Soils
Cryptogamic soil or cryptobiotic crust is very fragile and is vital to some prairie plants and soil biota. Cryptogams form a spongy layer that helps protect soil from erosion, absorbs moisture, and provides nitrogen and other nutrients for plant growth. During drought and frost, the cryptogamic crust uplifts and cracks. Cracks in the layer can provide germination sites for seeds from grasses and forbs. Reference: Fact sheet developed and funded by an Eisenhower Grant to the Partnership for Arid Lands Stewardship. Written by: Christine Sandahl.
Below are photos of cryptogamic soil at Spring Creek on exposed caliche or limestone.. This cryptogamic crust is the dark bumpy soil prevalent in drier areas of Spring Creek outside the forest and covers the surface of soil between grasses, shrubs, and flowering plants. This fragile crust is made up of mosses, lichens, algae, and bacteria and a microcosm of other inhabitants such as mites, springtails, nematodes, and other biota.
Jelly Fungus Moss with sporophytes cryptogam cryptogam
Also present are
jelly fungi (ear fungus) including
Auricularia species - Ear Fungus which has
gelatinous fruitbodies contorted into strange shapes
like ears or raisins. In dry periods, it is a crusty blackish growth on
exposed caliche soils and is easily missed by the casual observer. During rains,
however, Tree-Ear absorbs water, and expands to look like a human ear.
Tall grasses and forbs typically cover most prairie soils, but
cryptogams can be found on exposed outcrops as well as on old gravel pits along Spring Creek. Cryptogamic
soils are generally more western and in more arid climates, although they do
occur in Florida.
Above right: Cryptogams after a rain (click on to enlarge)
Above : Cryptogams during dry weather.
Succession on shallow soils and exposed rocks:
These soils were most likely maintained by periodic wildfires. The shallow soil depth limits growth to cryptogams and a few species of forbs and grasses. Once organic matter is built up, the cryptogamic stage typically succeeds to moss-covered soil with Woolly Ironweed, Barbara's Buttons, Queen's Delight, Thelesperma, Yucca, Ratany, Winecup, Redroot or New Jersey Tea, Whitlow-Wort, Missouri Primrose, and other prairie species(see lower right photo). According to Shinners & Mahler's, "species seen in this type of setting in the northern Blackland Prairie (Grayson County) include Baptisia australis (wild blue-indigo), Callirhoe pedata (finger poppy-mallow), Eriogonum longifolium (long-leaf wild buckwheat), Grindelia lanceolata (gulf gumweed), Ipomopsis rubra (standing-cypress), Linum pratense (meadow flax), Marshallia caespitosa (Barbara's-buttons), Oenothera macrocarpa (Missouri primrose), Paronychia jamesii (James' nailwort), and Thelesperma filifolium (greenthread). At some seasons, these outcrops have the aspect of barren eroded rock; in the spring, however, they are covered with spectacular displays of color."
Shinners & Mahler's Illustrated Flora of North Central Texas, 1999, George Diggs, Jr., Barney L. Lipscomb, and Robert J. O'Kennon, Austin College & Botanical Research Institute of Texas (BRIT).
Effects of fire on lichens as well as other community species is described in the Forest Service Fire Effects Information database. The FEIS database contains synoptic descriptions, taken from current English-language literature of almost 900 plant species, about 100 animal species, and 16 Kuchler plant communities found on the North American continent. The emphasis of each synopsis is fire and how it affects each species
More infomation on soil crusts can be found at the Biological Soil Crust page by the Bureau of Land Managment, U.S. Geological Survey, and National Park Service.
Effects of cattle grazing on cryptogamic soils can be found at: http://www.rangenet.org/directory/hudakm/overview.html
The Rhizosphere
In many native plant communities such as Spring Creek Preserve, a significant
portion of the total biomass is underground...for example, up to 70% of the
biomass of a tall-grass prairie is below ground. The area below ground where a
plant's roots interface with the soil is called the rhizosphere. The
rhizosphere is an area where symbiotic associations
between bacteria, fungi, grass rhizomes, forb roots, and other soil biota take
place. Mycorrhizal fungi and nitrogen-fixing bacteria form mutually beneficial
relationships with specific plant hosts. The microbial community and activity
around a plant's roots creates what some soil scientist refer to as living
soil. The deeper a plant's roots go the deeper the living soil. With extensive
deep root systems, native plant species help stabilize the soil column and
create an environment favorable to building fertile soils rich in organic matter
with a diverse soil biota.
Mycorrhizal Fungi (Soil Fungi)
To one degree or another, most plants in their natural habitats function under
the influence of a special groups of soil fungi known as arbuscular mycorrhizal
fungi ("AM fungi" or AMF). Mycorrhizal fungi associate with and connect to the
roots of plants. The plant provides the fungi's sole source of carbon, in the
form of simple sugars exuded by the roots. The fungal hyphae become an
extension of the plant's roots, increasing the
root's absorptive area by 10 to 10,000 times. A plant's relationship with
mycorrhizal fungi brings additional benefits. The fungi help to break down
nutrients locked away in the soil, making them available to the plant.
Mycorrhizal fungi also help plants to be more drought and disease resistant, and
improve soil structure, making them more porous.
It is estimated that 90% of all plant species from some type of symbiotic
realtionship with soil fungi. There are many species of mycorrhizal fungi. Some
plants form associations with only one specific species, while others can form
associations with a variety of species. Habitats of orchids, for example, by
determined by the habitat of their associated fungus. Orchids require the
relationship with a fungus for their existence. The relationship is essential
for the germination in the wild and is essential for a few orchid species
throughout life. Many species within the family Scrophulariaceae and
particularly with the genus Castilleja, or Indian Paintbrush, is considered to
be a facultative root parasite or hemi-parasite...the only way for a paintbursh
to survive is to stick it's tubes, called "haustoria"
into the roots of a host plant. Studies have also shown that species in the
family Poaceae benefit greatly from mycorrhizal colonization in termsof growth
and nutrient acquisition. Phosphorus nutrition of grasses in tallgrass
prairies is immediately tied to fungi.
The mycorrhizae community of soils is sensitive to disturbance. In many
man-made landscapes we have reduced or eliminated healthy diverse populations of
mycorrhizal fungi. With the heavy use of fertilizers and pesticides, the
compaction and paving of soils on construction sites, off-road use of vehicles,
and loss of topsoil through tillage and erosion
the population of these beneficial fungi have greatly declined or been
eliminated in many areas, particularly agricultural and urban landscapes.
Adapted from JFNew Native Plant Nursery 2002 Catalogue
Soil Biota links
National Soil Survey Center - Soils & Science Web Sites
Tardigrades or "Water Bears"
False Earth Star
Although not cryptogams, false earth stars are sometimes found in nearby areas of shallow soil during fall. Other interesting inhabitants include a camouflaged grasshopper which blends in with the Austin chalk...it is probably the Three Banded Grasshopper, Hadrotettix trifasciatus.
Special thanks to Barbara Keeler, US Environmental Protection Agency, for her discovery of cryptogamic soils at Spring Creek.
This web site was created by Derek Hill
E-mail comments, suggestions, and questions to
kinglet32@yahoo.com
01/10/2008