Crop tree release increased the density of soil nematodes and improved the food web structure

As a special thinning method, crop tree release (CTR) has a beneficial effect on forest environments and structures by changing forest light, heat, and water. However, the impact of CTR on underground biodiversity remains unclear. Therefore, we analyzed the composition, diversity, and metabolic footprints of soil nematode communities under three CTR (100, 150, and 200 trees·ha–1) treatments, as well as a no CTR treatment, in Pinus massoniana Lamb. plantations. The results showed that CTR increased the density of soil nematodes (P < 0.05), the number of omnivore–predator nematodes (P < 0.05), and the diversity (H′) of nematodes (P < 0.05) and enriched the food web structure of soil nematodes. In the medium CTR density treatment (150 trees·ha–1), the nematode density and diversity (H′) were the highest (P < 0.05), the number of omnivore–predator nematodes was also the highest (P < 0.05), and the enrichment index and structure index values of the soil nematodes reached the maximum at the depth of 0–10 cm (P < 0.05). Our results indicated that the community structure of soil nematodes became more stable and mature after CTR, which may be attributed to the changes of soil condition, especially soil organic matter, and plant diversity indirectly.

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The impact of intraspecific variation on food web structure

Ecology ◽

10.1002/ecy.2523 ◽

2018 ◽

Vol 99 (12) ◽

pp. 2712-2720 ◽

Cited By ~ 9

Author(s):

Tom Clegg ◽

Mohammad Ali ◽

Andrew P. Beckerman

Keyword(s):

Food Web ◽

Intraspecific Variation ◽

Food Web Structure ◽

Web Structure ◽

The Impact

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Untangling the roles of parasites in food webs with generative network models

10.1101/019497 ◽

2015 ◽

Cited By ~ 1

Author(s):

Abigail Z. Jacobs ◽

Jennifer A. Dunne ◽

Cristopher Moore ◽

Aaron Clauset

Keyword(s):

Food Web ◽

Food Webs ◽

Statistical Physics ◽

Network Models ◽

Food Web Structure ◽

Free Living ◽

Web Structure ◽

Living Species ◽

Parasitic Interactions ◽

The Impact

Food webs represent the set of consumer-resource interactions among a set of species that co-occur in a habitat, but most food web studies have omitted parasites and their interactions. Recent studies have provided conflicting evidence on whether including parasites changes food web structure, with some suggesting that parasitic interactions are structurally distinct from those among free-living species while others claim the opposite. Here, we describe a principled method for understanding food web structure that combines an efficient optimization algorithm from statistical physics called parallel tempering with a probabilistic generalization of the empirically well-supported food web niche model. This generative model approach allows us to rigorously estimate the degree to which interactions that involve parasites are statistically distinguishable from interactions among free-living species, whether parasite niches behave similarly to free-living niches, and the degree to which existing hypotheses about food web structure are naturally recovered. We apply this method to the well-studied Flensburg Fjord food web and show that while predation on parasites, concomitant predation of parasites, and parasitic intraguild trophic interactions are largely indistinguishable from free-living predation interactions, parasite-host interactions are different. These results provide a powerful new tool for evaluating the impact of classes of species and interactions on food web structure to shed new light on the roles of parasites in food webs.

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Seasonal Stabilities of Soil Nematode Communities and Their Relationships with Environmental Factors in Different Temperate Forest Types on the Chinese Loess Plateau

Forests ◽

10.3390/f12020246 ◽

2021 ◽

Vol 12 (2) ◽

pp. 246

Author(s):

Na Huo ◽

Shiwei Zhao ◽

Jinghua Huang ◽

Dezhou Geng ◽

Nan Wang ◽

...

