Undisturbed Forest Soils Research Articles

Interactive influences of climate and parent material on soil microbial community structure in Bornean tropical forest ecosystems

AbstractClimate and parent material strongly control vegetation structure and function, yet their control over the belowground microbial community is poorly understood. We assessed variation in microbial lipid profiles in undisturbed forest soils (organic and surface mineral horizons) along an altitudinal gradient (700, 1,700, and 2,700 m a.s.l. mean annual temperature of 12–24°C) on two contrasting parent materials (acidic metasedimentary vs. ultrabasic igneous rock) in Mt. Kinabalu, Borneo. Soil organic carbon and nitrogen concentrations were generally higher at higher altitudes and, within a site, at upper soil horizons. Soil pH ranged from 3.9 to 5.3, with higher values for the ultrabasic soils especially at higher altitudes. The major shifts in microbial community structure observed were the decline in the ratio of fungal to bacterial lipid markers both with increasing soil depth and decreasing altitude. The positive correlation between this ratio with soil C and N concentrations suggested a strong substrate control in accord with the literature from mid to high‐latitude ecosystems. Principal component analysis using seven groups of signature lipids suggested a significant altitude by parent material interaction—the significant difference in microbial community structure between the two rock types found at 2,700‐m sites developed on weakly weathered soils diminished with decreasing altitude towards 700‐m sites where soils were strongly weathered. These results are consistent with the hypothesis that parent material effect on soil microbial community (either directly via soil geochemistry or indirectly via floristic composition) is stronger at an earlier stage of ecosystem development.

In Situ Generated Colloid Transport of Cu and Zn in Reclaimed Mine Soil Profiles Associated with Biosolids Application

Areas reclaimed for agricultural uses following coal mining often receive biosolids applications to increase organic matter and fertility. Transport of heavy metals within these soils may be enhanced by the additional presence of biosolids colloids. Intact monoliths from reclaimed and undisturbed soils in Virginia and Kentucky were leached to observe Cu and Zn mobility with and without biosolids application. Transport of Cu and Zn was observed in both solution and colloid associated phases in reclaimed and undisturbed forest soils, where the presence of unweathered spoil material and biosolids amendments contributed to higher metal release in solution fractions. Up to 81% of mobile Cu was associated with the colloid fraction, particularly when gibbsite was present, while only up to 18% of mobile Zn was associated with the colloid fraction. The colloid bound Cu was exchangeable by ammonium acetate, suggesting that it will release into groundwater resources.

An experimental investigation to characterise soil macroporosity under different land use and land covers of northeast India

Saturated macropore flow is the dominant hydrological process in tropical and subtropical hilly watersheds of northeast India. The process of infiltration into saturated macroporous soils is primarily controlled by size, network, density, connectivity, saturation of surrounding soil matrix, and depthwise distribution of macropores. To understand the effects of local land use, land cover and management practices on soil macroporosity, colour dye infiltration experiments were conducted with ten soil columns (25 × 25 × 50 cm) collected from different watersheds of the region under similar soil and agro-climatic zones. The sampling sites included two undisturbed forested hillslopes, two conventionally cultivated paddy fields, two forest lands abandoned after Jhum cultivation, and two paddy fields, one pineapple plot and one banana plot presently under active cultivation stage of the Jhum cycle. Digital image analyses of the obtained dye patterns showed that the infiltration patterns differed significantly for different sites with varying land use, land cover, and cultivation practices. Undisturbed forest soils showed high degree of soil macroporosity throughout the soil profile, paddy fields revealed sealing of macropores at the topsoil due to hard pan formation, and Jhum cultivated plots showed disconnected subsoil macropores. The important parameters related to soil macropores such as maximum and average size of macropores, number of active macropores, and depthwise distribution of macropores were estimated to characterise the soil macroporosity for the sites. These experimentally derived quantitative data of soil macroporosity can have wide range of applications in the region such as water quality monitoring and groundwater pollution assessment due to preferential leaching of solutes and pesticides, study of soil structural properties and infiltration behaviour of soils, investigation of flash floods in rivers, and hydrological modelling of the watersheds.

