Landscape connectivity

En este estudio se aplicó un método de reconocimiento de la estructura del paisaje basado en el procesamiento morfológico de imágenes, con el fin de analizar el cambio multitemporal en los fragmentos de hábitat de la cuenca del lago Cuitzeo. Dicha área presenta una gran importancia ecológica para la región, sin embargo, sus coberturas arbóreas y arbustivas han sido drásticamente transformadas a través del tiempo. Como base cartográfica para el modelamiento espacial se utilizaron los mapas de cobertura de los años 1975,1996, 2000, 2003 y 2008. Se identificaron los fragmentos de hábitat con base en modelos de aptitud de hábitat de dos especies focales, se llevó a cabo la clasificación morfológica para cada año de estudio y se realizó el análisis comparativo haciendo énfasis en la conectividad del paisaje. Los fragmentos de hábitat grandes (>200 ha) decrecieron considerablemente en los años más recientes. Por el contrario, en dicho periodo las áreas de los elementos conectores del paisaje se recuperaron. La aplicación del enfoque de análisis morfológico demostró ser una herramienta útil en el monitoreo de los procesos de fragmentación y pérdida de hábitat.

Marine reserves are widely used to protect species important for conservation and fisheries and to help maintain ecological processes that sustain their populations, including recruitment and dispersal. Achieving these goals requires well-connected networks of marine reserves that maximize larval connectivity, thus allowing exchanges between populations and recolonization after local disturbances. However, global warming can disrupt connectivity by shortening potential dispersal pathways through changes in larval physiology. These changes can compromise the performance of marine reserve networks, thus requiring adjusting their design to account for ocean warming. To date, empirical approaches to marine prioritization have not considered larval connectivity as affected by global warming. Here, we develop a framework for designing marine reserve networks that integrates graph theory and changes in larval connectivity due to potential reductions in planktonic larval duration (PLD) associated with ocean warming, given current socioeconomic constraints. Using the Gulf of California as case study, we assess the benefits and costs of adjusting networks to account for connectivity, with and without ocean warming. We compare reserve networks designed to achieve representation of species and ecosystems with networks designed to also maximize connectivity under current and future ocean-warming scenarios. Our results indicate that current larval connectivity could be reduced significantly under ocean warming because of shortened PLDs. Given the potential changes in connectivity, we show that our graph-theoretical approach based on centrality (eigenvector and distance-weighted fragmentation) of habitat patches can help design better-connected marine reserve networks for the future with equivalent costs. We found that maintaining dispersal connectivity incidentally through representation-only reserve design is unlikely, particularly in regions with strong asymmetric patterns of dispersal connectivity. Our results support previous studies suggesting that, given potential reductions in PLD due to ocean warming, future marine reserve networks would require more and/or larger reserves in closer proximity to maintain larval connectivity.

In this work, we analyzed the temporal trends of nine selected key terms used in the habitat fragmentation arena, quantifying their number (and frequency) of recurrence on Web of Science from 1960 to 2020. The most used key (focal) terms ("stepping stones", "habitat corridors", "landscape connectivity"), showed a progressive increase from 1981 to 2020, with "landscape connectivity" showing the highest increase in frequency in the last decade (2011-2020). Among the key secondary terms (recurring < 5%), although "corridors", "continuity", and "contiguity" showed a slight growth over the decades, "connectivity conservation" showed the most significant increase. This last landscape-related term recently replaced other local-scale concepts (as "stepping stones" and "corridors") as a consequence of a change of perspective. Conversely, "ecological network planning", used in landscape planning and less in conservation biology, showed a comparable fewer recurrence. This gap in recurrences could be due to a bias in our research approach, as Web of Science is a search engine that does not intercept grey literature (as plans and reports) drawn up by Public Agencies which rarely appears in scientific journals.