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Paraguay is entirely within the upper watershed that drains southward to become La Plata River. The Paraguay River begins north of the country in the pantanal wetlands and bisects Paraguay into distinct natural regions: to the west are vast alluvial plains of the drier chaco (264,925 km²) (CPD Site SA22); to the east is more humid, geologically varied terrain (159,827 km²), commonly called Paraguay Oriental (Eastern Paraguay).
Eastern Paraguay is bounded by the Apa River to the north, the Amambay-Mbaracayú mountain ranges to the north-east and the Paraná River to the east and south, and is subdivided into two fairly distinctive areas by a series of low (300-860 m) rolling hills and mountain chains which form an S-shaped watershed from the Sierra de San Joaquín and Cordillera de Ybytyruzú southward to the Cordillera de San Rafael. East of the watershed is the Paraná Plateau; to the west opens a broad undulating plain which gradually descends south-westward to become the immense Neembucú wetlands. The Mbaracayú Reserve is mostly south-west of the Cordillera de Mbaracayú, in north-central Canindeyú Department (Map 54).
Eastern Paraguay is largely underlain by Triassic basaltic lava which has given rise to red-brown lateritic or very dark colluvial and hydromorphic soils, and Precarboniferous sandstone where red-yellow sandy podzols prevail. The region's annual rainfall averages 1600-1800 mm. The rainy season extends from October to March, and July and August are driest. The mean annual temperature is 20°-25°C, with extreme highs near 40°C and lows c. 0°C although frost is infrequent and limited to early mornings. There is distinct biseasonality, with hot humid summers and cool less humid winters (IIED, STP and USAID 1985).
Eastern Paraguay was once covered with extensive forests (picture) (Zardini 1993). The remnants are some of the continent's last larger subtropical moist forests. Semi-deciduous, they harbour several endemic subtropical genera, and some tropical and cerrado species in the southern extreme of their ranges. These forests are also phytogeographically intriguing because of the intermingled taxa with tropical and temperate affinities. An inventory of the flora and fauna of Mbaracayú was conducted in 1989-1990 using the procedure of Rapid Ecological Assessment (TNC 1992) to identify the natural communities and assess their natural status; 19 plant communities were recognized (CDC-Paraguay 1991).
The reserve harbours several types of forest. Non-flooded climax forest covers c. 87% of the area and reaches 15-30 m in height. Bignoniaceae, Leguminosae and Meliaceae are dominant. There are two tree strata and some canopy trees are deciduous. Emergents include Tabebuia heptaphylla, Cedrela fissilis, Balfourodendron riedelianum, Piptadenia rigida and Peltophorum dubium; understorey trees include Sorocea bonplandii, Guarea kunthiana and Pilocarpus pennatifolius. Epiphytes occur, and lianas are notably important their density of 92 individuals per 0.1 ha is one of the highest reported for the neotropics (Keel, Gentry and Spinzi 1993).
The climax forest grades into riverine or flooded forests in wetter areas. Bambusa guadua (= Guadua angustifolia) can be important in these wetter habitats, forming dense and often nearly pure stands. Riverbanks are often dominated by Luehea divaricata, Inga marginata and Esenbeckia grandiflora. In areas of waterlogged soil, the canopy is lower (20 m high) with more evergreen species, commonly including Rapanea sp., more Myrtaceae (e.g. Myrciaria baporeti, Myrcia bombycina, Eugenia uniflora) and palms (e.g. Geonoma schottiana, Syagrus romanzoffiana).
On extremely sandy or poor soil, species characteristic of cerrado vegetation (picture) are found in dense abundance. They are short (not over 5 m high); some show tortuous growth habits and some have corky bark. Diagnostic are Butia yatay, Allagoptera sp., Anadenanthera peregrina and Gochnatia polymorpha. Sometimes (in "campo sucio") only subshrubs and herbs are dominant.
Grasslands are dominated by graminoids such as Andropogon and Axonopus. In wetlands (marshes, lagoons), sedges (e.g. Eleocharis) and low herbs are dominant and the plants may form dense mats.
Located on a phytogeographic ecotone and possibly having served as a refuge for subtropical species during past climatic fluctuations, the reserve protects many regional endemics. At the generic level some of the endemics are monotypic: Hennecartia (Monimiaceae), Bastardiopsis (Malvaceae), Holocalyx (Leguminosae), Balfourodendron (Rutaceae) and Pseudananas (Bromeliaceae). There are many endemic species in genera that are widely distributed and highly specialized (e.g. Citronella gongonha, Arrabidaea mutabilis, Macfadyena mollis) as well as relictual (Diatenopteryx sorbifolia, Melicoccus lepidoctela, Patagonula americana).
The floristic affinities of the region with tropical areas to the north are clearly indicated by the presence of such tropical woody species as Annona amambayensis, Aspidosperma polyneuron, Cariniana estrellensis and Geonoma schottiana, and the predominance of major tropical families such as Myrtaceae, Bignoniaceae, Leguminosae, Moraceae and Meliaceae (Keel, Gentry and Spinzi 1993). Temperate affiliations can be seen among the diverse herbaceous taxa such as in Ranunculaceae, Scrophulariaceae, Polygonaceae and the predominantly woody genera Prunus and Hexachlamys.
