CONSERVATION TILLAGE RELATED TO TROPICAL FOREST ISSUES
Patricia Negreros-Castillo1, Edgar Morales-Ortiz2, & Emily Mize3
1Iowa State University, Forestry Department. Ames Iowa.
2Research assistant, Felipe C. P. Quintana Roo, Mexico.
3Undergraduate student, Grinnell College
Corresponding author
Patricia Negreros-Castillo, Iowa State University, Forestry Department, Ames, Iowa 50011, Tel (515) 294-5708, Fax (515) 294-2995,
Key words: Mexico, secondary vegetation, slash and burn, multistrata
Summary
Conservation of natural resources in tropical regions tends to be more complicated than in temperate regions. In many cases, the use and management of tropical forest has resulted in the creation of large mosaics of secondary vegetation. Generally, secondary vegetation is considered of low economic value from the agricultural and forestry point of view. Secondary vegetation, however, has many currently untapped potential uses if allowed to reach maturity. One possibility for lengthening the fallow period is to find a way for farmers to cultivate some of their crops without completely clearing the forests. Thus, improving farming systems methods and productivity of crop land might be an approach to take advantage of this vegetation and maximize its potential. This paper is focused on the description of a multistrata agroforestry system designed to take advantage of secondary vegetation and maximize its potential. The system is known as the “Kampocolche system” (KS), a multi-strata agroforestry system developed with the input of local farmers and scientists.
Introduction
Conservation of natural resources in tropical regions tends to be more complicated than in temperate regions. Tropical ecosystems are more complex and less is known about them than temperate ecosystems. Too often development projects in tropical Mexico require the clearing of large forested areas to establish monoculture agriculture or cattle grazing projects [Sere and Lovell, 1992]. Many of these projects, however, have been unsuccessful and abandoned. Frequently, farmers use young secondary vegetation (not older than 12 years) for unproductive slash and burn agriculture. Consequently, the use and management of tropical forests has resulted in the creation of large mosaics of secondary forest. In Mexico from 18 to 24 million ha of forest are considered disturbed or secondary forests [Cairns et al 1995, Masera et al 1992]. In general, secondary vegetation is considered of low economic value from the agricultural and forestry point of view. Secondary vegetation, however, has many currently untapped potential uses if allowed to reach maturity. One possibility to lengthen the fallow period is to find a way for farmers to cultivate some of their crops without completely clearing the forests. Thus, improving farming systems methods and productivity of crop land might be an approach to take advantage of this vegetation and maximize its potential. This paper is focused on the description of a multistrata agroforestry system designed to take advantage of secondary vegetation and maximize its potential. The system is known as the “Kampocolche system” (KS), a multi-strata agroforestry system developed with the input of local farmers and scientists.
Materials and Methods
Site description
Quintana Roo is one of three Mexican states in the Yucatan peninsula (south eastern part of Mexico). The annual rainfall is between 1000 mm and 1350 mm, distributed unevenly with a 3-4 month dry period, and average annual temperatures of 25.9° [Tamayo, 1981]. The composition of the forest is the result of the precipitation regime, soil, hurricanes, fires, and the agricultural activities that have dominated the land since remote times [Gómez-Pompa et al., 1987]. Tropical forests in Quintana Roo are classified as tropical dry forest formation [Holdridge, 1947]. This study was carried out at Kampocolche, a Mayan community in central Quintana Roo, Mexico. Kampocolche is one of 20 “ejidos” (communities) that belong to the Mayan Forestry Community Organization of Quintana Roo. Kampocolche controls around 8000 ha of very disturbed forest. Currently the only product the farmers harvest for commercial purposes is poles used in rustic construction for nearby tourist centers. Approximately 115 families form the community, and their major activity is slash and burn agriculture.
Methods
The Kampocolche system is the result of a research project initiated in 1994 [Negreros-Castillo, 1994]. The main objective of the project focuses on tapping the potential uses of secondary vegetation through the application of agroforestry and agroecological principles. The project comprises the following stages:
1) Study of the species composition of secondary vegetation in three different types of soil and four different ages (2, 5, 8, and 12 years old). Carried out in 1994 [Negreros-Castillo et al., 1995]
2) Study of the agricultural crops suitable for cultivation at different light levels as a multistrata agroforesty system develops. Carried out during the Fall of 1997 [De Clerck and Negreros-Castillo, 1998].
3) Study of 10 very diverse and managed homegardens as models to develop agroforestry systems from secondary vegetation. Carried out during the Fall of 1997 [Morales, 1998].
4) Nutritional value of some suitable crops for multistrata agroforestry systems. Carried out during the spring of 1998 [Barrera & Negreros-Castillo, 1998].
5) Design and establishment of experimental multistrata agroforestry system. This stage of the project was initiated in January of 1998.
