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1.
Jaromir Beneš Jan Kaštovský Romana Kočárová Petr Kočár Klára Kubečková Petr Pokorný Petr Starec 《Vegetation History and Archaeobotany》2002,11(1-2):107-120
The stone fortification of Prague Old Town was constructed shortly after A.D. 1230. Large-scale archaeological and archaeobotanical
research has been carried out in this area in recent years. The deep moat and the drainage ditch have been excavated at several
places in front of a line of former ramparts. During the initial period of their existence, the moat and the ditch contained
only minimal waste. A sudden change in the management of these features occurred at the beginning of the 14th cent., when
they started to be filled with large amounts of rubbish. This article concentrates on the evaluation of these rubbish strata
at three profiles through the drainage ditch and one profile through the dry moat. The results of plant macro-remains (including
wood), pollen, and diatom analyses clearly demonstrate the development of the local (aquatic) environment from being relatively
clean to highly polluted. An actualistic (phytosociological) approach was adopted to reconstruct the local environment of
the town periphery in detail, and to distinguish a variety of habitats that were situated in the economic hinterland of the
city. Some species from the rich assemblages of plant remains are interpreted in terms of their use in High Medieval households.
Diatom analysis completes the picture by providing the proxy data on water quality history in the drainage ditch.
Received September 15, 2001 / Accepted May 21, 2002 相似文献
2.
Irmeli Vuorela Matti Saarnisto Terttu Lempiäinen Jussi-Pekka Taavitsainen 《Vegetation History and Archaeobotany》2001,10(3):121-138
The village of Pegrema in Karelia may be regarded as a Stone Age innovation centre in the large Lake Onega area. Two pollen
and plant macrofossil diagrams are presented which represent the first contribution to the study of human impact in the area
using anthropogenic pollen indicators. A continuous but sporadic human presence from the Mesolithic onwards is demonstrated.
While there is no archaeological evidence relating to the period 4200–3000 B.P., the pollen data suggest continuous, though
rather sparse human presence. The data do not support any natural catastrophes in Pegrema as has been suggested elsewhere.
Cerealia pollen is recorded earlier than expected (c. 5000 B.P.=. In the Bronce Age and Iron Age, the settlement of the Zaonezhye
peninsula is reflected by a slight increase in herb pollen representation, sporadic Cerealia pollen and several periods of
regression in Picea. The long introductory period of agriculture to the area, as well as the similarities and discrepancies between different
sources of evidence (palaeoecological, archaeological and historical) are discussed at some length. The start of land clearance
for permanent cultivation in the profile Pegrema S was dated to the late 13th century. The beginning of more intensive field cultivation in the 15th century is clearly seen in the pollen succession at both localities. The fluctuation in anthropogenic indicators can be related
to population density based on historical data. The village of Pegrema was depopulated in 1956 which is reflected in a distinct
decline in settlement indicators.
Received February 17 / Accepted May 19, 2000 相似文献
3.
The town of Carquefou, some 10 km northeast of Nantes on the left bank of the river Erdre, occupies a site long associated
with human activity. During road construction east of the town, ditches, enclosures and post holes characteristic of the late
la Tène were discovered at the locality of “Le Clouet”, which led us to obtain core samples from a nearby peat bog. These
investigations indicated the changes in vegetation since 3915±95 uncal B.P., [2828 (2459) 2074 cal B.C.]. The slopes in the
surroundings of the bog have been relatively treeless since the Bronze Age, but a very open woodland vegetation composed of
Tilia, Corylus and Quercus has been maintained until the present day. In the area around the bog, and Alnus wood with an undergrowth of Cyperaceae was the dominant vegetation, despite some changes probably related to human occupation
since the Bronze Age. Beginning at 955±35 uncal B.P. [1004 (1036, 1144, 1146) 1181 cal A.D.], in the Middle Ages, the alders
disappeared almost totally, apparently because of clearance or an increase in water level. Human presence led to intensified
cultivation of different crops including Cannabis and especially Cerealia. Finally, the presence of a variety of anthropogenic indicator plants (Cichorioideae, Asteraceae,
Plantago lanceolata, etc.) suggests that cattle were reared in the vicinity of the site.
