scholarly journals Habitat loss-induced tipping points in metapopulations with facilitation

2018 ◽  
Author(s):  
Josep Sardanyés ◽  
Jordi Piñero ◽  
Ricard Solé
Keyword(s):  
Habitat Loss ◽  
Broad Class ◽  
Qualitative Change ◽  
Habitat Destruction ◽  
Tipping Points ◽  
Catastrophic Shift ◽  
Explicit Simulation ◽  
The Impact ◽  
Spatially Explicit Simulation Model ◽  
Spatial Patchiness

Habitat loss is known to pervade extinction thresholds in metapopulations. Such thresholds result from a loss of stability that can eventually lead to collapse. Several models have been developed to understand the nature of these transitions and how are they affected by the locality of interactions, fluctuations, or external drivers. Most models consider the impact of grazing or aridity as a control parameter that can trigger sudden shifts, once critical values are reached. Others explore instead the role played by habitat loss and fragmentation. Here we consider a minimal model incorporating facilitation along with habitat destruction, with the aim of understanding how local cooperation and habitat loss interact with each other. An explicit mathematical model is derived, along with a spatially explicit simulation model. It is found that a catastrophic shift is expected for increasing levels of habitat loss, but the breakpoint dynamics becomes continuous when dispersal is local. Under these conditions, spatial patchiness is found and the qualitative change from discontinuous to continuous results from a universal behaviour found in a broad class of nonlinear ecological systems (Weissmann and Shnerb, 2014; Martin et al. PNAS (2015) E1828-E1836). Our results suggest that species exhibiting facilitation and displaying short-range dispersal will be markedly more capable of dealing with habitat destruction, also avoiding catastrophic tipping points.

scholarly journals Habitat loss causes long transients in small trophic chains

2020 ◽  
Author(s):  
Blai Vidiella ◽  
Ernest Fontich ◽  
Sergi Valverde ◽  
Josep Sardanyés
Keyword(s):  
Habitat Loss ◽  
Habitat Destruction ◽  
Trophic Levels ◽  
Heteroclinic Bifurcation ◽  
Dynamical Study ◽  
Predator Species ◽  
Climate Conditions ◽  
Transient Phenomena ◽  
Saddle Node ◽  
The Impact

AbstractTransients in ecology are extremely important since they determine how equilibria are approached. The debate on the dynamic stability of ecosystems has been largely focused on equilibrium states. However, since ecosystems are constantly changing due to climate conditions or to perturbations such as the climate crisis or anthropogenic actions (habitat destruction, deforestation, or defaunation), it is important to study how dynamics can proceed till equilibria. In this contribution we investigate dynamics and transient phenomena in small food chains using mathematical models. We are interested in the impact of habitat loss in ecosystems with vegetation undergoing facilitation. We provide a thorough dynamical study of a small food chain system given by three trophic levels: vegetation, herbivores, and predators. The dynamics of the vegetation alone suffers a saddle-node bifurcation, causing extremely long transients. The addition of a herbivore introduces a remarkable number of new phenomena. Specifically, we show that, apart from the saddle node involving the extinction of the full system, a transcritical and a supercritical Hopf-Andronov bifurcation allow for the coexistence of vegetation and herbivores via non-oscillatory and oscillatory dynamics, respectively. Furthermore, a global transition given by a heteroclinic bifurcation is also shown to cause a full extinction. The addition of a predator species to the previous systems introduces further complexity and dynamics, also allowing for the coupling of different transient phenomena such as ghost transients and transient oscillations after the heteroclinic bifurcation. Our study shows how the increase of ecological complexity via addition of new trophic levels and their associated nonlinear interactions may modify dynamics, bifurcations, and transient phenomena.

scholarly journals Invasion in An Omnivorous Food Web: The Impact of Roles and Different Trophic Levels

2021 ◽  
Author(s):  
Duojie Jiabu ◽  
Weide Li
Keyword(s):  
Invasive Species ◽  
Food Web ◽  
Food Webs ◽  
Habitat Loss ◽  
Habitat Destruction ◽  
Trophic Levels ◽  
Theoretical Research ◽  
Model Framework ◽  
Habitat Loss And Fragmentation ◽  
The Impact

