Effect of manure composition on seedling emergence and growth of two common shrub species of Southeast Alaska

• Main Authors: Traveset, Anna, Bermejo, Teresa, Willson, Mary F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Kluwer Academic Publishers 2001
• Subjects: Ursus arctos; Alaska
• Online Access: http://hdl.handle.net/10261/54400; https://doi.org/10.1023/A:1013282313035

The idea that fecal material accompanying vertebrate-dispersed seeds at deposition sites plays an important role in enhancing seed germination and seedling survival has, surprisingly, little empirical support. The present study attempts to experimentally test this hypothesis. We examined the effect that manure composition from brown bears (Ursus arctos), important seed dispersers of Rubus spectabilis and Vaccinium ovalifolium/alaskaense in the temperate rainforests of Southeast Alaska, has on seedling emergence and growth of these two fleshy-fruited species in their natural habitat. The seeds of Rubus spectabilis showed a significantly higher germination rate in manure composed of animal material (mainly deer hair and bones) than in manure consisting of either fruit pulp or vegetation fiber and than in controls (potting soil with no manure added). The final number of germinated Rubus seeds was similar between the animal material and the fruit pulp treatments, perhaps due to similar water retention capacities, but was significantly higher than in the vegetation fiber treatment and the control. The germination patterns of Vaccinium seeds, in contrast, appeared to be unaffected by the composition of manure in which they were embedded. Seedlings of both species grew faster, and in the case of Rubus produced more leaves, when manure consisted of animal material. A principal constituent of bone is calcium phosphate, which may provide important minerals to growing plants. Manure containing vegetation fiber also enhanced seedling growth compared to manure with fruit pulp or the control. For Rubus, manure with fruit pulp did not affect seedling length significantly, although the number of leaves per seedling was greater in this treatment than in the control. We conclude that the influence of frugivores on the final fate of seeds of fleshy-fruited plants appears to depend not only upon commonly considered factors such as distance of dispersal, treatment in the digestive tract, and location of deposition, but also on what ...