scholarly journals Scaling Functional Traits from Leaves to Canopies

2020 ◽  
pp. 43-82 ◽  
Author(s):  
Shawn P. Serbin ◽  
Philip A. Townsend
Keyword(s):  
Functional Diversity ◽  
Functional Traits ◽  
Imaging Spectroscopy ◽  
Plant Functional Traits ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectroscopy Data ◽  
Sampling Protocols ◽  
History Of ◽  
The Relationship

AbstractIn this chapter, we begin by exploring the relationship between plant functional traits and functional diversity and how this relates to the characterization and monitoring of global plant biodiversity. We then discuss the connection between leaf functional traits and their resulting optical properties (i.e., reflectance, transmittance, and absorption) and how this related to remote sensing (RS) of functional diversity. Building on this, we briefly discuss the history of RS of functional traits using spectroscopy and imaging spectroscopy data. We include a discussion of the key considerations with the use of imaging spectroscopy data for scaling and mapping plant functional traits across diverse landscapes. From here we provide a review of the general methods for scaling and mapping functional traits, including empirical and radiative transfer model (RTM) approaches. We complete the chapter with a discussion of other key considerations, such as field sampling protocols, as well as current caveats and future opportunities.

scholarly journals Functional composition and diversity of leaf traits in subalpine versus alpine vegetation in the Apennines

AoB Plants ◽  
2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Angela Stanisci ◽  
Alessandro Bricca ◽  
Valentina Calabrese ◽  
Maurizio Cutini ◽  
Harald Pauli ◽  
...  
Keyword(s):  
Functional Diversity ◽  
Functional Traits ◽  
Resource Use ◽  
Leaf Traits ◽  
Growing Season ◽  
Plant Functional Traits ◽  
High Mountain ◽  
Maximum Height ◽  
Dry Matter Content ◽  
Functional Composition

Abstract Mediterranean high mountain grasslands are shaped by climatic stress and understanding their functional adaptations can contribute to better understanding ecosystems’ response to global change. The present work analyses the plant functional traits of high-elevation grasslands growing in Mediterranean limestone mountains to explore, at the community level, the presence of different plant strategies for resource use (conservative vs. acquisitive) and functional diversity syndromes (convergent or divergent). Thus, we compared the functional composition and diversity of the above-ground traits related to resource acquisition strategies of subalpine and alpine calcareous grasslands in the central Apennines, a mountain region characterized by a dry-summer Mediterranean climate. We used georeferenced vegetation plots and field-measured plant functional traits (plant maximum height, specific leaf area and leaf dry matter content) for the dominant species of two characteristic vegetation types: the subalpine Sesleria juncifolia community and the alpine Silene acaulis community. Both communities are of particular conservation concern and are rich in endemic species for which plant functional traits are measured here for the first time. We analysed the functional composition and diversity using the community-weighted mean trait index and the functional diversity using Rao’s function, and we assessed how much the observed pattern deviated from a random distribution by calculating the respective standardized effect sizes. The results highlighted that an acquisitive resource use strategy and relatively higher functional diversity of leaf traits prevail in the alpine S. acaulis community, optimizing a rapid carbon gain, which would help overcome the constraints exerted by the short growing season. The divergent functional strategy underlines the co-occurrence of different leaf traits in the alpine grasslands, which shows good adaptation to a microhabitat-rich environment. Conversely, in the subalpine S. juncifolia grassland, a conservative resource use strategy and relatively lower functional diversity of the leaf traits are likely related to a high level resistance to aridity over a longer growing season. Our outcomes indicate the preadaptation strategy of the subalpine S. juncifolia grassland to shift upwards to the alpine zone that will become warmer and drier as a result of anthropogenic climate change.

scholarly journals Snow Surface Albedo Sensitivity to Black Carbon: Radiative Transfer Modelling

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1077
Author(s):  
Nicholas D. Beres ◽  
Magín Lapuerta ◽  
Francisco Cereceda-Balic ◽  
Hans Moosmüller
Keyword(s):  
Radiative Transfer ◽  
Black Carbon ◽  
Surface Albedo ◽  
Mass Density ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Snow Surface ◽  
Snow Albedo ◽  
Carbon Mass ◽  
The Relationship