Abstract In the field of ecology, habitat loss and fragmentation are the two main characteristic forms of habitat destruction and the main drivers of species extinction, resulting in the gradual loss of biodiversity. So far, many scholars have made some progress in the theoretical research of the spatial food web, but research on the effect of introducing an invasive species in an omnivorous food web is very rare. In order to explore the impact of invader on the persistence of species in omnivorous food webs, we constructed a model framework to describe the patch occupation of each species in omnivorous systems. Our model results show that invasive species is a prey of species in omnivorous food webs is easier to invade than invasive species is a predator of species in original omnivorous food webs on habitat loss and fragmentation. One conclusion also can be drawn is that when an invasive species is a prey of species in omnivorous food webs, no matter what trophic level the invasive species is invade, it is more successful. But when invasive species is a predator of species in different trophic levels on omnivorous food webs, they show different coexistence patterns. The invasion of a species has little effect upon the stability of original omnivorous food web for habitat loss and fragmentation, and will only make the original omnivorous food web more stable and more complicated. Therefore, we have proved that the omnivorous food web is stable and is not easy to destroy this ecological fact. Some examples to illustrate the reliability of our model results are discussed.

scholarly journals The Implementation of Habitat Destruction Methods That Promote Native Survival Under Invasion

2021 ◽  
Author(s):  
Yinghui Yang ◽  
Haoqi Liu
Keyword(s):  
Native Species ◽  
Habitat Destruction ◽  
Indigenous Species ◽  
Promoting Effect ◽  
Term Survival ◽  
Long Term Survival ◽  
Explicit Simulation ◽  
Implementation Method ◽  
Spatially Explicit Simulation Model

Abstract Controlling invasive alien species invasion and maintaining the survival of native species have attracted increasing attention, and habitat destruction can be used to achieve these aims. However, it remains unclear whether and how to promote the long-term survival of indigenous species facing invaders through the use of habitat destruction. In this study, we developed a spatially explicit simulation model and exposed invaders and residents from this model to habitat destruction with different properties. The results showed that (1) introducing habitat destruction could promote the long-term survival of native species facing invaders; however, the promoting effect of habitat destruction occurred only over a period of time after introduction, and habitat destruction substantially weakened indigenous species before that. (2) Intermediate levels of habitat destruction were the most beneficial to the protection of native species. (3) Even if not considering the proportion of destroyed habitats, introducing spatially dispersed habitat destruction at an earlier time and shortening the interval between two habitat destruction events were very beneficial to the protection of residents. These insights can help facilitate the protection of residents under invasion by adjusting the implementation method of habitat destruction.

scholarly journals The Impact of Human Pressure and Climate Change on the Habitat Availability and Protection of Cypripedium (Orchidaceae) in Northeast China

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 84
Author(s):  
Huanchu Liu ◽  
Hans Jacquemyn ◽  
Xingyuan He ◽  
Wei Chen ◽  
Yanqing Huang ◽  
...  
Keyword(s):  
Climate Change ◽  
Northeast China ◽  
Habitat Destruction ◽  
Changbai Mountains ◽  
Suitable Habitat ◽  
Human Pressure ◽  
Terrestrial Orchids ◽  
The Future ◽  
Suitable Habitats ◽  
The Impact

Human pressure on the environment and climate change are two important factors contributing to species decline and overall loss of biodiversity. Orchids may be particularly vulnerable to human-induced losses of habitat and the pervasive impact of global climate change. In this study, we simulated the extent of the suitable habitat of three species of the terrestrial orchid genus Cypripedium in northeast China and assessed the impact of human pressure and climate change on the future distribution of these species. Cypripedium represents a genus of long-lived terrestrial orchids that contains several species with great ornamental value. Severe habitat destruction and overcollection have led to major population declines in recent decades. Our results showed that at present the most suitable habitats of the three species can be found in Da Xing’an Ling, Xiao Xing’an Ling and in the Changbai Mountains. Human activity was predicted to have the largest impact on species distributions in the Changbai Mountains. In addition, climate change was predicted to lead to a shift in distribution towards higher elevations and to an increased fragmentation of suitable habitats of the three investigated Cypripedium species in the study area. These results will be valuable for decision makers to identify areas that are likely to maintain viable Cypripedium populations in the future and to develop conservation strategies to protect the remaining populations of these enigmatic orchid species.

scholarly journals Does agricultural intensification cause tipping points in ecosystem services?

