Pollen core assemblages as indicator of Polynesian and European impact on the vegetation cover of Auckland Isthmus catchment, New Zealand

Abrahim, Ghada M.S.; Parker, R. J.; Horrocks, Mark

doi:10.1016/j.ecss.2013.06.028

Cited by 3 publications

(7 citation statements)

References 31 publications

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“…µ-XRF identified a magnetic susceptibility spike, corresponding to a 1-mm tephra layer at 291.1cm down core. Tephras have been used in numerous studies as independent isochronous markers (Abrahim et al, 2013;Augustinus, Bleakley, Deng, Shane, & Cochran, 2008;Augustinus et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, an increase in magnitude and frequency of charcoal, an abrupt decline in forest pollen and shift to seral species, and changes in lithology due to catchment disturbance are generally strong pieces of evidence for anthropogenic influence (McGlone & Wilmshurst, 1999). Accordingly, these proxies have been used by numerous authors to identify Polynesian arrival in various parts of New Zealand (Abrahim, Parker, & Horrocks, 2013;McWethy et al, 2010;Augustinus, Reid, Anderson, Deng, & Horrocks, 2006;McGlone & Wilmshurst, 1999;Newnham, Lowe, McGlone, Wilmshurst, & Higham, 1998).…”

Section: Paleolimnological Evidence Of Human Arrivalmentioning

confidence: 99%

“…The appearance of pine pollen (Pinus spp.) has been used to identify the arrival of Europeans in lake and estuarine sediment records by many studies (Abrahim et al, 2013;McWethy et al, 2010;Augustinus et al, 2006;Page, Trustrum, & DeRose, 1994). Trodahl et al (2016) found a low abundance of pollen in the stratigraphic record of Lake Wairarapa, therefore palynological analysis could not be completed.…”

Section: Paleolimnological Evidence Of Human Arrivalmentioning

confidence: 99%

“…This provides a natural baseline against which to assess degradation and produces information that can be used to set targets for restoration. Paleolimnological methods are becoming recognised as an essential tool for evaluating lake health (Birks, 1996;Battarbee, 1999;Smol, 2008;Bennion & Battarbee, 2007;Battarbee et al, 2010b), and in New Zealand numerous studies have used these methods (Abrahim et al, 2013;McWethy et al, 2010;Augustinus et al, 2006;McGlone & Wilmshurst, 1999;Newnham et al, 1998). To investigate research question oneare algal blooms a natural feature of Lake Pounui -I will measure indicators of ecological change, catchment disturbance, and human arrival.…”

Section: Introductionmentioning

confidence: 99%

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Reconstructing Ecological Change, Catchment Disturbance, and Anthropogenic Impact over the last 3000 years at Lake Pounui, Wairarapa, New Zealand

Cochrane¹

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<p>Increased eutrophication of freshwater lakes has been attributed to an intensification in agriculture, with global warming projected to further compound the problem. Determining pre-human conditions of a lake has major conservation implications for water quality management, such as setting evidence-based restoration targets. New Zealand’s historical monitoring records of lake water quality are short and typically only begin after the onset of deterioration. Paleolimnology offers a complementary means of evaluating historical trends that predate human impact. This thesis investigates the declining water quality of Lake Pounui. Lake Pounui possesses high ecological integrity, though the lake is experiencing an increased frequency of severe algal blooms. The primary aim of this thesis is to reconstruct the past environment of Lake Pounui using paleolimnological methods to extend the historical monitoring data beyond human arrival. The reconstruction is used to address whether algal blooms are a natural feature of the lake, and examine anthropogenic impact. This study then attempts to identify reference conditions and critical transitions within the lake environment. Using this information possible targets for lake health restoration are discussed. Based on elevated charcoal influx, palynological evidence, and catchment disturbance indicators, such as organic content (Loss-on-Ignition (LOI)), grain size, and micro-X-ray fluorescence (µ-XRF), Māori land clearance was identified at ~450-350 calendar years before present (cal yr BP) (95% confidence interval (CI): 515.2-202.3 cal yr BP). The appearance of Pinus pollen and the diatom Asterionella formosa placed European arrival at ~150 cal yr BP (95% CI: 243-39 cal yr BP). Pre- and post-human environments of Lake Pounui were characterised using diatom analysis, bacterial DNA analysis, and supporting evidence from µ-XRF data. It appears that the lake existed in both a higher nutrient (3000-2100 cal yr BP, 95% CI: 3210-1977 cal yr BP) and lower nutrient (1600-450 cal yr BP, 95% CI: 1737- 389 cal yr BP) state, separated by a period of natural disturbance, which could relate to a combination of earthquakes and increased storminess. During Māori occupation (450-150 cal yr BP, 95% CI: 515-57 cal yr BP) the quality of the lake remained relatively high; however from 150 cal yr BP, the lake appears to become more nutrient enriched, and the cyanobacteria responsible for today’s blooms (Dolichospermum and Phormidium) become abundant. Paleolimnological analysis identified that the decline in water quality seen at Lake Pounui is a trend that has occurred over the last 200 years. Dissimilarity and critical transition analysis support this finding and suggest that rapid decline began just prior to 1950 AD. Based on dissimilarity analysis, the period of Māori occupation provides the most realistic restoration target. Planting native vegetation, ceasing stock grazing, and removing perch should be investigated to control the phytoplankton biomass, at the owner’s discretion.</p>

