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The Iquitos region of western Amazonia is mainly in Peru's Department of Loreto, including portions of the provinces Maynas, Loreto, Ramón Castilla and Requena and the eastern buffer zone of Pacaya-Samiria National Reserve. For conservation purposes, the southernmost extension of Colombia is considered part of the Iquitos region. Colombia is to the north of the region, Brazil to the south, and both countries are to the east (Map 45).
The major urban centre is the port city of Iquitos, which is located in the north-western part of the region on the west bank of the Upper Amazon River at 106 m in elevation. Iquitos is 600 km east of the base of the Andes and 3636 km west of the Atlantic Ocean (ONERN 1975). The Putumayo River marks the general area's northern boundary with Colombia and the Yavari/Javari River its southern boundary with Brazil. The principal rivers traversing the region are the Napo, Marañón and Ucayali, which become the Upper Amazon (to Solimões) River (Peñaherrera 1989).
The Iquitos region formerly constituted an east-west geosyncline, which in the Cambrian period formed a basin of water that connected to the Pacific Ocean. During the Miocene with the initial rise of the Central Andean Cordillera, drainage was redirected to the Atlantic Ocean, creating a giant lake which slowly filled with assorted sediments (Encarnación 1985). Thus formed the extensive lowland plane of degraded Tertiary and Quaternary alluvial deposits that cover much of the Central Amazon sedimentary basin.
As a result of these geological phenomena, there is very little altitudinal differentiation. The older deposits constitute the non-flooded "tierra firme" - terrain found in most of Amazonia, which has few if any essentially permanent lakes (Räsänen, Salo and Jungner 1991). Soils of more recent origin are restricted to active floodplains or várzeas (Meggers 1971). "Várzea" is continually enriched by new deposits of Andean sediments, and has successional riverine features including a complex system of many lakes.
Due to different substrates, there is a complex habitat mosaic. Characteristic substrates include upland white sand; upland lateritic soil; non-inundated alluvial soil; and "tahuampa" - floodplains seasonally inundated by either suspension-rich white water or suspension-poor black water. This mosaic of habitats is more completely developed in the black-water river area of northern Loreto Department; it reaches its southern limit near Jenaro Herrera on the Ucayali River and extends eastward to Leticia (Map 45) (Gentry and Ortiz-S. 1993).
The climate of the region is relatively uniform (Encarnación 1985). The average annual temperatures are between 25°-27°C, with diel variations of less than 8°-10°C, and a minimum of 16°C occurring during June and July. Annual precipitation ranges from 2386 mm at Leticia to 2400-3400 mm. The Iquitos region has no well-marked dry season. The complete absence of seasonality of the rainfall in diverse warm habitats probably is a key factor responsible for considering this region and the Western Amazon in general as the world's highest in diversity of tree species and several other major groups of organisms (cf. Gentry 1988b; Gentry and Ortiz-S. 1993).
The distinguishing phytogeographic characteristic of the Amazon is its magnificent tropical rain forest, which A. von Humboldt called the hylaea. Detailed classification of the vegetation of the Peruvian Amazon is very incomplete. In the Holdridge life-zone system, it is considered primarily tropical moist forest ("bosque húmedo tropical"), and many subcategories have been recognized (ONERN 1976). Studies of the Iquitos region have resulted in various classifications (Tuomisto 1993). The major types found are upland forests and wetland forests, each of which also correlates with more shrubby vegetation (Encarnación 1985).
The Peruvian Amazonian region is unique as a tectonically active foreland occupied by often pristine tropical rain forest (Kalliola et al. 1991). The vegetation is highly dynamic, which implies that a large proportion of the forest is transitional. Even relatively stable sites can become destablized through abrupt changes in habitat conditions. Succession associated with this geologic dynamism plays an important role in the patterns of the Iquitos region, which has a very complex and intricate mosaic of habitats. Although the climax vegetation is generally tropical moist forest, on different substrates there are floristically different communities. While the species composition of the communities on the different substrates is very distinct, the familial composition of different communities is remarkably similar (Gentry 1988a).
Upland (tierra-firme) forests (Ruokolainen and Tuomisto 1993)
1. Vegetation on white-sand soils has two main formations:
2. Vegetation on lateritic soils is heterogeneous, and also less well known, although the most prevalent in the region. Edaphic conditions and variations in drainage appear influential. According to various studies (Gentry 1988a, 1988b), the lateritic soils have the highest diversity of plant species. Near Iquitos (4°S), while the white sand of a 1-ha sample at Mishana (near the Nanay River) had 83 trees 30 cm or more in dbh, the relatively richer lateritic soil at nearby Yanamono supported 110 such large trees (Gentry 1988b).
