Aspects of the Stability and Resilience of Savanna Ecosystems

1982 ◽  
pp. 556-590 ◽  
Author(s):  
B. H. Walker ◽  
I. Noy-Meir
Keyword(s):  
The Stability ◽  
Stability And Resilience

scholarly journals The crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa

2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Blessing Mhlanga ◽  
Laura Ercoli ◽  
Elisa Pellegrino ◽  
Andrea Onofri ◽  
Christian Thierfelder
Keyword(s):  
Crop Rotation ◽  
Southern Africa ◽  
Cropping Systems ◽  
Conservation Agriculture ◽  
Conventional Tillage ◽  
Yield Stability ◽  
No Tillage ◽  
The Stability ◽  
Stability And Resilience

AbstractConservation agriculture has been promoted to sustainably intensify food production in smallholder farming systems in southern Africa. However, farmers have rarely fully implemented all its components, resulting in different combinations of no-tillage, crop rotation, and permanent soil cover being practiced, thus resulting in variable yield responses depending on climatic and soil conditions. Therefore, it is crucial to assess the effect of conservation agriculture components on yield stability. We hypothesized that the use of all three conservation agriculture components would perform the best, resulting in more stable production in all environments. We evaluated at, eight trial locations across southern Africa, how partial and full implementation of these components affected crop yield and yield stability compared with conventional tillage alone or combined with mulching and/or crop rotation. Grain yield and shoot biomass of maize and cowpea were recorded along with precipitation for 2 to 5 years. Across different environments, the addition of crop rotation and mulch to no-tillage increased maize grain by 6%, and the same practices added to conventional tillage led to 13% yield increase. Conversely, adding only mulch or crop rotation to no-tillage or conventional tillage led to lower or equal maize yield. Stability analyses based on Shukla’s index showed for the first time that the most stable systems are those in which mulch is added without crop rotation. Moreover, the highest yielding systems were the least stable. Finally, additive main effects and multiplicative interaction analysis allowed clarifying that mulch added to no-tillage gives stable yields on sandy soil with high rainfall. Similarly, mulch added to conventional tillage gives stable yield on sandy soil, but under low rainfall. This is the first study that highlighted the crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa, supporting their adaptability to climate change.

scholarly journals Scale-dependent tipping points of bacterial colonization resistance

2021 ◽  
Author(s):  
Yuya Karita ◽  
David T Limmer ◽  
Oskar Hallatschek
Keyword(s):  
Bacterial Colonization ◽  
Biophysical Model ◽  
Tipping Points ◽  
Colonization Resistance ◽  
Wide Range ◽  
Colonization Success ◽  
Dental Cavities ◽  
The Stability ◽  
Cell Motion ◽  
Stability And Resilience

Bacteria are efficient colonizers of a wide range of secluded micro-habitats, such as soil pores, skin follicles, dental cavities or crypts in gut-like environments. Although numerous factors promoting or obstructing stable colonization have been identified, we currently lack systematic approaches to explore how population stability and resilience depend on the scale of the micro-habitat. Using a microfluidic device to grow bacteria in crypt-like incubation chambers of systematically varied lengths, we found that the incubation scale can sensitively tune bacterial colonization success and resistance against invaders. Small crypts are un-colonizable, intermediately sized crypts can stably support dilute populations, while beyond a second critical lengthscale, populations phase-separate into a dilute and a jammed region. We demonstrate that the jammed state confers extreme colonization resistance, even if the resident strain is suppressed by an antibiotic. Combined with a flexible biophysical model, we show that scale acts as an environmental filter that can be tuned via the competition between growth and collective cell motion. More broadly, our observations underscore that scale can profoundly bias experimental outcomes in microbial ecology. Systematic, flow-adjustable lengthscale variations may serve as a promising strategy to elucidate further scale-sensitive tipping points and to rationally modulate the stability and resilience of microbial colonizers.

scholarly journals Relation between stability and resilience determines the performance of early warning signals under different environmental drivers

2015 ◽  
Vol 112 (32) ◽  
pp. 10056-10061 ◽  
Author(s):  
Lei Dai ◽  
Kirill S. Korolev ◽  
Jeff Gore
Keyword(s):  
Early Warning ◽  
Alternative Stable States ◽  
Basin Of Attraction ◽  
Environmental Drivers ◽  
Ecological Communities ◽  
Stable States ◽  
Warning Signals ◽  
Early Warning Signals ◽  
The Stability ◽  
Stability And Resilience

