Impacts of forestry planting on primary production in upland lakes from north‐west Ireland

Stevenson, Mark A.; McGowan, Suzanne; Anderson, Nicholas; Foy, R. H.; Leavitt, Peter R.; McElarney, Y.; Engstrom, Daniel R.; Pla‐Rabès, Sergi

doi:10.1111/gcb.13194

Cited by 9 publications

(6 citation statements)

References 102 publications

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“…We infer that reduced UVR exposure arose from progressive, but slightly asynchronous, eutrophication of both lakes, as declines in lake level should have increased mean UVR exposure. Similar declines in UVR exposure are recorded elsewhere in lakes undergoing cultural eutrophication (Stevenson et al 2016).…”

Section: Discussionsupporting

confidence: 83%

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20^th century

Bjorndahl

Gushulak

Mezzini

et al. 2022

Limnology & Oceanography

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Climate-induced variation in lake level can affect physicochemical properties of endorheic lakes, but its consequences for phototrophic production and regime shifts are not well understood. Here, we quantified changes in the abundance and community composition of phototrophs in Kenosee and White Bear lakes, two endorheic basins in the parkland Moose Mountain uplands of southeastern Saskatchewan, Canada, which have experienced > 8 m declines in water level since $ 1900. We hypothesized that lower water levels and warmer temperatures should manifest as increased abundance of phytoplankton, particularly cyanobacteria, and possibly trigger a regime shift to turbid conditions due to evaporative concentration of nutrients and solutes. High-resolution analysis of sedimentary pigments revealed an increase in total phototrophic abundance (as β-carotene) concurrent with lake-level decline beginning $ 1930, but demonstrated little directional change in cyanobacteria. Instead, significant increases in obligately anaerobic purple sulfur bacteria (as okenone) occurred in both lakes during $ 1930-1950, coeval with alterations to light environments and declines in lake level. The presence of okenone suggests that climate-induced increases in solute concentrations may have favored the formation of novel bacterial habitats where photic and anoxic zones overlapped. Generalized additive models showed that establishment of this unique habitat was likely preceded by increased temporal variance of sulfur bacteria, but not phytoplankton or cyanobacteria, suggesting that this abrupt change to physical lake structure was unique to deepwater environments. Such climate-induced shifts may become more frequent in the region due to hydrological stress on lake levels due to warming temperatures across the Northern Great Plains.

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Section: Discussionsupporting

confidence: 83%

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20^th century

Bjorndahl

Gushulak

Mezzini

et al. 2022

Limnology & Oceanography

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“…Furthermore, canthaxanthin, an indicator of Nostocales cyanobacteria, is often associated with high nutrients in the water column (Kleppel et al, 1988;Lami et al, 2009), and can also be a marker of N 2 fixation (Hayes et al, in press). One possibility is that the Modern Period experienced in an influx of dissolved organic matter (DOM) which may have stimulated heterotrophic growth of the cyanobacterial groups (Stevenson et al, 2016). Regardless, it seems likely that factors other than climate must be considered to understand how limnological conditions became ideal for these groups in the Modern Period.…”

Section: Lake and Algal Responses To Holocene Climate Changementioning

confidence: 99%

Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

et al. 2019

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Historical changes in Holocene climate in northeastern Ontario were quantified using analyses of sedimentary pollen, diatoms, and pigments in a small boreal lake. Modern analog reconstructions of average temperature from Holocene pollen assemblages of Charland Lake showed temperature was ~2°C warmer than present conditions ~7800–4500 cal. yr BP, a time period consistent with the Holocene thermal maximum (HTM). Pollen data suggest a two-phase HTM: warm and dry conditions based on the presence of primarily Pinus spp., followed by warm and wet conditions based on increases in cedar. Overall, algal production was low during the HTM, as reflected by low concentrations of pigments and diatoms. In the late HTM, increases in cedar pollen and planktonic diatoms suggest sustained increases in water levels for the remainder of the Holocene. During the Post-HTM Period (~4500–2000 cal. yr BP), a period that was warmer than today but cooler than the HTM, overall pigment production was significantly higher than all other periods. However, changes in diatom species composition suggest this period was not uniform, with variation occurring between diatoms indicative of higher and lower nutrient levels. The last ~2000 cal. yr BP was less productive than the Post-HTM Period but more productive than the HTM with higher production from diatoms and cyanobacteria. This study suggests that the relationship between climate and lake water production can be quite complex, and that changes in temperature, precipitation, light, lake levels, and mixing patterns are among factors that are related to changes in subfossil phototroph assemblages.