This area is thought to have the highest floristic diversity in eastern Paraguay. Though the species diversity of the Mbaracayú region is relatively low presumably due to the subtropical climate and rather uniform topography, the regionally endemic species and especially genera, the mixture of tropical and temperate species, and as well the high density of lianas, make the forests of these wildlands significant for the conservation of plant diversity.
The Mbaracayú region contains rich timber resources and precious woods. Species marketed internationally include Tabebuia heptaphylla ("lapacho rosado, tajy"), T. impetiginosa, Cedrela fissilis ("cedro, ygary"), Balfourodendron riedelianum ("guatambu, yvyra ñeti"), Myrocarpus frondosus ("incienso, yvyra pajé") and Aspidosperma polyneuron ("peroba"). Balfourodendron makes up 9.3% of the commercial volume of timber in the region. These resources are in critical need of protection from excessive logging (Tortorelli 1966; López et al. 1987; Peace Corps Paraguay, undated; Zardini 1993).
Some forests also have extensive stands of Copaifera langsdorfii ("kupay"), whose resin can be transformed into diesel fuel (López et al. 1987). Other forests harbour wild populations of Ilex paraguariensis ("yerba mate" or Paraguayan tea), which is of considerable economic importance in the Southern Cone (FMB 1989). Fruit crops such as the pineapple (Ananas comosus) and custard apple (Annona spp.) have wild relatives (Pseudananas ananasoides and Annona amambayensis), providing other examples of the need for in situ conservation of the germplasm diversity in the Mbaracayú Reserve.
The indigenous Aché and Guaraní peoples make extensive use of the flora and have an abundant pharmacopoeia that merits further study for compounds with medicinal value. The powdered bark of Tabebuia impetiginosa ("pau d'arco", "taheebo" or "lapacho" tea), which is said to improve the immune system (e.g. Tierra 1988), is sold as a medicinal in the U.S.A. and Europe. A preliminary species list of the economic plants in the Mbaracayú region has been prepared (CDC-Paraguay 1991; Keel, Gentry and Spinzi 1993).
Social and environmental values
At present there are two ethnic groups settled near the Mbaracayú Reserve, the Aché and the Guaraní (FMB 1989). The traditionally nomadic Aché lived in the eastern forests as hunters and gatherers until 1975-1979. They are slowly adapting to the life of small farmers, although they still need the remnant forests' fauna and fruits for an adequate diet (Homer 1992). The Guaraní survive on subsistence farming.
They go to the reserve to collect yerba-mate leaves and less often to hunt. The Fundación Moisés Bertoni and The Nature Conservancy (TNC) have developed a land management programme for the indigenous peoples to continue their traditional uses of the Mbaracayú forests (FMB and TNC 1991).
These forests protect the Jejuí watershed (picture). The Mbaracayú Reserve is the source for various tributaries of the Jejuí-mí River, which later as the Jejuí-Gauzú River joins the Paraguay River. Designed to protect one of the few remaining subtropical moist forests in Eastern Paraguay, the Mbaracayú Reserve has an important role as well in securing diverse habitats for many species of the regional fauna, including threatened species and some of the prominent mammals and birds of Paraguay such as jaguar, ocelot, margay, bush dog, tapir, giant armadillo, king vulture, macaw, bare-throated bellbird, bare-faced curassow and burrito (CDC-Paraguay 1991).
The general region has important areas of evergreen humid forest ("Atlantic" forest) and remnant Araucaria forest which support a number of birds that have restricted ranges - including the canebrake groundcreeper (Clibanornis dendrocolaptes) and creamy-bellied gnatcatcher (Polioptila lactea), or that are threatened. The region is important for the following five threatened birds: black-fronted piping-guan (Pipile jacutinga), vinaceous amazon (Amazona vinacea), helmeted woodpecker (Dryocopus galeatus), So Paulo tyrannulet (Phylloscartes paulistus) and russet-winged spadebill (Platyrinchus leucoryphus).
In 1945 as much as 43% or 68,000 km² of Eastern Paraguay was still forested, but half that forest is now gone, as the land has been converted to other uses (Keel, Gentry and Spinzi 1993; Zardini 1993). The Jejuí Basin including the Mbaracayú area was used to obtain natural products such as animal hides, timber and particularly yerba mate until 1970 when the construction of roads began, which encouraged new settlements. Typically their purpose is to establish cattle ranches, or cultivate cash crops that often cause soil infertility (FMB and TNC 1991; FMB 1989). Deforestation, at a rate surpassing 1000-1500 km² yearly (Zardini 1993), in some places has reached the reserve boundary. Measures to prevent the reserve turning into an ecological island are urgently needed.
Except for the cordillera in the north-east near the border with Brazil, there are no effective natural barriers that protect the reserve, which also has several roads. Unless boundaries are well marked and an effective patrol system is put in place, theft of timber and fuelwood and poaching will continue to degrade the reserve.
