Based on my research back in 1964, the U.S. and Costa Rican governments approved our applied research program in 1995. Today, we have 185 hectares of R&D forests on 13 farms in Costa Rica built on the following new concepts of pasture reforestation to mitigate climate change.

1)  Most governments pay farmers to plant trees.  And most farmers cut the forests down when they can sell the timber a decade or so later.  The result is that there is no long-term C storage; it’s a short-term sequestration and mitigation effect in temporary forests.  In fact, we need permanent farm forests with permanent storage of CO2.slide3

2).  In addition to reducing our emissions to zero, James Hansen recently wrote about the need to extract and store 150 GTCO2 from the atmosphere to get us back to 350 ppm, a livable atmospheric content of CO2. Developing permanent farm forests to replace pastures on a large scale can be an important contribution towards that end.

3)  Of course, to reforest pastures on a large scale, we need to address how the farmer benefits.  Otherwise he won’t participate.  RTT has developed such a system applicable to the tropics.  Our strategy is to develop and demonstrate our RTT model on farms in Costa Rica, training students from other countries who study in our institutions.

4)  How much CO2 can we capture in a hectare?  Our best models for sequestration are stands of pure Klinkii (Araucaria hunsteinii) with over 2,400 MTCO2/ha in 50 years. These were my original research plots established when I worked for FAO and the UNDP.  However, we do not espouse pure stands of any species, rather, we work with mixtures of species as more ecologically stable and beneficial for our long-term goal of 100+ years of sequestration.

5)  How much income can a farmer earn?  Our research goal is $500/ha/yr combining grants and income from the sales of thinnings (RTT rules) and eventually from the sale of sequestered MT of verified CO2. Our oldest program forests in this UNFCCC-AIJ project, 18 years of age, have been thinned twice lightly, a process that will be repeated every 5 years to create a cash flow for the farmer.

All forests work with a 25-year contract between the farmer and RTT.  To achieve our goal of 100 years of sequestration in permanent farm forests, we envisage a series of 4 successive 25-year contracts.  The initial contract, 0-25 years, the U.S. forest sponsors receive information of the amount of sequestered CO2 in their forests annually.  During the following contracts, RTT expects to sell the future verified CO2 to the original donors or into other markets for the benefit of the farmer.

6) To establish the original forest, farm income begins with the awarding of a $2,000 to $4,000/ha grant to the farmer, along with free intensive technical assistance.  These amounts are fixed in the contract.  The latter, $4,000, is from an experimental trial of $2,000 for the forest establishment, and at 4 years, we begin paying the farmer $5/MT CO2 sequestered in the forest up to another $2,000.  This is one of several financial models we are testing.

7) To maximize the production of the forest, we use a system of light 15-18% thinnings every 5 years, thinnings so light as to leave small holes in the canopy that close rapidly and that stimulate growth.  Our basic rule for thinning is to thin to favor the best trees in the forest, taking out their biggest competitors and leaving the best in the forest. (Positive Auslese in German).  Loggers, if left alone, will take out the best trees to increase their profit, leaving big holes in the canopy depending on how many trees they extract.  Big holes make the forest less productive; they take longer to close.  So, vigilance is an important element in harvesting and sales.  RTT is responsible for the management of the forest in this early research stage in the contract.

Planted Cedar at 4 Years Old

A 4-year old cedar in a RTT mixture, shaded on the sides to form a clean stem, 3-4 logs

8)  To replace the thinned trees and to maintain production/sequestration, we are carrying out research to find native species that are shade-tolerant and that can be planted under the main stand.  These species are also selected based on the value of the wood produced.  They will grow up under the main stand, moving up into the main canopy as the forest is periodically thinned.  Because of their slow growth, the wood produced may be of higher quality.

Note that with this system, we can improve the quality of wood that the stand eventually produces through species selection, increasing the farmer’s income towards our $500/ha/yr goal.  Presently, a cubic meter of cedar (Cedrela odorata) standing in the forest is worth about $150, mahogany (Swietenia macrophylla) perhaps $500/cubic meter standing.

9)  The original stand is composed of a mixture of several significant species. Roughly, we plant 1/3rd Klinkii, 1/3 E. deglupta “hybrid”, and 1/3rd valuable hardwood species such as Mahogany and Cedar.

47 year old Klinkii

47 year old Klinkii

The Klinkii trees are planted and mostly left in the forest for long-term carbon storage.  This tropical conifer species can reach over 250 feet in height and 6 feet in diameter at breast height.  It is native to Papua New Guinea. It has been growing for over 50 years in Costa Rica.  It is shade tolerant and relatively fast growing although slow the first year.  Its columnar shape allows us to have very dense forests (= higher production and thus, sequestration.)  We seem to be getting very high sequestration rates in older plantations with Klinkii, 50+ MTCO2/ha/yr.


Deglupta on a good site, 16 years old.

I developed the E. deglupta “hybrid” in the ‘70s by crossing two provenances of this very fast growing tree species.  It is straight and produces good wood.  Its role is to produce logs that can be thinned at about 7 years of age for early farmer income.  Planted at wide spacing, it has a light crown under which Klinkii can grow very well in the original stand.

Finally, in a 4-species mixture of the original stand, we plant Mahogany and Cedar.  Both species produce very valuable wood that command high prices, again, towards our long-term income goal for farmers.  We are testing many other species in our forests and our long-term research related to forest management continues.

When we plant Mahogany and Cedar, we need to control the Mahogany Shoot borer (Hypsipyla grandella), using a relatively low-cost system that we have developed.

10)  Our research, operations and farm forests are sponsored by over 200 mostly U.S. donors, each forest using a 25-year contract between RTT and the farmers.  Forests are measured annually to guide our management att his stage of our applied research.  The donations to sponsor forests are deductible to the extent allowed by law.  Verification procedures are being developed through second parties.

11)  RTT is staffed by two foresters in Costa Rica.  In our headquarters, we have a director and a forest scientist, the founder of RTT.  Our research continues as we expand our forests to confirm the results.  Our website is

We believe that our RTT model forest, combined with farmer extension, will be a significant contribution to defining an important to the role of new forests that mitigate climate change.

Would you care to sponsor a 1-ha RTT forest?

Dr. Herster Barres
MF Yale, 1958; D. Tech. Sci, ETH, 1961.

The present line-up of species in our mixtures:

  • Klinkii, Araucaria hunsteinii, 6 ft in diameter and 273’ in height in PNG forests. Araucaria examples in city parks and cemeteries.
  • Deglupta, E. deglupta, fast growing “hybrid” for early farmer income. Annual income if planted 5 years in a row and thinned for the first time at 7 years.
  • Species that produce valuable wood. Cedar (Cedrela odorata) and Mahogany (Swietenia macrophylla) Other valuable-wood species for medium to long-term farmer income are being tested.
  • Sombra! Underplanting shade-tolerant species for long-term production of valuable wood.
  • How many species in our future mixtures?

Reforestation Models

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