Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

Hartikainen, Saara M.; Jach, A; Grané, Aurea; Robson, T. Matthew

doi:10.1002/ece3.4496

Cited by 24 publications

(45 citation statements)

References 39 publications

(68 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Four "measurement points" approximately equidistance between the nearest trees were established in each stand. We considered this the minimum number of replicate patches required to describe small scale variation in irradiance (Hartikainen et al, 2018) and in the plant community in each stand, while remaining feasible to measure close to solar noon.…”

Section: Experimental Design and Description Of The Sitementioning

confidence: 99%

Seasonal Patterns in Spectral Irradiance and Leaf UV-A Absorbance Under Forest Canopies

et al. 2020

Self Cite

View full text Add to dashboard Cite

Plants commonly respond to UV radiation through the accumulation of flavonoids and related phenolic compounds which potentially ameliorate UV-damage to crucial internal structures. However, the seasonal dynamics of leaf flavonoids corresponding to epidermal UV absorbance is highly variable in nature, and it remains uncertain how environmental factors combine to govern flavonoid accumulation and degradation. We studied leaf UV-A absorbance of species composing the understorey plant community throughout two growing seasons under five adjacent tree canopies in southern Finland. We compared the relationship between leaf flavonol index (I flav -repeatedly measured with an optical leaf clip Dualex) and measured spectral irradiance, understorey and canopy phenology, air temperature and snowpack variables, whole leaf flavonoid extracts, and leaf age. Strong seasonal patterns and stand-related differences were apparent in I flav of both understorey plant communities and individual species, including divergent trends in I flav during spring and autumn. Comparing the heterogeneity of the understorey light environment and its spectral composition in looking for potential drivers of seasonal changes in I flav , we found that unweighted UV-A irradiance, or the effective UV dose calculated according to the biological spectral weighting function (BSWF) for plant growth (PG action spectrum), in understorey shade had a strong relationship with I flav . Furthermore, understorey species seemed to adjust I flav to low background diffuse irradiance rather than infrequent high direct-beam irradiance in sunflecks during summer, since leaves produced during or after canopy closure had low I flav . In conclusion, we found the level of epidermal flavonoids in forest understorey species to be plastic, adjusting to climatic conditions, and differing according to species' leaf retention strategy and new leaf production, all of which contribute to the seasonal trends in leaf flavonoids found within forest stands.

show abstract

Section: Experimental Design and Description Of The Sitementioning

confidence: 99%

Seasonal Patterns in Spectral Irradiance and Leaf UV-A Absorbance Under Forest Canopies

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Understory spectral irradiance in canopy shade during spring leaf out (25/04/2015). The measurements were taken in a deciduous B. pendula stand, following methods described in Hartikainen et al (2018). The different filter treatments are represented by line colours & types, whereby grey = ambient understory irradiance, black = transparent control filter, yellow = attenuation of UV radiation below 350nm, orange = attenuation of total UV radiation, and blue= attenuation of blue and UV radiation.…”

Section: Resultsmentioning

confidence: 99%

“…The effect of canopy closure on understory spectral composition in the stands was measured in 2015 (Hartikainen et al 2018), and during canopy leaf-out between April and June in 2016, 2017, and 2018. Spectral irradiance was recorded with a Maya 2000 Pro spectrometer (Ocean Optics, Dunedin, FL, USA) calibrated for accuracy in the solar UV and PAR regions of the spectrum.…”

Section: Methodsmentioning

confidence: 99%

“…Spectral irradiance was recorded with a Maya 2000 Pro spectrometer (Ocean Optics, Dunedin, FL, USA) calibrated for accuracy in the solar UV and PAR regions of the spectrum. The same device and protocol as Hartikainen et al (2018) were used for measurements and processing of the irradiance data. Ambient solar PAR above the canopy at Lammi Biological Station between 2015-2019 was also recorded to show the effects of changing cloudiness on incoming irradiance (PQS1 PAR Quantum Sensor, Kipp & Zonen, Delft, Netherlands, Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Once the canopy closes, the understory light environment is mostly shade (Chazdon and Pearcy, 1991). Not only does the amount of irradiance change in the understory, but so does its spectral composition, the light quality (Federer and Taner 1966, Vezina et al 1966, Ross and Flanagan 1986, Messier et al 1998, Leuchner et al 2005, Navrátil et al2007, Hartikainen et al 2018). Far-Red (FR) light is mostly reflected or transmitted from canopy leaf surfaces and scattered into the understory shade, reducing the ratio of red(R): FR light (Ballaré and Pierik 2017).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understory light quality affects leaf pigments and leaf phenology in different plant functional types

