Vegetation Zones of Costa Rica
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Vegetation Zones of Costa Rica
L. R. Holdridge established a classification system for life zones in 1947 based on three types of climatic data:
- Potential Evapotranspiration Ratio (PET). This is measured as the environmental demand for evapotranspiration (evaporation + transpiration through trees), which is an index of the energy available to evaporate water and the wind available to transport water vapor from the ground up.
- Biotemperature, or an index of the temperatures above freezing. Adjusted to zero since to plants temperatures below zero are equivalent to those at zero, and the plants are dormant. The Critical line is the frost line.
- Humidity province. Based on mean annual precipitation in millimeters.
The combination of these three variables helps to classify life zones into 30 hexagonal groupings, and within each grouping are even smaller more specific zones that increase the total life zones on the planet into 116 types.
In Costa Rica there are twelve identified life zones primarily in the humid to superhumid range, in the lower righthand corner of Holdridge's diagram. These zones are fully described in a summary of Costa Rica's plant populations by Hartshorn (1983), and are reproduced in tabular form below:
| Costa Rica Life Zones | |||||||
|---|---|---|---|---|---|---|---|
| Elevation (upper limit) | Forest Type | Tree Features | Canopy Height | Epiphytes or Vines | Shrub Layer | Ground Layer | Other Features |
| 1000m | Tropical dry forest | Compound leaves, stout trunks, flat-topped crowns. | 20-30m | Occasional | Dense and thorny | Sparse/bare | Rubiaceae common in understory |
| Tropical moist forest | Wide crowns, light-colored bark. | 40-50m | Abundant | Palms | Bare, some ferns | Many lianas, long drip tips on leaves | |
| Tropical wet forest | Buttressed trunks, light-colored bark. | 45-55m | Relatively rare | Palms and giants herbs | Sparse, some ferns | Most species-rich life zone in Costa Rica | |
| 2000m | Tropical premontane moist forest | Umbrella crowns, flaky / rough bark | 25m | Rare | Woody, spiny plants | Sparse | Many trees crooked |
| Tropical premontane wet forest | Bark brown or gray, fissured, leaves on twig ends. | 30-40m | Present, many vines | Dense and thorny | Bare, some ferns | Most trees covered by moss | |
| Tropical premontane rain forest | Round to conical crown, thin bark | 30-40m | Abundant | Dense | Completely covered in ferns | Moss and epiphytes everywhere | |
| 3000m | Tropical lower montane moist forest | Rough bark, gnarled branches | 30-35m | Uncommon | Dense, large-leaved plants | Open, grassy | Most of the trees are oaks |
| Tropical lower montane wet forest | Thick flaky bark | 20-25m | Orchids, bromeliads | Dense, few palms | Ferns, vines, rotting leaves | Large coiled lianas common | |
| Tropical lower montane rain forest | Thick bark, compact crown | 25-30m | Orchids, bromeliads | Dense | Ferns, sedges, moss | Large-leaved vines | |
| 4000m | Tropical montane wet forest | Unknown | Unknown | Unknown | Bamboo | Unknown | Restricted to the southwest slopes of Volcano Irazu, lost in the 1963-5 volcanic eruptions, little data |
| Tropical montane rain forest | Short with rough bark | 25-30m | Orchids, bromeliads | Bamboo | Open | Woody vines with fleshy leaves | |
| 4500m | Tropical subalpine rain paramo | N/A | N/A | N/A | Mostly tree-like flowers | Mosses dominate | Bogs are present |
