Class 8 - montane forest Flashcards
(58 cards)
What is the range in vegetation type?
From dry woodland to extremely wet forest
Why are they one of the most threatened in the world?
Beacuse of humans
Why is the cloud forest the most diverse and important?
Filters global air so they seize and incorporate water and nutrients from mist and fog – more diverse than lowland forest
What lattitudes are montane forests at?
Found only between northern latitude 23 degrees in Mexico and 25 degree southern latitude in Argentine – and only in mointains
Which altitudes do they occur at?
Occur between 500 and 4000 m, majority between 1200 and 2800 m
Where do cloud forests occur?
Cloud forests occur in a narrow belt where there is persistent, frequent or seasonal cloud cover at vegetation level
What do cloud forests do to the atmosphere?
They cause a conciderable increase in atmospheric humidity = horizontal precipitation
What are the most important environmental factors determining TMF?
Horizontal presipitation, reduced photosynthesis due to solar radiation, periodic water shortage, temperate changes, reduction in evapotranspiration rate, exposure to strong winds, limited nutrient uptake
What are the main vegetation differences compared to lowland forest?
Reduced tree stature, increased stem density, gnarled trunks and branches, dense crowns
What covers trees in TMF?
A complex mosaic like assemblage of epiphytes – plants that obtain water directly from the atmosphere (orchids, ferns, mosses, algae, fungi) blankets the surface of trees and shrubs
What does the cover of epiphytes do for trees?
Contributes to an enormous extra above-ground biomass which can retain more water from clouds
Where do the most developed TMF occur?
Northern Andes
Why do TMF occur at higher elevations on taller mountains?
It is mainly associated with a lowering in the level at which clouds form, the greater the humidity at the mountains base, the lower the cloud level occurs
What are the temperature and rainfall ranges?
Annual temps between 8 and 20 degrees, rainfall between 500 and 10,000 mm, mostly between 1000 and 3000
What characterises the soil?
Acidic, peaty, yellowish, with organic upper layer – soil characteristics correlate strongly with plant distribution
Why do people deforest TMF?
Deforestation has happened for timber, fuelwood, charcoal, made into pastureland = severe land degradation
How much mountain landmass does TMF cover globally?
30%
What occurs above the treeline?
Above the tree-line occurs a treeless, alpine, cold, wet, misty biome, often dominated by giant stem rosette plants, shrubs, forbs, grasses, bamboo, mosses, lichens
Example of a tree in TMF?
There are small, flattened, bonsai-like trees which have curved trunks due to soil creep and slopes – very close together
What are the max canopy heights?
Max canopy height between 7 m and 20 m
Example of how temperate trees and tropical trees grow together?
In Costa Rica for example, oaks grow and below is a sub-canopy layer with many tree species of both tropical and temperate origin
At what elevation do temperate plants start growing?
2000 m
What happens in seasonally dry TMF?
There are some seasonally dry montane forests, where pine trees dominate and the forest experiences frequent drought and fire
Where is there the most species richness (latitude and altitude)
Species richness decreases with latitude, and is highest at mid-altitude elevations
