Effects of short term bioturbation by common voles on biogeochemical soil variables

Let’s make a mess, maybe no one will notice. The impact of bioturbation activity on the urn fill condition

The research was carried out at the cremation cemetery of the Lusatian culture in Wtórek, Ostrów Wielkopolski district, Wielkopolska province, Poland. Contrary to the so-far-studied topics related to the CT imaging of burnt bones and their virtual exploration, we concentrated on the analysis of the structures formed by the soil fauna activity in the fills of urns and additional vessels, and reconstruction of the dynamics of the ecosystem variability within the cemetery area based on thereof. We also demonstrated the impact of macrofaunal activity on stratigraphy and bone fragmentation. From the total of 222 excavated burials in 18 urns and one additional vessel, the remains of macrofauna or its bioturbation activity were identified. Out of 19 vessels subjected to CT examinations, traces of macrofaunal activity were demonstrated in 13: in five vessels animal bioturbative activity was not observed and in one, observations was impossible (due to significant metal-related artifacts). In two vessels both macrofaunal remains and traces of activity were identified. Discovered bioturbations were associated with specific species or genera. Nests or their parts of the genus Geotrupes sp. beetles were the most frequently observed traces of macrofaunal activity. Tunnels and aestivation chambers of earthworms and chambers of the genus Harpalus sp. beetles filled with Setaria sp. caryopses were discovered. The chitinous parts of other insects and the humerus bones of the vole of the genus Microtus sp. were also identified. It was shown, especially due to the non-destructive method, that rodents activity had the most destructive effect on the bone stratigraphy as well as on the movement and fragmentation of the burnt bones. The chances of visualizing bioturbations decreased with time since their creation. The process of disappearance of traces of macrofaunal activity concerned both traces of rodent activity and nests set up by Geotrupes sp. and other species.

Effect of vole bioturbation on N2O, NO, NH3, CH4 and CO2 fluxes of slurry fertilized and non-fertilized montane grassland soils in Southern Germany

Populations of rodents such as common vole (Microtus arvalis) can develop impressive soil bioturbation activities in grasslands. These burrowing and nesting activities highly impact soil physicochemical properties as well as vegetation coverage and diversity. Managed grasslands in livestock production regions receive significant amounts of slurry, commonly at high loads at the beginning of the vegetation period. However, nothing is known how the combination of vole bioturbation and slurry application may affect the fluxes of C and N trace gases from grasslands. Here we report on an in-situ experiment and supporting laboratory incubations carried out during the period March to May 2020 comparing C (CH₄, CO₂) and N (N₂O, NO, NH₃) trace gas fluxes from Lolium perenne and Trifolium repens dominated montane grasslands with and without vole bioturbation and with and without slurry application, whereby, with regard to the latter, we further differentiated between acidified and non-acidified slurry. Vole bioturbation significantly (p < 0.05) increased soil NO and NH₃ emissions, while N₂O fluxes were only significantly (p < 0.05) enhanced in vole affected grassland patches following slurry application (+17%). Effects of vole bioturbation on CH₄ fluxes were non-significant, while slurry application significantly reduced CH₄ uptake. Compared to applications of non-acidified slurry, application of acidified slurry significantly (p < 0.05) reduced NH₃ volatilization by approx. 38% and 50%, for vole and non-vole affected grassland patches, respectively. A significant effect of acidified slurry application on soil NO emissions was only observed for vole affected grassland patches. Significant (p < 0.05) reductions in aboveground net primary productivity and reduced plant N uptake are likely the main mechanisms explaining the stimulation of gaseous N losses following slurry application. Long-term measurements are needed to better understand effects of vole bioturbation on grassland soil C and N cycling and ecosystem GHG balance.

Responses of small mammals to habitat characteristics in Southern Carpathian forests

Compared to Northern Carpathians, the small mammal fauna of Southern Carpathian forests is poorly known, with no data on habitat use; our study seeks to fill this gap. To this end, we conducted a survey in the Southern Carpathians for five years, assessing habitat use by small mammals in forests along an elevational gradient. Trapping was done using live traps set in transects at elevations between 820 and 2040 m. For each transect we evaluated variables related to vegetation structure, habitat complexity, and geographical location. We considered abundance, species composition and species richness as response variables. The rodents Apodemus flavicollis and Myodes glareolus and the shrew Sorex araneus were common and dominant. Their abundance were positively correlated with tree cover, the best explanatory variable. Responses to other variables were mixed. The strong divergence in the relative habitat use by the three most abundant species may act as a mechanism that enables their coexistence as dominant species, exploiting the same wide range of habitat resources. Overall, habitat use in our study area was similar to that reported from Northern Carpathians, but we found also important differences probably caused by the differences in latitude and forest management practices.

Resource selection of a montane endemic: Sex-specific differences in white-bellied voles (Microtus longicaudus leucophaeus)

Resources that an individual selects contrasted against what is available can provide valuable information regarding species-specific behavior and ecological relationships. Small mammals represent excellent study organisms to assess such relationships. Isolated populations that exist on the edge of a species’ distribution often exhibit behavioral adaptations to the extremes experienced by a species and can provide meaningful insight into the resource requirements of the species. We deployed radio transmitters in a peripheral population of the long-tailed vole (Microtus longicaudus) during the mating season. We developed models of resource selection at multiple scales (within home range and patch). We found voles generally selected areas close to water and roads and consisting of high understory vegetation primarily composed of grasses. Resource selection varied between sexes suggesting different resource needs during the breeding season. The differential resource needs of voles might be a result of the energetic requirements for reproduction and are representative of a promiscuous or polygynous mating system.

Impacts of changes in vegetation on saturated hydraulic conductivity of soil in subtropical forests

Saturated hydraulic conductivity (K_s) is one of the most important soil properties that determines water flow behavior in terrestrial ecosystems. However, the K_s of forest soils is difficult to predict due to multiple interactions, such as anthropological and geomorphic processes. In this study, we examined the impacts of vegetation type on K_s and associated mechanisms. We found that K_s differed with vegetation type and soil depth, and the impact of vegetation type on K_s was dependent on soil depth. K_s did not differ among vegetation types at soil depths of 0-10 and 20-30 cm, but was significantly lower in managed forest types (mixed evergreen broad-leaved and coniferous forests, bamboo forests, and tea gardens) than native evergreen broadleaf forests at a depth of 10-20 cm. Boosted regression tree analysis indicated that total porosity, non-capillary porosity, and macro water-stable aggregates were the primary factors that influenced K_s. Our results suggested that vegetation type was a key factor that influences hydraulic properties in subtropical forest soils through the alteration of soil properties, such as porosity and macro water-stable aggregates.