Tracing solute infiltration using a combined method of dye tracer test and electrical resistivity tomography in an undisturbed forest soil profile

An accurate prediction of solute infiltration in a soil profile is important in the area of environmental science, groundwater and civil engineering. We examined the infiltration pattern and monitored the infiltration process using a combined method of dye tracer test and electrical resistivity tomography (ERT) in an undisturbed field soil (1 m × 1 m). A homogeneous matrix flow was observed in the surface soil (A horizon), but a preferential flow along macropores and residual rock structure was the dominant infiltration pattern in the subsurface soil. Saturated interflow along the slopping boundaries of A and C1 horizons and of an upper sandy layer and a lower thin clay layer in the C horizon was also observed. The result of ERT showed that matrix flow started first in A horizon and then the infiltration was followed by the preferential flows along the sloping interfaces and macropores. The ERT did not show as much detail as the dye-stained image for the preferential flow. However, the area with the higher staining density where preferential flow was dominant showed a relatively lower electrical resistivity. The result of this study indicates that ERT can be applied for the monitoring of solute transportation in the vadose zone. Copyright © 2010 John Wiley & Sons, Ltd.

Species and genera of soil nematodes in forest ecosystems of the Vihorlat Protected Landscape Area, Slovakia

Abstract Fauna of soil nematodes was studied in three main forest types of the Vihorlat Mountains, Querceto-Fageto-Aceretum at Remetské Hámre (RH), Fagetum at Morské oko (MO), and Fageto-Aceretum at Sninský kameň (SK). Each forest type was represented by five sites. In total 198 species and 98 genera of soil nematodes were distinguished. Most species belonged to rare taxa with the frequency of occurrence lower than 50 %. The number of species and genera decreased from RH (167 species and 86 genera) through MO (115 and 68) to SK (87 and 51). Species and generic richness was significantly positively correlated with soil pH(H2O), negatively with altitude, soil moisture and Cox. Greater part of nematode species and genera belonged to microbivores and to the taxa with higher cp values of 3 – 5. We can conclude that rich nematode fauna indicated undisturbed forest soil condition, nevertheless, the richness decreased with increasing altitude.

Genetic Heterogeneity in Wild Isolates of Cellular Slime Mold Social Groups

This study addresses the issues of spatial distribution, dispersal, and genetic heterogeneity in social groups of the cellular slime molds (CSMs). The CSMs are soil amoebae with an unusual life cycle that consists of alternating solitary and social phases. Because the social phase involves division of labor with what appears to be an extreme form of "altruism", the CSMs raise interesting evolutionary questions regarding the origin and maintenance of sociality. Knowledge of the genetic structure of social groups in the wild is necessary for answering these questions. We confirm that CSMs are widespread in undisturbed forest soil from South India. They are dispersed over long distances via the dung of a variety of large mammals. Consistent with this mode of dispersal, most social groups in the two species examined for detailed study, Dictyostelium giganteum and Dictyostelium purpureum, are multi-clonal.

Nitrogen availability from peat amendments used in boreal oil sands reclamation

Following surface mining, peat is typically used as an organic amendment to cap reconstructed soils in the Athabasca oil sands region of Alberta. Yet, very little is known about its ability to provide available nitrogen (N) in these soils. Hence, the overall objective of this study was to measure soil nitrogen (N) availability throughout the year in five peat amendments. Specific objectives were: (1) to examine seasonal variability in soil labile N pool sizes (nitrate, ammonium, dissolved organic N, and microbial biomass N), and (2) to determine in situ net nitrification, ammonification, and mineralization rates using the resin-core technique. Results from this field incubation method indicated a strong seasonal variability in net mineralization rates, with maximum positive values in the fall, and low or negative rates in winter. Net ammonification rates, which were significantly correlated to soil moisture content, were significantly smaller and showed smaller seasonal fluctuations and fewer differences among peat materials than net nitrification rates. Furthermore, the contribution of net nitrification to total net mineralization rates was characteristically higher than what is typically observed in undisturbed boreal forest soils. Taken together, results indicate that net nitrification processes may control nitrogen availability in these reclaimed soils.Key words: Soil nitrogen, soil reclamation, nitrification, mineralization, boreal soils

Identification of Sediment Sources in Forested Watersheds With Surface Coal Mining Disturbance Using Carbon and Nitrogen Isotopes1

