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1.
Palynological data on major Holocene climatic events in NW Iberia   总被引：6，自引：0，他引：6  
Three NW Iberia Cantabrian Mountain pollen records are presented. They reflect the main Holocene climatic shifts in the North Atlantic region as recorded in the isotopic data from Greenland ice, Irish speleothems and reconstructed sea surface temperatures. Two brief forest regression episodes reconstructed from pollen may be synchronous with GH-11.2 and GH-8.2 events. At mid-altitude, two woodland expansion phases (7000-6000 14C yr BP and 4000-2500 14C yr BP) are separated by a phase of heaths and peat deposits. Major woodland declines occurred during the Galician-Roman Period (which includes the Bronze Age, the Iron Age and the Roman occupation) and from the end of the Medieval Period. The pollen data, backed up by archaeological and historical sources, suggest climatic impact of the Iron Age Cold Period, but are indecisive concerning the Little Ice Age. However, the pollen records do not support any significant 'Neoglacial' period (4000-3000 14C yr BP) influence on NW Iberia.  相似文献   

2.
《Quaternary Science Reviews》2007,26(11-12):1476-1498
Palynological and sedimentological studies were performed at two Holocene profiles in erosion gullies (Ze’elim and Ein Feshkha) which dissect the retreating western shore of the Dead Sea. The aim of the project was to analyse possible links between climate, lithology, and vegetation development. The section in Ze’elim shows both lacustrine and fluvial sediments, whereas sedimentation at Ein Feshkha is predominantly lacustrine. The Ze’elim profile, previously used for paleo-lake reconstruction provides an opportunity to compare climate triggered lake levels as paleo-hydrological indicators and vegetation history by use of palynology. The vegetation development in Ze’elim and Ein Feshkha is influenced by both climate and human impact. The pollen record of Ze’elim begins in the Pottery Neolithic, the section of Ein Feshkha in the Late Bronze Age, both records end in the Middle Ages. The Ze’elim section is characterized by sedimentary hiati between the beginning of the Chalcolithic Period until the Middle Bronze Age and within the Late Bronze Age. Settlement periods during the Middle Bronze Age, Iron Age and Hellenistic–Roman–Byzantine Period are indicated by high values of anthropogenic indicators and/or Mediterranean trees. Collapses of agriculture, which can be related to climate effects, are evident during the Late Bronze Age, during the Iron Age and at the end of the Byzantine Period when the lake level curve indicates arid conditions. A comparison of the two pollen records, from different environments, illustrates a more prominent influence of Mediterranean vegetation and cultivated plants in the pollen diagram of Ein Feshkha. The southern Dead Sea region (at the desert fringe) is more vulnerable to regional climate change.  相似文献   

3.
The comparison of pollen diagrams and their inferred vegetational histories are an important component of palaeoecological research. Radiocarbon-dated pollen profiles from three cores taken from two adjacent mires located in northern Cumbria, Bolton Fell Moss and Walton Moss, have been used to reconstruct the Late Holocene vegetation history between the Bronze Age and the present day. The profiles have been interpreted in the light of available archaeological and historical records and, although the pollen records are broadly similar, there are some notable differences between them, particularly during Iron Age and medieval times. Dissimilarities between the diagrams are explored numerically, and the statistical and palynological results are discussed in relation to pollen representativity. The results suggest that it may be advantageous to construct more than one pollen diagram from a mire, or even adjacent mires, as extra-local pollen may be a more important part of the pollen rain than previously envisaged. © 1998 John Wiley & Sons, Ltd.  相似文献   

