Aristida stricta

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Aristida stricta
Aris stri.jpg
Photo by John R. Gwaltney, Southeastern Flora.com
Scientific classification
Kingdom: Plantae
Division: Tracheophyta - Vascular plants
Class: Lilianae - Monoctyledons
Order: Poales
Family: Poaceae
Genus: Aristida
Species: A. stricta
Binomial name
Aristida stricta
L.
ARIS STRI 2 dist.jpg
Natural range of Aristida stricta from USDA NRCS Plants Database.

Common names: Threeawn, Wiregrass

Taxonomic notes

Synonyms: A. beyrichiana Trin. & Rupr.; A. stricta var. stricta Michx.

Description

A. stricta is a cespitose (growing in dense clumps or mats) perennial bunch grass ranging in size up to 15 cm across at the base.[1] The blades are narrow, flat, involuted, and appear to be round like wire.[1] The leaves are rigid yet bendable and generally 0.5m long.[1] There are 2-3 leaves in each tiller.[2] The shallow, dense, wiry roots are adept at taking in nutrients.[1] It maintains an approximate density of five clumps per square meter.[1] The seeds are translucent brown, rough in texture, cylindrical like in shape but narrow at the ends, 4.5 mm in length and 0.4 mm in width.[1] With the correct fire pattern a population of A. stricta can survive indefinitely, possibly germinating from seeds thousands of years ago,[1] although they can be killed by unusually severe fires.[3] Growth and reproduction of A. stricta can be influenced by surrounding groundcover and longleaf pines.[4] The closer A. stricta is to near by long leaf pines, the greater their potential reproductive output and biomass.[4]

Distribution

A. stricta is found in areas adjacent to the Coastal Plain, in the Piedmont areas in northeast North Carolina to northeast South Carolina.[5]

Ecology

Due to the loss of habitat A. stricta used to be the keystone species of the Coastal Plain in the Carolinas.[5] The foliage of A. stricta helps the lightning-set fires to spread and thereby maintain the habitats, pine savannas, sandhills, and pine flatwoods. [5] Although, those habitats are not common due to agriculture, pine farms, and development. [5] Fire suppression and ground (soil) disturbance has led to a rapid decline in A. stricta’s population throughout the Coastal Plain. [5] Weakley mentions Ward (2001) proposes there is varietal status for A. stricta and A. beyrichiana, see Weakley’s most recently updated guide. Wunderlin and Hansen (2011) mention that the Aristida stricta, in Florida, is var. beyrichiana. [6]

Habitat

Aristida stricta is considered a native groundcover in upland pinelands of South Georgia. [7] It is present in sand that is not fertile. [1]

Phenology

Flowers spring to fall. [6] Flowering may be induced by disturbances including transplanting, growing close to ploughed firelines, cut by track-laying vehicles, or defoliation (removal of leaves), but not defoliation alone. [2] The highest amount of inflorescence has been observed to occur in August and September following a May burn and after growing season fires verses dormant season fires. [2] [8]

Seed dispersal

Aristida stricta disperses by gravity.[9]

Seed bank and germination

Seed viability falls out between 212–248˚F. [2] Typically seed viability can last up to four months. [10] Short-term seed persistence can occur in the soil. [11] Requires high temperature for germination (86–95˚F). [12] Successful germination occurs when seeds are buried less than 2 cm. [10] Following fire, seeds that are year old may germinate right away, whereas those four months old could take another hundred days to germinate. [2] Dry seed has a higher tolerance of heat than moist seed.[2] Summer burning triggers effective reproduction. [1] The month of burn appears to affect the abundance of reproductive tiller (growth unit that gives rise to a stem, seedhead, roots, and leaves), [13] with May having the highest amount.[2] One study found that seedlings only occurred when the area was burned in the lightning season. [10] Germination rate and seedling count are highest in July and May. [14]

Fire ecology

A. stricta is very flammable because of its highly fibrous leaf structure, vast amount of leaves, and duration of dead leaves which do not detach quickly. [1] A. stricta can withstand fire suppression for 20 or 40 years. [1] However, because the sexual reproduction of A. stricta relies on growing season fires, years of human fire suppression has diminished the population. [15] After burning there is a heavy grazing period but during this time A. stricta is unappealing to grazers. [2] A. stricta grows up to 1 in per day following fire. [2] Light intensity fires cause production of more culms (stems) per clump of A. stricta. [8] The spatial variation of fire intensity may have a high impact on A. stricta recruitment patterns. [8]

Conservation and management

A. stricta has been observed to be negatively affected by disturbance. [16] [17] A. stricta has also been observed to have a strong association with agriculture history and burning frequency. [18] It has been observed to respond positively to cross chopping combined with ground rock phosphate fertilization. [19] A. stricta has lowest mortality when hexazinone (a herbicide) is used during dry times and when chopping is performed with high soil moisture. [20] Aboveground damage to clones can be healed but serious root damage commonly leads to death. [20]

