The ecology of Perú

The ecology of Perú

It would be worth reading the section on the geography of Perú before reading this one, as the extremes of the country define the ecosystems which it supports. There are three major land divisions which between them support five major biogeographical regions in Perú. In plain languages, there are five countries rolled into one.

The five regions are:

Yunga 500-2300m cactus, fruits, vegetables, maize
Quechua 2300-3500m maize, potato, gourds
Suni 3500-4000m quinua, cañihua, tarhui, beans
Puna 4000 - 4800m pasture, some potatoes
Janca 4800 upwards pasture or barren
These designations are also used in describing village lands, in ways which are confusingly just different from the "geographical" usage. Only puna is widely used outside village life, and cordillera is normally used in place of janca

A more detailed assessment shows how extraordinarily diverse Perú actually is. International convention divides the world into various types of ecosystem. There are, altogether, just over a hundred of these that are recognised by science. With only minor straining, no less than 84 of these can be found in Perú!

Recent studies of the World's biodiversity hot-spots place at least five of these in Perú. In particular, the Tambopata and Manu regions possess two of the most diverse flora and fauna forests in the world.The Pongo de Manique Canyon on the Urubamba River is alleged to be the most biodiverse area on Earth's surface. It is, however, a relatively accessible area and so has been studied with more intensity than the backwoods. There may well be more diverse regions elsewhere. Perú is the source for many of the commercial Solanaceae, such as potatoes and tomatoes. The author was involved in the sponsorship of a university study of tomato diversity in the Marañon valley. The team had planned to cover the entire headwater region, but in fact ran out of time after traveling only a few kilometres of their planned route, such was the local diversity.

Perú has the fourth largest expanse of primary forest in the world. Tropical forests are almost always extremely species-rich. The Perúvian jungle is no exception, with up to two hundred different kinds of large tree cramming themselves into a hectare of forest.

Insect life is poorly assessed, but the Tingo María region is famous for its butterflies, and it is frequently necessary to scrub the radiator of a car to remove the accumulated insect debris when driving through the region on damp, evening mud roads. Perú and Ecuador are the heartland of a range of mist-forest orchid genera. The ceja de selva is particularly rich in these plants in areas where rock breaks forest into a myriad of patches. However, the are epiphytic orchids growing to 3800m, probably a world record. At least two species of cactus grow under snow cover at 4500m. There is an extraordinary diversity of medicinal plants, all readily available from market stalls. At least five narcotic plants grow in Perú - the coca shrub, the three plants used in the ayahuasca brew, the hallucinogen cactus known as el cactus de San Pedro - and probably many more.

In common with most mountain biomes, the Andes offer a very wide range of niches, in which species and varietal differences proliferate. The parrots or butterflies in one valley are often quite not the same as those over the ridge. This, too, has been little studied, in part due to the narcotics-related security problem of this part of the country. However, private orchid collections in Moyobamba (el pueblo de las orchideas) show a very wide range of regional variation within a given species. A given Lycaste, for example, may vary in size by a factor of four, support very different flower coloration and distinct growth patterns. Butterfly collectors report similar variation.

The coast

The coastal desert strip is 2530 km long and never more than 80km wide. It is usually much more narrow, and ocean influences often reach the mountains very directly. Fifty three valleys are subject to cultivation, chiefly of sugar and cotton but also - near towns - of vegetables and a more diverse range of crops. Tamarind trees are commonly planted for shade, and the ecology is largely created by man.

This is, however, far from the end of the story. The Humboldt current has already been mentioned. Its affects are two-fold. In the ocean, it brings an upwelling of nutrients which support a vast and complex web of life. Humans have fished the current extensively, reducing the flow of food to the top predators, and the enormous numbers of sea lions (lobos del mar) and other mammals is lessened. The sea birds, whose droppings contributed so much to the wealth of Perú in the Nineteenth century through the guano trade are also diminished. Nevertheless, both are still plentiful and are best seen in the Paracas sanctuary, near Ica in the South of the coastal strip. The number and size of the jelly fish that one can see are remarkable - pale mauve things the size of a dining table, with tendrils like hose pipes. Pelicans bomb the sea around you as you sit in a boat.