Abstract: Sediments and soils were analyzed using stable carbon and nitrogen isotope ratio mass spectrometry and carbon and nitrogen elemental analyses to evaluate the their ability to indicate land‐use and land management disturbance and pinpoint loading from sediment transport sources in forested watersheds disturbed by surface coal mining. Samples of transported sediment particulate organic matter were collected from four watersheds in the Southern Appalachian forest region of southeastern Kentucky. The four watersheds had different surface coal mining history that were classified as undisturbed, active mining, and reclaimed conditions. Soil samples were analyzed including reclaimed grassland soils, undisturbed forest soils, geogenic organic matter associated with coal fragments in mining spoil, and soil organic matter from un‐mined grassland soils. Statistically significant differences were found for all biogeochemical signatures when comparing transported sediments from undisturbed watersheds and surface coal mining disturbed watersheds, and the results were attributed to differences in erosion sources and the presence of geogenic organic matter. Sediment transport sources in the surface coal mining watersheds were analyzed using Monte Carlo mass balance un‐mixing and it was found that: δ15N showed the ability to differentiate streambank erosion and surface soil erosion; and δ13C showed the ability to differentiate soil organic matter and geogenic organic matter. Results from the analyses suggest that streambank erosion downstream of surface coal mining sites is an especially significant source of sediment in coal mining disturbed watersheds. Further, the results suggest that the sediment transport processes governing streambank erosion loads are taking longer to reach geomorphologic equilibrium in the watershed as compared with the surface erosion processes. The dual‐isotope technique provides a useful method for further investigation of the impact of surface coal mining in the uplands of the watershed upon the geomorphologic state of the channel and the source of organic matter in aquatic systems impacted by surface coal mining.

Carbon and Nitrogen Isotopic Measurements from Southern Appalachian Soils: Assessing Soil Carbon Sequestration under Climate and Land-Use Variation

Measurements of the distribution of carbon and nitrogen isotopes in soils are needed due to their potential to improve our understanding of soil CO 2 emissions and sequestration under varying climatic conditions and land management technologies. Organic carbon and nitrogen isotopic and elemental composition was measured in baseline forest soils as well as in anthropogenically and intermittently flooded soils in the southern Appalachian Mountains. For the undisturbed forest soils, the consistent relationship between elemental and isotopic composition in the soil column, across soil organic matter pools, was supportive of the hypothesis that isotopic signature is reflective of microbial induced carbon turnover and nitrogen decomposition. A climatologic analysis suggested that isotopic indicators of soil organic matter turnover were influenced by mean annual temperature at our study sites, as well as in 10 other regional and global soil carbon and nitrogen isotopic studies. Intermittently flooded soils showed carbon and nitrogen distributions that reflected successive high magnitude events where sediments were deposited upon a developing forest floor. Measurements from soils disturbed by mining, agriculture, and recreation suggest the potential for using carbon and nitrogen isotopes to indicate the degree of soil organic matter turnover induced by different land management scenarios.

Natural radionuclides and trace elements in rice field soils in relation to fertilizer application: study of a chronic kidney disease area in Sri Lanka

The rising number of chronic kidney disease patients with no identifiable cause (CKD of uncertain aetiology), prevalent in some areas of the dry zone of Sri Lanka is suspected to be related to the environmental exposure to heavy metals. Agricultural soils are well recognized as being contaminated with potentially toxic metals from various forms of fertilizers and agro-chemicals, which could easily enter the human body through the food chain. The objective of this paper is to determine the content of heavy metals and activity concentration of background radionuclides such as K-40, Ra-226 and Th-232, in rice field soils. Rice farming is the most common agricultural practice in the affected region and possible heavy metal sources such as fertilizers are applied in abundance in the rice fields. Soils collected from a rice field in a non-CKD region was used for the comparison. In dry zone soils, Ca, K, Ba, Pb and Zr contents were higher and Fe, Mn, Cr, Ni and Zn contents were lower compared to that of soils from the wet zone non-CKD region. However, the activity concentration of soils was mostly the same in all samples, except for the K-40 contents of the soils, which were higher in the rice field soils compared to the undisturbed forest soils and also to the world averages. The mean U content was 3.6 mg/kg in the studied soils, although extremely high uranium contents were found in some fertilizer samples particularly in the triple superphosphates. Most uranium applied via fertilizer could contaminate the drinking water sources and even low uranium concentrations in drinking water may cause nephrotoxic effects.