Cultivation and restoration

A. stricta is important in longleaf ecosystem restoration because of the critical role it serves by increasing water holding capacity, improving soil structure, and providing a fuel source for fire. [4] [21] [22]

Photo Gallery

References and notes

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Clewell, A. F. (1989). Natural History of Wiregrass (Aristida stricta Michx., Gramineae). Natural Areas Journal 9: 223-233.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Parrott, R. T. (1967). A study of wiregrass (Aristida stricta Mitchx.) with particular reference to fire, MA Thesis, Duke University: 137.
  3. Robertson, Kevin M. 2015. Unpublished data from the Pebble Hill Fire Plots (Pebble Hill Plantation, near Thomasville, Georgia) indicating death of some genetic individuals of A. stricta after a prescribed burn in June after five years without fire.
  4. 4.0 4.1 4.2 Wallett, W. D. (2015). Neighborhood interactions of an understory dominant, Aristida stricta, along a soil resource gradient of the long leaf pine ecosystem. Biological Sciences Murray, Murray State University Master of Science 74.
  5. 5.0 5.1 5.2 5.3 5.4 Weakley, Alan S. Flora of the Southern and Mid-Atlantic States: Working Draft of 21 May 2015. University of North Carolina Herbarium (NCU). PDF. 358; 360.
  6. 6.0 6.1 Wunderlin, Richard P. and Bruce F. Hansen. Guide to the Vascular Plants of Florida. Third edition. 2011. University Press of Florida: Gainesville/Tallahassee/Tampa/Boca Raton/Pensacola/Orlando/Miami/Jacksonville/Ft. Myers. 178. Print.
  7. Ostertag, T.E., and K.M. Robertson. 2007. A comparison of native versus old-field vegetation in upland pinelands managed with frequent fire, South Georgia, USA. Pages 109–120 in R.E. Masters and K.E.M. Galley (eds.). Proceedings of the 23rd Tall Timbers Fire Ecology Conference: Fire in Grassland and Shrubland Ecosystems.
  8. 8.0 8.1 8.2 Jeff S. Glitzenstein, D. R. S., William J. Platt (1995). Evaluating the effects of season burn on vegetation in longleaf pine savannas Tallahassee, Florida Game and Fresh Water Fish Comission.
  9. Kay Kirkman, unpublished data, 2015.
  10. 10.0 10.1 10.2 McGee, A. J. (1997). Seed ecology of bunchgrasses of longleaf pine - wiregrass communities at Fort Stewart, Georgia. Biology. Statesboro, Georgia Southern University. Master of Science: 85.
  11. Coffey, K. L. and L. K. Kirkman (2006). "Seed germination strategies of species with restoration potential in a fire-maintained pine savanna." Natural Areas Journal 26: 289-299.
  12. Andreu, M. G., C. W. Hedman, et al. 2009. "Can managers bank on seed banks when restoring Pinus taeda L. plantations in Southwest Georgia?" Restoration Ecology. Vol 17. pgs 586-596.
  13. Trlica, M. J. (1999). "Grass Growth and Response to Grazing ". from http://extension.colostate.edu/topic-areas/natural-resources/grass-growth-and-response-to-grazing-6-108/.
  14. Eerden, B. P. V. (1997). Studies on the reproductive biology of wiregrass (Aristida stricta Michaux) in the Carolina sandhills. Athens, University of Georgia. Master of Science: 89.
  15. Jennifer M. Fill, et al. (2012). The reproductive response of an endemic bunchgrass indicates historical timing of a keystone process. Ecosphere 3: 1-12.
  16. Hebb, E. A. (1971). Site preparation decreases game food plants in Florida sandhills. Journal of Wildlife Management 35: 155-162.
  17. Kirkman, L. K., K. L. Coffey, et al. (2004). "Ground cover recovery patterns and life-history traits: implications for restoration obstacles and opportunities in a species-rich savanna." Journal of Ecology 92(3): 409-421.
  18. C. W. Hedman, S. L. G., and S.E. King (2000). Vegetation composition and structure of southern coastal plain pine forests: an ecological comparison. Forest Ecology and Management 134: 233-247.
  19. Lewis, C. E. (1970). Responses to chopping and rock phosphate on south Florida ranges. Journal of Range Management 23: 276-282.
  20. 20.0 20.1 Outcalt, K. W. (1992). "Factors affecting wiregrass (Aristida stricta Michx.) cover on uncut and site prepared sandhills areas in Central Florida. Ecological Engineering 1: 245-251.
  21. Outcalt, K. W. (1992). "Factors affecting wiregrass ( Aristida stricta Michx.) cover on uncut and site prepared sandhills areas in Central Florida " Ecological Engineering 1: 245-251
  22. Clewell, A. F. (1989). "Natural History of Wiregrass (Aristida stricta Michx., Gramineae)." Natural Areas Journal 9: 223-233.