REPRODUCTIVE ECOLOGY OF MAGNOLIA-SCHIEDEANA (MAGNOLIACEAE), A THREATENED CLOUD FOREST TREE SPECIES IN VERACRUZ, MEXICO

Flowering among three study populations of Magnolia schiedeana Schlecht. (Magnoliaceae) varied considerably, beginning in January or February and continuing for 2 to 4 months. The variability in time of flowering led to very low fruit production in some populations when not coincident with pollinator emergence. Flowers produced a strong fruity fragrance, were functional for one day, protogynous (opening in the morning and becoming male the same afternoon), and self-compatible. Pollinators were beetles, Stenagria sp. (Staphylinidae) and Cyclocephala jalapensis (Scarabaeidae), that entered flowers at night and remained throughout the next day engaged in a variety of behaviors (copulation and feeding on pollen and petal tissue). Cyclocephala jalapensis, a regional endemic, is closely associated with cloud forest habitat and appears dependent on M. schiedeana for adult nutrition. Magnolia schiedeana therefore seems to possess a more specialized pollination system than temperate Magnolia species. All three populations experienced some degree of previous disturbance (cutting) and exhibited very low fertility. The average tree produced 1 flower per day, 2-4 flowers during the season, and 1 fruit. Regeneration of populations was primarily by resprouting of roots and trunk bases and not seedling recruitment. Future existence of M. schiedeana within Veracruz is jeopardized by deforestation brought about by a large human population struggling for basic necessities.