Received May 22, 2000 / Accepted March 29, 2001 相似文献
4.
Castor Muñoz Sobrino Pabio Ramil-Rego Manuel Antonio Rodríguez Guitián 《Vegetation History and Archaeobotany》2001,10(1):7-21
A new core taken from a site in the Sierra de Courel range of mountains in the northwest Iberian peninsula, Spain, enables
a palaeoenvironmental reconstruction to be made of the biological events resulting from climatic changes and human activities
during the last 17,000 years in the area. The sequence begins with a phase characterised by the dominance of Gramineae (Poaceae)
and Pinus. A markedly arid period with prevalence of Artemisia pollen occurred between 17,5000 and 15,500 uncal. B.P. Subsequently, a succession of woodlands with Betula, Pinus and other mesophilous and thermophilous trees was recognised during the period 15,500-13,500 uncal. B.P. Between 13,500 and
10,300 uncal. B.P. herbaceous vegetation formations indicating moister conditions dominated the pollen record, although a
maximum of Gramineae has been dated during the period 11,300-10,300 uncal. B.P. Comparison with other pollen data from neighbouring
mountains allows an interpretation of the vegetation changes during the glacial/interglacial transition in the mountains of
northwest Iberia. The Holocene pollen record from the site does not differ markedly from other records in the area, tree expansion
occurring before 10,000 uncal. B.P. and high values of deciduous Quercus mixed with other trees and shrubs persisting until 3500 uncal. B.P., when increased human activities are shown by a fall
of the tree pollen percentages.
Received July 7, 1999 / Accepted May 22, 2000 相似文献
5.
Leif Björkman 《Vegetation History and Archaeobotany》2001,10(4):201-210
A pollen record from a small peatland located on Kullaberg in northwestern Sk?ne, southern Sweden, revealed that grazing
pressure might have been the major disturbance agent controlling the vegetation, at least from ca. 1500 B. C. until the latter
part of the nineteenth century. The pollen data also indicate a step-by-step increase in grazing pressure, expressed as a
marked increase in non-arboreal pollen representation at ca. 1500 B. C., A. D. 650 and A. D. 1650. The increase at A. D. 650
probably indicates a more regular and intensive use of the area, resulting in a forest structure that was much more open than
earlier, together with an expansion of Fagus, which rapidly replaced Quercus as the local forest dominant. At about this time the first patches of heath vegetation originated, but they probably only
covered a small part of Kullaberg. Larger areas with an intensively grazed Calluna heath, as shown by eighteenth century maps, probably evolved around ca. A. D. 1650, when much of Kullaberg seems to have
been deliberately deforested.
Received February 20, 2001 / Accepted September 12, 2001 相似文献
6.
The results of pollen analysis of two sediment cores from lake Srebarna (northeast Bulgaria) are presented. On the basis
of the palynological data and the radiocarbon dates a reconstruction of the past flora and vegetation is made. For the first
time a continuous palaeosuccession is established for the area of the Danubian Dobrudza and the Ludogorie district of northeast
Bulgaria: a dominance of mixed xero- and mesophilous oak woods with Carpinus betulus, Ulmus, Tilia, Corylus during the Atlantic period; mixed oak woods with increasing importance of Tilia, Ulmus, Acer and a considerable presence of Carpinus betulus and Fagus during the Sub-boreal period; degradation of the woodland vegetation and transition to secondary plant communities with Carpinus orientalis and herbs during the Sub-atlantic period.
Received January 5, 2001 / Accepted March 13, 2001 相似文献
7.
