Middle Holocene humidity increase in Florida: climate or sea-level?

Donders, Timme H.

doi:10.1016/j.quascirev.2014.09.011

Cited by 11 publications

(10 citation statements)

References 29 publications

(51 reference statements)

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“…As Florida gradually became wetter during the middle Holocene (between 7,000 and 5,500 cal yrs BP, zone 2 in our record) the sclerophyllous oak and open prairie plant communities were replaced by modern vegetation communities, largely dominated by pine forests, at least in upland sites [ 3 , 47 ]. The first significant change in δ 13 C TOC values occurred at ~6,500 cal yrs BP (350 cm core depth) and corresponds to this environmental change.…”

Section: Discussionmentioning

confidence: 99%

“…From 250 cm core depth (~5,000 cal yrs BP) to the present (AD 2013) (zone 1), the organic matter becomes progressively depleted in 13 C. This depletion coincides with a second stage of increased precipitation in Florida that occurred between 5,000 and 3,000 cal yrs BP [ 47 ]. Pollen-based reconstructions of summer precipitation show persistently wetter conditions after 3,000 cal yrs BP, which were related to the intensification of ENSO [ 46 ].…”

Section: Discussionmentioning

confidence: 99%

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Sediment biomarkers elucidate the Holocene ontogeny of a shallow lake

et al. 2018

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We carried out geochemical analyses on a sediment core from Lake Harris, Florida (USA) to identify sources of organic matter to the sediment throughout the Holocene, and relate changes in those sources to shifts in past climate and environmental conditions. We hypothesized that the sources of organic matter changed in response to regional hydrologic shifts following de-glaciation, and to human population expansion in the state during the 20th century. Hydroclimate shifts in Florida were related to: 1) a steady rise in relative sea level and the fresh water table that began in the early Holocene, 2) wetland formation and expansion ca. 5,000 cal yrs BP, and 3) the onset of the modern El Niño (ENSO) cycle ~3,000 cal yrs BP. Stratigraphic changes in sediment variables from Lake Harris reflect each of these hydroclimate periods. Early in the Holocene, Lake Harris was a marsh-like system in a relatively dry, open-prairie environment. Organic sediments deposited at that time were derived largely from terrestrial sources, as inferred from high TOC/TN ratios, a dominance of longer-chain of n-alkanes (n-C29-31), relatively negative organic carbon isotope values (δ13CTOC), and low biogenic silica concentrations. In the middle Holocene, a positive shift in δ13CTOC coincided with the onset of wetter conditions in Florida. Submerged macrophyte biomarkers (n-C21-23) dominated, and during that period bulk organic carbon isotope values were most similar to δ13C values of mid-chain-length n-alkanes. In the late Holocene, δ13CTOC values declined, CaCO3 levels decreased to trace amounts, organic carbon concentrations increased and diatom biogenic silica concentrations increased from 10 to 120 mg g-1. Around 2,900 cal yrs BP, the effects of ENSO intensified and many Florida lakes deepened to their current limnetic state. Concentrations of algal and cyanobacterial biomarkers in the Lake Harris core increased by orders of magnitude after about AD 1940, in response to human-induced eutrophication, an inference supported by values of δ15N that fluctuate around zero.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Sediment biomarkers elucidate the Holocene ontogeny of a shallow lake

et al. 2018

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“…For example, periods of increased El Niño-like conditions are responsible for increased precipitation in the region, which in turn has impacted vegetation communities (Donders et al, 2005;Donders, 2011). On longer times scales, driven by the mean southward position of the Intertropical Convergence Zone (ITCZ), sustained aridity events also shaped the timing of tree island initiation and expansion (Willard et al, 2006;Bernhardt, 2011).…”

Section: Understanding Landscape Scale Responses To Climate and Anthrmentioning

confidence: 99%

The Role of Paleoecology in Restoration and Resource Management—The Past As a Guide to Future Decision-Making: Review and Example from the Greater Everglades Ecosystem, U.S.A

