Silvopastoral systems
Contents
1. Agroforestry system Tree Tree Rotation Firewood Annual Total carbon species density carbon sequestration ha years t ha sequestration t C ha t C ha a Shade trees Gliricidia sepium 330 30 101 4 0 7 51 6 Inga densiflora 400 20 42 8 0 5 24 3 Mimosa scabrella 650 2 18 3 2 0 24 9 Firewood plantations Leucaena leucocephala 3800 5 0 46 2 2 0 28 9 Eucalyptus saligna 1378 2 5 41 3 3 6 27 0 Secondary forests Miconia lonchophylla 3400 8 54 0 1 4 31 0 Lonchocarpus sp 7300 3 27 8 2 0 17 9 Lonchocarpus sp 3400 3 10 6 0 8 7 6 Cassia grandis 1700 3 21 2 1 6 12 3 Guazuma ulmifolia 2850 4 5 2 0 3 5 8 Trees in pastures Alnus acuminata 35 30 18 3 0 1 25 02. 1998 Malvaviscus Leaves 21 2 60 0 L pez et al 1994 arboreus amapola Young stems 9 3 65 0 Cratylia Comestible 20 0 55 2 51 0 33 9 Ibrahim et al 2000 c Cratylia argentea Total 23 8 51 8 52 0 34 4 Flores et al 1998 Cratylia Total NA 45 3 Valerio 1990 Guazuma Total 11 8 44 6 Herrera 1990 Ulmifolia caulote Total 11 0 43 8 52 0 34 4 Flores et al 1998 Gliricidia Total 24 3 67 4 41 0 25 1 Mochuitti 1995 sepium Total 23 2 64 7 43 0 L pez 1995 madero negro Total 27 2 54 3 53 3 32 7 Camero 1991 Leucaena Leaves 30 3 68 2 Hern ndez 1996 Leucocephala Young stems 18 5 46 9 leucaena Erythrina Total 27 2 54 4 Corado 1991 Poeppigiana Total 22 5 52 5 Herrera 1990 por Calliandra Total 18 0 22 0 Calothyrsus Total 30 3 34 0 55 4 24 3 Flores et al caliandra 1998 NDF neutral detergent fibre ADF acid detergent fibre Table 3 Effect of different levels of Morus alba mulberry on liveweight gains of steers fed a basal diet of Pennestum purpureum x P typhoides King grass source Gonzalez 1996 Variable Treatment mulberry kg DM 100 kg LW 0 1 1 9 2 8 Intake kg 100 kg LW Mulberry 0 00 0 90 1 71 2 11 King grass 2 04 1 79 1 29 0 95 Total intake 2 04c 2 69b 3 00a 3 06a 0 95a Liveweight gain kg an day 0 39c 0 69b 0 94a Means in the same row followed by the same letter are not significantly different Table 4 Accumulated dry matter production five cycles of harvesting of eight improved grasses grown in ful
3. arb reas de uso m ltiple en Gu piles Costa Rica Tesis Mag Sc Turrialba C R CATIE 145p Holmann F Romero F Montenegro J Chana C Oviedo E and Banos A 1992 Rentabilidad de los sistemas silvopastoriles con p quenos productores de leche en Costa Rica primera aproximaci n Turrialba 42 79 89 Houghton R A Skole D L and Lefkowitz D S 1991 Changes in the landscape of Latin America between 1850 and 1985 II Net release of CO2 to the atmosphere Forest Ecology and Management 38 173 199 Ibrahim M Franco F Pezo D Camero R and Araya J 2000 b Promoting intake of Cratylia argentea as a dry season supplement for cattle grazing Hyparrhenia rufa in the subhumid tropics Agroforestry Systems In press Ibrahim M and Schl nvoigt A 1999 Silvipastoral systems for degraded lands in the humid tropics Environmentally friendly silvipastoral alternatives for optimising productivity of livestock farms CATIE s experience In Actas IV Semana Cient fica del CATIE CATIE Turrialba Costa Rica 6 9 de abril 1999 pp 277 282 Semana Cient fica CATIE Ibrahim M Abarca S and Flores O 2000 a Geographical Synthesis of Data on Costa Rica Pastures and Their potential for Improvement Quantifying Sustainable Development The Future of Tropical Economies Edite en Hall C Academic Press U S A 423 448p Ibrahim M Canto G and Camero A 1998 Establishment and management of fodder banks for livestock feeding i
4. rufa grass Ibrahim et al 2000b The use of C argentea and sugar cane as supplement for dual purpose cows in the dry season resulted in daily milk yields of 5 to 6 5 kg cow day which is of much significance considering cows usually produce an average of 3 kg cow day in the dry season There has been only a few studies in Central America to determine the effect of grazing on the performance of fodder species Mochiuti 1995 made a detailed study to determine the effect of three grazing intensities 63 42 and 21 AU day ha on the persistence and productivity of Gliricidia sepium The data showed that high grazing intensities resulted in high stem mortality gt 18 and low yields but moderate grazing intensities did not significantly affect productivity of Gliricidia In another study Ibrahim et al 2000 noted that DM yields of Erythrina beteroana declined linearly in time gt 70 with frequent grazing every 3 months but high yields were sustained gt 3 5 tons ha every 4 months with a four month grazing interval The successful establishment of trees in pastures depends on the palatability of the species and level of physical damage caused to trees during grazing An experiment in the humid tropics of Costa Rica to determine grazing tolerance of trees Erythrina berteroana and G sepium sown in a silvipastoral system with Brachiaria brizantha showed that E berteroana tolerated high stocking rates 3 AU ha and it sustained high yiel