The sediment stratigraphy of a medium-sized mixotrophic lake (Ruila) situated below the highest shoreline of the Baltic Ice
Lake in the West-Estonian Lowland is described. The lake is without natural inlets our outlets. The reconstruction of vegetation
and land-use history based on pollen data, combined with available archaeological data and detailed 14C dating allows us to give a provisional reconstruction of the temporal and spatial pattern of natural and human induced environmental
changes in north-west Estonia during the Holocene. Both radiocarbon dates derived from terrestrial macrofossil dating by accelerator
mass spectrometry (AMS) and conventional dating of bulk lake sediment are discussed. The isolation of the lake basin from
the Yoldia Sea took place ca. 9700 cal B. C. The Ancylus Lake transgression at ca. 8400 cal B. C. did not reach the basin,
but caused a ground water rise, seen in the sediment stratigraphy of the lake. The first signs of human impact on the pollen
record appear ca. 5400 cal B. C. (Late Mesolithic). The history of arable farming has been divided into three periods: 1)
introduction of crop cultivation and animal husbandry (1500 cal B. C. – A. D. 500); 2) establishment of animal husbandry A.
D. 500–1000) and 3) establishment of crop cultivation and intensive cattle breeding (A. D. 1000–today). Due to unfavourable
eda-phic conditions the introduction of arable farming was delayed for more than 1000 years compared with elsewhere on the
north coast of Esotnia, and intensity of land-use never reached the same proportion as in these areas.
Received August 15, 2001 / Accepted August 5, 2002
Correspondence to: Leili Saarse 相似文献
8.
Anna Maria Mercuri Carla Alberta Accorsi Marta Bandini Mazzanti 《Vegetation History and Archaeobotany》2002,11(4):263-276
The cores from the Albano and Nemi lakes, near Rome, were studied within the European Union funded PALICLAS project and provided
high resolution records of the Late-glacial and Holocene. Pollen evidence of increasing human influence on vegetation was
recorded in the Holocene parts of both diagrams, and the Cannabis (hemp) curve was one of the major signs. In this paper we present unambiguous pollen evidence from the Cannabaceae records
for the cultivation of hemp in central Italy by the Romans. The oldest records of Cannabis and Humulus (hop) date from to the Late-glacial. Hop pollen values rise during the mid Holocene, while hemp pollen becomes more abundant
from ca. 3000 cal B.P. onwards. The highest earliest hemp peak (21%) is dated to the 1st century A.D. This ‘Cannabis phase’, with the abrupt rise of hemp pollen soon after the rise of cultivated trees (Castanea, Juglans and Olea) is associated with the increase in cereals and ruderal plants. This unambiguous proof of cultivation by Romans around 2000
B.P. occurs as well as a long lasting pre-Roman presence of hemp in the area, which is natural and possibly also anthropogenic.
Subsequent clear episodes of cultivation in the medieval period were found.
Received February 4, 2002 / Accepted September 13, 2002
Correspondence to: Anna Maria Mercuri, e-mail: mercuri.annamaria@unimo.it 相似文献
9.
Mihkel Kangur 《Vegetation History and Archaeobotany》2002,11(4):289-294
Analysis of microscopic charcoal particles is a useful part of palaeoecological research and is mostly used in conjunction
with pollen analysis. However, there is considerable variation in the methodology of charcoal analyses. This paper considers
various methods for the analysis of microscopic charcoal and the presentation of charcoal data in the context of a study of
the upper sediments of two lakes Estonia. The results are evaluated by comparing both the pollen and charcoal data with documentary
evidence of forest fires over the past 60 years. Indications of fires both varying in extent and at different distances from
the lakes are evaluated in both the pollen and charcoal diagrams. The results suggest that the total area curve for charcoal
particles per unit mass of sediment dry matter (cm2 g−1) provides the best indicator of forest fires. Fires in the study area are reflected differently in the charcoal and pollen
curves. It is suggested that the charcoal data have the potential to indicate disturbance at a greater distance from the coring
site than indicated by the pollen data.
