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.

The geoecology of the limestone and shale areas in Samar, Philippines

Contributed by

Dr. Ian A. Navarrete
Humboldt Fellow
Soil Science of Tropical and Subtropical Ecosystems
Buesgen Institute
University of Göttingen, Germany

Geoecology, a term coined some 41 years ago by the geomorphologist Carl Troll who was at the time professor at the University of Bonn, Germany, is a broad integrative term to the study of forms and functions of terrestrial geoecosystem (Huggett, 1995). It emphasizes the interdependency and/or inter-relationships of the ecological biosphere with landscape and hence sometimes equated with landscape ecology. For example, the movement and distribution of solutes across soil landscapes are influenced by the geomorphic position in the soil within the landscape thus influencing soil genesis (Sommer and Schlichting, 1997) and vegetation development (Huggett, 1975). 

Fig 1. Relation of primary forest and grasslands of Samar

During our fieldwork at the Samar Island Natural Park (along the Paranas-Taft road at about 300 m above sea level) in Feb 2012, we observed two typical grassland ecosystems occurring near or far from the primary forests (Fig 1A).

The first type is the grassland that occurs in the lower residual limestone soil or at the margin of the primary forest. The soils in such grassland are younger as indicated by poor soil profile development. The dominant grass is Paspalum conjugatum which in many areas occur in association with Chromolaena odorata. The second type is the grassland in the degraded rolling and hilly areas usually away from primary forests. The soils in these areas are different from the soils in the primary forest on the upper slopes in that they are mature, reddish, and deep (Fig 1B). They appear to have formed from the limestone residue or from the shale (underlying the limestone) that is widely exposed in the rolling areas. The dominant grass is Imperata cylindrica. 

Fig 2. Primary forest soil in Samar

The soils of the primary forest (limestone forest) on the upper and usually steep slopes are generally very thin and are underlain by consolidated limestone rocks (Fig 2). The presence of nutrient-enriched weathering pockets (where deposition of nutrient and decomposition of organic matter take place) of the limestone parent material, and the high annual rainfall explain the lush growth of the forest vegetation. It also partly explains the high tree species diversity of the forest.

(Members of the team: V.B. Asio, Ariel Bolledo, Mark Moreno, Pearl Carnice, Richel Lupos, Forester Elpidio Cabahit Jr. from the Samar Island Natural Park, and myself)

References

Huggett RJ (1975). Soil landscape systems: a model of soil genesis. Geoderma 13: 1-22.
Huggett RJ (1995). Geoecology: An Evolutionary Approach. Routledge, London.
Sommer M, Schlichting E (1997). Archetypes of catenas in respect to matter-a concept for
structuring and grouping catenas. Geoderma 76:1-33.

Ethnopedology: the study of local soil knowledge

“There is a need to integrate science and local knowledge. Both are vital and can be brought together only by participation” emphasized Prof. Dr. Franz Heidhues in his concluding remarks during the International Scientific Conference on Sustainable Land Use and Rural Development in Mountain Areas held at the University of Hohenheim, Germany on 16-18 April 2012. As can be seen from the figure below, scientific knowledge becomes more relevant when it is combined with local knowledge (Barrios and Trejo, 2003).

Precision & relevance of scientific and local knowledge  

Ethnopedology is the study of the local knowledge on soil and land systems of rural populations, from the most traditional to the modern. Ethnopedological research covers a wide diversity of topics centered around four main issues: (1) the formalization of local soil and land knowledge into classification schemes; (2) the comparison of local and technical soil classifications; (3) the analysis of local land evaluation systems; and (4) the assessment of agro-ecological management practices (Barrera-Bassols and Zinck, 2003; Barrios and Trejo, 2003). It encompasses many aspects, including indigenous perceptions and explanations of soil properties and soil processes, soil classifications, soil management, and knowledge of soil–plant interrelationships (Talawar, 1996).

