The Monteverde-Arenal Bioregion (MAB), located in the Tilarán Mountains of north-central Costa Rica, contains some of the most biodiverse habitats in Costa Rica and also provides the backbone for some of Costa Rica’s most important ecotourism destinations. Several national parks and private preserves protect a large area of habitat in the region, but this complex of protected areas is isolated from other large protected areas because of deforestation associated mostly with agricultural development, plus a smaller amount of urban development. Furthermore, we are aware of no detailed analysis to identify landscapes in need of protection in order to secure the conservation of the region’s biodiversity into the future. Using GIS technology, we analysed select conservation-related ecosystem services in order to identify the lands of highest future conservation priority outside of existing protected areas in the MAB. We identified large areas of habitat on the Pacific slope to the south and west of the existing protected areas and habitat adjacent to Lake Arenal to the northwest of existing protected areas as having the highest ecosystem services values. In contrast, most lands on the Caribbean slope outside of the existing protected areas had comparatively lower ecosystem services values. Based on this analysis, we recommend that future conservation efforts, including potential land purchase, should focus on conserving mid-elevation Pacific slope forests and land along previously proposed biological sub-corridors that could connect the MAB to other existing protected areas. Our analysis shows that many important landscapes for biodiversity conservation in and near the MAB currently exist outside of protected areas, making many species found in those areas vulnerable to human activities. The opportunity to connect currently protected areas to one another through effective biological corridors still remains, possibly through conservation partnerships with landowners or direct land purchase, but time could be short as increasing development and changing land-use patterns threaten to further isolate habitats in the MAB.

Biological corridors, Costa Rica, GIS, land-use, Mesoamerica, Tilarán Mountains, tropical forest

The Monteverde-Arenal Bioregion (MAB), located in the Tilarán Mountains of Costa Rica, has some of the highest biodiversity in Central America and simultaneously represents one of the most important ecotourism destinations of the country (Aylward et al. 1996; Langholz et al. 2000; Koens et al. 2009; Stuckey et al. 2014). The area has several important public and private protected areas, the most important amongst them being the privately owned Children’s Eternal Rainforest (22,600 hectares) and Monteverde Cloud Forest Reserve (4,125 hectares) and the state-owned Arenal Volcano National Park (12,124 hectares), Alberto Manuel Brenes Biological Reserve (7,800 hectares) and Santa Elena Cloud Forest Reserve (310 hectares). Along with a number of smaller, mostly privately owned protected areas, the total area in conservation in our study area is about 50,000 hectares, including protected habitat in eight Holdridge life zones (Holdridge 1947, 1967; five regular + three transitional zones) on both Caribbean and Pacific slopes (Fig. 1).

Figure 1.

Study area showing boundaries of analysis (red outline), protected areas with ownership designation and proposed biological sub-corridors (in yellow outline) Moran et al. (2019).

The region is noted for its high biodiversity, especially for plants, amphibians and birds (Haber 2000; Wheelwright 2014; Newcomer et al. 2022). For example, the Monteverde area (defined as all lands above 700 m a.s.l. in the MAB) alone contains over 450 species of orchids, perhaps the greatest diversity in the world for a single area of similar size (Haber 2000). Numerous endemic species exist here (Newcomer et al. 2022), probably because of the relative isolation of the higher elevation habitats. The region is also home to a number of endangered or threatened species (e.g. Bare-necked Umbrellabird (Cephalopterus glabricollis), Baird’s tapir (Tapirus bairdii)), further solidifying the MAB as an important priority for conservation efforts in Costa Rica and beyond.

The area also is a prime location for ecotourism, with Monteverde and La Fortuna (as well as smaller nearby communities) hosting hundreds of thousands of national and international visitors annually (Koens et al. 2009). These high visitation rates, in turn, support a vibrant tourism economy focused on nature and biodiversity (Aylward et al. 1996; Langholz et al. 2000; Koens et al. 2009; Stuckey et al. 2014). Charismatic avian species such as the Resplendent Quetzal (Pharomachrus mocinno) and the Three-wattled Bellbird (Procnias tricarunculatus) are major attractions, as are dramatic geological features, such as the Arenal Volcano and associated hot springs. Subsequently, a large proportion of the local human population is involved in tourism and, in general, there is a strong conservation ethic in the local communities where ecotourism thrives (Newcomer et al. 2022).

