Der Brotkäfer aus der freien Natur

Ohne Zusammenfassung     

Verfuch einer Bestimmung des allgemeinen objektiven forstlichen Zinsfuszes

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Beitrag zum Crassieren von Waldbahnen und Straszen

Ohne Zusammenfassung     

Cortisol release and heart rate variability in sport horses participating in equestrian competitions

Equestrian competitions require both physical activity and mental adaptation in horses. Cortisol, heart rate, and heart rate variability (HRV) are accepted stress parameters and, in this study, have been determined in horses (n = 13) participating in equestrian competitions for up to 3 consecutive days. Participation in competitions caused an increase in salivary cortisol concentrations (e.g., on day 1 from 1.0 ± 0.2 before to 2.2 ± 0.4 ng/mL after the competition, days 1 and 2: P < 0.001, day 3: P < 0.05) and an increase in heart rate (days 1 and 2: P < 0.001, day 3: P = 0.01). A consistent decrease in HRV occurred only in response to the final competition on day 3 (P < 0.01). When horses competing in dressage and show jumping were compared, cortisol release and HRV did not differ between groups, but after the competition, heart rate was lower in dressage than in show jumping horses (P < 0.05). Heart rate increased not only during the actual competition but already when horses were prepared in their stables (e.g., day 1: ?60 minutes, 38.6 ± 2; ?5 minutes, 77 ± 7; competition, 81 ± 10 beats per minute; P < 0.01). In conclusion, participation in equestrian competitions caused an increase in cortisol release and heart rate and a decrease in HRV variables. However, competitions were not a major stressor compared with other anthropogenic challenges such as transport, to which horses are exposed regularly.     

Differences in Virulence and Genomic Features of Strains of 'Candidatus Phytoplasma mali', the Apple Proliferation Agent

ABSTRACT Root and shoot samples from 24 symptomatic or nonsymptomatic apple trees infected with 'Candidatus Phytoplasma mali' were collected at different locations in Germany and France and used to inoculate rootstock M11 top grafted with cv. Golden Delicious. Inoculated trees were monitored over a 12-year period for apple proliferation (AP) symptoms and categorized as not or slightly, moderately, or severely affected. Based on symptomatology, the phytoplasma strains were defined as being avirulent to mildly, moderately, or highly virulent. Determination of phytoplasma titers by quantitative polymerase chain reaction (PCR) with DNA from roots revealed similar phytoplasma concentrations in all virulence groups. Molecular characterization of the strains by differential PCR amplification with five sets of primers resulted in 13 profiles. Six strains that were maintained in periwinkle and tobacco were molecularly characterized in more detail. The genome sizes of these strains as determined by pulsed-field gel electrophoresis using yeast chromosomes as size references ranged between 640 and 680 kb. Cleavage of the chromosome with the rare cutting restriction enzymes ApaI, BamHI, BssHII, MluI, and SmaI resulted in macro fragment patterns distinctly different in all strains. Similar results were obtained by Southern blot hybridization with three probes derived from strain AT. Differential PCR amplification at an annealing temperature of 52 degrees C using eight primer pairs derived from strain AT revealed heterogeneity of target sequences among all strains. Based on these results, there is considerable variability in virulence and genomic traits in 'Ca. P. mali'. However, correlations between molecular markers and virulence or phytoplasma titer could not be identified.     

<Emphasis Type="Italic">Fusarium</Emphasis> species and mycotoxin profiles on commercial maize hybrids in Germany

High year-to-year variability in the incidence of Fusarium spp. and mycotoxin contamination was observed in a two-year survey investigating the impact of maize ear rot in 84 field samples from Germany. Fusarium verticillioides, F. graminearum, and F. proliferatum were the predominant species infecting maize kernels in 2006, whereas in 2007 the most frequently isolated species were F. graminearum, F. cerealis and F. subglutinans. Fourteen Fusarium-related mycotoxins were detected as contaminants of maize kernels analyzed by a multi-mycotoxin determination method. In 2006, a growth season characterized by high temperature and low rainfall during anthesis and early grain filling, 75% of the maize samples were contaminated with deoxynivalenol, 34% with fumonisins and 27% with zearalenone. In 2007, characterized by moderate temperatures and frequent rainfall during the entire growth season, none of the 40 maize samples had quantifiable levels of fumonisins while deoxynivalenol and zearalenone were detected in 90% and 93% of the fields, respectively. In addition, 3-acetyldeoxynivalenol, 15-acetyldeoxnivalenol, moniliformin, beauvericin, nivalenol and enniatin B were detected as common contaminants produced in both growing seasons. The results demonstrate a significant mycotoxin contamination associated with maize ear rots in Germany and indicate, with regard to anticipated climate change, that fumonisins-producing species already present in German maize production may become more important.     

