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Altitudinal gradients in a volcanic island: effect on biodiversity and species richness of the dipteran fauna

100%

Ferreira T. , Ribeiro E. , Duarte-Rodrigues P. , Boavida M.-J.

Polish Journal of Ecology

2012

tom 60

nr 3

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.

Avian responses to undergrowth removal in a suburban wood

80%

Orlowski G. , Martini K. , Martini M.

Polish Journal of Ecology

2008

tom 56

nr 3

487-495

The breeding (in 1991–1996) and wintering (1991/1992–1993/1994) avian community were surveyed in a suburban wood (29.27 ha) in Wrocław city (SW Poland). The 1992 breeding season began together with a drastic clearance of the compact undergrowth with the use of heavy machinery. A slump of abundance of the species nesting on the ground and small shrubs (≤1.5 m) followed, coupled with some modifications to their breeding behaviour, such as clustering of several singing males on the remaining bushes (Blackcap Sylvia atricapilla L.) and nesting in the piles of cut branches (Blackbird Turdus merula L.). As a result of the removal of 52% of the whole undergrowth the density of species nesting on the ground and small shrubs in 1992 was by 26% lower than in 1991 (decrease from 61.8 to 46.3 pairs 10 ha⁻¹). After 1993 a spontaneous regeneration of the bushy vegetation took place, with the ground and shrub-nesting species’ density recovering to 49.4 pairs 10 ha⁻¹ in 1996. After 1991 the park was colonized by 9 new hole-nester species, which was accompanied by the increase of density of this group (from 21.9 in 1991 to 37.9 pairs 10 ha⁻¹ in 1996). Throughout the entire study period a slight rise of density of birds nesting in tree canopies was visible (21.3 pairs 10 ha⁻¹ in 1991 and 33.8 pairs 10 ha⁻¹ in 1996). A year after the shrub clearance the wintering bird abundance was significantly lower (half of the previous numbers), with plant-eaters and insectivores hardest hit, especially Great Tit Parus major L. (average number of inidividuals per one count amounted to 59.2 in 1991/1992 and 21.9 in 1992/1993) and Blue Tit Parus caeruleus L. (respectively 37.0 and 16.0 ind.). An adequate timetable of vegetation clearance must be set up in the course of any decision-making process regarding green areas management to ensure the environmental issues are addressed properly

Comparison of the impacts of climate change and anthropogenic disturbances on the El Arish coast and seaweed vegetation after ten years in 2010, North Sinai, Egypt

70%

El Shoubaky G. A.

Oceanologia

2013

tom 55

nr 3