Scale‐dependent biases in species counts in a grassland

Abstract. Numbers of plant species were recorded in species‐rich meadows in the Bílé Karpaty Mts., SE Czech Republic, with the aim to evaluate the sampling error made by well‐trained observers. Five observers recorded vascular plants in seven plots ranging from 9.8 cm² to 4 m² independently and were not time‐limited. In larger plots a discrepancy of 10–20% was found between individual estimates, in smaller plots discrepancy increased to 33%, on average. The gain in observed species richness by combining records of individual observers (in comparison with the mean numbers estimated by single observers) decreased from the smallest plot (27–82% for two to five observers) to the largest one (13–25%). However, after misidentified and suspicious records were eliminated, the gain was much lower and became scale‐independent; two observers added 12% species, on average, and the increase by combining species lists made by three or more observers was negligible (3% more on average). It is concluded that most discrepancies between individual observers were caused by misidentification of rare seedlings and young plants. We suggest that in species‐rich meadows plants should be recorded by at least three observers together and that they should consult all problematic plant specimens together in the field, to minimize errors.     

Using species traits to assess human impacts on near shore benthic ecosystems in the Canadian Arctic

Human activities have the potential to alter the diversity and composition of biological communities in natural environments, which can cause changes in ecosystem functioning. This has led to the development of environmental assessment techniques that take into account species identity, as species can contribute differently to various ecosystem processes. Biological Traits Analysis (BTA) is used to compare the abundances of specific biological traits in samples to produce information about how ecosystem functioning may change across a specific terrestrial or aquatic system. In the present study, BTA was used to assess the influence of municipal wastewater effluent on benthic marine communities in near shore soft sediments in four locations across the Canadian Arctic Territory of Nunavut, Canada. Shifts in trait composition were assessed relative to indicators of sediment enrichment (sediment chlorophyll, organic content, degree of anoxia), and natural variation in habitat characteristics (water depth, porosity, average grain size) at a site receiving wastewater and a reference site in each sampling location. The results indicated a mild enrichment effect of wastewater, as evidenced by changes in trait composition at three of the four sites that received wastewater inputs. However, the amount of variance in trait composition explained by metrics of wastewater enrichment in these locations were generally equal to or lower than the amount of variance explained by sediment characteristics related to natural processes. These results provide greater insight into the underlying causes and consequences of human activities than more traditional methods for environmental impact assessment, and can be directly applied in a management context.     

Investigating the evolution of floras: problems and progress — An introduction

The Cape flora of southern Africa is a remarkable hotspot for plant species diversity and endemism. At a meeting in Zurich in 2004 progress in understanding the evolution of this diversity was reviewed. In this symposium, four papers presenting several of the methods used in this investigation were reported. These papers deal with molecular dating methods, the reconstruction of ancestral habitats, with possible speciation scenarios for the Cape flora, and the importance of the correct sampling strategies.     

Contribution of Val/Ile87 residue in the extracellular domain in agonist-induced current responses of the human and rat P2X7 receptors

Purinergic Signalling - The P2X7 receptor (P2X7R) is an ATP-gated cation channel with a critical role in many physiological and pathological processes, and shows prominent functional differences...