scholarly journals Microbial food web dynamics along a soil chronosequence of a glacier forefield

2011 ◽  
Vol 8 (11) ◽  
pp. 3283-3294 ◽  
Author(s):  
J. Esperschütz ◽  
A. Pérez-de-Mora ◽  
K. Schreiner ◽  
G. Welzl ◽  
F. Buegger ◽  
...  
Keyword(s):  
Food Web ◽  
Microbial Communities ◽  
Food Webs ◽  
Litter Decomposition ◽  
Developmental Stages ◽  
Food Web Dynamics ◽  
Glacier Forefield ◽  
Microbial Food Webs ◽  
And Function ◽  
The 19Th Century

Abstract. Microbial food webs are critical for efficient nutrient turnover providing the basis for functional and stable ecosystems. However, the successional development of such microbial food webs and their role in "young" ecosystems is unclear. Due to a continuous glacier retreat since the middle of the 19th century, glacier forefields have expanded offering an excellent opportunity to study food web dynamics in soils at different developmental stages. In the present study, litter degradation and the corresponding C fluxes into microbial communities were investigated along the forefield of the Damma glacier (Switzerland). 13C-enriched litter of the pioneering plant Leucanthemopsis alpina (L.) Heywood was incorporated into the soil at sites that have been free from ice for approximately 10, 60, 100 and more than 700 years. The structure and function of microbial communities were identified by 13C analysis of phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL). Results showed increasing microbial diversity and biomass, and enhanced proliferation of bacterial groups as ecosystem development progressed. Initially, litter decomposition proceeded faster at the more developed sites, but at the end of the experiment loss of litter mass was similar at all sites, once the more easily-degradable litter fraction was processed. As a result incorporation of 13C into microbial biomass was more evident during the first weeks of litter decomposition. 13C enrichments of both PLEL and PLFA biomarkers following litter incorporation were observed at all sites, suggesting similar microbial foodwebs at all stages of soil development. Nonetheless, the contribution of bacteria, especially actinomycetes to litter turnover became more pronounced as soil age increased in detriment of archaea, fungi and protozoa, more prominent in recently deglaciated terrain.

scholarly journals Microbial food web dynamics along a soil chronosequence of a glacier forefield

2011 ◽  
Vol 8 (1) ◽  
pp. 1275-1308 ◽  
Author(s):  
J. Esperschütz ◽  
A. Pérez-de-Mora ◽  
K. Schreiner ◽  
G. Welzl ◽  
F. Buegger ◽  
...  
Keyword(s):  
Food Web ◽  
Microbial Communities ◽  
Food Webs ◽  
Litter Decomposition ◽  
Glacier Forefield ◽  
Microbial Food Webs ◽  
Soil Age ◽  
Litter Degradation ◽  
And Function ◽  
The 19Th Century

Abstract. Microbial food webs are critical for efficient nutrient turnover providing the basis for functional and stable ecosystems. However, the successional development of such microbial food webs and their role in "young" ecosystems is unclear. Due to a continuous glacier retreat since the middle of the 19th century, glacier forefields have expanded offering an excellent opportunity to study food web development at differently developed soils. In the present study, litter degradation and the corresponding C fluxes into microbial communities were investigated along the forefield of the Damma glacier (Switzerland). 13C-enriched litter of the pioneering plant Leucanthemopsis alpina (L.) Heywood was incorporated into the soil at sites that have been free from ice for approximately 10, 60, 100 and more than 700 years. The structure and function of microbial communities were identified by 13C analysis of phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL). Results showed increasing microbial diversity and biomass, and enhanced proliferation of bacterial groups as ecosystem development progressed. Initially, litter decomposition proceeded faster at the more developed sites, but at the end of the experiment loss of litter mass was similar at all sites, once the more easily-degradable litter fraction was processed. As a result incorporation of 13C into microbial biomass was more evident during the first weeks of litter decomposition. 13C enrichments of both PLEL and PUFA biomarkers following litter incorporation were observed at all sites, suggesting similar microbial foodwebs at all stages of soil development. Nonetheless, the contribution of bacteria and actinomycetes to litter turnover became more pronounced as soil age increased in detriment of archaea, fungi and protozoa, more prominent in recently deglaciated terrain.

scholarly journals Effects of experimental warming, litter species, and presence of macroinvertebrates on litter decomposition and associated decomposers in a temperate mountain stream

