Tall dropseed occurs in all states except California, Nevada, Florida, South Carolina, New Hampshire, Alaska, and Hawaii [45,94,104,123,235,258]. However, it is most widespread in the Great Plains and the Midwest. It is common from Ohio and Indiana west through Illinois, Missouri, and Iowa to North Dakota [218] and South Dakota [55], south through Nebraska, Kansas, and Oklahoma to Texas. It is scattered in the southeastern [11,103] and northeastern [65,147,184,200,241] United States. It is even more patchily distributed in the western United States, including Utah [211], Colorado [251], Wyoming [57], and Montana [56]. Plants Database provides a distributional map of tall dropseed.
Composite dropseed is the most widespread of the 3 varieties, occurring throughout the species' range [11,65,103,235]. Drummond's dropseed may be most common in Texas [11,53,187] but has been reported in several states including Louisiana, Mississippi, Alabama, Missouri [187,235], Oklahoma, Kansas [11,235], Iowa, Kentucky, Tennessee, and Georgia [235]. According to Engstrom [65], a reported occurrence of tall dropseed in Maine [184] was actually Drummond's dropseed, although this is well outside its typically described range. Mississippi dropseed apparently has the most restricted distribution [187,235], with reports limited to Texas [53,167,187], Louisana, and specific areas in southwestern Arkansas, southern Mississippi [187,235], and southeastern Missouri [235]. It may occur in other areas of the south-central United States [11,235].
Presettlement FIRE REGIMES in communities where tall dropseed typically occurs are characterized by frequent to occasional surface fires. A review of the tallgrass prairie ecosystem notes that fire-return intervals likely varied greatly, although typical estimates range from 2 to 5 years. Fragmentation of prairies and fire exclusion following European settlement resulted in decreases in fire frequency [215]. In a review, Wright and Bailey [257] note the role of topography: Areas of the Great Plains with level to rolling topography may experience more frequent fire, at about 5- to 10-year intervals, and those in areas with rough topography may experience fire at 15- to 30-year intervals. Large fires were most likely to occur when a period of drought followed a period of above-average precipitation, because these conditions would result in abundant, continuous, and dry fuels [257]. Analysis of burn scars in a cross timbers community with tall dropseed in the Trinity River watershed in Texas found that 16% of the area had not been burned for ≥10 years, 37% of the area had not been burned for 6 to 9 years, 44% had not been burned for 1 to 5 years, and 3% had been burned the preceding year [60]. Tall dropseed occurred on 4 of 18 plots in an Arkansas savanna-glade-woodland that had a 5.7-year fire-return interval [118]. Tall dropseed occurs in west gulf coast plain calcareous prairies in a matrix of calcareous forests in west-central Louisiana. Fire frequency in these prairies is estimated to range from 5 to 20 years [162]. Prescribed burning has increasingly been used to maintain prairie openings of the Mississippi gulf coast plain that are occupied by tall dropseed, with prescribed fire frequency on Forest Service lands in the area increasing from none in the 1960s to an average of 2.9 per prairie per decade in the 1990s. The authors believed this level of burning would maintain prairie openings [253]. See the Fire Regime Table for additional information on FIRE REGIMES of vegetation communities in which tall dropseed is likely to occur. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
In prairies where tall dropseed occurs, natural, lightning-ignited fires typically occur in the growing season while many prescribed fires are conducted in the dormant season [29]. In tallgrass prairies, lightning-ignited fires occurred from March to November but were most common in the mid- to late summer [29]. According to a review, green matter and humidity may have limited the extent of such fires except in periods of drought [215]. April burns likely comprised less than 1% of lightning fires in the northern Great Plains. Burning in the dormant season, a common management practice, likely favors warm-season species more than lightning-ignited fires. Dormant-season fires along with grazing, fragmentation, and fire suppression reduce the likelihood and spread of lightning-ignited summer fires [109].
