Late Quaternary vegetation dynamics and hydroseral development in a shrub swamp in southern Ontario, Canada

1999 ◽  
Vol 36 (10) ◽  
pp. 1603-1616 ◽  
Author(s):  
M Jane Bunting ◽  
Barry G Warner
Keyword(s):  
Deciduous Forest ◽  
Late Quaternary ◽  
Sediment Accumulation ◽  
Central Area ◽  
Open Water ◽  
Sedimentation Rates ◽  
Marsh Vegetation ◽  
Southern Ontario ◽  
Aquatic Mosses ◽  
Tall Shrub

Using a multiple-core paleoecological approach, we studied the development of a small kettle-hole wetland (informal name Spiraea wetland) in southern Ontario. The sedimentary record begins at around 11 700 BP, when Picea and herbs characteristic of a disturbed environment were the principal components of the upland vegetation. These were replaced by ca. 9500 BP by Pinus dominance, which persisted until at least 6300 BP. Mixed deciduous forest communities then developed and were only disturbed by Euro-Canadian settlement in the last few hundred years. Initially, the basin contained an open lake, which was progressively colonized by a range of aquatic plants, becoming a shallow open water wetland community by 9500 BP. A marsh community spread rapidly from the edge of the basin, and a mat of aquatic mosses filled the central area of open water before marsh vegetation became established there. Between 6300 and 1500 BP, there is a marked decrease in sedimentation rates, and the paleoecological data imply that the vegetation communities at the coring points varied between marsh, shrub swamp, and conditions where no net sediment accumulation occurred. Sedimentation rates increased in the upper part of the core, as the modern tall-shrub swamp developed.

Late Quaternary vegetation dynamics and hydroseral development in a Thuja occidentalis swamp in southern Ontario

1996 ◽  
Vol 33 (10) ◽  
pp. 1439-1456 ◽  
Author(s):  
M. Jane Bunting ◽  
Barry G. Warner ◽  
Ramon Aravena
Keyword(s):  
Vegetation Dynamics ◽  
Accumulation Rate ◽  
Late Quaternary ◽  
Sediment Accumulation ◽  
Open Water ◽  
Internal Factors ◽  
Southern Ontario ◽  
Thuja Occidentalis ◽  
Open Water Body ◽  
Water Community

Palaeoecological data from a small swamp in southern Ontario are used to reconstruct postglacial upland and wetland vegetation dynamics and assess the relative importance of autogenic and allogenic factors in wetland development. The inferred upland forest dynamics are comparable in timing and trend with lake records from the region. During the early Holocene, the shallow open water body became increasingly colonized by aquatic plants, until at around 8000 BP when the shallow open water community was replaced by a Larix swamp. At around 5600 BP, there was an apparent reversal in the wetland progression and Typha was locally dominant. There is a possible hiatus in the sedimentary record at around this time. Thereafter, a Thuj–Abies–Picea swamp community developed. The data suggest that internal factors and local events such as beaver activity could be equally or more important than regionally acting factors such as climatic change in controlling the hydroseral progression. The changing nature of the wetland community led to a 40-fold variation in sediment accumulation rate during the Holocene, emphasizing the importance of establishing a good chronology and using a multiple-core approach in such systems.

scholarly journals Modeling photovoltaic solar farm site suitability using a multi-criteria evaluation in Southern, Ontario, Canada

2021 ◽  
Author(s):  
Scott Mackey
Keyword(s):  
Transmission Lines ◽  
Power Plants ◽  
Central Area ◽  
Solar Panels ◽  
Southern Ontario ◽  
West Central ◽  
Multi Criteria Evaluation ◽  
Solar Energy Industry ◽  
Populated Region ◽  
Hierarchy Process

Canada’s solar energy industry has seen significant growth in recent years. More specifically, southern Ontario, Canada’s most densely populated region, hosts over 100 industrial-scale solar farms. These large arrays of interconnected solar panels convert incoming global horizontal irradiance into electricity. This study is a location-based analysis investigating the suitability of southern Ontario’s lands for hosting solar farms. The objectives are: (1) determine the most applicable variables and methods that are replicable in the southern Ontario region; (2) identify and analyze the amount and location of suitable areas; and (3) understand and explain any discrepancies between the locations of existing solar farm power plants and optimal locations. This research produces a land suitability model of southern Ontario’s solar farm capacity. It utilizes an analytical hierarchy process, a type of multi-criteria evaluation, in order to identify criteria, classify and weigh variables, and overlay inputs. The data employed are incoming solar radiation, cloud cover, land use, hydro transmission lines, major road networks, slope, and cultural areas. The results suggest much of the northern portions of southern Ontario are not well adapted for hosting solar farms, while large parts of southwest and west-central are very suitable or mostly suitable. In particular, a west-central area remains untapped for solar farming, despite being highly suitable. These results are then compared to the approximate locations of existing solar farms, and discrepancies are discussed.

