Analysing land-cover changes in relation to environmental variables in Hesse,Germany

Land-use and land-cover changes affect ecological landscape functions and processes. Hence, landscape ecologists have a central interest in a comprehensive understanding of such changes. Our study focuses on the relationships between environmental conditions and agricultural land-cover changes. We present a method to (i) characterise the major spatial-temporal processes of land-cover changes, (ii) identify the correlations between environmental attributes and land-cover changes and (iii) derive potential environmental drivers of land-cover changes in a German marginal rural landscape. The method was applied to study land-cover dynamics from 1945 to 1998 in the districts of Erda, Steinbrücken and Eibelshausen, situated in the marginal rural landscape of the Lahn-Dill Highlands, Germany. We employed land-cover data gained by the interpretation of multi-temporal aerial photographs. Various environmental variables were introduced into the analyses. We identified physical landscape attributes (elevation, slope, aspect, available water capacity and soil texture) and structural landscape dimensions (patch size, patch shape and distance between patch and nearest settlement). With the aid of GIS, K-means partitioning and canonical correspondence analysis, we investigated land-cover trajectory types, land-cover transitions at individual time intervals and their relationships to these environmental variables. Our results show that, between 1945 and 1998, land-cover changes correlated with the physical attributes of the underlying landscape. On the other hand, the structural landscape dimensions correlated with land cover only in periods of minor land-cover changes (1972–98). Greater diversity of physical landscape attributes is correlated with greater land-cover dynamics. Besides the important influence of socio-economic factors, land-cover changes in the study areas took place within the relatively stable physical constraints of the underlying landscape.This revised version was published online in May 2005 with corrections to the Cover Date.     

Fetal responses to different methods of electrocution of pregnant sows

The fetal stress responses in sows euthanized by electrical current during their second and last trimester of pregnancy (G1 and G2) were evaluated. Three methods of euthanasia of pregnant sows generally applicable to cases of epizootic or emergency slaughter were investigated: 1. conventional application of electrical current to the head and heart (HH); 2. application of electrical current to the head, heart and the uterus (HHU); 3. application of electrical current to the head, heart and from the upper body to the vagina (HHV). Fetuses were delivered by cesarean section at intervals of 3 to 4 minutes and remained attached to the sow by the umbilical cord. Fetal vitality, reflexes, heart rate, blood pressure, rectal body temperature, intracardial arteriovenous pCO2, pH and lactic acid were monitored for a period of 30 minutes. No method was found to kill the fetal pigs immediately. In fetuses at G1 there were no significant differences between the HH and HHU and HHV methods. Fetuses at G2 showed a significantly faster decrease in heart rate and blood pressure as well as a shorter period of time for the absence of fetal body movements and reflexes for the HHT method, compared to the other methods. Since it is not yet known to what extent the fetal pig experiences pain and suffering, the prolonged process of dying for the in utero fetus due to hypoxia which includes struggling and gasps is inconsistent with criteria for humane euthanasia and animal welfare.     

Development and in vitro characterization of canine CD40-Ig

We recently reported that blockade of the CD40-CD154 ligand interaction with the cross-reacting mouse anti-human CD154 antibody, 5c8, together with donor-specific transfusion led to enhanced but not completely successful engraftment in a canine model of DLA-identical marrow transplantation after 100cGy total body irradiation (TBI). In order to improve the transplantation outcomes, we sought to develop a canine-specific reagent. To that end, we fused the extracellular domain of the canine CD40 with a mouse IgG2a Fc tail and tested the immunosuppressive effectiveness of the fusion protein in mixed leukocyte reactions. The extracellular domain of canine CD40 was fused with the Fc portion of mouse IgG2a in a pcDNA3.1+vector. Dhfr-deficient CHO cells were co-transfected with the CD40-Ig vector and a dhfr-containing vector. Stable, high producing clones were selected under increasing methotrexate concentrations. The fusion protein was purified, tested in mixed leukocyte reactions, and its immunosuppressive effect compared to that of the anti-CD154 antibody 5c8. The transfected cell line produced a CD40-Ig dimer whose identity was confirmed by mass spectroscopy. The purified canine CD40-Ig blocked mixed leukocyte reactions at a concentration of 1nM, which was 10 times more effective than the anti-CD154 antibody. Canine CD40-Ig is more immunosuppressive than the anti-human CD154 antibody 5c8 in canine mixed leukocyte reactions and may be more effective in vivo in a model of marrow transplantation.     