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“…To provide a range of regime shift time series, we cross-examined the published literature and identified core records with (1) an abrupt onset of a eutrophic state (Roxton Pond; echinenone pigment used as a proxy of total cyanobacteria abundance; Vermaire et al 2017); (2) a noisier eutrophication signal (Lake Anarry; myxoxanthophyll pigment used as a proxy of colonial cyanobacteria abundance; Stevenson et al 2016);and (3) possible flickering between alternate states (Lake Geneva; a composite proxy reconstructed from multiple intercorrelated varved cores tracking the inferred volume of hypolimnetic hypoxia; Jenny et al 2014). Cyanobacterial dominance and hypolimnetic hypoxia are wellestablished symptoms of anthropogenic disturbances and increased nutrient loading to lakes (Edmondson 1961, Reckhow 1977; thus, both paleolimnological proxies are used here as indicators of a shift from oligotrophic to eutrophic conditions (Taranu et al 2015, Jenny et al 2016).…”

Section: Observed Lake Sediment Recordsmentioning

confidence: 99%

“…According to the paleolimnological record, this was followed by a change in the zooplankton and phytoplankton community and an increase in cyanobacterial pigment concentrations in the 1990s. Lake Anarry is an upland, shallow lake (maximum depth 7.8 m) situated in northwest Ireland, whose catchment was afforested in the 1960s (Stevenson et al 2016). Forest plantations accounted for >50% of the lake's catchment area.…”

Section: Observed Lake Sediment Recordsmentioning

confidence: 99%

Can we detect ecosystem critical transitions and signals of changing resilience from paleo‐ecological records?

et al. 2018

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Nonlinear responses to changing external pressures are increasingly studied in real-world ecosystems. However, as many of the changes observed by ecologists extend beyond the monitoring record, the occurrence of critical transitions, where the system is pushed from one equilibrium state to another, remains difficult to detect. Paleo-ecological records thus represent a unique opportunity to expand our temporal perspective to consider regime shifts and critical transitions, and whether such events are the exception rather than the rule. Yet, sediment core records can be affected by their own biases, such as sediment mixing or compression, with unknown consequences for the statistics commonly used to assess regime shifts, resilience, or critical transitions. To address this shortcoming, we developed a protocol to simulate paleolimnological records undergoing regime shifts or critical transitions to alternate states and tested, using both simulated and real core records, how mixing and compression affected our ability to detect past abrupt shifts. The smoothing that is built into paleolimnological data sets apparently interfered with the signal of rolling window indicators, especially autocorrelation. We thus turned to time-varying autoregressions (online dynamic linear models, DLMs; and time-varying autoregressive state-space models, TVARSS) to evaluate the possibility of detecting regime shifts and critical transitions in simulated and real core records. For the real cores, we examined both varved (annually laminated sediments) and nonvarved cores, as the former have limited mixing issues. Our results show that state-space models can be used to detect regime shifts and critical transitions in some paleolimnological data, especially when the signal-to-noise ratio is strong. However, if the records are noisy, the online DLM and TVARSS have limitations for detecting critical transitions in sediment records.

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Impacts of forestry planting on primary production in upland lakes from north‐west Ireland

Cited by 9 publications

References 102 publications

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20^th century

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20^th century

Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

Can we detect ecosystem critical transitions and signals of changing resilience from paleo‐ecological records?

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Impacts of forestry planting on primary production in upland lakes from north‐west Ireland

Cited by 9 publications

References 102 publications

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20th century

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20th century

Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

Can we detect ecosystem critical transitions and signals of changing resilience from paleo‐ecological records?

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Product

Resources

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Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20^th century

Abrupt changes in the physical and biological structure of endorheic upland lakes due to 8‐m lake‐level variation during the 20^th century