There is little or no rainfall on the coast. However, in common with Namibia, there is significant condensation from cold coastal fogs, and a whole ecology thrives on this. This evidences itself in, for example, vast swarms of insects which suddenly descend on the cotton crop, seemingly from nowhere. However, the ridges or lomas that rise up to the Andes in fact support a remarkable range of life. There are about 2000 square kilometres of this vegetation, dispersed in some 145 thousand square kilometres of desert. These patches taper off at around 1000m into dusty cactus-dominated scrub land, itself supported by meager seasonal rains. (This strip comes to the coast near Tumbes, on the Ecuador border, and is subject to National Park status as los Cerros de Amotape.) This 2000 square kilometre region offers five distinct ecological zones. There are over 500 species of higher plant in the region, many of which are endemic and therefore unique.

The vegetation of the lomas consists of ephemeral herbs, mixed with woody scrub. Immersed in their mist, these dusty, dank elfin forests have an alien look that will, no doubt, one day be exploited in a science fiction movie. It is estimated that around 600 plant species exist on the lomas, and many are highly endemic and, therefore, probably threatened by potential human disturbance. There is a shifting insect population of at least a hundred species, and dozens of vertebrates such as lizards, birds and small mammals.

The Andes

The long strip of the Andes make up about a quarter of the "map" area of the country, but in fact offer much more surface due to their often steep inclination. As already mentioned, there are sharply different biomes. A transect across the Andes is shown in the figure.

Farming has an extensive history in the Andes, with most valleys being settled. Land use is complex, with various crops and activities being allocated to different altitudes and types of exposure. The "suni" lies over 3500m and is used largely for grazing. The upper arable lands of the village are called the "quechua" (giving its name to the second official language of Perú.) These are used chiefly for potatoes and quinua, a crop plant that was, until recently, unique to Perú. It is now being tried in Nepal, which is now also dependent on potatoes and maize derived from Perú. Lower land, closer to the river and valley bottom, is called the "yunga" and is used for the more tender crops such as maize, fruit and vegetables.

A few of the potato varieties growing in a single village

The yungas occupy around 186,700 square kilometers. Rainfall varies enormously, from arid semi-desert areas to wet forest, receiving half a metre a year of rain, extended by condensation and constant high humidity. These last have dense evergreen vegetation, which may exist as large undisturbed blocks, or as dissected parcels following the topography. Species diversity is high, with many species being endemic. Some are very strange: at 35 cm tall and 5kg, the pudu is the smallest deer in the Americas. It lives only in the Eastern forests in the high Andes.

The omnipresent Ichu grass of the alitplano

These forests host a wide range of butterflies, birds (yellow-browed toucanets are common, for example) and other animals. Bats are common all over the Andes, but the yungas have many endemic species. There are many orchids. As yet, these habitats are largely untouched at higher altitude.

Elsewhere in the Andes, the impact of human activity over the centuries has been extensive, and almost all of the Western Andes and altiplano have been formed by human actions. There is, nevertheless, extensive wild life to be found. The altiplano covers nearly quarter of a million square kilometres, and supports over a thousand higher plant species, many of them endemic. Its wetlands are particularly rich in bird life. Odd patches of dwarf forest are also home to unusual birds. The king of the air is, however, the condor (Vultur gryphus) which, despite its massive size and good public relations is nevertheless a carrion-eating vulture. The rivers are home to birds and aquatic organisms that specialise in fast-running torrents, and the antics of the birds, in particular, are remarkable as they plunge into large waterfalls in search of prey.

The Andes become wetter as one travels North. The Southern coastal foothills and altiplano are extremely arid. However, by the Ecuador border, matters have changed. The coast is still largely desert, but the Western flanks of the Andes are now much wetter. The 30,000 square kilometre region around Huancabamba is thought to be particularly biodiverse. It rises from about 1000m to 4000m, and offers dry and cactus forest at lower elevations, moving to montane cloud forest and eventually to the heath land of the puna. There are known to be at least 2500 vascular plant species that grow here, many of them unique to the region. There are also many endemic animals, including birds.

