Habitat specialists and generalists drive homogenization and differentiation of temperate forest plant communities at the regional scale     

Tobias Naaf  Monika Wulf 《Biological conservation》2010,143(4):848-50

In European temperate forests, changes in the compositional similarity among local plant communities (beta diversity) have rarely been studied due to the lack of adequate baseline data. Several studies, however, report the spread of common, generalist species or a decline in specialized, rare species. Both processes may lead to increased similarity among communities, i.e., biotic homogenization.To quantify changes in beta diversity, we resampled the herb layer composition of ancient broadleaf forests at 175 semi-permanent plots distributed across the Weser-Elbe region in NW Germany 20 years after first sampling. We hypothesized that beta diversity would have decreased on average as a result of a spread of habitat generalists and a decline in habitat specialists.After two decades, the forest communities did not yet exhibit severe biotic impoverishment, although there was a broad trend towards homogenization. The actual magnitude of change depended on which beta diversity measure was applied. The downward trend was primarily the result of the spread of native species that are able to tolerate broad pH and moisture ranges. A distinction between forest specialists (closely tied to forest habitats) and generalists (also found in open habitats) did not help explain changes in beta diversity. The study shows that on the regional scale and in habitats not yet threatened by the invasion of alien species, shifts in native species can promote biotic homogenization.  相似文献   

Phosphorus forms as affected by abandoned anthills (Formica polyctena Förster) in forest soils: sequential extraction and liquid-state 31P-NMR spectroscopy     

Søren M. Kristiansen  Wulf Amelung  Wolfgang Zech 《植物养料与土壤学杂志》2001,164(1):49-55

Ants are known to concentrate phosphorus (P) inside their nests via collection of food and litter. To elucidate the possible effects on long-term availability of soil P, five anthills abandoned by Red wood ant (Formica polyctena Förster) > 5—20 years ago were characterized for soil P forms in a temperate Danish deciduous forest. Sequentially extracted P fractions and liquid-state ³¹P nuclear magnetic resonance (NMR) spectra were obtained on surface samples (0—10 cm) from abandoned anthills and adjacent topsoil; in addition one representative soil profile in an abandoned anthill was investigated. The results show that different inorganic and all organic P fractions were enriched by a factor of 2.0—3.3 inside anthills relative to the surrounding soil. The soil underneath the abandoned anthill had higher P contents until 50-cm depth. Phosphorus composition was less affected by former anthill construction. Only the younger anthills revealed a preferential accumulation of labile organic P forms such as Na-HCO₃ extractable P or diester P. The accumulation of the stable and moderate labile P forms, however, persisted for ≥ 20 years after abandonment. We concluded that former ant activity enhanced long-term P availability of soil due to high local P inputs, whereas changes of the P form distribution lasted 5—10 years after nest abandonment.  相似文献   

Beziehungen zwischen Klimafaktoren und C-, N-Pools in Partikelgrößen-Fraktionen zonaler Steppenböden Rußlands     

Andrej Rodionov  Wulf Amelung  Inga Urusevskaja  Wolfgang Zech 《植物养料与土壤学杂志》1998,161(5):563-569

Relationships between climatic factors and C, N pools in particle-size fractions of steppe soils, Russia Many soils of the Russian steppe are characterized by high soil organic matter contents and similar parent material. Thus, they are suitable for investigations of a climatic impact on C and N pools. We sampled 10 topsoils of the zonal Russian steppe at 0–10 and about 50–60 cm depth intervals. After particle-size fractionation into clay (<2 μm), silt (2–20 μm), fine sand (20–250 μm) organic C and N concentrations were determined in bulk soils and fractions. The results suggest that especially the older organic matter of the subsoil (in the silt fraction) is correlated with climatic factors. Topsoils show less evidence for climatic influences on C and N pools. As the ratio of mean annual precipitation to potential evaporation (=N/V) increases, C/N ratios decrease in all fractions and, thus, in the bulk subsoil. Obviously the degree of soil organic matter alteration was more pronounced in the order Greyzem (N/V = 1.0) > Chernozem, Phaeozem (N/V = 0.89) > Haplic Kastanozem (N/V = 0.6) > Calcic (N/V = 0.34), and Gypsic Kastanozem (N/V = 0.32). The organic carbon contents of the bulk subsoil are highest in the subsoil of the Chernozem and Phaeozem, and decrease with increasing N/V ratio (i.e., increasing heat input and dryness) to the Calcic Kastanozem. This is accompanied by an increasing enrichment of organic carbon in the silt fractions (r = ?0.99 for the correlation of the C enrichment in silt with N/V).  相似文献   