Fire exclusion may cause encroachment of woody species into communities occupied by tall dropseed. Fire is often used to restrict woody species to riparian zones and protected areas of southern mixed-grass prairie and tallgrass prairie (reviews [215,237]). Comparison of photographs from 1936 to those from the late 1970s, a period of fire exclusion, showed a decline in the area of prairie openings in the Mississippi coastal plains, a community occupied by tall dropseed [253]. In west-central Louisiana tall dropseed was listed as a species of 2 southern calcareous prairie types. In both these types physiognomy is altered by the invasion of eastern redcedar, white ash (Fraxinus americana), and honey-locust (Gleditsia triacanthos) that occurs with fire exclusion [162]. Tall dropseed was listed as a species of limestone glades of the Midwest, which depend on fire or other management to prevent succession to forest [16]. Following 8 years without burning or mowing, a northeastern Texas prairie with scattered patches of tall dropseed was developing into a "semi-woodland" due to encroachment from creek plum (Prunus rivularis) [171]. According to a review focused primarily on composite dropseed, shading associated with establishment of woody species due to fire exclusion threatens shade-intolerant species, including tall dropseed [65]. Overgrazing may result in faster rates of woody invasion than fire exclusion alone [209].
Fuel loads in communities with tall dropseed vary among years, sites, and FIRE REGIMES. The maximum aboveground biomass of 3x3-foot (1x1 m) monocultures of tall dropseed in the Blackland Prairie region of central Texas was over 1,000 g/m² in 2001 and over 500 g/m² in 2002 [255]. Fine fuels in tallgrass prairies are continuous and can occur at loads of 3,000 to 4,000 lb/acre (Owensby personal communication cited by [237]). On a remnant mixed-grass prairie near Hays, Kansas, mulch depth in communities dominated by buffalograss, sideoats grama, and tall dropseed ranged from 0.9 inch (2.2 cm) in October to 1.8 inches (4.5 cm) in July [73]. Litter mass in tallgrass prairie sites with 4-foot (1.2 m) deep loamy soils in south-central Oklahoma ranged from nearly 3,000 to nearly 8,000 kg/ha on unburned sites and ranged from 0 to just over 4,000 kg/ha on sites burned 1 to 3 times. On sites with 2- to 10-inch (5-25 cm) deep loam soils over hard limestone, differences in litter mass on burned (0-4,000 kg/ha) and unburned sites (2,000-4,000 kg/ha) were less distinct, with yearly and treatment effects having a larger impact than burning [64]. Conversions of these fuel densities to kg/ha are provided in the table below for comparison:
Amount of fuel in tallgrass prairies converted to kg/ha for comparison Location Relative abundance of tall dropseed Fuel description kg/ha Tallgrass prairie General, not site specific Fine fuels 3,360 - 4,450 (review by [237]) Bluestem rangeland, Kansas 0.0 to 3.7% relative cover Protective mulch (dry matter) 1,220-3,240 [152] Tallgrass prairie, south-central Oklahoma Late successional species on the site, abundance not provided Litter mass 2,000-8,000 [64] Blackland prairie, Texas 3x3-foot (1x1 m) planted monocultures Aboveground biomass 5,000-10,000 [255]Leaf area ratio and persistence of tall dropseed leaves may influence overall fuel characteristics. Tall dropseed leaves collected from a dune site near Ft. Supply, Oklahoma, had an average biomass of 0.9 g, average leaf area of 8,500 mm², and a leaf area ratio of 9,390 mm²/g [252]. Some leaves within dense tall dropseed bunches may remain green through winter [144,224]. Some leaves may bleach white in the winter [246] and remain on the bleached stems through a 2nd summer [246] or up to a year [188]. Tall dropseed tufts can contain substantial amounts remnant plant material [45]. See Fuel condition for potential impacts of these characteristics on tall dropseed's response to fire.