While conservation efforts in the Monteverde-Arenal Bioregion have been successful, most of the land that has been protected to date is at higher elevations and/or includes steep terrain and is not well suited for traditional land use, such as agriculture. Lower elevations in the region remain mostly unprotected, resulting in an island of conservation in a larger sea of partial deforestation and development (Sánchez-Azofeifa et al. 2003; Moran et al. 2019). As a result, the MAB has lost connectivity with surrounding habitats, perhaps limiting the persistence potential of organisms that require large, connected tracts of habitat (e.g. jaguar, Panthera onca). However, studies have shown that this region retains much of its biodiversity, including large mammals that require extensive habitat (Zamzow et al. 2018) and that partially forested, privately owned corridors connecting the Tilarán Mountains to other protected areas do persist (Moran et al. 2019; Beita et al. 2021). As conservation efforts have primarily been focused on higher elevations, lower elevation slopes and their associated life zones (some of which are completely unprotected in our study area) and unique species remain vulnerable to deforestation and other negative impacts.

The MAB is also part of the Mesoamerican Biological Corridor, one of the most diverse ecoregions of the world, representing one of the identified hotspots of biodiversity on Earth. This large corridor connects the distant bioregions of the North and South American continents and is, therefore, of outstanding importance for both animals that need large ranges (e.g. Panthera onca) and species that migrate seasonally across the region (e.g. migratory Neotropical birds). Therefore, successful land conservation in this region will further the goals of larger Mesoamerican biodiversity protection (Miller et al. 2001; Harvey et al. 2008; Holland 2012; Jiménez-López et al. 2023).

In this study, we analysed select ecosystem services for landscapes in and around the Monteverde-Arenal Bioregion through the use of geographic information systems (GIS). Our goal was to identify priority lands for future conservation efforts, including direct purchase as well as other conservation initiatives. We hoped that we could identify areas that would be best utilised for conservation, while simultaneously identifying lands that are better left to remain in traditional economic activities, such as agriculture, businesses and other human infrastructure. We also sought to identify suitable potential biological corridors that could connect the MAB to nearby protected areas, as such corridors would represent high priority land for conservation for their ability to reduce regional fragmentation.

The MAB has large altitudinal gradients over a relatively small geographical area, resulting in many steeply-sloped lands (Figs 2A, B, 3). Most of the existing protected areas occur at higher elevations and in areas of steep slopes. Outside of the existing protected areas in our study area, the Pacific slope to the south and west has large areas of steeply-sloped landscapes (Fig. 2C), while land to the north and east of the existing protected areas is comparatively flat. The proposed sub-corridor connecting the MAB region to Juan Castro Blanco National Park has smaller areas of steeply-sloped lands, primarily in the major river valleys.

Figure 3.

Slope angle within study area.

Land use in the study area is highly correlated with land already under some measure of conservation or protection. Unsurprisingly, protected areas are almost entirely covered in tropical forest (of various life zones), which is the natural land cover of the entire region (Fig. 4). There are large patches of forest located to the south and east of the existing protected areas, especially in and around the proposed sub-corridor connecting the MAB to Juan Castro Blanco National Park. Smaller forested areas exist on the Pacific slope to the southwest of existing protected areas and there are other small patches of forest in the proposed sub-corridor connecting the MAB to Tenorio National Park to the northeast. Most non-forested land in the study area is pasture land devoted to cattle ranching (both dairy and beef, MDM personal observations), although substantial areas to the northeast of the main protected areas have cultivated crops (these areas also correspond to the lands with more gentle slopes, Fig. 3).

Figure 4.

Land-use within the study area.