Measurement of redox potential inside a suction probe

Ceramic suction probes were combined with internal redox electrodes in order to reduce the deviation between site parallels, and to relate redox potential measurements directly to the solution analyzed chemically. In a laboratory experiment soil material was water‐saturated for 49 days and temporal changes of redox potential and pH outside and inside the ceramic suction probes were recorded. Furthermore, iron concentrations inside the ceramic cups were detected. Results indicate that a device combining ceramic suction probes and redox electrodes is in principal possible. However, the device used here could not reduce the deviation between site replications compared to free installed redox electrodes. Increasing iron concentrations due to decreasing redox potentials outside and inside the ceramic suction probes indicate that the soil water iron dynamic is at least partly measurable using this device.<?show $6#>     

Relation between respiration,ATP content,and Adenylate Energy Charge (AEC) after incubation at different temperatures and after drying and rewetting

Temperature, drying, and rewetting are important climatic factors that control microbial properties. In the present study we looked at the respiration rates, adenosine 5′‐triphosphate (ATP) content, and adenylate energy charge (AEC) as a measure for energy status of microbial biomass in the upper 5 cm of mineral soils of three beech forests at different temperatures and after rewetting. The soils differed widely in pH (4.0 to 6.0), microbial biomass C (92 to 916 μg (g DW)^—1) and ATP content (2.17 to 7.29 nmol ATP (g DW)^—1). The soils were incubated for three weeks at 7 °C, 14 °C, and 21 °C. After three weeks the microbial properties were determined, retaining temperature conditions. The temperature treatment did not significantly affect AEC or ATP content, but respiration rates increased significantly with increasing temperature. In a second experiment the soils were dried for 12 hours at 40 °C. Afterwards the soils were rewetted and microbial properties were monitored for 72 hours. After the drying, respiration rates dropped below the detection limit, but within one hour after rewetting respiration rates increased above control level. Drying reduced AEC by 16 % to 44 % and ATP content by 47 % to 78 %, respectively. Rewetting increased AEC and ATP content significantly as compared to dry soil, but after 72 hours the level of the controls was still not reached. The level of AEC values indicated dormant cells, but ATP content increased. These results indicate that the microbial carbon turnover was not directly linked to microbial growth or microbial energy status. Furthermore our results indicate that AEC may describe an average energy status but does not reflect phases of growing, dormant, or dying cells in the complex microbial populations of soils.     

Spatial and temporal variability of physical properties of Aquands under different land uses in southern Chile

The aquands found in southern Chile are derived from volcanic ash and contain high levels of organic matter. Due to the presence of an impermeable stratum, they have shallow soil profiles, which induce waterlogging for several months each year. These fragile soils, locally known as ‘Ñadi’, cover an area of 475 000 hectares and have undergone intensive land use changes, which have affected the soil physical properties. These are still not well understood but are relevant for the design of efficient drainage systems. The aim of this research was to analyse the impact of the land use change in Ñadi soils on the spatial and temporal variability of their soil physical properties. For the land use change from secondary native forest (sNF) to naturalized grassland (NG), the effective soil depth was measured at defined points. Time‐ and space‐dependent changes of water‐table depth and penetration resistance were recorded. Volumetric water content and soil temperature were measured with sensors installed at three depths and the water retention curve and air permeability at these depths were also determined. The changes in land use over time have induced a reduction in soil depth. Soils under NG showed a smaller soil water storage capacity, air capacity and permeability compared with soils under sNF, as well as waterlogging during winter and greater mechanical strength and soil profile temperatures during summer. Therefore, the land use change affected the spatial and temporal variability of soil physical functions across the field.     

