Silvopastoral Systems in Latin America

 
 Ing. Agr. (PhD) Gustavo Alvaro Ferreira De Mattos
Director Regional
Instituto Nacional de  Investigación Agropecuaria (INIA)
Tacuarembó, Uruguay

 
Introduction
 

Silvopastoral systems are a deliberate combination of trees, pastures, and livestock (12). This combination allows a mixture of different quantities of these three components depending on the features of the ecosystem to be managed.
 

An ecosystem can be characterised as different populations of organisms interrelated in different ways among them and with the chemical and physical factors such as topography, latitude, altitude, sunlight, temperature, air humidity, rainfall, soil physical and chemical properties and climate (1).  That means the species and types of combination of the three components of silvopastoral systems will vary according to the ecosystem considered.
 

Human intervention in the ecosystem will produce changes in order to meet the desired objectives. According to the Millennium Ecosystems Assessment (4), in many parts of the world the consumption of ecosystems services are managed in an unsustainable way. Therefore it is strongly necessary to find direct drivers of ecosystem management that can provide more effective cost-benefit opportunities for multipurpose systems, which can meet multiple goals, including the pervasive environmental, social, and economic objectives of sustainable development.  
 

Latin America has 964 million ha of forests, comprising about 25% of the total forest area in the world (5). However, 7.5 million hectares per year are lost to deforestation, and it is necessary to find an alternative production system to avoid environmental damage. Most of this deforested land is used in extensive livestock production systems (6).
 

On the other hand, monoculture tree species in densely planted in rows and organised in large forest farms are criticised by several sectors of society. These strictly regimented plantations resulted mainly from different forest policies that were introduced in many countries in order to increase forests for timber and pulp production.  Their principal objective was to maximise wood production and financial benefits from the forest (7), ignoring other positive or negative externalities.
 

Silvopastoral systems represent an alternative production system that integrates tree production with livestock trying to take advantage of the synergy between them with beneficial effects for the environment, economy, and society.  The aim is to improve productivity in the short, medium and long term based on a bio-diverse ecological system that produces multiple products in a sustainable use of land.

Main Products of a Silvopastoral System 

 
Trees, pasture and livestock in a well managed in a silvopastoral system can produce several products in a sustainable manner. The objective of the systems varies according to the combination of the animal and forest products. For illustration, a summary of some of the main products is presented in Table 1.
 
 
Table 1. Main products of silvopastoral systems

 

Therefore, is clear the multiple contributions that silvopastoral systems can provide when well managed and by this way can contribute to the different dimensions of sustainable development.

Sustainable Silvopastoral Systems Management

A silvopastoral system is a complex system and therefore requires of wise management strategies to combine the different components in a balanced way. That means how to plant the trees, what kind of pasture will be managed and what type of animal. There are evidence in the literature that well managed the total production can be increased by the increase in livestock, pasture and forest production (8).  For example, almost all the plantation forest land in Uruguay has cattle grazing to reduce risks from fire and improve visibility and access (Figure 1).  More purposeful silvopastorile management is being examined now  in most countries in South America.

Figure 1.  Cattle grazing in Pinus taeda stand, Tacuarembo', Urugauy

Natural Pasture and Forest Management

Silvopastoral systems in Latin America are not a new concept, but vary considerably in the different countries.  According to Gallo (9, 17) in South America the following combinations among trees, pastures, and animals in native forests can be distinguished:
 

The Brazil "Caatinga" that means "white forest" or "white vegetation" in Tupi language it covers approximately 1,000,000 km² representing 10% of Brazil territory. It is mainly integrated for trees and woody shrubs such as Auxemma, Mimosa and Bauhinia that shed their leaves seasonally and grasses such as Brachiaria Mollis and different types of herbs. This is mainly used by small farmers with sheep and goats and also in very low stocking rate beef cattle. Some of the bushes and trees can also provide food for the animals during the drought season.
 

The “Chaco” forest located in the centre of Latin America (South of Brazil and Bolivia and North of Paraguay and Argentina) covers approximately 500.000 km² , and involves mainly woody shrubs and naive trees such as Erythrina falcate, Tipuana Tipu, Prosopis spp., and Schinopsis spp.asociated with grasses such as Aristida spp. Cloris virgata, and Setaria globulifera. Traditional livestock management overgrazes these systems causing problems for the pasture and the trees. Another problem is that today 2000 km² per year of the Chaco forest are reoriented to soybean.
 

Another ecosysytem known as The Espinal in Chile cover an area of approximately 20.000  km² and represent a complex and heterogeneous variety of silvopastoral systems that are source of food, energy and forage for the farmers living there. It is composed by herbaceous, such as Lolium Multiflorum, Briza Minor, Trifolium spp. and woody strata mainly of Acacia caven. Beef cattle, sheep and goats are mainly the animal component. High pressure of this natural resources had produced diverse degree of degradation and its sustainability is in risk (10). Those systems play an important role in the socioeconomics of this zone, and need to be improved in order to have more sustainable production systems.
 