The study area spans 11 Holdridge life zones. Most of the protected areas of the MAB fall within the lower montane rainforest and premontane rainforest life zones, with smaller areas of tropical wet forest transition to premontane (Fig. 5). The other eight life zones present in the study area are poorly protected and three are completely unprotected. Most notably, on the Pacific slope to the south and west of the existing protected areas, there is a series of closely altitudinally-spaced life zones that fall almost entirely outside of protected areas and also have high biodiversity values (Fig. 6) and some intact forest (Fig. 2C). Conversely, many lower elevational Caribbean slope life zones are also unprotected in their entirety within the study area, but are also almost totally cleared of native vegetation due to agricultural activity (Fig. 4).

Figure 5.

Holdridge life zones within the study area.

Figure 6.

Life zone-specific biodiversity rankings within the study area.

There are six major hydroelectric projects within the study area: one on the Pacific slope and five on the Caribbean slope (Fig. 7), the area that receives the most rain (Waylen et al. 1996). The Arenal facility is the most important generation facility in the study area, producing about 30% of Costa Rica’s total hydropower. In total, more than 1 million MWh are produced annually from water provided by protected areas of the MAB, about 10% of Costa Rica’s total electricity production and about 13% of its hydroelectric power generation (Our World of Data 2023), even though it represents less than 5% of the country’s terrestrial area.

Figure 7.

Hydroelectric resources within the study area.

When we combine all of the selected ecosystem services, the areas that should be given highest priority for conservation are generally located in two distinct locations: land on the Pacific slope to the south and west of the existing protected areas and land connecting Arenal National Park with the Tenorio Complex to the northwest of Lake Arenal (Fig. 8). Land to the northeast of the existing protected areas is generally of lower conservation priority. The connectivity gap between the MAB and Juan Castro Blanco National Park is made up mostly of lower priority lands with fewer ecosystem services as compared to the gap between existing protected areas and the Tenorio Complex.

Figure 8.

Conservation priority lands within the study area, based on all ecosystem services values included in the analysis.

Our analysis confirms the existence of unprotected lands with high conservation value in the vicinity of the existing protected areas of the MAB that should be the target of conservation activities. There are also areas that have comparatively less conservation value, showing that these types of analyses can help to prioritise the limited resources available for conservation. At this point in time, differentiating land more suitable for traditional economic activity from land that would be better utilised for protection of natural resources will be critical as societies try to balance economic needs with environmental and ecosystem services protection. This balance is even more critical for countries like Costa Rica, whose strong tourism (and especially ecotourism) sector outweighs benefits from extractive activities and depends on a healthy natural environment to sustain its economic well-being.

The first area which we identified as high priority for conservation includes lower elevations on the Pacific slope to the south and west of the existing protected areas in the MAB. This region has a high number of closely altitudinally-spaced life zones, several of which have high species diversity and endemism. The life zones in this area are also poorly protected in the study area (and in Costa Rica in general). As the climate in these life zones tends to be favourable for cattle ranching and coffee growing, much of this habitat was deforested many years ago for agricultural use. However, some forested areas remain, especially on steep slopes and in riparian zones. Additionally, these areas have experienced an increase in reforestation over the past few decades as the more marginal agricultural areas have been abandoned and allowed to regenerate (Chacón-Cascante et al. 2012).

The second priority area for future conservation efforts lies between Arenal National Park and the Tenorio Complex, to the northeast east of Lake Arenal. There are actually two potential corridors here: one along the sub-corridor proposed in Moran et al. (2019) and another along the northern shore of the Arenal reservoir. Both areas have relatively high forest cover and fall within this important watershed for Costa Rican electricity production. These areas are also sparsely populated (with the exception of La Fortuna and adjacent communities), with most deforested lands devoted to cattle ranching (MDM, personal observation) and almost no permanent crops or human settlements (Fig. 2D).

