Reforest The Tropics

An applied research program demonstrating climate change mitigation through sustainable farm forestry

Impressive Carbon Capture Verified

Measuring carbon in trees

Measurements of a Klinkii tree are being taken for the carbon verification process.

For decades, Reforest The Tropics has been measuring the productivity of its forest plantations. In June 2017, for the first time, RTT contracted with an accredited third party, EARTH University, to verify its carbon claims under the protocols established by the International Organization of Standards. The results are fantastic news for RTT and anyone with an interest in global sustainability. Verified forests are averaging 23.66 metric tons (MT) of CO2e capture per hectare, per year! To help put this into perspective, most literature on tropical reforestation demonstrates carbon capture of 10-15 MT of CO2e capture under favorable conditions. In other words, RTT is essentially doubling the carbon capacity of current, successful reforestation projects.

One of RTT’s longstanding research goals was to design a mixed-species forest that can capture and store an average of at least 20 MT of CO2e per hectare, per year. Internally, we recognized this target was ambitious, however we have maintained the belief that lofty goals are fundamental to fulfillment of our mission of ‘making a tangible contribution to global sustainability.’ Not only have we met this objective, but we are exceeding it.

The amazing carbon capture of RTT forests is only part of the story however. Two additional pieces distinguish the RTT approach:

  1. RTT’s mixed-species forests are more beneficial to the
    biome than ubiquitous single species monocultures, and
  2. RTT forests are designed to generate perpetual income,
    which allows partnering landowners to participate in the
    project over the long-term.

Essentially, RTT is planting some of the worlds most productive forests…is doing so in more environmentally beneficial manner than typical reforestation models…and is working to ensure they will remain standing indefinitely. Impressive Carbon Capture Verified RTT has focused on forestry research for many years.

Dozens of different planting matrices and mixtures of species have been investigated in order to discover the optimal design to achieve RTT’s three research goals:

  1. Sequester 500 MT CO2e over the initial 25-year
    contract period,
  2. Generate $500 income for the landowner per hectare
    per year, and
  3. Create a ‘permanent’ (read 100+ year) farm forest.

    Carbon verification in the forest

    Carbon verification team from EARTH University joins RTT staff and farm personnel to conduct their field work.

The verification process certified carbon from 8 different designs. The most productive forest was able to capture a phenomenal 34.21 MT CO2e per hectare per year for the Mohegan Sun Casino. Conversely, the least productive design achieved a respectable 11.9 MT CO2e per hectare per year. This design is noteworthy, however because one of the species in this mixture succumbed to a disease and had to be removed. Despite the elimination of hundreds of trees, the 5-year old forest is still productive and will only improve in terms of carbon capture as it matures. This example highlights the importance of RTT’s mixed species orthodoxy and offers a fair warning to advocates of a monoculture approach. Furthermore, if we remove this outlier from our analysis, verification results show that RTT forests are actually storing 25.38 MT CO2e per hectare per year.

The Big Picture: If RTT can plant a forest that doubles or triples CO2 capture of the most common reforestation models per hectare, we only need half the land (or less) to extract a corresponding amount of CO2. We at RTT have long known this is possible and now we have official verification of the RTT model’s potential. We thank you for your support as we spread the word.

Greg Powell
Executive Director,
Reforest The Tropics

Westerly, RI Middle School Forest Update


This is the 2.5 acre, 5 ½-year old forest established by Reforest The Tropics for the CO2-emissions account of the Westerly, RI Middle School.  In a 25-year contract between RTT and the farmer, this forest is legally dedicated to sequestering and storing CO2 for this school’s account.  So far, it has captured 42 metric tonnes of CO2 equivalent at 5 years of age when last measured.  That’s 92,500 lbs of CO2, the equivalent of 4,625 gallons of diesel used in their school buses offset in this forest.

Reforestation Models

Stand of Klinkii Trees on a Good Site

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?

It’s Not Too Late…


The scientific world was shaken recently with a report published in Nature, lead-authored by Joeri Rogelj of the International Institute for Applied Systems Analysis, which suggested that that we have already crossed an important global sustainability threshold. The report argues that, “the window for limiting warming to below 1.5 degrees Celsius with high probability and without temporarily exceeding that level already seems to have closed.” Under conventional thinking, it is undoubtedly closed, however we can still achieve our sustainability goals through negative-emissions technologies. The report makes the case, as have others, that emissions reduction strategies alone are ineffective. In other words, if we don’t start aggressively removing carbon dioxide from the atmosphere, we are in deep trouble.

