Protecting Life Zones:  The Bellbird Biological Corridor

The term “life zone” describes a geographical area that has a particular temperature, elevation and climactic range.  Plants or animals are suited to live in a particular life zone (or zones, depending on the species’ adaptability).  Many species do not have the flexibility to live in more than one life zone, and so the loss of one type of habitat means the loss of the species that habitat supports.

Little Life Zone Overlap for Most Species: This chart shows that a species of plant or animal might be adapted to live either in a Cloud Forest life zone, or a Rain-Shadow Forest life zone, but not both. Losing one type of habit means losing the creatures and plant life that depend on that habitat for survival.

On the Pacific side of the Monteverde region, for example, the Children’s Eternal Rainforest extends from the center of the country towards the Pacific Ocean.  As one descends from the protected forests at the top of the mountain to the coast, one passes through seven distinct types of forest or life zones. Each is unique in its own right, and collectively they harbor a flora and fauna that is quite different to most of that currently protected in the CER and neighboring reserves.

Three Wattled Bellbirds: These birds cannot survive in the Monteverde Region without the habitat that supports them.

There is an additional reason why the land just below the existing CER at the top of the corridor is of special importance. At that particular elevation on the Pacific slope lies what is known technically as the Premontane Wet Forest life zone. This is an elevational belt that has barely received protection, and only 7.5 km2 of this type of forest remains intact in the Monteverde region. Several plant and animal species are unique to these forests; other animals rely on them for portions of the year. For example, almost the entire population of Monteverde’s Three-wattled Bellbirds and Resplendent Quetzals packs in to the pieces of forest that are left at this elevation between the months of July and September.

Because of the dependence of the Bellbird on this tract of land, this region is referred to as the Bellbird Biological Corridor, although many other species also depend on this area for support.  Following is a description of the life zones in this region.  This remarkably diverse set of habitats in a relatively small place.is the hallmark of the Children’s Eternal Rainforest and one of the fundamental reasons that the forest is so unique.

The Resplendent Quetzal: The incredibly beautiful and extremely elusive Quetzal depends on the habitat provided by the Pacific slope’s life zones. (Photo courtesy of Wikipedia.)

Description of Life Zones in the Bellbird Biological Corridor

(This document was written by Debra Hamilton. She is the founder of the Costa Rican Conservation Foundation, an organization created primarily to address habitat loss on the Pacific slope of Monteverde, and a partner in the BBC.)

Lower montane rain (1550-1850m):  This area is only found at the upper reaches of the corridor on the continental divide and is known as cloud forest in Monteverde.  It is typified by elfin forest, high epiphyte loads in a misty, windy climate.   Epiphytes are commonly of the Ericaceae and Melastomataceae families (Hartshorn 2002).  The ground layer is comprised of ferns, sedges, herbs, and mosses.   Lower montane rain forest is 7.4% of the area in the country (3781 km2) (Holdridge et al 1971).  This habitat type is well protected in Monteverde (Powell and Bjork 2004), through the protection of the Monteverde Cloud Forest Reserve, the upper most end of the CBPC.

Lower montane wet (1450-1600m):  This area is known as lower cloud forest in Monteverde and is important as the reproductive area for the Resplendent Quetzal and Black Guan is well known. These evergreen forests are characterized by lianas, epiphytes, ferns, Begonia, aroid vines, orchids, bromeliads, Araceae (Hartshorn) and dominated by Lauraceae trees.  The limitation of this habitat type is of great concern with only 1.5% of the area in the Costa Rica in this life zone (767 km2).  More alarming is that only 11 km2 remain in Monteverde in the form of forest fragments and only 81km2 are protected in the entire country (Powell and Bjork).

Premontane wet forest (non transitional) (800-1450m):  Commonly referred to as rain shadow forest in the corridor, this life zone is appreciably drier than the upper regions with only 2000-2500 mm of annual precipitation.  The forest is two layered and lacks the high epiphyte loads and tree ferns found in the cloud forest.  Lauraceae still dominates for tree families.  Of land area, 5.1% of the country is in this life zone (2606 km2) (Hartshorn) but only 39 km2 is protected (Powell and Bjork 2004).  Approximately 75% of this life zone has been deforested in Monteverde and only approximately 7.5 km2 remain as forest fragments (Powell and Bjork 2004).

Premontane moist forest (700-1000m) (non transitional):  According to Hartshorn, this is the most altered life zone in the country (1.4% of the country 716 km2) with no significant tracts of forest in this life zone type remaining in the country.  They are forests of medium height, semideciduous trees, and dense shrub layer (Hartshorn 2002)

Tropical moist forest (premontane  (cool) transition) (600-800m):  (from about half way between San Luis and Guacimal to 800m) Only about 23% remaining in forest (in the country primarily in the Corcovado, Carara, & Cabo Blanco protected areas, none of which are within the corridor or contiguous with the Monteverde area). This life zone is very limited in area in the country at only 3%;1533 km2)

Tropical moist (0 – 600 m):  These forests on the Pacific slope are in the rain shadow of the continental divide and experience a longer dry season (six months) than higher elevation forests on the Pacific side (and, obviously, Caribbean slope forests).   This life zone is very discontinuous in the country, yet extensive (20.3% of land area in the country) (Hartshorn 2002).  The forest is tall  with wide crowns and slender trunks.  Many trees are semi-deciduous, losing their leaves as a mechanism to survive the dry season.

Tropical Mangrove Forest (sea level): The lowest area of the corridor is a well known endangered habitat type—tropical mangroves.  Four species of mangrove trees are found here, red (Rhizophora harrisoni), black (Avicennia germinans and Avicennia bicolor), and white (Laguncularia racemosa).  The mangroves are critical habitat for many marine animals such as shrimp, crabs, lobsters, sponges, fishes, octopi, oysters, corals, barnacles, algae, etc.   They are the reproductive areas for many of these organisms.  Mangroves are also productive areas for many species of seabirds such as Magnificent Frigatebirds, Roseate Spoonbills, Osprey, Comorants, herons, egrets, as well as the Mangrove  Hummingbird, a species of concern in Costa Rica.

*Information for this article was provided by Mark Wainwright, President of the Monteverde Conservation League.