Lichen Growth and Lichenometry

Armstrong, Richard A.

doi:10.1007/978-81-322-2181-4_10

Cited by 5 publications

(6 citation statements)

References 65 publications

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“…No lichens exist on burned sites, but almost 100% of plots in the unburned sites have lichens. Records show that the unburned sites have not had any major distur bances for few years so that the pre-fire vegetative structure on Wa’ahila Ridge was well established ( Armstrong 2015 , Merinero et al 2015 ). In the post-fire recovery phase, the first to third year after the fire played important roles in determining the probability of invasive or native tree, shrub, and grass recovery, contraction, or loss.…”

Section: Discussionmentioning

confidence: 99%

Vegetation and fire in lowland dry forest at Wa’ahila Ridge on O’ahu, Hawai’i

Lu¹,

DeLay²

2016

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Long-term ecological studies are critical for providing key insights in ecology, environmental change, natural resource management and biodiversity conservation. However, island fire ecology is poorly understood. No previous studies are available that analyze vegetative changes in burned and unburned dry forest remnants on Wa’ahila Ridge, Hawai’i. This study investigates vegetation succession from 2008 to 2015, following a fire in 2007 which caused significant differences in species richness, plant density, and the frequency of woody, herb, grass, and lichens between burned and unburned sites. These findings infer that introduced plants have better competitive ability to occupy open canopy lands than native plants after fire. This study also illustrates the essential management need to prevent alien plant invasion, and to restore the native vegetation in lowland areas of the Hawaiian Islands by removing invasive species out-planting native plants after fire.

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Section: Discussionmentioning

confidence: 99%

Vegetation and fire in lowland dry forest at Wa’ahila Ridge on O’ahu, Hawai’i

Lu¹,

DeLay²

2016

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“…However, few studies (e.g., Armstrong, 1983;Bradwell and Armstrong, 2007) have produced comprehensive growth curves considering growth as a function of diameter (Armstrong, 2015). This study presents the first such curve for the eastern Canadian Arctic, and the first set of curves produced within close proximity (b 20 km) at different elevations (range~375 m).…”

Section: Universal Lichen Growth Ratesmentioning

confidence: 99%

“…Typically, lichenometric dating of historical moraines uses the indirect approach where lichenometric field data is used in conjunction with known dates on local moraine surfaces to create a lichen size-age calibration curve used for dating (Armstrong, 2015). In contrast, the direct approach to lichenometric dating has been rarely employed owing to the relative lack of long-term measurements of lichen growth rates (Armstrong, 2014).…”

Section: Lichenometric Datamentioning

confidence: 99%

“…Given the paucity of surfaces with known ages in the Torngat Mountains, reliable calibration curves could not be constructed using the standard indirect technique. However, owing to the availability of historical photography of lichens at several growth stations established by McCoy (1983) and Rogerson et al (1986a,b), it was possible to create lichen growth curves using the direct method described in Armstrong (2014Armstrong ( , 2015. The direct method of lichen growth curve construction results in larger uncertainties relative to the indirect method because of the highly variable nature of shortterm growth rates displayed by crustose lichens (Armstrong, 2014;Roof and Werner, 2011).…”

Section: Lichenometric Datamentioning

confidence: 99%

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Glacier change from the early Little Ice Age to 2005 in the Torngat Mountains, northern Labrador, Canada

2015

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a b s t r a c tThe glaciers of the Torngat Mountains of northern Labrador are the southernmost of the Canadian Arctic and the easternmost of continental North America. Currently, 195 small mountain glaciers cover an area in excess of~24 km 2 , confined mostly to small cirques and upland depressions. Using a combination of field and remote sensing methods this study reconstructs and dates the areal extent of Torngat glaciers at their Neoglacial maximums, enabling the first assessment of regional glacier change over the past several centuries. Mapped glacier paleomargins (n = 165) are compared to current (2005) glaciers and ice masses, showing a 52.5% reduction in glacier area, with at least 11 former glaciers altogether disappearing. Glacier change is spatially homogenous and independent of most geographic and topographic factors; however, glacier elevation and glacier size mitigated total change. Previously established lichen growth stations were revisited, and growth rates recalculated based on~30-year-long records, enabling the construction of locally derived low-and high-altitude lichen growth curves. Using growth rates and in situ lichen measurements, the retreat from maximum Neoglacial moraine extents are suggested to have occurred between A.D. 1581 and 1673. These findings indicate a similar magnitude of post-LIA retreat to mountain glaciers elsewhere, yet a much earlier timing (~200 years) of retreat than other glaciers in the eastern Canadian Arctic. Though no definitive answer explaining this discrepancy is presented, evidence suggests that regional climate dynamics and the importance of solar radiation for Torngat glaciers may play an important role in local glacierization.

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“…Lifespan studies in lichens have mainly concerned epilithic species (Armstrong 2015), while data for corticolous species are available from only a limited number of studies (Phillips 1969; Snelgar & Green 1982). In our material, Lepraria incana (incl.…”

mentioning

confidence: 99%