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F004 Tropical Montane Humid Forest Formation
Type Concept Sentence: Tropical Montane Humid Forest is dominated by broad-leaved evergreen trees, with increasingly small leaves and stems, often gnarly, with dense crowns as elevations increase. These forests are generally found within 23°N and S latitude of the equator between 1000 and 3500 m in elevation.
Common (Translated Scientific) Name: Tropical Montane Humid Forest Formation
Colloquial Name: Tropical Montane Humid Forest
Hierarchy Level: Formation
Type Concept: Tropical Montane Humid Forest is dominated by broad-leaved evergreen trees, with increasingly small leaves and stems, often gnarly, with dense crowns as elevations increase. They are generally found within 23°N and S latitude of the equator and typically between 1000 and 3500 m in elevation. Lower elevations contain a transition to 1.A.2 ~Tropical Lowland Humid Forest Formation (F020)$$. At the highest elevations, the trees may be <10 m tall (sometimes referred to as elfin woodland and scrub), and covered in bryophytes, ferns, and other epiphytic plants. Evergreenness varies from completely evergreen to semi-evergreen seasonal forests, in which around 25% of the main canopy may be regularly deciduous. Climates are more often cool, but without frost, with seasonal daily temperatures with minimal variation. Annual rainfall is relatively aseasonal and typically >100 cm, with any given month rarely receiving <60 mm.
Diagnostic Characteristics: Tropical Montane Humid Forest is dominated by micro- to mesophyll, broad-leaved evergreen trees (up to 25% deciduous trees), with a simple or two-layer structure, ranging from 5 to 30 m in height. Climates are more often cool, but without frost, with seasonal daily temperatures with minimal variation. Annual rainfall is relatively aseasonal and typically >100 cm, with any given month rarely receiving <60 mm. The proportion of precipitation that is from clouds is a defining factor, but is difficult to assess. Better defining characteristics are the amounts of epiphytes and ferns and where the epiphytes occur as well as canopy structure.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: The proportion of precipitation that is from clouds is a defining factor, but is difficult to assess. Tropical Montane Humid Forests resemble heath forests to some degree (Whitmore 1998), with their wet climate, but have smaller stems and leaves.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Tropical Montane Humid Forest is dominated by broad-leaved evergreen trees, with increasingly small leaves and stems, often gnarly, with dense crowns as elevations increase. Lower elevations represent a transition from 1.A.2 ~Tropical Lowland Humid Forest Formation (F020)$$ [see Table 1]. At the highest elevations, the trees may be <10 m tall (sometimes referred to as elfin woodland), and covered in bryophytes, ferns, and other epiphytic plants. Peat may form, sometimes with sphagnum mosses (Sphagnum spp.). These in turn may be replaced by a kind of "tropical subalpine forest" with very tiny leaves (nanophylls), as found in New Guinea and the Andes (Whitmore 1998). Treeline is typically reached between 3500 and 4000 m, where the vegetation transitions to "tropical high montane grassland and shrubland" (tropical "alpine" vegetation).
Table 1. Characters used to distinguish Tropical Lowland Humid Forest from the two types of Tropical Montane Humid Forest (after Whitmore (1998), Table 2.2, based primarily on Southeast Asian forests).
Table 1. Characters used to distinguish Tropical Lowland Humid Forest from the two types of Tropical Montane Humid Forest (after Whitmore (1998), Table 2.2, based primarily on Southeast Asian forests).
| Formation Criteria | Tropical Lowland Humid Forest | Tropical Montane Humid Forest |
| Canopy height | 25-45 m | 1.5-33 m |
| Emergent trees | Characteristic, to 60 (80) m tall | Often to usually absent, to 37 m tall |
| Pinnate leaves | Frequent | Rare to very rare |
| Principle leaf size class of woody plants | Mesophyll | Mesophyll or microphyll |
| Buttresses | Usually frequent and large | Uncommon, small or absent |
| Cauliflory | Frequent | Rare to absent |
| Big woody climbers | Abundant | Usually none |
| Bole climbers | Often abundant | Very few, frequent to abundant |
| Vascular epiphytes | Frequent | Frequent to abundant |
| Nonvascular epiphytes | Occasional | Occasional to abundant |
Floristics: No Data Available
Dynamics: No Data Available
Environmental Description: Climate: Climates are more often cool, but without frost, with seasonal daily temperatures with minimal variation. Annual rainfall is relatively aseasonal and typically >100 cm, with any given month rarely receiving <60 mm. The proportion of precipitation that is from clouds is a defining factor, though this is difficult to know in the field. Better defining characteristics are the amounts of epiphytes and ferns and where the epiphytes occur as well as canopy structure.