4.
The Holocene sediment of Lago Piccolo di Avigliana (Piedmont, Italy, 356 m a.s.l.) was dated by 14C and analysed for pollen to reconstruct the vegetation history of the area. The early‐ and mid‐Holocene pollen record shows environmental responses to centennial‐scale climatic changes as evidenced by independent palaeoclimatic proxies. When human impact was low or negligible, continental mixed‐oak forests decreased at ca. 9300 BC in response to the early‐Holocene Preboreal climatic oscillation. Abies alba expanded in two phases, probably in response to higher moisture availability at ca. 6000 and ca. 4000 BC , while Fagus expanded later, possibly in response to a climatic change at 3300 BC . During and after the Bronze Age five distinct phases of intensified land use were detected. The near synchroneity with the land‐use phases detected in wetter regions in northern and southern Switzerland points to a common forcing factor in spite of cultural differences. Increasing minerogenic input to the lake since 1000 BC coincided with Late Bronze—Iron Age technical innovations and probably indicate soil erosion as a consequence of deforestation in the lake catchment. The highest values for cultural indicators occurred at 700–450 and at 300–50 BC , coinciding with periods of high solar activity (inferred from Δ14C). This suggests that Iron Age land use was enhanced by high solar activity, while re‐occupation of partly abandoned areas after crises in earlier periods match better with the GRIP stable isotope record. On the basis of our data and comparison with independent palaeoclimatic proxies we suggest that precipitation variation was much more important than temperature oscillations in driving vegetation and societal changes throughout the Holocene. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

5.
The Ural Mountains are an important climatic and biogeographical barrier between European and Siberian forests. In order to shed light on the postglacial formation and evolution of the boreal forests in the European pre-Urals, we obtained a peat sediment core, Chernaya, from the Paltinskoe bog located between the southern taiga and hemiboreal forest zone in the mid-Kama region. We carried out pollen analysis, non-pollen palynomorph analysis, loss-on-ignition tests and radiocarbon dating. Radiocarbon dated records provide centennial to decennial resolution of the vegetation and environmental history of the European pre-Urals for the last 8.8 ka. The postglacial formation of the pre-Uralian hemiboreal forests reveals four important phases: (i) the dominance of Siberian taiga and forest-steppe in the Early Holocene and beginning of the Middle Holocene (8.8–6.9 ka), indicating a dry climate; (ii) the spread of spruce and European broadleaved trees in the Middle Holocene (6.9–4 ka) under wetter climate conditions; (iii) the maximum extent of broadleaved trees coinciding with the arrival and spread of Siberian fir in the Late Holocene (4–2.3 ka); and (iv) the decline of broadleaved trees since the Early Iron Age (2.3 ka – present) possibly due to general climate cooling and logging. While temperate broadleaved trees possibly spread from local refugia in the Urals, fir arrived from Siberia and spread further west. The carbon accumulation rate of Paltinskoe bog (18.9±10.16 g C m−2 a−1) is close to the average value of carbon accumulation of northern peatlands. Local development of peat is characterized by non-gradual growth with a phase of intensive carbon accumulation between 3.5 and 2.3 ka. The vegetation was strongly influenced by fire in the Early Holocene and by humans since the Early Iron Age practicing deforestation, agriculture and pasture. Phases of increased anthropogenic activity correlate well with the local archaeological data.  相似文献   

6.
Kosipe, an upland valley at 2000 m altitude in the Owen Stanley Ranges of southeastern New Guinea, is known for the discovery of large stone waisted blades dated to 31 400 cal a BP. The purpose of these tools and the nature of occupation are unknown. The altitude is too high for most food crops today and may have stood close to the treeline during the last glaciation. Three pollen and charcoal diagrams from a large swamp in the Kosipe Valley provide a record of swamp and dryland changes for more than 50 000 years. There have been considerable fluctuations in vegetation on the slopes and on the swamp which reflect both environmental change and anthropogenic influences. A gymnosperm-rich forest at the base is replaced by mountain forest dominated by Nothofagus about 42 000 years ago. Fire first becomes apparent across the swamp around 40 000 years ago but is not common during the time when subalpine herbs reach their best representation. Tree fern-rich grasslands form a mosaic with montane forest in a near-treeline environment. The Pleistocene–Holocene boundary is marked by a decline in Nothofagus and increase in lower montane mixed forest taxa. Charcoal increases before this time and the swamp vegetation becomes more grass-rich. Charcoal is at its maximum through the last 3000 years possibly reflecting climate variability as well as sedentary occupation and agriculture on the swamp margin. Supplementary pollen diagrams from two higher altitude sites support the evidence from the Kosipe Swamp cores. Charcoal, local catchment erosion and increases in disturbance taxa become more widespread in the last 5000 years at these sites, suggesting that local settlement at Kosipe may have lagged behind general landscape use by populations from lower altitudes.  相似文献   