The broadband surface albedo of snow can greatly be reduced by the deposition of light-absorbing impurities, such as black carbon on or near its surface. Such a reduction increases the absorption of solar radiation and may initiate or accelerate snowmelt and snow albedo feedback. Coincident measurements of both black carbon concentration and broadband snow albedo may be difficult to obtain in field studies; however, using the relationship developed in this simple model sensitivity study, black carbon mass densities deposited can be estimated from changes in measured broadband snow albedo, and vice versa. Here, the relationship between the areal mass density of black carbon found near the snow surface to the amount of albedo reduction was investigated using the popular snow radiative transfer model Snow, Ice, and Aerosol Radiation (SNICAR). We found this relationship to be linear for realistic amounts of black carbon mass concentrations, such as those found in snow at remote locations. We applied this relationship to measurements of broadband albedo in the Chilean Andes to estimate how vehicular emissions contributed to black carbon (BC) deposition that was previously unquantified.

scholarly journals Quantifying the missing link between forest albedo and productivity in the boreal zone

2016 ◽  
Vol 13 (21) ◽  
pp. 6015-6030 ◽  
Author(s):  
Aarne Hovi ◽  
Jingjing Liang ◽  
Lauri Korhonen ◽  
Hideki Kobayashi ◽  
Miina Rautiainen
Keyword(s):  
Forest Management ◽  
Forest Floor ◽  
Basal Area ◽  
Shortwave Radiation ◽  
Coniferous Forests ◽  
Radiative Transfer Model ◽  
Radiation Balance ◽  
Transfer Model ◽  
Intensively Managed ◽  
The Relationship

Abstract. Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Currently, the physical link between forest albedo and productivity is poorly understood, yet it is crucial for designing optimal forest management strategies for mitigating climate change. We investigated the relationships between boreal forest structure, albedo and FAPAR using a radiative transfer model called Forest Reflectance and Transmittance model FRT and extensive forest inventory data sets ranging from southern boreal forests to the northern tree line in Finland and Alaska (N  =  1086 plots). The forests in the study areas vary widely in structure, species composition, and human interference, from intensively managed in Finland to natural growth in Alaska. We show that FAPAR of tree canopies (FAPARCAN) and albedo are tightly linked in boreal coniferous forests, but the relationship is weaker if the forest has broadleaved admixture, or if canopies have low leaf area and the composition of forest floor varies. Furthermore, the functional shape of the relationship between albedo and FAPARCAN depends on the angular distribution of incoming solar irradiance. We also show that forest floor can contribute to over 50 % of albedo or total ecosystem FAPAR. Based on our simulations, forest albedos can vary notably across the biome. Because of larger proportions of broadleaved trees, the studied plots in Alaska had higher albedo (0.141–0.184) than those in Finland (0.136–0.171) even though the albedo of pure coniferous forests was lower in Alaska. Our results reveal that variation in solar angle will need to be accounted for when evaluating climate effects of forest management in different latitudes. Furthermore, increasing the proportion of broadleaved trees in coniferous forests is the most important means of maximizing albedo without compromising productivity: based on our findings the potential of controlling forest density (i.e., basal area) to increase albedo may be limited compared to the effect of favoring broadleaved species.

scholarly journals Landscape context mediates the relationship between plant functional traits and decomposition

2019 ◽  
Vol 438 (1-2) ◽  
pp. 377-391 ◽  
Author(s):  
Marko J. Spasojevic ◽  
Katherine Harline ◽  
Claudia Stein ◽  
Scott A. Mangan ◽  
Jonathan A. Myers
Keyword(s):  
Functional Traits ◽  
Plant Functional Traits ◽  
Landscape Context ◽  
The Relationship

scholarly journals Monitoring spatial and temporal variations of surface albedo on Saint Sorlin Glacier (French Alps) using terrestrial photography

2011 ◽  
Vol 5 (1) ◽  
pp. 271-305
Author(s):  
M. Dumont ◽  
P. Sirguey ◽  
Y. Arnaud ◽  
D. Six
Keyword(s):  
Mass Balance ◽  
Near Infrared ◽  
Solar Spectrum ◽  
Incident Radiation ◽  
Temporal Variations ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Glacier Mass Balance ◽  
Infrared Wavelengths ◽  
The Relationship