The establishment of biological sub-corridors that extend outwards from the existing protected areas of the MAB would conceivably be positive in supporting populations of animals that need large areas for viable populations (Weber and Rabinowitz 1996; Crooks and Sanjayan 2006; Hilty et al. 2012) and in helping some species survive the dispersal expected to be necessary to adjust to climate change (Heller and Zavaleta 2009; Fung et al. 2017; Beita et al. 2021). The Bellbird Biological Corridor was created in part to protect and improve habitat for altitudinal migrants, such as frugivorous birds and some Lepidoptera (Welch et al. 2011; Newcomer et al. 2022). As this analysis shows, land within and adjacent to this corridor also has high value for many other ecosystem services, such as high biodiversity and soil conservation on steep slopes. The proposed corridor between the MAB and the Tenorio Complex would help to connect the protected areas of the Cordillera de Tilarán (MAB) to protected areas in the Cordillera de Guanacaste (with numerous important protected areas), which apparently have healthy populations of Baird’s tapirs (Tapirus bairdii, Carbonell and González-Zúñiga 2000) and jaguars (Panthera onca, Montalvo et al. 2022), two species imperiled in Costa Rica. These two species are present in the MAB, but only at low population densities (Zamzow et al. 2018) that are likely not viable in the long-term. With the larger populations of tapirs in the Tenorio Complex and jaguars across the Cordillera de Guanacaste into the tropical dry forests beyond (Calvo-Alvarado et al. 2009), a corridor connecting these areas to the MAB would likely increase probabilities of survival for these species across north-central Costa Rica.

A third potential area of focus, extending from the MAB to Juan Castro Blanco National Park, is more problematic. While the western part of the proposed sub-corridor has abundant forested lands of high conservation value (Fig. 4), the eastern portions comprise landscapes with comparatively low ecosystem services and include extensive areas of pasture and cultivated lands (ornamental plants are a large industry in this region). Creating a functional biological corridor in this area would, therefore, likely be expensive and logistically difficult. Considering economic limitations for land acquisition and other conservation efforts, it would, therefore, be preferable to focus on the other two areas mentioned above (Bellbird and Arenal-Tenorio).

The entire region falls within the Mesoamerican Corridor proposal (Miller et al. 2001), which extends from Panama to Mexico, with the jaguar (P. onca) as its flagship species. Due to political instability and other social challenges throughout the region, the creation of a functional mega-corridor remains a logistical challenge. However, within Costa Rica, the completion of this corridor is more feasible, given the large amount of land currently under protection, the historically strong conservation efforts country-wide and the long-term political stability of the country. The opportunity to create benefits for the local economy by ecotourism may also foster the completion of the corridor in Costa Rica. There are only relatively small gaps between large protected areas, so that a small, carefully targeted increase in lands under conservation could potentially link all of Costa Rica’s major protected areas across the entire length of the country. Ultimately, if Costa Rica hopes to preserve its rich biodiversity in perpetuity, this landscape-scale conservation strategy is probably the best method. Fortunately, with the already extensive system of public and private protected areas, along with focused efforts on remaining lands that retain high conservation values, there is a good probability that Costa Rica can continue to be a model for 21^st century conservation.

This analysis shows that conservation efforts in the MAB have been successful in creating a large complex of biodiverse protected areas. Yet these areas remain an island of protected lands isolated from larger regional protected areas and several life zones remain completely unprotected. However, land of high conservation value and low traditional economic value remains that, if placed under conservation, could mitigate these two issues. Considering the incredibly high contribution of this area to Costa Rica’s total biodiversity and the large ecotourism economy dependent upon this biodiversity, we urge conservation organisations to consider how to achieve expanded, but selective land conservation of the MAB, possibly through a combination of direct land purchase, ecotourism development in these areas and cooperative agreements between landowners and conservation organisations. Examples of direct land purchase priorities might include some of the highest conservation priority areas of the Bellbird Biological Corridor directly adjacent to protected areas and/or the smaller unforested areas of the Tenorio Corridor that would, if reforested, connect larger areas of forest together. However, since direct purchase of all high conservation priority lands is financially and logistically difficult, we expect that cooperative work with private landowners will be the primary way to achieve greater success in preserving the rich biodiversity of this region.

We wish to thank the Alex C. Walker Foundation for their generous funding for this project. Peter Gausmann and João Pompeu provided valuable feedback that improved this manuscript.