Ecological dynamics

This site developed in wind worked alluvial or eolian deposits. The soils are fine sands with no organic matter and no clay particles so the development of horizons is limited. The reworking by winds has contributed to the sites undulating topography. These are young soils developmentally and age of sediments does affect the nature of plant communities to some degree. Some of these soils may have been unstable just a short time ago. There are instances of good plant cover existing now where 75 years ago there were naked dunes. Sandhills that have been stable for a longer period of time usually have the more diverse plant communities present.

The fragility of the site cannot be overstated. It is essential that good plant cover be maintained or the site will actively erode. The most stable site ecologically and the more diverse plant community is one of tall grasses, perennial forbs and shrubs. Shrubs are often the most stable and adapted plants especially in times of drought. When explorers and military expeditions crossed the plains in the early 1800’s, they noted the presence of sandhills with woody shrub vegetation. It is likely that with the help of natural fire from time to time, that a balance between shrubs and grasses was maintained. Fire would suppress the shrubs and for a time grasses would dominate until the shrubs became more competitive. This may have operated as a sort of cycle with an ebb and flow effect as to whether grasses or shrubs were dominant. Heavy grazing by livestock will reduce the tallgrasses and favor the shrubs. The tallgrass species are more susceptible to being damaged by grazing. Shrubs are resistant to grazing pressure and are generally not very palatable. Whatever the species growing on this site, it is almost certain that the best adapted will have deep, extensive root systems that can reach deep moisture far down in the soil profile. The ratio of grasses to shrubs in reference condition would vary from site to site but a good estimate of the range would be from (60% grass – 30% shrubs – 10% forbs) to a (45% grass – 45% shrub – 10% forb) composition. There are portions within the site where grasses dominate and places where woody plants dominate and they may not always be uniformly distributed. Grasses are not as drought tolerant as shrubs and cannot fully stabilize the site without some shrub cover. Of course, shrubs will increase when vigorous tallgrasses are removed from the community. A shrub dominated community may be very stable but diversity is limited and as wildlife habitat it is definitely less desirable.

As to the use of prescribed fire as a tool to restore balance within this community, extreme care should be taken. Sparsely covered dune areas should not be burned. The most advisable type of burn would be a late spring timed burn so the restoration of plant cover would be as quick as possible. Before entertaining the idea of burning at all, it is essential that the site be managed to achieve a high ecological condition so that recovery post burn can be as quick as possible. The possibility of significant wind erosion occurring is always a possibility.

Proper stocking and flexibility are essential. Judiciously applied brush management using labeled herbicides can be an aid in manipulating the balance between shrubs and grasses. Suppression rather than elimination of the woody plants should be the goal.

The major grass species occurring in the reference community are: sand bluestem (Andropogon hallii), little bluestem (Schizachyrium scoparium), giant sandreed (Calmovilfa gigantea), spike and giant dropseed (Sporobolus contractus and Sporobolus giganteus), with smaller amounts of switchgrass (Panicum virgatum) and Indiangrass (Sorghastrum nutans). Canada wildrye (Elymus canadensis) and needle and thread (Hesperostipa comata) are cool-season grasses that are more visible in years of above average winter and early spring moisture. There are several midgrasses present such as sideoats grama (Bouteloua curtipendula), sand lovegrass (Eragrostis trichodes), and sand paspalum (Paspalum distichum). Perennial forbs that are most prevalent are: western ragweed (Ambrosia psilostachya), catclaw sensitivebriar (Mimosa microphylla), bush morninglory (Ipomea leptophylla), pastel tephrosia (Tephrosia virginiana), Queen’s delight (Styllingia sylvatica), erect dayflower (Commelina erecta), and prairie spiderwort (Tradescantia occidentalis). Several annual forbs are also present with more occurring in growing seasons of abundant rainfall. Major woody shrubs are: sand sagebrush (Artemisia filifolia), skunkbush sumac (Rhus aromatica), sand plum (Prunus gracilis), Havard shinoak (Quercus havardii) and southwestern rabbitbrush (Chrysothamnus visidiflorus). There are usually few scattered trees present throughout the site such as hackberry (Celtis laegivata var. reticulata) and western soapberry (Sapindus saponaria).

If the site has a good diversity of plant species, there will be a variety of wildlife species that utilize the site as habitat. White tail deer, turkey, and Bobwhite quail are the main game species that utilize the site as habitat. A variety of small mammals, birds and predators can be found as well.

STATE AND TRANSITIONAL PATHWAYS (DIAGRAM):

Narrative:
The following diagram suggests some pathways that the vegetation on this site might take. There may be other states not shown on the diagram. This information is intended to show what might happen in a given set of circumstances; it does not mean that this would happen the same way in every instance. Local professional guidance should always be sought before pursuing a treatment scenario.