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Live Fence Posts in Costa Rica: A Compilation of the Farmer's Beliefs and TechnologiesGerard? Budow,ski Ricardo 0. Russo

ABSTRACT. Live fence posts are widely used in Costa Rica and other Cenhal American countries as a sustainable agricultural practice. The Costa Rican farmers' empirical knowledge was compiled through a questionnaire, field measurements and literature review. Ninety two species used for live fences were recorded and tabulated. The management practices (preparation of stakes,planting, attaching wire, pruning regimes) and the various uses are discussed. The biomass production of a kilometer of one live fence was measured. It is concluded that this is indeed a very promising sustainable practice which deserves more research and dissemination.INTRODUCTION

The construction and maintenance of agricultural fencing has the potential to become sustainable through the use of renewable resources. In Costa Rica, as well as in other tropical American countries, many fences or enclosures are constructed by stringing barbed wire on trees serving as fence posts. According to the diversity of climates and the corresponding life zones found in Costa Rica, a great variety of tree species are used for live fence posts (see Photo 1). They are usually propagated from large- -

Gerafdo Budowski is affiiated with the University for Peace, Program fm Natural Resources and Quality of Life, San Jos6, Costa Rica Russo is affiliated with Yale University, School of Forestry and Ricardo 0. Environmental Studies, New Haven, CT. Journal of Sustainable Agriculture, Vol. 3(2) 1993O 1993 by The Haworth Press, Inc. All rights reserved.

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cuttings or stakes (about 2-2.50 m). Each species has its own particular growth characteristics, cultivation requirements, management practices, derived products, and benefits. These trees may provide wood for fuel and charcoal or for construction (poles, posts, pillars, etc.), edible fruits and flowers, flowers for honey, leaf forage for cattle and other domestic mimals (e.g., goats, rabbits, and chickens), handicraft (seeds used for beads, ornamental wood), medicinal products, gums and resins, dyes as well as various other products. These plants also have great value as ornamentals and as a refuge for wild animals, notably birds. Additionally, they continually yield new cuttings for more fence posts. However, their main purpose is to serve as physical support to attach rows (usually 3, but their number may vary from 2 to 5) of barbed wire so as to effectively protect houses, crops, cattle and pastures or differenttypes of gardens. Furthermore,living fences provide conspicuous and fm boundaries to separate properties or areas within properties or pastures. When cuttings are planted very closely and sometimes associated with smaller plants that may be spiny (e.g., Bromelia pinguin), or poisonous (e.g., Euphorbia cotinifolia and Hura crepitans), they can also provide an effective barrier to cattle and people, even without use of barbed wire. Many other benefits and services are also provided. The leaves shed by live fences serve as mulch and release nutrients to adjacent crops. The periodic pollarding (cutting back the crown of the fence posts) results in starving and death of roots, leading to small air channels in the soil which favors water infiltration. Other benefits include nitrogen fixation by some species, specially legumes, erosion control and better infiltration of water, provision of shade, use as wind-breaks, niches for insecteating buds, support for orchids and ornamental plants and many other additional uses. A fair statement is that they have considerableaesthetic value. Whether as part of the landscape or from the beauty of their flowers and branching forms, live fence rows provide a pleasant break to the monotony of many grass-dominated landscapes. Many farmers, ranchers and rural laborers are experienced with the use of live-fence posts; some have well defined criteria concerning planting practices and the advantages and disadvantages of various species. But their knowledge is empirical and with the exceptionof a few species, such as Gliricidia sepium (Baggio, 1982; Beliard, 1984), this has not been quantified. The purpose of the present investigation is to overview present technologies and beliefs concerning live fence posts used in Costa Rica and to support obse~atiofl~ farmer interviews, some field measurewith ments, a literature review, and other experiences by the authors over the last 10 years.