5. to improvements in soil N and P and higher soil moisture compared to the grass monoculture especially in the dry season Bolivar et al 1999 Velasco et al 1999 On more fertile soils the integration of multipurpose trees G sepium and E berteroana in B brizantha pastures did not show additional benefit in increasing pasture productivity when compared with mixtures of pastures with Arachis pintoi Esquivel et al 1998 although mixtures with E berteroana contributed to higher soil Mg Grazing of forest plantations e g Tectonia grandis to reduce risk of fires for weed control and short term generation of income was also studied In Turrialba Costa Rica the relationship between productivity of swards of Panicum maximum and stand density of Pinus caribaea were analysed by means of linear and non linear regression techniques comparing the following g potential predictors basal area Reineke stand density index canopy cover factor relative spacing index and biomass of leaves Gallo et al 1999 The results showed that the relationship between tree basal area x m ha and daily growth rate y kg MS ha day of P maximum gave the most reliable prediction of gross productivity y 28 76 1 08 x Environmental services of silvipastoral systems Generally incentive systems support pure forestry i e natural regeneration and forest plantation systems Agroforestry systems which combine elements of forestry and agricultur
6. 20 p Zelada E and Ibrahim M 1997 Tolerancia a la sombra de especies forrajeras herb ceas en el tr pico h medo de Costa Rica Archivos Latinoamericanos de Producci n Animal ALPA 5 42 44 Table 1 Abundance of trees by cattle production system La Fortuna San Carlos 1999 Average number of trees ha Trees Mixed Specialized in m lk Dual purpose n 24 production n 23 n23 Laurel 7 33 b 10 34 b 16 08 a Cedar 0 63 a 1 44 a 0 62 a Other timber trees 21a 4 33a 1 26a Non timber trees 1 99 b 6 00 a 2 51 b Total 12 46 a 22 11 b 20 47b Values with the same letter in the same row are not significantly different P 0 05 Lagarto sur gavil n and por Lim n dulce naranja guayaba guava and higuer n fruit and shade trees Table 2 Fodder quality of some woody leguminous and non leguminous perennials Species Fraction CP IVDMD NDF ADF Source Morus sp Total 15 8 63 9 50 0 28 5 Estrada 1997 mulberry Total 24 3 74 5 29 8 18 8 Flores et al 1998 Total 23 0 80 0 Benavides 1997 Total 145 60 8 Jim nez 1997 Leaves 20 3 74 4 Espinosa 1996 Young stems 11 8 67 0 Total 19 6 73 8 Leaves 19 1 81 1 Oviedo 1995 Young stems 60 6 Total 18 6 81 0 Leaves 20 0 77 0 Benavides 1994 Total 19 5 77 1 Trichanthera Total 19 9 67 4 40 7 33 9 Flores et al gigantea Nacedero 1998 Hibiscus Leaves 20 4 70 0 Rojas et al 1994 rosa sinenis Young stems 8 4 49 5 Clavel n Total 26 5 72 0 36 7 22 3 Flores et al
7. 2000 Multipurpose trees e g N fixing timber trees have the potential to rehabilitate these sites and provide economic viability of the production system On acid soils Acacia mangium has proven potential to increase the phosphorus and nitrogen content of the soil under pasture of Brachiaria humidicola Only on fertile soils silvipastoral systems with Brachiaria brizantha and multipurpose trees like Erythrina berteroana or Gliricidia sepium achieved similar nutrient levels as improved pastures with herbaceous legumes like Arachis pinto Esquivel et al 1998 For higher elevations which correspond to the dairy production the inclusion of Alnus acuminata in pastures has shown potential to restore soil fertility Russo 1990 NO3 N in pasture soils was four times higher under the canopies of Inga sp compared to open pasture and nitrification was five times higher for natural and laboratory incubation Rhoades et al 1998 The authors suggest that the increased soil N transformations under Inga are derived from improved soil rather than microenvironmental conditions A non N fixing species Psidium guajava didn t provide these services in the same study As valid for any production system the import and export of nutrients in silvipastoral systems needs to be monitored Cut and carry systems without fertilization may result into a negative nutrient balance and lead to soil degradation in silvipastoral systems Frequently the amount of nutrie
8. 98 Par metros nutricionales de algunas arb reas leguminosas y no leguminosas con potencial forrajero para la suplementaci n de rumiantes en el tr pico Livestock Research for Rural Development en prensa 8p Gallo L Somarriba E Ibrahim M and Galloway G 1999 Productividad de Panicum maximun bajo Pinus caribaea Agroforesteria en las Am ricas 6 57 59 Glover N ed 1989 Gliricidia production and use Nitrogen Fixing Tree Association NFTA Waimanalo USA Gonzalez J 1996 Evaluaci n de la calidad nutricional de la morera Morus sp fresca y ensilada con bovinos de engorde Tesis Mag Sc Turrialba C R CATIE 82p Harvey C 2000 Windbreaks enhance seed dispersal into agricultural landscapes in Monteverde Costa Rica Ecological Applications 10 155 173 Harvey C and Haber W 1999 Remnant trees and the conservation of biodiversity in Costa Rican pastures Agroforestry Systems 44 37 68 Harvey C Haber W A Mejias F and Solano R 1998 Remnant trees in Costa Rican pastures Tools for conservation Agroforestry Trees July September pp 7 9 Hernandez D Mirta C and Reyes F 1999 Establishment of a multi associated silvipastoral system Pastos y Forrajes 22 2 123 134 Hern ndez I 1996 Manejo de las podas de Leucaena leucocephala para la producci n de forraje en el per odo seco de Cuba Tesis Mag Sc Turrialba C R CATIE 83p Herrera M Z 1990 An lisis del comportamiento de 12 especies
