Landscape Ecology – towards a unified discipline?

Contemporary landscape ecology is not unified at all.There are historical, geographical and biological reasons for the lack of unification, as well as differences between science and application. The search for a unified theory of landscape ecology should consider previous concepts such as ‘landscape diagnosis’ and ‘landscape functions’ which were elaborated in Central Europe. Because of the various aspects in a landscape (components, processes, relations), landscape ecology should be regarded as a multidisciplinary, better a transdisciplinary, science where different views and approaches are involved in a holistic manner. The principle of complementarity is helpful to understand and describe the landscape. As a crucial step, the transformation of natural science categories to categories of the human society is brought out. This is realized by land(scape) evaluation and by the elaboration of goals (visions) of landscape development.This revised version was published online in May 2005 with corrections to the Cover Date.     

Single-molecule vibrational spectroscopy and microscopy

Vibrational spectra for a single molecule adsorbed on a solid surface have been obtained with a scanning tunneling microscope (STM). Inelastic electron tunneling spectra for an isolated acetylene (C2H2) molecule adsorbed on the copper (100) surface showed an increase in the tunneling conductance at 358 millivolts, resulting from excitation of the C-H stretch mode. An isotopic shift to 266 millivolts was observed for deuterated acetylene (C2D2). Vibrational microscopy from spatial imaging of the inelastic tunneling channels yielded additional data to further distinguish and characterize the two isotopes. Single-molecule vibrational analysis should lead to better understanding and control of surface chemistry at the atomic level.     

Inducing and viewing the rotational motion of a single molecule

Tunneling electrons from the tip of a scanning tunneling microscope were used to induce and monitor the reversible rotation of single molecules of molecular oxygen among three equivalent orientations on the platinum(111) surface. Detailed studies of the rotation rates indicate a crossover from a single-electron process to a multielectron process below a threshold tunneling voltage. Values for the energy barrier to rotation and the vibrational relaxation rate of the molecule were obtained by comparing the experimental data with a theoretical model. The ability to induce the controlled motion of single molecules enhances our understanding of basic chemical processes on surfaces and may lead to useful single-molecule devices.     

The Influencing Factor of In Vitro Fertilization and Embryonic Transfer in the Domestic Fowl (Gallus domesticus)

This study was conducted to explore the influencing factors of ova in vitro fertilization (IVF) and transfer of the fertilized ova into the oviduct of recipient hens. The efficiency of fertilization was compared using three aspects: (i) the different time of ova collection and transfer, (ii) egg‐laying period of recipient hen; and (iii) semen volume. The following results are observed: 72%, 40% and 0% of ova were found in ovarian sac in 30～40 min, 50～60 min and more than 90 min post‐oviposition, respectively; 20%, 18%, 14% and 5.8% of ova were fertilized with 0.1, 0.2, 0.5 and 1.0 ml semen, respectively; and 33% and 100% of healthy chickens were hatched from fertile ova with 0.1 and 0.5 ml of semen, respectively. All oocytes obtained from ovary and mid‐oviduct were unfertilized. Embryos were transferred into recipient hens 30 min ± 10 min post‐oviposition, and 70% of shelled eggs were produced. There were no eggs produced in the other transfer times. This demonstrated that live chicken can be obtained by IVF of ova collected shortly after oviposition. It was important that the ovum was transferred into the oviduct infundibulum of recipient hens immediately or shortly after oviposition.     

Profitability of Carbon Sequestration in Western Rangelands of the United States

Concerns over climate change have increased interest in carbon sequestration in agricultural lands. While the per-hectare carbon capture potential of rangelands is less than either cropland or forests, existing research suggests modest changes in carbon storage on rangelands can potentially alter the global carbon cycle. This paper examines the potential firm-level revenues from voluntary carbon offset programs, such as the Chicago Climate Exchange (CCX) Rangeland Soil Carbon Offset program. We estimate revenues for short-term voluntary offsets given historical prices and prices projected with potential cap-and-trade legislation. We also estimate revenues assuming 100-yr offsets are required to meet international sequestration standards. Simulation results indicate a relatively wide range of modest revenues from recent CCX contracts and carbon prices. The analysis suggests that recent carbon prices or low-end projected prices from cap-and-trade legislation are not likely to encourage producer participation. Medium and high carbon price projections for cap-and-trade legislation may make carbon sequestration a more attractive option for rangeland managers, but given potential requirements for projects to meet international guidelines for greenhouse gas offset projects, many issues remain before range managers may be interested in carbon sequestration as an enterprise.     

Sagebrush Control: At What Canopy Cover Is It Economically Justified?

We determine the economic threshold level for big sagebrush control based on 18 yr of forage-response data from an experiment conducted in Carbon County, Wyoming. We analyze the impacts of climatic variables and treatment site characteristics, such as sagebrush abundance levels, precipitation, and understory composition, on forage response and threshold level. We find that sagebrush canopy cover levels, April precipitation, May soil moisture, and understory composition are statistically significant factors in explaining forage response to sagebrush treatment. Forage yield across treated and untreated plots for 10 canopy cover levels, ranging from 4% to 40%, are analyzed via panel data regression techniques. We further investigate the impact of variability in precipitation and understory characteristics on economic outcomes of sagebrush control by analyzing three scenarios. Scenario 1 uses actual forage response data that include all variability from precipitation and understory composition. Scenario 2 uses regression-predicted yields across plots assuming average precipitation and soil moisture conditions. Scenario 3 uses regression-predicted yields assuming average precipitation, soil moisture, and understory characteristics across plots. Net present values based on value of grazing (for estimated yield differences between treated and untreated plots assuming 50% forage utilization) compared to treatment cost across sagebrush cover levels are estimated across these three scenarios. Results indicate that the economic threshold level of sagebrush infestation for the study period was between 8% and 24% for the analyzed scenarios. This indicates variability in precipitation and understory composition impact forage response and the resulting economics of sagebrush control. We conclude that range managers should consider potential control site characteristics and long-range weather forecasts when contemplating sagebrush control.     

