Changes in ant species composition and community organisation along grazing gradients in semi-arid rangelands of the Northern Territory.

2000 ◽  
Vol 22 (2) ◽  
pp. 171 ◽  
Author(s):  
B Hoffmann
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Group Analysis ◽  
Grazing Intensity ◽  
Cattle Grazing ◽  
Northern Territory ◽  
Rangeland Management ◽  
Community Organisation ◽  
The Impact ◽  
Semi Arid

The impact of cattle grazing on ant diversity, species composition and community organisation was investigated in the Victoria River District of the Northern Territory, using distance from water as a surrogate of grazing intensity. Two gradients were sampled, one on red earth at Kidman Springs (5 plots), the other on black cracking clay at Mount Sanford (6 plots). Sites were sampled in April (both sites) and October (Kidman Springs only)1998. The two sites supported distinctly different ant communities, with 70 species at Kidman Springs and 36 at Mount Sanford. Species richness and total abundance did not change significantly with distance from water, although species richness was always greatest at the most distant plot. However, multivariate analysis showed that ant species composition changed markedly. Despite large changes in species composition, the abundance of only six of the 24 most common species (two at Kidman Springs and four at Mount Sanford) were significantly correlated with grazing intensity. The abundance of Bassian taxa was promoted by grazing, whereas the species richness of Torresian taxa and the abundance and species richness of Widespread taxa were suppressed. Ant functional group analysis showed community organisation was resilient, with slight changes being primarily driven by Hot Climate Specialists and dependent on the season. However, the relative richness of five functional groups correlated significantly with grazing intensity, all negatively. Ant variables suppressed by grazing were positively associated with patch cover variables and litter, and negatively correlated with annual grass and bare ground, and may serve as indicators of rangeland condition. Key words: biodiversity, cattle grazing, indicators, piosphere, rangeland management, semi-arid, tropical savannas

scholarly journals Native forests but not agroforestry systems preserve arbuscular mycorrhizal fungal species richness in southern Ethiopia

Mycorrhiza ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 749-759
Author(s):  
Zerihun Belay ◽  
Mesele Negash ◽  
Janne Kaseva ◽  
Mauritz Vestberg ◽  
Helena Kahiluoto
Keyword(s):  
Land Use ◽  
Species Richness ◽  
Species Composition ◽  
Arbuscular Mycorrhizal ◽  
Soil Samples ◽  
Southern Ethiopia ◽  
Native Forest ◽  
Native Forests ◽  
Land Use Types ◽  
The Impact

Abstract The rapid conversion of native forests to farmland in Ethiopia, the cradle of biodiversity, threatens the diversity of the arbuscular mycorrhizal fungi (AMF) pivotal to plant nutrition and carbon sequestration. This study aimed to investigate the impact of this land-use change on the AMF species composition and diversity in southern Ethiopia. Soil samples were collected from nine plots in each of three land-use types: native forest, agroforestry, and khat monocropping. The plots of the three land-use types were located adjacent to each other for each of the nine replicates. Three 10 × 10m subplots per plot were sampled. AMF spores were extracted from the soil samples, spore densities were determined, and species composition and diversity were evaluated through morphological analysis. Both spore density and species richness were statistically significantly higher in the native forest than in the agroforestry plots with no clear difference to khat, whereas the true diversity (exponential of Shannon–Wiener diversity index) did not differ among the three land-use types due to high evenness among the species in agroforestry. In total, 37 AMF morphotypes belonging to 12 genera in Glomeromycota were found, dominated by members of the genera Acaulospora and Glomus. The highest isolation frequency index (78%) was recorded for Acaulospora koskei from native forest. Consequently, the agroforestry system did not appear to aid in preserving the AMF species richness of native forests relative to perennial monocropping, such as khat cultivation. In contrast, the native forest areas can serve as in situ genetic reserves of mycorrhizal symbionts adapted to the local vegetative, edaphic, and microbial conditions.

scholarly journals Quantifying the impact of environmental factors on the spatiotemporal structure of insect communities in a semi-arid Sabkha ecosystem

2015 ◽  
Author(s):  
Haroun Chenchouni ◽  
Taha Menasria ◽  
Souad Neffar ◽  
Smail Chafaa ◽  
Liès Bradai ◽  
...  
Keyword(s):  
Species Richness ◽  
Vegetation Cover ◽  
Shannon Index ◽  
Trophic Groups ◽  
Insect Community ◽  
Insect Communities ◽  
Vegetation Parameters ◽  
Two Parameters ◽  
The Impact ◽  
Semi Arid

The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, where Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different site stations and seasons.

Comparison of the diets of sheep and cattle grazing a semi-arid Chenopod shrubland.

