scholarly journals Non-linear changes in modelled terrestrial ecosystems subjected to perturbations

2018 ◽  
Author(s):  
Tim Newbold ◽  
Derek P. Tittensor ◽  
Michael B. J. Harfoot ◽  
Jörn P. W. Scharlemann ◽  
Drew W. Purves
Keyword(s):  
Agricultural Land ◽  
Plant Biomass ◽  
Terrestrial Ecosystems ◽  
Natural World ◽  
Regime Shifts ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Ecological Communities ◽  
Ecological Processes ◽  
Non Linear

When perturbed ecosystems undergo rapid and non-linear changes, this can result in ‘regime shifts’ to an entirely different ecological state. The need to understand the extent, nature, magnitude and reversibility of these changes is urgent given the profound effects that humans are having on the natural world. It remains very challenging to empirically document non-linear changes and regime shifts within complex, real ecological communities, or even to demonstrate such shifts in simplified experimental systems. General ecosystem models, which simulate the dynamics of entire ecological communities based on a mechanistic representation of ecological processes, provide an alternative and novel way to project ecosystem changes across all scales and trophic levels and to forecast impact thresholds beyond which dramatic or irreversible changes may occur. We model non-linear changes in four terrestrial biomes subjected to human removal of plant biomass, such as occurs through agricultural land-use change. We find that irreversible and non-linear responses are predicted to be common where removal of vegetation exceeds 80% (a level that occurs across nearly 10% of the terrestrial surface), especially for organisms at higher trophic levels and in less productive ecosystems such as drylands. Very large, irreversible changes to the entire ecosystem structure are expected at levels of vegetation removal akin to those in the most intensively used real-world ecosystems. Our results suggest that the projected 21st century rapid increases in agricultural land conversion to feed an expanding human population, may lead to widespread trophic cascades and in some cases irreversible changes to the structure of ecological communities.

scholarly journals Trait-mediated trophic cascade creates enemy-free space for nesting hummingbirds

2015 ◽  
Vol 1 (8) ◽  
pp. e1500310 ◽  
Author(s):  
Harold F. Greeney ◽  
M. Rocio Meneses ◽  
Chris E. Hamilton ◽  
Eli Lichter-Marck ◽  
R. William Mannan ◽  
...  
Keyword(s):  
Climate Change ◽  
Habitat Fragmentation ◽  
Breeding Success ◽  
Indirect Effects ◽  
Trophic Cascade ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Ecological Communities ◽  
Top Predators ◽  
Enemy Free Space

The indirect effects of predators on nonadjacent trophic levels, mediated through traits of intervening species, are collectively known as trait-mediated trophic cascades. Although birds are important predators in terrestrial ecosystems, clear examples of trait-mediated indirect effects involving bird predators have almost never been documented. Such indirect effects are important for structuring ecological communities and are likely to be negatively impacted by habitat fragmentation, climate change, and other factors that reduce abundance of top predators. We demonstrate that hummingbirds in Arizona realize increased breeding success when nesting in association with hawks. An enemy-free nesting space is created when jays, an important source of mortality for hummingbird nests, alter their foraging behavior in the presence of their hawk predators.

scholarly journals Effects of climate and overfishing on zooplankton dynamics and ecosystem structure: regime shifts, trophic cascade, and feedback loops in a simple ecosystem

2008 ◽  
Vol 65 (3) ◽  
pp. 302-310 ◽  
Author(s):  
Christian Möllmann ◽  
Bärbel Müller-Karulis ◽  
Georgs Kornilovs ◽  
Michael A. St John
Keyword(s):  
Time Series ◽  
Trophic Cascade ◽  
World Ocean ◽  
Regime Shifts ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Regime Changes ◽  
Key Species ◽  
Zooplankton Dynamics ◽  
Induced Changes

Abstract Möllmann, C., Müller-Karulis, B., Kornilovs, G., and St John, M. A. 2008. Effects of climate and overfishing on zooplankton dynamics and ecosystem structure: regime shifts, trophic cascade, and feeback loops in a simple ecosystem. – ICES Journal of Marine Science, 65: 302–310. The Central Baltic Sea is the largest brackish waterbody in the world ocean, containing a highly productive but low-diversity ecosystem. Climate-induced changes in hydrography recently caused an ecosystem regime shift with changes at all trophic levels. The most pronounced changes in the ecosystem occurred at the zooplankton and fish trophic levels. In the zooplankton, dominance changed between the copepods Pseudocalanus acuspes and Acartia spp., a result of reduced salinities and increased temperatures. The change in hydrography also affected the reproductive success of the major fish species, resulting in a change in dominance from the piscivorous cod (Gadus morhua) to the planktivorous sprat (Sprattus sprattus). First, we investigate statistically the occurrence of regime shifts in time-series of key hydrographic variables and the biomass time-series of key species. Second, we demonstrate a three-level trophic cascade involving zooplankton. Finally, we model the ecosystem effects of the abiotic and biotic changes on copepod biomass and recruitment of fish stocks. Our results demonstrate the linkage between climate-induced zooplankton and fish regime changes, and how overfishing amplified the climate-induced changes at both trophic levels. Hence, our study demonstrates (i) the multiple pathways along which climatic and anthropogenic pressures can propagate through the foodweb; (ii) how both effects act synergistically to cause and stabilize regime changes; and (iii) the crucial role of zooplankton in mediating these ecosystem changes.

