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Examining the mechanistic pathways of interactions between shrubs and annual plants in semi-arid and arid ecosystems

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March 6th Progress report for Alex Filazzola @ York University

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Examining the mechanistic pathways of interactions between shrubs and annual plants in semi-arid and arid ecosystems

  1. 1. EXAMINING THE MECHANISTIC PATHWAYS OF INTERACTIONS BETWEEN SHRUBS AND ANNUAL PLANTS IN SEMI-ARID AND ARID ECOSYSTEMS. Alessandro Filazzola PhD Candidate Progress Report – March 6th
  2. 2. Positive plant-interactions
  3. 3. Multiple mechanisms Filazzola & Lortie 2014
  4. 4. Multiple mechanisms More than one dominant mechanism may operate at a time Smit et al. 2009 No herbivores With herbivores
  5. 5. Climate determines plant-interactions Callaway et al. 2002
  6. 6. Dominant-mediated distribution Survival of experimentally planted seedlings of Taraxacum officinale within and outside Azorella monantha cushions at 3200 m a.s.l. Cavieres et al. 2007
  7. 7. Purpose To examine or decouple the different mechanistic pathways and drivers of plant-plant interactions in arid systems
  8. 8. Chpt Title Progress 1 A systematic review and conceptual framework for the mechanistic pathways of nurse plants Published in GEB, Summer 2014 2 Contrasting effects of drought-stress and consumer pressure on plant-plant interactions in an arid shrub-understory system Submit to Ecology 3 The effect of a dominant shrub on annuals plants in a desert system changes along a gradient of continentality. Active – repeat census in March 2015 4 Shrubs directly and indirectly increase seed densities under canopy in arid environments Data collection complete 5 Shrubs expand the species distributions of annual plants in arid environments Begin survey – April 2015
  9. 9. Chapter 3 Purpose: To determine how desert shrubs influence annual plant productivity along a regional gradient of climate. H: The magnitude and frequency of positive interactions between shrubs and annuals will be greatest at intermediate levels of stress along a regional gradient of continentality. C3
  10. 10. C3
  11. 11. C3Ephedra californica Shrub Amsinckia tessellata Annual
  12. 12. C3 x 20
  13. 13. 0 100 200 300 400 10 12 14 16 18 20 22 0 1 2 3 4 5 Precipitation(mm) Temperature(C) Gradient point C3 Worldclim data: mean 1950-2000
  14. 14. 0 100 200 300 400 14 15 16 17 18 19 0 1 2 3 4 5 Precipitation(mm) Temperature(C) Gradient Point ClimateWNA – 2007-2012 C3
  15. 15. 0 5 10 15 20 25 0 1 2 3 4 5 AridityIndex Gradient Point ClimateWNA – 2007-2012
  16. 16. Chapter 5 Purpose: To examine the role of shrubs in expanding the range of annual plants. H: Shrubs may be able to expand the realized niche of an annual species beyond their distribution by reducing the abiotic stresses that would otherwise limit their establishment. C5
  17. 17. Kelbaker road gradient C5 Elevation Elevation
  18. 18. Kelbaker road gradient C5
  19. 19. C5Relative Humidity (%) Temperature (C◦)
  20. 20. C5Relative Humidity (%) Temperature (C◦)
  21. 21. C5 x 20x 20x 20x 20x 20 Relative Humidity (%) Temperature (C◦)
  22. 22. ? ? C5
  23. 23. USDM - March 2015 C5
  24. 24. Future work Chpt Title Goals 3 The effect of a dominant shrub on annuals plants in a desert system changes along a gradient of continentality. Conclude census in March-April 2015 Data inputted June 2015 4 Shrubs directly and indirectly increase seed densities under canopy in arid environments Conduct statistical analysis & write-up Fall 2015 5 Shrubs expand the species distributions of annual plants in arid environments Begin survey – April 2015 Field manipulations – Jan 2016
  25. 25. Thank you!

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