American chestnut (Castanea dentata) COSEWIC assessment and status report: Appendix
Appendix: Comparison of Reproductive and Blighted Individuals Over Three Time Periods
A) Incidence of Flowering/Fruiting; Number of Individuals Reproductive (F) or Non-reproductive (NF), with Percentages Shown in the Diagram
| Survey | Tree dbh (cm) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0-9 | 10-19 | 20-29 | 30-39 | 40-49 | 50+ | |||||||
| NF | F | NF | F | NF | F | NF | F | NF | F | NF | F | |
| 1986 | 383 | 2 | 11 | 12 | 5 | 17 | 0 | 16 | 0 | 4 | 0 | 5 |
| 1997 | 153 | 2 | 36 | 16 | 15 | 12 | 6 | 26 | 5 | 6 | 4 | 6 |
| 2003 | 182 | 10 | 76 | 24 | 18 | 18 | 4 | 21 | 3 | 4 | 1 | 8 |
Figure 1: Percentage of Reproductive Trees by Size Class
* Indicates significant differences among the three surveys.
B) Incidence of Blight; Number of Individuals with Blight (B) or No Blight (NB) Symptoms, with Percentages Shown in the Diagram
| Survey | Tree dbh (cm) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0-9 | 10-19 | 20-29 | 30-39 | 40-49 | 50+ | |||||||
| NB | B | NB | B | NB | B | NB | B | NB | B | NB | B | |
| 1986 | 350 | 32 | 17 | 7 | 14 | 8 | 11 | 4 | 3 | 2 | 4 | 1 |
| 1997 | 73 | 82 | 39 | 13 | 15 | 12 | 18 | 14 | 8 | 3 | 8 | 2 |
| 2003 | 130 | 47 | 67 | 39 | 17 | 20 | 15 | 9 | 0 | 8 | 6 | 3 |
Figure 2: Percentage of Blighted Trees by Size Class
* Indicates significant differences among the three surveys.
Brian Husband analysed the data of the three surveys referenced in the report and prepared the above charts. All statistics were based on Chi-square Contingency Analysis, which determines whether the frequency of trees with and without flowering or blight differs among the three surveys.
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