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Bennett, Keith D.
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Publications (10 of 25) Show all publications
Bennett, K. D. (2015). Comment on "Sedimentary DNA from a submerged site reveals wheat in the British Isles 8000 years ago". Science, 349(6245)
Open this publication in new window or tab >>Comment on "Sedimentary DNA from a submerged site reveals wheat in the British Isles 8000 years ago"
2015 (English)In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 349, no 6245Article in journal, Editorial material (Other academic) Published
Abstract [en]

Smith et al. (Reports, 27 February 2015, p. 998) identify wheat DNA from an 8000-calendar-years-before-the-present archaeological site in southern England and conclude that wheat was traded to Britain 2000 years before the arrival of agriculture. The DNA samples are not dated, either directly or from circumstantial evidence, so there is no chronological evidence to support the claim.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-261125 (URN)10.1126/science.aab1886 (DOI)000358218600034 ()
Available from: 2015-08-31 Created: 2015-08-31 Last updated: 2017-12-04Bibliographically approved
Andren, E., Klimaschewski, A., Self, A. E., Amour, N. S., Andreev, A. A., Bennett, K. D., . . . Harnmarlund, D. (2015). Holocene climate and environmental change in north-eastern Kamchatka (Russian Far East), inferred from a multi-proxy study of lake sediments. Global and Planetary Change, 134, 41-54
Open this publication in new window or tab >>Holocene climate and environmental change in north-eastern Kamchatka (Russian Far East), inferred from a multi-proxy study of lake sediments
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2015 (English)In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 134, p. 41-54Article in journal (Refereed) Published
Abstract [en]

A sediment record from a small lake in the north-eastern part of the Kamchatka Peninsula has been investigated in a multi-proxy study to gain knowledge of Holocene climatic and environmental change. Pollen, diatoms, chironomids and selected geochemical parameters were analysed and the sediment record was dated with radiocarbon. The study shows Holocene changes in the terrestrial vegetation as well as responses of the lake ecosystern to catchment maturity and multiple stressors, such as climate change and volcanic eruptions. Climate change is the major driving force resulting in the recorded environmental changes in the lake, although recurrent tephra deposition events also contributed. The sediment record has an age at the base of about 10,000 cal yrs BP, and during the first 400 years the climate was cold and the lake exhibited extensive ice-cover during winter and relatively low primary production. Soils in the catchment were poor with shrub alder and birches dominating the vegetation surrounding the lake. At about 9600-8900 cal yrs BP the climate was cold and moist, and strong seasonal wind stress resulted in reduced ice-cover and increased primary production. After ca. 8900 cal yrs BP the forest density increased around the lake, runoff decreased in a generally drier climate resulting in decreased primary production in the lake until ca. 7000 cal yrs BP. This generally dry climate was interrupted by a brief climatic perturbation, possibly attributed to the 8.2 ka event, indicating increasingly windy conditions with thick snow cover, reduced ice-cover and slightly elevated primary production in the lake. The diatom record shows maximum thermal stratification at ca. 6300-5800 cal yrs BP and indicates together with the geochemical proxies a dry and slightly warmer climate resulting in a high productive lake. The most remarkably change in the catchment vegetation occurred at ca. 4200 cal yrs BP in the form of a conspicuous increase in Siberian dwarf pine (Pinus pumila), indicating a shift to a cooler climate with a thicker and more long-lasting snow cover. This vegetational change was accompanied by marked shifts in the diatom and chironomid stratigraphies, which are also indicative of colder climate and more extensive ice-cover.