Tall dropseed may be able to tolerate longer periods without fire in communities in which fuel accumulation occurs comparatively slowly. Tall dropseed occurred at 0.2% basal cover in a shortgrass prairie dominated by buffalograss, blue grama, and western wheatgrass near Hayes, Kansas, that had not been burned or grazed by livestock for 60 years [111]. Midgrasses including tall dropseed occurred on a mixed-grass prairie that had been undisturbed for 15 years but accumulated less mulch than a neighboring undisturbed tallgrass prairie where a 4.5- to 8-inch (11-20 cm) thick mulch layer had developed and tall dropseed did not occur [250]. In the first few years following fire, tall dropseed stem density in the Konza prairie was positively correlated with weight of standing dead herbaceous material on a site with deep soil (P=0.043), but not on a site with shallow soil [54].
Immediate fire effect on plant: As of late 2009, no information was available on the immediate effects of fire on tall dropseed. Tall dropseed may survive and sprout tillers after fire (see Vegetative regeneration). Mississippi dropseed has rhizomes that may survive fire; however, information on morphology and depth of Mississippi dropseed rhizomes is lacking (See Botanical description). Postfire survival of tall dropseed is likely related to the amount and condition of litter accumulated in tufts and the resulting fire severity (see Fuel condition).
Tall dropseed seeds and/or seedlings may be more vulnerable to fire than established plants. Although tall dropseed was ranked fourth in late season ramet emergence in an annually burned prairie, tall dropseed seedlings did not occur on these sites [20]. Tolerance of seedlings to temperatures up to 145 °F (63 °C) was tested in a greenhouse with generally high survival rates that varied with exposure time and seedling age. All 5-week-old seedlings survived 9 hours of exposure to hot wind up to 145 °F, while 64% of 3 week-old seedlings survived 4 hours of exposure to temperatures of 140-153 °F (60-67 °C) [157].
Tall dropseed provides forage of intermediate value and typically of fair palatability for livestock. Tall dropseed may be an important component of the diet of bison [41,240], birds [99,143,166], and small mammals [124], including cottontail rabbits [176]. Tall dropseed comprised 12.5% to 25.9% of the diet of bison on the Konza prairie. Use of tall dropseed by bison [41], scaled quail, and northern bobwhite was greatest in winter. Use by scaled quail [143] and northern bobwhite [99,143] has been shown to vary with plant community [99] and occurrence of fire [77,96,143,240] (See Interactions between fire and grazing). Tall dropseed has been described as having poor forage value for wildlife [224], particularly deer [236], and was used little by grasshoppers in tallgrass pastures near Manhattan, Kansas [129]. Tall dropseed has low values of many important nutrients, which may vary with season and site factors. However, Crawford and others [44] and Johnson and Nichols [120] describe tall dropseed's forage value as fair to good.
Palatability: Palatability of tall dropseed is generally fair [166,222,224] or moderate [44]. It is most palatable early in the growing season [44,156,224] and before reaching maturity [44,224]. It was considered a "secondary forage species" for cattle, sheep, and goats [236]. In the western cross timbers of Texas it was moderately grazed in mid-March, April, and December and lightly grazed in early March, late August, and September [60]. However, it was not selected on sites in eastern Texas [127] or southeastern Nebraska [156]. Palatability may vary among tall dropseed varieties [60,144].
Nutritional content: Tall dropseed provides a fair to good source of some nutrients, while lacking others. Protein has been shown to comprise about 4% to nearly 13% of tall dropseed vegetation [24,76,114,176], while tall dropseed seeds and hulls contained 25.11% protein in a Pinchot's juniper-dominated rangeland in northwestern Texas [143]. Tall dropseed vegetation in northwestern Texas with average protein content of 6.08% was considered a deficient to fair source of protein [76]. Tall dropseed digestibility in tallgrass prairie southwest of Stillwater, Oklahoma, ranged from 38.5% to 68.7% [24], and percentage of digestible organic matter averaged 48% in tall dropseed on the Edwards Plateau in Texas [114]. Water content of tall dropseed ranged from 31% to 66% near Stillwater, Oklahoma [24], and averaged 55% in tall dropseed from the Edwards Plateau. Phosphorus comprised 0.16% of tall dropseed from the Edward Plateau [114], and percent phosphoric acid ranged from 0.12% to 0.26% in tall dropseed from northwestern Texas. Tall dropseed from this area was considered deficient to very deficient in phosphoric acid but a fair to good source of calcium oxide [76]. Fat comprised 1.9% of the dry weight of tall dropseed in an upland hardwood forest-tallgrass prairie of central Oklahoma [176]. Lipid content of tall dropseed seeds and hulls averaged 3.7% [143].