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Section: Methodsmentioning

confidence: 99%

Section: Paleolimnological Evidence Of Human Arrivalmentioning

confidence: 99%

Section: Paleolimnological Evidence Of Human Arrivalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reconstructing Ecological Change, Catchment Disturbance, and Anthropogenic Impact over the last 3000 years at Lake Pounui, Wairarapa, New Zealand

Cochrane¹

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“…Therefore, periods of intense burning likely indicate the presence of people on the landscape. These events are often reflected in abrupt increases in charcoal particle influx into lake basins, departing from low and irregular baselines (Newnham, Lowe, McGlone, et al, 1998;Wilmshurst et al, 2004;Ogden et al, 2006;Abrahim et al, 2013). At the same time, a sharp decrease in tall tree pollen is coeval with an increase in light-demanding shrubs, scrub, bracken and grassland pollen (Elliot et al, 1995;Ogden et al, 2003).…”

Section: Changing Landusementioning

confidence: 99%

A paleolimnological investigation of agricultural intensification, water quality and ecosystem change at Lake Nganoke, southern Wairarapa, NZ

Parrish¹

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<p>Decreasing water quality of lakes as a result of anthropogenic landuse and specifically agricultural intensification is well documented in New Zealand. However, monitoring records of lake health are typically short, only commencing once signs of lake deterioration are observed. The shortness of the instrumental record precludes a detailed understanding of the relationship between landuse change, lake ecosystem trajectories and the effectiveness of mitigation strategies such as riparian planting. Paleolimnological reconstruction from sediment cores has the potential to develop high-resolution time series that may extend lake monitoring centuries into the past. This thesis uses paleoenvironmental reconstruction to investigate lake ecosystem change and water quality in Lake Nganoke, Wairarapa, New Zealand as a result of landuse intensification. The primary aim of this thesis is to reconstruct the past environment of Lake Nganoke from a pre-human reference state to the current day to assess: 1) how increased nutrient fluxes associated with landuse intensification have impacted the lake ecosystem; and 2) the ability of riparian zones to buffer these fluxes. The reconstruction was achieved using a multi proxy approach with pre and post-human environments of Lake Nganoke characterised using Palynology, geochemistry, eDNA and hyperspectral scanning. Māori land clearance was identified at ~AD 1450 (95% CI: AD 1417-1551). The appearance of Pinus pollen and increases in fertilisation and stocking rates placed European arrival at ~AD 1850 (95% CI: 1809 - 1870), while intensification of agricultural landuse occurred post ~AD 1950 (95% CI: 1948 - 1964). The prehuman environment of Lake Nganoke experienced little change, with the catchment dominated by tall trees and likely heavily forested. The lake ecosystem and water quality during this time showed little to no change, with algal productivity likely driven by a constant input of natural nutrients. Post Māori arrival, algal productivity was reduced suggesting an increase in water quality likely driven by added lake marginal plants providing a riparian buffer to terrestrially derived nutrients. Lake productivity increased dramatically post European arrival ~AD 1850, coeval with an increase in sediment Cd, suggesting that fertilisation may have driven a decline in water quality. Further increases in fertilisation and stocking rates indicate additional agricultural nutrient fluxes entering Lake Nganoke in AD 1950 when agriculture intensified. Abundances in denitrifying Gammaproteobacteria indicate increases in nutrient loading while bloom forming Cyanobacteria peak ~AD 2000 before declining till present. Riparian planting following Māori arrival appears sufficient to buffer the lake against increased terrestrial nutrient fluxes associated with land clearing. However, a riparian zone that covers the majority of the catchment post European settlement was inadequate in altering the lake’s degrading ecosystem and water quality trajectory.</p>

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Pollen and phytoliths in archaeological features from North Island, New Zealand, reveal landscape disturbance and cultivation of Polynesian-introduced Cordyline cf. fruticosa (ti)

Horrocks

Bader²,

Simmons

et al. 2022

The Journal of Island and Coastal Archaeology

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Pollen core assemblages as indicator of Polynesian and European impact on the vegetation cover of Auckland Isthmus catchment, New Zealand

Cited by 3 publications

References 31 publications

Reconstructing Ecological Change, Catchment Disturbance, and Anthropogenic Impact over the last 3000 years at Lake Pounui, Wairarapa, New Zealand

Reconstructing Ecological Change, Catchment Disturbance, and Anthropogenic Impact over the last 3000 years at Lake Pounui, Wairarapa, New Zealand

A paleolimnological investigation of agricultural intensification, water quality and ecosystem change at Lake Nganoke, southern Wairarapa, NZ

Pollen and phytoliths in archaeological features from North Island, New Zealand, reveal landscape disturbance and cultivation of Polynesian-introduced Cordyline cf. fruticosa (ti)

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