7.
《Quaternary Science Reviews》1999,18(4-5):711-716
Charcoal analysis of three archaeological sites in southern Syria in the vicinity of the Jebel al Arab (formerly Jebel Druze) indicates that during the Early Bronze Age an association consisting predominately of Pistacia, deciduous oak and almond was exploited. During the Middle Bronze Age these taxa diminish and are partially replaced by more steppic species or introduced wood such as olive. During the Roman period evergreen oak appeared in the region and gradually replaced the deciduous oak which is now restricted to a small area. The gradual replacement of deciduous oaks by evergreen oaks has been observed in other areas of the Mediterranean basin during the Holocene. Conifer charcoal such as pine and cedar is present on the sites, but it is not clear whether these were local or imported from farther away, for example, the Lebanese highlands. During the Middle Bronze Age olive wood was also used as combustible but here also its exact origin is not known.  相似文献   

8.
We reconstructed a 10,500-yr fire and vegetation history of a montane site in the North Cascade Range, Washington State based on lake sediment charcoal, macrofossil and pollen records. High-resolution sampling and abundant macrofossils made it possible to analyze relationships between fire and vegetation. During the early Holocene (> 10,500 to ca. 8000 cal yr BP) forests were subalpine woodlands dominated by Pinus contorta. Around 8000 cal yr BP, P. contorta sharply declined in the macrofossil record. Shade tolerant, mesic species first appeared ca. 4500 cal yr BP. Cupressus nootkatensis appeared most recently at 2000 cal yr BP. Fire frequency varies throughout the record, with significantly shorter mean fire return intervals in the early Holocene than the mid and late Holocene. Charcoal peaks are significantly correlated with an initial increase in macrofossil accumulation rates followed by a decrease, likely corresponding to tree mortality following fire. Climate appears to be a key driver in vegetation and fire regimes over millennial time scales. Fire and other disturbances altered forest vegetation at shorter time scales, and vegetation may have mediated local fire regimes. For example, dominance of P. contorta in the early Holocene forests may have been reinforced by its susceptibility to frequent, stand-replacing fire events.  相似文献   

9.
The significance of geoarchaeological investigations is indisputable in reconstructing the former environment and in studying the relationship between humans and their surroundings. Several disciplines have developed during the last few decades to give insight into earlier time periods and their climatic conditions (e.g. palynology, malacology, archaeobotany, phytology and animal osteology). Charcoal and pollen analytical studies from the rescue excavation of the MO motorway provide information about the vegetation changes of the past. These methods are used to reconstruct the environment of the former settlements and to detect the human impact and natural climatic changes. The sites examined span the periods of the Late-Copper Age, Late-Bronze Age, Middle-Iron Age, Late-Iron Age, Sarmatian period, Late Sarmatian period, Migration period, Late-Migration period and Middle Ages. The vegetation before the Copper Age is based only on pollen analytical data. Anthracological results show the overall dominance of Quercus and a great number of Ulmus, Fraxinus, Acer, Fagus, Alnus and Populus/Salix tree fossils, as well as the residues of fruit trees present in the charred wood assemblage.  相似文献   

10.
Palaeoenvironmental research is playing an important role in recent archaeological investigations. We present preliminary results of geoarchaeological analyses conducted at a palaeochannel located between two prehistoric archaeological sites in eastern Hungary. The study area lies within the Körös River Basin in Békés County, a region of intensive human occupation beginning in the Neolithic, ca. 7550 BP, and represents only the second palynological analysis done in conjunction with archaeological investigations and adjacent to an archaeological site in the Körös region. Pollen from an environmental monolith was used to reconstruct the local vegetation composition and the human impact on arboreal and non-arboreal vegetation near the archaeological sites. Sediment analyses helped to reconstruct hydrological activity and human impact on the local palaeochannel. Results indicate that activity from the Neolithic onwards played an important role in local environmental change, including increasing sedimentation and deposition of organic matter in the local waterway, some forest clearance and a shift from primarily arboreal vegetation to more grasses on elevated surfaces. The trophic status of the local channel changed several times during the Holocene. In addition, indications that groundwater levels may have been fluctuating during the period of human occupation, when combined with the other changes in the area, provide a possible partial explanation for changing settlement patterns.  相似文献   

