Local names:
English (tamarugo)
Prosopis tamarugo is a deciduous open-crowned tree up to 18 m tall, the trunk to 80 cm in diameter; with a dense mat of lateral roots and deep taproot (to 6 m deep on tree 15 m tall). Crown globe-like and irregular in shape; fissured bark, dark grey. Leaves unijugate, the pinnae 3-4 cm long or less, with 10-15 pairs of leaflets; leaflets linear obtuse or acutish, 4-8 mm long. Flowers golden yellow, in long axillary cylindrical spikes. Stipules spiny, 5-38 mm long. Brown calyx 1.5 mm long; corolla 4-5 mm long; ovary villous. Pod arcuate, turgid, brown or stramineous, 2-8 cm long, 2-3.5 cm in diameter with ca 6-8 seeds embedded in a brownish edible pulp, seeds ovate, 3-4.3 mm long.
Ecology
Found on salty-sandy or clay loam soils, occasionally with a 40 cm salt encrustation, ranging from warm temperate desert to thorn steppe through subtropical desert to subtropical thorn forest life zones. The climate is the normal desert climate; the most biologically significant factors are: high day-time temperatures, a great day-to-night temperature range, almost total lack of rainfall, occasional mist, relatively low humidity and intense sunlight. If introduced into more favourable climates elsewhere, this species might spread out of control and become a noxious weed.
Native range
Chile
Tree management
Plantation spacings in the Tamarugal Pampa (Chile) are at 10 x 10 m and 15 x 15 m, taking into consideration the tree's growth and its function as fodder. Two types of pruning are normally employed, the long pruning, to increase fruit yield and, secondarily, to increase foliage thickness. The other pruning method, short pruning is aimed at adding vigour to the tree. This enables the formation of great foliar mass and increase in fruit production. The tree coppices readily.
Seed storage behaviour is orthodox.
Found on salty-sandy or clay loam soils, occasionally with a 40 cm salt encrustation, ranging from warm temperate desert to thorn steppe through subtropical desert to subtropical thorn forest life zones. The climate is the normal desert climate; the most biologically significant factors are: high day-time temperatures, a great day-to-night temperature range, almost total lack of rainfall, occasional mist, relatively low humidity and intense sunlight. If introduced into more favourable climates elsewhere, this species might spread out of control and become a noxious weed.
Abundant natural regeneration has been recorded in periods following heavy floods, apparently because the fruits are carried by water, and destroyed in the process, with a subsequent mechanical scarification of the seed. Once the waters recede, seeds settle and begin to germinate profusely. Artificially, propagation is through nursery-raised seedlings. Germination is very irregular and slow due to the hardness of the sclerechymatic tissue and therefore it is necessary to make the seeds undergo a mechanical or chemical scarification process to improve germination. The seeds are treated with conc. sulphuric acid for 8-12 min. Keep seedlings in nursery 3 to 5 months, until they are 8 to 10 cm tall. Bark grafting has shown promising results in tamarugo (80% establishment).
The potential value of the tamarugo was noted as early as 1918 when Maldonado, a forest inspector called for a tamarugo forest preserve, considering it most important for the Chilean desert. It has the promise for reforesting deserts, especially those with thick surface-salt encrustation. Man-made tamarugo plantations are being introduced in the Tamarugal Pampa which are transforming the absolute desert ecosystem into an agro-ecosystem. The result, is a noteworthy increase in overall productivity in one of the most inhospitable regions of the world.
Tree produces abundant fodder, palatable to sheep, cattle and goats. It is said that older stands will support 26 sheep per hectare. Care must be taken that they do not destroy the lowest branches, which are important in the plant’s water economy, because they shade the dense lateral root zone near the soil surface.
Apiculture: In its natural habitat, imported Apis mellifera has served as a good pollinator as well as honey producer from the foraging.
It is used as fuelwood. In the part of the Atacama Desert in Northern Chile, the tamarugo stands are so over-exploited for firewood that they have been reduced to scattered stands.
Timber: The wood is used for furniture, although it is very heavy and difficult to work because it is very hard.
Nitrogen fixing: P. tamarugo is an efficient atmospheric nitrogen- fixer, where it grows.