Potential stressors leading to seedling mortality in the endemic Hayun lagu tree (Serianthes nelsonii Merr.) in the island of Guam

Potential agents of seedling mortality for Guam's only known Serianthes nelsonii (Hayun lagu) tree were determined from the in situ crop of emerging seedlings. We used insecticides to mitigate exotic arthropod pressure, fertilizer to mitigate nutrient deficiency, fungicide to mitigate root pathogen pressure, and supplemental lighting to mitigate low light stress. The fungicide treatment was the only treatment that elicited a substantial increase in seedling longevity. Past reports based on general observations point to insect and ungulate herbivory as likely agents of seedling mortality. Our results identify root pathogens as an additional cause of mortality at the study site. Results may be useful for designing more complex experiments to improve species recovery efforts.