Soil carbon pools of reclaimed minesoils under grass and forest landuses

AbstractMinesoils are characterized by low soil organic matter and poor soil physicochemical environment. Mine soil reclamation process has potential to restore soil fertility and sequester carbon (C) over time. Soil organic C (SOC) pool and associated soil properties were determined for reclaimed minesoils under grass and forest landuses of varied establishment year. Three grassland sites of 30, 9, and 1 years after reclamation (G30, G9, and G1) and two forest sites, 11 years after reclamation (RF) and undisturbed stand of 40 years (UF), were selected within four counties (Morgan, Muskingum, Noble, and Coshocton) of southeastern Ohio. Soil bulk density (BD) of reclaimed forest (RF) soil was significantly higher than undisturbed forest (UF) soils within 10–40 cm soil depth profile. Reclamation process increased soil pH from slightly acidic to alkaline and decreased the soil EC in both landuses. Among grassland soils, significant changes in SOC and total soil N contents were observed within 0–10 cm soil depth. SOC contents of G30 (29.7 Mg ha−1) and G9 (29.5 Mg ha−1) were significantly higher than G1 soils (9.11 Mg ha−1). Soil N content was increased from G1 (0.95 Mg ha−1) to G9 (2.00 Mg ha−1) site and then the highest value was found under G30 (3.25 Mg ha−1) site within 0–10 cm soil depth. UF soils had significantly higher SOC and total N content than RF soils at 0–10 and 10–20 cm soil depths. Copyright © 2009 John Wiley & Sons, Ltd.

A soil quality index based on the equilibrium between soil organic matter and biochemical properties of undisturbed coniferous forest soils of the Pacific Northwest

Recent studies have suggested that the organic matter contents of undisturbed soils (under natural vegetation) are in equilibrium with biological and biochemical properties. Accordingly, we hypothesised that such equilibria should be disrupted when soils are subjected to disturbance or stress, and that measurement of this disruption can be expressed mathematically and used as a soil quality index. In this study, we evaluated these hypotheses in soils from the H.J. Andrews Experimental Forest in Oregon. Both O and A horizons were sampled from nine sites in Spring 2005 and Fall 2006. Soil samples were analyzed for enzyme activities (phosphatase, β-glucosidase, laccase, N-acetyl-glucosaminidase, protease and urease), and other biological and chemical properties including N-mineralization, respiration, microbial biomass C (MBC), soil organic carbon (SOC) and total nitrogen content. In addition, soil samples from one old-growth site were manipulated in the laboratory to either simulate chemical stresses (Cu addition or pH alteration) or physical disturbances (wet–dry or freeze–thaw cycles). The results showed variation in biological and biochemical soil properties that were closely correlated with SOC. Multiple regression analysis of SOC levels against all soil properties showed that a model containing only MBC and phosphatase activity could account for 97% of the SOC variation among the sites. The model fit was independent of spatial and temporal variations because covariates such as site, stand age, sampling date, and soil horizon were found to be not statistically significant. Although the application of stress/disturbance treatments inconsistently affected most of the individual biochemical properties, in contrast, the ratio of soil C predicted by the model ( C p), and soil C measured ( C m) was consistently reduced in soils submitted to at least one level of stress and disturbance treatments. In addition, C p/ C m was more affected in soils submitted to wet–dry cycles and Cu contamination than to freeze–thaw cycles or shifts in soil pH. Our results confirm previous evidence of a biochemical balance in high quality undisturbed soils, and that this balance is disrupted when the soil is submitted to disturbances or placed under stress conditions. The C p/ C m ratio provides a simple reference value against which the degrading effects of pollutants or management practices on soil quality can be assessed.

Charcoal production at kiln sites affects C and N dynamics and associated soil microorganisms in Quercus spp. temperate forests of central Mexico

Temperate forests dominated by Quercus spp. cover large parts of Central Mexico and rural communities depend on these forests for wood and charcoal. The impacts of charcoal production on selected chemical properties including C and N dynamics, and populations of ammonifiers, nitrifiers and denitrifiers were investigated on surface soils (0–15 cm) collected during the dry and rainy season of these forests. Organic C was halved in soil at the kiln sites compared to undisturbed forest soil. Concentrations of exchangeable Ca 2+, K + and Mg 2+ increased >1.6 times at kiln sites and pH increased from 4.5 in undisturbed soil to 7.0 at kiln sites. The kiln sites had 1.3 times and 2.4 times lower microbial biomass C and N, respectively, than undisturbed forest sites during the rainy season. Although the effect of charcoal production on NH 4 +, NO 2 − and NO 3 − concentrations was small, the ammonifying, nitrifying and denitrifiers were 16 times lower at the kiln sites than in the undisturbed forest soil. This research found that the charcoal production had a negative effect on the cultivable microorganisms involved in N cycling and the soil microbial biomass C and N compared to undisturbed forest soil. Differences in inorganic N dynamics were more affected by seasonality, i.e. precipitation, than by charcoal production.