Short‐term sequestration of slurry‐derived carbon and nitrogen in temperate grassland soil as assessed by 13C and 15N natural abundance measurements     

Bruno Glaser  Roland Bol  Neil Preedy  Kevin B. McTiernan  Matt Clark  Wulf Amelung 《植物养料与土壤学杂志》2001,164(5):467-474

Land application of animal wastes from intensive grassland farming has caused growing environmental problems during the last decade. This study aimed to elucidate the short‐term sequestration of slurry‐derived C and N in a temperate grassland soil (Southwest England) using natural abundance ¹³C and ¹⁵N stable isotope techniques. Slurry was collected from cows fed either on perennial ryegrass (C3) or maize (C4) silages. 50 m³ ha^—1 of each of the obtained C3 or C4 slurries (δ¹³C = —30.7 and —21.3‰, δ¹⁵N = +12.2 and + 13.8 ‰, respectively) were applied to a C₃ soil with δ¹³C and δ¹⁵N values of —30.0 ± 0.2‰ and + 4.9 ± 0.3‰, respectively. Triplicate soil samples were taken from 0—2, 2—7.5, and 7.5—15 cm soil depth 90 and 10 days before, at 2 and 12 h, as well as at 1, 2, 4, 7, and 14 days after slurry application and analyzed for total C, N, δ¹³C, and δ¹⁵N. No significant differences in soil C and N content were observed following slurry application using conventional C and N analysis techniques. However, natural abundance ¹³C and ¹⁵N isotope analysis allowed for a sensitive temporal quantification of the slurry‐derived C and N sequestration in the grassland soil. Our results showed that within 12 hours more than one‐third of the applied slurry C was found in the uppermost soil layer (0—2 cm), decreasing to 18% after 2 days, but subsequently increasing to 36% after 2 weeks. The tentative estimate of slurry‐derived N in the soil suggested a decrease from 50% 2 hours after slurry application to only 26% after 2 weeks, assuming that the increase in δ¹⁵N of the slurry plots compared to the control is proportional to the amount of slurry‐incorporated N. We conclude that the natural abundance tracer technique can provide a rapid new clue to the fate of slurry in agricultural C and N budgets, which is important for environmental impacts, farm waste management, and climate change studies.  相似文献   

Small forest patches as pollinator habitat: oases in an agricultural desert?     

Proesmans  Willem  Bonte  Dries  Smagghe  Guy  Meeus  Ivan  Decocq  Guillaume  Spicher  Fabien  Kolb  Annette  Lemke  Isgard  Diekmann  Martin  Bruun  Hans Henrik  Wulf  Monika  Van Den Berge  Sanne  Verheyen  Kris 《Landscape Ecology》2019,34(3):487-501

Landscape Ecology - Small forest fragments are often the most abundant type of semi-natural habitat in intensive agricultural landscapes. Wild pollinators can use these forest patches as nesting or...  相似文献   

Prevalence and formation of primary cataracts and persistent hyperplastic tunica vasculosa lentis in the German Pinscher population in Germany          下载免费PDF全文

Sophia Pfahler  Julia Menzel  Rolf Brahm  Carsten U. Rosenhagen  Birgit Hafemeister  Uta Schmidt  Wolfgang Sinzinger  Ottmar Distl 《Veterinary ophthalmology》2015,18(2):135-140

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Fungi associated with above-ground portions of declining oaks (Quercus robur) in Germany     

R. D. Kehr  A. Wulf 《Forest Pathology》1993,23(1):18-27

Various disease symptoms on oak (Quercus robur L.) affected by oak decline in northern Germany were examined for fungal colonization. The isolated fungi are evaluated in respect to their possible pathogenic qualities and the results are compared with those of other authors and geographic regions.  相似文献   

Unusual vascular ring anomaly associated with a persistent right aortic arch and an aberrant left subclavian artery in German pinschers     