2015 ◽  
Vol 72 (2) ◽  
pp. 206-216 ◽  
Author(s):  
Verónica Ferreira ◽  
Eric Chauvet ◽  
Cristina Canhoto
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Litter Decomposition ◽  
Castanea Sativa ◽  
Mountain Stream ◽  
Ambient Temperatures ◽  
C Cycle ◽  
Detrital Food Web ◽  
Water Courses ◽  
Aquatic Food

Small woodland streams make the majority of water courses in most watersheds. Litter decomposition is a key ecosystem process in these shaded streams, and its response to warming can have profound consequences for food webs and the carbon (C) cycle. However, these responses can be modulated by litter identity and the structure of the detrital food web. Here we report on a manipulative study aiming at evaluating the effects of warming (+2.8 °C), litter identity (chestnut (Castanea sativa) or oak (Quercus robur) litter), and the structure of the detrital food web (presence or absence of macroinvertebrates) on litter decomposition and decomposers in a small, temperate woodland stream. Warming significantly stimulated overall (microbial- + macroinvertebrate-driven) decomposition of oak and microbial-driven decomposition of chestnut. The similar shredder densities at elevated and ambient temperatures suggest that stimulated overall decomposition of oak resulted from increased activity of macroinvertebrate individuals. Stimulated microbial-driven decomposition of chestnut resulted from higher fungal activity with warming. Stimulation of litter decomposition by warming can lead to increases in the amount of C returned to the atmosphere and to a faster disappearance of litter from the benthos, with consequences to the C cycle and aquatic food webs.

scholarly journals Ecosystem Entanglement and the Propagation of Nutrient-Driven Instability

2020 ◽  
Author(s):  
Kevin S. McCann ◽  
A.S MacDougall ◽  
G.F. Fussmann ◽  
C. Bieg ◽  
K. Cazelles ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Nutrient Loading ◽  
Transport Theory ◽  
Nutrient Addition ◽  
Edible Plant ◽  
Nutrient Additions ◽  
Theoretical Synthesis ◽  
Human Modification ◽  
And Function

ABSTRACTAlmost 50 years ago, Michael Rosenzweig pointed out that nutrient addition can destabilize food webs, leading to loss of species and reduced ecosystem function through the paradox of enrichment. Around the same time, David Tilman demonstrated that increased nutrient loading would also be expected to cause competitive exclusion leading to deleterious changes in food web diversity. While both concepts have greatly illuminated general diversity-stability theory, we currently lack a coherent framework to predict how nutrients influence food web stability across a landscape. This is a vitally important gap in our understanding, given mounting evidence of serious ecological disruption arising from anthropogenic displacement of resources and organisms. Here, we combine contemporary theory on food webs and meta-ecosystems to show that nutrient additions are indeed expected to drive loss in stability and function in human-impacted regions. However, this loss in stability occurs not just from wild oscillations in population abundance, but more frequently from the complete loss of an equilibrium due to edible plant species being competitively excluded. In highly modified landscapes, spatial nutrient transport theory suggests that such instabilities can be amplified over vast distances from the sites of nutrient addition. Consistent with this theoretical synthesis, the empirical frequency of these distant propagating ecosystem imbalances appears to be growing. This synthesis of theory and empirical data suggests that human modification of the Earth’s ecological connectivity is “entangling” once distantly separated ecosystems, causing rapid, expansive, and costly nutrient-driven instabilities over vast areas of the planet. The corollary to this spatial nutrient theory, though -- akin to weak interaction theory from food web networks -- is that slow spatial nutrient pathways can be potent stabilizers by moderating flows across a landscape.

scholarly journals Strange invaders increase disturbance and promote generalists in an evolving food web

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonathan R. Morris ◽  
Korinna T. Allhoff ◽  
Fernanda S. Valdovinos
Keyword(s):  
Body Size ◽  
Food Web ◽  
Food Webs ◽  
Structure Stability ◽  
Generalist Species ◽  
Diet Specialization ◽  
Invading Species ◽  
Feeding Center ◽  
And Function ◽  
Food Web Model

AbstractThe patterns of diet specialization in food webs determine community structure, stability, and function. While specialists are often thought to evolve due to greater efficiency, generalists should have an advantage in systems with high levels of variability. Here we test the generalist-disturbance hypothesis using a dynamic, evolutionary food web model. Species occur along a body size axis with three traits (body size, feeding center, feeding range) that evolve independently and determine interaction strengths. Communities are assembled via ecological and evolutionary processes, where species biomass and persistence are driven by a bioenergetics model. New species are introduced either as mutants similar to parent species in the community or as invaders, with dissimilar traits. We introduced variation into communities by increasing the dissimilarity of invading species across simulations. We found that strange invaders increased the variability of communities which increased both the degree of generalism and the relative persistence of generalist species, indicating that invasion disturbance promotes the evolution of generalist species in food webs.