Shifting patterns of temporal fluctuations have been found to signal critical transitions in a variety of systems, from ecological communities to human physiology. However, failure of these early warning signals in some systems calls for a better understanding of their limitations. In particular, little is known about the generality of early warning signals in different deteriorating environments. In this study, we characterized how multiple environmental drivers influence the dynamics of laboratory yeast populations, which was previously shown to display alternative stable states [Dai et al., Science, 2012]. We observed that both the coefficient of variation and autocorrelation increased before population collapse in two slowly deteriorating environments, one with a rising death rate and the other one with decreasing nutrient availability. We compared the performance of early warning signals across multiple environments as “indicators for loss of resilience.” We find that the varying performance is determined by how a system responds to changes in a specific driver, which can be captured by a relation between stability (recovery rate) and resilience (size of the basin of attraction). Furthermore, we demonstrate that the positive correlation between stability and resilience, as the essential assumption of indicators based on critical slowing down, can break down in this system when multiple environmental drivers are changed simultaneously. Our results suggest that the stability–resilience relation needs to be better understood for the application of early warning signals in different scenarios.

scholarly journals Deciphering functional redundancy in the human microbiome

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Liang Tian ◽  
Xu-Wen Wang ◽  
Ang-Kun Wu ◽  
Yuhang Fan ◽  
Jonathan Friedman ◽  
...  
Keyword(s):  
Fecal Microbiota Transplantation ◽  
Human Microbiome ◽  
Functional Redundancy ◽  
Fecal Microbiota ◽  
Taxonomic Composition ◽  
Topological Features ◽  
Its Gene ◽  
The Stability ◽  
Stability And Resilience ◽  
Analyze Data

AbstractAlthough the taxonomic composition of the human microbiome varies tremendously across individuals, its gene composition or functional capacity is highly conserved — implying an ecological property known as functional redundancy. Such functional redundancy has been hypothesized to underlie the stability and resilience of the human microbiome, but this hypothesis has never been quantitatively tested. The origin of functional redundancy is still elusive. Here, we investigate the basis for functional redundancy in the human microbiome by analyzing its genomic content network — a bipartite graph that links microbes to the genes in their genomes. We find that this network exhibits several topological features that favor high functional redundancy. Furthermore, we develop a simple genome evolution model to generate genomic content network, finding that moderate selection pressure and high horizontal gene transfer rate are necessary to generate genomic content networks with key topological features that favor high functional redundancy. Finally, we analyze data from two published studies of fecal microbiota transplantation (FMT), finding that high functional redundancy of the recipient’s pre-FMT microbiota raises barriers to donor microbiota engraftment. This work elucidates the potential ecological and evolutionary processes that create and maintain functional redundancy in the human microbiome and contribute to its resilience.

Trophic structure within the Bristol Channel: seasonality and stability in Bridgwater Bay

1992 ◽  
Vol 72 (3) ◽  
pp. 675-690 ◽  
Author(s):  
P. A. Henderson ◽  
D. James ◽  
R. H. A. Holmes
Keyword(s):  
Trophic Structure ◽  
General Description ◽  
Dominant Animal ◽  
Estuarine Site ◽  
Overall Stability ◽  
Average Biomass ◽  
Using Data ◽  
The Stability ◽  
Stability And Resilience

A general description of the trophic inter-relationships and the food web within Bridgwater Bay, Somerset, England, is presented. This Bay is a lower estuarine site within the Bristol Channel. Particular attention is given to the use of the area by fish and larger crustaceans which are the dominant animal groups. Using data collected over a ten-year period of monthly sampling, the relative average biomass of all fish and larger crustaceans found within the Bay is calculated for each month of the year. These averages are used to produce food webs which also show species relative abundance for each calendar month.It is shown that the trophic structure follows a seasonal cycle due to migration. The application of the concept of stability within such a dynamic system is discussed. The role of compartmentalization of the ecosystem into a number of loosely connected groups as an aid to overall stability is discussed. While there is no evidence that contemporaneous compartments exist, it is argued that inter-specific interactions are temporally limited because of the different periods of annual residence of the species. It is suggested that the stability and resilience to interference shown by these estuarine systems is enhanced by temporal partitions.