Keyword(s):

Food Web ◽

Loess Plateau ◽

Soil Nematode ◽

Soil Food Web ◽

Food Web Structure ◽

Nematode Communities ◽

Web Structure ◽

Soil Nematode Community ◽

Nematode Abundance ◽

Soil Nematode Communities

The bottom-up effects of vegetation have been documented to be strong drivers of the soil food web structure and functioning in temperate forests. However, how the forest type affects the stability of the soil food web is not well known. In the Ziwuling forest region of the Loess Plateau, we selected three typical forests, Pinus tabuliformis Carrière (PT), Betula platyphylla Sukaczev (BP), and Quercus liaotungensis Koidz. (QL), to investigate the soil nematode community characteristics in the dry (April) and rainy (August) season, and analyzed their relationships with the soil properties. The results showed that the characteristics of the soil nematode communities and their seasonal variations differed markedly among the forest types. Compared to P. tabuliformis (PT), the B. platyphylla (BP) and Q. liaotungensis (QL) forests had higher plant diversity and more easily decomposed litters, which were more effective for improving the soil resource availability, thus, leading to more beneficial effects on the soil nematode community. In both the dry and rainy season, the soil nematode abundance was the highest in the BP forest. The Shannon–Wiener diversity index (H’), Pielou’s evenness index (J’), and nematode channel ratio index (NCR) were higher, while the Simpson dominance index (λ) and plant parasite index (PPI) were lower, in the BP and QL forests compared with in the PT forest. From the dry to rainy season, the total nematode abundance and the abundance of fungivores, bacterivores, and omnivore-predators, significantly increased in the QL and PT forests, and the values of the Wasilewska index (WI), maturity index (MI), H’, J’, λ, and NCR showed the most significant seasonal variability in the PT forest, which were mainly driven by changes in the soil labile C and N and the moisture content between the two seasons. Generally, the seasonal stability of the soil nematode communities was the highest in the BP forest and the poorest in the PT forest, probably due to variations in the plant diversity. Our results suggest the importance of tree species and diversity as bottom-up regulating factors of the soil food web structure, function, and seasonal stability, which has important implications for sustainable forest management in the Loess Plateau and other temperate regions.

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Concomitant predation on parasites -- removal of trematode-infected snails by predacious fish in a subarctic lake

10.22541/au.163350966.66754241/v1 ◽

2021 ◽

Author(s):

Miroslava Soldanova ◽

David Thieltges ◽

Jessica Schwelm ◽

Tereza Vyhlídalová ◽

Gabrielle van Beest ◽

...

Keyword(s):

Biological Control ◽

Food Web ◽

Salmo Trutta ◽

Prey Availability ◽

Arctic Charr ◽

Food Web Structure ◽

Free Living ◽

Web Structure ◽

Subarctic Lake ◽

The Impact

Concomitant predation, which occurs when parasites are consumed and digested along with their hosts, has previously been suggested as a profound factor determining food web structure. Few studies have adressed the impact of concomitant predation in research on behaviourally parasite-modified prey or in biological control studies. However, empirical evidence of concomitant predation effects on hosts infected with multiple parasite taxa is lacking. We investigated the importance of concomitant predation on digenean trematodes by examining the degree of snail (Radix balthica, first intermediate host) seasonal predation by Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) by contrasting infection rates of free-living snails obtained from a lake vs predated snails retrieved from fish stomachs and intestines. The fish consumed infected snails nearly at all seasons, demonstrating that concomitant predation in the model subarctic lake is common, likely indirectly affecting trematode transmission by reducing host and parasite populations. The overall trematode prevalence in both snail groups was season-independent, being however substantially higher in free-living compared to predated snails. The net effects of underlying mechanisms related to prey availability, fish feeding ecology, continuous presence of dominant trematodes and, most importantly, size of fish and snails drove the strength of predator-prey interactions and infection patterns in both snail groups. Larger fish preying upon larger snails, which simultaneously harboured more infections, may induce a substiantial negative effect of concomitant predation on snail and parasite population dynamics, with serious implications for food web structure and ecosystem functioning. This study contributes to a better understanding of the role of non-host predators in regulating trematode infection, community structure and transmisison patterns, biomass transfer and energy flow in food webs. Our findings also highlight the importance of studying the impact and extent of concomitant predation in terms of parasite seasonal dynamics and biological control of infectious diseases.

