MaxEnt’s Parameter Configuration and Small Samples: Are We Paying Attention to Recommendations? A Systematic Review

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Description

Environmental niche modeling (ENM) is commonly used to develop probabilistic maps of species distribution. Among available ENM techniques, MaxEnt has become one of the most popular tools for modeling species distribution, with hundreds of peer-reviewed articles published each year. MaxEnt’s

Environmental niche modeling (ENM) is commonly used to develop probabilistic maps of species distribution. Among available ENM techniques, MaxEnt has become one of the most popular tools for modeling species distribution, with hundreds of peer-reviewed articles published each year. MaxEnt’s popularity is mainly due to the use of a graphical interface and automatic parameter configuration capabilities. However, recent studies have shown that using the default automatic configuration may not be always appropriate because it can produce non-optimal models; particularly when dealing with a small number of species presence points. Thus, the recommendation is to evaluate the best potential combination of parameters (feature classes and regularization multiplier) to select the most appropriate model. In this work we reviewed 244 articles published between 2013 and 2015 to assess whether researchers are following recommendations to avoid using the default parameter configuration when dealing with small sample sizes, or if they are using MaxEnt as a “black box tool.” Our results show that in only 16% of analyzed articles authors evaluated best feature classes, in 6.9% evaluated best regularization multipliers, and in a meager 3.7% evaluated simultaneously both parameters before producing the definitive distribution model. We analyzed 20 articles to quantify the potential differences in resulting outputs when using software default parameters instead of the alternative best model. Results from our analysis reveal important differences between the use of default parameters and the best model approach, especially in the total area identified as suitable for the assessed species and the specific areas that are identified as suitable by both modelling approaches. These results are worrying, because publications are potentially reporting over-complex or over-simplistic models that can undermine the applicability of their results. Of particular importance are studies used to inform policy making. Therefore, researchers, practitioners, reviewers and editors need to be very judicious when dealing with MaxEnt, particularly when the modelling process is based on small sample sizes.

Date Created
2017-03-14

Breaking Resilient Patterns of Inequality in Santiago de Chile: Challenges to Navigate Towards a More Sustainable City

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Description

Resilience can have desirable and undesirable consequences. Thus, resilience should not be viewed as a normative desirable goal, but as a descriptor of complex systems dynamics. From this perspective, we apply resilience thinking concepts to assess the dynamics of inequality,

Resilience can have desirable and undesirable consequences. Thus, resilience should not be viewed as a normative desirable goal, but as a descriptor of complex systems dynamics. From this perspective, we apply resilience thinking concepts to assess the dynamics of inequality, spatial segregation, and sustainability in Chile’s capital city of Santiago. Chile’s economy boosted since democracy was restored in 1990, but continuity of neoliberal reforms and transformations of Pinochet’s dictatorship (1973–1990) seem to have locked Chilean cities in resilient, albeit unsustainable, patterns of uneven development. Socio-economic data from Santiago shows highly resilient patterns of urban inequality and segregation from 1992 to 2009 despite democratic efforts, political agendas and discourses packed with calls for reducing poverty and inequality. We present a conceptual model based on the notion of stability landscapes to explore potential trade-offs between resilience and sustainable development. We mapped Santiago’s spatio-temporal inequality trends and explored if these patterns support an inequality-resilience stability landscape. Analysis of temporal and spatial distribution of development assets across four human development dimensions (i.e., income, education, health, democracy) revealed potential socio-political and spatial feedbacks supporting the resilience of inequality and segregation in Santiago. We argue that urban sustainability may require breaking this resilience, a process where bottom-up stressors such as social movements could play a key role.

Date Created
2016-08-19