Three New Species of Aspergillus from Amazonian Forest Soil (Ecuador)

From an undisturbed natural forest soil in Ecuador, three fungal strains of the genus Aspergillus were isolated. Based on molecular and morphological features they are described as three new species, named A. quitensis, A. amazonicus, and A. ecuadorensis.

Distribution and Migration of Heavy Metals in Undisturbed Forest Soils: A High Resolution Sampling Method

The vertical distribution and migration of Cu, Zn, Pb, and Cd in two forest soil proflles near an industrial emission source were investigated using a high resolution sampling method together with reference element Ti. One-meter soil proflle was sectioned horizontally at 2 cm intervals in the flrst 40 cm, 5 cm intervals in the next 40 cm, and 10 cm intervals in the last 20 cm. The migration distance and rate of heavy metals in the soil proflles were calculated according to their relative concentrations in the proflles, as calibrated by the reference element Ti. The enrichment of heavy metals appeared in the uppermost layer of the forest soil, and the soil heavy metal concentrations decreased down the proflle until reaching their background values. The calculated average migration rates of Cd, Cu, Pb, and Zn were 0.70, 0.33, 0.37, and 0.76 cm year −1, respectively, which were comparable to other methods. A simulation model was proposed, which could well describe the distribution of Cu, Zn, Pb, and Cd in natural forest soils.

Validating the effectiveness and sensitivity of two soil quality indices based on natural forest soils under Mediterranean conditions

Soils from natural ecosystems have specific physical, chemical and biochemical properties determined by the conditions in which these soils have developed. These soils that develop without external disturbance reach a balance amongst their properties. Thus, the creation of a model that represents the established balance of different soil properties from stable ecosystems can be used as a soil quality index, thus any perturbation must lead to modifications in this natural balance. Two regression models with soils from undisturbed forest regions in eastern Spain were previously developed, representing the balance between organic carbon and some physical, chemical and biochemical properties. For undisturbed forest soils, the prediction of soil organic carbon (SOCc) with the calibrated models should be similar to the actual value of this variable (SOCa) (SOCc ≈ SOCa). Consequently, the residuals (SOCc − SOCa) should be around 0. On the contrary, disturbance practices cause a disruption in the balance defined between the different properties and SOC. As a consequence, residuals must be < or >0. Furthermore, the more the degree of degradation increases, the more the values of SOCc must differ from the values of SOCa. According to this, two soil quality indices (SQI) were defined, one for each model, by the calculation of the model residuals (SQI = SOCc − SOCa). The SQIs have been applied to different undisturbed forest soils to evaluate their validity. In addition, they have also been applied to severely altered soils, like agricultural soils, and abandoned agricultural fields, to assess the sensibility of this index to perturbations. After applying the soil quality indices to eleven undisturbed forest soils, it has been verified that a balance exists between organic matter content and different physical, chemical and biochemical properties in forest soils from SE Spain, and the proposed calibrated models are capable of reflecting that balance (SQI ≈ 0). Our results confirm that our models are sensitive to soil perturbation, because agricultural and abandoned agricultural soils have shown an imbalance between organic carbon content and the physical, chemical and biochemical properties (SQI > 0). Moreover, soils from abandoned fields showed lower deviation in the natural equilibrium, indicating a recovery of soil quality.

Tree species-specific effects on soil microbial residues in an upper Michigan old-growth forest system

Summary Microbial contribution to carbon and nitrogen cycling in forest soils is important, and may depend on tree species. The amount of amino sugars and their ratios can serve as reliable indicators for bacterial and fungal contribution. We compare forest fl oor microbial residues (amino sugars) beneath three canopy-tree species (Sugar Maple (SM), Acer saccharum Marsh; Basswood (BA), Tilia americana L.; Eastern Hemlock, Tsuga canadensis L.) replicated in fi ve plots in an upper Michigan old-growth forest. We hypothesized that because individual tree species develop a unique microbial community over time, they will accumulate microbial residues to different degrees. In this study at three tree species sites, the absolute amount of fungal residue (glucosamine (GluN)) was relatively constant, while absolute quantities of bacterial residues (galactosamine (GalN) and muramic acid (MurA)) were least in the Hemlock site. Amino sugar ratios revealed that microbial residues were compositionally distinct in the three sites. The lower ratios of GluN to GalN and GluN to MurA in BA and SM sites relative to Hemlock site indicate the lower net accumulations of GalN and MurA in Hemlock site. In terms of microbial contribution to carbon and nitrogen cycle in forest soils, we suggest that caution may be needed when using amino sugars as a tool, especially for nitrogen pool assessment, as the amino sugars are diluted by plant-derived litter. This study provides information on the microbial residues in undisturbed forest soils which may assist interpretation of data derived from managed or damaged forests in the future.