Keyword
Pollen, Diatoms, Chironomids, Geochemistry, Climate change, Tephras
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-270627 (URN)10.1016/j.gloplacha.2015.02.013 (DOI)000365369900005 ()
Funder
Swedish Research Council, 621-2004-5224Swedish Research Council, 621-2005-4444
Available from: 2016-01-01 Created: 2016-01-01 Last updated: 2017-12-01Bibliographically approved
Klimaschewski, A., Barnekow, L., Bennett, K. D., Andreev, A. A., Andren, E., Bobrov, A. A. & Hammarlund, D. (2015). Holocene environmental changes in southern Kamchatka, Far Eastern Russia, inferred from a pollen and testate amoebae peat succession record. Global and Planetary Change, 134, 142-154
Open this publication in new window or tab >>Holocene environmental changes in southern Kamchatka, Far Eastern Russia, inferred from a pollen and testate amoebae peat succession record
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2015 (English)In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 134, p. 142-154Article in journal (Refereed) Published
Abstract [en]

High resolution palaeoenvironmental records in Far-Eastern Russia are rare, and the Kamchatka Peninsula is among the least studied areas of the region. This paper describes a record spanning the last ca. 11,000 yr, obtained from a bog in the southern part of Kamchatka. The radiocarbon dated core was analysed for pollen, testate amoebae, charcoal and loss-on-ignition (LOI). The vegetation during the early Holocene was dominated by grasses (Poaceae), birch (Betula) and heath (Ericaceae p. p.). Around 10,300 cal yr BP there was a substantial change in the vegetation cover to shrub alder (Alnus viridis s.I.) stands with sedges and ferns (Polypodiophyta) as well as herbs such as meadow rue (Thalictrum) in the understory. In the surroundings of Utka peatlands started to form. The variations in the vegetation cover were most probably caused by climatic changes. At the beginning of sediment accumulation, before 10,300 cal yr BP, the composition of the vegetation points to cooler summers and/or decreased annual precipitation. Around 10,300 cal yr BP, changes in vegetation occurred due to rising temperatures and/or changed water regimes. Increased abundancies of dry indicating testate amoebae after 9100 cal yr BP point to intermediate to dry soil conditions. Between 8600 and 7700 cal yr BP tree alder (Alnus incana) was widely spread at the site which probably indicates optimal environmental conditions. The tephra layer at 381-384.5 cm (ca. 8500 cal yr BP) produces a strong impact on the testate amoebae assemblages. At 7700 cal yr BP there was a sudden drop of A. incana in the local vegetation. From this time on, A. incana and also A. viridis decrease continuously whereas Betula gradually increases. The upper part of the sequence (after 6300 cal yr BP) shows higher abundancies of meadowsweet (Filipendula) and sweet gale (Myrica) pollen. After 6300 cal yr BP, changes in testate amoebae demonstrate variable soil moisture conditions at the site. Between 3700 and 1800 cal yr BP, wet conditions dominate as dry indicating testate amoebae decrease. After 1800 cal yr BP soil conditions become more variable again but this time with dry dominating testate amoebae. In contrast to surrounding regions, there is no evidence of trees such as spruce or larch growing in the surroundings of the site even though those trees are characteristic of many eastern Siberian sites. This difference might be because of the maritime influence of the Okhotsk Sea. Even dwarf pine (Pinus pumila), which is currently widely dispersed in northern Kamchatka, became part of the local vegetation only during the last 700 yr.

Keyword
Holocene, Kamchatka, Pollen, Testate amoebae, Landscape development, Climate change
National Category
Geosciences, Multidisciplinary
Identifiers
urn:nbn:se:uu:diva-270628 (URN)10.1016/j.gloplacha.2015.09.010 (DOI)000365369900013 ()
Funder
Swedish Research Council, 621-2004-5224Swedish Research Council, 621-2005-4444
Available from: 2016-01-01 Created: 2016-01-01 Last updated: 2017-12-01Bibliographically approved
Willis, K. J., Bennett, K. D., Burrough, S. L., Macias-Fauria, M. & Tovar, C. (2013). Determining the response of African biota to climate change: using the past to model the future. Philosophical Transactions of the Royal Society of London. Biological Sciences, 368(1625), 20120491
Open this publication in new window or tab >>Determining the response of African biota to climate change: using the past to model the future
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2013 (English)In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 368, no 1625, p. 20120491-Article, review/survey (Refereed) Published
Abstract [en]

