Modern pollen–vegetation relationships along transects on the Whangapoua Estuary, Great Barrier Island, northern New Zealand

Abstract

Aims To quantify pollen-vegetation relationships from saline to freshwater in an estuarine gradient from surface samples of the modern pollen rain, to allow more accurate interpretations of the stratigraphic palynological record.Location Whangapoua Estuary, Great Barrier Island, northern New Zealand.Methods Six transects were laid out along a vegetation sequence running from estuarine mud to freshwater swamp. Along these transect lines, 108 plots were sampled for vegetation and surface sediments from wet sand, mud, plant litter or moss (sand and mud sites are inundated by most tides, other sites less frequently). All sediment samples were analysed for pollen. The relationships between plant species frequency and pollen representation were examined at a community scale using twinspan and ordination analyses, and for individual species using fidelity and dispersibility indices, regression and box-plot analyses. ResultsThe quantitative relationships between source taxon vegetation frequency and its pollen representation varied between species due to differential pollen production and dispersal. twinspan of the surface pollen samples suggests five vegetation types: (A) mangrove (Avicennia marina); (C) Leptocarpus similis salt meadow; (D) Baumea sedges; (E) Leptospermum shrubland; and (F) Typha/Cordyline swamp forest. The (B) Juncus kraussii community is not represented palynologically owing to the destruction of its delicate pollen grains during acetolysis of samples. Detrended correspondence analysis places these communities on an estuarine-to-freshwater gradient. However, pollen assemblages at the seaward end of the salinity gradient are less clearly representative of the associated vegetation than those at the landward end, probably because the open vegetation at the former allows the influx of wind-and water-dispersed pollen from surrounding vegetation. Main conclusionsThe vegetation pattern (zonation) at Whangapoua is reflected in the pollen rain. When the long-distance and over-represented pollen types are excluded, five out of six of the broad vegetation communities can be identified by their pollen spectra. Species with high fidelity and lowto-moderate dispersibility indices can be used to identify the vegetation types in the sedimentary sequences. The more open vegetation types at the 'marine end' of the sequence tend to be 'overwhelmed' by regional pollen, but the nature of the sediments and the presence of discriminatory species (e.g. A. marina, Plagianthus divaricatus, Cordyline australis), even in small amounts, will allow correct identification of the local vegetation represented in sedimentary palynological sequences. A box-plot analysis indicates that the pollen and spore types A. marina (mangroves), Sarcocornia quinqueflora (salt meadow), P. divaricatus (sedges), Gleichenia (shrubland) and C. australis (swamp forest) are highly discriminatory in relation to vegetation type. These discriminatory palynomorphs help with the

Assessing the use of mangrove pollen as a quantitative sea‐level indicator on Mahé, Seychelles

“…Another key difference between these studies and the Seychelles sites is that the presence of Avicennia pollen species appears to be better associated with the presence of parent plants than we find in this study. A high Avicennia pollen-plant association has also been found in other surface sediment and pollen trap studies in Brazil, New Zealand and Colombia (Behling et al, 2001;Deng et al, 2006;Urrego et al, 2010). It is possible that if the pollen monitoring was conducted over several years (rather than only one as in this study) the traps would have been able to capture multi-year mangrove flowering cycles (Tomlinson, 2016).…”

Modern pollen and non-pollen palynomorph assemblages of salt marsh and subtidal environments from the Ría de Vigo (NW Iberia)

“…These abiotic determinants have a direct influence on the Galician marsh plant zonation (Sánchez et al, 1996(Sánchez et al, , 1998 and also control the sedimentation rates and local preservation conditions of palynomorphs (Chmura et al, 1999;Tsui and Hyde, 2004;Deng et al, 2006). Therefore, differences in pollen spectra between vegetation types showed by clustering (Fig.…”

“…For instance, Juncaceae pollen does not preserve well and might be destroyed by acidic treatment (Deng et al, 2006), and plants from the genus Spartina might be reproducing mainly by asexual propagation (Marchant and Goodman, 1969). Therefore, high marsh sediments colonized by Juncus maritimus and Spartina patens are expected to have a lower local pollen representation.…”

A pre‐deforestation pollen‐climate calibration model for New Zealand and quantitative temperature reconstructions for the past 18 000 years BP

“…Licitis, 1953;Moar, 1970;Pocknall, 1978;McGlone, 1982;Macphail and McQueen, 1983;Bussell, 1988;Horrocks and Ogden, 1994;McGlone and Moar, 1997;Elliot, 1999;McGlone and Meurk, 2000;Deng et al, 2006) and some broad conclusions can be made with confidence. Most pollen and spores originating from beyond the local wetland site vegetation come from a limited number of tall, wind-pollinated tree taxa.…”