9. MULTI STRATA SILVIPASTORAL SYSTEMS FOR INCREASING PRODUCTIVITY AND CONSERVATION OF NATURAL RESOURCES IN CENTRAL AMERICA Muhammad Ibrahim Andrea Schlonvoigt Juan Carlos Camargo and M Souza Summary Conversion of primary forest to pasture is widespread in Central and Latin America and the progressive removal of trees has resulted in environmental degradation and a decline in productivity simultaneously threatening rural livelihoods and regional biodiversity Recently there has been keen interest to develop silvipastoral systems for sustainable animal production Traditional silvipastoral systems are characterised with a diversity of woody perennials that plays an important role in supplying feed to animals in the dry season production of timber shade for animals and in the conservation of natural resources Improved novel woody perennials such as Morus alba mulberry and Trichanthera gigantea nacedero are characterised by high nutritive value and the use of these species as supplements for dairy and beef cattle resulted in significant improvements in animal production Studies on tree grass silvipastoral systems showed that the use of multi purpose trees such as Acacia mangium contributed to higher yields gt 30 of the associated grass and in improvements in soil quality These silvipastoral systems have been shown to sequester significant amounts of carbon 7 to 16 tons ha yr and they contribute in conservation of water resources
10. a similar range where 500 800 ha under sustainable forest or agroforestry management throughout the world would potentially sequester 0 5 1 5 Pg C a The amount of fixed C by trees depends on species characteristics like growth rate and longevity as well as site conditions like location climate rotation Table 5 Tropical forest plantations are the most effective in C sequestration Thus grazing of forest plantations or systems of natural regeneration of pioneer species like Cordia alliodora which form pure uniform stands will provide the highest increments Burger 1994 Forest plantations with pastures might sequester 25 50 Mg ha a Table 6 Other systems with low tree densities like live fences shelterbelts or dispersed trees are not that efficient 3 25 Mg ha a gt Silvipastoral systems can sequester carbon The efficiency of the system depends on the growth rate longevity and stand density of the tree species biomass production of the pasture species climate and soil conditions The most efficient systems are forest plantations which are used for grazing or fodder production Conservation of biodiversity In comparison to tropical forests extensive areas of pure pastures only provide habitats for very few species In the dry forest zone the pastures are managed with annual fires thus encouraging the sprouting of the pasture The few woody fire tolerant species with no productive use which germinate afte
11. ad nutritiva de Gliricidia sepium bajo defoliaci n manual y pastoreo en el tr pico h medo M Sc Thesis CATIE Turrialba Costa Rica 144 p Nair P K R Kang B T and Kass D C L 1995 Nutrient cycling and soil erosion control in agroforestry systems In Agriculture and environment bridging food production and environmental protection in developing countries Juo A S R ed ASA Special Publication 60 117 138 Oviedo F J 1995 Morera Morus sp en asocio con por y como suplemento para vacas lecheras en pastoreo Tesis Mag Sc Turrialba C R CATIE 87p Pezo D and Ibrahim M 1999 Modulo de ensefianza agroforestal N 2 Sistemas silvopastoriles 2 Ed Materiales de Ensefianza N 44 CATIE Turrialba Costa Rica 275 p Rhoades C Eckert G and Coleman D 1998 Effect of pasture trees on soil nitrogen and organic matter Implications for tropical Montane Forest Restoration Restoration ecology 6 3 262 270 Rhoades C 1995 Seasonal pattern of nitrogen mineralization and soil moisture beneath Faidherbia albida syn Acacia albida in Central Malawi Agroforestry Systems 29 133 145 Rojas H and Benavides J E 1994 Producci n de leche de cabras alimentadas con pasto y suplementadas con altos niveles de morera Morus sp In Benavides J Ed Arboles y Arbustos en Am rica Central Informe T cnico no 236 C R Turrialba CATIE p 305 320 Russo R O 1990 Evaluating Alnus acuminata as a component in agrofor
12. and biodiversity It is concluded that traditional systems are characterised with a diversity of woody perennials that have a significant value for improving animal productivity and for the conservation of natural resources Novel non leguminous woody perennials are of high nutritive value and has a great potential for substituting the use of concentrates in dairy and beef farming The selection and management of improved grasses and the management of woody perennials in silvipastoral systems can contribute in increased carrying capacities of pastures and thereby liberating fragile lands under grazing for re afforestation Introduction Conversion of primary forest to pasture is widespread in Central and Latin America and the progressive removal of trees has resulted in environmental degradation and a decline in productivity simultaneously threatening rural livelihoods and regional biodiversity Pezo and Ibrahim 1999 Szott et al 2000 Pasture covers more than nine million ha of Central America alone half of which is estimated to be degraded affecting the livelihoods of 10 million people Szott ef al 2000 Retaining and managing trees on pasture may improve farm productivity and sustainability by generating tree products and providing ecosystem services Ibrahim and Schlonvoigt 1999 Within fragmented forest landscapes farm trees may also represent critical habitats and corridors for plant and animal species that are important for maintaini
