SMB2020 subgroup Poster Prize: Vitor Sudbrack

Congratulations to Vitor Sudbrack, one of the 4 winners of the SMB2020 PDEE poster prizes!

View the prizewinning poster here

What is the ecological value of fragmented landscapes?

Imagine the following situation: you are contacted by local authorities to ask your recommendation on two possibilities of ecological reserve parks. The first possibility is a huge park with a total area of 3 km² - almost a new Central Park. The second proposal is constructing three smaller parks, 1 km² each, and therefore summing the same total area as before. After suggesting that both actions should be considered simultaneously and hearing a negative feedback from them, which possibility would you endorse? What further information would you request in order to make your choice?

Well, if you experienced the ecological debates from the 70’s, this scenario might remind you of the question: single large or several small?. This simple question, abbreviated by SLOSS, has evolved for almost half a century and the answer is, up to this day, very arguable ¹². Perhaps, one of the most important progresses of this question was to change it from a binary point of view - i.e. compact versus fragmented - to a continuous problem, investigating the effect of the degree of fragmentation to the ecological value of landscapes. It is also important to distinguish between fragmentation and the fragmentation process. This latter occurs simultaneously with habitat loss and, therefore, is always detrimental to ecosystems. To make this distinction even clearer, we refer to the difference of spatial configuration while keeping the total habitat amount constant as fragmentation per se ³.

Since there are no two regions differing purely by spatial configuration, statistical techniques must be applied to observational data in order to isolate the effects of fragmentation per se on abundance, richness, evenness, or other metrics of ecological value ⁴. And this point is exactly where we believe that computational techniques may be a powerful tool to help researchers to test hypotheses, mechanisms and concepts and even generate controlled artificial data in order to analyse the suitability of statistical techniques.

In this project we propose to explore a population density model of two partial differential equations in binary landscapes, i.e. landscapes composed of regions of either habitat or matrix (non-habitat). Considering mechanisms of diffusive movement of individuals on the entire landscape and two distinct reactions - logistic growth in habitat and death in matrix, - we concluded that fragmentation per se may have positive effects to the abundance of populations given that the matrix is soft, i.e it allows individuals to penetrate reasonable distances. In this case, movement between habitat regions (patches) through the matrix is possible and causes a relaxation of the intraspecific competition within patches, leading to higher abundances of species distributed over a larger area. In the opposite case of a very hostile matrix, habitat patches are disconnected, making it necessary to individually have enough area to support population settlement. Then, landscape fragmentation is detrimental and it can even lead to extinction of species.

We hope our work shifts the paradigm of either fragmentation per se is good or bad to ecological metrics to a less universal perspective, i.e. acknowledging that effects may occur in both directions and with different magnitudes, understanding that each case depends on further information of the system, as the quality of matrix quantified in our model.

About the experience in eSMB2020

We were immensely happy to have the opportunity of exposing our project in a meeting of incredible researchers from all over the world working in Mathematical Biology, and more specifically our subgroup of Population Dynamics, Ecology and Evolution. The feedback, networking and information exchange environment in eSMB2020 was awesome and overcame any possible adversity which an online version could have had compared to traditional conferences. Understanding the new opportunities that the virtual world brings is key and we tried to bring it into our presentation: virtual posters make linking supplementary material, documents and contact information much easier than traditional versions - only one click away from viewers. The platforms selected by the organizers made the poster presentations easy, interactive and reserved, which immensely contributed to the success of the event. Finally, we take the opportunity to thank all organizers, session chairs, lectures and hosts, the support team and every colleague of the Mathematical Biology community present.

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