Soil/substrate/hydrology: Tropical Montane Humid Forest is typically found between elevations of 1000 to 3500 m, with the treeline typically reached between 3500 and 4000 m. But the boundary between lowland and montane forests occurs at different elevations depending on the "Massenerhebung effect" (Collins 1990, Richards 1996). This is a phenomenon whereby large mountains and the central parts of large ranges are warmer at given elevations than small mountains and outlying spurs. Thus Collins (1990) mapped the boundaries in the Caribbean, Central America, Madagascar, Australia, and Southeast Asia at 910 m, whereas in West Africa the boundary was set at 1200 m, in New Guinea at 1400 m, and in South America at 1800 m.
Soil/substrate/hydrology: Tropical Montane Humid Forest is typically found between elevations of 1000 to 3500 m, with the treeline typically reached between 3500 and 4000 m. But the boundary between lowland and montane forests occurs at different elevations depending on the "Massenerhebung effect" (Collins 1990, Richards 1996). This is a phenomenon whereby large mountains and the central parts of large ranges are warmer at given elevations than small mountains and outlying spurs. Thus Collins (1990) mapped the boundaries in the Caribbean, Central America, Madagascar, Australia, and Southeast Asia at 910 m, whereas in West Africa the boundary was set at 1200 m, in New Guinea at 1400 m, and in South America at 1800 m.
Geographic Range: Tropical Montane Humid Forest is generally found around the globe within 23°N and S latitude of the equator, typically between 1000 and 3500 m in elevation. It is found extensively in Central and South America, especially the Andes and parts of the Caribbean, and is uncommon in Africa (Cameroon and the eastern fringe of the Congo basin) and many mountain regions throughout the Indo-Malayan region.
Nations: AS,AU,MP,MX,PR,US,WS
States/Provinces: No Data Available
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.860262
Confidence Level: High
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 1 Forest & Woodland Class | C01 | 1 |
| Subclass | 1.A Tropical Forest & Woodland Subclass | S17 | 1.A |
| Formation | 1.A.3 Tropical Montane Humid Forest Formation | F004 | 1.A.3 |
| Division | 1.A.3.Eg Caribbean-Mesoamerican Montane Humid Forest Division | D228 | 1.A.3.Eg |
| Division | 1.A.3.Oa Polynesian Montane & Cloud Forest Division | D068 | 1.A.3.Oa |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Elfinwoods: biome-type 7 (Whittaker 1975)
= Tropical montane rain forests (Whitmore 1998) [Whitmore (Table 2.2) discusses the range of variation between lower and upper montane rainforests.]
= Tropical montane rain forests (Whitmore 1998) [Whitmore (Table 2.2) discusses the range of variation between lower and upper montane rainforests.]
- Collins, M. 1990. The last rain forests: A world conservation atlas. Oxford University Press, New York.
- Faber-Langendoen, D., T. Keeler-Wolf, D. Meidinger, C. Josse, A. Weakley, D. Tart, G. Navarro, B. Hoagland, S. Ponomarenko, J.-P. Saucier, G. Fults, and E. Helmer. 2015c. Classification and description of world formation types. General Technical Report RMRS-GTR-000. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.
- Richards, P. W. 1996. The tropical rain forest: An ecological study. Second edition. Cambridge University Press, Cambridge, UK. 600 pp.
- Whitmore, T. C. 1998. An introduction to tropical rain forests. Second edition. Oxford University Press, Oxford.
- Whittaker, R. H. 1975. Communities and ecosystems. Second edition. Macmillan Publishing Co., New York. 387 pp.