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Cladocera paleocommunity to disentangle the impact of anthropogenic and climatic stressors on a deep subalpine lake ecosystem (Lake Iseo, Italy)

Aquatic Ecology ◽

10.1007/s10452-021-09850-9 ◽

2021 ◽

Author(s):

Barbara Leoni ◽

Martina Patelli ◽

Veronica Nava ◽

Monica Tolotti

Keyword(s):

Species Composition ◽

Food Web ◽

Anthropogenic Pressure ◽

Food Web Structure ◽

Subfossil Cladocera ◽

Web Structure ◽

Pelagic Food Web ◽

The Impact ◽

Plankton Communities

AbstractIn big lakes with strong anthropogenic pressure, it is usually difficult to disentangle the impacts of climate variability from those driven by eutrophication. The present work aimed at the reconstruction of change in the species distribution and density of subfossil Cladocera in Lake Iseo (Italy) in relation to climate and anthropogenic pressure. We related subfossil Cladocera species composition and density in an 80-cm sediment core collected in the pelagic zone of Lake Iseo to long-term temperature trends and phosphorus concentration inferred by diatoms frustules. The Cladocera remains detected in Lake Iseo sediment reflected the species composition and density of modern pelagic Cladocera assemblages. Cladocera rapidly respond to environmental change, and that climate change combined with eutrophication can induce changes in community composition and species density. At the beginning of twentieth century, when global warming was not yet so accentuated, the nutrient increase in water resulted as the principal driver in determining the long-term development of plankton communities and pelagic food web structure. Moreover, catchment-related processes may decisively affect both species composition and density of the lake planktonic communities due to the decrease of lake water transparency induced by input of inorganic material from the catchment area to the lake. The paleolimnological investigation, through the combined study of biotic and abiotic factor, allowed clarifying the synergic effects of the most important drivers of change in lake ecosystems, suggesting that climatic factors should be considered with nutrient availability as determinant element in controlling the temporal development of plankton communities and pelagic food web structure.

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The impact of nonlinear functional responses on the long-term evolution of food web structure

Journal of Theoretical Biology ◽

10.1016/j.jtbi.2004.04.033 ◽

2004 ◽

Vol 229 (4) ◽

pp. 539-548 ◽

Cited By ~ 91

Author(s):

Barbara Drossel ◽

Alan J McKane ◽

Christopher Quince

Keyword(s):

Food Web ◽

Long Term Evolution ◽

Functional Responses ◽

Food Web Structure ◽

Nonlinear Functional ◽

Web Structure ◽

Term Evolution ◽

The Impact

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Impact of fertilization and stocking on trophic interactions and growth of juvenile sockeye salmon (Oncorhynchus nerka)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f02-111 ◽

2002 ◽

Vol 59 (8) ◽

pp. 1361-1373 ◽

Cited By ~ 21

Author(s):

Asit Mazumder ◽

Jim A Edmundson

Keyword(s):

Food Web ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Trophic Levels ◽

Food Web Structure ◽

Web Structure ◽

Mean Size ◽

Average Size ◽

The Impact

Using 16 years of data on nutrients, plankton, and sockeye fry and smolts from Packers Lake, Alaska, we test the impact of nutrients and fry stocking on the growth and productivity of juvenile sockeye salmon (Oncorhynchus nerka). To enhance sockeye production, this lake was fertilized (19831996) and stocked annually (19871996) with sockeye fry. Before fertilization, the density of sockeye fry was low (<0.20 fry·m2), the size and biomass of Daphnia were low, and sockeye smolts were relatively small. Before stocking, all trophic levels responded positively to fertilization. The biomass and mean size of Daphnia increased significantly. The average size of age-1 and age-2 smolts increased three- to four-fold. Fry stocking produced dramatic declines in both biomass and mean length of Daphnia and in size of smolts. When large-sized (>1 mm) Daphnia were significantly reduced in density under heavy predation by sockeye fry, the growth of juvenile sockeye declined, even under continued fertilization. We show that fry density and associated food web structure are major determinants of juvenile sockeye responses to fertilization and stocking. This study probably provides the first long-term experimental results linking limnological and nutrient food web concepts to trophodynamics and productivity of juvenile sockeye salmon.

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