Yale University Forest Image

An 8-yr old mixed-species forest for Yale University has already captured over 200 metric tons CO2


Readers of this newsletter, and followers of Reforest The Tropics in general are already well aware of this reality. We have been showing the math for years. There is simply too much CO2 already present in the atmosphere. We have reminded supporters that the residency rate of atmospheric CO2 is hundreds of years and we have drawn the inescapable conclusion that if we do not pull it out of the atmosphere in large quantities, then all our emissions reductions efforts are futile. We have shared the knowledge that even if we were to reduce our emissions to zero, today, the planet would still experience significant climate change due to the longevity of existing, excessive CO2. Of course, the only reliable, efficient, and safe means of accomplishing large-scale carbon extraction is through massive reforestation efforts in tropical zones. Our friends at the Woods Hole Research Center have consistently reinforced this message. In their latest newsletter, President and Executive Director, Dr. Philip Duffy argues that “it’s too late to control climate change solely by reducing future emissions of greenhouse gases—there’s too much CO2 in the atmosphere already for that to be sufficient.” Dr. Duffy continues that the “time-honored process of photosynthesis” is key to removing excessive atmospheric CO2.

Given this knowledge, it may seem strange that more focus is not given to the tropical reforestation solution. Skeptics of the reforestation approach tend to point to two challenges. First, it is argued that large-scale reforestation may adversely affect our ability to feed the planet, as agricultural land is transitioned to forest. Under conventional reforestation models, this argument has some small validity. The RTT model, however captures and stores CO2 much more efficiently than traditional models. Not only is our rate of capture 3-5 times greater than common models found throughout the literature, but our ceiling is much higher as well. Most forests (including old growth primary rainforests) tend to max out at 250-400 metric tons CO2 per hectare (with limited exceptions). RTT forests reach 500 metric tons within 25 years and some of our older research plots have reached over 2000 metric tons in a single hectare! The implications are clear. We need much less land dedicated to carbon sequestration if we are using the RTT model. Also, skeptics contend that forests are risky due to land-use changes. Again, this is a valid criticism if we look at typical reforestation efforts. The RTT model distinguishes itself in its ability to provide competitive income for a farmer. Our goal is to create a forest that can compete with cattle farming as a viable land-use option. Data from RTT forests shows that a farmer can earn a decent living through forestry and has no economic reason to ever cut the forest down. This income can last for generations, as RTT forests are designed to be productive indefinitely

Home Depot  Forest Image

RTT Forester, Victor Martinez stands in front of a forest planted for Home Depot in 2002. This forest already contains over 400 MT CO2!

It is time that the promise of the RTT model be shared with the world. We need your help. Please join us in our efforts to nudge business leaders and policymakers from their slumber in respect to the potential of tropical reforestation in general and the immense power of the RTT model specifically.

Environmental Education Program from the Forest


Using technology from the forestRTT recently launched an exciting new module to its educational program. In photos taken in both Costa Rica and Rhode Island, Greg Powell, the RTT Director, is giving a presentation about RTT forests to students at the Westerly Middle School. Greg, and RTT Forestry Engineer, Victor Martinez were able to make the presentation from Costa Rica using video-conferencing equipment funded by The Rotary Club of Westerly. Students were able to ask RTT staff questions about their forest in real time and learn about the importance of reforestation as well as specific elements of RTT’s reforestation approach. This level of connectivity between a school and their efforts towards sustainability is truly unique. RTT believes this type of engagement will foster a deeper understanding of the issues surrounding global sustainability for students throughout the region, moving forward.

Carbon Markets and Climate Change


This past February marked the 10th consecutive month in which the average global temperature set a record for warmth. Scientists are warning that the current rate of warming is unprecedented in the known history of our planet. As our globe continues to warm, it is becoming increasingly clear to even the most entrenched skeptics that we have a responsibility to address the excess carbon dioxide in our atmosphere.

When a corporation, institution, individual, or other entity wishes to balance their carbon emissions, they often first turn towards efficiency measures. Light bulbs are changed, insulation is installed, packaging is reduced, transportation is addressed, and other activities are pursued that limit energy use and reduce carbon emissions. Even the most aggressive investments into energy efficiency however will not yield carbon neutrality. The one option to balance remaining carbon emissions is the pursuit of carbon offset projects.

The World Bank has stated that carbon is the world’s fastest growing commodities market, with an annual value approaching $200 billion.  These carbon offsets come in various forms. Most common are credits that are given for renewable energy projects (solar, wind, geothermal, etc), improved forest management (managing forests in a manner that allows them to store more carbon than the norm), credits for avoided deforestation or degradation (the UN’s REDD mechanism allots credits to countries that limit deforestation beyond historical averages) and reforestation.