Received February 5, 2002 / Accepted August 14, 2002 相似文献
10.
Michael Wille Henry Hooghiemstra Hermann Behling Klaas van der Borg Alvora Jose Negret 《Vegetation History and Archaeobotany》2001,10(2):61-77
We present a reconstruction of forest history and climatic change based on 11 pollen records from eight sites, all located
in the lower montane forest belt of the northern Andes in Colombia. We compared records from the Popayán area in southern
Colobia, Timbio (1750 m), Genagra (1750 m) and Pitalito (1300 m) and the new Piagua (1700 m) record with the records from
Lusitania (1500 m), Libano (1820 m), Pedro Palo (2000 m) and Ubaqué (2000 m) from Central Colombia. The changes of the altitudinal
position of the lower/upper montane (= subandean/Andean, S/At) forest belt transition were used to estimate temperature change
for the last 50 kyr. We infer a Last Glacial Maximum (LGM) temperature drop of 6°–7°C at 1700 m, and a steeper LGM lapse rate
of 0.76°C/100 m compared to today (ca. 0.6°C/100 m). Around 50 uncal. kyr B.P. the temperature at 1700 m was ca. 3°C lower
than today. Until 20 uncal. kyr B.P. the temperature oscillated and gradually decreased. During the LGM, temperature was down
to ca. 6°–7°C lower than today. After the LGM, temperature increased and ca. 14 uncal. kyr B.P. it was 2°–3°C lower than today
(S/At at ca. 1800 m, 500 m below present elevation; Susacá interstadial). An unquantified cooling (Ciega stadial) followed.
During ca. 12.3–11.7 uncal. kyr B.P. the S/At shifted upslope to 2100 m indicating a temperature of 1°–2°C cooler than today
(Guantiva interstadial). From 11.7–10.9 uncal. kyr B.P. the S/At was at 1800 m indicating that the temperature was ca. 3°C
lower than today and wet conditions prevailed (partly coinciding with the El Abra stadial). The period 10.9–9 uncal. kyr B.P.
was also cool, but drier. During 9–7.5 uncal. kyr B.P. temperature was ca. 1°C warmer relative to today (mid Holocene hypsithermal).
During the last 5 kyr the presence of cultivated plants demonstates human colonization of the lower montane zone in Colombia.
Received June 14, 2000 / Accepted December 19, 2000 相似文献
11.
A continuous pollen record covering the last 28 kyr was obtained from core C106 collected in the Bay of Salerno in the southern
Tyrrhenian Basin, seven radiocarbon dates and the recognition of two tephra layers (Y3 and Pompeii Pumice) providing good
chronological constraints. The clear climatic signal given by the pollen spectra integrated by isotopic data, combined with
comparisons with other Mediterranean sites, allowed the Last Glacial, Late Glacial and Holocene periods to be distinguished
in the core. In particular, the Last Glacial period is characterised by large quantities of herbaceous and steppe elements
such as Artemisia. The beginning of the Late Glacial has been correlated with the first increase of deciduous Quercus and the reduction of steppe and herbaceous elements. The Younger Dryas event is recorded only by oxygen isotopes while the
vegetation does not seem to change, as in other Mediterranean sites. The Holocene corresponds to rich deciduous and evergreen
forests. The first features which could be interpreted as signs of human presence are represented by a few grains of Juglans, Castanea and cereal-type while intensive olive cultivation and deforestation seem to fall within the Middle Ages.
Received October 10, 2001 / Accepted June 20, 2002
Correspondence to: Elda Russo Ermolli 相似文献
12.