Wetland forests and woodlands, swamps and marshes
1. Seasonally or sporadically inundated vegetation is of three main types and several other successional types:
a) Flooded by regular annual cycles of rivers:
b) Flooded irregularly by overflow of rivers or local torrential rains:
2. Permanently inundated vegetation (swamps and marshes) is of three general kinds (Kalliola et al. 1991):
Preliminary data from several well-censused areas near Iquitos record 2265 species in ten sites, with 65% of the species known from only one of the sites (Gentry and Ortiz-S. 1993; Vásquez and Pipoly, in prep.). To the east in Colombia, c. 1500 species have been recorded in Amacayacu Natural National Park (Rudas and Pipoly, in prep.); sometimes these are the same species as those found near Iquitos.
An outstanding aspect of Iquitos forests is their high [alpha] diversity (Gentry 1988a, 1988b). Two 1-ha plots on different soil types in the Iquitos region were determined to be very rich in species of trees: at Yanamono (on alluvial-terrace lateritic soil) there were 580 trees 10 cm or more in dbh representing 283 species - only 15% of the tree (and 17 liana) species were represented by more than two individuals; Mishana (on white sand) had 842 such trees of 275 species. Thus the Upper Amazon rain forest may be the world's richest in tree-species diversity (Gentry 1986, 1988b). The Iquitos region's forests are also among the richest known in all plant species 2.5 cm or more in dbh, with 0.1-ha samples averaging 218 species (Gentry and Ortiz-S. 1993).
Usually Leguminosae is the most diverse family in Iquitos forests, although in some of the richest-soil areas Moraceae may present almost as many species (Gentry 1988b). Other prevalent woody families are Lauraceae, Annonaceae, Rubiaceae, Myristicaceae, Sapotaceae and Meliaceae. Palms are well represented in most Iquitos forests and are especially prevalent on richer soils (Vásquez and Gentry 1989). The most important liana family is Bignoniaceae (as in most of the neotropics), and then Leguminosae, Hippocrateaceae, Menispermaceae, Sapindaceae and Malpighiaceae (Gentry 1991).
Locally endemic species include Meliosma vasquezii (Sabiaceae) (picture), Caraipa utilis (Clusiaceae) and Aptandra caudata (Olacaceae). Some endemics in this region known only on sandy soil are Hirtella revillae (Chrysobalanaceae), Jacqueshubera loretensis (Leguminosae), Spathelia terminalioides (Rutaceae) and Ambelania occidentalis (Apocynaceae). Schlegelia cauliflora (Bignoniaceae) (picture) was considered a local white-sand endemic until recently, when it was found at Araracuara in Colombia (in CPD Site SA7).
The usefulness of the Iquitos forests to the people who live in them is varied and vast for food, remedies, construction, crafts, commerce, etc. Pinedo-Vásquez et al. (1990) studied 7.5 ha of the secondary communal forest adjacent to San Rafael (near Iquitos), finding that 60% of the 218 tree species (dbh 10 cm or more) and 66% (2511) of the individual trees were utilized for one or more purposes: for example, 28% of the species produce food; 10% remedies; 31% construction materials (including bark of Duguetia lucida and Helicteres pentandra for lashing to make houses); 5% crafts; and for commercial products - 24% timbers (only 26% of these trees were of the required 26 cm minimum dbh), 22% non-timber products and 7.6% exudates.
The forests around Iquitos include numerous edible species. Vásquez and Gentry (1989) recorded the uses of c. 220 fruits consumed by the local inhabitants, and determined that of 193 fruit species consumed regularly, 120 were exclusively wild-harvested. The taxonomic diversity of the fruits is outstanding: 39 families were represented and in 34 were species with wild-harvested fruits.
The family Palmae is preeminent, with 23 species producing wild-harvested fruits (Vásquez and Gentry 1989). The fruit of the palm Mauritia flexuosa is the most important. It provides a number of saleable products (Padoch 1988; Mejía 1992), including the raw ripe fruit ("aguaje"); "masa", a seedless mashed pulp; "curichi", a frozen drink; "chupetes" or popsicles and ice cream. Another important palm is Jessenia bataua, which produces an oil very similar to olive oil. The protein quality of its fruits is comparable to animal protein (Balick and Gershoff 1981); these fruits also are made into ice cream and sold in Iquitos (Kahn 1988). Young leaves of Euterpe precatoria (known as "palmito") are used to make salads, and its roots are used to treat some hepatic and renal problems (Mejía 1992).
