Composition, Classification and Species Response Patterns of Remnant Tallgrass Prairies in Texas

摘要: Thirty-five remnant upland grasslands within the Blackland, San Antonio, Fayette and Upper Coastal prairies were sampled for species frequency, foliage cover richness. PCA ordination cluster analysis used to ordinate classify these communities. The majority of are dominated by Schizachyrium scoparium with Sorghastrum nutans second most important species. Andropogon gerardii Bouteloua curtipendula increase in importance increasing soil clay content, organic matter pH decreasing total annual precipitation. Paspalum plicatulum becomes an secondary communities over acid Alfisols Prairie Vertisols Prairie. High precipitation ( > 90 cm) areas at northern end Blackland support a unique grassland Sporobolus silveanus Carex meadii as In this same area on found that Tripsacum dactyloides Panicum virgatum. Species respond independently continuously along climatic gradients except where locally sharp transitions occur between Vertisols. diversity did not vary significantly among Soil was positively correlated richness, which related slightly higher richness stands whici. have low pH, also generally lower values. INTRODUCTION Fort Worth, occupy N-S strip comprising approximately 8 million ha E central Texas (Godfrey et al., 1973) (Fig. 1). Native vegetation has largely been destroyed cultivation, overgrazing urbanization. Although several authors described (Dyksterhuis, 1946; Launchbaugh, 1955; Collins 1975; Butler, 1979; Diamond, 1983; Smeins 1983), no attempt made compare patterns community composition them. traditionally separated from other (Tharp, 1926; Gould, 1975), but lack quantitative data makes evaluation degree relationship impossible. This study provides soils uplands Fayette, Antonio prairies. These allow detailed to: (1) determine relationships communities; (2) evaluate species-to-species species-to-environment relationships; (3) clarify classification, (4) diversity. STUDY AREA Location extent. -The studied located 300 km wide 100 long To N borders Red River, whereas S grades into Gulf Coast marshes. eastern border is defined Post Oak Savannah, while western Cross Timbers N, Edwards Pla-