Research Article |
Corresponding author: Matthew D. Moran ( moran@hendrix.edu ) Academic editor: Jochen A.G. Jaeger
© 2019 Matthew D. Moran, Allison Monroe, Lindsay Stallcup.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Moran MD, Monroe A, Stallcup L (2019) A proposal for practical and effective biological corridors to connect protected areas in northwest Costa Rica. Nature Conservation 36: 113-137. https://doi.org/10.3897/natureconservation.36.27430
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Habitat loss and increases in habitat isolation are causing animal population reductions and extirpations in forested areas of the world. This problem extends to protected areas, which, while often well-conserved, can be too small and isolated to maintain species that exist at low densities and require large contiguous areas of habitat (e.g. some large mammals). Costa Rica has been at the forefront of tropical forest conservation and a large proportion of the country’s land area is currently under some form of protection. One such area is the northwest portion of Costa Rica, which is an extremely biodiverse region with several noteworthy national and privately-owned protected areas. However, each protected area is an isolated island in a sea of deforestation. Within Costa Rica’s existing framework of biological corridors, we propose four sub-corridors as targets for restoration and full protection. These sub-corridors would link five major protected areas in northwest Costa Rica, with all of them linking to larger protected areas in the central portion of the country, while impacting a small number of people who reside within the corridors. After natural or active reforestation of the corridors, the result would be a contiguous protected area of 348,000 ha. The proposed sub-corridors would represent a 3.7% increase in protected area size in the region and only 0.2% of Costa Rica’s total land area. Using the jaguar (Panthera onca) as a model umbrella species, we estimated that each current isolated protected area could support between 8–104 individuals. Assuming lack of dispersal between protected areas (distance between each ranges from 8.1 to 24.9 km), these population sizes are unlikely to be viable in the long term. However, the combined protected areas, connected by biological sub-corridors, could support about 250 jaguars, a population size with a higher probability of surviving. Our study shows that focusing conservation efforts on a relatively small area of Costa Rica could create a large protected area derived from numerous small isolated preserves.
biological corridors, conservation, Costa Rica, Panthera onca, protected areas
Biological corridors are important conservation tools for maintaining species diversity in places where habitat loss results in small isolated areas of natural landscapes (
Tropical rainforests continue to undergo rapid deforestation and fragmentation in many parts of the world (
The Mesoamerican Biological Corridor proposal would connect a series of large existing protected areas via biological corridors, allowing connectivity from southern Mexico to Panama (
Proposed biological sub-corridors within the protected land and Costa Rican government designated biological corridors in north-western Costa Rica. A Guanacaste – Miravalles B Miravalles – Tenorio C Tenorio – Monteverde-Arenal Bioregion D Monteverde-Arenal Bioregion – Central Volcanic Mountain Range, 1 = Arenal – Tenorio Biological Corridor (SINAC-designated), 2 = Paso Las Nubes Biological Corridor (SINAC-designated).
The north-western part of Costa Rica includes several noteworthy state- and privately-owned biological preserves such as Santa Rosa NP, Guanacaste NP, Rincón de la Vieja NP, Arenal NP, Monteverde Cloud Forest Reserve and the Children’s Eternal Rainforest. The area is characterised by low elevation terrain punctuated by a series of young volcanic ranges. Habitat diversity is extremely high and includes tropical dry forests, pre-montane forests, cloud forests and tropical wet forests. Currently, protected areas are concentrated in the major volcanic features of the Guanacaste and Tilarán mountain ranges, plus a large area of tropical dry forest (Santa Rosa and Guanacaste National Parks) that stretches to the Pacific Ocean. With the exception of connectivity in the Guanacaste region, where three large national parks are connected either directly (Santa Rosa and Guanacaste) or by a protected corridor (Guanacaste and Rincón de la Vieja), protected areas are relatively small and isolated. For example, the Monteverde-Arenal Bioregion (MAB) is described as connected to its nearest neighbours, Tenorio National Park to the west and Juan Castro Blanco National park to the east, via SINAC’s Arenal-Tenorio and Paso Las Nubes Biological Corridors, respectively. On the ground, however, functional connectivity (in terms of ability of forest-dependent organisms to move through these corridors) is less than ideal since the two biological corridors in question are composed mostly of fragments (see results) of forest with little or no formal protection. Recent monitoring of fragmented lands surrounding the MAB indicates that many large mammals found in the parks and preserves are not utilising their habitat outside the protected areas (
The distance between the isolated protected areas in the north-western part of Costa Rica is relatively small (minimum: 8km, maximum: 25 km) and there are areas of natural forest cover (variety of primary and secondary growth, M. Moran and L. Stallcup, personal observation) between these protected areas. Human population density is also relatively low, making for a high potential for creating biological corridors with low impact on human communities.
