Rainforestation farming: concept and history (Part I)

by Victor B. Asio, Dept of Soil Science, VSU

a) The concept

Rainforestation or Rainforestation farming is a concept of rehabilitating degraded lands or restoring forests using native forest tree species. It is based on the hypothesis that an ecosystem is more sustainable when its physical structure and species composition are closer to the local rainforest. The Rainforestation farming concept was first presented in seminars by the authors in 1992 and was first published in the peer-reviewed journal Annals of Tropical Research in 1994 (Milan and Margraf, 1994). Two years later a chapter on the Rainforestation concept appeared in the international book Dipterocarp Forest Ecosystems: Towards Sustainable Management by World Scientific (Margraf and Milan, 1996).

 

An idealized sketch of rainforestation about 15 years after its establishment (sketch by R. Dumalag)

The first demonstration sites in Baybay, Leyte were established in 1992. During the early iteration of the concept, spacing and line planting of the trees were considered which were then abandoned by Dr. Margraf because as he always stressed, “nature does not plant trees in straight lines”. Thus, he strongly advocated the random planting of the native trees to simulate a real rainforest. This random planting has thus become a fundamental principle behind the Rainforestation concept. According to the entropy law, the random distribution of tree species should mean more ecosystem stability.

In recent years, the concept has been promoted as a strategy to rehabilitate degraded lands in order to restore the tropical rainforests. In 2004, it was adopted as a national strategy when the Philippine Department of Environment and Natural Resources (DENR) Secretary Elisea G. Gozun through a Memorandum Circular 2004-06 ordered the integration of Rainforestation farming strategy in the development of open areas and denuded forests to promote biodiversity conservation and sustainable development in protected areas and other appropriate forest lands.

 

Photo of the first demonstration site in Mt Pangasugan about 10 years after the establishment

In 2006, the follow-up and monitoring research project funded by GTZ entitled “Rainforestation Farming: Alternative for Biodiversity Conservation and Forest Restoration” (P.P. Milan, M.J. Ceniza, V.B. Asio, S.B.Bulayog, and M. Napiza) was recognized by the Commission on Higher Education (CHED) as the Best Higher Education Institutes (HEI) Research Program. The project provided the needed scientific evidence that the concept was ecologically and economically feasible and now ready for wide-scale dissemination. 

b) Criticisms

From day 1, the concept has met severe and oftentimes unfair criticisms. The earliest criticism that hurt Dr. Margraf was the contention by critics including the ViSCA forestry professors that the originators (Dr. Margraf and Dr. Milan) were neither forest scientists nor vegetation scientists and thus they did not have the expertise to conceptualize a forest restoration strategy. Although valid to some extent, Dr. Margraf was aware of his knowledge limitations so he sought the advice of some of the most brilliant forest science experts in Germany and other countries. 

Another criticism from the agronomists was the use of crops under the “close canopy” demonstration site in that crops require full sunlight to produce yield. As a result, the field staff tried to use fruit trees but this was not very successful as well since the forest trees have the natural tendency to grow tall and cover the fruit trees below. Agroforestry specialists that visited the demonstration sites also consider the planting of crops and fruit trees in between forest trees as “just another variant of agroforestry”. 

Our CHED-PHERNET project site in Inopacan, Leyte, showing the successful 
establishment of the Rainforestation site although at a very high cost

Some forest science experts generally consider the assisted natural regeneration (ANR) as a better strategy to rehabilitate degraded lands because of its greater potential to rehabilitate vast areas of lands at a minimal cost. 

The project site shown in the previous photo in Inopacan, Leyte, appears just a tiny dot in the middle of the large degraded lands (above photo). The other large green patches are actually revegetated through the natural growth of shrubs and trees implying the potential of ANR. 

Lastly, there is a widespread notion that many landowners are only interested to adopt Rainforestation in order to plant hardwood native trees that they could harvest and earn high profits in the future. The fact that a few of the original demonstration sites for the concept established in 1994 have already been harvested by the landowners supports this apprehension. Thus, some people doubt whether this will eventually lead to long-term forest rehabilitation in the country. This should be a big challenge to the Institute of Tropical Ecology and Environmental Management (ITEEM) and other institutions promoting the concept.

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To cite this article: Asio, V.B. 2019. Rainforestation farming: concept and history. http: soil-environment blogspot.com. 

A peer-reviewed article on the history of Rainforestation can be downloaded from the Annals of Tropical Research

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The author (V.B. Asio) has been actively involved in the development and evaluation of the Rainforestation concept from the 1990s until the present. He was a member of the Project Management Core Group of the ViSCA-GTZ Applied Tropical Ecology Project, and later was the first Head of the Terrestrial Ecosystems Division of the Institute of Tropical Ecology. The Core Group members were Dr. M.J.C. Ceniza, Dr. B.B. Dargantes, Dr. R.C. Guarte, Dr. J.M. Quimio, Dr. B.P. Germano & Dr. V.B. Asio.