Other notable fruit species found in the Iquitos region are Myrciaria dubia ("camu-camu") (Myrtaceae), which is exceptionally rich in vitamin C; and Grias peruviana ("sacha mangua") (Lecythidaceae), whose mesocarp is rich in vitamin A. Additional notable fruit-producing families in the region include Apocynaceae, Annonaceae, Moraceae and Sapotaceae.
Native traditions have been well preserved among the region's peoples, who generally continue to use many forest plants as medicinals. For example, Martinella is widely used as an eye medicine (Gentry and Cook 1984). A tea made from the leaves of Spondias mombin is used to treat diarrhoea, stomach ache, vaginal infections and dermatitis; a tonic made from its bark is claimed to be an effective contraceptive (Peters and Hammond 1990). Some medicinal plants are exported. For instance, much of the world's curare, which is used as a muscle relaxant in modern medicine, comes from the Peruvian Amazon. Also, there has been recent large-scale export of Uncaria bark from Amazonian Peru to treat prostate cancer (Gentry 1993). Other examples of species used medicinally are Abuta grandifolia - stems and/or roots to treat sterile women, post-menstrual haemorrhages and rheumatism; Abuta solimoesensis, bark to treat anaemia and rheumatism; Alchornea castaneifolia, bark to treat rheumatism, arthritis, muscle pain and colds; Ficus insipida var. insipida, latex as a vermifuge; and Ficus trigona, as an antidiarrhoetic (Duke and Vásquez 1994).
The Iquitos region has important timber species including Caryocar, Hymenaea, Iryanthera, Virola, Endlichera, Eschweilera, Aniba, Ocotea and Swartzia. Approximately 70% of the wood used to build houses in Iquitos is from Caraipa utilis (Vásquez 1991) and in Jenaro Herrera, from Haploclathra cordata (Vásquez 1993). Both of these species are endemic to the Iquitos region. Other species frequently used for construction include Aspidosperma nitidum (Apocynaceae); Caraipa densifolia, C. tereticaulis (Clusiaceae); Duroia paraensis (Rubiaceae); and Eschweilera turbinata (Lecythidaceae) (Soto and Vásquez 1989; cf. Pinedo-Vásquez, Zarin and Jipp 1992).
The climbing palm Desmoncus has been used locally as a fibre source for rattan products (Gentry 1986). Also, there is a thriving fibre industry based on the aerial roots of Philodendron solimoesensis (Araceae). Stems of various other monocotyledons including Ischnosiphon (Marantaceae) and Heteropsis (Araceae) are similarly used locally (Gentry 1992).
Social and environmental values
The Tamshiyacu-Tahuayo Communal Reserve, as well as similar areas not officially designated as reserves (Pinedo-Vásquez, Zarin and Jipp 1992), are a source of products from the fauna and flora for many rural inhabitants. The Iquitos region forests can offer important refuge for wild animals threatened by over-hunting. This is especially true in the areas north of the Napo; near the Brazilian border the hunting pressure has not been as severe.
The Iquitos region is embraced by the large Napo and Upper Amazon lowlands Endemic Bird Area (EBA B19), which extends from southernmost Colombia and eastern Ecuador eastward into northern Peru and westernmost Brazil. Ten species of birds are limited to this area, although they essentially represent the most restricted species of a (distributionally poorly known) suite of birds that are confined to the river islands, riverine forest and várzea forest of the Amazon Basin rivers. The birds in this EBA, just one of which is considered threatened, are seemingly confined to the tierra-firme or várzea forests.
The city of Iquitos has a population of over 269,000, and is the capital of the Department of Loreto (now Amazonas region), which has a low population density - 1.4 inhabitants per km². Most residents of the many riverine villages of the region are largely agriculturalists and generalists who may also fish, collect forest products, hunt, create or prepare some products (e.g. handicrafts, alcoholic drinks, medicinals) and engage in some wage labour (Padoch 1992). Certain native fruit species are beginning to be grown as crops, including Grias neuberthii, Inga minutula, Muntingia calabura, Passiflora quadrangularis, Pourouma cecropiifolia and Psidium guajava (Vásquez and Gentry 1989).
