Climate and vegetation

Huarango forestThe project is based in the Ica region on the south coast of Peru, where over 700,000 people make their homes. The south coast is part of the Peruvian Chilean desert (including the Sechura and Atacama) that runs for over 3,500 km alongside the Pacific Ocean. This strip of western South America is one of the world‘s oldest and driest deserts. The climate is ‘hyperarid’ with an average rainfall of less than 3 mm per year.

The desert is flanked to the east by the vast Andean mountain range. Unpredictably, from November to April as moisture from the Amazon spills over the Andes, the coastal rivers flow and aquifers are recharged, bringing life to the desert. From around June to December plants can survive by capturing seasonal fog from the sea. Also, every 10 to 15 years El Niño flooding provides the pulse needed to sustain and regenerate vegetation. On the coastal plain of Ica temperatures range from a minimum of 8˚C in June to a maximum around 35˚C in March, although occasionally peaking at over 40˚C.

Although highly deforested, about ten types of natural vegetation and habitat are still found providing for biodiversity. These include: Lomas fog vegetation, riparian dry forests, cactus-rich scrub, Prosopis dunes, seasonal streams, oases and saltmarsh. Also of great value to people and biodiversity is the irrigated vegetation found in Huertas (forested kitchen gardens).

The south coast is under considerable population pressure and competition for water. Overgrazing and land conversion have meant the inevitable loss of forest as well as saltmarsh, riparian and xerophytic ecosystems and degradation of coastal lomas with its endemic flora. The remaining dry forest on the Peruvian south coast has undergone centuries of deforestation and is today near extinction as a natural ecosystem. However, the forest provides a valuable if not essential resource for people and biodiversity. The dominant tree is the Huarango - a leguminous hardwood that has played a fundamental role in local livelihoods for at least 5,000 years.

Read more about what early life in Ica and how archaeobotanical studies have helped reveal the past

Plants of Ica

Cleistocactus sp.The project has recorded over 500 plant species in Ica with around 14 % unique to the Peruvian south coast, many of which are rare. Perhaps due to extreme conditions, there are less than twenty native tree and shrub species in Ica. The majority of species are smaller plants of the Graminae, Compositae, Leguminosae, Solanaceae, Malvaceae and Cactaceae families. Besides the keystone species - Huarango (Prosopis limensis), other important native tree species across the vegetation types include: Espino (Acacia macracantha), Guayajo (Capparis avicennifolia), Palo verde (Parkinsonia praecox), Uña de gato (Parkinsonia aculeata), Sauce (Salix humboldtiana), Molle (Schinus molle) Tara (Tara spinosa) and Maitén (Maytenus octogona).

In the most hyperarid areas the vegetation (xerophytic) includes Calato (Bulnesia retamo), Pate (Orthopterygium huaucui) and Huanarpo macho (Cnidoscolus peruvianus), often associated with columnar edible fruit-producing cacti such as Ulluquite (Neoraimondia arequipensis). Other larger species are so rare and the vegetation so long-degraded that it is difficult to assess their probably much wider and more prevalent former presence.

For more information see Plantas y Vegetación de Ica

Vegetation types of Ica

Vegetation type

Key woody species

Huarango dry-forest (0 – 550 m)

Acacia macracantha, Prosopis limensis, Pluchea chingoyo, Schinus molle, Vallesia glabra.

Riparian forest and scrub (0 – 600 m)

Acacia macracantha, Baccharis lanceolata, Salix humboldtiana, Tessaria integrifolia.

Prosopis dune forest (50 – 550 m)

Prosopis limensis, Tillandsia spp. (in fog areas).

Cactus scrub forest (600 – 1,500 m)

Acacia spp., Armatocereus procerus, Capparis avicennifolia, Maytenus octogona, Neoraimondia arequipensis, Scutia spicata, Tara spinosa, Tecoma fulva.

Huaycos — ephemeral streams or wadis (0 – 650 m )

Capparis avicennifolia, Galvezia fruticosa, Grabowskia boerhaviifolia, Parkinsonia praecox, Prosopis limensis, Schinus molle, Tecoma fulva.

Xerophytic Scrub (600 – 1,800 m)

Bulnesia retama, Cnidoscolus peruvianus, Orthopterygium huaucui, Haageocereus spp.