13. ds during the grazing period On the other hand G sepium was overgrazed and it disappeared in the pasture after the second grazing year Stem densities of G sepium declined linearly in time y 504 234x Abarca unpubl Tree pasture systems The integration of multipurpose tree shrubs in pastures are known to increase pasture DM yields and are involved in soil improvements Shade tolerant grasses Panicum maximum and B brizantha and legumes e g Arachis pintoi have been selected for these systems Zelada and Ibrahim 1997 Bustamente et al 1998 Experiences under humid conditions showed that improved grasses produced significantly higher DM yields in association with Erythrina poeppigiana multipurpose tree except some species Pennisetum purpureum cv Mott and B dictoyneura which had lower yields in mixed compared to pure stands grown in full sunlight Table 4 A high percentage of pastures are found on acid soils and the integration of fast growing multipurpose trees such as Acacia mangium with acid tolerant grasses e g Brachiaria humidicola has shown great potential for increasing productivity of these soils Velasco et al 2000 A study conducted on acid soils of Panama showed that DM yields of B humidicola was higher gt 30 in mixture with A mangium compared with the monoculture and the grass had higher crude protein in the mixture 3 vs 4 8 total biomass Higher DM yields of the silvipastoral system was associated
14. e are not considered The identification negotiation and sale of environmental services of these agroecosystems as part of the reforestation efforts is a major concern in today s development of sustainable production systems Aguirre 2000 The general hypothesis is that silvipastoral systems which are known as shelterbelts or living fences in pasture landscapes forest plantations with interplanted fodder or grazing fodder banks of woody and herbaceous species dispersed trees from natural or artificial regeneration on pastures do provide important environmental services which justify their consideration for forestry incentive programmes The following sections will analyse how silvipastoral systems provide environmental services in livestock farms Conservation of water resources The watersheds play the most important role in capturing the water resources At the watershed level the vegetation namely the forest ecosystems maintain the hydrological cycle Walling 1980 The cloud forests species are adapted to satisfy their water needs via interception of water from the clouds as they are generally swathed in clouds or mist Under normal rainfall conditions interception of precipitation by forest crowns reduces the amount of water which reaches the soil where conifers retain more water than angiosperms Short rainfalls or small raindrops are subject to high relative interception rates Trees affect water in several ways as barriers wh
15. eeing their future survival If the animals adopt the line plantings as habitat than these don t serve as corridors Schl nvoigt and Schl nvoigt 2000 In Monteverde 89 different bird species found their habitat in forest shelterbelts associated with pasture Harvey 2000 25 of a total of 400 plant species known for Monteverde regenerated in the shelterbelts Silvipastoral systems with dispersed trees hardly support the distribution of seeds especially those which are transported by wind because the regeneration on the extensive ranchlands is lost to trampling fire eating or weeding gt Silvipastoral systems can help to conserve biodiversity in fragmented agricultural landscapes The level of efficiency depends on the objective of the production system which design fits best to the farmers needs and how far this is compatible with the conservation aim The most promising systems are line plantings in the bests case connected with forest patches forest plantations and secondary forests with grazing Conclusions Traditional systems are characterised with a diversity of woody perennials that have a significant value for improving animal productivity and for the conservation of natural resources Novel non leguminous woody perennials are of high nutritive value and has a great potential for substituting the use of concentrates in dairy and beef farming The selection and management of improved grasses and woody perennials and their mana
16. estry systems Agroforestry Systems 10 241 252 Schl nvoigt M and Schl nvoigt A 2000 Planung und Einrichtung von Biokorridoren Planning and establishment of biocorredors In Naturschutz in Entwicklungsl ndern Neue Ans tze f r den Erhalt der biologischen Vielfalt Deutsche Gesellschaft f r technische Zusammenarbeit GTZ GmbH Bundesamt fur Naturschutz BfN Internationale Naturschutzakademie Insel Vilm eds Max Kasparek Verlag Germany pp 105 110 Sim n M Ibrahim MA Finegan B and Pezo D 1998 Efectos del pastoreo bovino sobre la regeneraci n de tres especies arb reas comerciales del Chaco Argentino Un m todo de protecci n Agroforesteria en las Am ricas 5 17 18 84 87 Souza de Abreu M Ibrahim M Harvey C and Jim nez F 2000 Caracterizaci n del componente arb reo en los sistemas ganaderos de La Fortuna de San Carlos Costa Rica Agroforester a en las Am ricas 7 26 53 56 Souza de Abreu M Ibrahim M and Silva de Sales J 1999 Arboles en pastizales y su influencia en la producci n de pasto y leche In Memorias de VI Seminario internacional sobre sistemas agropecuarios sostenibles CIPAV Cali Colombia CD Rom Szott L Ibrahim M and Beer J 2000 The Hamburger Connection Hangover Cattle pasture land degradation and alternative land use in Central Am rica CATIE DANIDA GTZ Trexler M C Haugen C 1995 Keeping it green evaluating tropical forestry strategies to mitigate global wa
