Beard,Karen H.; Vogt, Kristiina A.; Kulmatiski,Andrew 2002. Top-down effects of a terrestrial frog on forest nutrient dynamics.. Oecologia 133 :583 593.
Abstract:
Many studies have found top-down effects of
predators on prey, but few studies have linked top-down
effects of vertebrate predators to nutrient cycling rates in
terrestrial systems. In this study, large and significant
effects of a terrestrial frog, Eleutherodactylus coqui
(coqu), were recorded on nutrient concentrations and
fluxes in a subtropical wet forest. In a manipulative
experiment, coqus at natural densities were contained in
or excluded from 1 m3 enclosures for 4 months. Chemistry
of leaf wash (throughfall), foliage, and decomposed
leaf litter in the enclosures were measured as indicators of
coqu effects on nutrient cycling. Coqu exclusion
decreased elemental concentrations in leaf washes by
83% for dissolved organic C, 71% for NH4
+, 33% for
NO3
–, 60% for dissolved organic N, and between 60 and
100% for Ca, Fe, Mg, Mn, P, K, and Zn. Coqu exclusion
had no effect on foliar chemistry of plants transplanted
into the enclosures. However, coqu exclusion decreased
nutrient availability in decomposing mixed leaf litter by
12% and 14% for K and P, respectively, and increased
C:N ratios by 13%. Changes in nutrient concentrations
that occurred with coqu exclusion appear to be due to
concentrations of nutrients in coqu waste products and
population turnover. The results supported our hypothesis
that coqus have an observable effect on nutrient dynamics
in this forest. We suggest that the primary mechanism
through which they have this effect is through the