scholarly journals Biocrust as one of multiple stable states in global drylands

2020 ◽  
Vol 6 (39) ◽  
pp. eaay3763 ◽  
Author(s):  
Ning Chen ◽  
Kailiang Yu ◽  
Rongliang Jia ◽  
Jialing Teng ◽  
Changming Zhao
Keyword(s):  
Vascular Plants ◽  
Stable State ◽  
Aridity Index ◽  
Bare Soil ◽  
Biogeochemical Cycles ◽  
Stable States ◽  
Alternative Stable State ◽  
Bistable Region ◽  
Fold Bifurcation ◽  
Multiple Stable States

Biocrusts cover ~30% of global drylands with a prominent role in the biogeochemical cycles. Theoretically, biocrusts, vascular plants, and bare soil can represent multiple stable states in drylands. However, no empirical evidence for the existence of a biocrust stable state has been reported. Here, using a global drylands dataset, we found that biocrusts form an alternative stable state (biocrust cover, ~80%; vascular cover, ≤10%) besides bare soil (both biocrust and vascular cover, ≤10%) and vascular plants (vascular cover, >50%; biocrust cover, ~5%). The pattern of multiple stable states associated with biocrusts differs from the classic fold bifurcation, and values of the aridity index in the range of 0 to 0.6 define a bistable region where multiple stable states coexist. This study empirically demonstrates the existence and thresholds of multiple stable states associated with biocrusts along climatic gradients and thus may greatly contribute to conservation and restoration of global drylands.

scholarly journals Path-dependent institutions drive alternative stable states in conservation

2018 ◽  
Vol 116 (2) ◽  
pp. 689-694 ◽  
Author(s):  
Edward W. Tekwa ◽  
Eli P. Fenichel ◽  
Simon A. Levin ◽  
Malin L. Pinsky
Keyword(s):  
Renewable Resources ◽  
Path Dependence ◽  
Alternative Stable States ◽  
Stable State ◽  
Empirical Support ◽  
Stable States ◽  
Alternative Stable State ◽  
Important Challenge ◽  
Quantitative Analyses ◽  
Path Dependent

Understanding why some renewable resources are overharvested while others are conserved remains an important challenge. Most explanations focus on institutional or ecological differences among resources. Here, we provide theoretical and empirical evidence that conservation and overharvest can be alternative stable states within the same exclusive-resource management system because of path-dependent processes, including slow institutional adaptation. Surprisingly, this theory predicts that the alternative states of strong conservation or overharvest are most likely for resources that were previously thought to be easily conserved under optimal management or even open access. Quantitative analyses of harvest rates from 217 intensely managed fisheries supports the predictions. Fisheries’ harvest rates also showed transient dynamics characteristic of path dependence, as well as convergence to the alternative stable state after unexpected transitions. This statistical evidence for path dependence differs from previous empirical support that was based largely on case studies, experiments, and distributional analyses. Alternative stable states in conservation appear likely outcomes for many cooperatively managed renewable resources, which implies that achieving conservation outcomes hinges on harnessing existing policy tools to navigate transitions.

scholarly journals Shifting States, Altered Fates: Divergent Fuel Moisture Responses after High Frequency Wildfire in an Obligate Seeder Eucalypt Forest

Forests ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 436 ◽  
Author(s):  
Jamie Burton ◽  
Jane Cawson ◽  
Philip Noske ◽  
Gary Sheridan
Keyword(s):  
High Frequency ◽  
Alternative Stable States ◽  
Stable State ◽  
Fuel Moisture ◽  
Stable States ◽  
Alternative Stable State ◽  
Obligate Seeder ◽  
Time Since Fire ◽  
Mountain Ash ◽  
Moisture Dynamics