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JOURNAL OF SUSTAINABLE AGRICULTURE

TRADITIONAL USES OF LIVE FENCES

Live fence posts have been recorded in the literature by many authors and travelers. While barrier and ornamental hedges had been employed traditionally by native people and by the Spaniards after the conquest of America, references are scanty, and the practice may not have been as common as it is today. It was not until the 19th Century that the use of living trees as fence posts came to be recognized particularly for use as a support to attach barbed wire. Early and continuing mention of some of the various species used is found in some treatises of economic plants, propagation and gardening books, and forestry manuals (Holdridge, 1970; Logsdon, 1978; Mintz, 1962). Most references on live fence posts species are found in some national or regional floras on the notes concerning utilization,or as short descriptivenotes inmanuals and books on ornarnental or commercial trees in the tropical American region (Duke, 1972) as well as in other regions of the world (Bond, 1944, Standley and Steyermark, 1946; Howes, 1946; Martinez, 1959). Several of the most common species such as Gliricidia sepium, Bursera simaruba and Spondiaspurpurea are now widely planted throughout the tropics. Moreover, several species of genera such as Erythrina are native to both the old and the new world where they are sometimes widely planted and the knowledge is often transferable. Gliricidia has been introduced to many countries, notably in South East Asia and lately in Africa where it is commonly planted for various purposes, although less frequently than in tropical America. In tropical Africa, for instance in Nigeria, it has become very popular as a live support for yams (Dioscorea spp.), but it has also other uses (Bond, 1944). Sumberg (1986) cites 143 references for Gliricidia sepium, some of them annotated, while at the Tropical Agricultural Center for Research and Training (CATIE) in Tunialba, Costa Rica, a bibliography concerning the genus Erythrina, widely used for fences has been compiled with about 500 references (Centro Agron6mico Tropical de hvestigaci6n y Enseiianza, 1986). Howes (1946), in one of the first reports specifically concerning live fences in the tropics, described and enumerated a variety of trees, shrubs and cacti used in or as fences for a diversity of purposes in Africa, India, Australia and New Zealand. Crane (1945) reported informal trials to select the most appropriate species for live fence posts. Specifically mentioned are Gliricidia sepium, Erythrina berteroana, E. poeppigiana, Bursera simaruba and others used at that time in Cuba. Burgos (1952) made recommendations as to species and practices in the humid lowland forest areas of eastern Peru. Allen (1977) recorded 7 species used for live fence posts in

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Southwest Costa Rica making a useful contribution toward elucidating the multiple purposes which live fence posts serve. At Tunialba, Costa Rica, many research theses are related to live fence posts. For instance, de Vastey (1962), included several live fence post species in an exploratory study to determine the possibilities of vegetative propagation of small cuttings using hormones. More related to the subject of fences, Lozano (1962) investigated improved methods for successful rooting of large cuttings from Gliricidia sepim, Erythrina costaricensis and E. poeppigiana. This author analyzed which species were best suited for different conditions, suggested better planting practices and emphasized seasonal timing for planting the cuttings. Budowski (1977) included live fence as a promising line of research for an international research program in agroforestry. Later, the author brought forth the various advantages and drawbacks of live fence posts over usual (dead) wooden posts (Budowski, 1982) and emphasized living fences in tropical America as a widespread agroforestry practice (Budowski, 1987). A more specfic paper on live fence posts used in Costa Rica was prepared by Sauer (1979). He listed 43 species including not only those planted by large cuttings,but also those that have been planted by seed or are allowed to grow from natural regeneration to serve as hedges or fences. He delineated their climatic boundaries and included various economics and historical notes and observations.Sauer made a strong plea to maintain diversity as part of the fence-post hedgerow complex.METHODSAn extensive literature review on species used for live fences in Costa

Rica was carried out at Orton Memorial Library, CATIE, Tumalba, Costa Rica. Species reported in at least one reference, were recorded and tabulated by scientificname, common name, family, life zone, uses and propagation procedures when possible. This data was compiled over a three year period. An informal questionnaire was used to int&view farmers who were particularly knowledgeable and experiencedwith living fences in different regions of the country. These interviews involved visits to the farms and conversationswith the fanners. Emphasis was placed on the number and frequency of species used in each region; thus some areas received more intensive scrutiny. Farmers were asked about their experiences, practices and observations concerning the l