This said, the Eastern slopes of the Andes are always wetter and usually much more interesting to the wild life enthusiast that those on the West. These regions are, of course, also the chief source area for cocaine, so visitors should be aware of the precautions which they need to take. Each valley is cut by a separate river, and most are far more precipitate than their equivalents on the West. Very steep cliff faces are threaded by roads and footpaths, and draped with greenery. The orchid flora is remarkable and unique. The whole biome covers around quarter of a million square kilometres, and it is safe to say that most of its biology has not been much explored. There are at least 7000 and probably in excess of 10,000 plant species in the region. It is home to humming birds and parrots, bears and large carnivores. The region is essentially indescribable to those who have not been there: imagine all your ideas of tropical jungles and mountains rolled together and you will get some idea of the richness that exists. Standing by his car, the author counted well over forty orchid species in the time it took him to urinate. Three different kinds of parrot flew past, and a toucan.

The jungle

The jungle makes up nearly two thirds of Perú's land surface. It is sparsely inhabited and, in terms of science and ecology, it is little known. However, the patches which have been studied are amongst the most diverse places on Earth.

The alta selva, the high jungle, is much disturbed. Coffee is grown, as well as tropical crops such as sweet potatoes, cassava and fruit. Indigenous peoples call the land above 400m the rupa rupa, and the lower alta selva the omagua. It is an extremely wet area, with some locations attracting five metres of rain annually.

The lower selva rain forest is quite various, with areas that are nutrient deficient, areas subject to seasonal flooding and differences based on the soil type. There are, therefore, regions of open savannah and closed forest, patchy scrub and swamp. Almost all of this is inaccessible except by aircraft or boat, and entrance into the forest is largely constrained by logistics to the edges of it. Travel in the region is monotonous and it is far better to establish a base and let this world come to you. The river offers fresh water dolphins (and many rather dangerous animals - see the section on emergencies.) The dolphins are said to father children on the local women, both a convenient excuse and a recognition of the displays put on by male dolphins when menstruating women swim. (The dolphins are also said to manifest themselves as urbane and seductive men, wearing a special hat which they do not remove during intercourse. The hat covers their blow-hole!)

Bird life is striking, but one needs to get one's eye in before one can see much from within the canopy. Rivers - and in particular, bare river banks seen from a boat, offer by far the best perspective. The parrots of Madre de Dios visit riverbanks to eat clay, supposedly to absorb toxins in the seeds which they eat. One can see multi-coloured walls of these birds from a boat. Clay-eating is a common habit in the jungle, and wallows attract many species of animal and insect. Whether the motivation is indeed to neutralize toxins or to replenish scarce minerals, the result is an extremely attractive way by which to view the less visible life of the selva.

The entire district of Loreto is now regarded as being of international importance by virtue of its pristine biodiversity. The complex of wetlands (Abanico del Río Pastaza) has been recognised as being of particular value. Other large parks have been established, but happily human pressure is currently limited to the fringes of the jungle.

The area around Iquitos is better known that most of the selva. It consists of varied evergreen tropical forests and shrubby woodlands, swamps and marshes. There is, therefore, a complex mosaic of habitats which support what is possibly world's highest diversity of tree species. Many plants are endemic - that is, they are not found anywhere else. The Manu park in upper Amazonas is also a patchwork of swamp and tropical rain forest, and it offers a known 2000 plant species, many of which are either endemic or restricted to south-western Amazonia. It is home to the giant boa constrictor as well as to hundreds or thousands - for who knows? - of less iconic animal species.

Plants are relatively easy to name, to preserve and to define. They stand still, and they are there during the day. Animals and insects are less easy to capture, yet a single tree yielded over 2000 insect species when it was fumigated. Many are yet to be named. Fungi, bacteria and soil insects are barely studied, yet they make up the numerical majority of the species and the greater part of the biomass of the region. When you tread in the selva floor, you tread on the unknown.

Safe and revealing visits to the selva are fairly easily achieved with proper planning. There are dangers, but these are containable. Please do read the section on malaria and other insect-born diseases, however, if you do plan a visit. The chief danger is that of getting lost, which it is easy to do in a featureless forest. It is absolutely essential to take a guide who is thoroughly familiar with the forest and who has been raised within it.