Effects of 2.0% end-tidal isoflurane with and without atropine prior to dexmedetomidine administration on cardiovascular variables in dogs

The purpose of this study was to determine the cardiovascular effects of 2.0% end‐tidal isoflurane in dogs administered dexmedetomidine (DEX). Using a randomized crossover design and allowing at least 2 weeks between treatments 12 adult hound dogs of either sex weighing 22 ± 1.7 SD kg were anesthetized by face mask administration of either sevoflurane or isoflurane to facilitate instrumentation prior to administration of treatment drugs. Dogs were intubated and instrumented to enable measurement of heart rate (HR), systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures, mean pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), pulmonary arterial temperature (TEMP), and cardiac output (CO) via thermodilution using 5 mL of 5% dextrose, and recording the average of three replicate measurements. Cardiac index (CI) and systemic (SVR) and pulmonary vascular resistances were calculated. Following completion of instrumentation, dogs were allowed to recover for 40 minutes. After collection of baseline data, dogs were administered one of four treatments at T‐10 minutes prior to injection of DEX (500? g M^–2 IM): 1) saline (SAL); 2) atropine [ATR, 0.02 (n = 6) or 0.04 (n = 6) mg kg^–1 IM]; 3) ISO (2.0% end tidal concentration); or 4) ISO + ATR. Cardiovascular data were collected at T‐20 and T‐5 minutes prior to administration of DEX, and at 5, 10 , 20, 30, 40, and 60 min following DEX. Data were analyzed using anova for repeated measures with post‐hoc differences between means identified using Bonferroni's method (p < 0.05). Differences in ATR dose were not found to be significant and thus results for ATR dose groups were pooled. Administration of SAL (dexmedetomidine alone) was associated with decreases in HR and CO and increases in SAP, MAP, DAP, CVP, and SVR. Administration of ATR was associated with an increase in HR and CO compared with SAL. Administration of ISO was associated with an increase in HR and a decrease in SVR, MAP and CVP compared with SAL. Administration of ISO + ATR was associated with effects similar to that of ISO or ATR alone. We conclude that administration of ISO reduces the increase in SVR associated with administration of DEX and does not adversely affect CO.     

Landscape Diagnosis on Different Space and Time Scales – A Challenge for Landscape Planning

Landscape diagnosis provides a bridge between scientific knowledge and socio-economic issues that is needed to meet the demands of sophisticated landscape planning and management. The diagnostic assessment of landscape functions (capacities, goods and services supported by the landscape) at different spatio-temporal scales is a valuable tool that can solve the transformation problem. A variety of landscape classification systems – including biophysical and landscape units – can be applied as a spatial reference system. Examples are described from the multitude of approaches to assess landscape functions that can be employed in landscape diagnosis. The theoretical and methodological aspects of the approach are illustrated using examples both from Germany and the Czech Republic. The examples focus on landscape functions such as groundwater recharge, regulation of water balance, and resistance to wind erosion. In addition, the rarity of and threats to landscape types, landscape aesthetic values, and the landscape character and landscape persistence are discussed.     

Absence of Sperm Factors as in the Parthenogenesis Does Not Interfere on Bovine Embryo Sensitiveness to Heat Shock at Pre‐Implantation Stage

Oocyte has been considered the major contributor for embryo thermo‐tolerance. However, it was shown that sperm factors can be transferred to the oocyte during fertilization, raising the question of whether the absence of such factors could interfere on embryo thermo‐tolerance. In this study, we used parthenogenesis to generate bovine embryos without spermatozoa in order to test whether the absence of sperm factors could influence their thermo‐sensitiveness at early stages. In vitro fertilized (IVF) and parthenogenetic (PA) embryos at 44 h post‐insemination/chemical activation were exposed to 38.5°C (control) or 41°C (heat shock) for 12 h and then developed for 48 h and up to blastocyst stage. Apoptosis index and expression of PRDX1, GLUT1, GLUT5 and IGF1r genes in blastocysts derived from heat‐shocked embryos were also evaluated. The heat shock decreased the blastocyst rate at day seven (p < 0.05) for IVF embryos and at day eight (p < 0.01) for both IVF and PA embryos. Total cell number was not affected by heat shock in IVF and PA blastocysts, but there was an increased proportion (p < 0.05) of apoptotic cells in heat‐shocked embryos when compared to controls. There was no interaction (p > 0.05) between method of activation (IVF and PA) and temperature (38.5°C or 41.5°C) for all developmental parameters evaluated. Expression of GLUT1 gene was downregulated (p < 0.05) by heat shock in both IVF and PA blastocyst whereas expression of GLUT5 and IGF1r genes was downregulated (p < 0.05) by heat shock in PA blastocysts. Those data show that the heat shock affects negatively the embryo development towards blastocysts stage, increases the apoptotic index and disturbed the expression of some genes in both IVF and PA embryos, indicating that the presence or absence of sperm factors does not influence the sensitivity of the bovine embryo to heat shock.