The goal of this study was to determine if we could identify potential sub-corridors within the larger SINCAC biological corridors that would have parameters that allow for the movement of forest-dependent species. These sub-corridors would meet the minimum size requirement (defined here as having a minimum width of 1000 m,
We downloaded boundaries of legally protected terrestrial lands (
We then obtained recent satellite views for each of the proposed sub-corridors from Google Earth Pro™. All corridor locations had satellite imagery from the year 2017. We established that the minimum width of any point along the corridor must be at least 1000 m, since this width appears to allow movement of practically all non-flying mammals in the Neotropics (
Satellite views of the four proposed biological sub-corridors (in yellow) with adjoining protected areas (in red). Dark green areas indicate the presence of forested habitat.
We then modelled the potential population size of jaguars, a commonly utilised “umbrella” species, whose presence may indicate a well-functioning ecosystem (
Our analysis has limitations worth considering. Except for forest cover proportion, we did not utilise computer software (e.g. Marxan) to choose the best path for our sub-corridors. Instead, once we had located a pathway with the most forest cover that did not cross towns and other settlements, we made individual decisions on corridor shape and path based on local land use, shape of forest blocks, human structures, distance between existing protected areas and existing political frameworks (e.g. existence of current SINAC corridor designations). Our analysis, therefore, does not take into account costs, biodiversity protection or boundary length, as would be incorporated into some programmes (
The four proposed biological sub-corridors in northwest Costa Rica (Fig.
Current physical characteristics of proposed biological sub-corridors in northwest Costa Rica that would produce a contiguous protected area from the Guanacaste Region (Santa Rosa NP) to the Central Volcanic Mountain Range. *indicates area covered in recent volcanic activity with sparse, but natural vegetation. †indicates barren land caused by ongoing road construction.
Corridor | Area (Ha) | Proportion forested | Proportion pasture | Proportion developed | Proportion Other | Length (km) | Human structures |
---|---|---|---|---|---|---|---|
Guanacaste–Miravalles | 1,594 | 0.481 | 0.500 | 0.004 | 0.015* | 8.2 | 28 |
Miravalles–Tenorio | 2,532 | 0.715 | 0.227 | <0.001 | 0.058* | 9.7 | 0 |
Tenorio–MAB | 3,946 | 0.674 | 0.326 | <0.001 | 0.000 | 18.6 | 12 |
MAB–CVMT | 4,277 | 0.765 | 0.224 | 0.004 | 0.007† | 24.9 | 19 |
Total Corridor Area | 12,349 | ||||||
Current Protected Area | 348,000 |
Area covered by all proposed corridors, currently protected lands and proportional contributions of these lands relative to current protected areas and Costa Rica as a whole.
Total corridor area (Ha) | Proportion addition to protected areas (region) | Proportion of Costa Rica |
---|---|---|
12,349 | 0.037 | 0.002 |
Details of land use for each proposed sub-corridor. A Guanacaste – Miravalles B Miravalles – Tenorio C Tenorio – Monteverde-Arenal Bioregion D Monteverde-Arenal Bioregion – Central Volcanic Mountain Range.
The sub-corridor we propose to connect the Guanacaste complex (specifically Rincón de la Vieja National Park) to Miravalles National Park, Sub-corridor A, has the most deforested lands and contains the greatest number of human-built structures (Fig.
The 23 studies that sampled jaguar density in tropical forests of Central America found an average of 7.09 jaguars/100 km2 ± 1.16 (2SE, Appendix
Estimated population sizes of jaguar (Panthera onca) that could be supported in 1current contiguous protected areas, 2proposed contiguous protected areas connected by biological sub-corridors and habitat areas for each location. GC = Guanacaste Complex, M = Miravalles, T = Tenorio, MAB = Monteverde-Arenal Bioregion, CVMR = Central Volcanic Mountain Range, NWCR = Northwest Costa Rica including GC, M, T, MAB and three proposed corridors (Table
Estimate | GC1 | M1 | T1 | MAB 1 | CVMR 1 | NWCR 2 | NWCR & CVMR2 |
---|---|---|---|---|---|---|---|
Mean | 78 | 8 | 13 | 34 | 104 | 145 | 252 |
Low | 60 | 6 | 10 | 27 | 80 | 112 | 195 |
High | 96 | 10 | 16 | 42 | 128 | 179 | 310 |
Habitat Area (Ha) | 110,241 | 11,670 | 18,492 | 48,500 | 146,794 | 196,975 | 348,049 |
The four functional sub-corridors proposed in this paper (Fig.
