207 research outputs found
Investigating the early pottery Neolithic of northern Syria:New evidence from Tell Sabi Abyad
Investigating the early pottery Neolithic of northern Syria:New evidence from Tell Sabi Abyad
Palynologisch onderzoek aan een pingo-ruïne bij Oosterwold (OTJO2 - gemeente Ooststellingwerf; provincie Fryslân)
Cereal cultivation at Swifterbant?:Neolithic Wetland Farming on the North European Plain
The transition to early agriculture on the North European Plain is a much debated issue in which emphasis is placed on the available pollen evidence. It has been suggested that cereal cultivation was probably practiced in the upland areas and surplus yields were brought to the wetland sites. An alternative model that gives special attention to crop assemblages, flooding, and yields and is illustrated with evidence from the type-location sites of Swifterbant, dated between 4300 and 4000 BC, envisions cereal cultivation in the wetlands themselves. Evidence for early agriculture is found in particular in pollen diagrams, diatom analysis, and large numbers of cereal remains. It appears that small-scale cereal cultivation may have been possible and attractive in addition to hunting and gathering in wetland sites because of their variety of biotopes, including areas suitable for agriculture
Palynologisch onderzoek aan een pingo-ruïne bij Oosterwold (OTJO2 - gemeente Ooststellingwerf; provincie Fryslân)
Palynologisch onderzoek aan een pingo-ruïne bij Oosterwold (OTJO2 - gemeente Ooststellingwerf; provincie Fryslân)
Hydrochorous Seed Dispersal in Riparian Forests Altered by Urbanization
While riparian habitat alterations from urban stream syndrome are known to affect vegetation establishment and survival, the degree to which riparian seed delivery by hydrochory is affected by urbanization is unclear. We hypothesized that (1) there would be a reduction in the overall number of seeds deposited by streams as watershed urbanization increased; and (2) in the most urbanized watersheds, seeds deposited by water would be predominantly from species with traits favoring dispersal in general, including tall stature and high seed production, and favoring deposition by water in particular, including large seed size and the presence of a dispersal appendage. Nine riparian forests, selected using a stratified random approach, were studied along a gradient of watershed impervious surface area (1–41%) in the Portland, Oregon, USA , metropolitan region. Seeds deposited by water were collected using turf traps four times over a 15‐month period that spanned both wet and dry seasonal conditions. Along the urbanization gradient of increasing total impervious area, there was a significant decrease in the total number of seeds deposited by hydrochory (adjusted R 2 = 0.74; P \u3c 0.01). Deposition of seeds from shade‐tolerant and native taxa by water decreased as surrounding urbanization increased (adjusted R 2 = 0.57; P \u3c 0.05). Deposition of non‐native seeds increased as urban development within 500 m from the riparian area increased (adjusted R 2 = 0.79, P \u3c 0.01). The findings demonstrate that seed dispersal patterns in riparian areas are altered by urbanization. During higher rainfall seasons, flashy hydrology and stream bank scour appear to alter seed delivery in highly urban watersheds. While the urban stream syndrome contributes to altered dispersal, other urbanization pressures that affect source populations, such as vegetation removal, also limit seed delivery to riparian sites. Overall, our results suggest that urbanization can limit the regeneration processes that maintain vegetation communities in riparian forests
Palynologisch onderzoek aan de pingo-ruïne TYPA2 (Burgum; gemeente Tytsjerksteradiel; provincie Frieslân)
Palynologisch onderzoek aan de pingo-ruïne FRCP2-10 (Hurdegaryp; gemeente Tytsjerksteradiel; provincie Frieslân)
Palynologisch onderzoek aan een pingo-ruïne bij Oosterwold (OTJO2 - gemeente Ooststellingwerf; provincie Fryslân)
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