Season and site factors may influence tall dropseed nutritional value. Tall dropseed exhibited greater protein content [24,176], digestibility, and water content early in the growing season than later in the growing season [24]. Vegetation on 4-year-old and 8-year-old burn sites in Pinchot's juniper-dominated rangelands with tall dropseed provided better quality scale quail and northern bobwhite diets than unburned areas [143]. Crude protein, water content, and digestibility were generally greater in burned and herbicide treated areas of Oklahoma tallgrass prairie with tall dropseed than untreated areas [24]. In an upland forest-tallgrass prairie of central Oklahoma, tall dropseed in undisturbed areas had higher content of certain amino acids than areas subject to removal of woody species using herbicides and burning [176].
Cover value: Tall dropseed may provide cover for small mammals and ground nesting birds. Densities of various groups of grasshoppers in a tallgrass prairie with tall dropseed are provided by Craig and others [42].
Communities with tall dropseed provide cover for some small mammals. Hispid cotton rat, deer mouse, and western harvest mouse occurred at densities greater than 4.0 individuals/acre in at least one season in a buffalograss-sideoats grama-tall dropseed community near Hays, Kansas. Prairie voles selected areas of this community with dense cover [73]. In 1966 these same species occurred at densities above 2.0 individuals/trapline in a mixed-grass prairie in north-central Kansas where tall dropseed was common [125]. In a mixed-grass prairie of Ellis County, Kansas, hispid cotton rats were trapped more often than expected in all seasons based on trapping effort in vegetation dominated by buffalograss, sideoats grama, and tall dropseed and in winter and spring on another site dominated by the same species [74]. In this area, deer mouse and western harvest mouse were not significantly associated with tall dropseed in remnant prairie [221].
Ground-nesting birds that use prairies with tall dropseed include prairie chickens and quail. Tall dropseed was a dominant species in 2 communities used by greater prairie chickens in Kansas, one that was preferred in all seasons and another that was preferred in summer [190]. Greater prairie chickens used tallgrass prairies with a small component of tall dropseed more than mid- and shortgrass prairies with substantial proportions of tall dropseed. Lesser prairie chickens used limited areas of the shortgrass prairies [122]. Increases in tall dropseed where it is scarce could potentially improve the quality of quail habitat in western Oklahoma. Tall dropseed generally has fair value for nesting habitat and low value for protective cover [166].
The scientific name of tall dropseed is Sporobolus compositus (Poir.) Merr. (Poaceae).
Three varieties of this species are recognized [11,123,235]. In the few instances in which
unambiguous information regarding variety is available, this review refers to varieties by
the following common names:
Sporobolus compositus var. clandestinus is not included in this review because it is considered a separate species, S. clandestinus (Biehler) A.S. Hitchc. [11,123,147,235].
Sporobolus compositus, the composite dropseed[2] or tall dropseed, is a native North American prairie grass growing from two to four feet tall. Also called rough dropseed and meadow dropseed, it is common on the Great Plains, and found in most states in the United States.
It flowers from August to September. The name derives from the readily falling grain. Dropseed has little value as food; its palatability decreases with its age.
Sporobolus compositus, the composite dropseed or tall dropseed, is a native North American prairie grass growing from two to four feet tall. Also called rough dropseed and meadow dropseed, it is common on the Great Plains, and found in most states in the United States.
It flowers from August to September. The name derives from the readily falling grain. Dropseed has little value as food; its palatability decreases with its age.