This proposed sub-corridor is the smallest and shortest, connecting the relatively large, biodiverse and contiguous reserves of the Guanacaste region (Santa Rosa, Guanacaste and Rincon de la Vieja National Parks) to Miravalles National Park. Presumably, this corridor would increase species richness in the latter since it would connect it to a much larger complex of conserved areas. However, Sub-corridor A also has the lowest level of forest cover (slightly less than 50%) and the greatest number of human structures, including some small developed areas, presumably containing a considerable number of people (Fig.
This proposed sub-corridor, which connects Miravalles and Tenorio National Parks, is moderate in size and length, but it is probably the most practical under current land-use conditions. It is more than 75% forested and contains no human dwellings. The only development is a road (Route 6) that passes through the area. While this sub-corridor would be relatively easy to establish (if landowners were willing), it would only connect two relatively small protected areas, Miravalles and Tenorio National Parks. If neither of these conservation areas were connected via biological corridors to other regions, the conservation value, in terms of connecting populations of species that require large habitat areas, would presumably be modest.
This proposed sub-corridor connects Tenorio with the Monteverde-Arenal Bioregion (MAB). It is relatively large, traverses a long distance, is about two-thirds forested and has relatively few human structures, most of which are located along Route 142 between Lake Arenal and the town of La Fortuna. Many of these developments are associated with ecotourism (Fig.
This proposed sub-corridor connecting the MAB to the Central Volcanic Mountain Range has perhaps the highest conservation potential, but is challenging biologically (because of length,
The areas proposed for conservation in this study are very small relative to the size of Costa Rica and less than 5% the size of the current protected areas in the region (stretching from northwest Costa Rica to the Central Volcanic Mountain Range). In addition, the majority of the areas where sub-corridors are proposed already have relatively high proportions of forest cover and would therefore require a small amount of restoration work, such as active native tree planting. Other small corridors in the process of being established in Costa Rica also share these characteristics (
One strategy could be the incorporation of these sub-corridors into existing protected areas. All proposed biological corridors would connect directly to existing parks and preserves owned by the Costa Rican government. While requiring additional public resources for purchase and protection, this method would work within the existing framework on land protection. In contrast to direct purchase of land for inclusion into the national system of protected areas, one could consider more creative land conservation methods. For example, targeted ecosystem service payments and/or conservation easements for high priority lands could be employed to promote connectivity in and around the proposed sub-corridors. Costa Rica’s current system of environmental service payments, which include carbon emissions offsets, watershed protection, biodiversity maintenance and scenic and recreational enhancement (
The current protected areas of northwest Costa Rica are each too small to provide long-term survival to some species, such as the jaguar. While jaguars are present in the region (
Thanks to B. Hill who assisted with Arc GIS procedures. D. Hamilton, Y. Rodríguez Santamaría and H. Villalobos Sánchez provided valuable feedback with respect to Costa Rica’s current system of biological corridors. C. Chetkiewicz and J. Jaeger provided valuable comments on an earlier version of the manuscript.
Data Description | Source | Link | Year |
---|---|---|---|
Protected areas of Costa Rica | Protected Planet | https://www.protectedplanet.net/country/CR | 2017 |
Biological Corridors of Costa Rica | Sistema Nacional de Áreas de Conservación de Costa Rica (SINAC) | http://www.onfcr.org/psa/capas-de-prioridades | 2016 |
Forest Cover | Global Forest Watch | https://beta-gfw.opendata.arcgis.com/items/7876b225f8034a0ebba79fad4afb80ad | 2017 |
Human Population Estimates | Center for International Earth Science Information Network | http://beta.sedac.ciesin.columbia.edu/data/set/gpw-v4-population-density/data-download | 2015 |
Administrative Roads of Costa Rica | MapCruzin | https://mapcruzin.com/free-costa-rica-country-city-place-gis-shapefiles.htm | 2018 |
Costa Rica and Nicaragua Boundaries | Diva-GIS | http://www.diva-gis.org/datadown | 2001 |
Literature cited (Appendix
Data sources for the estimation of jaguar (Panthera onca) densities in Central American habitats.