scholarly journals An empirical model of the Baltic Sea reveals the importance of social dynamics for ecological regime shifts

2015 ◽  
Vol 112 (35) ◽  
pp. 11120-11125 ◽  
Author(s):  
Steven J. Lade ◽  
Susa Niiranen ◽  
Jonas Hentati-Sundberg ◽  
Thorsten Blenckner ◽  
Wiebren J. Boonstra ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Social Dynamics ◽  
Environmental Changes ◽  
Ecological Model ◽  
Model Development ◽  
Terrestrial Ecosystems ◽  
Regime Shifts ◽  
Ecological Data ◽  
Ecological Processes ◽  
Social Ecological

Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such shifts. Here, we used generalized modeling to develop a coupled social–ecological model that integrated rich social and ecological data to investigate the role of social dynamics in the 1980s Baltic Sea cod boom and collapse. We showed that psychological, economic, and regulatory aspects of fisher decision making, in addition to ecological interactions, contributed both to the temporary persistence of the cod boom and to its subsequent collapse. These features of the social–ecological system also would have limited the effectiveness of stronger fishery regulations. Our results provide quantitative, empirical evidence that incorporating social dynamics into models of natural resources is critical for understanding how resources can be managed sustainably. We also show that generalized modeling, which is well-suited to collaborative model development and does not require detailed specification of causal relationships between system variables, can help tackle the complexities involved in creating and analyzing social–ecological models.

scholarly journals Aridity Decouples C:N:P Stoichiometry Across Multiple Trophic Levels in Terrestrial Ecosystems

Ecosystems ◽  
2017 ◽  
Vol 21 (3) ◽  
pp. 459-468 ◽  
Author(s):  
Manuel Delgado-Baquerizo ◽  
David J. Eldridge ◽  
Fernando T. Maestre ◽  
Victoria Ochoa ◽  
Beatriz Gozalo ◽  
...  
Keyword(s):  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
C:N:P Stoichiometry

scholarly journals Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient

2010 ◽  
Vol 22 (6) ◽  
pp. 742-748 ◽  
Author(s):  
Tancredi Caruso ◽  
Ian D. Hogg ◽  
Roberto Bargagli
Keyword(s):  
Abiotic Factors ◽  
Relevant Literature ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Climatic Conditions ◽  
Trophic Levels ◽  
Terrestrial Arthropods ◽  
Victoria Land ◽  
Dispersal Capability ◽  
Modelling Techniques

AbstractBiotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e.g. predators); thus, it is often assumed that species’ distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e.g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

scholarly journals Linking Genes to Traits in Fungi

2021 ◽  
Author(s):  
A. L. Romero-Olivares ◽  
E. W. Morrison ◽  
A. Pringle ◽  
S. D. Frey
Keyword(s):  
Organic Matter ◽  
Nitrogen Uptake ◽  
Brown Rot ◽  
Terrestrial Ecosystems ◽  
Organic Matter Decomposition ◽  
Gene Frequencies ◽  
Ecological Processes ◽  
Linked Gene ◽  
Carbon Cycles ◽  
Brown Rot Fungi

AbstractFungi are mediators of the nitrogen and carbon cycles in terrestrial ecosystems. Examining how nitrogen uptake and organic matter decomposition potential differs in fungi can provide insight into the underlying mechanisms driving fungal ecological processes and ecosystem functioning. In this study, we assessed the frequency of genes encoding for specific enzymes that facilitate nitrogen uptake and organic matter decomposition in 879 fungal genomes with fungal taxa grouped into trait-based categories. Our linked gene-trait data approach revealed that gene frequencies vary across and within trait-based groups and that trait-based categories differ in trait space. We present two examples of how this linked gene-trait approach can be used to address ecological questions. First, we show that this type of approach can help us better understand, and potentially predict, how fungi will respond to environmental stress. Specifically, we found that trait-based categories with high nitrogen uptake gene frequency increased in relative abundance when exposed to high soil nitrogen enrichment. Second, by comparing frequencies of nitrogen uptake and organic matter decomposition genes, we found that most ectomycorrhizal fungi in our dataset have similar gene frequencies to brown rot fungi. This demonstrates that gene-trait data approaches can shed light on potential evolutionary trajectories of life history traits in fungi. We present a framework for exploring nitrogen uptake and organic matter decomposition gene frequencies in fungal trait-based groups and provide two concise examples on how to use our framework to address ecological questions from a mechanistic perspective.

scholarly journals Decoupled taxonomic and ecological recoveries from the Permo-Triassic extinction

