FRST 211 lesson 7 - Forests and Soil Water Balance

Six Forest Formations

• Tropical Moist Forest

• Warm temperate forest

• Cool temperate forest

• Tropical dry forest

• Boreal forests

• Cool temperature forests

• Mediterranean scrub

• Tropical Moist Forest

• Tropical Dry Forest

• Cool Temperate Forest

• Boreal Forest

Cool temperate forest

Mediterranean scrub

Soil Water Balance formula

P (Precipitation) = E (Evapotranspiration) + (Change in soil storage) + R (Surplus runoff)

Evapotranspiration

• Evaporation of water from plants and trees

  (Transpiration (Exiting of water via stomata + evaporation)

Potential Evapotranspiration (PE)

• Ideal rate that would occur if compete plant cover and unlimited water

• Measures water need

• Represents energy (sunlight) availability

Actual Evapotranspiration (AE)

• Rate that actually occurs given availability of biological usable energy and water

• Measures water use

• Represents water availability

Water Deficit (D)

• When available water is less than PE

• Leads to AE<PE

• Deficit= PE- AE (Or more broadly, PE- Precipitation)

Describe the four stages in a soil water budget graph

• Water surplus (At this stage, precipitation exceeds actual evapotranspiration, allowing there to be a surplus of water.)

• Water Deficit Ground Store Depletion (At warmer/higher temperatures in the summer, actual evapotranspiration exceeds precipitation, resulting there to be a deficit of water as the groundwater is dried up and used up quickly.

• Water Deficit Ground Store depleted: (At this third stage, water is used up in the ground due to evapotranspiration exceeding precipitation.)

• Water Surplus Ground Store Recharge (Eventually in winter temperatures, water is being restored to the ecosystem.)

Subsolar point

• The point on the earth where the sun is perceived directly overhead

• From 0 to 23.5 degrees, beyond 23.5 degrees it is beyond the subsolar point.

Physiognomy of Southern Ontario vs. Coastal British Columbia

Southern Ontario

• Mid-latitude broadleaf

• Limiting Factors (Energy)

• Adaptations

• Winter deciduous - snow and drought protection

• Divergent branches at top (decurrent)

Coastal British Columbia

• Temperate rainforest

• Limiting Factors

• Water (in summer)

• Adaptations

• (Evergreen- chemical and physical drought adaptations)

• Divergent branches at bottom (excurrent) - access to low angle light, shedding snow

Transpiration

• Exiting of water via stomata

Tropic of Cancer

• 23.5 degrees North above the Equator

Tropic of Capricorn

• 23.5 degrees below the equator

Vernal equinox

• When the Sun is exactly above the Equator and day and night are of equal length.

Summer solstice

• The two moments during the year when the path of the Sun in the sky is farthest north in the Northern Hemisphere

Winter solstice

• Shortest and longest night of the ear, where the un reaches the southernmost point in the sky.

Excurrent tree form

• Present in gymnosperm trees, the bottom branches are longer than the ones higher than it forming a cone-like shape.

Decurrent tree shape

• Present in angiosperm trees, this is when the tree crown branches are usually pointed upwards, and the crown is much higher along the stem of the tree compared to an excurrent tree form tree crown.