17. et al 1999 Camargo et al 2000 Souza et al 2000 and in the highland regions where intensive dairying is practised there are good examples of planted and natural regeneration of Alnus acuminata in pastures Russo 1990 and Cupressus lusitanica wind breaks Harvey and Haber 1999 A case study conducted in San Carlos Costa Rica showed that dual purpose cattle farmers maintained a higher proportion of timber trees in pastures which is a good indication that these farmers minimised risk by diversifying production Table 1 Profitability of small Costa Rican dairy farms is increased especially when labour costs increase by diversification with high valued timber species such as C alliodora 2 188 vs 1 478 US farm yr for farms with and without the trees Holmann et al 1992 Cattle farmers may select timber species with small crowns e g C alliodora C odorata Albizia spp and Platymiscium pleiostachyum to reduce competition with grasses for light and to sustain high yields of animal products Harvey and Haber 1999 Souza et al 2000 Nicaraguan and Costa Rican cattle farmers may protect timber tree seedlings in pastures C Barrios pers comm 1999 but in one study in Costa Rica more than 60 of the damage observed on young timber trees was due to indiscriminate chopping and herbicide use Camargo et al 2000 Studies conducted in the Chaco region of Argentina also showed that grazing management is crucial to promote natural re
18. gement in silvipastoral systems can contribute in increased carrying capacities of pastures and thereby liberating fragile lands under grazing for re afforestation References Aguirre J A 2000 Cuencas hidrogr ficas servicios ambientales e incentivos para el desarrollo ganadero sostenible del tr pico Americano In Intensificaci n de la ganader a en Centroam rica beneficios econ micos y ambientales Pomareda C Steinfeld H eds CATIE FAO SIDE Turrialba Costa Rica pp 77 89 Barrios C Beer J and Ibrahim M 1999 Pastoreo regulado y bostas del ganado para la protecci n de pl ntulas de Pithecolobium saman en potreros Agroforester a en las Am ricas 623 63 68 Beer J Ibrahim M and Schlonvoight A 2000 Timber production in tropical agroforestry systems of Latin America In Forest and Society the role of research XXI IUFRO World Congress 2000 7 12 August 2000 Kuala Lumpur Malaysia Sub plenary sessions p 777 786 Benavides J 1994 La investigaci n en rboles forrajeros Jn Benavides J Ed Arboles y Arbustos en Am rica Central Informe T cnico no 236 C R Turrialba CATIE p 3 28 Benavides J Lachaux M and Fuentes M 1994 Efecto de la aplicaci n de estiercol de cabra en el suelo sobre la calidad y producci n de biomasa de morera Morus sp In Arboles y arbustos forrajeros en Am rica Central Benavides J E ed CATIE Serie T cnica Informe T cnico No 236 2 495 514 Bo
19. generation of valuable timber species Geoffroea decortican Schinopsis balansae and Prosopis nigra in pastures The percentage of tree damage decreased from 65 to 48 when pasture availability increased from 3 1 to 5 0 ton DM ha though some tree species were more tolerant of grazing Simon et al 1998 A high percentage of farmers gt 80 in Central America manage trees in pastures to provide shade for animals especially in the hot regions Harvey and Haber 1999 Souza et al 2000 Milk yields of dairy cows with access to tree shade were 20 higher compared to yields obtained from cows without shade Souza et al 1999 In many traditional systems in the seasonally dry pacific Pacific regions multipurpose trees e g Guazuma ulmifolia Brosimum alicastrum Pithecellobium saman and Enterlobium cyclocarpum produce fodder and fruits high in energy IVDMD 55 80 and crude protein 14 25 that are consumed by a animals Benavides 1994 Ibrahim et al 1998 A recent study in the dry pacific regions of Nicaragua showed that farmers maintained Acacia pennatula 30 40 adult trees ha in pastures because the fruits of this species supply feed to the animals in the dry season when yields of Hyparrenhia rufa fall Fruit yields of A pennatula varied between 28 and 35 kg tree Casasola 2000 A study is being conducted to evaluate the role of this species in conservation of biodiversity Current research trends in CATIE and the nationa
20. hanges account for a liberation of 30 Pg of carbon C to the atmosphere Houghton et al 1991 A significant contribution comes from the conversion of forests to pastures The carbon loss is related to the removed vegetation and the loss of soil organic matter Pasture species with a low biomass production Axonopus compressus lead to higher carbon emissions from the soil than high productive species like Brachiaria dictyoneura Veldkamp 1993 1994 The reverse conversion of pastures to silvipastoral systems e g forest plantations with grazing or fodder production natural regeneration of forest species on pastures may even further reduce the carbon loss from the soil A five year old plantation of Acacia mangium on an acid soil conserved higher organic matter in the soil than the pure pasture Camero et al 2000 On the other hand on a medium fertile alluvial soil a three to more than seven year old natural regeneration of C alliodora growing with P maximum obtained similar values of soil organic matter compared to pure pasture 180 200 Mg C ha Lopez et al 1999 The increase of the vegetation cover as the case in the conversion of pure pastures into silvipastoral systems increases the sequestered amount of carbon Winjum et al 1992 estimate that reforestation agroforestry and forest protection on 300 to 600 mill ha in the tropics would conserve and sequester 36 71 Pg of carbon for more than 50 years Dixon 1995 provides