2018 ◽  
Vol 4 (10) ◽  
pp. eaat5091 ◽  
Author(s):  
Haijun Song ◽  
Paul B. Wignall ◽  
Alexander M. Dunhill
Keyword(s):  
Time Scales ◽  
Carrying Capacity ◽  
Mass Extinction ◽  
Marine Species ◽  
Taxonomic Diversity ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Top Down ◽  
Structure Building

The Permian-Triassic mass extinction was the worst crisis faced by life; it killed >90% of marine species in less than 0.1 million years (Ma). However, knowledge of its macroecological impact over prolonged time scales is limited. We show that marine ecosystems dominated by non-motile animals shifted to ones dominated by nektonic groups after the extinction. In Triassic oceans, animals at high trophic levels recovered faster than those at lower levels. The top-down rebuilding of marine ecosystems was still underway in the latest Triassic, ~50 Ma after the extinction, and contrasts with the ~5-Ma recovery required for taxonomic diversity. The decoupling between taxonomic and ecological recoveries suggests that a process of vacant niche filling before reaching the maximum environmental carrying capacity is independent of ecosystem structure building.

Cooperation between Species

2017 ◽  
Author(s):  
Raymond Pierotti ◽  
Brandy R. Fogg
Keyword(s):  
Cooperative Behavior ◽  
Natural World ◽  
Western Science ◽  
Ecological Communities ◽  
Cooperative Hunting ◽  
Wide Range

This chapter reviews the study of cooperative behavior between species, with emphasis on examples of cooperative hunting found in a wide range of species. Seen in this context, the idea of cooperative hunting between humans and wolves that evolved into present relationships with dogs does not seem unusual or surprising. The chapter then critiques the proposal that competition between species is more important than cooperation in structuring ecological communities, discussing how this notion leads to a suite of ideas philosophically separating humans from the rest of the natural world. In many ways Western science is unintentionally complicit in such thinking. The chapter concludes by discussing complex cooperation, including long-term relationships between members of different species.

scholarly journals Genetic diversity increases food-web persistence in the face of climate warming

2020 ◽  
Author(s):  
Matthew A. Barbour ◽  
Daniel J. Kliebenstein ◽  
Jordi Bascompte
Keyword(s):  
Genetic Diversity ◽  
Food Web ◽  
Allelic Variation ◽  
Chemical Defenses ◽  
Trophic Levels ◽  
Raw Material ◽  
Ecological Communities ◽  
Warming Scenario ◽  
The Face ◽  
Loss Of Genetic Diversity

Genetic diversity provides the raw material for species to adapt and persist in the face of climate change. Yet, the extent to which these genetic effects scale at the level of ecological communities remains unclear. Here we experimentally test the effect of plant genetic diversity on the persistence of an insect food web under a current and future warming scenario. We found that plant genetic diversity increased food-web persistence by increasing the intrinsic growth rates of species across multiple trophic levels. This positive effect was robust to a 3°C warming scenario and resulted from allelic variation at two genes that control the biosynthesis of chemical defenses. Our results suggest that the ongoing loss of genetic diversity may undermine the persistence and functioning of ecosystems in a changing world.One Sentence SummaryThe loss of genetic diversity accelerates the extinction of inter-connected species from an experimental food web.

scholarly journals Soil Quality in the Poganis, Ramnei and Doclin Hills Measures of improvment

2019 ◽  
Vol 70 (7) ◽  
pp. 2463-2470
Author(s):  
Lucian Nita ◽  
Dorin Tarau ◽  
Simona Nita ◽  
Alina Heghes ◽  
Radu Bertici ◽  
...  
Keyword(s):  
Agricultural Land ◽  
Soil Formation ◽  
Terrestrial Ecosystems ◽  
Scientific Work ◽  
Basic Information ◽  
High Demand ◽  
Soil Resources ◽  
Genetic Types ◽  
Improvement Measures ◽  
Formation And Evolution

The purpose of current research is part of the current scientific work and practice regarding the accumulation of knowledge on the structure and characteristics of the edaphic envelope and its quality in order to establish measures for its improvement. The researched issue covers an area of 113940 ha (of which 77039 ha, 67.61% are agricultural land), located in the Poganis, Ramnei and Doclin hills, namely Barzavei Plain. The paper provides basic information and methodological elements regarding the classification and evaluation of soil resources, thus integrating itself in the broader field of complex studies of natural resources and their valorisation thus assuring the environmental protection. This research takes place at a time when there is a high demand of education in soil-related issues from its perspective as a basis for the existence of human communities, component and support of terrestrial ecosystems. From this perspective, the physico-geographic conditions of soil formation and evolution are briefly, but succinctly presented, mentioning the way in which the particularities of the area within the space taken into consideration, of only 113940 ha as a stretch, determine a great diversity of ecological conditions. They are generated by the variability of the factors (cosmic-atmospheric and telluric-edaphic), for which the main processes of formation and evolution have achieved a different development and intensity, the result of which are different genetic types of soils (related or totally different) in constant evolution and demanding specific improvement measures.

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