2021 ◽  
Author(s):  
Stephen C. L. Watson ◽  
Adrian C. Newton ◽  
Lucy E. Ridding ◽  
Paul M. Evans ◽  
Steven Brand ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Agricultural Intensification ◽  
Spatial Dynamics ◽  
Policy Option ◽  
List Type ◽  
Tipping Points ◽  
Software Models ◽  
Non Linear ◽  
Study Interval ◽  
The Impact

Abstract Context Agricultural intensification is being widely pursued as a policy option to improve food security and human development. Yet, there is a need to understand the impact of agricultural intensification on the provision of multiple ecosystem services, and to evaluate the possible occurrence of tipping points. Objectives To quantify and assess the long-term spatial dynamics of ecosystem service (ES) provision in a landscape undergoing agricultural intensification at four time points 1930, 1950, 1980 and 2015. Determine if thresholds or tipping points in ES provision may have occurred and if there are any detectable impacts on economic development and employment. Methods We used the InVEST suite of software models together with a time series of historical land cover maps and an Input–Output model to evaluate these dynamics over an 85-year period in the county of Dorset, southern England. Results Results indicated that trends in ES were often non-linear, highlighting the potential for abrupt changes in ES provision to occur in response to slight changes in underlying drivers. Despite the fluctuations in provision of different ES, overall economic activity increased almost linearly during the study interval, in line with the increase in agricultural productivity. Conclusions Such non-linear thresholds in ES will need to be avoided in the future by approaches aiming to deliver sustainable agricultural intensification. A number of positive feedback mechanisms are identified that suggest these thresholds could be considered as tipping points. However, further research into these feedbacks is required to fully determine the occurrence of tipping points in agricultural systems.

scholarly journals Fishery Audit 2019

2019 ◽  
Author(s):  
Oceana ◽  
Devan Archibald ◽  
Robert Rangeley
Keyword(s):  
Federal Government ◽  
Habitat Destruction ◽  
Fish Populations ◽  
Fish Stock ◽  
Strong Base ◽  
Research Survey ◽  
The Government ◽  
Auditor General ◽  
The Impact ◽  
Fisheries Act

Healthy fish populations are critical to healthy ecosystems: they feed communities, support economies and are essential to our survival. But our oceans are facing growing threats and greater uncertainty. Overfishing, climate change, habitat destruction and pollution are degrading the underwater world and putting the marine life we all depend upon at risk. Much is at stake, as the status quo is demonstrably not working. The number of stocks in the healthy zone has decreased since Oceana Canada released its 2018 Fishery Audit, and the number in the critical zone has increased — including crab and shrimp stocks. This isparticularly worrying if the depletion of crustaceans becomes a trend, as the value of Canada’s seafood industry depends heavily on them. Progress on implementing rebuilding plans remains slow and many critically depleted stocks, including northern cod, are still without a plan. As well, Fisheries and Oceans Canada (DFO) has not yet indicated how and by when it will collect adequate catch monitoring information, needed to measure and manage bycatch (the incidental catch of non-target fish) in all Canadian commercial fisheries. Meanwhile, only two of the 11 recommendations from the 2018 Fishery Audit have been implemented. DFO has made some progress since the last Fishery Audit was released. In 2019, DFO published more information to help assess fish stock health, and some elements of fishery monitoring became more transparent. DFO also implemented some of the recommendations from the 2016 Auditor General report on sustainable fisheries, including developing timelines and priorities for rebuilding plans for depleted fish populations. Most importantly, a modernized Fisheries Act became law in June 2019. For the first time in the Act’s history, rebuilding plans are now required for depleted fish populations. The government has committed more than $100 million over five years to assess and rebuild fish stocks. This brings Canada into the group of nations with modern fisheries laws and could signal a historic turning point in the health of Canadian fisheries. The impact of the new Act will depend on the strength and pace of regulations, currently under development. The regulations will outline what rebuilding plans must include, and Oceana Canada is advocating that, at a minimum, they should specify a timeline and target, aimed at rebuilding stocks to healthy levels. In the year ahead, the federal government must develop strong and effective regulations to support the rebuilding provisions in the Fisheries Act and accelerate the implementation and enforcement of existing policies. Fortunately, there is a strong base of support for new regulations to rebuild stocks, new funding commitments and much-needed increases in DFO’s science capacity to get the job done. We have the tools needed to modernize Canada’s approach to fisheries management and rebuild fish populations, and Canadians want to see this happen. In a recent Abacus Data market research survey, 98 per cent of Canadians said it was important that the federal government work to rebuild abundant fish populations. If the government fails to take these actions, we can expect the number of healthy stocks to continue to decline and depleted populations will fail to recover, impoverishing the oceans and the coastal communities who depend on them.