Density (N/100 km2) | Habitat | Location | Source |
---|---|---|---|
8.80 | Moist Tropical Rainforest | Cockscomb, Belize | Silver 2004 |
7.48 | Moist Tropical Rainforest | Chiquibul, Belize | Silver 2004 |
5.40 | Tropical Dry Forest | Jalisco, Mexico | Núñez‐Pérez 2011 |
8.80 | Moist Tropical Rainforest | Cockscomb, Belize | Harmsen 2006 |
4.82 | Moist Tropical Rainforest | Cockscomb, Belize | Harmsen 2006 |
18.29 | Moist Tropical Rainforest | Cockscomb, Belize | Harmsen 2006 |
11.45 | Moist Tropical Rainforest | Cockscomb, Belize | Harmsen 2006 |
5.30 | Tropical Dry Forest | Fireburn, Belize | Miller 2005 |
11.28 | Moist Tropical Rainforest | Gallon Jug, Belize | Miller 2005 |
8.82 | Moist Tropical Rainforest | Gallon Jug, Belize | Miller 2006 |
6.98 | Moist Tropical Rainforest | Corcovado, Costa Rica | Salom-Pérez et al. 2007 |
2.00 | Moist Tropical Rainforest | Golfo Dulce, Costa Rica | Bustamante 2008 |
6.70 | Moist Tropical Rainforest | Guanacaste, Costa Rica | Rojas 2006 |
1.34 | Moist Tropical Rainforest | Talamanca, Costa Rica | Gutierrez and Porras 2008 |
5.42 | Moist Tropical Rainforest | Talamanca, Costa Rica | González-Maya 2007 |
11.28 | Moist Tropical Rainforest | Carmelita, Guatemala | Moreira et al. 2008a |
1.54 | Moist Tropical Rainforest | La Gloria, Guatemala | Moreira et al. 2007 |
1.99 | Moist Tropical Rainforest | Mirador, Guatemala | Moreira et al. 2005 |
11.14 | Moist Tropical Rainforest | Dos Lagunas, Guatemala | Moreira et al. 2008b |
6.63 | Moist Tropical Rainforest | Tikal, Guatemala | García et al. 2006 |
6.04 | Moist Tropical Rainforest | Mechor de Mecos, Guatemala | Moreira et al. 2010 |
6.32 | Moist Tropical Rainforest | Laguna del Tigre, Guatemala | Moreira et al. 2009 |
5.20 | Moist Tropical Rainforest | La Mosquitia, Honduras | Portillo-Reyes and Hernández 2011 |
Mean (per 100 km2) | 7.09 | ||
Standard Error | 0.81 |
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Miller CM (2006) Jaguar density in Fireburn, Belize. Report for Wildlife Conservation Society and Belize Forest Department: http://eprints.uberibz.org/7/1/Fireburn_Jaguar_Density_2005.pdf
Moreira J, García R, McNab RB, Ruano G, Ponce G, Mérida M, Tut K, Díaz P, González E, Córdova M, Centeno E, López C, Vanegas A, Vanegas Y, Córdova F, Kay J, Polanco G, Barnes M (2005) Abundancia de jaguares y presas asociadas al fototrampeo en el sector oeste del Parque Nacional Mirador - Río Azul, Reserva de Biosfera Maya. Wildlife Conservation Society-Programa para Guatemala, Guatemala.
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Moreira J, McNab RB, García R, Méndez V, Barnes M, Ponce G, Vanegas A, Ical G, Zepeda E, García I, Córdova M (2008a) Densidad de jaguares dentro de la Concesión Comunitaria de Carmelita y de la Asociación Forestal Integral San Andrés Petén, Guatemala. Wildlife Conservation Society - Jaguar Conservation Program, Guatemala.
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Moreira J, García R, McNab R, Santizo GP, Mérida M, Méndez V, Ruano G, Córdova M, Córdova F, López Y, Castellanos E, Lima R, Burgos M (2010) Abundancia de jaguares y evaluación de presas asociadas al fototrampeo en las Concesiones Comunitarias del Bloque de Melchor de Mencos, Reserva de la Biosfera Maya, Petén, Guatemala. Wildlife Conservation Society-Programa para Guatemala, Guatemala.
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