Planted Silvopastoral Systems
 

Most of the forests planted in Latin America were of tree species with rapid growth and adaptability to the environment in order to obtain high quality wood, marketable timber (pulp and fibre) and other products like nuts or food for livestock, and lately environmental services (11, 12). Environmental services are the remuneration produced for society by the sustainable development of natural resources, in this case related with forests. However, even most commercial farms with single tree species densely planted in rows, approximately 25 to 35% of the land remains as natural grasslands (wet lands, fire protection, pathways, etc.). Therefore, one of the challenges of these silvopastoral systems is how to increase pasture and livestock production within the already planted trees. Different research has shown that it is possible to obtain internal rates of return between 14% to 25%, and obtain attractive NPV showing the profitability of the system (14, 15).
 

The main tree species planted are mainly Eucalyptus spp., Pinus spp., Araucaria spp., Nothofagus spp., and Populus sp. The pasture depending on the part of Latin America can be Bracchiaria spp., Setaria spp.,  Paspalum spp., Axonopus spp., Penisetum spp., Digitaria, spp. Etc. Livestock are mainly cattle and sheep and it is necessary to select a biotype adapted to the conditions. Photo 1 shows a Brahma crossbreeding grazing in Eucalyptus grandis Forest.  Photo 2 shows Aberdeen Angus and Brahma crossbreeds grazing in a Pinus Forest.

Prospects for the Future

There is a large opportunity in Latin America to develop silvopastoral systems that can be profitable, biodiverse, and environmentally and socially compatible (16). The challenge is to develop research that can support the improvement and efficiency of those systems and to generate capacity building that can implement those required changes.

Bibliography

(1) M. Lynne Corn (1993) Ecosystems, Biomes, and Watersheds:Definitions and Use. Environment and Natural Resources Policy Division (Congressional Research Service  July 14, 2006 1993,93-655 ENR

(2) Sotomayor G. A., (1988). Silvopastoral Systems with Commercial Trees. Agro forestry. FRSC/RASC.  689, Forest Science Department, Texas A&M University, 1988.

(3) International Institute of Tropical Agriculture (IITA)
 
(4) Millennium Ecosystem Assessment, 2005, Ecosystems and Human Well-being: Synthesis. Island Press, Washington, DC.
 
(5) FAO.  2003.  State of the World’s Forests, 2003.  Food and Agriculture Organization of the United Nations.  Rome.  151 p.
 
(6) FAO Livestock Policy Brief 03, Livestock Information, Sector Analysis and Policy Branch, FAO.
 
(7) A walk through the Forest By: K.J.W. Oosthoek. Environmental History Resources,http://www.eh-resources.org/walk.html
 
(8) Herschel Fike, J.; Leonore Burgler, A., Burger, J.A., Kallenbach, R. L. Considerations for Establishing and Managing Silvopastures. Plant Management Network. November 2004.
 
(9) Gallo, L.. Silvopastoralism with native tree species in Uruguay In: M.R. Mosquera and A Rigeiro Rodriguez (Ed.) Procedeengs of an International Congress on Silvopastoralism and Sustainable Management. pp. 49-50.
 
(10) Muñoz, C., Zagal, E., and Ovalle, C.  Changes in Soil Organic Matter in the Espinal Agroecosytem of Central Chile with Different Covers of the Legume Tree Acacia caven (Mol). http://www.ecologicalrestoration.net/archivos/Munoz,%20C.V.doc.

(11) Agroforestry Note 8 "Silvopasture: An Agroforestry Practice" http://www.unl.edu/nac/afnote8.htm.

(12) Agroforestry Note 9 "The Biology of Silvopastoralism" http://www.unl.edu/nac/afnote9.htm.

(13) Agro Guides. Federation of British Columbia http://www.woodlot.bc.ca/swp/agro/docs/AgroGuideChapter04.pdf
 
(14) Plevich J O, Vita A, Julio G and L. Gonzalez. Ordination for energy and forage objectives. Case study for an agricultural community in the dry zone of Chile. http://www.fao.org/WAIRDOCS/LEAD/X6109E/x6109e0c.htm.
 
(15) Yvette A., Muhammad I., Potential of silvopastoral systems for economic dairy production in Cayo, Belize and constraints for their adoption. http://www.fao.org/WAIRDOCS/LEAD/X6109E/x6109e0c.htm.
 
(16) Stoian, D., and Current, D. Importance of Silvopastoral systems in rural poverty alleviation and sustainable resource management: insights from a livelihoods perspective. In: Mannetje, L., Ramirez, L., Ibrahim, I., Sandoval, C., Ojeda, N. and Ku, j. (eds) The Importance of Silvopastoral Systems in Rural Livlihoods to provide ecosystems services. Proceedings Supplement of the 2^nd International Symposium on Silvopastoral Systems. Cultural Center of the Autonomous University of Yucatán, Mérida, México. 2004.
 
(17) Gallo, L. Manejo Integrado de Ecosistemas y Recursos Naturales en Uruguay, 2004 y Presentación Taller sobre Silvopastoreo, INIA Tacuarembó Mayo 2005, Tacuarembo Uruguay. http://www.mgap.gub.uy/UPCT/DiagnósticoSilvopastoreo.pdf

 Posted: August 2006

Updated: 22 April 2007