Juan Carlos Berrio

Distribution and ecology of parent taxa of pollen lodged within the Latin American Pollen Database

The cornerstone of palaeoecological research, concerned with vegetation dynamics over the recent geological past, is a good understanding of the present-day ecology and distribution of the taxa. This is particularly necessary in areas of high floral diversity such as Latin America. Vegetation reconstructions, based on numerous pollen records, now exist with respect to all major vegetation associations from Latin America. With this ever-increasing number of sedimentary records becoming available, there is a need to collate this information and to provide information concerning ecology and distribution of the taxa concerned. The existing Latin American Pollen Database (LAPD) meets the first of these needs. Information concerning the ecology and distribution of the parent taxa responsible for producing the pollen, presently lodged within the LAPD, is the focus of this paper. The ‘dictionary’ describes the ecology and distribution of the parent taxa responsible for producing pollen identified within sedimentary records. These descriptions are based on a wide range of literature and extensive discussions with members of the palaeoecological community working in different parts of Latin America investigating a range of different vegetation types.

Mid- to Late-Holocene pollen-based biome reconstructions for Colombia

Abstract The assignment of Colombian pollen data to biomes allows the data to be synthesised at 10 ‘time windows’ from the present-day to 6000 radiocarbon years before present (BP). The modern reconstructed biomes are compared to a map of modern potential vegetation to check the applicability of the method and the a priori assignment of pollen taxa to plant functional types and ultimately biomes. The reconstructed modern biomes are successful in describing the composition and distribution of modern vegetation. In particular, altitudinal variations in vegetation within the northern Andean Cordilleras are well described. At 6000 BP the biomes are mainly characteristic of warmer environmental conditions relative to those of the present-day. This trend continues until between 4000 and 3000 BP when there is a shift to more mesic vegetation that is thought to equate to an increase in precipitation levels. The period between 2500 and 1000 BP represents little or no change in biome assignment and is interpreted as a period of environmental stability. The influence attributed to human-induced impact on the vegetation is recorded from 5000 BP, but is particularly important from 2000 BP. The extent of this impact increases over the Late-Holocene period, and is recorded at increasingly high altitudes. Despite these changes, a number of sites do not change their biome assignment throughout the analysis. This asynchronous vegetation response is discussed within the context of site location, non-linear response of vegetation to Late-Holocene environmental change, regionally differential signals, localised human impact and methodological artefacts.

Late Quaternary pollen records from the middle Caquetá river basin in central Colombian Amazon

Abstract Three pollen records are presented from the Pantano de Monica region (0°42′S, 72°04′W, 160 m elevation) on the lower terrace of Rio Caqueta of the central Colombian Amazonas. Ten radiocarbon dates from three cores indicate that the deposits are of Holocene age, but the pollen data suggest that the record may also contain the Late Glacial. The core Pantano de Monica 1 covers the time interval from 11,150 BP (extrapolated) to 4730 BP. During the Late Glacial and early Holocene this swamp was smaller in size and waters were more shallow than today, with abundant Mauritia palm trees. This indicates that the lower terrace of the Caqueta River was better drained than today, which might be related to changes in the drainage system and/or drier conditions during that time. Late Glacial and early Holocene vegetational changes in the rain forests surrounding the swamp Pantano de Monica indicate successional stages, probably related to changes in the drainage system and/or climate changes. Presence of Podocarpus pollen grains up to 2.6% of the total sum (and influx of 78 grains cm −2 yr −1 ) point to the regional presence of Podocarpus at the beginning of the Holocene. Evidence of Podocarpus during glacial times in other pollen records from the Amazon basin has been taken as indicative of cooling. Core Pantano de Monica 2 was taken in a small swamp (1000 m distance to Pantano de Monica 1) and starts at 4000 BP when this location was well drained. Several changes in the composition of the rain forest are documented, such as increase in disturbance (increase of Cecropia ) followed by a quick recovery (increase of Psychotria ). Protium and Caryocar tree taxa were frequent, suggesting that the lower terrace area was well drained until 3080 BP, after which small swamps developed. Core Pantano de Monica 3 is from the wet forest in between the two swamps and represents the period since 3260 BP. Pollen data show a continuously increasing presence of palms, probably Euterpe , suggesting either a transition from well-drained to less drained conditions in the lower terrace during the late Holocene, and/or a more intensive human impact of the rain forest on the lower terraces of Rio Caqueta. The three records from the lower terrace of Rio Caqueta show different forest compositions in the past and indicate that the rain forest environments were not stable during Late Glacial and Holocene times. Comparison with other data from lowland records of northwestern South America suggest that climate change is a major factor for environmental change in central Colombian Amazon.