Dry coniferous forest restoration and understory plant diversity: The importance of community heterogeneity and the scale of observation

Maintaining understory plant species diversity is an important management goal as forest restoration and fuel reduction treatments are applied extensively to dry coniferous forests of western North America. However, understory diversity is a function of both local species richness (number of species in a sample unit) and community heterogeneity (beta diversity) at multiple spatial scales, while studies of restoration treatment effects often only examine local species richness at one or two spatial scales. We studied experimental thinning and prescribed fire treatment effects on understory plant species richness and community heterogeneity at three spatial scales using additive diversity partitioning. We also evaluated treatment effects on understory plant species colonization and extirpation at two spatial scales. There was no evidence that active restoration treatments reduced species richness or increased local extirpation of species. Restoration treatments significantly increased herbaceous species richness at the treatment-unit level primarily by increasing community heterogeneity among sampling points within the units. The combination of thinning and burning produced the greatest increase in community heterogeneity, and increased colonization by species that were not sampled prior to treatment. These results suggest that restoration treatments designed primarily to reduce fire hazard and promote sustainable conditions in these fire-adapted ecosystems can also increase community heterogeneity and facilitate colonization by new understory species without significant local extirpation of extant species.     

Mulching effects on vegetation recovery following high severity wildfire in north-central Washington State,USA

Straw mulch application after high severity wildfire has gained favor in recent years due to its efficacy in reducing soil erosion hazards. However, possible collateral effects of mulching on post-fire vegetation recovery have received relatively little study. We assessed mulching effects on plant cover and species richness, tree seedling establishment, and exotic species densities in the second year following the 2006 Tripod Wildfire in north-central Washington State, USA, by observing vegetation responses to spatial variability in mulch cover and depth. Mulch cover averaged about 35%, with a median depth of 0.5 cm. Vegetation recovery was generally slow, with median plant cover of only 10%. Tree seedling densities were low and spatially variable. Vegetative cover, species richness, and seedling densities all declined with increasing elevation. Mulch cover was positively associated with plant cover, plant species richness, and conifer seedling densities when second year mulch cover did not exceed 40%. Only when mulch cover exceeded 70% did mulching begin to negatively affect vegetation recovery relative to areas with no mulch. Vegetation responses to mulch depth were minimal at depths under 3 cm, but quite strong when mulch depth exceeded 5 cm. Exotic plant frequency and density were positively associated with mulch cover, but exotic plant cover was low on average (<1%). In this study, mulch added significant cover to sites with slow natural recovery of vegetation, thereby likely reducing erosion hazard. Mulching also appears to have facilitated native plant recovery and conifer seedling establishment except at very high application levels, easing management concerns about longer-term impacts of mulching treatments on post-fire vegetation recovery.     

Correlation between charring rate and oxygen permeability for 12 different wood species

The charring rates of 12 different wood species originating from Europe and the tropics with densities ranging from 350 to 750kg/m³ were investigated to obtain clues on their fire resistance behavior. This was done by measuring the thickness of the charred layer after a 30-min exposure to the standard fire ISO 834-1. No correlation was observed between charring rate and density. In search of another physical property that could be used as an indicator of fire resistance, the oxygen permeabilities of the selected wood types were measured. A strong correlation between oxygen permeability perpendicular to the wood fiber direction and charring rate was found, which is quite straightforward given that oxygen is the necessary component to enable smoldering and ignition, both affecting the charring rate. It seems that oxygen permeability is potentially more suitable as a parameter to evaluate the fire resistance of char-sensitive wooden constructions, rather than density. No general preference of the tree ring orientation from 0° (tangential) to 45° and 90° (radial) was found for these measurements. The publication of this article was made possible by an Emachu Research Fund. The authors are grateful for the fund.