1980 ◽  
Vol 2 (1) ◽  
pp. 67 ◽  
Author(s):  
RD Graetz ◽  
AD Wilson
Keyword(s):  
Nitrogen Content ◽  
Cattle Grazing ◽  
Animal Production ◽  
Rangeland Management ◽  
Plant Group ◽  
Exact Relationship ◽  
Semi Arid

Samples of the diets of oesophageally fistulated sheep and cattle grazing a semi-arid chenopod shrubland dominated by bladder saltbush (Atrip!ex ~'esicaria Hew. ex Benth.) were collected over a four year period. Seasonal condiiions varied from very wet to near drought. The diets of the two herbivores were different on all sampling occasions. However, it can be generalized that overall, sheep had a greater grass component in their diets and that cattle in compensation ate more saltbush than did sheep. Both sheep and cattle exhibited considerable diet selectivity and flexibility. Exact relationship between the measure of forage on offer and the proportions of any plant group in the diet could not be determined from the data collected in this experiment. However, hirearchies of preference were established. The differences in digestibility and nitrogen content of the diets between the two herbivores were appreciable with sheep mostly selecting a diet of higher digestibility and nitrogen content. The implications of these data for animal production and rangeland management are discussed.

Potential impacts of fire and grazing in an endangered ecological community: plant composition and shrub and eucalypt regeneration in Cumberland Plain Woodland

2004 ◽  
Vol 52 (1) ◽  
pp. 23 ◽  
Author(s):  
Sarah J. Hill ◽  
Kristine French
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Species Interactions ◽  
Ecological Community ◽  
Plant Composition ◽  
Shrub Species ◽  
Pre Treatment ◽  
Species Richness And Abundance ◽  
The Impact ◽  
Canopy Species

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.

scholarly journals Quantifying the impact of environmental factors on the spatiotemporal structure of insect communities in a semi-arid Sabkha ecosystem

2015 ◽  
Author(s):  
Haroun Chenchouni ◽  
Taha Menasria ◽  
Souad Neffar ◽  
Smail Chafaa ◽  
Liès Bradai ◽  
...  
Keyword(s):  
Species Richness ◽  
Vegetation Cover ◽  
Shannon Index ◽  
Trophic Groups ◽  
Insect Community ◽  
Insect Communities ◽  
Vegetation Parameters ◽  
Two Parameters ◽  
The Impact ◽  
Semi Arid

The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, where Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different site stations and seasons.

scholarly journals Effects of grazing intensity and the use of veterinary medical products on dung beetle biodiversity in the sub-mountainous landscape of Central Italy

2016 ◽  
Author(s):  
Mattia Tonelli ◽  
José R. Verdú ◽  
Mario E. Zunino
Keyword(s):  
Species Richness ◽  
Beta Diversity ◽  
Central Italy ◽  
Grazing Intensity ◽  
Alpha Diversity ◽  
Dung Beetle ◽  
Dung Beetles ◽  
Negative Consequences ◽  
Medical Products ◽  
The Impact

Grazing extensification and intensification are among the main problems affecting European grasslands. We analyze the impact of grazing intensity (low and moderate) and the use of veterinary medical products (VMPs) on the dung beetle community in the province of Pesaro-Urbino (Italy). Grazing intensity is a key factor in explaining the diversity of dung beetles. In the case of the alpha diversity component, sites with a low level of grazing activity – related in a previous step to the subsequent abandonment of traditional farming – is characterized by a loss of species richness (q = 0) and a reduction in alpha diversity at the levels q = 1 and q = 2. In the case of beta diversity, sites with a different grazing intensity show remarkable differences in terms of the composition of their species assemblages. The use of VMPs is another important factor in explaining changes in dung beetle diversity. In sites with a traditional use of VMPs, a significant loss of species richness and biomass is observed, as is a notable effect on beta diversity. In addition, the absence of indicator species in sites with a historical use of VMPs corroborates the hypothesis that these substances have a ubiquitous effect on dung beetles. However, the interaction between grazing activity and VMPs when it comes to explaining changes in dung beetle diversity is less significant (or is not significant) than the main effects (each factor separately) for alpha diversity, biomass and species composition. This may be explained if we consider that both factors affect the various species differently. In other words, the reduction in dung availability affects several larger species more than it does very small species, although this does not imply that the former are more susceptible to injury caused by the ingestion of dung contaminated with VMPs. Finally, in order to prevent negative consequences for dung beetle diversity, we propose the maintenance of a moderate grazing intensity and the rational use of VMPs. It is our view that organic management can prevent excessive extensification while providing an economic stimulus to the sector. Simultaneously, it can also prevent the abuse of VMPs.

scholarly journals Roads affect the spatial structure of butterfly communities in grassland patches