21. ich control runoff as covers which reduce rain drop impact as soil improvers which increase infiltration and water retention Young 1997 Well managed pure pastures with low stocking rates which maintain a closed vegetation cover throughout the year are as well efficient in water collection as will be shown later Remnant trees and forest patches on the slopes improve water infiltration into the soil Gallery forests along the natural and artificial water channels stabilize these provide guided water transport to the rivers and reduce erosion Evapotranspiration rates are lower in pasture shade systems than pure pastures especially where these are exposed to strong winds This leads to higher soil moisture under the tree crowns compared to the open field With increasing tree age tree growth the positive impact on soil moisture may increase Rhoades 1995 In a watershed without any trees the impact of heavy tropical precipitations would be direct without any mitigation from the forest vegetation Under pasture with increasing animal stocking rates soil compaction increases leading to greater soil runoff At some stage severe soil erosion is the result leads to the sedimentation of rivers and sets an end to hydrological energy projects availability of potable and irrigation water Repeated events will lead to the degradation of the watershed Under these conditions the sustainable management of pasture systems should include forest componen
22. idia sepium Jacq Steud como suplemento proteicos para vacas lecheras alimentadas con heno de jaragu Hyparrhenia rufa Tesis Mag Sc Turrialba C R CATIE 92p Casasola F 2000 Productividad de los sistemas silvopastoriles tradicionales en Moropotente Estel Nicacagua 35 p In press Corado L H 1991 Efecto de cuatro niveles de pulidura de arroz sobre la producci n de leche de vacas en pastoreo suplementadas con follaje de por Erythrina poeppigiana Walpers O F Cook Tesis Mag Sc Turrialba C R CATIE 95p Dixon R K 1995 Agroforestry systems Sources or sinks of greenhouse gases Agroforestry systems 31 99 116 Espinosa E and Benavides B 1996 Efecto del sitio y nivel de fertilizaci n nitrogenada sobre la producci n y calidad de tres variedades de morera Morus alba L Agroforester a en las Am ricas 11 12 24 27 Esquivel J Ibrahim M Jim nez F and Pezo D 1998 Distribuci n de Nutrientes en el suelo en asociaciones de por Erythrina berteroana madero negro Gliricidia sepium o Arachis pintoi con Brachiaria brizantha Agroforester a en las Am ricas 5 17 18 39 43 Estrada X A 1997 Efecto de la sustituci n de King grass Pennisetum purpureum P thypoides por morera Morus sp sobre los par metros de degradaci n y fermentaci n ruminal de cuatro forrajes de calidad contrastante Tesis Mag Sc Turrialba C R CATIE 70p Flores O I Bolivar D Botero J A and Ibrahim M A 19
23. im et al 2000 c Some novel woody non leguminous woody fodder species such as mulberry Morus alba and nacedero Trichanthera gigantea are of higher nutritive value IVDMD gt 70 CP gt 14 than most leguminous woody perennials and can be used as substitutes for concentrates in intensive dairying Jimenez ef al 1998 Flores et al 1998 Mulberry requires fertile soils and adequate fertiliser management ie 300 kg N ha yr to sustain high DM yields of 12 to 16 tons edible DM ha yr Espinosa and Benavides 1996 In general the use of fodder trees as a supplement increased milk yields by 18 to 25 but the use of mulberry have resulted in greater increases gt 50 in milk production Ibrahim et al 1998 Ste rs fed mulberry as a supplement increased daily liveweight gains linearly from 0 39 to 0 95 kg animal as the level of mulberry offered increased from 0 to 2 8 kg 100 kg LW Table 3 In Central America and in Cuba there are good examples where commercial dairy farms are using mulberry as a supplement for dairy cows Ibrahim et al 1998 Hernandez et al 1999 Cratylia argentea a drought tolerant shrub has great potential for seasonally dry areas with marginal soils On farm studies conducted on hillsides of the Pacific region of Costa Rica showed that foliage of C argentea multipurpose species used as a dry season supplement for animal feeding resulted in significant improvements gt 30 in intake of dried Hyparrenhia
24. l agricultural research institutions are providing a better understanding of some of the more traditional agroforestry practices This is leading to the devel pment of new alternatives involving woody perennials for more productive and sustainable animal agricultural systems Moreover increasing timber prices provide important economic incentives to adopt silvipastoral systems Ibrahim et al 2000 a In addition to the forage fuel wood or timber qualities other characteristics of the tree and shrub species have to be considered in developing silvipastoral systems Research Advances Domestication of woody species Generally grass is the main feed source in traditional livestock production systems and livestock production is constrained by poor nutrition especially during the dry season when there is a severe shortage of feed on pastures Ibrahim et al 2000b There has been considerable research to evaluate woody forage perennials for their use as dry season supplements because many of these species e g Cratylia argentea Leucaena leucocephala Erythrina spp and Gliricidia sepium are more productive and have relatively high nutritive value Table 2 compared to tropical grasses e g Hyparrenhia rufa Ibrahim et al 1998 Ibrahim et al 2000 b Management of fodder trees and shrubs in high densities 20 000 to 40 000 plants ha with adequate prunning or grazing can result in production of 7 to 14 tons edible DM ha yr Benavides 1994 Ibrah
