On the interpretation of fossil Poaceae pollen in the lowland humid neotropics (original) (raw)
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Review of Palaeobotany and Palynology, 1997
Stable carbon isotope differences between ecologically distinct groups of Poaceae (C3 and C4 photosynthetic groups) provide a means of isotopically subdividing grass pollen in paleovegetation studies. We examined the isotopic composition of bulk grass plant tissue, untreated pollen, and chemically treated pollen, from several C3 and C4 grass species. Based on our data, untreated pollen is isotopically similar to the host plant from which it is derived, although small, random differences between plants and pollen occur. Methods of pollen concentration involving carbon-bearing compounds can alter the isotopic composition of recovered pollen, and in some cases, make pollen from different grass types isotopically indistinguishable. We conclude that the isotopic composition of physically separated Poaceae pollen should be an important means of determining the proportion of grasses as long a carbon-bearing chemicals are not used in sample preparation. The carbon isotope composition of pollen should provide a new means of determining paleoclimatic conditions in grassland environments and aid in identifying the origin of the C4 photosynthetic pathway in the geologic past.
Biogeosciences
The collection of modern, spatially extensive pollen data is important for the interpretation of fossil pollen assemblages and the reconstruction of past vegetation communities in space and time. Modern datasets are readily available for percentage data but lacking for pollen accumulation rates (PARs). Filling this gap has been the motivation of the pollen monitoring network, whose contributors monitored pollen deposition in modified Tauber traps for several years or decades across Europe. Here we present this monitoring dataset consisting of 351 trap locations with a total of 2742 annual samples covering the period from 1981 to 2017. This dataset shows that total PAR is influenced by forest cover and climate parameters, which determine pollen productivity and correlate with latitude. Treeless vegetation produced PAR values of at least 140 grains cm −2 yr −1. Tree PAR increased by at least 400 grains cm −2 yr −1 with each 10 % increase in forest cover. Pollen traps situated beyond 200 km of the distribution of a given tree species still collect occasional pollen grains of that species. The threshold of this long-distance transport differs for individual species and is generally below 60 grains cm −2 yr −1. Comparisons between modern and fossil PAR from the same regions show similar values. For temperate taxa, modern analogues for fossil PARs are generally found downslope or southward of the fossil sites. While we do not find modern situations comparable to fossil PAR values of some taxa (e.g. Corylus), CO 2 fertilization and land use may cause high modern PARs that are not documented in the fossil record. The modern data are now publicly available in the Neotoma Paleoecology Database and aid interpretations of fossil PAR data. Review statement. This paper was edited by Anja Rammig and reviewed by Simon Connor and two anonymous referees.
Ecological Questions, 2009
The results of palynological analyses of the Holocene deposits and modern pollen deposition in Poland and Finland are used to illustrate the progress in pollen analysis-the main palaeoecological method. The increased potential of modern palaeoecology for reconstruction of vegetation and for drawing conclusions on other environmental variables (climate, water conditions, landscape, anthropogenic disturbances) is demonstrated. Pollen analysis-develops at present interpretive tools for precise reconstruction of the structure and composition of vegetation and climate conditions. The progress consists in the quantitative presentation of pollenvegetation-climate relationships based on the examination of modern pollen deposition. The application of numerical analyses to pollen data allows correlating pollen spectrum features with the landscape/vegetation type. Special attention is paid to the Holocene vegetation changes of the transitional zone between boreal forest and tundra in the areas subjected to weak anthropopression (e.g. Lapland), which reflect climatic changes. Databases of modern pollen analogues are based on analysis of samples of surface mosses and contents of Tauber traps. These traps are used in Poland in investigations conducted as a part of the Pollen Monitoring Programme (http://pmp.oulu.fi). The correlation of Tauber-trap data with aerobiological ones contributes to understanding of the relationship between pollen production and climate elements. Additionally, the precise C 14 dating allows a near-annual resolution in fossil deposits to be obtained more frequently. Due to time scales comprising hundreds of years, pollen analysis can provide means to resolve questions inaccessible for direct observation.
Modern pollen-and phytolith-vegetation relationships at a wetland in northeastern South Africa
South African Journal of Botany, 2023
In palaeoenvironmental reconstructions, few studies have focused on comparing the presence of pollen and phytoliths in surface sediments to the local vegetation. Notwithstanding inherent differential pollen and phytolith preservation, production, and dispersal, which affect their recovery and interpretation in sediment archives, there remains a need to explore modern pollen-vegetation, phytolith-vegetation and pollen-phytolith relationships to improve palaeoenvironmental reconstructions. We carried out palynological and phytolith analysis on six surface sediment samples linked to the botanical survey of five vegetation survey plots at Gustav Klingbiel Nature Reserve, Mpumalanga province in northeastern South Africa, to understand the relationships between the modern pollen and phytolith assemblages in the surface sediments and the contemporary vegetation of the study area. Correspondence Analysis (CA) was undertaken to examine the fingerprint of the local vegetation in the modern pollen-phytolith assemblage and evaluate whether the phytolith and pollen assemblages were tracking each other. CA illustrated that pollen and phytolith proxies are not tracking the same primary vegetation signals; modern pollen assemblages best represent the components of forest and wetland vegetation. In contrast, modern phytolith assemblages best represent grassland vegetation. Our study shows that differential pollen and phytolith preservation, production and dispersal significantly affect sediment records more than anticipated, thus combining multi-proxies (e.g., phytoliths, pollen) provides a more accurate basis for the interpretation of fossil spectra in palaeoenvironmental reconstructions.
