Changes in surface injuries and mortality rates of Saguaro (Carnegiea gigantea) cacti over a twelve-year period

injuries and the mortality rate of a population of 253 saguaro cacti were determined over a twelve-year period of study. Seventeen percent of the saguaro population had few surface injuries throughout the period. Thirty percent of the population showed a marked increase (more than half of the cacti in this group showed a mean increase in barking of 80%) in scaling and barking injuries over the 12-year period. Twenty-six percent of all cacti had more than 90% scaling and barking on stem surfaces throughout the period. Rates of scaling and barking injuries (morbidity) are high considering the long life span of saguaros. Finally, 27.3% of the saguaro population died over the twelve-year period. Twenty-five percent of the cacti that died over the period exhibited few surface injuries in 1990 while 65% of the cacti that died over the period had 98% scaling and barking on stem crests in 1990. A mortality rate of 27% over 12 years (2.3% annually) is very high considering these cacti may live for long time periods.