Wild-harvested fruits are important products in Amazonian Peru. Including those consumed occasionally, 219 wild-harvested fruit species are presently used by the people of the Iquitos region (Vásquez and Gentry 1989 and unpublished). The annual value per ha of a population of Myrciaria dubia in flooded forest is estimated to be US$5700-7620; the value of the fruit produced by Grias peruviana is US$4242, whereas Spondias mombin produces US$378 worth of fruit (Peters, Gentry and Mendelsohn 1989).
Of the 32 tree species at San Rafael with non-monetary use-values of 2.0 or more (based on addition of major and minor categorical uses), 78% have markets in Iquitos. Over-exploitation can result: Brosimum paraense and Heisteria pallida, with use-values of 3.0 and dependable markets, have been so depleted that only two trees of each were found in the sampled 10% of the 50-year-old secondary forests. In 1984 the community of San Rafael established a communal forest reserve (8 km²), which has detailed community rules for sustainable use (Pinedo-Vásquez et al. 1990; Pinedo-Vásquez, Zarin and Jipp 1992).
Funds raised by small-scale ecological tourism were used to build Quebrada Sucusari, a research laboratory on the Napo River with 1012 km². It is operated by the Amazon Center for Environmental Education and Research (through the ACEER Foundation).
Habitat destruction by deforestation, especially along navigable rivers, is due to population pressure (Aramburú 1984). Some species are deleteriously exploited for their products; e.g. the palms Mauritia flexuosa and Euterpe precatoria are cut down (Padoch 1988; Pinedo-Vásquez, Zarin and Jipp 1992). Over-hunting for food (e.g. deer, peccary) and trade (e.g. live birds and primates) has reduced populations of important agents for dispersal in much of the region.
The Tamshiyacu-Tahuayo Communal Reserve (3225 km²) is located in north-eastern Peru between the rivers Tamshiyacu, Tahuayo and Yavari Miri (or Mirim) (Map 45), approximately between 4°11'-4°56'S and 72°30'-73°17'W. It is predominantly non-flooded forest (tierra firme), and has 13 primate species; for two (Saguinus mystax mystax and Cacajao calvus rubicundus), this is the first protected area.
This reserve is managed in ways to benefit the local people; there are management programmes for the aguaje palm, ungulates, fisheries and swidden-fallow agroforestry (Bodmer et al. 1990). At least 44 village and inter-village forest and/or lake reserves which total 128 km² have been established by local communities to prevent misuse and develop sustainable extraction of their natural resources. Their efforts are aided by the grassroots organization FEDECANAL (Federación Departamental de Campesinos y Nativos de Loreto) (Pinedo-Vásquez, Zarin and Jipp 1992).
The Iquitos region includes only the eastern buffer zone of the Pacaya-Samiria National Reserve, which is an important preserve for wetland forests and the region's aquatic fauna, and the only officially designated large reserve in northern Amazonian Peru. Several national and international conservation organizations are conducting intensive research in the area in order to develop strategies to protect this reserve.
North of the Amazon River on the border in Colombia (Leticia municipality) is Amacayacu Natural National Park (1700 km²), between 3°02'-3°50'S and 69°54'-70°20'W (INDERENA 1990). Peru may extend the protection to form a large binational park, which could become one of the most important conservation units in Amazonia.
Map 45. Iquitos Region, Peru and Colombia (CPD Site SA9)
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Vásquez, R. (1993). Una nueva Haploclathra (Clusiaceae) de la Amazonia peruana. Novon 3: 499-501.
Vásquez, R. and Gentry, A.H. (1989). Use and misuse of forest-harvested fruits in the Iquitos area. Conserv. Biol. 3: 350-361.
Vásquez, R. and Gentry, A.H. (in prep.). Catálogo de los frutos comestibles de la Amazonia peruana. Universidad Nacional de la Amazonia Peruana, Iquitos, Peru and Missouri Botanical Garden, St. Louis, U.S.A.
Vásquez, R. and Pipoly, J. (in prep.). Flórula de las reservas biológicas de Iquitos. Universidad Nacional de la Amazonia Peruana, Iquitos, Peru and Missouri Botanical Garden, St. Louis, U.S.A.
This Data Sheet was written by Rosa
Ortiz-S. (Missouri Botanical Garden, P.O. Box 299, Saint Louis, MO 63166-0299, U.S.A.).
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