Pollen preservation zones as an interpretative tool in Holocene palynology
Review of Palaeobotany and Palynology, 2010
Numerous taphonomic and statistical factors influence the composition of the palynological record and the interpretation of pollen count data is far from simple. Quantification of the condition in which the pollen has been preserved can increase the confidence of such interpretation by highlighting parts of the record that are likely to have been influenced by changing taphonomy. Despite the benefits, preservation analysis is a relatively under-used technique and there remain a lack of observational data from a wide range of geographical locations and depositional contexts. This paper presents the results of detailed pollen preservation analyses completed for four in-filled basins from Holderness, lowland eastern England. We examine the Holocene pollen records in detail and employ what we believe to be a novel methodologythe definition and assignment of Local Pollen Preservation Zonesto help assess patterns of pollen deterioration, both within and between sites. The data obtained are used to consider a range of topics, including the evidence for local and regional influences on pollen deterioration frequency, relationships between preservation and broad-scale aspects of the depositional environment, and the origins of occasional incidences of pollen from major arboreal taxa. Evidence for two different forms of perforation corrosion is also discussed. The outcomes of this study are of relevance to palynological investigations over a range of timescales, not just the Holocene, and we hope that this contribution will stimulate further consideration of the role that pollen preservation analysis can contribute to palynology as a discipline.
Pollen Preservation in Alluvial Soils: Implications for Paleoecology and Land Use Studies
Soil Science Society of America Journal, 2019
Wetland Soils Note Floodplain landscapes with fluctuating water tables are nontraditional sites for palynology studies, and therefore intrinsic alluvial soil properties and their relationship to pollen preservation are poorly understood. The primary objective of this study was to identify soil properties that are most related to pollen preservation in floodplains to aid in predicting soil pollen presence and abundance. Our results indicate that all organic soil horizons had preserved pollen, whereas mineral horizons had variable pollen concentrations (range, 0-59,000 grains g −1 soil). Mineral samples with preserved pollen (>0 grains g −1 soil) had significantly greater (p < 0.001) soil organic matter (SOM) and silt + clay, and were located closer to the modern soil surface. Regression analyses indicated that only SOM and C/N ratios were significant predictors of pollen abundance. The guidelines developed in this study can be used to identify samples that likely contain enough pollen for palynological analysis and save future researchers considerable laboratory time, effort, and cost. Abbreviations: SOM, soil organic matter. R iparian soils form in alluvial settings representing continuous and episodic depositional events where coarser materials are indicative of higher energy deposition and thick buried horizons are indicative of landscape stability (Blazejewski et al., 2009; Ricker et al., 2012). Determining the timeframes of deposition and stability is critical for understanding the effects of land use and climate change on watershed characteristics and functions. Classic radiometric techniques, such as 14 C, 210 Pb, or 137 Cs, are difficult to apply in floodplains because of sediment reworking, nonuniform parent material, a heterogeneous C-rich soil matrix, and root inclusions (Kenyon and Rutherfurd, 1999; Ricker et al., 2012). Thus, additional relative dating techniques are needed to corroborate radiometric dates to determine riparian depositional chronologies. Fossil pollen and spores (palynomorphs) have been used as a relative dating technique since the late 1800s (Faegri and Iversen, 1975). Most pollen studies evaluate paleoclimate, plant succession, and pre-historical vegetation structure (Baker et al.
Pollen Grains, Landscapes, and Paleoenvironments
Editora FIOCRUZ eBooks, 2014
All the contents of this work, except where otherwise noted, is licensed under a Creative Commons Attribution 4.0 International license. Todo o conteúdo deste trabalho, exceto quando houver ressalva, é publicado sob a licença Creative Commons Atribição 4.0. Todo el contenido de esta obra, excepto donde se indique lo contrario, está bajo licencia de la licencia Creative Commons Reconocimento 4.0.
www.scielo.br/aabc A Holocene pollen record of savanna establishment in coastal Amapá
2006
presented by ALCIDES N. SIAL The main goal of this study was to investigate how climate and human activities may have influenced ecotonal areas of disjoint savannas within Brazilian Amazonia. The fossil pollen and charcoal records of Lake Márcio (Amapá) were used to provide aHolocene palaeoecological history of this region. Detrended correspondence analysis (DCA)was used to enhance the patterns of sample distribution along the sediment core. A marked vegetation change from closed forests with swamp elements to open flooded savanna at c. 5000 yrs BP was evident from the pollen record. Charcoal analysis revealed a pattern of increased accumulation of particles coincident with the establishment of savannas, suggesting higher fire frequency and human impacts near the lake. A 550-year sedimentary hiatus suggests that the lake depended heavily on floodwaters from the Amazon River, and that it became suddenly isolated from it. When sedimentation restarted in the lake, the environment had c...
From Modern Pollen-Plant Relationships to Holocene Vegetation Diversity Reconstructions
2020
of pollen and spores from sediment sequences and presenting the results in terms of a pollen diagram were first introduced by Swedish naturalist and geologist Lennart von Post (von Post, 1918) and have been used up until today. Pollen analysis has an important role in studying vegetation history and historical environments, and provides useful proxies of past climatic conditions and various other factors (Davis, 2014; Birks et al., 2016; Parnell et al., 2016). Shortly after the introduction of pollen analysis, in the 1920s, it was adopted in Estonia by Paul William Thomson, who laid the foundations for interpreting post-glacial vegetation history in the Baltic region (Thomson, 1925). After that, many prominent studies have used pollen analysis to elucidate vegetation history, biostratigraphy, archaeology, sea level fluctuations, and human impact in Estonia (e.g. Ilves