New methods for incorporating connectivity into evaluating the human footprint

The impact of human activities on the landscape is often quantified by spatial human footprint indexes (SHFI). However, few studies have evaluated the effect of the human footprint on landscape connectivity, which can be useful and more realistic for conservation planning.  To better evaluate the effect of the human footprint on connectivity, human footprint measures can be supplemented by integrating variables of habitat loss and fragmentation, and by making them explicit either for individual species or with a multi-species approach.

geographic_map_of_mexicoIn our recent paper, we modified the SHFI proposed by Etter et al. (2011), which integrates three components: land use intensity, time of human landscape intervention, and biophysical vulnerability.  We adjusted the original index by the addition of a new component representing habitat loss and fragmentation. This adjusted SHFI was applied to remnant habitat for 40 terrestrial mammal species representative of the Trans-Mexican Volcanic System in western-central Mexico, which stretches over 160,000 km2 and is recognized as the most heterogeneous biogeographic province in Mexico in terms of its geological and biotic history.  This area is also one of the ecoregions in Mexico with the highest anthropic impact, with high agricultural production, high geographic accessibility, and high population density.

In addition, we constructed three multi-species scenarios and one all-species-inclusive scenario to assess the differences in human footprint on multi-species connectivity approach. We grouped terrestrial mammal species according to their requirements of dispersal distance and minimum habitat area. Using the SHFI as a dispersal resistance surface and applying a circuit theory based approach, we analyzed the effects of cumulative human impact on habitat connectivity in the different scenarios.  Finally, we evaluated the degree of spatial overlap between all pairs of human footprints maps and all pairs of current flow maps.

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Our results showed that the effect of human impact on connectivity is higher for species with limited dispersal capacity (100–500 m), making them more susceptible to eventual future increments of habitat loss and fragmentation.  In contrast, species with intermediate dispersal thresholds (500-1500 m) are less susceptible to such impacts.  A majority of the area (> 62%) of all habitat scenarios used was dominated by high values of human footprint (SHFI > 60).  This research represents a significant advance in the evaluation of the magnitude of the human impact on connectivity.  It can show which groups of species are more sensitive to the spatial human footprint for conservation protocols, and establish similarities in impact on the habitat of species with different ecological characteristics.

Resources

Correa Ayram, C. A., M. E. Mendoza, A. Etter, and D. R. Pérez Salicrup. 2017. Anthropogenic impact on habitat connectivity: a multidimensional human footprint index evaluated in a highly biodiverse landscape of Mexico. Ecological Indicators 72: 895-909.

Etter, A., C. A. McAlpine, L. Seabrook, and K. A. Wilson. 2011. Incorporating temporality and biophysical vulnerability to quantify the human spatial footprint on ecosystems. Biological Conservation 144(5): 1585-1594.

2017-03-19T23:30:00+00:00 September 30th, 2016|

About the Author:

Camilo Correa

Camilo Correa received his bachelor’s degree in Ecology from the Pontificia Universidad Javeriana of Bogotá, Colombia and is a PhD candidate in Environmental Geography at the Centro de Investigaciones en Geografía Ambiental at the Universidad Nacional Autónoma de México. He also received a master’s degree in Geography (orientation in Integrated Landscape Management) from the same university. His dissertation focuses on the integration of landscape connectivity models in spatial conservation planning in a highly biodiverse landscape of Mexico. He is also interested in evaluating human spatial footptrint on ecological process at the landscape level and the effects of climate change and land use/cover change on habitat connectivity.