Distribution of biogenic silica in the surficial sediments of Lake Michigan

1986 ◽  
Vol 23 (9) ◽  
pp. 1442-1449 ◽  
Author(s):  
Daniel J. Conley ◽  
Claire L. Schelske ◽  
Brian G. Dempsey ◽  
Charles D. Campbell ◽  
Teresa L. Newberry
Keyword(s):  
Spatial Distribution ◽  
Biogenic Silica ◽  
Lake Michigan ◽  
Sediment Accumulation ◽  
Sedimentation Rates ◽  
Surficial Sediments ◽  
Sediment Samples ◽  
High Productivity ◽  
Lake Bottom ◽  
High Concentrations

The spatial distribution of biogenic silica (BSi) in the surficial sediments of Lake Michigan is described from Shipek grab samples collected in 1975 and gravity cores obtained in 1983. Significantly smaller surficial BSi concentrations in the 1975 samples were attributed primarily to the inability of a Shipek grab to collect intact surficial sediment samples. Lower concentrations o.f BSi were found in nondepositional and transitional areas of sediment accumulation than in depositional basins. Therefore, BSi accumulation is restricted primarily to the 40% of the lake bottom where sediments are presently accumulating. High concentrations found in Green Bay surficial sediments are related to high productivity in the bay coupled with inputs of new silica from the Fox River. In the open lake, BSi concentrations of surficial sediments in depositional basins appeared to vary inversely with sedimentation rate in that lower BSi concentrations were found in areas with higher sedimentation rates.

scholarly journals Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints

2011 ◽  
Vol 62 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Dario Gioia ◽  
Claudio Martino ◽  
Marcello Schiattarella
Keyword(s):  
Sediment Accumulation ◽  
Radiometric Dating ◽  
Sedimentation Rates ◽  
Southern Apennines ◽  
Short Term ◽  
Small Catchment ◽  
Fluvial Terraces ◽  
Denudation Rates ◽  
Land Surfaces

Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints Age constraints of geomorphological markers and consequent estimates of long- to short-term denudation rates from southern Italy are given here. Geomorphic analysis of the valley of the Tanagro River combined with apatite fission track data and radiometric dating provided useful information on the ages and evolution of some significant morphotectonic markers such as regional planated landscapes, erosional land surfaces and fluvial terraces. Reconstruction of paleotopography and estimation of the eroded volumes were perfomed starting from the plano-altimetric distribution of several orders of erosional land surfaces surveyed in the study area. Additional data about denudation rates related to the recent and/or active geomorphological system have been obtained by estimating the amount of suspended sediment yield at the outlet of some catchments using empirical relationships based on the hierarchical arrangement of the drainage network. Denudation rates obtained through these methods have been compared with the sedimentation rates calculated for two adjacent basins (the Pantano di San Gregorio and the Vallo di Diano), on the basis of published tephrochronological constraints. These rates have also been compared with those calculated for the historical sediment accumulation in a small catchment located to the north of the study area, with long-term exhumation data from thermochronometry, and with uplift rates from the study area. Long- and short-term denudation rates are included between 0.1 and 0.2 mm/yr, in good agreement with regional data and long-term sedimentation rates from the Vallo di Diano and the Pantano di San Gregorio Magno basins. On the other hand, higher values of exhumation rates from thermochronometry suggest the existence of past erosional processes faster than the recent and present-day exogenic dismantling. Finally, the comparison between uplift and denudation rates indicates that the fluvial erosion did not match the tectonic uplift during the Quaternary in this sector of the chain. The axial zone of the southern Apennines should therefore be regarded as a landscape in conditions of geomorphological disequilibrium.