Fraud in the carbon market

A closer look at the inner workings of these strategies, however, exposes some uncomfortable realities. Horror stories of massive fraud are easy to find on the internet and exist across all sectors of the carbon market.  Due to lax regulations and the difficulties in monitoring, various bad actors have gamed the system to issue millions upon millions of fraudulent carbon credits. An investigation conducted by INTERPOL in 2011 revealed that “up to 90% of all carbon trading in some countries was a result of fraudulent activities. This fraud was estimated to have resulted in the losses to several governments of around 5 billion euros in just over 18 months.”

These examples have soured many individuals, policy makers, corporations, and institutions on the validity and efficacy of carbon trading and have hampered the global effort to combat climate change.  These entities, already facing the burden to invest in sustainability, now face the added and unfortunate challenge to ensure that the carbon they are dealing with is in fact legitimate.

The Reforest The Tropics Difference

Reforest The Tropics recognizes this challenge to buyers, and has committed to provide offsets of the highest quality and of the greatest transparency than any available. RTT has both its methodology and its calculations for its carbon capture audited by an independent forestry consultant every two years. RTT also offers Gold Standard verification of its carbon as required by its partners. Gold Standard carbon undergoes rigorous examination to ensure that it is accurately measured and reported.

RTT enhances transparency by individualizing projects for each forest sponsor.

RTT enhances transparency by individualizing projects for each forest sponsor.

Another mechanism to ensure carbon transparency is the individualized manner in which we operate. RTT tailors each project to a specific sponsor. Rather than the purchase of ‘pooled’ carbon from a large and ambiguous forest, RTT plants specifically for each sponsor. When a new forest is planted, the sponsor receives the GPS coordinates for the forest plot, and a large sign is installed to identify the sponsor and the details of the project. RTT sends photos and reports to each partner with the idea that sustainability initiatives will be most successful if emitters have an intimate connection to their project. Sponsors are even encouraged to visit their plots in order to experience their sustainability efforts firsthand. No other program offers this level of transparency for the carbon it captures.

The explosive growth of the carbon market is testament to the responsibility that buyers feel towards our environment. Although some will continue to seek the cheapest carbon credits available, they are risking an outcome that amounts to little more than empty bragging rights. Buyers that are seeking to make a true difference in the climate change equation are encouraged to seek carbon credits that they can see, measure, and touch with their own hands. RTT is proud to provide this option.

– Greg Powell, RTT Director

Excess CO2: The Elephant in the Room


When speaking with various stakeholders, we at Reforest The Tropics, often find ourselves talking about the “quality” of different carbon offsets. We maintain that all sustainability efforts are important and worthwhile, however the carbon offsets generated from tropical reforestation projects carry a special significance. Only carbon credits that are created from NEW forests are taking carbon dioxide out of the atmosphere. Offsets that are created through energy efficiency programs (think wind, solar, etc) or conservation programs (i.e. avoided deforestation, improved forest management) are only addressing the small yellow circle seen above. Of course, we need to shrink that circle to the extent that is possible, but we must not do so at the expense of ignoring the centuries of excess CO2 that has accumulated (represented by the checkered arc) in the atmosphere. This distinction is extremely important when we view the proportions of the carbon problem that we must tackle.

THERE ISForNewsletter HOPE… The diagram on the left demonstrates the importance of carbon extraction strategies. The planet shares the collective goal and responsibility to reduce atmospheric CO2 levels to approximately 745 Gt CO2 (or 350 parts per million). Currently, the atmosphere contains approximately 850 Gt (or 400 parts per million). Most climate change strategies are currently focusing on limiting the 10 Gt CO2 that are being emitted each year. Although carbon emissions reduction is very important, this graphic illustrates the relatively small impact these efforts have on the climate equation. Due to the longevity of CO2 in the atmosphere (500-800 years), we will never reach our sustainability goals without technologies that EXTRACT CO2 from the atmosphere. Tropical reforestation is our best hope to pull CO2 from the atmosphere and store it for the long term in trees, soil, and wood products. After 50 years of research, RTT models are extracting an average of 25 metric tons per hectare per year. Careful species selection and underplanting of shade tolerant species allows RTT forests to remain productive as carbon capturing tools for over 100 years. Our data indicates that RTT forests can accumulate over 2500 metric tons per hectare within 100 years. Some models have achieved this in only 50 years. Out of the estimated 185 million hectares of deforested land that is ideal for reforestation, we only need 40 million hectares using the RTT model.

Greg Powell, Director, RTT