Julia Menzel  Ottmar Distl   《Veterinary journal (London, England : 1997)》2011,187(3):352-355

The objective of this study was to describe a specific form of persistent right aortic arch (PRAA) in three German pinscher dogs and to analyse the mode of inheritance in the breed. This type of PRAA is characterised by a left retro-oesophageal subclavian artery in combination with a ligamentum arteriosum originating at the aberrant left subclavian artery (PRAA-SA-LA). This rare combination of anomalies has only been reported in two isolated cases in other dog breeds and the occurrence of any form of PRAA was not previously known to occur in the German pinscher. In the present study, 18 cases of this congenital anomaly were ascertained and their high degree of relatedness and inbreeding could be shown through pedigree analysis. Three of the affected dogs underwent further clinical investigations, and post-mortem examination (two cases) and findings at surgery (one case) verified the diagnosis of PRAA-SA-LA. A monogenic autosomal recessive mode of inheritance was not likely.  相似文献   

Pharmacokinetics and tissue concentrations of firocoxib in sows following oral administration     

Michael D. Kleinhenz  Carissa Odland  Todd E. Williams  Yuntao Zhang  Alyson H. Fitzgerald  Pritam K. Sidhu  Larry W. Wulf  Johann F. Coetzee 《Journal of veterinary pharmacology and therapeutics》2020,43(5):491-498

The objectives of this study were to describe the pharmacokinetics of firocoxib following oral (PO) dosing and intravenous (IV) injection in sows. Seven healthy sows were administered 0.5 mg firocoxib/kg IV. Following a 23-d washout period, sows were administered firocoxib at 4.0 mg firocoxib/kg PO. Blood samples were collected at predetermined times for 72 hr after IV and 120 hr after PO administration. Plasma firocoxib concentration was measured using UPLC-MS/MS, and pharmacokinetic analysis was performed using noncompartmental procedures. Tissue firocoxib concentrations were determined at 5, 10 (n = 2/time point), and 21 d (n = 3) after PO administration. The geometric mean half-life following IV and PO administration was 16.6 and 22.5 hr, respectively. A mean peak plasma concentration (Cmax) of 0.06 µg/ml was recorded at 7.41 hr (T_max) after oral administration. Mean oral bioavailability was determined to be 70.3%. No signs of NSAID toxicity were observed on macroscopic and microscopic investigation. Firocoxib was detected in the skin with subcutaneous fat (0.02 µg/g) of one of three sows at 21 days postadministration. Additional work to establish appropriate meat withhold intervals in sows is required. Firocoxib was readily absorbed following PO administration. Further work is needed to better understand the analgesic effects for sows and piglets nursing sows administered firocoxib.  相似文献   

Stress Response of Three-year-old Horse Mares to Changes in Husbandry System During Initial Equestrian Training     

Regina Erber  Manuela Wulf  Jörg Aurich  Sandra Rose-Meierhöfer  Gundula Hoffmann  Mareike von Lewinski  Erich Möstl  Christine Aurich 《Journal of Equine Veterinary Science》2013

For initial training, horses are often transferred from group housing to individual boxes, which is a potential stressor. In this study, salivary cortisol concentrations, locomotion activity, and heart rate (HR) were analyzed and the HR variability (HRV) variables standard deviation of beat-to-beat interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated in 3-year-old mares (n = 8). Mares were transferred abruptly from a group stable with access to a paddock to individual boxes without a paddock and were studied from 4 days before to 5 days after changing the stable. Mares underwent routine equestrian training for young horses. On the days before mares were moved to individual boxes, cortisol concentrations showed a diurnal rhythm with values approximately 0.6 ng/ml in the morning and a decrease throughout the day. When horses were moved to individual boxes, cortisol concentrations increased to 1.8 ± 0.2 ng/ml within 30 minutes and did not return to baseline values within 6 hours (0.7 ± 0.1 ng/ml, P < .05 over time). On the following days, a diurnal rhythm was re-established but at a higher level than before the change of stable. Locomotion activity was higher when mares had access to a paddock than when kept in individual boxes. Heart rate increased for approximately 60 minutes when mares were separated from their group. In conclusion, separating young horses from their group and individual stabling are perceived as stressful.  相似文献