Development of the Kampocolche system
By applying agroforesty and agroecology principles [Gliessman et al., 1981; Torquebiau, 1992; Caron, 1995] and using the information obtained in stages one to four, a first design was developed. The first design was presented to the community and 5 farmers volunteered to participate in the research. The system was then explained in more detail and depth to these farmers. With the insightful input of farmers the original design was modified and a new one emerged (Fig. 1). Because the system was established in and with the collaboration of farmers from Kampocolche, it was named after the town’s name. Five repetitions of the Kampocolche system were established in March of 1998. The chosen sites are in an area of community land that was used for a cattle-grazing project from around 1980 until 1985. In 1980, 400 hectares of forest were cleared for cattle production. The project failed, and the land was abandoned in 1988. The land soon became overrun with secondary vegetation. Therefore, the secondary vegetation used in this experiment is 10-12 years old.
Results
The Kampocolche system is a multistrata agroforestry system designed to take advantage of secondary vegetation and maximize its potential. The system combines useful trees found in the secondary vegetation with crops and plants beneficial to the producers. The crops are harvested at different times during the year and are able to grow under different light conditions. The dimensions of the Kampolcolche system are 70x70 m. The system consists of four concentric areas of different sizes (Fig. 1).
1. Center zone: Annual crops.
Annual crops in the open. Crops using a method developed in northern Yucatan [Gordillo et al.; 1998], which allows for more years of cultivation than conventional methods. By lengthening the amount of time the field is cultivated, this lessens the need to rotate to a new field. The crop system uses chicken manure as a fertilizer in the first year and legumes in later years. The average production of corn from the five plots was 3.5 ton hectare compared with 0.5 ton per hectare obtained in the traditional slash and burn system.
2. Zone 1: Fruit trees + crops.
Seven different native fruit tree species (3 plants by species) (Table 1) were planted in a 5m wide strip around the center zone. The fruit tree seedlings have a height of about 50 cm. Between them 10 plants of tomato and 9 plants of hot pepper were planted.
Table 1. Fruit trees planted in the Kampocolche system.
Cayumito / Crisophyllum cainito L / SAPOTACEAECiruela Tuxpana / Spondias lutea L. / ANACEAE
Guanabana / Annona muricata L. / ANNONACEAE
Mamey / Pouteria mammosa (L.)Cronq. / SAPOTACEAE
Saramuyo / Annona squamosa L. / ANNONACEAE
Zapote / Manilkara zapota(L.)V.Royen / SAPOTACEAE
Anona / Annona reticulata L. / ANNONACEAE
3) Zone 2: Secondary vegetation + crops.
Secondary vegetation--this section surrounds the central and second zones of the plot. A quarter of the area (east) was thinned to plant six different types of crops underneath (Table 2). In the coming years, all the area will be planted with crops suitable for growing in this environment.
Table 2. Crops growing with secondary vegetation
Number / Name / Scientific name / Family1 / Chaya / Cnidoscolus chayamansa MC.Vaugh / EUPHORVIACEAE
2 / Chile / Capsicum spp. / SOLANACEAE
3 / Makal volador / Dioscorea bulbifera L. / DIOSCORACEAE
4 / Makal / Colocasia esculenta L. / DIOSCORACEAE
5 / Melocotón / Sicana odorifera Naud. / CUCURVITACEAE
6 / Nopal / Opuntia spp / CACTATACEAE
4) Zone 3. Tree enrichment.
In a strip of 5m right at the edge of the plot, valuable timber tree species were planted, at spacing of 5m (Table 3).
Table 3. High valuable timbers species planted around the plot.
Number / Name / Scientific name / Family1 / Caoba/mahogany / Swietenia macrophylla K / Meleaceae
2 / Cedro/Spanish cedar / Cedrela odorata / Meleaceae
2 / Sricote / Cordia dodecandra / Boraginaceae
Monitoring system
Several measurements are being taken at a regular basis:
1.- Soil fertilitybefore and after harvest
2.- Evaluation of the composition of the vegetation of the site
3.- Tree growth
4.- Crop production
5.- Labor (time and cost)
6.- Farmers understanding of the research and potential applications
Conclusions
Agroforestry systems are considered to function better than monocropping systems. With their many interacting parts, they are more akin to nature and its biodiversity. And, if the goal is to become more sustainable, modeling nature seems to be the most desirable option. However, experiments like this one still need to be carried out to determine the best way to imitate nature and also to provide quantitative evidence that agroforestry systems work. Del Amo and Ramos (1993) noted that we need more information on agroforestry systems to compete with the amount of information available on plantations, cash crops, and cattle farming. That is especially important in a country where the majority of farmers are poor and have a family depending on them. They cannot afford to take risks and change their way of farming without solid convincing evidence that the new system is more economical and efficient for them. That is the beauty of the Kampocolche system. It incorporates indigenous knowledge. It involves the people in the area because, ultimately, by deciding whether or not to implement the system in the future, they will be the ones judging whether or not the Kampocolche system is a success.
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Figure 1. Lay out of the Kampocolche multistrata agroforestry system.
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