Lomas (600 – 1,100 m)

Krameria lappacea, Nolana spp., Stipa pachypus, Tillandsia spp.

Locally dominant Tamarix INVASIVE (0 – 500 m)

Tamarix aphylla.

Saltmarsh and wetlands (0 – 480 m)

Cyperus spp., Distichlis spicata, Equisetum giganteum, Salix humboldtiana, Tessaria integrifolia, Typha domingensis.

Bosque de acequia y huerta – woodland on irrigated floodplain and small agroforestry holdings (20 – 1,000 m)

South coast plant crops in association with Acacia macracantha, Annona cherimola, Inga feuillei, Pouteria lucuma, Prosopis limensis (also Mangifera indica, Carya illinoinensis and other non-native introductions, many with locally developed varieties).

Microphytic and cryptobiotic communities (in biological crusts)

Lichens, mosses, algae, cyanobacteria and fungi.

The Huarango tree

Ancient huarangoThe Huarango tree (Prosopis limensis) of Ica is the keystone species underpinning biodiversity and ecosystem in the region. It has also provided food, forage and fuel resources for local people for at least 7,000 years. Huarango trees capture moisture from fog in winter, and their exceptionally long roots (sometimes over 50 m) are able to tap deep groundwater, making life possible in the desert.  Sadly Huarango forest is on the edge of extinction: a situation reflected by its national classification as threatened and by the regional government by-law making all Huarango deforestation illegal (Ordenanza Regional 0009, 2007 GORE, Ica).

The Huarango is the primary producer, providing invaluable ecosystem services including soil fertility, desalination, climate improvement and a key refuge for animals in desert areas e.g. rare birds such as the slender-billed finch (Xenospinus concolor). The importance of conserving this resource is widely recognised in Peru and although legal measures have been put in place to control its destruction, enforcement is weak. Some local communities are striving to highlight the issue and protect veteran trees.

Traditionally the Huarango was seen as the tree of life, woven into mythology since pre-Columbian times. By 2004 the demand for fuel to commercial supply grills and alcohol distilling industries meant most old-growth Huarango forest had been destroyed. A further problem for the remaining Huarango has been insect plagues: iIn 2003 two such plagues began to defoliate forest across the region. The project identified productive plague-resistant varieties from a number of locations in Ica and collected seed to produce seedlings for planting programmews. Today, through the project schools programmes and the Huarango festival, as well as the emergence of a more environmentally concerned generation, there is a greater cultural appreciation of the Huarango by the many new migrants into the region.

Huerta

Huerta'Huerta' is a forested kitchen garden that is seasonally irrigated. In Ica many huertas have pre-Colombian origins, providing food and medicine for hundreds or maybe thousands of years. They also support native biodiversity and provide sustainable resources such as fertile soil and fuelwood. The huertas of Ica include a wide range of priceless native varieties of fruit trees such as Guanábana (Annona muricata), Cherimoya (Annona cherimola), Achiote (Bixa orellana), Ciruela de fraile (Bunchosia armeniaca), Pacay (Inga feuillei), Matico (Piper aduncum), Lúcuma (Pouteria lucuma), Guava (Psidium guajava), Boliche (Sapindus saponaria), Tara (Tara spinosa) and edible tubers such as Achira (Canna edulis), Yuca (Manihot esculenta). Established introduced trees (some perhaps archeophytes) include Zapote blanco (Casimiroa edulis), Leucaena (Leucaena leucocephala), Frijol de palo (Cajanus cajun), Pecan (Carya illinoinensis), Piñón (Jatropha curcas), Mango (Mangifera indica), Cinamomo (Melia azedarach),  Platano (Musa paradisiaca), Tuna (Opuntia ficus-indica), Palta (Persea americana), Granado (Punica granatum), Cirula (Spondias mombin) and Tamarindo (Tamarindus indica), amongst others.

Despite the widespread desertification in Ica the wild and domesticated huerta species offer extraordinary resources to provide for livelihoods, habitat, ecosystem and for adaptation to climate change. The project is working now to help conservation of locally adapted varieties that are being lost as traditional huertas are abandoned or converted.