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Eve Brantley, Jennifer Mitchell, and B. Graeme Lockaby Auburn University School of Forestry

Influence of Chinese privet ( Ligustrum sinense Lour.) on floodplain productivity and regeneration. Eve Brantley, Jennifer Mitchell, and B. Graeme Lockaby Auburn University School of Forestry and Wildlife Sciences Center for Forest Sustainability. Ligustrum sinense Lour.

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Eve Brantley, Jennifer Mitchell, and B. Graeme Lockaby Auburn University School of Forestry

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  1. Influence of Chinese privet (Ligustrum sinense Lour.) on floodplain productivity and regeneration Eve Brantley, Jennifer Mitchell, and B. Graeme Lockaby Auburn University School of Forestry and Wildlife Sciences Center for Forest Sustainability

  2. Ligustrum sinense Lour. • Often forms dense thickets, particularly in bottomland forests and along fencerows • Shade and flood tolerant • Aggressive colonizer - spreads locally by root sprouts and widely by abundant bird- and other animal-dispersed seeds. • Present in all of the southeastern states and ranges north to Massachusetts Invasive Plants of the Eastern United States

  3. Objectives • To determine how increasing densities of Chinese privet influence aboveground and belowground net primary productivity. • Investigate influence of Chinese privet density on native plant regeneration

  4. LaGrange GA Georgia, USA Columbus GA Study Sites • 16 - 0.04 ha study sites selected in West Georgia • Southern Piedmont • Floodplains occupied by deciduous forests, closed canopy

  5. Study Sites • Sites represent a continuum of understory Chinese privet stem density (0 – 100%) Study sites

  6. To determine how increasing densities of Chinese privet influence above- and belowground net primary productivity. Aboveground productivity: • Monthly collection of litterfall (3 -.25 m2 traps per site) • Litterfall samples dried, weighed and analyzed for C, N, P • Diameter at breast height (DBH) recorded annually for all stems greater than 10 cm DBH and used to estimate stem annual increment

  7. To determine how increasing densities of Chinese privet influence above- and belowground net primary productivity. Belowground productivity: • Two fine root samples collected every 6-8 weeks using soil core method (Vogt and Persson 1991, Anderson and Ingram 1993, Bledsoe et al. 1999) • Samples collected to a depth of 11 cm and sorted size classes by live and dead fractions • Samples dried, weighed and analyzed for C and N

  8. Investigate influence of Chinese privet density on native plant regeneration Regeneration: • 12 – 1 m2 plots established at 3, 6 and 9M from site center on north, south, east, and west ordination • After spring leaf out, vegetation in each regen plot less than 10 cm DBH will be identified to species and its height recorded

  9. Statistics • SAS version 9.1 • Linear and non-linear regression • All differences below p < 0.10 reported

  10. Year 1 Results Increasing privet understory

  11. Year 1 Results • Chinese privet presence measured by proportion of understory - percent of understory that is Chinese privet (0 – 100%) • Curvilinear and linear relationships between Net Primary Productivity and privet invasion • Strong, negative relationship between Chinese privet invasion and native plant regneration

  12. Net Primary Productivity and Chinese privet understory proportion Significant curvilinear relationship between • Total NPP & proportion of understory as privet (P < 0.008 R2 .5821)

  13. Net Primary Productivity and Chinese privet understory proportion Significant curvilinear relationship between • Aboveground NPP & proportion of understory as privet (P < 0.05 R2 .4133)

  14. Net Primary Productivity and Chinese privet understory proportion Significant nonlinear relationship between • Belowground NPP & proportion of understory as privet (P < 0.01 R2 .5311)

  15. Regeneration % Chinese Privet Understory (2004) compared with % Chinese Privet in Regeneration Layer (2005) y = 0.9688x + 5.9086 (p < 0.001 R2 = 0.933)

  16. Regeneration % Chinese Privet Understory (2004) compared with % Native Species in Regeneration Layer (2005) y = -0.9641x + 94.115 (p < 0.001 R2 = 0.9472)

  17. Year 1 Conclusions - NPP • In southeastern Piedmont riparian areas Chinese privet appears to influence • Net Primary Productivity • Native species regeneration

  18. As Chinese privet stem densities rise: • ANPP is the greatest at medium levels of Chinese privet understory proportion (40-80%) • ANPP is lower at the low (0-40%) and high (80-100%) levels of Chinese privet understory proportion

  19. As Chinese privet stem densities rise: • BNPP is the greatest at medium levels of Chinese privet understory proportion (40-80%) • BNPP is lower at the low (0-40%) and high (80-100%) levels of Chinese privet understory proportion

  20. Year 1 Conclusions – Regeneration • Proportion of Chinese privet in the understory is strongly related to the regeneration layer • Increase in Chinese privet regeneration with increasing proportion of understory Chinese privet • Decrease in native species regneration with increasing proportion of understory Chinese privet ~ 50% understory privet, native regen drops below 40%

  21. Dr. B. Graeme Lockaby Dr. Kathryn Flynn Dr. William Conner Dr. James E. Hairston Jennifer Mitchell Don Vestal Robin Governo Lena Polyakova Rachel Jolley Jackie Crim Emile Elias Acknowledgements Auburn University School of Forestry and Wildlife Sciences, Center for Forest Sustainability

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