Masting has different effects on seed predation by insects and birds in antarctic beech forests with no influence of forest management

SOLER, ROSINA; ESPELTA, JOSEP MARIA; LENCINAS, MARÍA VANESSA; PERI, PABLO L.; MARTÍNEZ PASTUR, GUILLERMO

FOREST ECOLOGY AND MANAGEMENT

ELSEVIER SCIENCE BV

Año: 2017 vol. 400 p. 173 - 180

0378-1127

Mast seeding is characteristic of manylong-lived tree species and widely proposed as a mechanism to reduce seedpredation. However, whether the efficiency of this reproductive response mayvary depending on type of seed predator (e.g., invertebrates vs. vertebrates)or depending on local characteristics, remains seldom explored. We evaluatedfor 8 yrs the patterns of seed production in antarctic beech (Nothofagus antarctica) forests related to management and itsinfluence on insect and bird predispersal seed predation. Along the study,mature seed production was highly variable across years(the population-level coefficient of variation, CVp: 0.98?1.14) andspatially synchronized (Pearson correlation coefficient: 0.83?0.86). Foresttype (primary unmanaged, secondary-growth and managed stands) did not influencethe amount of seed production nor masting patterns. Mean yearly seed predationby insects was higher than by birds, and their relationship with seedingpatterns differed: i.e., while the proportion of seeds predated by insectsincreased during non-mast years maximum bird predation occurred in mast years.Therefore, predation by insects and birds showed a strong negativerelationship. Our results suggest that effectiveness of masting to escape seedpredators may be highly depend on the type of predator. We address whether thiseffect may be due to differences in life history traits among the seed predatorsinvolved (i.e., degree of host specificity, dispersal ability or the durationof the life-cycle) and whether an ??imperfect? control of avian seed predationmay partially be advantageous for the dynamics of the masting species toenhance seed dispersal.