Changes in trophic abundance of soil arthropods along a grass-shrub-forest gradient

Ecological theory suggests that along productivity gradients, abundances of organisms within trophic levels will increase in a stepwise pattern from producers to consumers. To test this theory I investigated changes in abundance of soil arthropods at three trophic levels: microphytophages, represented by Collembola, predacious mites (Acari) that feed on Collembola, and three groups of macroarthropods (spiders, ants, and centipedes) that were observed to feed on mites. Changes in abundance were monitored along a gradient in vegetation structure from grass to shrub to forest in the Canadian prairies. I controlled for temporal variation in abundance among years and surveys within a year. As predicted, (i) numbers of Collembola did not change with increases in productivity; (ii) mite numbers were greatest in the shrublands; and (iii) numbers of macroarthropod predators increased from grassland to shrubland, and there was a nonsignificant increase in numbers of spiders and centipedes in forest habitat. Contrary to predictions, macroarthropod numbers were not significantly greater in forest habitat, and ant numbers actually declined. Possible explanations for the lack of increase in macroarthropod predator abundance in the forest habitat with the greatest productivity include decreased ground-level humidity and greater abundance of macroarthropod predators and parasites in forest environments.

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Capercaillie breeding success in relation to forest habitat and predator abundance

Journal of Applied Ecology ◽

10.1111/j.1365-2664.2004.00875.x ◽

2004 ◽

Vol 41 (1) ◽

pp. 59-71 ◽

Cited By ~ 64

Author(s):

D. Baines ◽

R. Moss ◽

D. Dugan

Keyword(s):

Breeding Success ◽

Forest Habitat ◽

Predator Abundance

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Anticipated or delayed responses to rainfall: Effects of rainfall on arthropods assemblage in an enclave of evergreen forest

Research Society and Development ◽

10.33448/rsd-v9i12.10923 ◽

2020 ◽

Vol 9 (12) ◽

pp. e47291210923

Author(s):

Raul Azevedo ◽

Raimundo Nonato Costa Ferreira ◽

Francisco Roberto de Azevedo ◽

Larissa da Silva Nascimento ◽

João Roberto Pereira dos Santos ◽

...

Keyword(s):

Species Richness ◽

Evergreen Forest ◽

Annual Rainfall ◽

Delayed Response ◽

Soil Arthropods ◽

Seasonally Dry ◽

Caatinga Vegetation ◽

Fauna Composition ◽

Predator Abundance ◽

Arthropod Abundance

In northeast Brazil, the most part of vegetation is a deciduous seasonally dry tropical forest called of “Caatinga”. Despite the semi-arid areas correspond to most of the caatinga vegetation, there are some areas 500 m above sea level with an annual rainfall up to 1200 mm forming evergreen forest enclaves. Macroarthropod abundance and fauna composition differences in Caatinga are related to seasonal rainfall effects but, this difference is unclear in the enclaves of evergreen forests. Thus, the aim of this study was to measure the effects of rainfall on insect, arachnid, and centipede assemblages in an enclave of evergreen forest within the Caatinga vegetation. We tested the following hypotheses: 1) rainfall changes arthropod abundance and species richness; 2) predator abundance correlate with prey, and 3) abundance arthropod abundance and species richness exhibit a delayed or anticipated response to rainfall. No effects of rainfall on insects and arachnids abudance were observed. There was a significant correlation between prey and predator abundance with changes in dominant species between the rainy and dry seasons. The insects and arachnids can show some anticipated responses to rainfall. The abundance and richness of centipedes were influenced by rainfall whith a delayed response. Our findings indicate that, in evergreen forest enclaves within Caatinga vegetation, the soil arthropods show different responses compared to rainfall than the most common areas of the Caatinga domain and an increase in the detection of insects and arachnids just before the beginning of the rainy season.

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Trophic guilds of generalist feeders in soil animal communities as indicated by stable isotope analysis (15N/14N)

Bulletin of Entomological Research ◽

10.1017/s0007485309990587 ◽

2010 ◽

Vol 100 (5) ◽

pp. 511-520 ◽

Cited By ~ 22

Author(s):

K. Oelbermann ◽

S. Scheu

Keyword(s):

