Cloudbridge’s primary concern initially was with the reforestation and restoration of the native forest and habitats. Research helped to identify trees and other flora that are native to the oak-dominated lower montane cloud forest of the Talamanca range. In this effort, assistance was provided by Jennifer Smith of Tierra Segura as well as forest experts such as Freddy Rojas of ITCR and Barry Hammel of INBio. See the Cloudbridge Project overview .

Step 1: Selection of Trees to Plant

The trees originally planted are:

  • Quercus costaricensis,
  • Quercus rapurahuensis
  • Sapium pachystachys
  • Citharexylum caudatum
  • Cornus disciflora
  • Tecoma stans
  • Persea caerulea
  • Manilkara zapota
  • Ulmus mexicana (see picture)
  • Cedrela tonduzii
  • Cupressus lusitanica
  • Alnus acuminata
  • Tournefortia volubilis, a shrub-like tree, known locally as “frutilla.”
  • Quercus seemannii (roble),
  • Magnolia poasana, a flowering tree
  • Ocotea ira (aguacaton), a fruiting tree

Some of the trees were selected with the potential for commercial forestation in mind, as a demonstration project. These are faster-growing and marketable. At the same time they must be trees that are native to the surrounding forest. The initial tree selection comprised Cupressus lusitanica (cypress, cipres)  which is not native but common and Alnus acuminata (alder, jaúl).

Alnus acuminata (picture at right) is valued for its wood, watershed protection and soil improvement. Because it is a nitrogen-fixing tree, it enriches soil quality as it grows. It is a fast-growing pioneer species that regenerates naturally in open, disturbed areas. It is found in zones with extra soil moisture such as cool, tropical highlands, and cool, high-latitude regions with abundant rainfall where mist and cloud cover can be a source of fog-drip precipitation. In the tropical highlands of Central and South America, clouds and mist are important in supporting A. acuminata and grass, when associated, through the dry season.
Cupressus lusitanica , cipres, is native to Mexico and probably Guatemala but now widely planted at high elevations throughout the tropical world. Height may exceed 100 ft with a bole diameter of 2 to 3 ft, sometimes reaching 5 ft. Logs are usually well shaped, straight, and cylindrical. It requires good drainage.

Parts of the Cloudbridge reserve, notably those next to existing primary forest, are given over to natural regeneration. Dense shubbery and light-loving pioneer species such as Guarumo (Cecropia peltata) prevail in these areas. Cecropia is an important tree because it grows easily and rapidly in disturbed areas.  It is also important to biodiversity, because of its symbiotic relationship with the azteca ants that live in its hollow trunk, and because its foliage attracts three-toed sloths (which we would like to see reintroduced to this part of the cloud forest).

Step 2: Acquisition of Trees

Initially, we purchased saplings from high-altitude nurseries. We used the Instituto Technologico de Costa Rica in Cartago (Freddy Rojas) and Apa-Roble in Division (Jose Angel Cespedes R.). The trees from Apa-Roble, which lies at an altitude similar to that of Cloudbridge, included Cedrela tonduzii (Cedro dulce or sweet cedar) and a variety of saplings pulled from the jungle.

In the second year, we experimented with saplings culled from the surrounding cloud forest on Cloudbridge. The leaves of these soon turned brown from shock, but most recovered within a few months. We also nurtured seedlings in a vivero, and even succeeded in growing native oaks directly from seeds planted on site.

The trees were delivered to San Gerardo de Rivas, then transferred by truck 2.6 km to the end of the road, at Casa Amanzimtoti. We used horses to carry the saplings the remaining 1 km to the Cloudbridge site. Each tree came in a little black plastic bag. Some did not make it.


Ulmus mexicana. Common name: elm or tirra

Some of the saplings, notably the tirras (elm, ulmus mexicana), were tiny. We feared they would not survive. We planted them anyway, and with diligent care almost all of them, like the one in the picture, were alive two months later. As long as they are cared for, small saplings seem to have as good a survival rate as larger ones.