Prediction of biotic responses to future climate change in tropical Africa tends to be based on two modelling approaches: bioclimatic species envelope models and dynamic vegetation models. Another complementary but underused approach is to examine biotic responses to similar climatic changes in the past as evidenced in fossil and historical records. This paper reviews these records and highlights the information that they provide in terms of understanding the local-and regional-scale responses of African vegetation to future climate change. A key point that emerges is that a move to warmer and wetter conditions in the past resulted in a large increase in biomass and a range distribution of woody plants up to 400-500 km north of its present location, the so-called greening of the Sahara. By contrast, a transition to warmer and drier conditions resulted in a reduction in woody vegetation in many regions and an increase in grass/savanna-dominated landscapes. The rapid rate of climate warming coming into the current interglacial resulted in a dramatic increase in community turnover, but there is little evidence for widespread extinctions. However, huge variation in biotic response in both space and time is apparent with, in some cases, totally different responses to the same climatic driver. This highlights the importance of local features such as soils, topography and also internal biotic factors in determining responses and resilience of the African biota to climate change, information that is difficult to obtain from modelling but is abundant in palaeoecological records.

Keyword
Africa, ecosystem services, climate change, aridity, precipitation, palaeoecology
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-220962 (URN)10.1098/rstb.2012.0491 (DOI)000331220500018 ()
Available from: 2014-03-24 Created: 2014-03-24 Last updated: 2017-12-05Bibliographically approved
Parducci, L., Matetovici, I., Fontana, S. L., Bennett, K. D., Suyama, Y., Haile, J., . . . Willerslev, E. (2013). Molecular- and pollen-based vegetation analysis in lake sediments from central Scandinavia. Molecular Ecology, 22(13), 3511-3524
Open this publication in new window or tab >>Molecular- and pollen-based vegetation analysis in lake sediments from central Scandinavia
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2013 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 22, no 13, p. 3511-3524Article in journal (Refereed) Published
Abstract [en]

Plant and animal biodiversity can be studied by obtaining DNA directly from the environment. This new approach in combination with the use of generic barcoding primers (metabarcoding) has been suggested as complementary or alternative to traditional biodiversity monitoring in ancient soil sediments. However, the extent to which metabarcoding truly reflects plant composition remains unclear, as does its power to identify species with no pollen or macrofossil evidence. Here, we compared pollen-based and metabarcoding approaches to explore the Holocene plant composition around two lakes in central Scandinavia. At one site, we also compared barcoding results with those obtained in earlier studies with species-specific primers. The pollen analyses revealed a larger number of taxa (46), of which the majority (78%) was not identified by metabarcoding. The metabarcoding identified 14 taxa (MTUs), but allowed identification to a lower taxonomical level. The combined analyses identified 52 taxa. The barcoding primers may favour amplification of certain taxa, as they did not detect taxa previously identified with species-specific primers. Taphonomy and selectiveness of the primers are likely the major factors influencing these results. We conclude that metabarcoding from lake sediments provides a complementary, but not an alternative, tool to pollen analysis for investigating past flora. In the absence of other fossil evidence, metabarcoding gives a local and important signal from the vegetation, but the resulting assemblages show limited capacity to detect all taxa, regardless of their abundance around the lake. We suggest that metabarcoding is followed by pollen analysis and the use of species-specific primers to provide the most comprehensive signal from the environment.

Keyword
ancient DNA, barcoding, environmental DNA, palaeoecology, pollen
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-204270 (URN)10.1111/mec.12298 (DOI)000320942000010 ()
Available from: 2013-07-30 Created: 2013-07-29 Last updated: 2017-12-06Bibliographically approved
de Boer, E. J., Hooghiemstra, H., Florens, F. B., Baider, C., Engels, S., Dakos, V., . . . Bennett, K. D. (2013). Rapid succession of plant associations on the small ocean island of Mauritius at the onset of the Holocene. Quaternary Science Reviews, 68, 114-125
Open this publication in new window or tab >>Rapid succession of plant associations on the small ocean island of Mauritius at the onset of the Holocene
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2013 (English)In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 68, p. 114-125Article in journal (Refereed) Published
Abstract [en]

