In lieu of an abstract, here is a brief excerpt of the content:

INTRODUCTION Grasslands constitute the most imperiled and least protected biome in North America, and the area of native prairie has declined rapidly in the late nineteenth and twentieth centuries because of agricultural pressure (Weaver and Fitzpatrick 1934). As a result, much recent scienti ¤c research has dealt with reestablishing and maintaining prairie remnants (Miller 1998; Anderson and Roberts 1993). Individual or combined effects of ¤re, grazing, mowing, and fertilization on prairie structure and function (Collins 1992; Collins et al. 1998; Howe 1994, 1995; Turner et al. 1997; Wilson and Shay 1990) are very important issues to conservation managers of prairies. Fire and herbivory are primarily responsible for the origin and maintenance of North American tallgrass prairie ecosystems (Knapp and Seastedt 1998), and some type of disturbance is required to halt succession and keep woody vegetation from encroaching on grasslands. The type and frequency of disturbance , whether by ¤re, mowing, or grazing, are key factors in determining prairie community composition (Collins 1992; Hartnett et al. 1996). Disturbance regimes also affect competitive interactions and therefore species composition (Wilson and Shay 1990). Managers of southeastern prairie ecosystems bene¤t from research into the responses of plant guilds and species to disturbance regimes by using that research in their decision-making processes. In concert with their knowledge of natural history, hard data reveal patterns of guild and species response to form management regimes. Short-term ecological studies are only snapshots of the larger scheme, but they document and remind conservation biologists of past events and pat14 Plant Assemblage Response to Disturbance at a Blackland Prairie Restoration Site in Northeastern Mississippi Timothy Schauwecker and John MacDonald terns. This study is one such snapshot, intended to compare two disturbance regimes (mowing and burning) in a small prairie undergoing restoration. The patterns that emerged from two years of study add to the resources that prairie managers currently draw upon in the decisionmaking process. STUDY AREA The Osborn Prairie is located in northeastern Oktibbeha County, Mississippi (Township 19 North, Range 15 East, Section 16) (Figure 14.1). The 25-ha tract is held in lease by the Starkville Public High School as a teaching aid for general science and biogeography classes and for the purpose of restoring and maintaining one of the best blackland prairie relics in the state of Mississippi (Wiygul et al., this volume). The site consists of gently rolling swales and uplands, dominated by unstable soils underlain by the Demopolis chalk formation of the Upper Cretaceous Selma group. The soils are high in montmorillonite clay particles and calcium carbonate and are moderately to highly alkaline . Soil series found on site are eroded Kipling silty clay loams of 2–5 percent slope, eroded Sumter and Binnsville silty clay loams of 2–5 percent and 5–8 percent slopes, respectively, and gullied Sumtercomplex soils of 5–20 percent slope (Brent 1973). The ¤ve distinct plant assemblages found at the site include (1) swales dominated by green ash, Osage orange, and hackberry; (2) cedar woodland; (3) native grassland on uplands dominated by little bluestem and juvenile eastern redcedar ; (4) Schizachyrium scoparium/Sporobolus vagini®orus–dominated prairie on eroded, alluvial soils that have been redeposited; and (5) pine/calciphile hardwood on ridgetops with the deepest soils. The upland prairie and alluvial prairie grasslands and cleared cedar woodland (assemblages 2–4 from above) were chosen for study to assess burning and mowing as restoration techniques. The upland prairie type is open, “good” prairie found on hilltops both in a power line right-ofway and scattered throughout the site, mostly where soils are thin and rates of succession are slow. Alluvial prairie is found where eroded chalk and upland soils have been redeposited in the swales downhill from the erosion. Soils in this habitat are very high in carbonate clay; they are very dry and prone to cracking during the growing season. Cleared cedar woodland occurs anywhere that mature cedars were removed in the spring of 1998 as a ¤rst step toward expanding the prairie habitat. In the absence of disturbance, all grassland areas would eventually succeed to cedar woodland and/or pine/hardwood communities (Schauwecker, unpublished report). Plant Assemblage Response 247 FIELD METHODS Species presence was recorded in ¤ve 0.25-square-meter quadrats per treatment plot for a total of 360 quadrats (¤ve quadrats plot−1 × six plots block−1 × four blocks habitat−1 × three habitats). Species abundance was measured via a nondestructive pin-frame method (Kent and Coker 1992). This method was chosen as a way to estimate...

Share