was carried out in three forest stands of different age, young (30–40 years), middle aged (50–70 years), and old (150–200 years). One hundred soil samples were collected within each sampling site once a year in autumn over a period of 11 years. In total, 66 species of Collembola were found. Species richness varied between 47 and 56 and density of Collembola from 7300 to 8300 ind m−2. A statistically significant increase in the sums of positive air temperatures (⩾4 °C) was recorded during the period of investigation. Precipitation and thereby soil moisture showed considerable year-to-year fluctuations. Non-metric Multidimensional Scaling of the data yielded two axes explaining 48.6% and 38.6% of the variation. Axis 1 coincided with the trend of sums of positive air temperature ( r = 0.66 ). Axis 1 corresponded best with the negative impact of warming of climate on Collembola, mainly on the euedaphic species inhabiting the deeper layers of the organic soil horizon. Axis 2 was considered reflecting the effect of soil moisture fluctuations (correlation with moisture r = - 0.62 ) on litter dwelling, mostly hemiedaphic Collembola. Species richness tended to decrease gradually in all forest sites during the study period from 29–36 to 13–26 species. Correlation between axes ( r = 0.455 ) indicated interaction effects between positive air temperatures and soil moisture. Forest age showed no substantial effect on the community structure, therefore the changes observed cannot be explained by ecological succession.

Spatial distribution of soil structure in a suburban forest catchment and its effect on spatio-temporal soil moisture and runoff fluctuations

Intensive hydrological observations and model calculations reveal that heterogeneous distributions of soil thickness and soil physical characteristics greatly influence long-term spatio-temporal fluctuations of soil moisture and runoff in a suburban forest, which has rich (thickly wooded) forest but undeveloped forest soil. This paper presents a simple, physical-contour-based model that can describe topography and spatially heterogeneous distributions, and uses the model to clarify how spatial heterogeneous variability influences long-term rainfall runoff processes. The 1.5-ha study catchment features deciduous-evergreen secondary forest and is located near an urban area about 30 km southeast of Nagoya City, in central Japan. This model can simulate saturated/unsaturated throughflow, excess flow, and soil moisture, and has not been calibrated. No input parameters have been fitted and all input parameters are based on published and measured data. Rainfall runoff processes are affected by structural distributions of colluvial/residual soil and spatial heterogeneous distributions of soil thickness. The heterogeneous soil thickness distribution contributes, in particular, to headwater conservation, which moderates storm flow and inhibits drought water flow. The magnitude of headwater conservation and the alignment of individual hillslope elements help to control runoff. The mechanism is attributable to the greater degree of headwater conservation in a suburban forest compared with a homogeneous natural forest. The model also clarifies and predicts water circulation on a larger scale than has been possible to date.

Episodic rewetting enhances carbon and nitrogen release from chaparral soils

The short-term pulse of carbon (C) and nitrogen (N) mineralization that accompanies the wetting of dry soils may dominate annual C and N production in many arid and semi-arid environments characterized by seasonal transitions. We used a laboratory incubation to evaluate the impact of short-term fluctuations in soil moisture on long-term carbon and nitrogen dynamics, and the degree to which rewetting enhances C and N release. Following repeated drying and rewetting of chaparral soils, cumulative CO 2 release in rewet soils was 2.2–3.7 times greater than from soils maintained at equivalent mean soil moisture and represented 12–18% of the total soil C pool. Rewetting frequency did not affect cumulative CO 2 release but did enhance N turnover, and net N mineralization and nitrification increased with rewetting in spite of significant reductions in nitrification potential. Litter addition decreased inorganic N release but enhanced dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) from dry soils, indicating the potential importance of a litter-derived pulse to short-term nutrient dynamics.

Morphology, biomass and nutrient status of fine roots of Scots pine (Pinus sylvestris) as influenced by seasonal fluctuations in soil moisture and soil solution chemistry

A field monitoring study was carried out to follow the changes of fine root morphology, biomass and nutrient status in relation to seasonal changes in soil solution chemistry and moisture regime in a mature Scots pine stand on acid soil. Seasonal and yearly fluctuations in soil moisture and soil solution chemistry have been observed. Changes in soil moisture accounted for some of the changes in the soil solution chemistry. The results showed that when natural acidification in the soil occurs with low pH (3.5–4.2) and high aluminium concentration in the soil solution (>3–10 mg l−1), fine root longevity and distribution could be affected. However, fine root growth of Scots pine may not be negatively influenced by adverse soil chemical conditions if soil moisture is not a limiting factor for root growth. In contrast, dry soil conditions increase Scots pine susceptibility to soil acidification and this could significantly reduce fine root growth and increase root mortality. It is therefore important to study seasonal fluctuations of the environmental variables when investigating and modelling cause-effect relationships.