Stable Isotope ◽

Food Webs ◽

Trophic Level ◽

A Priori ◽

Isotope Analysis ◽

Trophic Levels ◽

Soil Arthropods ◽

Trophic Guilds ◽

Natural Variations ◽

Animal Communities

AbstractWe investigated if the commonly used aggregation of organisms into trophic guilds, such as detritivores and predators, in fact represent distinct trophic levels. Soil arthropods of a forest-meadow transect were ascribed a priori to trophic guilds (herbivores, detritivores, predators and necrovores), which are often used as an equivalent to trophic levels. We analysed natural variations in 15N/14N ratios of the animals in order to investigate the trophic similarity of organisms within (a priori defined) trophic guilds. Using trophic guilds as an equivalent to trophic level, the assumed stepwise enrichment of 15N by 3.4‰ per trophic level did not apply to detritivores; they were only enriched in 15N by on average 1.5‰ compared to litter materials. Predators on average were enriched in 15N by 3.5‰ compared to detritivores. Within detritvores and predators δ15N signatures varied markedly, indicating that these trophic guilds are dominated by generalist feeders which form a gradient of organisms feeding on different resources. The results indicate that commonly used trophic guilds, in particular detritivores and predators, do not represent trophic levels but consist of subguilds, i.e. subsets of organisms differing in resource utilization. In particular, in soil and litter food webs where trophic level omnivory is common, the use of distinct trophic levels may be inappropriate. Guilds of species delineated by natural variations of stable isotope ratios are assumed to more adequately represent the structure of litter and soil food webs allowing a more detailed understanding of their functioning.

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Abundance and diversity of soil arthropods in a tropical deciduous forest and mangrove forest of Kerala, India

ENTOMON ◽

10.33307/entomon.v45i1.505 ◽

2020 ◽

Vol 45 (1) ◽

pp. 69-74

Author(s):

Krishnapriya P D ◽

Binoy C F

Keyword(s):

Deciduous Forest ◽

Monsoon Season ◽

Winter Season ◽

Similarity Index ◽

Tropical Deciduous Forest ◽

Soil Arthropods ◽

Mangrove Habitat ◽

Forest Habitat ◽

Different Types ◽

Abundance And Diversity

The abundance and diversity of soil arthropods in the Marottichal tropical deciduous forest and Kodungallur mangrove habitat of Thrissur District were studied. A total of 98 species belonging to 15 orders and 5 classes were obtained from the study area. Of these, 59 species belonging to 13 orders and 3 classes were recorded from forest habitat and 47 species belonging to 8 orders and 4 classes from mangroves. Order Coleoptera was the most abundant in both forest (30.69%) and mangrove (36.5%) habitats. Sorenson’s similarity index showed only 15.09% similarity among species indicating that both the habitats harboured significantly different types of species. It was noted that, as the humidity and moisture decreased, the abundance of species also decreased in both habitats. Temperature was negatively correlated with abundance of species. The diversity in forest habitat (4.03) was higher than mangrove habitat (3.77). Maximum abundance was recorded during monsoon season (June- August) and least during winter season (December- February). The species accumulation curve plotted for the study area indicated that there are more species likely to be discovered in both the habitats.

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Are the vegetation structure and composition of the shrubby Caatinga free from edge influence?

Acta Botanica Brasilica ◽

10.1590/s0102-33062008000400018 ◽

2008 ◽

Vol 22 (4) ◽

pp. 1077-1084 ◽

Cited By ~ 17

Author(s):

André Maurício de Melo Santos ◽

Bráulio Almeida Santos

Keyword(s):

Vegetation Structure ◽

Forest Ecosystems ◽

A Priori ◽

Principal Component ◽

Ground Level ◽

Stem Density ◽

Floristic Similarity ◽

Physical Conditions ◽

Ecological Importance ◽

Edge Influence

Edge influence, or edge effect, drives many biological changes in fragmented landscapes. This has been extensively studied in many forest ecosystems, but it remains to be described for the Brazilian Caatinga. Based on the biotic and physical conditions of the shrubby Caatinga, our prediction a priori was that this type of vegetation is free from edge influence in terms of vegetation structure and composition. We sampled shrubs, cacti and trees in twenty 200 m² plots on old edges (>60 yrs old) and interior of a 690 ha fragment, partially isolated and surrounded by Opuntia ficus-indica cacti. Plant height, stem diameter at ground level, stem density, species richness and diversity were statistically equal between edge and interior habitats. Magnitude of edge influence varied from -0.027 to 0.027, indicating low ecological importance of edge creation for the measured variables. Additionally, floristic similarity between habitats was 90% and a principal component analysis showed that species composition varied in a similar manner at edges and interiors. These results indicate that the vegetation of the sampled fragment is not ecologically affected by the creation of edges and suggests that changes in physical conditions and resource availability after edge creation are not enough to eliminate established plants or to alter recruitment and survival of new individuals.