In a recent study conducted in Vietnam and Thailand and presented in the above-mentioned scientific conference in Hohenheim, Dr. Gerhard Clemens and co-workers found, among other things, that: 1) Farmers classify their soils first of all according to soil color; 2) Farmers are able to describe soil properties and features. They also know the local factors affecting their soil; 3) Local soil classification is not consistent but the predominant soils can be efficiently identified using local soil knowledge.

An old farmer sharing some traditional knowledge 

Our own research in the degraded lands of Parasanon, Pinabacdao, Samar showed that the sweetpotato farmers possess a local knowledge system with regards to the nature of the soil and that of their sweetpotato crop. The demographic traits of the farmers clearly differed but they adhered to the same knowledge system regarding the attributes of the soil in their locality and the growth condition of their sweetpotato plants. Using their native dialect, the farmers have a soil classification scheme based on textural characteristics; they have also certain indicators of soil fertility and plant health. Moreover, the farmers know of certain problems concerning their soil or crop but they are not detracted by these because of their experience in finding ways to circumvent the situation (Pardales et al., 2001).

There has been an increasing research interest in local soil knowledge in recent years. This is the result of a greater recognition that the knowledge of people who have been interacting with their soils for a long time can offer many insights about the sustainable management of tropical soils (Barrios and Trejo, 2003).

References

Barrios E and MT Trejo. 2003. Geoderma 111: 217-231
Barrera-Bassols N and JA Zinck 2003. Geoderma 111: 171-195
Clemens G, U Schuler, BL Vinh, H Hagel, and K Stahr. 2012. International Scientific Conference on Sustainable land use and Rural Development in Mountainous Areas, University of Hohenheim, Stuttgart, 16-18 April 2012
Heidhues F. 2012. Conclusions. International Scientific Conference on Sustainable land use and Rural Development in Mountainous Areas, University of Hohenheim, Stuttgart, 16-18 April 2012.
Pardales JR, VB Asio, AB Tulin and DM Campilan. 2001. Project Report, UPWARD-CIP, Laguna.
Talawar, S., 1996. Research paper #2.Department of Anthropology, University of Georgia, Athens, USA.

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

Soil degradation in the Philippines

Soil degradation is a severe global problem of modern times. About six (6) million hectares of agricultural land worldwide become unproductive every year due to the various soil degradation processes. The problem is much more serious in tropical than in temperate areas since tropical soils are generally more prone to degradation because of the nature of their properties (e.g. they are more weathered) and the prevalent climatic conditions. Countries in Asia and Africa that depend upon agriculture as the engine of economic growth are believed to suffer the greatest impact of soil degradation. In the Philippines, soil degradation is one of the most serious ecological problems today. The National Action Plan (NAP) for 2004 to 2010 identified soil degradation as a major threat to food security in the country. NAP reported that about 5.2 million hectares are seriously degraded resulting in a 30 to 50% reduction in soil productivity.

A degraded upland in Leyte

Soil degradation is defined as the process which lowers the current or future capacity of the soil to produce goods or services. It implies a long-term decline in soil productivity and its environment-moderating capacity. The concept of soil degradation was first used by Kostychiev and Korchinski in 1888 to describe a natural soil change. Since natural degradation is slow, the present concept of soil degradation according to the Global Assessment of Soil Degradation (GLASOD) focuses on a human-induced process. Soil degradation occurs because of drastic changes or disruption in the normal processes of soil formation due to human activities.

A degraded upland covered with Imperata (cogon) grass in Samar

In a review paper on the problem of soil degradation in the Philippines published in the Annals of Tropical Research vol. 31, we (Asio et al. 2009) revealed that soil erosion is the most widespread process of soil degradation and is also the most studied in the country. Other important but less studied soil degradation processes include loss of nutrients and organic matter, salinization, acidification, pollution, compaction, and subsidence. 

A degraded upland in Bukidnon

Studies reviewed have shown that the widespread degraded upland soils possess chemical and physical constraints for crop growth like acidic or calcareous pH, low organic matter and nutrient contents, shallow solum, presence of toxic substances, and compaction. The major factors that cause soil degradation include deforestation, overgrazing, agricultural practices, industrial activities, mining, and waste disposal. Deforestation is the main cause of soil degradation in Asia and South America while overgrazing is the main factor in the dryland areas of Australia, Africa, Europe, and Asia.

