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The great sensitivity of the response of alpine plant community to climate change makes the identification of these responses important. In 2007, we conducted a reciprocal translocation experiment on 100 × 100 × 40 cm coherent turf and soil along an elevation gradient of 3200–3800 m on the south slope of Qilian Mountains northeast of the Qinghai-Tibetan Plateau. The aim was to understand the warming/cooling effects on the alpine ecosystem where treatments were simulated by donor elevations below/above receptors. Translocated vegetation comprised the Kobresia meadow at 3200 m, deciduous shrub meadow at 3400 m, forbs meadow at 3600 m, and sparse vegetation at 3800 m. The 5 × 5 cm grid method (50 × 50 cm, 100 grids) was used for surveying plant species absolute abundance in translocated quadrats. Results showed that species richness and Shannon-Weaver index of Kobresia meadow increased significantly (P <0.05) when translocated to 3400 m. Shannon-Weaver index of shrub meadow declined, while shrub species abundance responded slightly both to warming and cooling treatments. Both species richness and Shannon-Weaver index of forbs meadow and sparse vegetation were enhanced evidently at 3200 m and 3400 m. Four groups were identified by non-metric multidimensional scaling based on receptor elevation. Responses of the alpine plant community and the function group appeared to be specific to climate magnitude and specific to function type, respectively. Correlation indicated that climatic factors played a much more important role than soil in the response of the alpine plant community. Four vegetation types were sensitive to climate change, while Kobresia meadow behaved flexibly. Global warming would depress sedges but favor legumes and graminoids.
In stream corridors, driftwood represents mainly a dead vegetation biomass and diverse artificial material relocated along a stream by flooding. Most driftwood can contain empty molluscan shells or a minor proportion of live individuals (i.e. molluscan allocoenoses). Drifted material is important for spreading of fauna and flora. Molluscan allocoenoses can provide valuable information on molluscan fauna of the upstream area. The main objective of the study was to describe changes of the species composition, diversity and similarity in molluscan allocoenoses along the model river ecosystem in relation to land use of partial watersheds. In the years 2010–2011, 23 samples of driftwood were taken at 23 sites along the Hron River (Central Slovakia) from the spring to the mouth. Molluscan allocoenoses were composed of 135 species (95 terrestrial and 40 aquatic). The number of species found at particular sites ranged from 29 to 72 with a mean of 48. We confirmed our hypotheses that similarity in molluscan species composition of driftwood from different sampling sites is related to distance between them, the proportion of woodland species is highest in the upper course of the river with highest forest coverage and, finally, the highest total number of species (gamma diversity) in driftwood is in the most heterogeneous (in terms of land use) middle river section. Whereas alpha and gamma diversity were highest in the middle section, beta diversity was lowest. The molluscan assemblages were most variable within the lower section (the highest beta diversity). The studied river with a length of nearly 280 km appeared to be suitable to allow the changes associated with different land use to be reflected in species composition of molluscs. Changes in molluscan community structure documented by repeated driftwood sampling can reveal the changes in land use within the river watershed. Thus, sampling of driftwood can also be used in landscape ecology research.
Although research on environmental gradients is relatively common, the altitudinal gradient is one of the least explored. The discrepancies between earlier studies attributing highest diversity to lowest altitude and more recent studies where this altitudinal pattern is not maintained justify the pertinence of investigating the way diversity gradually changes with altitude. The studied altitudinal gradient is located inside the volcanic cone, on one of volcanic island Azores, and the investigated altitudes were 450, 600 and 800 meters a.s.l. Malaise traps were used to capture insects and Diptera were selected for this study. Application of the Zipt-Mandelbrot model to rank-abundance curves of Diptera sampled at three different altitudes, as well as analyses of richness, diversity and evenness, led to the conclusion that medium altitude was the stratum with the highest niche diversity, the highest specific diversity and the highest predictability. Non-metric multidimensional scaling allowed an excellent separation of the three altitudes sampled, suggesting that habitat characteristics significantly differ with altitude. The study, undertaken in a volcanic island of the Azores, Atlantic Ocean, will have heuristic interest to the scientific community in general and especially to those researchers studying environmental gradients. The results of this research will underpin further work on the insect biodiversity in the Azores Archipelago.
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