Abiotic and Biotic Factors
Abiotic Factors
- Topography (Physical Features)
-- Mountains: High elevation impacts sunlight, temperature, clouds, and
precipitation
- Slope
-- Landslide - Impacts plant growth, destroys homes of animals, hurts
natural ecosystem by
erosion and movement
-- Root structures adapt to slopes
-- Animals adapting to slopes
- Soil
the ecosystem
- Effects what types of plants grow in that area due to nutrients, aeration, and
water content
- Rocks - Affect water flow throughout forest: speed and direction
- Water
be hurt
- Streams - Contain organisms that effect ecosystem; part of the food chain
- Water speed- Affects how organisms survive in rivers and streams, dispersal of
nutrients, plants, sediment, chemicals
- Natural stream obstacles: Blocks water from flowing easily, building up
sediment and change animals' natural paths
-- Logs
-- Leaves
-- Rocks
-- Man-made dams: Changes the flow of water, impacts organisms and
migration patterns, changes habitats
-- Precipitation- Necessary for maintenance of the ecosystem and provides
water to major rivers, the source of water for 20% of the Puerto Rican population
- Temperature - Affects rate of photosynthesis on plants
- Amount of Oxygen/Carbon Dioxide in the air - Affects growth of plants and survival of animals
- Sunlight/solar energy - Allows photosynthesis of plants and trees; important for the rest of the food chain to survive
- Wind (speed) - Affects seed dispersal and changes the density of the canopy; has an impact on the amount of sunlight
- Storms and Hurricanes
- Brings large amounts of precipitation quickly
-- Slope of the land and the absorption of the soil impacts how water is
absorbed or how water flows
- Hurricane Hortense - example
-- 1996- Rio Icacos watershed at southern part of El Yunque Forest - Pushed
as much soil sediment into river at one time, as a normal year would do
typically
- Hurricane Hugo - example
-- 1989: strong winds on main Forest route 191, opened up the canopy,
increasing sunlight. Sixty percent of the trees were damaged and 27% of
the Puerto Rican Parrot population was lost.
- Human Impacts (but not the abiotic humans)
endangering species and the ecosystem
- Automobiles- auto emission, oil, chemicals
- Noise- disturbs animals; affects food chain and ecosystem
- Litter- Hurts forest ecosystem by being eaten by animals and killing them;
leaving chemicals; creating water detours and blockages
- Hiking trails
-- Fragments forest and ecosystem
-- Forest visitors cause erosion and degradation of soil, disturb species and
litter
- Tourist buildings: prevent expansion of the forest, leak chemicals, artificial light,
litter, noise
- Roads – Prevent growth of plants, trees, absorb heat from the sun, and don’t
allow water absorption, creating runoff and fragmentation of the Forest
- Chemicals (from litter, or potentially fertilizers or industry in urban areas outside the forest
- Poisons rivers and water sources, killing organisms relying on water sources
and hurting food chain
- Damages soil, killing organisms living in it and making it unhealthy for trees
- Fire - destroys animals’ habitats and destroys plants and trees growing in the environment
_____________________
Biotic Factors
- Plants
-- Species: 225 in 144 genera and 59 plant families; 45 endemic to
Puerto Rico and 23 to the Luquillo Experimental Forest
--- The number of tree species in EYF > the number of species
in all other national forests combined
--- 10% of the tree species cannot be found anywhere else in
the world.
- Ferns
-- Species: 150 species in Luquillo Mountains
- Orchids
-- Species: 79 species in the Luquillo Mountains
- Classified Plants
-- Species: 38 species, including 24 trees, 2 shrubs, and 12 herbs
(US Forest service lists 8 plant species as endangered and 30 as sensitive)
- Animals: Less diverse than other continental forests because, El Yunque Forest is far away
- Mammals
-- 11 species of native bats b)
- Birds
-- 101 species, including 12 island endemics
- Reptiles
-- 19 species of native reptiles, including 8 island endemics
- Amphibians
-- 14 natives, including 8 island endemics
- Fish
-- 6 native species
- Classified animals
-- 13 species, including 1 bat, 1 snake, 5 frogs, and 6 birds (The US
Forest Service lists 5 animal species as endangered, 7 as
sensitive and 1 as threatened
- Human
- Natives
(Weaver 97)