Predicting morbidity and mortality ofCarnegiea gigantea1

Abstract

Abstract Research has shown that older plants of more than 20 species of tall, long-lived cacti of the Americas have surface bark injuries. This bark is caused by sunlight exposures over several decades. This bark formation (which first appears on south-facing surfaces) leads to premature morbidity and eventually premature mortality (rates of 2.3% per year for Carnegiea gigantea. Current research was aimed at changes in C. gigantea bark formation over a 4-yr period. Of the 89 C. gigantea analyzed, 35% died. Among survivors, surface areas with bark increased by 20% over the 4-yr period. Rib troughs of a more southerly orientation had more bark injuries (up to 15% more) than troughs with a more northerly orientation. Over time, the amount of bark on north-facing troughs becomes similar to bark levels on south-facing troughs. Machine learning techniques that used 18 parameters of bark percentages on cactus surfaces had an 84% probability of predicting cactus death with two independent methods. Machine learni...