2017

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Resource managers around the world are challenged to develop feasible plans for sustainable conservation and/or restoration of the lands, waters, and wildlife they administer-a challenge made greater by anticipated climate change and associated effects over the next century. Increasingly, paleoecologic and geologic archives are being used to extend the period of record of observed data and provide information on centennial to millennial scale responses to long-term drivers of ecosystem change. The development of paleoecology from an emerging field investigating past environments to a highly relevant applied science is reviewed and general examples of the application of paleoecologic research to resource management questions in diverse habitats and regions are provided. Specific examples of the application of paleoecologic research to the restoration of the Greater Everglades Ecosystem of south Florida (U.S.A) are presented. Conducting valuable scientific research that would benefit resource management decisions, however, is not enough. Scientists and resource managers need to be engaged in collaborative discussions from the beginning of the research process to ensure that management questions are being addressed and that the science reaches the people who will benefit from the information. Paleoecology and related disciplines provide an understanding of how ecosystems and individual species function and change over time in response to both natural and anthropogenic drivers. Information on pre-anthropogenic baseline conditions is provided by paleoecologic research, but it is the detection of long-term trends and cycles that allow resource managers to set realistic goals and targets by moving away from the fixed-point baseline concept to one of dynamic landscapes that anticipates and incorporates an expectation of change into decision-making.

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“…Major long-term hydrological changes have been reported in Quaternary pollen records from central Florida lake deposits, where the alteration between oak-ragweed and pinedominated vegetation prominently reflects drier and wetter periods over the last glacial-interglacial cycle (Watts, 1969(Watts, , 1971(Watts, , 1975(Watts, , 1980Grimm et al, 1993Grimm et al, , 2006Watts and Hansen, 1994;Willard et al, 2007), and which are likely forced by changes in AMOC intensity (Donders et al, 2011). During the Holocene, regional vegetation again shifted from dry oak to wetter pine vegetation cover across the peninsula starting around 6.5 ± 1 cal ka BP (Watts and Hansen, 1994;Grimm et al, 2006), whereby the humidity increase was more prominent farther south, suggesting forcing though intensification of the El Niño Southern Oscillation (Donders, 2014). Florida estuarine deposits show that this vegetation change co-occurs with an increase in runoff, pointing to increased precipitation in combination with sea-level rise as important driver (Van Soelen et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of wetland hydrology to external climate forcing in central Florida

et al. 2015

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Available proxy records from the Florida peninsula give a varying view on hydrological changes during the late Holocene. Here we evaluate the consistency and sensitivity of local wetland records in relation to hydrological changes over the past ~ 5 ka based on pollen and diatom proxies from peat cores in Highlands Hammock State Park, central Florida. Around 5 cal ka BP, a dynamic floodplain environment is present. Subsequently, a wetland forest establishes, followed by a change to persistent wet conditions between ~ 2.5 and 2.0 ka. Long hydroperiods remain despite gradual succession and basin infilling with maximum wet conditions between ~ 1.3 and 1.0 ka. The wet phase and subsequent strong drying over the last millennium, as indicated by shifts in both pollen and diatom assemblages, can be linked to the early Medieval Warm Period and Little Ice Age, respectively, driven by regionally higher sea-surface temperatures and a temporary northward migration of the Intertropical Convergence Zone. Changes during the 20th century are the result of constructions intended to protect the Highlands Hammock State Park from wildfires. The multiple cores and proxies allow distinguishing local and regional hydrological changes. The peat records reflect relatively subtle climatic changes that are not evident from regional pollen records from lakes.

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Middle Holocene humidity increase in Florida: climate or sea-level?

Cited by 11 publications

References 29 publications

Sediment biomarkers elucidate the Holocene ontogeny of a shallow lake

Sediment biomarkers elucidate the Holocene ontogeny of a shallow lake

The Role of Paleoecology in Restoration and Resource Management—The Past As a Guide to Future Decision-Making: Review and Example from the Greater Everglades Ecosystem, U.S.A

Sensitivity of wetland hydrology to external climate forcing in central Florida

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