Brelsford

et al. 2019

Preprint

View full text Add to dashboard Cite

7Understory plant species take on different functional strategies, whereby some exploit periods 1 8 of available light in springtime before the canopy closes, and others also benefit from sunlight 1 9 later in autumn when the canopy opens again. These strategies involve understory species 2 0 coordinating phenological events to pre-empt canopy leaf out and to extend their growing 2 1 season beyond canopy leaf senescence, meanwhile accumulating photo-protective pigments 2 2 which mitigate periods of high-light exposure. Canopy closure brings shade to the understory, 2 3 but also causes drastic changes in light quality. Whilst many experiments manipulating spectral 2 4 quality have revealed understory plant responses to the changing R:FR ratio in shade, effect of 2 5 the blue and UV regions have been examined very little. We installed filters attenuating short 2 6 wavelength regions of the solar spectrum in a forest understory in southern Finland, creating the 2 7 following treatments: a transparent control filter, and filters attenuating UV radiation < 350 nm, 2 8 all UV radiation, and both UV and blue light. In eight understory species, representing different 2 9 plant functional types, we repeatedly assessed leaf optical properties to obtain epidermal 3 0 flavonol and anthocyanin contents from leaf emergence in spring to leaf senescence in autumn, 3 1 during both 2017 and 2018. Flavonols responded more to seasonal changes in light quality in 3 2 relatively light-demanding species than in shade-tolerant and wintergreen species; and were 3 3 particularly responsive to blue light. However, anthocyanins were largely unaffected by our 3 4 filter treatments, suggesting that other cues such as cold temperatures govern their seasonal 3 5 variation. UV radiation only accelerated leaf senescence in Acer platanoides seedlings, but blue 3 6 light accelerated leaf senescence in all species measured apart from Quercus robur. In 3 7 summary, seasonal changes in understory solar radiation in the blue and UV regions affected 3 8 leaf pigments and leaf phenology; particularly for more light-demanding species. An increase in 3 9 canopy duration under climate change will extend the period of shade in the understory, with 4 0 consequences for the spectral cues available to understory plants. The resultant reduction in 4 1 blue and UV radiation in shade, could delay leaf senescence in the understory even further. 4 2

show abstract

Solar UV-A radiation and blue light enhance tree leaf litter decomposition in a temperate forest

et al. 2019

View full text Add to dashboard Cite

Sunlight can accelerate the decomposition process through an ensemble of direct and indirect processes known as photodegradation. Although photodegradation is widely studied in arid environments, there have been few studies in temperate regions. This experiment investigated how exposure to solar radiation, and specifically UV-B, UV-A, and blue light, affects leaf litter decomposition under a temperate forest canopy in France. For this purpose, we employed custom-made litterbags built using filters that attenuated different regions of the solar spectrum. Litter mass loss and carbon to nitrogen (C:N) ratio of three species: European ash ( Fraxinus excelsior ), European beech ( Fagus sylvatica ) and pedunculate oak ( Quercus robur ), differing in their leaf traits and decomposition rate, were analysed over a period of 7–10 months. Over the entire period, the effect of treatments attenuating blue light and solar UV radiation on leaf litter decomposition was similar to that of our dark treatment, where litter lost 20–30% less mass and had a lower C:N ratio than under the full-spectrum treatment. Moreover, decomposition was affected more by the filter treatment than mesh size, which controlled access by mesofauna. The effect of filter treatment differed among the three species and appeared to depend on litter quality (and especially C:N), producing the greatest effect in recalcitrant litter ( F. sylvatica ). Even under the reduced irradiance found in the understorey of a temperate forest, UV radiation and blue light remain important in accelerating surface litter decomposition. Electronic supplementary material The online version of this article (10.1007/s00442-019-04478-x) contains supplementary material, which is available to authorized users.

show abstract

Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

Cited by 24 publications

References 39 publications

Seasonal Patterns in Spectral Irradiance and Leaf UV-A Absorbance Under Forest Canopies

Seasonal Patterns in Spectral Irradiance and Leaf UV-A Absorbance Under Forest Canopies

Understory light quality affects leaf pigments and leaf phenology in different plant functional types

Solar UV-A radiation and blue light enhance tree leaf litter decomposition in a temperate forest

Contact Info

Product

Resources

About