11.
This paper describes a multi‐proxy palaeoecological investigation undertaken in conjunction with an archaeological survey of the Upper Sangro Valley in the Abruzzo National Park, Central Italy. Despite being a biodiversity hotspot and regarded as a near‐pristine area, the pollen, spore and diatom data all show major changes in the vegetation extending to over 2000 m a.s.l. during the mid to late Holocene. Although there are changes in ecological composition earlier in the Holocene they are different in type and magnitude from the changes which began about 800 cal a BC. The pollen and diatom evidence do not correlate well with regional palaeoclimate data, or on‐site isotopic evidence, but do appear to be related to Samnite (later Iron Age) clearance and upland grazing associated with transhumance and later annexation (and centuriation) of the lower slopes by Roman surveyors. The greatest change in vegetation was during the period c. AD 500–600 and corresponds with the Byzantine–Gothic Wars, and Lombard–Carolingian settlement reorganization into nucleated hilltop settlements which managed upland grazing. This pattern of intensive land use at all altitudes persisted until the early 20th century and only changed following rural depopulation after World War II. These data illustrate how cultural factors had a profound effect on this mountainous region which, in this case, far outweighed the effects of climatic fluctuations which are known to have occurred from both this study area and the region. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

12.
The Holocene fire regime is thought to have had a key role in deforestation and shrubland expansion in Galicia (NW Spain) but the contribution of past societies to vegetation burning remains poorly understood. This may be, in part, due to the fact that detailed fire records from areas in close proximity to archaeological sites are scarce. To fill this gap, we performed charcoal analysis in five colluvial soils from an archaeological area (Campo Lameiro) and compared the results to earlier studies from this area and palaeo-ecological literature from NW Spain. This analysis allowed for the reconstruction of the vegetation and fire dynamics in the area during the last ca 11 000 yrs. In the Early Holocene, Fabaceae and Betula sp. were dominant in the charcoal record. Quercus sp. started to replace these species around 10 000 cal BP, forming a deciduous forest that prevailed during the Holocene Thermal Maximum until ～5500 cal BP. Following that, several cycles of potentially fire-induced forest regression with subsequent incomplete recovery eventually led to the formation of an open landscape dominated by shrubs (Erica sp. and Fabaceae). Major episodes of forest regression were (1) ～5500–5000 cal BP, which marks the mid-Holocene cooling after the Holocene Thermal Maximum, but also the period during which agropastoral activities in NW Spain became widespread, and (2) ～2000–1500 cal BP, which corresponds roughly to the end of the Roman Warm Period and the transition from the Roman to the Germanic period. The low degree of chronological precision, which is inherent in fire history reconstructions from colluvial soils, made it impossible to distinguish climatic from human-induced fires. Nonetheless, the abundance of synanthropic pollen indicators (e.g. Plantago lanceolata and Urtica dioica) since at least ～6000 cal BP strongly suggests that humans used fire to generate and maintain pasture.  相似文献   

13.
Pollen analyses of three sediment cores performed on the archaeological lake dwellings of Chindrieux and Tresserve (Savoie, France), on the eastern shore of Lake Bourget, enable the reconstruction of vegetation history and human impact during the Bronze Age. Results show a good correlation between lake-level fluctuations and the evolution of anthropogenic indicators. The end of the Neolithic period and the early Bronze Age are characterised by a discreet occupation of the Lake Bourget surroundings, in spite of a warmer climatic condition. The middle Bronze Age, contemporaneous with wetter and cooler conditions, is related to a decrease in pollen of cultivated plants and weed. Farming activities reappear in the late Bronze Age and human impact increases suddenly at the very end of the late Bronze Age. Three anthropogenic phases are clearly visible: a short decrease in anthropogenic indicators and a high lake-level phase occur in the middle of this period of intense farming development. A new decrease in human impact appears at the beginning of the Iron Age.  相似文献   

14.
Pollen, chironomid, and ostracode records from a lake located at alpine treeline provide regional paleoclimate reconstructions from the southwest Yukon Territory, Canada. The pollen spectra indicate herbaceous tundra existed on the landscape from 13.6–11 ka followed by birch shrub tundra until 10 ka. Although Picea pollen dominated the assemblages after 10 ka, low pollen accumulation rates and Picea percentages indicate minimal treeline movement through the Holocene. Chironomid accumulation rates provide evidence of millennial-scale climate variability, and the chironomid community responded to rapid climate changes. Ostracodes were found in the late glacial and early Holocene, but disappeared due to chemical changes of the lake associated with changes in vegetation on the landscape. Inferred mean July air temperature, total annual precipitation, and water depth indicate a long-term cooling with increasing moisture from the late glacial through the Holocene. During the Younger Dryas (12.9–11.2 ka), cold and dry conditions prevailed. The early and mid-Holocene were warm and dry, with cool, wet conditions after 4 ka, and warm, dry conditions since the end of the Little Ice Age.  相似文献   

