Alpine wildflowers and 13,604' (4146m) Tijeras Peak, Great Sand Dunes National Preserve
is the highest ecosystem at Great Sand Dunes. Here, the conditions are too harsh for trees to survive, but wildflowers
, pikas, marmots
, and bighorn sheep
thrive in these challenging conditions. In Great Sand Dunes National Presrve, alpine tundra extends elevationally from about 11,700' (3566m) to 13,604' (4146m).
Skeletal trees hang on for survival at treeline
NPS/Phyllis Pineda Bovin
Krummholz means "crooked wood". Trees at the upper limit of their habitat range - 11,700' (3566m) are stunted and twisted due to high winds, snow, ice, short growing seasons, and shallow, poorly developed soils.
This is a transition zone between subalpine forest and alpine tundra, and an important refuge This is a transition zone between subalpine forest and alpine tundra, and an important refuge during storms for some mammals and birds who primarily live on tundra. Because bristlecone pine and limber pines grow extremely slowly, their small statures often belie true ages. Some are reported to be over 1000 years old.
Snowfields are often still melting into Lower Sand Creek Lake in early July.
There are five named alpine lakes and a few unnamed tarns in Great Sand Dunes National Preserve. Some of these lakes are in the transition zone between forest and tundra, at around 11,700' (3566m), while some smaller tarns are situated on alpine tundra.
These lakes and tarns provide habitat for trout and a few high-altitude amphibians, and are part of the mountain watershed of Great Sand Dunes.
Subalpine forests and meadows
Wildflower blooms peak during mid-summer in subalpine meadows.
capture heavy snow in winter and soaking rains in summer. The highest diversity of Rocky Mountain species of plants
can be found here. Subalpine forest extends elevationally from 9500' (2896m) to treeline at 11,700' (3566m).
View of the dunefield from 750' (229m) Star Dune.
with the tallest dunes in North America spreads across 30 square miles (78 sq. km), a unique high-altitude desert environment surrounded by the other ecosystems listed on this page. These dunes are a place of extremes: the sand surface can reach 150 degrees F (65 degrees C) on a summer afternoon, or drop to minus 20 degrees F (minus 29 degrees C) on a winter night. While the top few inches are often dry, these dunes are moist year-round, kept wet by ongoing precipitation. This 7% moisture content by weight allows species such as Ord's kangaroo rat
, Great Sand Dunes Tiger Beetle
, scurfpea, and blowout grass
to survive here. Many animals visit the dunes from other habitats, including elk, pronghorn, bison, coyotes, bobcats
, and raptors
. Find out more about the geology of Great Sand Dunes.
The southern boundary of the national park is County Lane 6, where a wet spring brought out these wildflowers in 2009.
Extensive grasslands and shrublands
surround the dunefield on three sides, from 7500' - 8200' (2286m - 2499m). Geologically, this region is referred to as the sand sheet
. It varies from wet meadows to cool-grass prairie to desert shrubland, depending on proximity to groundwater and soil type. Elk and pronghorn are common here
. Burrowing owls
nest in the ground, while other raptors float the skies searching for mice, kangaroo rats
, and short-horned lizards
Saltgrass can survive being surrounded by sabkha alkali deposits, similar to baking soda.
is a wetland region where groundwater rises and falls seasonally, leaving white alkali deposits on the surface. Inland saltgrass
is common in this area. Toads
can reproduce in sabkha wetlands when they are seasonally filled with sufficient fresh water. Shore birds such as the American avocet
hunt tadpoles and insects in the shallow water. The sabkha is at approximately 7500' (2286m) in elevation.
South Twin Lake is surrounded by bulrush that are taller than a person in mid-summer.
Wetlands speckle the San Luis Valley, and are important habitat for sandhill cranes, shore birds, amphibians, dragonflies, and freshwater shrimp. Grassland species such as elk also use these waters for drinking. The park's wetlands are at approximately 7500' (2286m) in elevation.