Networks, Extinction and Paleocommunity Food Webs

2010 ◽  
Vol 16 ◽  
pp. 143-161 ◽  
Author(s):  
Peter D. Roopnarine
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Food Webs ◽  
Trophic Interactions ◽  
Network Theory ◽  
Fossil Record ◽  
Numerical Approach ◽  
Ecological Diversity ◽  
Evolutionary Processes ◽  
Food Web Dynamics

Food webs represent trophic interactions among species in communities. Those interactions both structure and are structured by species richness, ecological diversity, and evolutionary processes. Geological and macroevolutionary timescales are therefore important to the understanding of food web dynamics, and there is a need for the consideration of paleocommunity food webs. The fossil record presents challenges in this regard, but the problem can be approached with combinatoric analysis and network theory. This paper is an introduction to the aspects of those disciplines relevant to the study of paleo-food webs, and explores a probabilistic and numerical approach.

scholarly journals Interplay between the paradox of enrichment and nutrient cycling in food webs

2018 ◽  
Author(s):  
Pierre Quévreux ◽  
Sébastien Barot ◽  
Élisa Thébault
Keyword(s):  
Nutrient Cycling ◽  
Food Web ◽  
Food Webs ◽  
Trophic Level ◽  
Temporal Variability ◽  
Ecosystem Functioning ◽  
Nutrient Inputs ◽  
Primary Producers ◽  
Paradox Of Enrichment ◽  
Food Web Dynamics

AbstractNutrient cycling is fundamental to ecosystem functioning. Despite recent major advances in the understanding of complex food web dynamics, food web models have so far generally ignored nutrient cycling. However, nutrient cycling is expected to strongly impact food web stability and functioning. To make up for this gap, we built an allometric and size structured food web model including nutrient cycling. By releasing mineral nutrients, recycling increases the availability of limiting resources for primary producers and links each trophic level to the bottom of food webs. We found that nutrient cycling can provide a significant part of the total nutrient supply of the food web, leading to a strong enrichment effect that promotes species persistence in nutrient poor ecosystems but leads to a paradox of enrichment at high nutrient inputs. The presence of recycling loops linking each trophic level to the basal resources weakly affects species biomass temporal variability in the food web. Recycling loops tend to slightly dampen the destabilising effect of nutrient enrichment on consumer temporal variability while they have opposite effects for primary producers. By considering nutrient cycling, this new model improves our understanding of the response of food webs to nutrient availability and opens perspectives to better link studies on food web dynamics and ecosystem functioning.

Adding the Ecosystem

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Closed System ◽  
Nutrient Recycling ◽  
Interaction Strength ◽  
Nonequilibrium Dynamics ◽  
Nutrient Pool ◽  
Food Web Dynamics ◽  
Resource Interactions ◽  
Consumer Resource

This chapter examines how nutrient recycling and decomposition affect the dynamics and stability of food webs. It first reviews some of the existing theory on detritus and food web dynamics before discussing the basics of a model that takes into account grazing food webs and whole ecosystems. It then describes the N-R-D (nutrient pool, resource, detritus) submodule as well as the full N-C-R-D (nutrient pool, consumer, resource, detritus) model. It also explores how detritus may act to distribute nutrients by considering a model that begets nonequilibrium dynamics. It shows that detritus tends to stabilize consumer–resource interactions relative to the purely community module (no recycling) because the detritus tends to fall out of phase with the resource–nutrient interaction. The addition of a consumer–resource incteraction to the N-R-D module, even in a closed system, eventually can drive overshoot dynamics and destabilization by increased production, coupling, or interaction strength.

scholarly journals Linking structure and function in food webs: maximization of different ecological functions generates distinct food web structures

2016 ◽  
Vol 85 (2) ◽  
pp. 537-547 ◽  
Author(s):  
Jian D. L. Yen ◽  
Reniel B. Cabral ◽  
Mauricio Cantor ◽  
Ian Hatton ◽  
Susanne Kortsch ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Structure And Function ◽  
Ecological Functions ◽  
And Function
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