15.
A high-resolution pollen record from Path Lake in Port Joli Harbour, Nova Scotia, Canada, provides a paleo-ecological perspective on Holocene climate and vegetation variability within the context of local archaeological research. Pollen assemblages in the early Holocene reflect a post-glacial forest dominated by Pinus, Tsuga, Betula and Quercus. During this time, a lower frequency of radiocarbon dated cultural material suggests lower human settlement intensity. Shallow water aquatic (Isoetes) and wetland (Alnus, Sphagnum) taxa increased after 3400 cal yr BP in response to a transition towards wetter climatic conditions. Culturally significant periods, where settlement intensity increased in the Maritimes and Maine, coincide with maximum values of reconstructed total annual precipitation, suggesting that environmental conditions may have influenced prehistoric human activity. European settlement, after 350 cal yr BP, was marked by a rise in Ambrosia. The impact of anthropogenic fire disturbances on the landscape was evidenced by peak charcoal accumulations after European settlement.  相似文献   

16.
The microscopic charcoal content of several Quaternary pollen sequences is used to investigate fire history in South Africa both during the Holocene and the Late Pleistocene. Although fluctuations in charcoal composition are recorded, it is difficult to link them directly to either human‐made or natural fires. Strong long‐term variations in microscopic charcoal of Middle and Upper Pleistocene layers are independent of pollen indications of past temperature and moisture conditions. Holocene charcoal sequences from different areas show no correlation, so no phases of regional burning are found. Some fluctuations in charcoal probably are the result of local burning in the various regions. The arrival of Iron Age people some 2000 yr ago apparently did not coincide with widespread wild fires, as these events do not consistently appear in regional microscopic charcoal records. The only exception appears to be the Wonderkrater spring deposit. Relatively open savanna environments, which are implied by pollen analysis at some sites during this period and the generally low microscopic charcoal contents, were either caused by climate change or controlled burning by Iron Age people. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

17.
The aim of this paper is to reconstruct the variation in the vegetation during the Holocene on the Northern Meseta through pollen analysis in order to determine the roles played by Pinus and Quercus in the vegetation dynamics. A new pollen sequence, Camporredondo, in the centre of the Duero River basin, Northern Meseta, Spain, is presented. It covers the period from ca 11,250 to 1630 cal yr BP. The Camporredondo sequence suggests that a forested landscape existed from the start of the Holocene with values of approximately 90% of arboreal pollen mainly derived from pine forests in the surroundings. Shortly after 8600 cal yr BP pine forests continued to dominate but the landscape became more open while stands of deciduous and evergreen Quercus developed. Around 4500 years ago, coinciding with the start of a period of less rainfall, the lacustrine areas in these territories began to silt up, favouring hydrophytic taxa such as Salix or Cyperaceae. A comparison with other Holocene pollen sequences from the central-eastern part of the Northern Meseta confirms the presence of pine forests in the whole region since the early Holocene. We discuss the variations of the general vegetation pattern in terms of the local or regional conditions at each site. Throughout the Holocene, Pinus forests dominated at least in the eastern half of the Duero River basin. The typical Holocene substitution of conifers by broadleaf species as recorded in other parts of the Iberian Peninsula and Europe, never takes place in the study area. The results of the present study suggest that the current view of the potential vegetation in the Spanish Northern Meseta should be reviewed.  相似文献   