BRICS, G20 and global economic governance reform

2021 ◽  
pp. 019251212110351 ◽  
Author(s):  
Marina Larionova ◽  
Andrey Shelepov
Keyword(s):  
Financial Regulation ◽  
Developing Economies ◽  
Economic Governance ◽  
Governance Reform ◽  
Financial Cooperation ◽  
Brics Countries ◽  
International Financial Architecture ◽  
The Stability ◽  
Stability And Resilience ◽  
Global Economic Governance

The article reviews cooperation between the BRICS countries (Brazil, Russia, India, China and South Africa) and their collective efforts to promote reform of international financial institutions, shape global financial regulation and improve financial cooperation. The authors focus on the BRICS–G20 engagement for global economic governance reform. To assess the progress so far, the study employs original quantitative data on the BRICS and G20 commitments and compliance, and qualitative analysis of the BRICS and G20 discourse and the transformation of the international economic architecture. The results suggest that, contrary to the common perception of the BRICS as a challenger of the traditional western-dominated international monetary and financial system, it acts in a cooperative manner, seeking to make the international financial architecture and global regulation more representative and responsive to emerging markets and developing economies needs, and strengthen the stability and resilience of international and domestic financial markets.

scholarly journals Geographical variation in the heterogeneity of mutualistic networks

2016 ◽  
Vol 3 (6) ◽  
pp. 150630 ◽  
Author(s):  
Shoko Sakai ◽  
Soeren Metelmann ◽  
Yukihiko Toquenaga ◽  
Arndt Telschow
Keyword(s):  
Seed Dispersal ◽  
Animal Species ◽  
Community Stability ◽  
Geographical Pattern ◽  
Strong Negative Correlation ◽  
Future Studies ◽  
Mutualistic Networks ◽  
The Stability ◽  
The Tropics ◽  
Stability And Resilience

Plant–animal mutualistic networks are characterized by highly heterogeneous degree distributions. The majority of species interact with few partner species, while a small number are highly connected to form network hubs that are proposed to play an important role in community stability. It has not been investigated, however, if or how the degree distributions vary among types of mutualisms or communities, or between plants and animals in the same network. Here, we evaluate the degree distributions of pollination and seed-dispersal networks, which are two major types of mutualistic networks that have often been discussed in parallel, using an index based on Pielou's evenness. Among 56 pollination networks we found strong negative correlation of the heterogeneity between plants and animals, and geographical shifts of network hubs from plants in temperate regions to animals in the tropics. For 28 seed-dispersal networks, by contrast, the correlation was positive, and there is no comparable geographical pattern. These results may be explained by evolution towards specialization in the presence of context-dependent costs that occur if plants share the animal species as interaction partner. How the identity of network hubs affects the stability and resilience of the community is an important question for future studies.

Future Scenarios

2020 ◽  
pp. 234-256
Author(s):  
Catherine E. De Vries ◽  
Sara B. Hobolt
Keyword(s):  
Political Change ◽  
Future Research ◽  
The Political ◽  
European Politics ◽  
Future Scenarios ◽  
Political Market ◽  
The Future ◽  
The Stability ◽  
Stability And Resilience ◽  
Normative Considerations

This chapter summarizes the main arguments and findings of the book by defining two key principles that guide political change in Europe. These two principles are the principle of contestability and the principle of appropriability. The principle of contestability focuses on the likelihood that a party can gain a larger share of the political market if it offers a product of greater value to voters. The principle of appropriability concerns the extent to which a successful innovator can capture the benefits resulting from its innovation. The chapter then outlines three different scenarios for the future of European politics. It also highlights topics which were not addressed in this book, but are nonetheless important areas for future research. Finally, the chapter discusses important normative considerations about the stability and resilience of democratic institutions.

Rethinking “Economic Fundamentals” in an Era of Global Physical Shocks: Insights from the Philippine Experience with COVID-19

2020 ◽  
pp. 1-45
Author(s):  
Toby Melissa C. Monsod ◽  
Maria Socorro Gochoco-Bautista
Keyword(s):  
Large Scale ◽  
The Philippines ◽  
Economic Outcomes ◽  
System Capacity ◽  
Gdp Growth ◽  
Economic Fundamentals ◽  
Laboratory Capacity ◽  
The Difference ◽  
The Stability ◽  
Stability And Resilience

Having “strong macroeconomic fundamentals”, as the Philippines supposedly did pre-COVID-19, matters much less (if at all), in and of itself, to economic outcomes in the context of a physical shock. Using a model for 21 countries in ASEAN + 3, developing East Asia and South Asia as well as Australia and New Zealand to explain the difference in actual 2019 and forecasted 2020 GDP growth, we find that, ceteris paribus, stronger national capacities to detect and respond to emerging outbreaks, in particular, laboratory capacity, are associated with better short term economic outcomes. For the Philippines, up to 3.6 percentage points in lost GDP growth forecasted in 2020 could have been saved. Our results suggest that a dearth in health system capacity should be prioritized over and above any other type of spending, including traditional stimulus (e.g. large-scale infrastructure) spending. Our results also underscore the need to rethink what is necessary for the stability and resilience of an economy – what are the “economic fundamentals” - in an era of global physical shocks, including those brought about by climate hazards. Given physical shocks, efficient and prepared government institutions matter. A macro economy is not resilient if these are not.

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