Step 3: Planting the Trees

First, where to plant? Drainage, soil quality, accessibility and biodiversity goals were our main considerations. It was decided to plant the commercially attractive jaul (alder) and cipres (cypress) in three rows alongside the main trail that bisects Cloudbridge. Given the terrain and the high drop off from the trail to the flatter lower meadow next to the river, putting these trees in lines more or less along the fence meant that they will have adequate competition to grow tall and straight as well ensuring that they can be cut out economically and easily, protecting against damage to surrounding trees. These trees were planted 3 meters apart. In the picture, Jennifer Smith and Ignacio discuss the reforestation plan.
The remaining trees were spread over the lower pasture, and, when that was filled, up the slopes of the upper pasture. These trees were planted 5 meters apart. The soil turned out to be rich (though rocky) and erosion was minimal. In the picture, the horizontal line of trees marks the main path. Rows of alder and cypress have been planted alongside it. The Lower Meadow, below the path, is fully populated with mixed trees. Some of the Upper Meadow has been planted too, also with a mixture of species. All the holes were dug first, in preparation for delivery of the trees, which were planted as soon as possible after their arrival.  The hole was dug at least 50 centimeters deep and 50 cm wide, and an area about 1 meter in diameter around it is cleared. The seedling was removed from the plastic bag and planted with its soil, and the hole refilled and packed tightly.
Some trees, such as Tecoma stans (candelillo), are not suited to steep slopes but are adaptable to poorly drained soil which made it a good choice for planting in the lower section of Cloudbridge along the river where water tends to drain and stand at times. Tirra (Ulmus mexicana), on the other hand, grow fast and well on slopes. We found that the oaks (Quercus spp.) are adaptable to a wide range of terrain, and do better if partially shaded — in contrast to others like Cedrela tonduzii (sweet cedar) and Alnus acuminata (alder) which thrive in full sun.

A mixture of all the trees was planted near the house, on about one hectare. Like the commercial forestation section, these are intended to offer a demonstration of forestry. Visitors will see them as they pass to visit the Pacifica Waterfall or the Cloudbridge Reserve.

To a limited extent, we have tried “planting by estacas” — a useful supplement to planting seedlings. Estacas are branch cuttings that are transplanted. It is said to be important to do estaca work in the first seven days after the full moon which is known as the “menguante.” The theory behind planting in menguante is that the fluid in the plant is mostly found in the roots while the moon is waning because the gravitational pull by the moon is less. Several sources of the following two trees have been identified and can be planted by estaca.

Erythrina poeppigiana (Poro, Flame or Coral Tree)

“Fence-post tree” with excellent nitrogen-fixing qualities. Also used a shade tree for coffee plants. Leguminous. (Located in many places on Cloudbridge owing to its usefulness as fence posts for the previous cattle fencing). A branch is cut off and simply planted in a hole at least 50 cms deep. The estaca should be watered consistently for two weeks to insure that it regenerates its roots — nature does this during the rainy season, June-November.



Spondias purpurea (Jocote, Wild Plum)

Several Jocote trees line the roads throughout San Gerardo and are characterized by a filigree looking leaf structure. This tropical fruit tree indigenous to Mesoamerica can also be propagated by branch cuttings 8 to 10 cms in length and 1.5 cm in diameter during the manguante. They should not be planted deeper than 30 cms. It will take three to five years before fruits can be harvested. They are very tasty when ripe although they do have a large seed. Their flavor is creamy, acidic and sweet at the same time.

Step 4: Maintaining the Trees

The first few months of a tree’s in-the-ground life are crucial. In the rainy season, from July to November, the grass and weeds grow quickly and can overwhelm the baby trees if left unattended, as the picture suggests. Not only must there be a clear circle (rueda) around the sapling, but also the ground must be free of encroaching roots. We have never used fertilizer or herbicides.

Clearing is required at least once every 4-6 weeks. This is done by machete. It takes about two weeks of hard work by 3 to 4 people to clear the ruedas around all the saplings.

Saplings must be watched for insect attacks; some end up like this one. The culprit is probably leaf-cutter ants.
Inspection of the saplings – some trees require special care. Cedro Dulce (Cedrela tonduzii) is vulnerable to a pest called “mariposa” (hypsiphyla grandella), a worm of sorts which bores into saplings under two years old. Mixing them in among other trees, as we have done, seems to have deterred the pest. They need regular inspections to avoid infestation. In case of infestation, a special “poda” (pruning, see below) must be performed immediately to cure the tree or lose it. Mulching the baby trees by covering them with leaves and organic matter can also deter any infestation. After two to three years, the danger of infestation has passed.

At year one, the Cipres trees (Cupressus lusitanica) will need special maintenance referred to as the “poda” when the lower branches are trimmed to within 45% of the entire tree height.  Stakes mark the young trees and provide support against winds It’s difficult to keep track of the young trees among the encroaching undergrowth, so they are marked with stakes. These stakes or estacas were cut from the surrounding bush. We have also used fence posts, as the farm’s barbed-wire fences were dismantled, and the thin bamboo that grows in clumps on the forest’s edge.  On the other hand, like everything here, if you stick it in the ground, it grows! Hence the stakes have to be trimmed or turned lest they shade the trees.

Step 5: Monitoring Progress

In the first year of planting we were concerned about several things: whether the smallest trees would make it; whether the rapidly growing grass and weeds of the former pasture would overwhelm the saplings; how fast the different trees would grow; to what extent rain and wind would damage the trees; and what other threats, including pests, would be encountered. We also wanted to have a periodic measure of the health and growth rate of the different trees, and to correlate these with different conditions.