The influence of pre-industrial animal husbandry on the boreal forest in south-central Sweden has been studied by pollen
and charcoal analyses of peat profiles from two mires in the vicinity of a shieling site. The impact of farming on the local
vegetation development is demonstrated from cal. A. D. 1300–1500 in three ways: forest clearance and cultivation of cereals
at the local shieling site; alterations of hydrology and vegetation, such as an increase in Cyperaceae, at mires used for
hay production; changes in the composition in the surrounding forest, with decreasing proportions of Betula, Picea and boreo-nemoral broadleaved trees and a consequent increase in Pinus, due to grazing and a change of fire regime. Similar alterations to the forest vegetation are noted at other sites in central
and northern Sweden during the last thousand years, when the system of using shielings became more widespread. Hence, early
animal husbandry is demonstrated to have had a regional impact on the long-term boreal forest development, replacing the original
mixed deciduous-coniferous forest with Pinus dominated forest.
Received November 27, 2001 / Accepted June 20, 2002
Correspondence to: Marie Emanuelsson 相似文献
13.
Anne-Marie Lézine Jean-François Saliège Robert Mathieu Thibaut-Louis Tagliatela Sophie Mery Vincent Charpentier Serge Cleuziou 《Vegetation History and Archaeobotany》2002,11(3):221-232
Pollen and micropalaeontological analyses carried out on mangrove swamp sediments of Suwayh, Oman (22°05.589'N, 50°40.033'E)
reveal environmental changes linked both to climate (monsoon) and geomorphological (sea-level) variations during the Late
Holocene. A Rhizophora mangrove developed at Suwayh around 6000 years B. P. under climate conditions marked by an increased tropical influence as
compared to the modern situation, with dominant summer rains. The later extension of Prosopis cineraria at Suwayh provides evidence for a different rainfall pattern, with a winter rainy season. Pollen and micropalaeontological
composition shows three episodes influenced by the sea water at Suwayh. The most important corresponded to the mangrove episode
centred ca 6000 B. P. This was followed by two episodes of slight seawater incursion at ca. 5100 and 4500 B. P. responsible
for the formation of a brackish laagon. Comparison based on 14C measurements on shell recovered from both the sedimentary sequence of Suwayh and the nearby archaeological sites demonstrates
that close relations existed between man and mangroves during the Neolithic and the Early Bronze Age.
Received October 31, 2001 / Accepted January 24, 2002
Correspondence to: Anne-Marie Lézine 相似文献
14.
Pollen, microscopic charcoal and peat humification analyses were applied to radiocarbon-dated peat cores to examine environmental
change before and after the mid-Holocene transition from hunter-gatherer (Mesolithic) to agricultural (Neolithic) communities
in presently marginal upland pasture at Stanshiel Rig, Annandale, southern Scotland. The Mesolithic-Neolithic transition in
northern Britain is characterised by a number kf key environmental changes as well as economic shifts, including temporal
patterns of fire and the Ulmus decline. Deliberate vegetation modification by Mesolithic communities is not demonstrable at Stanshiel Rig, and openings
in the woodland canopy may have been promoted by grazing by wild animals or have been a consequence of climate change. Changes
in fire frequency are also correlated with peat- and pollen-stratigraphic evidence for shifts to a drier climate in the late
Mesolithic, probably mediated through pedological and biomass-storage change. A single Ulmus decline occurred between ca. 5650 and 5600 cal B. P., and is related here to climate change. Neolithic-age impacts on the
woodland were limited, and no cereal-type pollen were found. The difference between hunter-gatherer and opportunistic farmer/hunter-gatherer
at this locally is argued to be insignificant, or not detectable palynologically.
Received October 4, 2001 / Accepted July 22, 2002
Correspondence to: S. M. Cayless 相似文献
15.
