This particular eco-region, as defined by the convergence of the biogeographical provinces of Chaqueña del Espinal, Pampeana and Mountain, has been influenced by many types of flora and fauna. It is regarded as an "island" due to its specific biogeographical characteristics and it is thus distinguished from other areas within the environment of Chaco by its altitude and the species that inhabit it.
Flora Several phytogeographical provinces converge here: Chaqueña, Andean, Patagonian and Magellanic. The confluence of these very diverse currents confers on the area a synthesis of
microclimates which makes it unique, a uniqueness accentuated by the presence of
endemic species, the number of which is probably greater than is presently known. In the ravines and on the mountain slopes are copses or small woods of
tabaquillo (
Polylepis australis) and
mayten (
Maytenus boaria), called in the mountain zone "quebracho", the coexistence of which is a unique biogeographical phenomenon. The tabaquillo has relatives which are distributed the length of the
Andes from Venezuela to Argentina, while the mayten originates from the woodlands of south-west Argentina (the cool Andean-Patagonian woodland). The greatest density of these woods is in the bottoms of the ravines, where they acquire a low forest physiognomy with great quantities of
ferns and
epiphytes. Both the grasslands and the woodlands of the pampas and of the ravines respectively are composed of plants of very diverse origins. Some, approaching from the eastern slopes of the mountainous area, are native to the Austro-Brazilian region. Other species of specifically Andean origin have in the Pampa de Achala their most southerly distribution. On the other hand, numerous species of the south of Argentina find in this region their most northerly habitat. Not only the rocky walls of the ravines but also the granite outcrops of the Pampa de Achala, at first glance sites deprived of vegetation and of fauna, represent highly diverse habitats, capable of sustaining in their cracks and fissures a flora and fauna of significant scientific interest. Below the 1,500 metre line, the tough grasslands of the high altitudes are replaced by thickets in which the
romerillo (
Heterothalamus alienus) predominates. The high altitude woodlands make way for the mountainous Chaqueño woodlands, with trees of
molle and
coco. Five types of grassland plant communities have been identified in the plains;
Sorghastrum and
Stipa stony grassland,
Muhlenbergia short grassland,
Festuca medium height grassland,
Deyeuxia grassland and
Poa tall grassland. and
Bufo achalensis,) and the "Achalan frog" (
Odontophrynus achalensis). ;Birds Eleven subspecies and species of birds of the Passeriform order of Andean-Patagonian lineage are exclusive to this area, including:
rufous-banded miner,
common miner,
bar-winged cinclodes,
white-winged cinclodes,
cordilleran canastero, puna castanero,
white-tailed shrike-tyrant,
cinereous ground tyrant,
plain-colored seedeater,
plumbeous sierra finch (also known as
yal plomizo) and
ash-breasted sierra finch (also called
yal chico),
long-tailed meadowlark (
Sturnella loyca obscura), which nests in the ground and in large, oddly-shaped rocks. The most inaccessible cliff walls are used as nesting sites by the
black-chested buzzard-eagle (
Geranoetus melanoleucus), the
peregrine falcon (
Falco peregrinus) and the
Andean condor (
Vultur gryphus). The Andean condor is one of the more recognized species in the area; as of 2007, 101 Andean condors remained in the region. The
king vulture (
Sarcoramphus papa) has also been spotted in Pampa de Achala. ;Mammals Among the 30 other species of mammals native to the region is the culpeo or
Andean fox (
Lycalopex culpaeus),
puma (
Puma concolor), the
colocolo (
Leopardus colocolo); and
Geoffroy's cat (
Leoparudus geoffroyi). Small rodents and hare are also abundantly present in the area.
Guanacos have recently been reintroduced to the region, as they were disappearing slowly towards the early twentieth century. ;Insects The local
scorpion, (
Urophonius achalensis), is of particular interest. Of the numerous species of
arthropod, the
fire ant () stands out on account of the size of its nests and pathways. ;Reptiles '') Along the arroyos are well-watered areas (fertile plains, marshes) and reed beds where the native coral snake
Liophis anomalus () feeds on the local tree frog
Hyla pulchella ( or "bramble-patch frogs"). An endemic species is also to be found, the eye-catching green lizard of Achala,
Prystidactilus achalensis. The sole venomous snake is a species of
hognose snake,
Lystrophis dorbignyi (). ;Fish The commonest species of fish in the water courses of the Pampa de Achala are the
rainbow trout, arroyo trout (
Salvelinus fontinalis),
Astyanax fasciatus (), and . Indiscriminate fishing has caused the loss of numerous species throughout the region (and indeed the entire province). The rivers and
arroyos are perpetually being re-stocked with salmon, with the intention of maintaining the ecology. Regrettably the goal can never be reached, as secret fishing is constant and difficult to control, and has caused the loss of very many species. As at September 2009, all fishing in all locations throughout the province is forbidden during the hours of darkness. ==History==