Enhancing the regeneration of compacted forest soils by planting black alder in skid lane tracks

Soil compaction due to the use of heavy machinery for timber harvesting has become a widespread problem in forestry. However, only few studies deal with the regeneration of compacted forest soils. In the present study, we examined the potential of accelerating soil regeneration by planting black alder trees (Alnus glutinosa (L.) Gaertn.) in skid lane tracks. In 2003, seedlings were planted into the rut beds of severely compacted skid lanes in two Swiss forest sites. In addition, some of the ruts were filled with compost. In 2009 and 2010, we assessed the success of these measures by analysing physical parameters of soil structure (bulk density, total and coarse porosity and air permeability), root densities and tree growth. Tree growth was exceptionally strong on the skid lanes. Total and coarse soil porosity and air permeability showed significant increase in planted skid lanes as compared to untreated control subplots, approaching values found for untrafficked soil in the immediate vicinity. All soil physical parameters were closely correlated to root mass density. Compost application enhanced tree growth and soil structure regeneration on one site, but had a retarding effect on the other site. Planting black alders has great potential as an environmentally friendly measure to accelerate the structural regeneration of compacted forest soils in temperate humid climates.     

Evaluating the effect of plant water availability on inner alpine coniferous trees based on sap flow measurements

Climate simulations anticipate an increase in mean summer temperature with synchronous decrease in summer precipitation during the course of the current century in Central Europe. As a consequence, transpiration of forest trees and stands may be altered along with soil water availability. In this study, the effect of reduced plant water availability to conifers was investigated into an open Pinus sylvestris forest (Erico-Pinetum typicum; P. sylvestris 60 %, Picea abies 20 %; and Larix decidua 20 %) within the inner alpine dry valley of the Inn River in Tyrol, Austria. For reducing plant water availability, we installed a transparent roof construction above the forest floor to prevent precipitation to reach the soil. The roofed area covered 240 m² and included 10 trees. A respective number of 11 trees served as controls in the absence of any manipulation. Roofing significantly reduced plant water availability as indicated in lower predawn needle water potentials. Sap flow density (Q _s) was 63, 47, and 24 % lower in roofed P. sylvestris, P. abies, and L. decidua trees, respectively, as compared to control trees. Our findings suggest that P. sylvestris and P. abies behaves “isohydric” as they close their stomata relatively early under conditions of reduced plant water availability and thus stabilize their water relations, whereas L. decidua behaves “anisohydric” and maintains high transpiration rates.     

Forest transpiration—targeted through xylem sap flux assessment versus hydrological modeling

The assessment of forest transpiration rates is crucial for determining plant-available soil water consumption and drought risk of trees. Xylem sap flux measurements have been used increasingly to quantify stand transpiration in forest ecosystems. Here, we compare this empirical approach with hydrological modeling on the basis of a stand transpiration dataset of adult beech (Fagus sylvatica), which was acquired across Bavaria, Germany, at eight forest sites. Xylem sap flux sensors were installed in five dominant trees each. Two tree to stand upscaling approaches, related to site-specific (1) sapwood area or (2) to leaf area index, were compared. The outcome was examined each in relation to process-based stand hydrological modeling, using LWF-BROOK90. Distinct relationships between tree diameter at breast height (1.30 m) and sapwood area-weighted sap flux along the radial profile became apparent across the study sites, confirming a generic allometric basis for stand-level upscaling of transpiration. The two upscaling approaches did not differ in outcome, representatively covering stand structure for comparison with modeling. Differential analysis yielded high agreement between the empirical and modeling approaches throughout most of the study period, although LWF-BROOK90 tended to overestimate sap flux measurements under low soil moisture. The two empirical approaches proved reliable for even-aged beech stands, as performance under high stand-structural heterogeneity awaits clarification. Findings advance stand-level hydrological modeling regarding coverage of stomatal behavior during temporary limitation in water availability.