Pollen dispersal and representation in a neotropical rain forest

Abstract

Results of 3 years of pollen trapping on Barro Colorado Island, Panama, are presented. Minimum pollen dispersal distances are estimated for the most abundant pollen taxa. Dispersal distances for some taxa appear to be as low as 5 m, while for other taxa at least 50% of the trapped pollen had travelled more than 40 m. No consistent pattern of spatial variation was reflected in the pollen rain, however, samples close to large canopy gaps had exceptional abundances of ‘disturbance’ taxa. A preliminary analysis of the representation of canopy components indicates that as much as 19% of pollen caught in the traps was derived from large tree species.

Amazonian paleoecological histories: one hill, three watersheds

“…Poaceae and charcoal, the great indicators of an opening of forests are rare throughout. Poaceae never exceed 5%, a proportion that we have earlier suggested is typical of closed forest environments (Bush, 1991;Bush and Colinvaux, 1988;Bush and Rivera, 1998).…”

“…Even when pollen traps are set directly beneath Podocarpus trees only 20% Podocarpus pollen was recovered (Bush, 2000). When Podocarpus was locally abundant, but not directly overhead, <1% of Podocarpus pollen was feiund (Behling et al, 1997), and in >90% of lowland traps there was no Podocarpus whatsoever (Bush, 2000;Bush and Rivera, 1998). The inescapable conclusion is that for Podocarpus to be represented with 3-10%, as found in all three lakes, these trees were abundant in the local forest, and were probably growing within the watersheds of all the lakes.…”

“…Pennington et al (2000) argued that many of the pollen taxa documented by Colinvaux et al (1996) in the Pata record could equally come from caatinga as from mesic forest. Of course, many taxa are shared between habitats, but Pennington et al (2000) ignore the quantitative aspect of the pollen record and the wealth of modem pollen rain data from savanna and caatinga (Bush, 2000;Salgado-Labouriau, 1979;Salgado-Labouriau, 1997;Salgado-Labouriau et al, 1997) and many types of mesic tropical forest (Behling et al, 1997;Bush, 1991;Bush, 2000;Bush and Rivera, 2001;Bush and Rivera, 1998;Grabandt, 1980;Grabandt, 1985;Rodgers and Horn, 1996;Salomons, 1986). In savanna systems Poaceae pollen often reach values of 50-90% (Salgado-Labouriau et al, 1997ab), and in open woodland settings Poaceae pollen is seldom <20%.…”

Estimating Neotropical palaeotemperature and palaeoprecipitation using plant family climatic optima

“…Pollen data in particular can be biased by the differential representation and preservation of taxa due to pollination mechanism (Bush and Rivera, 1998). Anecdotal evidence also suggests that preservational differences due to pollen morphology (e.g.…”

Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years ago

“…Notwithstanding some of the anomalies mentioned, the biomisation method applied to Latin American pollen data can reconstruct large-scale vegetation patterns despite many pollen taxa having different ecological interpretations under different environmental settings (Grabandt, 1980), representation of parent vegetation by pollen likely to be subject to inter-annual variability (Behling et al, 1997b), and tropical vegetation is difficult to reconstruct through pollen assemblages (Bush, 1991;Mancini, 1993;Bush and Rivera, 1998;Behling et al, 1997). These factors demonstrate the importance of basing the input matrices for the biomisation process on all the available ecological information that allowing for the multiple assignment of the pollen taxa to the PFTs.…”