In 1988, 0.13% of Eastern Paraguay was under the national protected area system. The Conservation Data Center (CDC) of Paraguay with support of The (U.S.) Nature Conservancy identified 23 potential areas for conservation in six ecoregions, with the Mbaracayú Wildlands figuring as a priority site (CDC-Paraguay 1990). Acting on the CDC-Paraguay recommendations, Paraguay's Ministerio de Agricultura y Ganadería (Ministry of Agriculture and Livestock) decreed five new National Parks, one new wildlife refuge and greatly expanded protected areas in Eastern Paraguay. As a result, lands in the national protected area system have increased to c. 1.2% (2000 km²) of Eastern Paraguay.
The Fundación Moisés Bertoni is developing a system of private reserves in Paraguay. In 1991 the Conservancy and Fundación agreed to purchase the Mbaracayú land (with funding from private sources and USAID) from the International Finance Corporation (for US$2 million). This World Bank subsidiary was acting under its new conservation policy, and controlled the land because a forestry company in 1979 defaulted on a loan (FMB and TNC 1991; Homer 1992). The property has been made a patrimony of the Fundación Mbaracayú, which holds title and is in charge of managing the reserve. The Mbaracayú Reserve has been recognized by the Paraguayan government, and has received national media attention and nearby community support.
As a priority site selected for the USAID-supported Parks in Peril Program, the Fundación Bertoni working with TNC has been able to begin implementing the management programme. The 1989-1990 inventory (CDC-Paraguay 1991) established the baseline information used for managing the reserve. Land easement or the full purchase of intact forested areas as buffer zones will add effectiveness to the system of protection. Detailed ecological studies in several forest remnants in the adjacent eastern Alto Paraná Department provide some insights into forest dynamics and life histories of many species in the Mbaracayú Reserve (Stutz de Ortega 1986, 1987). The reserve's future as a sanctuary in eastern Paraguay may be bright.
Map 54. Mbaracayú Reserve, Paraguay (CPD Site SA18)
CDC-Paraguay (1990). Areas prioritarias para la conservación en la Región Oriental del Paraguay. Centro de Datos para la Conservación (CDC), Asunción. 99 pp.
CDC-Paraguay (1991). Estudios biológicos en el área del Proyecto Mbaracayú, Canindeyú, República del Paraguay. CDC, Asunción. Unpublished report. 115 pp.
FMB (1989). Análisis socioeconómico y cultural de las poblaciones asentadas en el área de influencia del Proyecto Mbaracayú. Fundación Moisés Bertoni para la Conservación de la Naturaleza (FMB), Asunción. 51 + xlv pp.
FMB and TNC (1991). Mbaracayú Nature Reserve management program. A Park in Peril work plan. FMB, Asunción and The Nature Conservancy (TNC), Arlington, Virginia, U.S.A. Unpublished.
Homer, S. (1992). The last hunt: on the trail with Paraguay's forest people. Nature Conservancy (Nov.Dec.): 24-29.
IIED, STP and USAID; Raidán, G. (1985). Perfil ambiental del Paraguay. International Institute for Environment and Development (IIED), Secretaría Técnica de Planificación (STP) and U.S. Agency for International Development (USAID). Cromos, Asunción. 162 pp.
Keel, S., Gentry, A.H. and Spinzi, L. (1993). Using vegetation analysis to facilitate the selection of conservation sites in eastern Paraguay. Conservation Biology 7: 66-75.
López, J.A., Little Jr., E.L., Ritz, G.F., Rombold, J.S. and Hahn, W. (1987). Arboles comunes del Paraguay. Cuerpo de Paz, Washington, D.C. 425 pp.
Peace Corps Paraguay (n.d.). Forestry training manual. Paraguay.
Stutz de Ortega, L.C. (1986). Etudes floristiques de divers stades secondaires des formations forestières du Haut Parana (Paraguay oriental). Floraison, fructification et dispersion des espèces forestières. Candollea 41: 121-144.
Stutz de Ortega, L.C. (1987). Etudes floristiques de divers stades secondaires des formations forestières du Haut Parana (Paraguay oriental). Structure, composition floristique et régéneration naturelle: comparaison entre la forêt primaire et la forêt sélectivement exploitée. Candollea 42: 205-262.
Tierra, M. (1988). Planetary herbology. Lotus Press, Santa Fe, New Mexico, U.S.A. 485 pp.
TNC (1992). Evaluación ecológica rápida. Un manual para usuarios de América Latina y el Caribe. TNC, Arlington, Virginia, U.S.A.
Tortorelli, L.A. (1966). Formaciones forestales y maderas del Paraguay. Universidad de Asunción, Facultad de Agronomía y Veterinaria, Asunción.
Zardini, E.M. (1993). Paraguay's floristic inventory. Natl. Geogr. Res. Explor. 9(1): 128-131.
This Data Sheet was written by Dr Shirley
Keel (The Nature Conservancy, Latin America Science Program, 1815 North Lynn St.,
Arlington, VA 22209, U.S.A.) and Olga Herrera-MacBryde, Smithsonian Institution, SI/MAB
Program, S. Dillon Ripley Center, Suite 3123, Washington, DC 20560-0705, U.S.A.).
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