Labrador Sea bio-, tephro-, oxygen isotopic stratigraphy and Late Quaternary paleoceanographic trends

1980 ◽  
Vol 17 (7) ◽  
pp. 831-854 ◽  
Author(s):  
R. H. Fillon ◽  
J. C. Duplessy
Keyword(s):  
Deep Water ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Open Water ◽  
Labrador Sea ◽  
Surface Cooling ◽  
Stratigraphic Framework ◽  
Stage 4 ◽  
Oxygen Isotopic ◽  
Stage 1

A stratigraphic framework for eastern Labrador Sea cores has been developed for the interval 0–90 000 years BP through analysis of oxygen isotopes, volcanic ash, benthonic foraminifera, and the radiolarian Diplocyclas davisiana. Benthonic and planktonic foraminiferal isotope stratigraphy and the time scale of Shackleton and Opdyke provide a basis for the approximate dating of a series of marker events which include ash zones at ca. 59 000 and ≤ 21 000 years BP; benthonic foraminiferal abundance maxima at ca. 83 000, 75 000, 60 000, 19 000, and 3000 years BP; and D. davisiana percentage maxima at ca. 90 000, 73 000, 64 000, 54 000, 45 000 – 32 000, and 10 000 years BP. Incursions of subpolar planktonic foraminifera into the area during parts of isotopic stage 2 (between about 13 000 and 25 000 years BP but probably excluding the 15 000–18 000 years BP glacial maximum interval) and during the isotopic stage 4/5a transition (around 75 000 years BP) suggest that the eastern Labrador Sea was free of sea ice, at least in summer during periods of rapid continental ice sheet growth which lead to the isotopic stage 4 and stage 2 glacial maxima. A larger than normal stage 1/stage 2 difference in the isotopic composition of benthonic foraminifera (1.8‰) implies that this open water and attendant surface cooling was a potential source for colder than modern deep water. In contrast the Norwegian Sea was a reservoir of warmer than modern deep water during the last glacial.

Neanderthal landscapes and subsistence strategies during late Quaternary glacial-interglacial periods: insights from the avian assemblages of Grotta del Cavallo (Apulia, Southern Italy)

2021 ◽  
Author(s):  
Lisa Carrera ◽  
Daniele Scarponi ◽  
Fabio Martini ◽  
Lucia Sarti ◽  
Marco Pavia
Keyword(s):  
Southern Italy ◽  
Late Quaternary ◽  
Sediment Accumulation ◽  
Sampling Effort ◽  
Paleolithic Site ◽  
Climate Conditions ◽  
Bird Assemblages ◽  
Depositional Processes ◽  
Feeding Activities ◽  
The Rich

<p>Grotta del Cavallo, a well-known Paleolithic site in Southern Italy (Nardò, Apulia), preserves one of the most important Italian Middle Paleolithic sequences. Its stratigraphic succession records the presence of Neanderthals from Marine Isotope Stage (MIS) 7 to 3, providing substantial insights on their lifeways. Here we present the taxonomic and taphonomic analysis of the bird assemblages associated to Neanderthal occupation. The rich avifaunal assemblages allowed paleoenvironmental and paleoclimatic reconstructions, noticeably improving the reconstruction of the landscape that was exploited by Neanderthals throughout the last glacial-interglacial cycles. Based on the bird taxa identified in the assemblages, Grotta del Cavallo was mainly surrounded by extensive grasslands and shrublands, with scattered open woodland and rocky outcrops, during MIS 7, 6 and 3. The coastal plain, that is currently underwater due to Holocene relative sea-level rise, hosted wetlands in the cooler periods, when it was exposed. In the cool-temperate climatic phase attributed to MIS 3, bird taxa of water and wet environments proportionally increased, as well as coverage-based rarefied richness values. This is possibly due to the expansion of wetland areas, linked to more humid conditions, or to the shorter distance of the wetland settings from the cave, compared to MIS 6 (glacial period). A consequent higher heterogeneity of the landscape is retained to drive the increased richness. The sampling effort allowed to retrieve bird taxa that provided significant paleoclimatic insights, such as Branta leucopsis, an arctic breeder, and other species currently spread at higher altitudes, that reinforce previously obtained geochemical derived inference of climate conditions cooler than the present ones. The bird assemblages also provided the first occurrence ever of Larus genei, the first Italian occurrence of Emberiza calandra, the oldest Italian occurrence of Podiceps nigricollis, and the occurrence of Sylvia communis (a species rarely retrieved in the fossil record). Ordination analyses of the bird dataset detected the drivers of taphonomic degradation and the agents responsible for the accumulation of the avian bones: modifications are mainly due to physical sin- and post-depositional processes, whereas accumulation is mainly attributed to short-range physical processes of sediment accumulation, feeding activities of nocturnal raptors and, to a lesser extent, human activities. In detail, traces found on a few bones suggest that Neanderthals introduced some of the birds in the cave with alimentary purposes, providing the earliest Italian evidence of bird exploitation ever.</p>

Sign in / Sign up

Export Citation Format

Share Document