Patterns of shrub species richness and abundance in relation to environmental factors on the Alxa Plateau: Prerequisites for conserving shrub diversity in extreme arid desert regions

Exclosure plots were used to determine the effect of fire and grazing on the structure of a grassy-woodland community. Eighteen months after fire and fence treatments were applied, the species richness, cover and composition of shrubs, trees, herbs and grasses were assessed and compared to pre-treatment censuses. Unburned plots had fewer shrub species and a lower abundance of shrubs, indicating the importance of fire in promoting regeneration of shrub species. Eucalypt species were more abundant and richer following the wildfire burn in summer, suggesting timing of fires is an important aspect in the establishment of the canopy species. Interactions between fire and grazing were found for the abundance of eucalypts (although weak) and resprouting eucalypts, suggesting a subtle interaction between fire and grazing shortly after fire. There was no effect of grazing and no interaction effect between fire and grazing on shrub species richness and abundance or tree species richness and seedling abundance.All plots showed a change in species composition despite treatment, and 46 species (32% of total richness) were recorded only in the final survey. The high rainfall during the 18-month study is likely to be an important factor in facilitating the establishment of species following all disturbances. This may have ameliorated the impact of grazing as abundant food was available throughout the woodland. The interaction between fire and grazing may be more important in structuring these grassy communities during periods of lower rainfall.

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Stream Salamander Species Richness and Abundance in Relation to Environmental Factors in Shenandoah National Park, Virginia

The American Midland Naturalist ◽

10.1674/0003-0031(2005)153[0348:sssraa]2.0.co;2 ◽

2005 ◽

Vol 153 (2) ◽

pp. 348-356 ◽

Cited By ~ 7

Author(s):

EVAN H. CAMPBELL GRANT ◽

ROBIN E. JUNG ◽

KAREN C. RICE

Keyword(s):

Species Richness ◽

Environmental Factors ◽

National Park ◽

Shenandoah National Park ◽

Species Richness And Abundance ◽

Salamander Species

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Effects of size, shape, and edge on vegetation in remnants of the upland boreal mixed-wood forest in agro-environments of Alberta, Canada

Canadian Journal of Botany ◽

10.1139/b07-018 ◽

2007 ◽

Vol 85 (3) ◽

pp. 273-284 ◽

Cited By ~ 14

Author(s):

L. Dennis Gignac ◽

Mark R.T. Dale

Keyword(s):

Species Richness ◽

Alien Species ◽

Plant Species ◽

Fragment Size ◽

Vascular Plant ◽

Plant Species Richness ◽

Percent Cover ◽

Shrub Species ◽

Alien Plant ◽

Species Richness And Abundance

Forty-one remnants of the aspen-dominated upland forest in three subregions of the dry boreal mixed-wood in Alberta were studied to determine effects of fragment size and shape on native and alien plant species richness and abundance in agro-environments. The percent cover of all vascular plant species was visually estimated in 5 m diameter circular plots along transects that covered the length and the width of each fragment. A subset of 12 of the largest fragments (>900 m2) that had distinct interiors (portions of the fragment >15 m from any edge) was used to measure edge effects on the vegetation. Regression analyses revealed significant positive relationships between species richness and area regardless of the subregion. Species richness stabilized in fragments that were larger than 11 ha. Edges did not affect shrub species richness and only affected herbaceous species richness on west- and south-facing aspects. Shrub abundance decreased and herb abundance increased up to 20 m from the edges regardless of orientation. Edges did not support a different suite of species than interiors, although several species occurred more frequently in the interior than along the edges. Alien species richness and abundance reached their highest values between 5 and 15 m from the edge, and some of those species could be found up to 40 m from the edge. Although larger fragments generally supported more alien species than smaller fragments, the smallest fragments had the greatest number of species per metre squared. Results from this study indicated that it would be preferable to conserve larger woodlots rather then several smaller woodlots on the landscape.

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Transformation of upland meadow’s biogeocenosis during processes of overgrowth by the gray alder (Alnus inсаnа (L.) Moench)

Biological Communications ◽

10.21638/spbu03.2016.101 ◽

2016 ◽

Author(s):

Tatiana Guzova ◽

Marina Tikhodeyeva

Keyword(s):

Species Richness ◽

Environmental Factors ◽

Vegetation Type ◽

Habitat Characteristics ◽

Soil Horizons ◽

Herbaceous Vegetation ◽

Indigenous Tree Species ◽

Area Unit ◽

Species Richness And Abundance ◽

Vegetation Species

The article presents results of a study of the environmental conditions transformation during the formation of new phytocenoses by the grey alder. Processes of overgrowing meadows by alder entail a change of habitat characteristics, in particular, reduction of brightness and temperature, a significant increase in litter thickness. In addition, abundance and biomass of earthworms per area unit is reduced in upper soil horizons under the alders, compared to the meadow. Conversion of environmental factors significantly affects the development of herbaceous vegetation: species richness and abundance (cover) of herbaceous vegetation plummets under the influence of alder, as well as floristic heterogeneity of the cover. Undergrowth of spruce — indigenous tree species does not develop in the 60-year-old alder. Overgrowing meadows through the gray alder (compared with aspen and birch) inhibits the passage of autogenous succession, aimed at establishing indigenous vegetation type — spruce. Refs 29. Figs 5. Tables 3.

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