25. l sunlight and in association with Erythrina poeppigiana plantations pruned every six months Grasses With trees 1 Without trees Difference 1 2 2 Panicum maximum 20804 a 20791 b 43 16061 Panicum maximum 27780 a 24987 b 11 16051 Brachiaria brizantha 14437 a 10471 b 38 6780 Pennisetum 14343 b 16061 a 11 purpureum cv Mott Brachiaria 9787 a 8162 b 20 humidicola 6369 Brachiaria brizantha 8885 a 6175 b 44 664 Brachiaria 8393 b 9467 a 11 dictyoneura 6133 Cynodon nlemfuensis 6818 a 4490 b 52 Means in the same row followed by the same letter are not significantly different p 0 05 Table 5 Global estimates for potential carbon sequestration and conservation through different forest management practices for the period 1995 to 2050 adapted from Trexler and Haugen 1995 Climate zone Landuse Land surface Amount C sequestered or Costs Total costs practice 10 ha conserved Pg MgC 10 Tropical zones Reduce deforestation 138 2 22 Natural regeneration 217 2 22 Forest plantation 67 7 97 Agroforestry systems 63 5 27 Temperate zones Forest plantations 115 6 60 Agroforestry systems 5 5 3 Boreal zones Forest plantations 95 8 17 Total 700 59 9 248 estimates of minimum biomas includes 25 of C for roots litter and soil Table 6 Carbon storage in the above ground biomass of trees in some agroforestry systems in Central America adapted from Kiirsten and Burschel 1993
26. livar D Muhammad I Kass D Jim nez F and Camargo J C 1999 Productividad y Calidad forrajera de Brachiaria humidicola en monocultivo y en asocio con Acacia mangiun en un suelo cido en el tr pico h medo Agroforester a en las Am ricas 6 23 48 50 Burel 1996 Hedgerows and their role in agricultural landscapes Critical Reviews in Plant Sciences 15 pp 169 190 Burger D 1994 Reafforestation and other forestry CO strategies Plant Research and Development 4 pp 37 47 Bustamante J Ibrahim M and Beer J 1998 Evaluaci n agron mica de ocho gram neaas mejoradas en un sistema silvopastoril con por Erythrina poeppigiana en el tr pico h medo de Turrialba Agroforester a en las Am ricas 5 19 11 15 Camargo C Ibrahim M Somarriba E Finegan B and Current D 2000 Factores ecol gicos y socioecon micos que influyen en la regeneraci n natural de laurel Cordia alliodora en sistemas silvopastoriles del tr pico h medo y sub h medo de Costa Rica Agroforesteria en las Am ricas 7 26 46 52 Camero A Camargo J C Ibrahim M and Schl nvoigt A 2000 Agroforester a y sistemas de producci n animal en Am rica Central In Intensificaci n de la ganader a en Centroam rica beneficios econ micos y ambientales Pomareda C Steinfeld H eds CATIE FAO SIDE Turrialba Costa Rica pp 177 198 Camero L A 1991 Evaluaci n del por Erythrina poeppigiana Walpers O F Cook y madero negro Gliric
27. n Cayo In Ibrahim M and Beer J eds Agroforestry prototypes for Belize Serie T cnica Manual T cnico No 28 CATIE Turrialba Costa Rica pp 15 43 Ibrahim M Holman F Hern ndez M and Camero A 2000 c Contribution of Erythrina protein banks and rejected bananas for improving cattle production in the humid tropics Agroforestry Systems 49 245 254 Jim nez M Aguirre J Ibrahim M and Pezo D 1998 Efecto de la suplementacion con morera Morus alba en la ganancia de peso posdestete de terneras de lecheria pp Revista Agroforesteria en las Americas 5 17 18 23 28 Kirsten E and Burschel P 1993 CO mitigation by agroforestry Water Air and Soil Pollution 70 533 544 Lopez A Schl nvoigt A Ibrahim M Kleinn C and Kanninen M 1999 Cuantificaci n del carbono almacenado en el suelo de un sistema silvopastoril en la zona Atl ntica de Costa Rica Agroforester a en las Am ricas 6 51 53 Lopez G Z Benavides J E Kass M and Faustino J 1994 Efecto de la frecuencia de poda y la aplicaci n de esti rcol sobre la producci n de biomasa de amapola Malvaviscus arboreus n Benavides J Ed Arboles y Arbustos en Am rica Lopez S 1995 Evaluaci n de compuestos secundarios y consumo voluntario de cinco procedencias de Gliricidia sepium Jacq Walp en dos pocas del a o en el tr pico h medo de Costa Rica Tesis Mag Sc Turrialba C R CATIE 78p Mochiutti S 1995 Comportamiento agron mico y calid
28. ng local and regional biodiversity Harvey and Haber 1999 Systematic research is being conducted to evaluate silvipastoral options for improving animal production and for diversification of livestock farms Souza et al 2000 Recently farmers have become interested to manage trees in pasture because of their value in providing feed of a high nutritive value especially during the dry seasons and because of their economic value as timber carbon sequestration and conservation of biodiversity Harvey and Haber 1999 Souza et al 2000 This paper presents data on traditional and improved silvipastoral systems in relation to productivity and environmental services We hypothesised that silvipastoral systems are more productive and provide greater environmental services compared to traditional cattle production systems in Central America Traditional systems Most farming systems in Central America include some agroforestry practices that contribute partially to their economic and biotic sustainability but the densities and configuration of trees depend on cattle production systems Beer et al 2000 Souza et al 2000 Live fence post and agrosilvipastoral systems provide forage shade for animals and other benefits Valuable timber species such as Cedrella odorata Cedar Cordia alliodora laurel Pithecellobium saman and Albiza spp retained at low tree densities 4 to 15 trees ha are common in the tropical lowland pastures Barrios