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5413 ◽  
Author(s):  
Piotr Skórka ◽  
Magdalena Lenda ◽  
Dawid Moroń
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Plant Species ◽  
Butterfly Species ◽  
Road Mortality ◽  
Road Verge ◽  
Total Species Richness ◽  
Butterfly Communities ◽  
Road Verges ◽  
The Impact

Roads may have an important negative effect on animal dispersal rate and mortality and thus the functioning of local populations. However, road verges may be surrogate habitats for invertebrates. This creates a conservation dilemma around the impact of roads on invertebrates. Further, the effect of roads on invertebrates is much less understood than that on vertebrates. We studied the effect of roads on butterflies by surveying abundance, species richness and composition, and mortality in ten grassland patches along high-traffic roads (∼50–100 vehicles per hour) and ten reference grassland patches next to unpaved roads with very little traffic (<1 vehicle per day) in southern Poland. Five 200-m transects parallel to the road were established in every grassland patch: at a road verge, 25 m from the verge, in the patch interior, and 25 m from the boundary between the grassland and field and at the grassland-arable field boundary. Moreover, one 200-m transect located on a road was established to collect roadkilled butterflies. The butterfly species richness but not abundance was slightly higher in grassland patches adjacent to roads than in reference grassland patches. Butterfly species composition in grasslands adjacent to roads differed from that in the reference patches. Proximity of a road increased variability in butterfly abundances within grassland patches. Grassland patches bordering roads had higher butterfly abundance and variation in species composition in some parts of the grassland patch than in other parts. These effects were not found in reference grassland patches, where butterfly species and abundance were more homogenously distributed in a patch. Plant species composition did not explain butterfly species. However, variance partitioning revealed that the presence of a road explained the highest proportion of variation in butterfly species composition, followed by plant species richness and abundance in grassland patches. Road mortality was low, and the number of roadkilled butterflies was less than 5% of that of all live butterflies. Nevertheless, the number and species composition of roadkilled butterflies were well explained by the butterfly communities living in road verges but not by total butterfly community structure in grassland patches. This study is the first to show that butterfly assemblages are altered by roads. These results indicate that: (1) grassland patches located near roads are at least as good habitats for butterflies as reference grassland patches are, (2) roads create a gradient of local environmental conditions that increases variation in the abundance of certain species and perhaps increases total species richness in grassland patches located along roads, and (3) the impact of roads on butterflies is at least partially independent of the effect of plants on butterflies. Furthermore, (4) the direct impact of road mortality is probably spatially limited to butterflies living in close proximity to roads.

scholarly journals Ephemeroptera (Mayflies) Assemblages and Environmental Variation along Three Streams Located in the Dry-Hot Valleys of Baima Snow Mountain, Yunnan, Southwest China

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 775
Author(s):  
Muhammad Farooq ◽  
Xianfu Li ◽  
Lu Tan ◽  
Davide Fornacca ◽  
Yanpeng Li ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Community Composition ◽  
Environmental Variation ◽  
Diversity Indices ◽  
Freshwater Ecosystems ◽  
Environmental Data ◽  
Elevation Gradients ◽  
Depth Analysis ◽  
The Impact

Mountain freshwater ecosystems are threatened all over the world by a range of human-induced stresses, ensuing in a rapid loss of habitats and species diversity. Many macroinvertebrates are reactive to habitat disturbance, and mayflies (Ephemeroptera) are amongst the most sensitive groups. Despite they are susceptible to environmental deviation, knowledge concerning their species richness and diversity is still unknown in remote areas. The objectives of this study were to (1) investigate the mayfly species assemblage and community composition along different mountain streams and assess potential differences, and (2) identify the environmental variation and its influence on the structure of mayfly communities within such freshwater systems. We collected biological and environmental data from 35 sites situated along elevation gradients in the Baima Snow Mountain, northwest Yunnan, China. Multivariate analyses were performed on the environmental variables and the mayfly species composition, as well as on richness and diversity indices. We found that the community composition of mayflies was different across all three watercourses. Among the 18 Ephemeroptera taxa identified, Baetis sp. and Baetiella marginata were highly dominant, accounting for over 50% of the dissimilarity of each stream. In terms of species assemblages, almost all sites in the Yeri stream hosted good-quality habitats for several mayfly species, as reflected by the highest species richness. The Benzilan stream followed, whereas the Sharong stream showed relatively low mayfly assemblage. This variation was explained by the high environmental heterogeneity between the three watercourses. In particular, the RDA model revealed that among the different environmental factors analyzed, altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition. Moreover, the altitude alone explained 17.74% of the variation, and in-depth analysis confirmed its significant effect on diversity indices. Further research should focus on evaluating the scale of threats to this important group of insects in the mountain freshwater ecosystem, particularly the impact of human-induced disturbances such as land use/landcover alterations.

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