Table 2 Definitions of South American dry biomes
Biome | Annual rainfall (mm/year) | Length of dry season (months) | Dominant plant families | Physiognomy of vegetation | Notes on flora | Soils | Natural fire cycles | Frost |
|---|---|---|---|---|---|---|---|---|
Seasonally dry tropical forests [45] | < 1,100 | 5-9 | Leguminosae, Bignoniaceae, Euphorbiaceae, Cactaceae, Bromeliaceae | Open to closed canopy forest | Adaptations to drought, scarcity of perennial grasses | Fertile, well drained, shallow soils. pH 6-7 | Absent | Absent |
Savannas | 800-2,200 | 3-5 | Leguminosae, Myrtaceae, Vochysiaceae, Poaceae, Cyperaceae | Open to wooded grasslands | Fire adaptations in most plants, dominance of C4 grasses | Poor, Al rich, well drained, deep soils. pH very acid (~5) | Regular | Absent |
Chaco | 450-1,200 | c. 5 (variable) | Leguminosae (esp. Mimosoideae), Anacardiaceae, Cactaceae, Poaceae, Bromeliaceae | Open to closed canopy forest, interspersed with occasional savannas | Frost and salinity tolerant species with temperate affinities | Saline. Sometimes very alkaline in depth (up to pH 8-9) | Occasional | Regular, rarely snow |