The Effect of Epidermal Structures on Leaf Spectral Signatures of Ice Plants (Aizoaceae)

Heim, René H.J.; Jürgens, Norbert; Große‐Stoltenberg, André; Oldeland, Jens

doi:10.3390/rs71215862

Cited by 21 publications

(11 citation statements)

References 50 publications

(66 reference statements)

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“…Different epidermal structures can modify leaf absorbance [83,84]. Among others, such as epicuticular wax crystals promoting leaf glaucescence [85], the covering of the leaf surface by a dense trichome layer, or pubescence, is probably the most deeply studied [86,87].…”

Section: Increasing Leaf Reflectancementioning

confidence: 99%

Living in Drylands: Functional Adaptations of Trees and Shrubs to Cope with High Temperatures and Water Scarcity

Peguero‐Pina

Vilagrosa

Alonso-Forn

et al. 2020

Forests

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Plant functioning and survival in drylands are affected by the combination of high solar radiation, high temperatures, low relative humidity, and the scarcity of available water. Many ecophysiological studies have dealt with the adaptation of plants to cope with these stresses in hot deserts, which are the territories that have better evoked the idea of a dryland. Nevertheless, drylands can also be found in some other areas of the Earth that are under the Mediterranean-type climates, which imposes a strong aridity during summer. In this review, plant species from hot deserts and Mediterranean-type climates serve as examples for describing and analyzing the different responses of trees and shrubs to aridity in drylands, with special emphasis on the structural and functional adaptations of plants to avoid the negative effects of high temperatures under drought conditions. First, we analyze the adaptations of plants to reduce the input of energy by diminishing the absorbed solar radiation through (i) modifications of leaf angle and (ii) changes in leaf optical properties. Afterwards, we analyze several strategies that enhance the ability for heat dissipation through (i) leaf size reduction and changes in leaf shape (e.g., through lobed leaves), and (ii) increased transpiration rates (i.e., water-spender strategy), with negative consequences in terms of photosynthetic capacity and water consumption, respectively. Finally, we also discuss the alternative strategy showed by water-saver plants, a common drought resistance strategy in hot and dry environments that reduces water consumption at the expense of diminishing the ability for leaf cooling. In conclusion, trees and shrubs living in drylands have developed effective functional adaptations to cope with the combination of high temperature and water scarcity, all of them with clear benefits for plant functioning and survival, but also with different costs concerning water use, carbon gain, and/or leaf cooling.

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Section: Increasing Leaf Reflectancementioning

confidence: 99%

Living in Drylands: Functional Adaptations of Trees and Shrubs to Cope with High Temperatures and Water Scarcity

Peguero‐Pina

Vilagrosa

Alonso-Forn

et al. 2020

Forests

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“…PCA treats all variables equally, maximizes the variance of the features, and does not take into account the classification label associated with them. A supervised method, partial least squares discriminant analysis (PLS-DA) [68], was performed for the classification of canopy layers, trees, and cardinal directions. The key wavelengths that influence the reflectance of the leaves for the differences among the canopy layers (together for three trees) were identified using the variable importance in projection (VIP) [68] for the wavelength range from 482 to 2307 nm.…”

Section: Analysis and Classificationmentioning

confidence: 99%

Leaf Canopy Layers Affect Spectral Reflectance in Silver Birch

et al. 2019

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The availability of light within the tree canopy affects various leaf traits and leaf reflectance. We determined the leaf reflectance variation from 400 nm to 2500 nm among three canopy layers and cardinal directions of three genetically identical cloned silver birches growing at the same common garden site. The variation in the canopy layer was evident in the principal component analysis (PCA), and the influential wavelengths responsible for variation were identified using the variable importance in projection (VIP) based on partial least squares discriminant analysis (PLS-DA). Leaf traits, such as chlorophyll, nitrogen, dry weight, and specific leaf area (SLA), also showed significant variation among the canopy layers. We found a shift in the red edge inflection point (REIP) for the canopy layers. The canopy layers contribute to the variability in the reflectance indices. We conclude that the largest variation was among the canopy layers, whereas the differences among individual trees to the leaf reflectance were relatively small. This implies that within-tree variation due to the canopy layer should be taken into account in the estimation of intraspecific variation in the canopy reflectance.

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“…The plant probe's white reference disk was used as in [50]. In 2014, we additionally used black, foamed rubber as dark background (see [26]). The canopy spectra were taken with a field of view of 25˝ [52].…”

Section: Collection Of Field Spectramentioning

confidence: 99%

Evaluation of Continuous VNIR-SWIR Spectra versus Narrowband Hyperspectral Indices to Discriminate the Invasive Acacia longifolia within a Mediterranean Dune Ecosystem

et al. 2016

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Hyperspectral remote sensing is an effective tool to discriminate plant species, providing vast potential to trace plant invasions for ecological assessments. However, necessary baseline information for the use of remote sensing data is missing for many high-impact invaders. Furthermore, the identification of the suitable classification algorithms and spectral regions for successfully classifying species remains an open field of research. Here, we tested the separability of the invasive tree Acacia longifolia from adjacent exotic and native vegetation in a Natura 2000 protected Mediterranean dune ecosystem. We used continuous visible, near-infrared and short wave infrared (VNIR-SWIR) data as well as vegetation indices at the leaf and canopy level for classification, comparing five different classification algorithms. We were able to successfully distinguish A. longifolia from surrounding vegetation based on vegetation indices. At the leaf level, radial-basis function kernel Support Vector Machine (SVM) and Random Forest (RF) achieved both a high Sensitivity (SVM: 0.83, RF: 0.78) and a high Positive Predicted Value (PPV) (0.86, 0.83). At the canopy level, RF was the classifier with an optimal balance of Sensitivity (0.75) and PPV (0.75). The most relevant vegetation indices were linked to the biochemical parameters chlorophyll, water, nitrogen, and cellulose as well as vegetation cover, which is in line with biochemical and ecophysiological properties reported for A. longifolia. Our results highlight the potential to use remote sensing as a tool for an early detection of A. longifolia in Mediterranean coastal ecosystems.

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The Effect of Epidermal Structures on Leaf Spectral Signatures of Ice Plants (Aizoaceae)

Cited by 21 publications

References 50 publications

Living in Drylands: Functional Adaptations of Trees and Shrubs to Cope with High Temperatures and Water Scarcity

Living in Drylands: Functional Adaptations of Trees and Shrubs to Cope with High Temperatures and Water Scarcity

Leaf Canopy Layers Affect Spectral Reflectance in Silver Birch

Evaluation of Continuous VNIR-SWIR Spectra versus Narrowband Hyperspectral Indices to Discriminate the Invasive Acacia longifolia within a Mediterranean Dune Ecosystem

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