Topic 15a:

Montane Forests - Ponderosa Pine

Announcements:

Lab tomorrow! Trip to Vallecito Reservoir, Forest & Fire History

    Meet in our lab classroom to pick up equipment at 12:15; we will drive to site in 2 vans

    Return by ~5 pm

Learning Goals for Day:

Role of Fire in Western Forests - general

Ponderosa Pine/Oak & Douglas Fir Forests

    Nature of forests

      Species Composition:

                Dominant species

                Indicator species

                Keystone species

    Role of disturbance

Ponderosa Powerpoint

Question:

Why are there more fires in Western forests than in Eastern forests (in North America)?

Explore this question in greater depth...

Implications of your response?

Expectations for forests at different elevations in the Southwest?

Montane Forests:

What is the environment like?

Who lives there?

Dominant Species:

Ponderosa Pine (Pinus ponderosa)

Historic Photo - Arizona (near Flagstaff), early 1900's

Indicator Species:

Abert's Squirrel

Stellar's Jay

Ponderosa Pine Forest -

Distribution:

Disturbance:

What disturbance regime would you predict for this habitat/life zone?

What does this forest look like? 

    sketch a plan view  -

before the 1800's vs. now or during the late 1900's (before our recent spate of fires in Ponderosa)

Closing Question:

Re-visit our opening question -

Why are fires more common in western forests than eastern ones?

        differences in moisture

Draw a horizontal line on your original carbon paper below your initial response.  Put your notes aside, and think about this:

Explain in your own words the significance of your first response.  How does limited moisture in the west affect the removal of woody debris, compared with how that debris is recycled in wetter eastern forests?

    In eastern forests, where it is more moist, the woody debris that accumulates on the forest floor is removed/recycled via decomposition - it rots and goes back into the soil.  In the west, where it is much drier, decomposition is very very slow, so there is potentially a lot more build-up of woody debris on the forest floor.  This litter becomes the fuel that supports forest fires, and it is fire that recycles & removes the debris in dry western forests and returns the nutrients to the soil.

And - what might you expect to see changed after 50 years of (effective) fire suppression in the Ponderosa Pine forest type?