High frequency wildfires can shift the structure and composition of obligate seeder forests and initiate replacement with alternative vegetation states. In some forests, the alternative stable state is drier and more easily burned by subsequent fires, driving a positive feedback that promotes further wildfire and perpetuates alternative stable states. Mountain Ash (Eucalyptus regnans (F.Muell.)) forests are highly valued for their biodiversity, water, timber and carbon. Fires are a natural part of the lifecycle of these forests, but too frequent fires can eliminate Mountain Ash and trigger a transition to lower stature, non-eucalypt forests which are dominated by understorey species. This study sought to better understand the fuel moisture dynamics of alternative stable states resulting from high frequency wildfires. A vegetation mosaic in the Central Highlands, Victoria created a unique opportunity to measure fuel moisture in adjacent forest stands that differed in overstorey species composition and time since fire. Specifically, we measured fuel moisture and microclimate at two eucalypt sites (9 and 79 years old) and three non-eucalypt sites (two 9 year old and one 79 year old). Fuel availability, defined here as the number of days surface fuels were below 16% and dry enough to ignite and sustain fire, was calculated to estimate flammability. Fuel availability differed between sites, particularly as a function of time since fire, with recently burnt sites available to burn more often (4–17 versus 0–3 days). There were differences in fuel availability between non-eucalypt sites of the same age, suggesting that high frequency fire does not always lead to the same vegetation condition or outcome for fuel availability. This indicates there is potential for both positive and negative flammability feedbacks following state transition depending on the composition of the non-eucalypt state. This is the first study to provide empirical insight into the fuel moisture dynamics of alternative stable states in Mountain Ash forests.

scholarly journals Transient invaders can induce shifts between alternative stable states of microbial communities

2020 ◽  
Vol 6 (8) ◽  
pp. eaay8676 ◽  
Author(s):  
Daniel R. Amor ◽  
Christoph Ratzke ◽  
Jeff Gore
Keyword(s):  
Environmental Changes ◽  
Alternative Stable States ◽  
Stable State ◽  
Natural Soil ◽  
Stable States ◽  
Alternative Stable State ◽  
Community Shift ◽  
Invader Species ◽  
Potential Impact ◽  
And Function

Microbial dispersal often leads to the arrival of outsider organisms into ecosystems. When their arrival gives rise to successful invasions, outsider species establish within the resident community, which can markedly alter the ecosystem. Seemingly less influential, the potential impact of unsuccessful invaders that interact only transiently with the community has remained largely ignored. Here, we experimentally demonstrate that these transient invasions can induce a lasting transition to an alternative stable state, even when the invader species itself does not survive the transition. First, we develop a mechanistic understanding of how environmental changes caused by these transient invaders can drive a community shift in a simple, bistable model system. Beyond this, we show that transient invaders can also induce switches between stable states in more complex communities isolated from natural soil samples. Our results demonstrate that short-term interactions with an invader species can induce lasting shifts in community composition and function.

scholarly journals Transient invaders can induce shifts between alternative stable states of microbial communities

2019 ◽  
Author(s):  
Daniel R. Amor ◽  
Christoph Ratzke ◽  
Jeff Gore
Keyword(s):  
Community Composition ◽  
Environmental Changes ◽  
Alternative Stable States ◽  
Stable State ◽  
Natural Soil ◽  
Stable States ◽  
Alternative Stable State ◽  
Community Shift ◽  
Invader Species ◽  
And Function

AbstractMicrobial dispersal often leads to the arrival of outsider organisms into ecosystems. When their arrival give rise to successful invasions, outsider species establish within the resident community, which can dramatically alter the ecosystem. Seemingly less influential, the potential impact of unsuccessful invaders that interact only transiently with the community has remained largely ignored. Here, we experimentally demonstrate that such transient invasions can perturb the stability of microbial ecosystems and induce a lasting transition to an alternative stable state, even when the invader species itself does not survive the transition. First, we develop a mechanistic understanding of how environmental changes caused by such transient invaders can drive a community shift in a simple, bistable model system. Beyond this, we show that transient invaders can also induce switches between stable states in more complex communities isolated from natural soil samples. Our results demonstrate that short-term interactions with an invader species can induce lasting shifts in community composition and function.One Sentence SummaryTransient invaders can cause lasting shifts in community composition and function.

