Abstract:
Questions: To assess the relationship between modern pollen rain and Andean
montane forest vegetation for diversity, and provide a basis for interpretations of
palaeoecological data in the northern Andes, we asked: (1) can the reduction of
plant and pollen data to family level preserve information about diversity in both
data sets; (2) how precisely do tree pollen and spore types represent richness patterns
along an altitudinal gradient on tropical mountains; and (3) how similar
are tree pollen and spore family richness in relationship to tree family richness?
Location: Tropicalmontane rain forests, Podocarpus National Park in the Andes
of South Ecuador (3°S, 79°W, 1000–3000 ma.s.l.).
Methods:We analysed tree diversity and species composition in three different
rain forest types: Premontane (PMF), lowermontane (LMF) and uppermontane
(UMF).We investigated modern pollen rain using pollen traps. After testing the
reliability of a taxonomic surrogacy on the plant data, we compared abundance
and representation, as well as diversity of the two data sets at family level. This
was done using rarefaction and Sørensen indices.
Results: The correlation between tree species and families was high (r = 0.81,
P < 0.001). Sample rarefaction on tree pollen and plant family data revealed
highest pollen diversity on sites of the UMF, but highest tree diversity on LMF
and PMF sites. The Sørensen indices indicate down-drift of pollen from higher
altitudes in PMF and LMF and up-drift in UMF. Between 1% and 50% of pollen
taxa of each sample originate fromoutside the plot.
Conclusions: Taxonomic surrogacy at family level is a good tool for comparing
presence–absence patterns of plant and pollen data in tropical regions with high
tree diversity. On a family basis, pollen presence–absence data represent the corresponding
tree vegetation data, but uncertainties increase with decreasing altitude.
The higher diversity in pollen data of the UMF, but slightly lower diversity
in the LMF and PMF, can at least partly be explained by wind patterns, local
abundance of shrubs and herbs and differences in evenness.
