Consistency in seed-deposition patterns and the distribution of mistletoes among its host trees in an Amazonian savanna

Abstract

The present paper describes the spatial distribution of the mistletoe Psittacanthus plagiophyllus Eichl. (Loranthaceae) on its host, the cashew tree Anacardium occidentale L., in a Brazilian Amazonian savanna. Our aim was to understand the roles of bird-seed dispersers and host quality in determining the mistletoe distribution among its host trees. In 2006, we marked 118 cashews in a 4.5-ha plot and counted the number of mistletoes and the presence of seeds attached to host branches in 2006, 2007 and 2008. On average, 36% of the hosts were infected each year. The infection load and the probability of being infected increased significantly with host crown diameter. On average, 25% of the hosts received at least one mistletoe seed in each year, being taller and previously infected hosts more prone to receive seeds in all 3 years. Elaenia cristata was the main seed disperser, visiting P. plagiophyllus 48 times in 35 h of focal records. Additionally, in a field experiment, we used the presence of an infection and the host size as surrogates for host quality and tested their effect on mistletoe survivorship. After 9 months, 16.5% of seeds survived and 14% had established, but neither host conditions nor host size influenced seed survivorship. Therefore, we suggest that mistletoe distribution is a consequence of a consistent dispersal of seeds onto larger and previously parasitised hosts across years.

Non-overlap of hosts used by three congeneric and sympatric loranthaceous mistletoe species in an Amazonian savanna: host generalization to extreme specialization

“…Mature fruits are black pseudo-berries, and the single seeds are mostly dispersed by tyrant fl ycatchers through regurgitation. For instance, at least P. plagiophyllus is mainly dispersed by the small fl ycatcher Elaenia cristata (Fadini et al 2009). All mistletoe seeds are easily distinguishable from each other because they have diff erent numbers, shape, size and aspect of their cotyledons.…”

Fire and Host Abundance as Determinants of the Distribution of Three Congener and Sympatric Mistletoes in an Amazonian Savanna

“…This pattern has been frequently documented for mistletoes within individual host trees or within neighborhoods of infected trees, where bird dispersers create a positive feedback in seed deposition (Aukema 2003, Fadini et al 2009, Rist et al 2011). On the other hand, the mechanisms leading to aggregation of mistletoes at large spatial scales have been relatively less studied, and comparative studies of different mistletoe species are even rarer (e.g., Dzerefos et al 2003).…”

Sequential augmentation reveals life history and suitable conditions for colonization of the rare mahogany mistletoe in South Florida

“…Seeds can remain alive, but without above‐branch development for over 400 days and development to fruiting stage required 4.7 years on average. Studies of the mistletoe, Psittacanthus plagiophyllus , which grows on cashew in the Brazilian Amazon savanna showed 16.5% seed survival and 14% seed establishment after 9 months with no difference across host attributes (Fadini et al ). In comparison our studies indicate that seed survival depends on host and seed source.…”