scholarly journals Grassland-to-crop conversion in agricultural landscapes has lasting impact on the trait diversity of bees

2020 ◽  
Author(s):  
Gaëtane Le Provost ◽  
Isabelle Badenhausser ◽  
Cyrille Violle ◽  
Fabrice Requier ◽  
Marie D’Ottavio ◽  
...  
Keyword(s):  
Land Use ◽  
Habitat Loss ◽  
Agricultural Landscapes ◽  
Habitat Destruction ◽  
Land Use History ◽  
Pollinator Decline ◽  
Plant Trait ◽  
Trait Diversity ◽  
Bee Communities ◽  
Over Time

Abstract Context Global pollinator decline has motivated much research to understand the underlying mechanisms. Among the multiple pressures threatening pollinators, habitat loss has been suggested as a key-contributing factor. While habitat destruction is often associated with immediate negative impacts, pollinators can also exhibit delayed responses over time. Objectives We used a trait-based approach to investigate how past and current land use at both local and landscape levels impact plant and wild bee communities in grasslands through a functional lens. Methods We measured flower and bee morphological traits that mediate plant–bee trophic linkage in 66 grasslands. Using an extensive database of 20 years of land-use records, we tested the legacy effects of the landscape-level conversion of grassland to crop on flower and bee trait diversity. Results Land-use history was a strong driver of flower and bee trait diversity in grasslands. Particularly, bee trait diversity was lower in landscapes where much of the land was converted from grassland to crop long ago. Bee trait diversity was also strongly driven by plant trait diversity computed with flower traits. However, this relationship was not observed in landscapes with a long history of grassland-to-crop conversion. The effects of land-use history on bee communities were as strong as those of current land use, such as grassland or mass-flowering crop cover in the landscape. Conclusions Habitat loss that occurred long ago in agricultural landscapes alters the relationship between plants and bees over time. The retention of permanent grassland sanctuaries within intensive agricultural landscapes can offset bee decline.

Variance Regularization in Sequential Bayesian Optimization

2020 ◽  
Vol 45 (3) ◽  
pp. 966-992
Author(s):  
Michael Jong Kim
Keyword(s):  
Error Bounds ◽  
Broad Class ◽  
Planning Horizon ◽  
Bayesian Optimization ◽  
Model Parameters ◽  
Regularization Term ◽  
Problem Class ◽  
Special Cases ◽  
The Impact ◽  
Bayesian Dynamic Programming

Sequential Bayesian optimization constitutes an important and broad class of problems where model parameters are not known a priori but need to be learned over time using Bayesian updating. It is known that the solution to these problems can in principle be obtained by solving the Bayesian dynamic programming (BDP) equation. Although the BDP equation can be solved in certain special cases (for example, when posteriors have low-dimensional representations), solving this equation in general is computationally intractable and remains an open problem. A second unresolved issue with the BDP equation lies in its (rather generic) interpretation. Beyond the standard narrative of balancing immediate versus future costs—an interpretation common to all dynamic programs with or without learning—the BDP equation does not provide much insight into the underlying mechanism by which sequential Bayesian optimization trades off between learning (exploration) and optimization (exploitation), the distinguishing feature of this problem class. The goal of this paper is to develop good approximations (with error bounds) to the BDP equation that help address the issues of computation and interpretation. To this end, we show how the BDP equation can be represented as a tractable single-stage optimization problem that trades off between a myopic term and a “variance regularization” term that measures the total solution variability over the remaining planning horizon. Intuitively, the myopic term can be regarded as a pure exploitation objective that ignores the impact of future learning, whereas the variance regularization term captures a pure exploration objective that only puts value on solutions that resolve statistical uncertainty. We develop quantitative error bounds for this representation and prove that the error tends to zero like o(n-1) almost surely in the number of stages n, which as a corollary, establishes strong consistency of the approximate solution.

scholarly journals Quantifying the impact of vegetation‐based metrics on species persistence when choosing offsets for habitat destruction

2020 ◽  
Author(s):  
Erica Marshall ◽  
Roozbeh Valavi ◽  
Louise O’ Connor ◽  
Natasha Cadenhead ◽  
Darren Southwell ◽  
...  
Keyword(s):  
Habitat Destruction ◽  
Species Persistence ◽  
The Impact
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