Anthropocene: The Human Age

Anthropocene is the term coined in 2000 by Paul Crutzen, the Nobel laureate from the Max Planck Institute for Chemistry, Mainz, Germany, to refer to the current geological epoch characterized by the global impact of human activity. The Anthropocene Working Group of the International Commission on Stratigraphy defines it as the present time interval, in which many geologically significant conditions and processes are profoundly altered by human activities (www.quaternary.stratigraphy.org). 

The conditions and processes include changes in: erosion and sediment transport associated with a variety of anthropogenic processes, including colonisation, agriculture, urbanisation and global warming; the chemical composition of the atmosphere, oceans and soils, with significant anthropogenic perturbations of the cycles of elements such as carbon, nitrogen, phosphorus and various metals; environmental conditions generated by these perturbations which include global warming, ocean acidification and spreading oceanic 'dead zones'; the biosphere both on land and in the sea, as a result of habitat loss, predation, species invasions and the physical and chemical changes noted above (www.quaternary.stratigraphy.org) 

According to a recent article in Nature Vol 519 (12 March 2015) by Richard Monastersky, momentum is building to establish a new geological epoch that recognizes humanity’s impact on the planet. But there is fierce debate among scientists whether or not to revise the Geologic Time Scale which is used by millions of people around the world, to accommodate the Anthropocene on top of the Holocene epoch (see scale below).

Source: www.serc.carleton.edu

One focus of the debate is the start of the new epoch. When did it actually began? Recent suggestions include 1610 and 1964. The 1610 suggestion is based on the dip in atmospheric carbon dioxide (measured from Antarctic ice cores) due to forest regeneration of huge areas of abandoned farmlands in Europe. The 1964 proposal is based on the high proportion of radioactive isotopes from the nuclear weapons testing (R. Gonzalez at www.io9com). But the Anthropocene Working Group considers the beginning of the 'Anthropocene' as c. 1800, around the beginning of the Industrial Revolution in Europe.

Once the proposal for an Anthropocene epoch is, after a long process, accepted by the International Union of Geological Sciences, the Quaternary period in the Geologic Time Scale above would consist of three (not anymore two) epochs: Pleistocene (2.6 mya to 12,000 yrs ago), Holocene (12,000 yrs ago to c. 1800) and Anthropocene (c. 1800 to present).

Methane emission from rice fields

Methane (CH4) and carbon dioxide (CO2) are the end products of carbon decomposition in rice fields and other wetlands. Methane, a major greenhouse gas, is the terminal step of the anaerobic breakdown of organic matter in wetland soils. It is exclusively produced by methanogenic bacteria that can metabolize only in the absence of free oxygen and at redox potentials below -150 mV (Neue et al. 1997).

According to the above-cited paper by Dr.H.U. Neue (former Head of the Soils Department at IRRI and later Professor of Soil Chemistry at the University of Halle-Wittenberg, Germany) one of the pioneers in methane research in rice fields, methane is largely produced by transmethylation of acetic acid and to some extent, by the reduction of carbon dioxide in wetland soils.

The rate and pattern of organic matter addition and decomposition also contribute to the rate and pattern of methane production. In rice field, methane production generally increases during the cropping season. Easily degradable soil carbon, plant litter, root exudates, decomposing roots and aquatic biomass that are added to the anaerobic zone of the paddy soil (this is the zone below the thin oxidized or brown soil surface) are the major carbon sources for methane production.

Presently, there is widespread research interest in the development of methods and strategies to reduce methane emission from rice fields and other wetlands. Some early studies have shown that sodium chloride at high concentration inhibits methane formation. Addition of sea water has also been found to inhibit methane formation at low salt concentration because of its sulfate content. Very recently, Dr. Roel R. Suralta and colleagues at Philrice, Nueva Ecija, have demonstrated that iron fertilizer application significantly reduced methane emission from rice field. More importantly, the iron fertilizer application also increased rice yield (Suralta et al., 2011).

References

Neue HU, JL Gaunt, ZP Wang, P Becker-Heidmann, and C Quijano. 1997. Carbon in tropical wetlands. Geoderma 79: 163-185.

Suralta RR, FS Gorospe, CA Asis Jr and K Inubushi. 2011. Effect of iron fertilizer application on the yield and methane emission of paddy rice field. In: Proceedings of the 14th Annual Meeting and Scientific Conference, Philippine Society of Soil Science and Technology (PSSST), VSU, Baybay, Leyte 25-27 May 2011, pp:95-96

Global warming and our local environmental problems

Global warming is the increase in the average global temperature. It is a real problem now and we are starting to experience its bad effects like the more frequent occurrence of strong typhoons, the warming of seawater resulting in decreased fish catch by fishermen, and the increased amount of rainfall resulting in catastrophic floods and landslides. It is predicted that the tropics where the Philippines is located will be most affected by global warming.