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The ecology of Paleozoic terrestrial arthropods: the fossil evidence

Canadian Journal of Zoology ◽

10.1139/z90-262 ◽

1990 ◽

Vol 68 (9) ◽

pp. 1807-1834 ◽

Cited By ~ 145

Author(s):

William A. Shear ◽

Jarmila Kukalová-Peck

Keyword(s):

Primary Productivity ◽

Terrestrial Ecosystems ◽

Ground Level ◽

Original Data ◽

Trophic Levels ◽

Early Paleozoic ◽

Selective Force ◽

Terrestrial Arthropods ◽

Fossil Evidence ◽

Web Building

The available fossil evidence for the ecology of terrestrial arthropods in the Paleozoic is reviewed and reinterpreted. Some original data are provided, derived mainly from the detailed morphology of mouthparts, genitalia, cuticular vestiture, and body form. Paleozoic chelicerates were more diverse than their modern descendants and were probably dominant ground-level and arboreal predators. Web-building spiders and highly diversified mites appear to have been absent. Paleozoic myriapods include possibly the earliest land animals, and as abundant detritivores, provided a major conduit for primary productivity into higher trophic levels. Paleozoic insects present many difficulties of interpretation, but appear to have been extraordinarily diverse and may have played quite different ecological roles from today's insects, viewed as a whole. It is postulated that herbivory, defined as predation on living plants, may have been rare in early Paleozoic terrestrial ecosystems, and that most primary productivity was funneled through detritivores and decomposers. In the late Paleozoic, the evidence for herbivory by insects, except for feeding on fructifications, is rare. Insects seem to have played a major part as a selective force on plant fructifications.

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Deer Exclusion Changes Vegetation Structure and Hunting Guilds of Spiders, but Not Multitrophic Understory Biodiversity

Diversity ◽

10.3390/d13010025 ◽

2021 ◽

Vol 13 (1) ◽

pp. 25

Author(s):

Roman Bucher ◽

Jonas Rochlitz ◽

Nathalie Wegner ◽

Anna Heiß ◽

Alexander Grebe ◽

...

Keyword(s):

Plant Communities ◽

Vegetation Structure ◽

Structural Changes ◽

Forest Ecosystems ◽

Trophic Levels ◽

Cascading Effects ◽

Vegetation Height ◽

Spider Communities ◽

The Impact ◽

Predatory Arthropods

Ungulate herbivores modify plant community compositions, which can modulate biodiversity at higher trophic levels. However, these cascading effects on herbivorous and predatory arthropods in forest ecosystems remain poorly understood. We compared plant and arthropod communities between fenced exclosures and unfenced control plots in a permanent forest in Germany. After five years of deer exclusion, we quantified plant diversity and vegetation structure as well as the diversity of insects and spiders in 32 pair-wise plots. In addition, we compared spider communities with respect to different hunting guilds because they are expected to have different requirements for vegetation structure. Although we did not find differences in plant communities, vegetation height and heterogeneity were higher in exclosures compared to control plots. The diversity of insects and spiders was not affected by deer presence. However, the abundance of sheet-web weavers and ambush hunters was lower in exclosures whereas ground hunters were more common in exclosure plots. Structural changes in the vegetation changed predator hunting guilds even though mere abundance and biodiversity indices were not affected. We therefore suggest that monitoring of vegetation structure and associated functional groups seems more sensitive to assess the impact of ungulate herbivores compared to taxonomic metrics.

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Effects of Vibration on the Preparation of Ultrathin Sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007223x ◽

1973 ◽

Vol 31 ◽

pp. 358-359

Author(s):

Joseph M. Blum ◽

Edward P. Gargiulo ◽

J. R. Sawers

Keyword(s):

Cutting Speed ◽

Ground Level ◽

Environmental Vibration ◽

Block Face ◽

Ultrathin Sections ◽

Embedding Medium ◽

Thickness Variations ◽

Building Walls ◽

Cutting Direction ◽

Diamond Knife

It is now well-known that chatter (Figure 1) is caused by vibration between the microtome arm and the diamond knife. It is usually observed as a cyclical variation in “optical” density of an electron micrograph due to sample thickness variations perpendicular to the cutting direction. This vibration might be induced by using too large a block face, too large a clearance angle, excessive cutting speed, non-uniform embedding medium or microtome vibration. Another prominent cause is environmental vibration caused by inadequate building construction. Microtomes should be installed on firm, solid floors. The best floors are thick, ground-level concrete pads poured over a sand bed and isolated from the building walls. Even when these precautions are followed, we recommend an additional isolation pad placed on the top of a sturdy table.

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