scholarly journals Different coastal marsh sites reflect similar topographic conditions for bare patches and vegetation recovery

2020 ◽  
Author(s):  
Chen Wang ◽  
Lennert Schepers ◽  
Matthew L. Kirwan ◽  
Enrica Belluco ◽  
Andrea D'Alpaos ◽  
...  
Keyword(s):  
Stable State ◽  
Venice Lagoon ◽  
State Theory ◽  
Sediment Supply ◽  
Coastal Marsh ◽  
Tidal Range ◽  
Unstable State ◽  
Stable States ◽  
Alternative Stable State ◽  
Subsequent Loss

Abstract. The presence of bare patches within otherwise vegetated coastal marshes is sometimes considered to be a symptom of marsh die-back and the subsequent loss of important ecosystem services. Here we studied the topographical conditions determining the presence and revegetation of bare patches in three marsh sites with contrasting tidal range, sediment supply and plant species: the Scheldt Estuary (the Netherlands), Venice Lagoon (Italy), and Blackwater Marshes (Maryland, USA). We analyzed topographic properties of bare patches, including elevation, size, distance and connectivity to channels based on GIS analyses of aerial and LIDAR imagery. Our results demonstrate that across the different marsh sites, bare patches connected to channels occur most frequently at the lowest elevations and farthest distance from the main channels. Bare patches disconnected from channels occur most frequently at intermediate elevations and distances from channels, and vegetated marshes dominate at highest elevations and shortest distances from channels. Revegetation in bare patches is observed in only one site with the highest tidal range and highest sediment availability, and preferentially occurs from the edges of small unconnected bare patches at intermediate elevations and intermediate distances from channels. Our results are discussed within the alternative stable state theory. We suggest the existence of two stable states, a high-elevated vegetated state close to channels that tends to remain high and vegetated, and a low-elevated state of bare connected patches far from channels that tends to remain bare, with an unstable state at intermediate channel distances where bare patches may form and rapidly become revegetated.

Anisotropic, Adaptive, and Asymmetric Multi-Stability From Origami Folding

2017 ◽  
Author(s):  
Suyi Li
Keyword(s):  
Three Dimensional ◽  
Stable State ◽  
Physical Origin ◽  
Stable States ◽  
Stability Properties ◽  
Dimensional Shape ◽  
Multiple Stable States ◽  
Three Dimensional Shape ◽  
Unstable States ◽  
Lower Dimensional

This study investigates the elastic multi-stability properties originated from origami folding. Specifically, it focuses on a space-filling architecture consisting of stacked Miura-ori sheets, which exhibits multiple stable states corresponding to different internal folding configurations. The fundamentally three-dimensional shape transformations from origami folding impart several unique properties that are unachievable from the lower dimensional mechanisms. They are (1) anisotropy-arrangement of the stable and unstable states fundamentally differs along different principle axes; (2) adaptability-stable states can be generated or eliminated via simple pressurization; and (3) asymmetry-the energy barrier of switching from one stable state to another can be significantly higher than the opposite switch, even though the two stable states have the same energy level. These unique stability properties could be harnessed to create a wide variety of adaptive functionalities, such as programmable stiffness, impulsive actuation, and mechanical diode effect. The purpose of this paper is to examine the physical origin of the three stability properties and their correlations to the origami design. Results of this of study can foster the creation of novel multi-functional structures and materials based on origami.

scholarly journals Bimodality of woody cover and biomass across the precipitation gradient in West Africa

2014 ◽  
Vol 5 (2) ◽  
pp. 257-270 ◽  
Author(s):  
Z. Yin ◽  
S. C. Dekker ◽  
B. J. J. M. van den Hurk ◽  
H. A. Dijkstra
Keyword(s):  
Aboveground Biomass ◽  
Vegetation Structure ◽  
Stable State ◽  
Transient State ◽  
Stable States ◽  
Data Set ◽  
Climate Conditions ◽  
Vertical Leaf ◽  
Woody Cover ◽  
Multiple Stable States