The island of Mauritius offers the opportunity to study the poorly understood vegetation response to climate change on a small tropical oceanic island. A high-resolution pollen record from a 10 m long peat core from Kanaka Crater (560 m elevation, Mauritius, Indian Ocean) shows that vegetation shifted from a stable open wet forest Last Glacial state to a stable closed-stratified-tall-forest Holocene state. An ecological threshold was crossed at similar to 11.5 cal ka BP, propelling the forest ecosystem into an unstable period lasting similar to 4000 years. The shift between the two steady states involves a cascade of four abrupt (<150 years) forest transitions in which different tree species dominated the vegetation for a quasi-stable period of respectively similar to 1900, similar to 1100 and similar to 900 years. We interpret the first forest transition as climate-driven, reflecting the response of a small low topography oceanic island where significant spatial biome migration is impossible. The three subsequent forest transitions are not evidently linked to climate events, and are suggested to be driven by internal forest dynamics. The cascade of four consecutive events of species turnover occurred at a remarkably fast rate compared to changes during the preceding and following periods, and might therefore be considered as a composite tipping point in the ecosystem. We hypothesize that wet gallery forest, spatially and temporally stabilized by the drainage system, served as a long lasting reservoir of biodiversity and facilitated a rapid exchange of species with the montane forests to allow for a rapid cascade of plant associations.

Keyword
Indian Ocean, Island ecology, Late Quaternary, Pollen record, Climate change, Species turnover, Regime shift
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-200652 (URN)10.1016/j.quascirev.2013.02.005 (DOI)000318383900007 ()
Available from: 2013-06-03 Created: 2013-06-03 Last updated: 2017-12-06Bibliographically approved
Parducci, L., Jorgensen, T., Tollefsrud, M. M., Elverland, E., Alm, T., Fontana, S. L., . . . Willerslev, E. (2012). Glacial Survival of Boreal Trees in Northern Scandinavia. Science, 335(6072), 1083-1086
Open this publication in new window or tab >>Glacial Survival of Boreal Trees in Northern Scandinavia
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2012 (English)In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 335, no 6072, p. 1083-1086Article in journal (Refereed) Published
Abstract [en]

It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west-an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trondelag in central Norway dating back similar to 10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andoya refugium in northwestern Norway as early as similar to 22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-171400 (URN)10.1126/science.1216043 (DOI)000300931100042 ()
Available from: 2012-03-20 Created: 2012-03-19 Last updated: 2017-12-07Bibliographically approved
Bennett, K. D., Bhagwat, S. A. & Willis, K. J. (2012). Neotropical refugia. The Holocene, 22(11), 1207-1214
Open this publication in new window or tab >>Neotropical refugia
2012 (English)In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 22, no 11, p. 1207-1214Article in journal (Refereed) Published
Abstract [en]

Patterns of endemism in the Neotropics have been explained by restriction of forest to 'refugia' in arid cold-stages of the Quaternary (Haffer J (1969) Speciation in Amazonian forest birds. Science 165: 131-137). The palaeoecological record, however, shows no such forest contraction. We review palaeoecological and phylogenetic data on the response of Neotropical taxa and communities to climatic changes of the Cenozoic. Solar insolation varies over this period with latitude and geography, including shifts in opposite directions between high and low latitudes. In the Neotropics, distribution and abundance patterns originate on a wide range of timescales through the Cenozoic, down to the currently dominant precession forcing (20 kyr). In contrast, distributions and abundances at higher latitudes are controlled by obliquity forcing (40 kyr). The patterns observed by Haffer (1969) are likely derived from pre-Quaternary radiations and are not inconsistent with palaeoecological findings of continuous forest cover in major areas of the Neotropics during the Quaternary. The relative proportions of speciation processes have changed through time between predominantly sympatric to predominantly allopatric depending on the prevailing characteristics of orbitally forced climatic changes. Behaviour of Neotropical organisms and ecosystems on long timescales may be influenced much more by precessional forcing than by the obliquity forcing that controls high-latitude climate change and glaciations.

