Crown dieback in ash trees

This dataset comes from a study of symptoms of crown dieback, cankers and symptoms caused by other pathogens and pests in ash trees (Fraxinus excelsior). In all 454 trees were observed in two plots. There are 8 categorical variables, 6 of which are binary and two are trichotomous with values representing increasing severity of symptoms, and one continuous variable, tree diameter at breast height (DBH).

data(ashtrees)

Format

A data frame with 454 observations on the following 9 variables.

plot

a factor with levels 2 6

dieback

a factor with levels 0 1 2

dead50

a factor with levels 0 0.5 1

bushy

a factor with levels 0 1

canker

a factor with levels BRNCH MAIN NONE

wilt

a factor with levels 0 1

roses

a factor with levels 0 1

discolour

a factor with levels 0 1

dbh

a numeric vector

References

Skovgaard JP, Thomsen IM, Skovgaard IM and Martinussen T (2009). Associations among symptoms of dieback in even-aged stands of ash (Fraxinus excelsior L.). Forest Pathology.

Examples

data(ashtrees)
head(ashtrees)
#>    plot dieback dead50 bushy canker wilt roses discolour dbh
#> 1     2       1      0     0   NONE    0     0         0  48
#> 2     2       2      0     1   MAIN    0     0         0  74
#> 3     2       2      0     1   MAIN    0     0         0  71
#> 14    2       2      0     1  BRNCH    0     0         0  76
#> 23    2       0      0     0   NONE    0     0         0  91
#> 24    2       1      1     0   MAIN    0     0         0  82