Evapotranspiration of Two Vegetation Covers in a Shallow Water Table Environment

A method is introduced to estimate evapotranspiration (ET) in shallow water table environments. The method involves measuring the diurnal fluctuations in total soil moisture above the water table to estimate (i) the net lateral and vertical subsurface flux in the aquifer and (ii) evapotranspiration from the vegetation cover. In a hillslope discharge zone, the net lateral subsurface flux was calculated from the recovery rate of soil moisture between midnight and 0400 h. Evapotranspiration was then estimated from a daily water balance in a soil column that included the water table. The method was tested on two vegetation covers, a pasture in a groundwater recharge area, and a riparian zone with woody vegetation in a groundwater discharge area. A moisture probe carrying eight sensors was used in each area to estimate the total soil moisture in a sandy soil environment. The observed water table fluctuated between land surface and a depth of 1.2 m during the study period, allowing observation and estimation of the total soil moisture in a soil column that included the water table. The results of this investigation support another hypothesis that, in humid, shallow water table environments, ET demand may be supported by adjacent ecosystems. This method provided reasonable results for the two landscapes investigated and was able to capture the variability of evapotranspiration in heterogeneous vegetation covers. It provided a relatively inexpensive alternative to characterize ET within regionally heterogeneous but microhomogenous landscapes. Though tested for coarse‐textured soil, the method involving soil moisture monitoring can be easily adapted to other soil types with shallow water table. Another advantage of using this method is that ET can be successfully estimated without detailed knowledge of soil hydraulic properties, subsurface flow patterns, or vegetation characteristics.

The Effect of Soil and Vegetation Parameters in the ECMWF Land Surface Scheme

Abstract Numerical Weather Prediction (NWP) and climate models are sensitive to evapotranspiration at the land surface. This sensitivity requires the prediction of realistic surface moisture and heat fluxes by land surface models that provide the lower boundary condition for the atmospheric models. This paper compares simulations of a stand-alone version of the European Centre for Medium-Range Weather Forecasts (ECMWF) land surface scheme, or the Viterbo and Beljaars scheme (VB95), with various soil and vegetation parameter sets against soil moisture observations across the Murrumbidgee River catchment in southeast Australia. The study is, in part, motivated by the adoption of VB95 as the operational land surface scheme by the Australian Bureau of Meteorology in 1999. VB95 can model the temporal fluctuations in soil moisture, and therefore the moisture fluxes, fairly realistically. The monthly model latent heat flux is also fairly insensitive to soil or vegetation parameters. The VB95 soil moisture is sensitive to the soil and, to a lesser degree, the vegetation parameters. The model exhibits a significant (generally wet) bias in the absolute soil moisture that varies spatially. The use of the best Australia-wide available soils and vegetation information did not improve VB95 simulations consistently, compared with the original model parameters. Comparisons of model and observed soil moistures revealed that more realistic soil parameters are needed to reduce the model soil moisture bias. Given currently available continent-wide soils parameters, any initialization of soil moisture with observed values would likely result in significant flux errors. The soil moisture bias could be largely eliminated by using soil parameters that were derived directly from the actual soil moisture observations. Such parameters, however, are only available at very few point locations.

The Palmer Drought Severity Index (PDSI) as an indicator of soil moisture

Detailed observation of soil moisture time series has of practical importance either in strategic preparing of researches or in professional planning. Meteorological-related spatial and temporal connections of soil moisture were investigated on monthly Palmer Drought Severity Index (PDSI) time series of five meteorological stations in Eastern Hungary (Miskolc, Nyı́regyháza, Debrecen, Kecskemét and Szeged) for the period 1901–1999. The calculated PDSI values were compared with the soil moisture content of the upper one meter soil layer. The measured soil moisture time series come from the authors ([Dunkel, Z., 1994; Lambert, K., et al., 1993 (in Hungarian)]). Both the used soil moisture time series and the Pálfai-index, expressing numerically daily hydrological extremes ([Pálfai, I.,1991]), confirmed our result independently of each other according to which PDSI is a good indicator of the soil moisture fluctuations in the upper one meter soil layer of the Great Hungarian Plain. On the basis of the regression coefficients of the linear connection, the index values can be expressed in physical unit of the water content in the upper one meter soil layer, as well. As a result of our examinations, the index has favourable statistical features; namely, the distribution of monthly samples is normal. Analysing spatial and temporal connections of the varied hydrometeorological relations of the selected region, average spatial and strong temporal correlations were established and these results are functions of intra-annual variability of precipitation.

Influence of Tillage and Mulching Systems on Soil Water and Tomato Fruit Yield and Quality

ABSTRACT Many growers have interests in using mulches, cover crops, and conservation tillage systems in tomato production, but also have concerns about the effect of soil moisture fluctuations on fruit quality. Percent soil moisture and ‘Fabulous’ tomato (Lycopersicon esculentum Mill.) fruit production in response to different mulching/tillage systems within wheat (Triticum aestivum L.) and winter rye (Secale cereale L.) cover crops were evaluated. Treatments applied following the mowing of the cover crops were: (1) conventional tillage (CT); (2) black polyethylene plastic over conventional tillage (BP); (3) no-tillage with cover crop killed with 1.5% glyphosate one week prior to transplanting (NT); (4) strip-tillage with cover crop killed with a 1.5% glyphosate one week prior to transplanting (ST); (5) no-tillage in which the cover crop was mowed periodically during the growing season [NT-Lm (living mulch)]; and (6) strip-tillage with the cover crop mowed and treated similar to treatment 5 (ST-Lm). Generally, there were no differences (P < 0.05) between winter rye and wheat cover crops with respect to tomato quality or yields. Large amounts of cull fruit were produced in both years, regardless of moisture; however, blossom-end rot was more severe across treatments during 1999. Under drought conditions (1999 growing season), all conservation tillage treatments had higher soil moisture readings 24 hrs after rainfall than other treatments, but BP had higher moisture levels than all other treatments under times of excessive water depletion. Under a condition of sufficient soil moisture (2000 growing season), black plastic resulted in higher soil moisture early in the season than CT or conservation tillage systems, a response associated with greater total marketable yields. Comparisons between the various conservation tillage treatments for soil moisture and tomato yields were inconclusive, but with adequate and consistent soil moisture, conservation and conventional tillage treatments produced similar marketable yields.

