Common (Translated Scientific) Name: Tropical Montane Grassland & Shrubland Formation

Colloquial Name: Tropical Montane Grassland & Shrubland

Hierarchy Level:  Formation

Type Concept: Tropical Montane Grassland & Shrubland is dominated by shrubs and herbs with mesomorphic growth forms, predominantly tussock grasses, large rosette plants, shrubs with evergreen coriaceous and sclerophyllous-ericoid leaves, and cushion plants. Vegetation structure varies from grasslands, with few short woody growth forms, to a closed canopy of shrubs usually not taller than 1-2 m high. Spatially patchy vegetation structure is typical due to both substrate heterogeneity and human influence characterized by periodic burning and grazing. The majority of the area covered by this vegetation corresponds to types that occur on tropical mountains within or above the limit of continuous, closed-canopy forest or forestline and below the sub-nival elevations, from 3000 to 4500 m (i.e., páramo and puna). Annual precipitation varies with the site and aspect of the location, from 50 to 300 cm, and seasonality is related to the rainfall rather than to temperature. The main difference between this formation and its temperate counterpart is the diurnal fluctuation of temperature, which can be of 20°C or more in tropical high mountains (e.g., Andes, Africa), with no growth limiting season. Shrub and herbaceous vegetation of smaller tropical ranges (e.g., Central America, Southeast Asia and New Guinea) and on the summits of mountains of the Guyana Shield and the Brazilian planaltos (plateaus) are included here because they occur above the forest line (about 1600 m in the latter). True cryomorphic vegetation, super-páramo and higher elevation puna, are treated in the tropical alpine biome. They grow above 4300 m elevation up to the permanent snowline, with mean annual temperatures <3°C, and soils have cryomorphic features (such as cryoturbation). Physiognomic distinctions are mostly based on the ground, which is continuous here as compared to the low, semi-open coverage of the tropical alpine biome.

Diagnostic Characteristics: Herbaceous perennials (forbs and grasses) and small woody shrubs are predominant, with small rosette and large caulirosulate plants with arborescent habit also present. The overall structure varies from semi-open to almost 100% coverage. The vegetation structure has irregular horizontal canopy spacing, except for the vast expanses of grassland communities in some locations.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: In terms of overall physiognomy, this formation is closely related to 4.A.1 ~Tropical High Montane Scrub & Grassland Formation (F022)$$ that has been placed within 4. ~Polar & High Montane Scrub & Grassland Class (C04)$$, and many authors would place all of the vegetation described here in that formation (e.g., Quinn 2008). The main reason for this split is that in the Tropics, the true cryomorphic vegetation, super-páramo and higher elevation puna, are treated in 4.A. They grow above 4300 m elevation up to the permanent snowline, with mean annual temperatures <3°C, and soils have cryomorphic features (such as cryoturbation). Physiognomic distinctions are mostly based on the ground cover of the formation, which is continuous as compared to the low, semi-open coverage of the tropical cryomorphic formations.

Still, as defined here, 2.A.2 ~Tropical Montane Grassland & Shrubland Formation (F017)$$ often is found at elevations above 3000 m, which means that 2.A.1. ~Tropical Lowland Grassland, Savanna & Shrubland Formation (F019)$$ extends up to 3000 m. This may be problematic with respect to the use of Montane versus Lowland as used, though usually there is a forest band between the two. This formation is near to sometimes above the treeline, but many will associate montane with a mid-elevation forest zone, including lower and upper montane forests.

Similar NVC Types: No Data Available

note: No Data Available