Tropical rain-forest history from the Colombian Pacific area: a 4200-year pollen record from Laguna Jotaordó

Pollen analysis of a 5 m long core from Lake Jotaordó, located in northern ‘Chocó biogeographic area’ (5°48[.minute] N, 76°42[.minute] W) along the Pacific coast of Colombia, shows the environmental history of the rain forest during the last 4200 years. Time control has been based on 6 AMS 14C dates ranging from 4230 to 365 14C yr BP. The period of 4230 to 4053 14C yr BP shows sandy deposits and river influence and represents at that time the initial phase of the lake. The composition of the rain forest was different compared to the last 1400 years. Pioneer taxa belonging to Cecropia, Melastomataceae/Combretaceae and Moraceae/Urticaceae dominated the forest. A 30 cm thick organic rich clay from 440 to 410 cm core depth spans a period of 2600 years (from 4050 to 1450 14C yr BP), pointing to a hiatus in the sediment record, possibly caused by riverine erosion of previously deposited sediments. During the last 1400 years rain forest is characterized by Mauritiella, Euterpe/Geonoma, Iriartea, Pachira aquatica and Malpighiaceae. Floral composition of the rain forest is not constant. Abiotic dynamics caused changes in the drainage system. The presence of human settlements during the last 1000 yrs is evidenced by Zea mays and possibly also by the increase of palms.

A Pollen Atlas of Premontane Woody and Herbaceous Communities from the Upland Savannas of Guayana, Venezuela

Descriptions and photomicrographs of pollen grains from 245 angiosperm species commonly found in contemporary plant communities of the upland savannas of Guayana, Venezuela are presented. Most of the species are frequent in woody communities as shrublands, evergreen montane and gallery forest of the premontane altitudinal belt (400–1800 m above sea level). In contrast with previous contributions which emphasised species from highland and/or flooded environments, most species considered here grow on lowland to upland well-drained soils. The high numbers of taxa considered herein means that the utility of this contribution transcends palaeoecology and impinges on, for example, reproductive biology, forensic palynology, aerobiology and melissopalynology in Guayana and the wider Neotropical realm.

Changing depositional environments in the Colombian Fúquene Basin at submillennial time-scales during 284-27 ka from unmixed grain-size distributions and aquatic pollen

In a ~60 m long record reflecting the period from 284 ka to 27 ka we analysed grain size distributions (GSD), organic carbon content, and aquatic pollen assemblages at 1-cm increments. The 4768-points time series show with ~60 yr resolution the dynamic history of Lake Fuquene (2540 m alt., 4° N lat.) of the northern Andes during two full interglacial-glacial cycles. GSD show proportions of clay, fine silt, coarse silt, and sand evidencing the location of the sediment source (proximal vs distal) in relation to the drilling site, and available energy to transport sediments in the catchment area. Loss-on-ignition (LOI) values reflect estimates of the abundance of organic matter (OM) in the sediments. Aquatic pollen were grouped into assemblages characteristic of deep water, shallow water, swamp, and wet lake shore environments, reflecting a hydrological gradient sensitive for lake level changes. The End-Member Modelling Algorithm (EMMA) showed that 4 end-members (EMs) explain an optimal proportion (70%) of the observed variation. EMMA is able to unmix GSD of lacustrine sediments in a genetically meaningful way allowing EMs to be interpreted in past depositional and environmental settings. Most unexplained variability is located in the fraction of coarse sediment. OM content was estimated on the basis of LOI data and formed a fifth EM that mainly indicates presence of peat. Changes concur with submillennial-scale variability established in other proxies from this record (Groot et al., 2011). Periods with distinct sediment compositions are 284-243 ka (mainly MIS 8), 243-201 ka (mainly MIS 7), 201-179 ka (mainly MIS 7/6 transition), 179-133 ka (mainly MIS 6), 133-111 ka, (mainly MIS 5e) 111-87 ka (mainly MIS 5d-5b), 87-79 ka (mainly MIS 5a), 79-62 ka (mainly MIS 4), and 62-27 ka (MIS 3) showing sedimentological regimes are climate driven.

