GEOG5839.17, Dendroecology

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GEOG5839.17, Dendroecology

  1. 1. November 6 DendroecologySource: Whitney Crawford
  2. 2. Dendroecology is the use of tree-ring dating and analysesto investigate events and processes involvingthe interactions of organisms with their environment.
  3. 3. Source: William Ciesla
  4. 4. Western spruce budworm Choristoneura occidentalis Freeman
  5. 5. Wind-thrown red pine Quetico Provincial Park, Canada
  6. 6. ASSIGNED READINGTom Swetnam and Peter Brown (2010), Climatic inferencesfrom dendroecological reconstructions. M.K. Hughes et al.(eds.), Dendroclimatology, Developments inPaleoenvironmental Research.
  7. 7. Why does Ecologyneed dendroecology?
  8. 8. “ Many ecosystem processes, especially those affected by climate changes, manifest themselves only over longer time periods and broader spatial scales than ” encompassed in typical ecological studies. Tom Swetnam and Peter Brown Dendroclimatology, 2010
  9. 9. “ Understanding the dynamics of long-lived organisms and ecosystems — and the role of climate in controlling these dynamics — ” requires decadal to centennial and landscape- to regional-scale perspectives. Tom Swetnam and Peter Brown Dendroclimatology, 2010
  10. 10. DENDROECOLOGY Forest demography Growth dynamics Disturbance ecology
  11. 11. THE PRINCIPLE OF AGGREGATE TREE GROWTHRt = At + Ct + δD1t + δD2t + Et
  12. 12. Forest demography
  13. 13. Source: Dawn Hopkins Source: Kurt Kipfmueller
  14. 14. “ Ecologists have long recognized that time series of tree births and deaths are of fundamental value for understanding forest and woodland dynamics. ” Tom Swetnam and Peter Brown Dendroclimatology, 2010
  15. 15. Source: Kurt Kipfmueller
  16. 16. 1500 1600 1700 1800 1900 2000
  17. 17. Tree recruitment dates (by 50-year periods) 1500 1600 1700 1800 1900 2000
  18. 18. Tree mortality dates (by 50-year periods) 1500 1600 1700 1800 1900 2000
  19. 19. Pinyon Demography at Sevilleta LTER, Central New MexicoSource: Betancourt et al. (2004)
  20. 20. Sampling dead trees in the pinon-juniper woodlands Tom Swetnam
  21. 21. COMPLICATING FACTORS
  22. 22. The condition of dead trees affects the continuity of their record.Photograph: John Krumm
  23. 23. Snags may have lost an unknown number of outer rings.
  24. 24. TREE DOES NOT DATE OF EQUAL GERMINATIONRECRUITMENT
  25. 25. Hi ing the pith is easy when you collect an entire cross-section.
  26. 26. It’s more difficult when coring, especially if growth is asymmetric.
  27. 27. Coring height Root collarHow many years separate the root collar from the stem at coring height?
  28. 28. The germination date can be MUCH earlier than tree age at coring height.Source: Gutsell and Johnston (2002)
  29. 29. Source: Kurt Kipfmueller Germination doesn’t happen immediately a er disturbance.
  30. 30. The ecesis interval is the amount of time betweenan initial disturbance and the successful establishmentof the first trees.
  31. 31. THE ‘FADING RECORD’ PROBLEMThe preservation of dead trees becomes less common with timebefore present, and obtaining estimates of past mortality eventsdepends both on persistence of woody material and the ability toadequately sample the material to obtain death dates.
  32. 32. How can we reduce the effectsof these different sources of uncertainty?
  33. 33. “ In old, uneven-aged forests, sometimes hundreds of trees must be sampled to obtain adequate characterization of age structure distributions. ” Tom Swetnam and Peter Brown Dendroclimatology, 2010
  34. 34. Source: Dawn Hopkins Source: Kurt Kipfmueller
  35. 35. Source: Swetnam and Brown (2010) Germination pulses of ponderosa pine have coincided with warm, wet summers.