Soil Organic Matter Content Effects on Apple Root Dynamics

Soil organic matter is a critical component which is fundamental in plant growth. Several soil factors are influenced by organic matter such as slow release of nutrients, increased water holding capacity, improved soil physical characteristics and improved environment for soil microorganisms. The aim of this work is to investigate the physical effect of organic matter content in the soil on apple root growth and development. Twenty five two-year old apple trees (Malus domestica, Borkh) cv. `Buckeye Gala' on M.9 NAKB 337 rootstock were planted in completely transparent acrylic boxes. Plants have been grown in a green house to avoid external rain in a complete randomized design. Trees were planted in a sandy-mix soil amended with soil high in organic matter, “muck”, at four incremental levels. Treatments compared were a control (sandy soil with 0% organic matter) and 1%, 2%, 4% and 8% soil organic matter. The amount of water applied by automatic drip irrigation was comparable for all the treatments to avoid high fluctuation of soil moisture on root dynamics. All treatments have been fertilized with the same amount of mineral fertilizer to avoid the nutrition effect on root dynamics. Digital photos of roots were taken to study their dynamics every one to two weeks during a period of five months. Roots have been highlighted with Photoshop and then analyzed with WinRhizo to measure root length, area, lifespan and dynamics. At the end of the growing period plants have been harvested and fresh and dry weight was evaluated to asses the root/shoot ratio. The effects of the treatments on root length, area, lifespan and dynamics, and root/shoot ratio will be discussed.

Long-term fluctuation of the soil fauna (Collembola and Oribatida) at groundwater-near sites in an alder wood

Collembola and oribatid mites were investigated at four sites along a cross section in an alder wood at a lake margin (northern Germany) over a period of 7 years. Monthly samples of the litter and the mineral layer were taken. Additionally, fluctuations of groundwater level, soil moisture, precipitation and soil temperature at 2 cm depth were measured. The alder wood was characterised by a depression between the lake margin and the foot of a hill slope, where waterlogged periods occurred. Groundwater level was the main environmental factor influencing the composition of collembolan and oribatid mite assemblages. Climatic factors, e.g. July temperature and July precipitation were also found to be significant factors, but with a much lower influence. Collembola predominantly showed higher variation in time than in space indicating that more collembolan species migrate within the investigated cross section or react with higher abundance fluctuations on the groundwater level changes, while Oribatida had a higher part of space variation, indicating that migration potential is lower and the environmental gradient is of higher influence on the distribution. Reaction time of soil fauna species on the groundwater fluctuation varies between 1 and 12 months. Retreat of Collembola from the waterlogged situation was between 4 and 6 months in the litter layer and 3 months in the mineral layer. Recolonisation of the waterlogged site lasted approximately 12 months. A positive reaction by precipitation was observed in four collembolan species that was 1 month in the edaphic species and between 9–10 months in the larger litter dwelling species. Only few oribatid mites reacted on the waterlogged situation.

Short-term impact of forest soil compaction and organic matter removal on soil mesofauna density and oribatid mite diversity

This study examines the short-term impact of forest soil compaction and organic matter removal on soil mesofauna, in general, and oribatid mite species, in particular. Both soil compaction and organic matter removal reduced the density of soil mesofauna. Stem-only harvesting reduced total mesofauna densities by 20% relative to uncut forest values. A combination of whole-tree harvest and forest floor removal with heavy soil compaction significantly reduced total soil mesofauna densities by 93% relative to the uncut forest control. Removal of the forest floor represents a substantial loss of habitat for most soil mesofauna. The forest floor apparently buffered the mineral soil by limiting both the impact of soil compaction and fluctuations in soil temperature and moisture. The relative abundance of Prostigmata and Mesostigmata increased with treatment severity, whereas that of Oribatida decreased. Species richness of the oribatid mite fauna was reduced as the severity of treatments increased. The number of rare oribatid species (those representing &lt;1% of the total oribatid mite sample) decreased by 40% or more relative to the uncut forest control. Evenness also decreased as treatment severity increased. Oppiella nova and Suctobelbella sp. near acutidens were the dominant oribatid species in both the forest floor and mineral soil, regardless of treatment. Soil compaction and organic matter removal significantly impacted the density and diversity of soil mesofauna and oribatid mite fauna in the short term at these study sites.