The monitoring project began in late 2003, a little over a year from the first plantings. The methodology is described in the Research Reports section of this website, along with links to the data that we have collected to date. The measurements have been supplemented with a photographic database. Here’s what we have concluded so far:

  • Identification can be difficult, and requires a written Guide (which we have now compiled) as well as practice.
  • Stakes are needed to locate the trees, and in a few cases to support them.
  • As expected, the trees are growing at different rates. The growth rate is affected by light, soil, drainage, root competition and other factors — but the biggest difference is by species.
  • Approximately 7% died within the first two months, mostly the result of shock and transport trauma. By the end of the first year, we estimate that 15%-20% had died or were lost in the undergrowth. A far smaller percentage perished in the second year of planting, as we learned how to maintain the plantation.
  • Nursery-grown trees seem to be more robust than seedlings pulled from the forest. However the latter usually recover from their initial shock. The few seeds that we have planted directly have done surprisingly well.
  • Some of the trees that we have planted are sun-loving pioneer species, and they seem to grow well in exposed areas. Examples are Alder (Alnus acuminata) and Yos (Sapium pachystachis). Others are slower-growing, shade-tolerant trees. These include Dama (Cytharexylum donnell-smithii) and Oak (Quercus spp.). In between are species like Mexican elm (Ulmus mexicana) and Sweet cedar (Cedrela tonduzii).

Step 6: The Future: More Trees to Plant

“Planting by estacas” project referenced above has gone well and will be continued.  More oaks and laurels, including many saplings gathered from the primary forest on Cloudbridge have been planted. We have grown hundreds in our own nursery. Other lower montane species that we are interested in planting include the canopy trees native to the Talamancas and several local fruit trees, used by birds and animals. These are listed on our Trees page, which also provides links to identification and natural history guides for each species of tree.
Alnus acuminata – We have received a number of inquiries from others wishing to undertake reforestation projects in Costa Rica. Here are some guidelines that we employ and that may prove of interest to others.

  1. Naturally, with such a rich variety of trees native to Costa Rica’s mountain forests, the first choice is those that have evolved to thrive in these conditions. Among those we would recommend would be the jaúl (Alnus acuminata) and the tirra (Ulmus mexicana) and yos (Sapium pachystachys) and cedro dulce (Cedrela tonduzii). And the oaks or robles (Quercus – any of the several local species, Q. costaricencis, Q. copeyensis Q. oocarpa, Q, seemannii and Q. rapurahuenis). Some, like A. acuminata, provide the additional benefit of being nitrogen fixing — they generate a natural fertilizer. We have had success planting the robles (oaks) from acorns in sunny, well drained areas, and we’ve seen roble do well in partially shaded locations. Jaul, tirra and yos thrive in sunnier spots. Visit us, and you’re welcome to take home as many acorns as you can carry.
  2. We have planted many fruit trees with agreeable results. They attract birds and insects and monkeys, and make one’s surroundings much more lively. Here are some suggestions for fruit trees:   
    • Aguacatillo (Persea caerulea), the wild avocado, is an essential part of the diet of the bellbird, the endangered quetzal (Pharomachrus mocinno) and other trogons. Quetzals and three-wattled bellbirds (Procnias tricarunculata) are altitudinal migrants and require Lauraceae (members of the laurel family, such as aguacatillo) fruit at different mountain heights for year-round survival. Similarly, aguacatón (Ocotea ira) is species of avocado.
    • Dama (Citharexylum donnell-smithii), the juniper berry
    • Manzana rosa (Eugenia jambos), rose apple
    • Frutilla (Tournefortia volubilis). Even the dead leaves of tournefortia attract certain butterflies.
    • Guayaba de montaña (Inga species, wild guava)
    • Papayillo (Didymopanax pittieri). A pioneer species, it is seen in disturbed areas of the Talamanca range. Flowering is concentrated in the rainy season and fruiting in the early dry season. Many birds eat the fruit, and insects the flowers.
    • Annona (Annona Muricata). Anona or soursop is a perennial, tropical fruit tree with a fruit that looks like a ball with big green spikes.
  3. Because of their rapid growth, it seems tempting to plant eucalyptus, cypress (Cupressus lusitanica) and other foreign species — but in our homeland of South Africa where we have another nature reserve, Wildcliff, one can see the damage that exotic species have wrought. One should be very careful about introducing alien plants particularly those from other continents. (C. lusitanica is from Mexico, and does not seem to take over pastures, but we have heard that there may be a plan to begin to eradicate it from the Chirripo National Park.) Even Poro (Erythrina) and Llama de Bosque (Spathodea campanulata) are non-native, but our conclusion from reading studies is that they do more good than harm if planted in limited quantities (they will both be shaded out by the maturing forest, eventually.) Sometimes the danger is not apparent for decades. South Africans are now engaged in a nationwide effort to eliminate its invasive aliens, particularly the Australian black wattle, Acacia mearnsii,  which grows as a monoculture and provides very little habitat or food for wildlife and whose roots deprive neighboring plants of water and nutrition. Often a problem is that such exotics have no local predators, so they grow unchecked.

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