  36. 36. Growth dynamicsSource: Kyle Pierce
  37. 37. Growth releases may be caused by the death of ‘overstory’ trees.
  38. 38. A growth release is the opposite of a suppression,with growth increasing rapidly for several years.
  39. 39. A growth suppression is a rapid reduction of growthfrom one year to the next, usually lasting for several years.
  40. 40. Source: Fri s and Swetnam, 1989 Growth release caused by 1966 timber harvest.
  41. 41. Source: Eli Sagor Growth suppressions are caused commonly by defoliating insects.
  42. 42. Source: Fri s and Swetnam, 1989 Suppression, possibly caused by A.D. 1064 eruption at Sunset Crater in Arizona.
  43. 43. Source: Berg et al. (2006) Release events can be used to identify past insect outbreaks.
  44. 44. Source: Berg et al. (2006) You really need to study the frequency of releases across MANY stands.
  45. 45. Disturbance ecologySource: Miguel Vieira
  46. 46. THE PRINCIPLE OF AGGREGATE TREE GROWTHRt = At + Ct + δD1t + δD2t + Et
  47. 47. Western spruce budworm Choristoneura occidentalis Freeman
  48. 48. Source: brewbooks White fir Abies concolor
  49. 49. Douglas-fir Pseudotsuga menziesii
  50. 50. Source: William Ciesla
  51. 51. Source: William Ciesla
  52. 52. “ No typical pa ern or trend in western spruce budworm epidemics has been apparent; most of the early epidemics lasted for a few years and ” then subsided naturally; others persisted longer, at times without spreading over large areas. David Fellin and Jerald Dewey Western Spruce Budworm, 1982
  53. 53. Source: Dave Powell
  54. 54. HOST NON-hOST
  55. 55. “ The tree-ring basis for developing outbreak chronologies is the observation of very sharply reduced ring growth in the host species during ” the defoliation episode, which typically lasts for a decade or longer. Tom Swetnam and Peter Brown Dendroclimatology, 2010
  56. 56. Western spruce budworm Choristoneura occidentalis Freeman
  57. 57. Source: Brewbooks
  58. 58. HOST NON-hOST White fir Ponderosa PineDouglas-fir
  59. 59. Source: Tom Swetnam Growth suppression in white fir defoliated by spruce budworm
  60. 60. THE PRINCIPLE OF AGGREGATE TREE GROWTHRt = At + Ct + δD1t + δD2t + Et
  61. 61. G(HOST) < G(NON-HOST) = potential outbreak
  62. 62. Source: Ryerson et al. (2003)
  63. 63. Comparisons between hosts and non-hosts can help identify budworm outbreaks BLACK = Host < Non-host GRAY = Host > Non-hostSource: Ryerson et al. (2003)
  64. 64. Percentage of trees recording an outbreak of western spruce budworm in the Rio Grande National Forest, ColoradoSource: Ryerson et al. (2003)
  65. 65. “ In old, uneven-aged forests, sometimes hundreds of trees must be sampled to obtain adequate characterization of age structure distributions. ” Tom Swetnam and Peter Brown Dendroclimatology, 2010
  66. 66. Do drought conditions inhibit spruce budworm outbreaks?Source: Ryerson et al. (2003)
  67. 67. November 6 DendroecologySource: Whitney Crawford
  68. 68. Strengths of dendroecology1. Tree-ring records provide a much longer perspective than documentary records or modern surveys.2. Tree-ring evidence has a high degree of temporal precision compared to other paleoecological tools.3. Chronological control allows multiple lines of evidence to be compared.
  69. 69. Limitations of dendroecology1. Tree-ring records are fragmentary and can be distributed irregularly in time and space.2. Some species, events or processes cannot be reconstructed and therefore remain unknown.3. Past ecological conditions may have no analog in the modern system, making their behavior difficult to interpret.
  70. 70. GEOG8280 XT C L AS SNE

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