Interaction Diversity Maintains Resiliency in a Frequently Disturbed Ecosystem

Dell, Jane E.; Salcido, Danielle M.; Lumpkin, Will; Richards, Lora A.; Pokswinski, Scott; Loudermilk, E. Louise; O’Brien, Joseph J.; Dyer, Lee A.

doi:10.3389/fevo.2019.00145

Cited by 26 publications

(13 citation statements)

References 45 publications

(68 reference statements)

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“…Our metacommunity study, which, to our knowledge, is the 1 st to describe the physical and biological model of a river network across multiple hydrological phases at such a fine spatiotemporal scale, confirmed that the relative roles of niche-based and dispersal-based metacommunity processes change over time. We suggest that this conclusion may apply to other dynamic freshwater, terrestrial, and marine ecosystems (e.g., Gerisch 2014, Dell et al 2019.…”

Section: Discussionmentioning

confidence: 65%

Dispersal limitation by structures is more important than intermittent drying effects for metacommunity dynamics in a highly fragmented river network

et al. 2021

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In the Anthropocene, river networks are globally threatened by human activities, creating dramatic consequences for aquatic biodiversity. Permanent and temporary fragmentation by manmade structures and drying events, respectively, are both increasing in rivers worldwide. Although both of these fragmentation types can limit species dispersal, their individual and combined effects in shaping metacommunity dynamics at both local (site-level) and regional (network-level) scales have not been explored. Here, we examined whether processes structuring aquatic invertebrate metacommunities vary through time in response to flow variability in a river network affected by drying and severe fragmentation by manmade structures. We also compared the relative influences of permanent and temporary fragmentation on metacommunity dynamics and hypothesized that permanent fragmentation would be the primary determinant of metacommunity dynamics. We conducted an intensive sampling effort (30 sampling sites Â 6 dates) and measured 12 local environmental variables and 4 spatial distances to assess the relative importance of niche-and dispersal-based processes on benthic invertebrate metacommunities across hydrological phases. Spatial distances considered here were overland, network, and 2 fragmentation distances integrating the permanent fragmentation by manmade structures and temporary fragmentation by drying. We used Mantel tests to identify relationships between community dissimilarities and environmental and spatial distance matrices. We identified temporal variability in metacommunity processes with a predominant role of dispersal and no effect of niche-based processes. Metacommunities were shaped primarily by permanent fragmentation, whereas we detected no effect of fragmentation by network-scale drying. Dispersal-based metacommunity processes varied over time, following the wet-dry cycles that characterize dynamic river networks. Our results suggest the importance of key hydrological phases that should be incorporated into conservation perspectives. In addition, we highlight the need to quantify context dependency in metacommunity studies to optimize biodiversity conservation strategies in river-network ecosystems.

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Section: Discussionmentioning

confidence: 65%

Dispersal limitation by structures is more important than intermittent drying effects for metacommunity dynamics in a highly fragmented river network

et al. 2021

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“…However, processes such as natural disturbances (wind, bark beetles, wildfire) and human land‐use decisions also influence forest dynamics and resilience. Natural disturbances can enhance forest resilience by fostering response diversity (Dell et al., 2019) but changing natural disturbance regimes could also disrupt forest recovery and therefore reduce resilience (Hansen et al., 2018; Turner, Braziunas, Hansen, & Harvey, 2019). There is a high degree of uncertainty in projections of future disturbance regimes and disturbance interactions as climate changes.…”

Section: Discussionmentioning

confidence: 99%

Climate change causes critical transitions and irreversible alterations of mountain forests

Albrich

Rammer

Seidl

2020

Global Change Biology

143

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Mountain forests are at particular risk of climate change impacts due to their temperature limitation and high exposure to warming. At the same time, their complex topography may help to buffer the effects of climate change and create climate refugia. Whether climate change can lead to critical transitions of mountain forest ecosystems and whether such transitions are reversible remain incompletely understood. We investigated the resilience of forest composition and size structure to climate change, focusing on a mountain forest landscape in the Eastern Alps. Using the individual‐based forest landscape model iLand, we simulated ecosystem responses to a wide range of climatic changes (up to a 6°C increase in mean annual temperature and a 30% reduction in mean annual precipitation), testing for tipping points in vegetation size structure and composition under different topography scenarios. We found that at warming levels above +2°C a threshold was crossed, with the system tipping into an alternative state. The system shifted from a conifer‐dominated landscape characterized by large trees to a landscape dominated by smaller, predominantly broadleaved trees. Topographic complexity moderated climate change impacts, smoothing and delaying the transitions between alternative vegetation states. We subsequently reversed the simulated climate forcing to assess the ability of the landscape to recover from climate change impacts. The forest landscape showed hysteresis, particularly in scenarios with lower precipitation. At the same mean annual temperature, equilibrium vegetation size structure and species composition differed between warming and cooling trajectories. Here we show that even moderate warming corresponding to current policy targets could result in critical transitions of forest ecosystems and highlight the importance of topographic complexity as a buffering agent. Furthermore, our results show that overshooting ambitious climate mitigation targets could be dangerous, as ecological impacts can be irreversible at millennial time scales once a tipping point has been crossed.

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“…While some links between taxonomic and functional diversity have been explored in some highly dynamic ecosystems (e.g. terrestrial communities exposed to floods or fire-adapted forest, Gerisch 2014, Dell et al 2019, these have been mostly restricted to static snapshot views of community patterns and, to date, their temporal dynamics have been overlooked.…”

Section: Introductionmentioning

confidence: 99%

Drying determines the temporal dynamics of stream invertebrate structural and functional beta diversity

et al. 2019

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Assembly processes shaping ecological communities can vary over time following variations of environmental conditions at different scales. Such temporal dynamism is exacerbated by climate change and increasing extreme events, and recent evidence suggests that, in turn, community composition and functions can vary substantially. However, empirical relationships between the spatio‐temporal dynamics of communities and that extreme events altering ecosystems are poorly investigated. We quantified the temporal dynamics of stream invertebrate communities over two years across 11 river basins prone to drying, covering a large geographical area of France. We tested predictions on the influence of the spatial arrangement and temporal dynamics of drying events across river networks. Combining a high temporal resolution of community description from taxonomic and functional perspectives, we quantified beta diversity over time and space and partitioned them into additive components: replacement of taxa and richness difference. Frequency and duration of drying events were precisely quantified and basins were classified based on the location of the drying events. We found a strong influence of the spatial drying pattern on the dissimilarities of community composition between sites. The high temporal variability of community structure was directly related to the frequency and duration of drying events. This temporal dynamism of communities was also strongly affected by the spatial drying pattern, indicating that fragmentation had a stronger effect on recolonisation processes for upstream‐drying basins. Finally, biological traits were unevenly distributed in space and time, suggesting a lack of functional redundancy that could have strong implications for ecosystem functions and services. The high temporal dynamics of communities highlighted in this study challenge the current definition of reference conditions in intermittent rivers, and the community sensitivity to frequency and duration of drying suggest that climate change might lead community dynamics to be increasingly driven by stochastic environmental variability.

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Interaction Diversity Maintains Resiliency in a Frequently Disturbed Ecosystem

Cited by 26 publications

References 45 publications

Dispersal limitation by structures is more important than intermittent drying effects for metacommunity dynamics in a highly fragmented river network

Dispersal limitation by structures is more important than intermittent drying effects for metacommunity dynamics in a highly fragmented river network

Climate change causes critical transitions and irreversible alterations of mountain forests

Drying determines the temporal dynamics of stream invertebrate structural and functional beta diversity

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