Abstract. Multiple states of woody cover under similar climate conditions are found in both conceptual models and observations. Due to the limitation of the observed woody cover data set, it is unclear whether the observed bimodality is caused by the presence of multiple stable states or is due to dynamic growth processes of vegetation. In this study, we combine a woody cover data set with an aboveground biomass data set to investigate the simultaneous occurrences of savanna and forest states under the same precipitation forcing. To interpret the results we use a recently developed vegetation dynamics model (the Balanced Optimality Structure Vegetation Model), in which the effect of fires is included. Our results show that bimodality also exists in aboveground biomass and retrieved vegetation structure. In addition, the observed savanna distribution can be understood as derived from a stable state and a slightly drifting (transient) state, the latter having the potential to shift to the forest state. Finally, the results indicate that vegetation structure (horizontal vs. vertical leaf extent) is a crucial component for the existence of bimodality.

scholarly journals Successional dynamics and alternative stable states in a saline activated sludge microbial community over 9 years

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Yulin Wang ◽  
Jun Ye ◽  
Feng Ju ◽  
Lei Liu ◽  
Joel A. Boyd ◽  
...  
Keyword(s):  
Microbial Community ◽  
Activated Sludge ◽  
Alternative Stable States ◽  
Treatment Plant ◽  
Stable State ◽  
Comparative Genomic ◽  
Operational Parameters ◽  
Stable States ◽  
Alternative Stable State ◽  
Analysis Of Dynamics

Abstract Background Microbial communities in both natural and applied settings reliably carry out myriads of functions, yet how stable these taxonomically diverse assemblages can be and what causes them to transition between states remains poorly understood. We studied monthly activated sludge (AS) samples collected over 9 years from a full-scale wastewater treatment plant to answer how complex AS communities evolve in the long term and how the community functions change when there is a disturbance in operational parameters. Results Here, we show that a microbial community in activated sludge (AS) system fluctuated around a stable average for 3 years but was then abruptly pushed into an alternative stable state by a simple transient disturbance (bleaching). While the taxonomic composition rapidly turned into a new state following the disturbance, the metabolic profile of the community and system performance remained remarkably stable. A total of 920 metagenome-assembled genomes (MAGs), representing approximately 70% of the community in the studied AS ecosystem, were recovered from the 97 monthly AS metagenomes. Comparative genomic analysis revealed an increased ability to aggregate in the cohorts of MAGs with correlated dynamics that are dominant after the bleaching event. Fine-scale analysis of dynamics also revealed cohorts that dominated during different periods and showed successional dynamics on seasonal and longer time scales due to temperature fluctuation and gradual changes in mean residence time in the reactor, respectively. Conclusions Our work highlights that communities can assume different stable states under highly similar environmental conditions and that a specific disturbance threshold may lead to a rapid shift in community composition.

Trapped liquid drop in a microchannel: Multiple stable states

2013 ◽  
Vol 87 (6) ◽  
Author(s):  
Zhengjia Wang ◽  
Cheng-Chung Chang ◽  
Siang-Jie Hong ◽  
Yu-Jane Sheng ◽  
Heng-Kwong Tsao
Keyword(s):  
Liquid Drop ◽  
Stable States ◽  
Multiple Stable States

Large herbivores suppress liana infestation in an African savanna

2021 ◽  
Vol 118 (41) ◽  
pp. e2101676118
Author(s):  
Tyler C. Coverdale ◽  
Ryan D. O’Connell ◽  
Matthew C. Hutchinson ◽  
Amanda Savagian ◽  
Tyler R. Kartzinel ◽  
...  
Keyword(s):  
Stable State ◽  
Life Forms ◽  
Tree Canopy ◽  
Alternative Stable State ◽  
African Savanna ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Woody Vines ◽  
Plant Life Forms ◽  
Canopy Area

African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana–tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.

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