Spatiotemporal variation of fruit digestible-nutrient production in Florida's uplands

We examined annual total digestible nutrient (TDN) production by fruits of eight species (Quercus chapmanii, Q. geminata, Q. inopina, Q. laevis, Q. myrtifolia, Carya floridana, Sabal etonia, Serenoa repens) that account for the major proportion of TDN production by fruits and seeds in Florida’s xeric upland associations (southern ridge sandhill, sand pine scrub, scrubby flatwoods). Mean annual fruit TDN of all species combined over a 27-year span in sandhill and scrub and 24 years in scrubby flatwoods was highest (45.4 kg/ha) in sandhill, intermediate in scrubby flatwoods (28.8 kg/ha), and lowest in scrub (14.2 kg/ha). Sandhill fruit TDN production was the least variable across years while scrub showed the most variability. Oaks accounted for the major proportion (68-76%) of fruit TDN in all associations. Among oaks, Q. myrtifolia was the major producer (24-56%) and Q. laevis the poorest (0.2-3%). Although annual combined fruit TDN production varied similarly among associations across years, annual fruit TDN production of C. floridana, oaks, and palmettos within associations was not significantly correlated with the exception of C. floridana vs. oaks in scrubby flatwoods. Among plant groups, correlations between fruit TDN productions across associations were significant for oaks in all cases and for C. floridana in most contrasts, but palmetto fruit TDN production was not significantly correlated in different associations. Seven of eight species exhibited significant periodicities in fruit TDN production in one or more association ranging from 2.0 to 4.8 years. Potential consumers of fruit TDN production recorded on the study area include 15 mammals, five birds, one reptile, and invertebrates.