But apart from this global environmental problem, there are also serious local environmental problems that need urgent action. These include deforestation, land degradation, and soil and water pollution. Except for deforestation, these local problems have seldom grabbed the headlines and the endorsement of politicians and popular personalities hence most people are not well aware of the severity of these problems. But they are already threatening our lives and studies have indicated that these environmental problems may have already contributed to the loss of lives or have caused health problems of people.

The fact that much of the original or primary forest in most Philippine islands is now gone clearly indicates that we failed in protecting this vital natural resource. No need to cry over spilled milk says the popular expression. What we need to do is to see to it that the forest that remains is protected and the degraded uplands, the product of deforestation and kaingin in previous decades, are rehabilitated especially in critical watersheds across the country. A degraded land has reduced capacity to absorb rain so that much of the water during rainy days flow on the land surface resulting in floods and lowering of the water table (meaning, drying up of wells!). Degraded lands are also infertile and unproductive and thus are a threat to food security. Many of the poorest farmers are also living and farming in these marginal lands.

Soil and water pollution is largely caused by improper disposal of municipal solid wastes, the unregulated use of pesticides and fertilizers by farmers, and mining. Most towns in the country do not have proper dumpsites. Very disturbing is the fact that many municipalities use their mangrove areas (a vital breeding place for marine organisms) as dumpsites for solid municipal wastes. The unregulated use of pesticides and fertilizers by farmers also leads to soil and water pollution. You can easily notice this from the unusual vigorous growth of algae and aquatic plants around rice fields, ponds, rivers, and bays suggesting excess amount of nutrients from fertilizers and other sources. Mining is also a major cause of soil and water pollution. It is very unfortunate that more and more areas are opened to mining. The negative environmental effects of the Bagacay Mine which operated from 1954 to 1992 are still there. Recent major efforts to rehabilitate the site have not been successful.

One last thing: when you drink a glass of water, how do you know that it is not yet contaminated with harmful chemicals?

Photo source:
The global warming figure above was taken from the Renewable Energy Blog
http://www.solarpowerwindenergy.org

Could the alkaline soils of the world be the missing carbon sink?

The missing carbon sink is the large amount of unidentified carbon sink in the global carbon budget. According to the Woods Hole Research Center (2007) the average annual carbon emissions amount to 8.5 Pg (1 Pg or petagram is equal to 1 billion metric tonnes) comprising of 6.3 Pg from combustion of fossil fuels and 2.2 Pg from changes in land use. This is greater than the sum of the annual accumulation of carbon in the atmosphere (3.2 Pg) plus the annual uptake by the oceans (2.4 Pg) which is only 5.6 Pg. The difference of 2.9 Pg (i.e. 8.5-5.6=2.9) is unknown carbon sink required to balance the carbon budget.

Scientists have been searching for this big amount of unknown carbon sink during the last two decades. It was first thought to be located in the ocean considering that it occupies 70% of the earth’s surface. However, most scientists consider that the ocean sink is not big enough to account for the missing carbon (Xie et al., 2009). The next possible location is the world’s forest. In fact, many scientists believe that this large amount of missing carbon is absorbed by land-based carbon sinks particularly forests but estimates indicate that terrestrial ecosystems are a net sink of only 0.7 billion (Woods Hole Research Center, 2007). Some studies have revealed that carbon accumulation is largely counterbalanced by carbon loss from deforestation.

In a study published in Science, an international team of scientists led by Stephens (Stephens et al., 2007) revealed that the missing link may indeed be located in tropical ecosystems. They reported that northern terrestrial uptake of industrial carbon dioxide emissions is smaller than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for carbon dioxide. But whether or not this is enough to account for the missing carbon is not yet clear.

The third possible location of the missing carbon sink is the soil which is one of the largest dynamic carbon pools on earth. In a recent paper published in the journal Environmental Geology, researchers from China revealed a carbon sink which has been largely overlooked in the past. Xie et al. (2009) reported that alkaline soils (i.e. soils with pH > 7.0) on land are absorbing CO2 at a rate of 0.3-3.0 μmol m-2 s-1 with an inorganic, non-biological process. The intensity of this CO2 absorption is determined by the salinity, alkalinity, temperature and water content of the saline/alkaline soils. They estimated the range at 62-622 g C m-2 year-1. Considering that there are about 700 million hectares of alkaline soils around the world, the amount of CO2 absorption could be very significant on a global scale and could be a major part of the missing carbon sink.

References

Woods Hole Research Center. 2007. The missing carbon sink. http://www.whrc(carbon/missingc.htm

Stephens B.B. et al. 2007. Weak northern and strong tropical land carbon uptake from vertical profile of atmospheric CO2. Science 316: 1732-1735.

Xie J, Y Li, C Zhai, C Li and Z Lan. 2009. CO2 absorption by alkaline soils and its implication to the global carbon cycle. Environmental Geology 56: 953-961.