Helena Svobodová Maurice Reille Claude Goeury 《Vegetation History and Archaeobotany》2001,10(4):185-199
Six pollen diagrams from peat bogs in the Vltavsky luh (upper Vltava river valley) provide new information about vegetation
reconstruction, woodland dynamics, and local development of mires during the Late-glacial and Holocene. Vegetation development
began in the Oldest Dryas/B?ling with open park plant cover. In the Aller?d, woodland with Pinus and Betula developed, and in the Younger Dryas there was a steppe tundra with plants of open habitats. In the Pre-boreal, woodland tundra
grew. In the Boreal, Corylus spread, and a major expansion of Picea began in the early Boreal. Picea spread during the Atlantic probably by two different migration routes. Fagus immigrated earlier than in the Bayerischer Wald and Oberpf?lzer Wald in the adjoining parts of Germany, and had its major
expansion in the early Atlantic. Abies expanded in the late Atlantic. The great abundance of Abies in this area is remarkable, forming Abies or Abies-Fagus woods in less extreme habitats. Human occupation started in the Sub-boreal, as shown by both archaeology and palynology.
However, human impact is recognized from anthropogenic indicators which appear in the early Atlantic. At the end of the later
Sub-atlantic the development of natural woodland was interrupted by plantation of Picea according to historical and palynological evidence.
Received November 13, 2000 / Accepted July 7, 2001 相似文献
16.
Summary. The accumulation of oxidized proteins is known to be linked to some severe neurodegenerative diseases like Alzheimer’s, Parkinson’s
and Huntington’s disease. Furthermore, the aging process is also accompanied by an ongoing aggregation of misfolded and damaged
proteins. Therefore, mammalian cells have developed potent degradation systems, which selectively degrade damaged and misfolded
proteins. The proteasomal system is largely responsible for the removal of oxidatively damaged proteins form the cellular
environment. Not only cytosolic proteins are prone to oxidative stress, also nuclear proteins are readily oxidized. The nuclear
proteasomal system is responsible for the degradation of these proteins. This review is focused on the specific degradation
of oxidized nuclear proteins, the role of the proteasome in this process and the regulation of the nuclear proteasomal system
under oxidative conditions. 相似文献
17.
Density-dependent pollen germination and tube growth in vitro is a well-documented phenomenon, termed the pollen population
effect, but far less is known about its molecular basis. We present evidence to support phytosulfokine-α [Y(SO3H)IY(SO3H)TQ; PSK-α] as a native bioactive factor contributing to this effect. Mature pollen grains of Nicotiana tabacum L. var.macrophylla were incubated in liquid medium for 2 h. Pollen germination frequency increased in a density-dependent manner from 625 to
46,000 grains/ml. Conditioned medium, obtained from the medium of pollen cultured at a density of 10,000 pollen grains/ml
for 12 h, promoted the germination of pollen cultured at a low density (625 grains/ml). A rabbit antiserum against PSK-α specifically
inhibited the promotive effect of conditioned medium. Quantification by enzyme-linked immunosorbent assay showed that the
conditioned medium contained 0.4 nM of PSK-α. Exogenous PSK-α also stimulated pollen germination in the low-density culture.
These results indicate that PSK-α is an important regulator involved in the pollen population effect.
Received: 15 March 2000 / Accepted: 24 May 2000 相似文献
18.
Monoclonal antibodies that recognize pectins were used for the localization of esterified (JIM7) and acidic, unesterified
(JIM5) forms of pectin in pollen tube walls of Ornithogalum virens L. (x = n = 3). The results indicated that the distribution of the two forms of pectin in the pollen tube wall depended on
the medium (liquid or solid) used for pollen germination. In pollen tubes grown in the liquid medium, the localization of
JIM7 was limited to the very tip of the pollen tube, whereas the localization of JIM5 indicated a uniform distribution of
unesterified pectins in the very tip of the tube and along the subapical parts of the tube wall. In tubes germinated on the
medium stabilized with agar (1–2%) the localization of JIM7 and JIM5 indicated the presence of both forms of pectin in the
tube tip and along the whole length of the pollen tube wall in a ring-like pattern. Thus, the localization of esterified pectins
in the sub-apical part of the pollen tube wall, below the apex of the tube, is described for the first time. Measurements
of the growth rates of pollen tubes growing on the two types of medium indicated that oscillations in tube growth rate occur
but these do not coincide with the pattern of pectin distribution in the tube wall. Our results complement the previous data
obtained for the localization of JIM5 and JIM7 in pollen tube walls of other plant species. (Y.-Q. Li et al. 1994, Sex Plant
Reprod 7: 145–150) and provide new insight into an understanding of the construction of the pollen tube wall and the physiology
of pollen grain germination.