18.
《Quaternary Science Reviews》2003,22(5-7):453-473
Lateglacial and early Holocene (ca 14–9000 14C yr BP; 15–10,000 cal yr BP) pollen records are used to make vegetation and climate reconstructions that are the basis for inferring mechanisms of past climate change and for validating palaeoclimate model simulations. Therefore, it is important that reconstructions from pollen data are realistic and reliable. Two examples of the need for independent validation of pollen interpretations are considered here. First, Lateglacial-interstadial Betula pollen records in northern Scotland and western Norway have been interpreted frequently as reflecting the presence of tree-birch that has strongly influenced the resulting climate reconstructions. However, no associated tree-birch macrofossils have been found so far, and the local dwarf-shrub or open vegetation reconstructed from macrofossil evidence indicates climates too cold for tree-birch establishment. The low local pollen production resulted in the misleadingly high percentage representation of long-distance tree-birch pollen. Second, in the Minnesotan Lateglacial Picea zone, low pollen percentages from thermophilous deciduous trees could derive either from local occurrences of the tree taxa in the Picea/Larix forest or from long-distance dispersal from areas further south. The regionally consistent occurrence of low pollen percentages, even in sites with local tundra vegetation, and the lack of any corresponding macrofossil records support the hypothesis that the trees were not locally present. Macrofossils in the Picea zone represent tundra vegetation or Picea/Larix forest associated with typically boreal taxa, suggesting it was too cold for most thermophilous deciduous trees to grow. Any long-distance tree pollen is not masked by the low pollen production of tundra and Picea and Larix and therefore it is registered relatively strongly in the percentage pollen spectra.Many Lateglacial pollen assemblages have no recognisable modern analogues and contain high representations of well-dispersed ‘indicator’ taxa such as Betula or Artemisia. The spectra could have been derived from vegetation types that do not occur today, perhaps responding to the different climate that resulted from the different balance of climate forcing functions then. However, the available contemporaneous plant-macrofossil assemblages can be readily interpreted in terms of modern vegetation communities, suggesting that the pollen assemblages could have been influenced by mixing of locally produced pollen with long-distance pollen from remote vegetation types that are then over-represented in situations with low local pollen production. In such situations, it is important to validate the climate reconstructions made from the pollen data with a macrofossil record.  相似文献   

19.
Pollen and macrofossil analyses of a core spanning 26,000 yr from Davis Lake reveal late Pleistocene and Holocene vegetational patterns in the Puget Lowland. The core ranges lithologically from a basal inorganic clay to a detritus gyttja to an upper fibrous peat and includes eight tephra units. The late Pleistocene pollen sequence records two intervals of tundra-parkland vegetation. The earlier of these has high percentages of Picea, Gramineae, and Artemisia pollen and represents the vegetation during the Evans Creek Stade (Fraser Glaciation) (ca. 25,000–17,000 yr B.P.). The later parkland interval is dominated by Picea, Tsuga mertensiana, and Gramineae. It corresponds to the maximum ice advance in the Puget Lowland during the Vashon Stade (Fraser Glaciation) (ca. 14,000 yr B.P.). An increase in Pinus ontorta pollen between the two tundra-parkland intervals suggests a temporary rise in treeline during an unnamed interstade. After 13,500 yr B.P., a mixed woodland of subalpine and lowland conifers grew at Davis Lake during a period of rapid climatic amelioration. In the early Holocene, the prolonged expansion of Pseudotsuga and Alnus woodland suggests dry, temperate conditions similar to those of present rainshadow sites in the Puget Lowland. More-mesic forests of Tsuga eterophylla, Thuja plicata, and Pseudotsuga, similar to present lowland vegetation, appeared in the late Holocene (ca. 5500 yr B.P.).  相似文献   

20.
An 8400 cal yr record of vegetation change from the northern Peten, Guatemala, provides new insights into the environmental history of the archaeological area known as the Mirador Basin. Pollen, loss on ignition, and magnetic susceptibility analyses indicate warm and humid conditions in the early to mid-Holocene. Evidence for a decrease in forest cover around 4600 cal yr B.P. coincides with the first appearance of Zea mays pollen, suggesting that human activity was responsible. The period between 3450 cal yr B.P. and 1000 cal yr B.P. is characterized by a further decline in forest pollen types, includes an abrupt increase in weedy taxa, and exhibits the highest magnetic susceptibility values since the early Holocene, all of which suggest further agricultural disturbance in the watershed. A brief drop in disturbance indicators around 1800 cal yr B.P. may represent the Preclassic abandonment of the area. Changing pollen frequencies around 1000 cal yr B.P. indicate a cessation of human disturbance, which represents the Late Classic collapse of the southern Maya lowlands.  相似文献   

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