The dynamic history of the upper forest line ecotone in the northern Andes

In the Andean cordilleras very conspicuous ecotones can be found. The transition from continuous upper montane forest to treeless herbaceous vegetation, regionally known as “paramo” (Cleef 1981; Luteyn 1999) is known as the “upper forest line” (UFL) or “timber line” (Holtmeier 2009). Above the UFL trees may occur forming small patches with diameters of ten to several hundreds of metres. The elevation where individual trees find their altitudinal limits is at significantly higher altitudes and this limit reflects the “upper tree line”. In the Colombian Andes the upper tree line, most formed by dwarf trees of Polylepis, may be up to 800 m above the UFL. Therefore, it is relevant to differentiate between both ecotones. Across the Andes the altitudinal position of the UFL varies much depending latitude (Schmithusen 1976) but in the area under consideration located between 0 and 11°N the altitudinal position of the UFL mostly varies between 3,000 and 3,800 m. In this paper we focus on the tropical Andes of northern Ecuador and Colombia. The spatial and temporal dynamics of the UFL ecotone, which has scientific and economic relevance is explored and discussed.

Vegetation disturbance and human population in Colombia – a regional reconstruction

Palaeoecologists using pollen to map vegetation since the last ice age have noted numerous changes – which they feel increasingly obliged to blame on humans. These changes, such as deforestation or the dominance of certain plants, may happen suddenly or take place over thousands of years. The authors study the pollen record in Colombia, identify plants diagnostic of cultivation or disturbed ground (“degraded vegetation”) and use them to map human activities by proxy. They show how the people move and the landscape changes between 5000 BP and the present day, from the coast inland, and from the lowlands up into the Andes.

Late-Holocene gallery forest retrogression in the Venezuelan Guayana: New data and implications for the conservation of a cultural landscape

Fire is considered a major threat to forest conservation in the Neotropics. Palaeoecological studies are critical for understanding the long-term interactions of climate, fire, and human activities in the savanna–forest dynamic. Here, new data from palynological analyses conducted in sedimentary records from the northern edge of the Amazon Basin, the Gran Sabana, southeast of Canaima National Park (CNP) are presented. Four radiocarbon ages from Quebrada Kowana (QK) and two for Ariwe Fernland (AF) records showed that both are late-Holocene age (with extrapolated basal ages of 3100 and 3400 cal. yr BP, respectively). Both showed the occurrence of gallery forest until 1800 (QK) and 1600 (AF) cal. yr BP, with forest taxa reaching 60% and 40% of the terrestrial pollen sum, respectively. The main forest taxa were Celastraceae, Moraceae/Urticaceae, Schefflera, Protium, and Mahurea (QK) and Dimorphandra, Protium, Schefflera, Tachigali, and Blepharandra (AF). Savanna herbs (mainly Poaceae) reached 40–50% (QK) and 60% (AF). The high abundance of savanna herbs together with the low occurrence of mature forest taxa, and high abundance of pioneer taxa, suggests that the former forests comprised very open and disturbed forest-belts, surrounded by savannas. Since 1800 (QK) and 1600 (AF) cal. yr BP, forest taxa dropped to 10% and 5%, respectively, suggesting the substitution of forests by herbaceous communities. The high abundance of charcoal recorded from the beginning of the records to about 1800–1600 cal. yr BP suggests that recurrent fires spreading from neighboring savannas were reaching the former forest, causing compositional changes and triggering forest reduction. Fires were very likely human-made, but highly controlled by climate. Hence, forest substitution happened when a combination of local fires and droughts was given in every record. Results agree with those from other localities in the CNP in confirming the occurrence of regional-scale gallery forest degradation during the late Holocene.

Using Paleoecological Data to Define Main Vegetation Dynamics Along the Savanna–Forest Ecotone in Colombia: Implications for Accurate Assessment of Human Impacts

In recent decades there has been increasing interest, from scientists of many disciplines, in the origins and dynamics of tropical savanna–forest boundaries. These boundaries are rarely present as a smooth gradient from tropical forests to scattered trees and open grassland (Bond and Parr 2010); rather, they are often patchy and irregular, occurring where at first sight no apparent driver for an ecosystem shift is apparent (Sarmiento 1984). In general terms, savanna ecosystems cover approximately 40% of the tropics or 23 million km2 (Cole 1986; Gardner 2006) and host around one-fifth of the world’s human population (Young and Solbrig 1993). These people are imparting a growing impact on savanna systems, as agriculture and other subsistence activities occupy increasingly larger land areas (Gardner 2006).