Received: 25 January 1999 / Accepted: 23 June 1999 相似文献
19.
At the end of the 6th millennium B. C. Triticum monococcum (einkorn) and Triticum dicoccum (emmer) were the main cereals of the early Neolithic Bandkeramik culture in central Europe. New archaeobotanical investigations
at relevant Bandkeramik sites reveal the regular occurrence of morphologically two-grained einkorn. Some preliminary thoughts
on the state of research and the possible origin of two-grained einkorn forms are presented here.
Received January 7, 2002 / Accepted August 5, 2002
Correspondence to: Angela Kreuz 相似文献
20.
Juan Carlos Berrío Arnoud Boom Pedro José Botero Luisa Fernanda Herrera Henry Hooghiemstra Freddy Romero Gustavo Sarmiento 《Vegetation History and Archaeobotany》2001,10(3):161-174
An environmental reconstruction of the last 10,000 14C years of a frequently flooded wetland ecosystem in the lower Magdalena valley in northern Colombia is presented, on the
basis of a multi-disciplinary study of the sediments of the upper 15 m of the core from Boquillas (74°33'E, 9°7'N; 20 m a.
s. l.). We used the following studies: pollen, lithology, organic structures, clay mineralogy, soil and sediment geochemistry,
and δ13C values. The chronology is based on 13 AMS radiocarbon dates; the humic acid fractions were used in the case of seven samples.
Pollen from local origin (swamps, open grass-rich vegetation, and gallery forest) show the development of the wetland area.
River-transported pollen from a greater distance (dry forest, montane forest, Alnus) show changes in river activity and reflect large-scale changes of climatic conditions in the Momposina basin. From c. 10,010
to 9370 uncal B. P. (zone BQS-Ia) the river system was of high energy, as inferred by the lithological changes. The landscape
was dominated by open grass-rich vegetation with gallery forest along the streams. A marked representation of Alnus and montane forest taxa indicate significant water transport and river dynamics. Climatic conditions were dry. From c. 9370-8430
uncal B. P. (zone BQS-Ib) wetlands were isolated from the main river system, and clayey sediments with kaolinite, smectite
and illite as the main minerals accumulated in a lower-energy environment. Climatic conditions were dry and changes in the
seasonal precipitation favoured the expansion of the gallery forest. From c. 8430 to 8040 uncal B. P. (zone BQS-Ic) low values
of river-transported pollen indicate dry climatic conditions and open vegetation became more abundant. The flooding frequency
of the Boquillas site diminished. From 8040 to 4900 uncal B. P. (zone BQS-Id) the Boquillas site was dominated by open vegetation
with patches of gallery forest along the streams. Supply of river-transported allochthonous pollen (from many sources) was
minimal. Clay minerals from the sediments suggest variable temperature and precipitation. From c. 4900 to 1550 uncal B. P.
)zone BQS-II) the site was within the reach of the main river system as is the case today. Frequent flooding, coinciding with
peaks of river-transported grains of Alnus and high sediment supply, point to high precipitation in the composite catchment area of the Magdalena, Cauca, San Jorge,
and Cesár rivers. High values of phosphorous in the upper part of the core point to the presence of a pre-Hispanic civilization,
approximately from 2000 uncal B. P. onward. Construction of an extensive drainage system allowed irrigation as well as drainage
depending the annual cycle of precipitation. The landscape was significantly modified and allowed an extensive crop production
on a system of raised fields.
Received May 18, 2001 / Accepted June 15, 2001 相似文献