Keyword
Cenozoic, climate change, evolution, Neotropics, palaeoecology, Quaternary
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-186018 (URN)10.1177/0959683612450204 (DOI)000309938500002 ()
Available from: 2012-11-28 Created: 2012-11-27 Last updated: 2017-12-07Bibliographically approved
Fontana, S. L., Martha Bianchi, M. & Bennett, K. D. (2012). Palaeoenvironmental changes since the Last Glacial Maximum: Patterns, timing and dynamics throughout South America. The Holocene, 22(11), 1203-1206
Open this publication in new window or tab >>Palaeoenvironmental changes since the Last Glacial Maximum: Patterns, timing and dynamics throughout South America
2012 (English)In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 22, no 11, p. 1203-1206Article in journal, Editorial material (Other academic) Published
Abstract [en]

The vast diversity of present vegetation and environments that occur throughout South America (12 degrees N to 56 degrees S) is the result of diverse processes that have been operating and interacting at different spatial and temporal scales. Global factors, such as the concentration of CO2 in the atmosphere, may have been significant for high altitude vegetation during times of lower abundance, while lower sea levels of glacial stages potentially opened areas of continental shelf for colonisation during a substantial portion of the Quaternary. Latitudinal variation in orbital forcing has operated on a regional scale. The pace of climate change in the tropics is dominated by precessional oscillations of c. 20 kyr, while the high latitudes of the south are dominated by obliquity oscillations of c. 40 kyr. In particular, seasonal insolation changes forced by precessional oscillations must have had important consequences for the distribution limits of species, with potentially different effects depending on the latitude. The availability of taxa, altitude and human impact, among other events, have locally influenced the environments. Disentangling the different forcing factors of environmental change that operate on different timescales, and understanding the underlying mechanisms leads to considerable challenges for palaeoecologists. The papers in this Special Issue present a selection of palaeoecological studies throughout South America on vegetation changes and other aspects of the environment, providing a window on the possible complexity of the nature of transitions and timings that are potentially available.

Keyword
climate change, Holocene, palaeoecology, Quaternary, South America, vegetation
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-187230 (URN)10.1177/0959683612451184 (DOI)000309938500001 ()
Available from: 2012-12-06 Created: 2012-12-04 Last updated: 2017-12-07Bibliographically approved
Fontana, S. L. & Bennett, K. D. (2012). Postglacial vegetation dynamics of western Tierra del Fuego. The Holocene, 22(11), 1337-1350
Open this publication in new window or tab >>Postglacial vegetation dynamics of western Tierra del Fuego
2012 (English)In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 22, no 11, p. 1337-1350Article in journal (Refereed) Published
Abstract [en]

The southern fringes of the South American landmass provide a rare opportunity to examine the development of moorland vegetation with sparse tree cover in a wet, cool temperate climate of the Southern Hemisphere. We present a record of changes in vegetation over the past 17,000 years, from a lake in extreme southern Chile (Isla Santa Inés, Magallanes region, 53°38.97S; 72°25.24W), where human influence on vegetation is negligible. The western archipelago of Tierra del Fuego remained treeless for most of the Lateglacial period; Lycopodium magellanicum, Gunnera magellanica and heath species dominated the vegetation. Nothofagus may have survived the last glacial maximum at the eastern edge of the Magellan glaciers from where it spread southwestwards and established in the region at around 10,500 cal. yr BP. Nothofagus antarctica was likely the earlier colonizing tree in the western islands, followed shortly after by Nothofagus betuloides. At 9000 cal. yr BP moorland communities expanded at the expense of Nothofagus woodland. Simultaneously, Nothofagus species shifted to dominance of the evergreen Nothofagus betuloides and the Magellanic rain forest established in the region. Rapid and drastic vegetation changes occurred at 5200 cal. yr BP, after the Mt Burney MB2 eruption, including the expansion and establishment of Pilgerodendron uviferum and the development of mixed Nothofagus-Pilgerodendron-Drimys woodland. Scattered populations of Nothofagus, as they occur today in westernmost Tierra del Fuego may be a good analogue for Nothofagus populations during the Lateglacial in eastern sites.

Keyword
Holocene, Lateglacial, Magellanic moorland, Nothofagus, pollen analysis, postglacial vegetation dynamics, Tierra del Fuego
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-186011 (URN)10.1177/0959683612444144 (DOI)000309938500013 ()
Available from: 2012-11-28 Created: 2012-11-27 Last updated: 2017-12-07Bibliographically approved
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