29. nts captured by the trees are not sufficient to restore the nutrients lost by the exported yields Benavides ef al 1994 Silvipastoral systems which involve windbreaks reduce eolic erosion Nair et al 1995 On slopes live fences in contour lines reduce soil erosion especially in those areas where the pasture cover is lost or burnt by the end of the dry season and the soil is exposed to the rainfalls at the beginning of the rainy season Tree prunings applied as mulch reduce the kinetic energy of the raindrops on the soil particles Tree crowns also serve as a shield against heavy rainfalls and mitigate the impact of raindrop intensity Remnant trees and forest patches on the slopes are important barriers to soil erosion as long as they increase the water infiltration of the soil Otherwise single trees may even favour soil erosion when they present an obstacle on the slope which increases the velocity of running surface water and by this means initiate soil erosion around the tree base Glover 1989 gt Silvipastoral systems with multi purpose tree species do conserve soil resources on fertile soils and rehabilitate soil fertility on acid soils through improvements in soil organic matter biological nitrogen fixation and increased phosphor absorption Well designed live barriers control soil erosion on hill slopes while single trees can provoke the reverse Carbon sequestration In Latin America between 1850 and 1985 land use c
30. r the fire are generally eliminated manually in order to reduce competition with the pasture plants In these areas the diversity of plant and related animal species is decreasing continuously In the cloud forest zone of Monteverde Costa Rica 190 different forest species were identified on 240 ha of pasture which had been under dairy production for 30 years Harvey et al 1998 However the tree number per farm was very variable 7 90 trees farm as was the tree density 5 80 trees ha The trees had different utilities like shade for the cattle wood posts firewood shelterbelts or bird nutrition At first sight these trees seem to be a relevant contribution to the local biodiversity However a closer look at the natural regeneration showed that tree seedlings and young trees were very rare probably due to grazing and weeding of the pastures Without natural regeneration these silvipastoral systems will loose biodiversity as soon as the old trees die Silvipastoral systems are often identical with line plantings live fences or shelterbelts These systems are designed by man and modified in time by nature If they are used to connect forest patches they can serve as corredors to animals and plants Burel 1996 These corridors have the objective that the animals move from one patch to the other but don t adopt it as a habitat in order to achieve the genetic exchange between populations of fragmented patches thus guarant
31. rming World Resources Institute Washington DC USA 52 p Turcios W R 1995 Producci n y valoraci n econ mica del componente h drico y forestal de los robledales de altura bajo intervenciones silviculturales M Sc Thesis CATIE Turrialba Costa Rica 80 p Valerio S 1990 Efecto del secado y m todo de an lisis sobre la estimaci n de taninos y la relaci n de estos con la digestibilidad in vitro de algunos forrajes tropicales Tesis Mag Sc Turrialba C R CATIE 94p Velasco A Ibrahim M Kass D Jim nez F and Rivas G 1999 Concentraciones de f sforo en suelos bajo sistema silvopastoril de Acacia mangium con Brachiaria humidicola Agroforester a en las Am ricas 6 23 45 47 Veldkamp E 1993 Soil organic carbon dynamics in pastures established after deforestation in the humid tropics of Costa Rica Ph D thesis University of Wageningen NL 113 p Veldkamp E 1994 Organic carbon turnover in three tropical soils under pasture after deforestation American Journal of Soil Science Society 58 175 180 Walling E E 1980 Water in the catchment ecosystem In Water quality in catchment ecosystems J Wiley New York pp 1 47 Winjum J K Dixon R K and Schroeder P E 1992 Estimating the global potential of forest and agroforest management practices to sequester carbon Water Air and Soil Pollution 64 213 227 Young A 1997 Agroforestry systems for soil management 2nd ed CAB International New York USA 3
32. ts or alternate at least with forest fragments in order to sustain the productive basis for ecological and human needs However at the cloud forest level the situation might be different In Villa Mills Costa Rica at 2600 to 2800 masl a natural cloud forest with zero exploitation restored water resources at about 7600 m ha while the extraction of 20 or 30 of the basal stem area led to about 10500 and 9300 m ha respectively Turcios 1995 The higher values under exploitation are related to less interception rates 34 without any exploitation 24 or 25 with 20 or 30 explotation respectively A pasture in the same region managed at low stocking rates 0 5 and 0 6 Animal units preserved more water 12800 and 9800 m ha a respectively than the forest ecosystem Turcios 1995 which could be explained with the less interception of water from clouds which also is not lost to to the atmosphere but led to the soil due to the erect growth habit of the grasses which dominate pastures plant societies gt Silvipastoral systems can conserve water resources e g in watershed areas through increased water infiltration interception reduced erosion and evapotranspiration Pure pastures with low stocking rates might be superior in water collection at least in cloud forest zones Conservation of soil resources More than 35 of the pastures in Central America present signs of more or less advanced degradation Szott et al
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