The typical degraded land in Cagayan Valley due to deforestation & overgrazing 

There is a need for more data on the physical and socio-economic characteristics of degraded lands to aid in the formulation of appropriate soil management strategies to support biodiesel production in these unproductive lands which are now being promoted by the Philippine government. Also, there is the danger that the use of the degraded lands for intensive and long-term biodiesel production without the appropriate soil management would cause further soil deterioration and thus aggravate the ecological problems that are now occurring.

Reference

Asio VB, Jahn R, Perez FO, Navarrete IA, and Abit SM Jr. 2009. A review of soil degradation in the Philippines. Annals of Tropical Research 31: 69-94

Note: All photos are owned by the author.

Is soil science in an upswing?

In many countries, soil science has been traditionally associated with agriculture because of the major function of soil as a medium for plant growth. So it was no surprise that the decline in funding for agricultural research worldwide in the last two decades had taken its toll on student enrolment in agricultural sciences including soil science. But there are good signs that soil science is now experiencing an upswing particularly because of its strong link to environmental management and global warming (soil is a major source and sink of carbon) and to recent increased focus on agriculture.

In a recent paper published in Geoderma, Dr. Alfred E. Hartemink of ISRIC in Wageningen, Netherlands, and Prof. Alex McBratney (University of Sydney) think that soil science renaissance (from French word meaning "rebirth") is currentyl taking place "where novel approaches to thought are combined with a revival of ideas from the past." They noted that renewed interest in food, feed, and fuel production and the publication of numerous reports have brought soils back onto the global research agenda.

Recent reports by the United Nations and other international organizations have highlighted the need for up-to-date and fine resolution soil information and the revival of soil research. They cited as examples of key issues that have been discussed in recent publications soil erosion, nutrient depletion, and pollution particularly in relation to environmental degradation, climate change, and world food production. They estimated that about 3.2 billion euro is spent yearly on soil research worldwide. They urge the soil science community to benefit from the current upsurge in soil science.

Reference

Hartemink AE and A McBratney. 2008. A soil science renaissance. Geoderma 148: 123-129.

Functions of soil

Soil is not dirt. It is a vital life-support system for human survival. Below are the major functions of soil:

a) Production function. Soil acts primarily as a medium for the growth of natural vegetation and cultivated plants. It assures the supply of food, fodder, renewable energy and raw materials. This is also referred to as the forestry and agricultural function of the soil.

b) Ecological regulator. Soil acts as filter, buffer, and transformer of various substances in or that are added to the soil. As a filter, the soil cleans polluted waters that move through it. As a buffer, it resists sudden change in its chemical balance thereby protecting the plants and soil organisms living in it. As a transformer, the soil is able to transform substances through microbiological and biochemical processes. The latter function is vital to the cycling of elements, degradation of toxic substances, decomposition of organic matter and production of greenhouse gases.

c) Habitat and living space. Soil is a habitat for a multitude of flora and fauna which are vital for human life. The largest quantity of organisms on Earth is in the soil. Many of the important antibiotics to treat human diseases are products of soil bacteria. Thus soil management is directly linked to the question of biodiversity. Soil also provides living space for humans and foundation for indrastructure such as roads, buildings, airports and others. Many human illnesses today are caused by soil pollutants that enter the food chain or enter the body through ingestion or inhalation.

d) Cultural heritage. Soil conceals and preserves remnants of past civilizations and plant and animal life. These paleontological and archaeological materials are of great value for the understanding of the history of civilization and the history of Earth.

Soil science is a natural science

Soil science or pedology (pedo is Greek for ground or soil) is a scientific discipline at the meeting point of physical, biological, geological and agricultural sciences. Because soil is a natural body, soil science is a natural science that deals with the study of soil in all its aspects such as genesis, composition, properties, geography, ecology, fertility, degradation and protection. A more specific definition states that soil science is an environmental (or ecological) natural science concerned with the evolution, characterization, function, distribution, management and protection of the soil resource in terrestrial ecosystems.