Vegetation and flora- The composition of the Bolivian flora is affected both by the central position that the country has on the South American continent, and by the fact that its political border excludes the entire western side of the Cordillera. It therefore completely lacks the element typical of the Pacific side but instead presents a very notable development of the Andean element and of the Amazonian and Argentine oriental elements, so as to become one of the richest tropical flora of the South American continent. Ecologically the course from NO. to SE. of the Eastern Cordillera, forming almost the backbone of the region, identifies two sectors, one in the north-eastern humid and essentially Amazonian, the other in the south-western dry and actually reaching the dryness of the desert on the plateau, of Andean-Argentine character The upper limit of the forests fluctuates on the northern slope of the Cordillera where rainfall approaches 3000 mm. per year, between altitudes between 3200 and 3400 meters above sea level, but proceeding towards the SE. it lowers up to about 1700 m. For Bolivia 2013, please check physicscat.com.
In any case and with reference to the general classification of the formations of the Andean region (see ande), the vegetal landscape of the two districts distinct above is approximately the following: in the north-eastern region and precisely in correspondence with the river network constituting the upper course of the Madeira (Beni, Mamoré, Madre de Dios) the Amazonian rainforest (hylaea) continues on the northern side of the Cordillera with the tropical montane forest distributed in the characteristic altitude zones. We have that, starting from the base and up to 1500 m. on the sea, the upper humid and still preserving tropical character of the palms and tree ferns; then, between 1500 and 2400 meters above sea level, the Cinchona area (yungas), with strong permanent humidity, but significantly lowered thermal average and reflecting on the composition of the flora, of which however a palm (Oreodoxa frigida) belongs, Orchids and epiphytic Bromeliads, abundant lianas, Scitaminee (Amomum), Guttifere (Clusia), numerous Melastomaceae, etc.; then a third zone – ceja de montana – zone of fogs covered by a dense and low forest of arboreal and shrub sclerophyllous, heather and bamboo with branches covered by a dense mass of moss. Towards the south of the interior, the equatorial forest passes into the well-known Brazilian caatinga formation, a forest of low trees with deciduous leaves and generally xerophilic posture, interspersed with areas with thinned out or missing tree vegetation with the appearance of savannah or steppe (campos, carrascos). On the other hand, the vegetation in the south-western area is more varied, including first of all, in southern Bolivia, a large stretch of plateaus with the characteristic desert steppe landscape of the Puna, steppe vegetation dominated by Stipa ichu, a grass with rigid tufts arranged in circles and encrusted with sand on the dominant wind side, by extensive areas covered by a Composita – Baccharis tola – as well as by species of Cactee (Echinocactus), Umbelliferae, Verbenaceae, Genzianaceae, Valerianaceae, etc. Around Lake Titicaca it is worth noting the existence of an area of lean crops to which some tree species also come from the surrounding areas; while in the salient points of the plateau the last islands to the north of the Antarctic vegetation persist (Azorella). Towards the interior, then, on the eastern slope of the Andes is occupied by a preservative Argentine forest still in its lower area a distinctly subtropical, with legumes (Machaerium), Lauraceae (Nectandra), Iuglandee (Juglans), Meliacee (Cedrela); while the upper one already presents a temperate landscape dominated by Conifers (Podocarpus angustifolia) and some particular broad-leaved trees (Alnus aliso, Sambucus peruviana). Along the foot of the Cordillera still belong to Bolivia of the first traits of the formations in the park of the Gran Chaco, grasslands alternating with arbustacee spots of a Bougainvillea (Duragnel, Bolivia Praecox), bushes of a palm tree (Copernicia), etc.
Fauna. – The fauna of Bolivia has this peculiarity: that from the purely Chileno-Patagonian character that it presents in the west and southwest, it passes almost without transitions to the Brazilian character in its northern and north-eastern part. The Andes constitute a clear barrier of separation for many species and for many families of animals.
Western and southern elements are the spectacled bear (Tremarctos ornatus), the Chinchilla and lagidium, llamas (Lama vicugna and L. Guanacus); among the birds: the Phytotomidae, the Pteroptochidae, the Anatidae Chenonettinae and Merganettinae, the Thinocorythidae, the Rheidae. The Brazilian character is given by the presence of cebi, Cailitrichidae, Procyonidae, jaguars, hares, aguti, guinea pigs, including the Cavia boliviensis and the big Hydrochoerus capibara, porcupines (Erethizontidae), peccaries (Dycotyles), anteaters, numerous families of birds and reptiles and apodic amphibians.