Relationships among forest soil C isotopic composition, partitioning, and turnover times

The purpose of this research was to test the hypothesis that vertical enrichment of soil δ13C values is related to rates of soil C turnover in undisturbed, mature forest ecosystems. Soil C and N were measured at nine sites along an altitudinal gradient in the southern Appalachian Mountains (Tennessee and North Carolina, USA). Measurements indicated greater labile and total soil C stocks with increasing altitude. Laboratory incubations (3 days) of rewetted, air-dry soils indicated potential soil C mineralization (µg CO2 produced·g–1 soil C) declined with elevation. A principal component analysis indicated N availability increased with altitude. At each site, there was a significant relationship between δ13C and log-transformed C concentrations in the soil profile (30 cm deep). Enrichment factors (ε) from the Rayleigh equation were also equally useful for describing soil δ13C profiles at each site. Soil C partitioning and turnover times along the gradient were correlated with 13C-enrichment factors. Greater rates of change in δ13C through the soil profile were correlated with faster soil C turnover. Environmental factors, soil C partitioning, and the rate of vertical change in soil 13C abundance are interrelated such that δ13C measurements are a potential indicator of C dynamics in undisturbed forest soils.

Changes in pore size distribution and hydraulic properties of forest soil resulting from structural development

To examine how rainwater dynamics on a forested hillslope change as a result of forest biological activities altering the development of pore structure, we analyzed the pore size distributions and hydraulic properties of forest soils under disturbed and undisturbed conditions. Undisturbed soil samples were collected in nine forests on Mt. Rokkou and Sakurajima Island, Japan, and disturbed soil samples were prepared using the same samples. We measured water retention curves, saturated hydraulic conductivities, and particle size distributions. Results showed that while pore size distributions and saturated hydraulic conductivities of disturbed soils were mainly influenced by particle size distributions, undisturbed forest soils had relatively similar pore size distributions and saturated hydraulic conductivities after secondary soil pores were formed as a result of forest biological activities. The undisturbed forest soils contained more large pores and fewer intermediate-size pores than the disturbed soils. We also found that undisturbed forest soils had a higher water content than the disturbed soils. As secondary soil pores developed, the median pore radius and the width of the pore size distribution increased, and the soil water diffusivity tended to decrease. The saturated hydraulic conductivity was proportional to the square of the median pore radius for all samples. Numerical simulations conducted assuming the mean hydraulic properties for disturbed and undisturbed soils revealed that the development of soil structure in forest soils has the effect of decreasing storm runoff and increasing base flow discharge.

Effects of small-scale habitat fragmentation, habitat corridors and mainland dispersal on soil decomposer organisms

Habitat corridors have been suggested to be one possible way to reduce the often negative effects of habitat fragmentation. In the present experiment, we focused on small habitat fragments (humus patches) inhabited by soil decomposer organisms. These fragments were either unconnected or connected with each other by habitat (humus) corridors. Moreover, these systems were either isolated from the mainland by a dispersal barrier (plastic “walls”) or were open to dispersal from the mainland. The fragments and corridors were embedded in a matrix of mineral soil that was expected to be uninhabitable or at least an unpreferred habitat for the organisms studied. Undisturbed forest soil functioned as the mainland. The results showed that habitat fragmentation decreased the abundance of microarthropods (Acari). Presence of corridors affected positively the abundance of mites, but only after the first 4 months of the experiment: later on, this effect disappeared. Furthermore, this “corridor rescue effect” was only seen in the systems isolated from the mainland, whereas in the open systems, dispersal from the mainland apparently overwhelmed the effect of corridors. Also soil fungi benefited from the corridors. The results indicate that soil decomposer organisms, microarthropods in particular, may be useful as model organisms in studies focusing on the ecological consequences of habitat fragmentation. It is also suggested that connecting otherwise isolated small habitat fragments with each other by habitat corridors may increase the persistence time of fragment-inhabiting populations.