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Foothills/Transition Zone

La Condamine led the  first scientific expedition to Latin America where he measured the circumference of the earth at the equator.

Alexander von Humbolt followed.  He  was in many respects the first modern Latin American and first modern geographer.

In his travels he had a thermometer, so he could measure temperature patterns, and a barometer to measure air pressure.  He invented the discipline of biogeography with his correlations of temperature, altitude and life somewhere around 1807.  Humbolt wrote of the relationship between climate and vegetation and for his pioneering work he has been called the "Father of Plant Geology".

C. Hart Merriam studied the relationship between mean annual temperature and distribution of flora and fauna in the western United States. He recognized that similar zones or belts of vegetation occurred with both increasing latitude and increasing elevation. He called these belts Life Zones.


Merriam's Life

Modern Vegetation Zone
Elevation / Range 
  ( Feet)  
Alpine Tundra
11,500 -12,700
35" - 40"
Spruce-Fir or Subalpine Conifer Forest
9,500 -11,500
30" - 40"
Canadian - Montane
Mixed Conifer Forest
8,000 - 9,500
25" - 30"
Ponderosa Pine Forest
6000 - 8,500
18" - 26"
Upper Sonoran
Pinyon-Juniper Woodland Semi-arid grasslands Semi-arid scrub
3,500 - 6,500
10" - 20"
Lower Sonoran
Mojave, Sonoran or Chilhuahuan
100 - 3,500
3" - 12"

Communities are not random in their organization, nor are they merely a collection of plants and animals that have learned to tolerate living in proximity to each other. A true community is composed of plants and animals that depend on each other for their survival.

Communities may have sharp boundaries, but most show a gradual transition as one community ends and another begins. These zones of transition are called edges, or ecotones. They offer a mixture of the two adjacent habitats, and may offer more diversity than either of their own. The foothills are a classic ecotone,  mixing a little of the plains with the Rockies in this case.


One other fact that needs to be mentioned, is if the latitude is changed south for instance, the piney transition zone high in the western part of Anza-Borrego in Mexico will be similar to the lower foothills of the Sierra Nevada, while the Lower Sonoran zone of Borrego Valley is host to shrubs closely related to their Mexican Kin mountains far to the south. Temperature, altitude and latitude decide the plant and animal life to sustain.

Colorado has five Life Zones. Those life zones are Alpine,  Subalpine,  Montane, Foothills, and the Plains.

The Rocky Mountains extend over 3000 miles from Northwest Alaska to Northern Mexico.


The Foothills Life Zone

Some of the trees that grow here are yellow pine, scrub oak, grease wood, blue spruce and ponderosa pine. The foothills zone is a transitional zone where Ponderosa pine dominates. Aspen forests are found on lower elevation slopes of the Montane, lower and upper foothills habitat.

Trees are widely spread because extensive root systems compete for available water.

Some of the flowers are the grizzly bear cactus, yellow evening primrose, lamberts loco and aster.

Birds are humming birds, chickadees, and bluebirds.

Insects found in the foothills zone are, Blue Darner  Dragonfly, Bumble Bee, Civil Blue Damselfly, Convergent Lady Bug, Harvest Ants, Honey Bee, Monarch Butterflies, Mosquito, Mountain PINE beetle, Mourning Cloak, Plains Lubber Grasshopper, Praying Mantis and the Yucca Moth.


Atlas of Nevada Mountain Ranges:  Vegetation,  David A. Charlet 1/7/1998

Foothills Zone:  dr. Alex Vargo 2002

Links:  Life on Earth - Biomes

 All photos on this page ©2004 by Carol Henderson

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