Abstract. Accurate knowledge of temperate glacier mass balance is essential to understand the relationship between glacier and climate. Defined as the reflected fraction of incident radiation over the whole solar spectrum, the surface broadband albedo is one of the leading variable of their mass balance. This study presents a new method to retrieve the albedo of frozen surfaces from terrestrial photography at visible and near infrared wavelengths. This method accounts for the anisotropic reflectance of snow and ice surfaces and uses a radiative transfer model for narrow-to-broadband conversion. The accuracy of the method was assessed using concomitant measurements of albedo during the summers 2008 and 2009 on Saint Sorlin Glacier (Grandes Rousses, France). These albedo measurements are performed at two locations on the glacier, one in the ablation area and the other in the accumulation zone, with a net radiometer Kipp and Zonen CNR1. Main sources of uncertainty are associated with the presence of high clouds and the georeferencing of the photographs.

scholarly journals Quantifying the missing link between forest albedo and productivity in the boreal zone

2016 ◽  
Author(s):  
Aarne Hovi ◽  
Jingjing Liang ◽  
Lauri Korhonen ◽  
Hideki Kobayashi ◽  
Miina Rautiainen
Keyword(s):  
Forest Management ◽  
Forest Floor ◽  
Shortwave Radiation ◽  
Coniferous Forests ◽  
Radiative Transfer Model ◽  
Radiation Balance ◽  
Transfer Model ◽  
Intensively Managed ◽  
The Relationship ◽  
Solar Angle

Abstract. Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Currently, the physical link between forest albedo and productivity is poorly understood, yet it is crucial for designing optimal forest management strategies for mitigating climate change. We investigated the relationships between boreal forest structure, albedo and FAPAR using radiative transfer model FRT and extensive forest inventory data sets ranging from southern boreal forests to the northern tree line in Finland and Alaska (N = 1086 plots). The forests in the study areas vary widely in structure, species composition, and human interference, from intensively managed in Finland to natural growth in Alaska. We show that FAPAR of tree canopies (FAPARCAN) and albedo are tightly linked in boreal coniferous forests, but the relationship is weaker if the forest has broadleaved admixture, or if canopies have low leaf area and the composition of forest floor varies. Furthermore, the functional shape of the relationship between albedo and FAPARCAN depends on solar angle. We also show that forest floor can contribute to over 50 % of albedo or total ecosystem FAPAR. Based on our simulations, forest albedos vary notably across the biome. Because of larger proportion of broadleaved trees, the forests in Alaska have higher albedo (0.141–0.184) than those in Finland (0.136–0.171) even though the albedo of pure coniferous forests is lower in Alaska. Our results reveal that variation in solar angle will need to be accounted for when evaluating climate effects of forest management in different latitudes. Furthermore, increasing the proportion of broadleaved trees in coniferous forests is the most important means of maximizing albedo without compromising productivity: based on our findings the potential of controlling forest density (i.e., basal area) to increase albedo may be limited compared to the effect of favoring broadleaved species.

scholarly journals Analytical Relationship between Two-Band Spectral Vegetation Indices Measured at Multiple Sensors on a Parametric Representation of Soil Isoline Equations

2019 ◽  
Vol 11 (13) ◽  
pp. 1620 ◽  
Author(s):  
Kenta Taniguchi ◽  
Kenta Obata ◽  
Hiroki Yoshioka
Keyword(s):  
Vegetation Index ◽  
Vegetation Indices ◽  
Parametric Representation ◽  
Radiative Transfer Model ◽  
Analytical Relationship ◽  
Transfer Model ◽  
Multiple Sensors ◽  
Spectral Vegetation Indices ◽  
Relative Errors ◽  
The Relationship

Differences between the wavelength band specifications of distinct sensors introduce systematic differences into the values of a spectral vegetation index (VI). Such relative errors must be minimized algorithmically after data acquisition, based on a relationship between the measurements. This study introduces a technique for deriving the analytical relationship between the VIs from two sensors. The derivation proceeds using a parametric form of the soil isoline equations, which relate the reflectances of two different wavelengths. First, the derivation steps are explained conceptually. Next, the conceptual steps are cast in a practical derivation by assuming a general form of the two-band VI. Finally, the derived expressions are demonstrated numerically using a coupled leaf and canopy radiative transfer model. The results confirm that the derived expression reduced the original differences between the VI values obtained from the two sensors, indicating the validity of the derived expressions. The derived expressions and numerical results suggested that the relationship between the VIs measured at different wavelengths varied with the soil reflectance spectrum beneath the vegetation canopy. These results indicate that caution is required when retrieving intersensor VI relationships over regions consisting of soil surfaces having distinctive spectra.

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