David Riaño

David Riaño
University of California, Davis | UCD · Department of Land, Air and Water Resources

PhD in enviromental sciences

About

125
Publications
41,825
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6,227
Citations
Citations since 2017
17 Research Items
2799 Citations
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20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500

Publications

Publications (125)
Article
It is well documented that energy balance and other remote sensing-based evapotranspiration (ET) models face greater uncertainty over water-limited tree-grass ecosystems (TGEs), representing nearly 1/6th of the global land surface. Their dual vegetation strata, the grass dominated understory and tree dominated overstory, make for distinct structura...
Article
Full-text available
Fuel moisture content (FMC) of live vegetation is a crucial wildfire risk and spread rate driver. This study presents the first daily FMC product at a global scale and 500 m pixel resolution from the Moderate Resolution Imaging Spectroradiometer (MODIS) and radiative transfer models (RTMs) inversion techniques. Firstly, multi-source information par...
Article
Many satellite missions rely on modeling approaches to acquire global or regional evapotranspiration (ET) products. However, a current challenge in ET modeling lies in dealing with sub-pixel heterogeneity, as models often assume homogeneous conditions at the pixel level. This is particularly an issue for heterogeneous landscapes , such as tree-gras...
Article
Providing accurate information on fire effects is critical to understanding post-fire ecological processes and to design appropriate land management strategies. Multispectral imagery from optical passive sensors is commonly used to estimate fire damage, yet this type of data is only sensitive to the effects in the upper canopy. This paper evaluates...
Article
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p>Mixed vegetation systems such as wood pastures and shrubby pastures are vital for extensive and sustainable livestock production as well as for the conservation of biodiversity and provision of ecosystem services, and are mostly located in areas that are expected to be more strongly affected by climate change. However, the structural characterist...
Article
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Live Fuel Moisture Content (LFMC) contributes to fire danger and behavior, as it affects fire ignition and propagation. This paper presents a two layered Landsat LFMC product based on topographically corrected relative Spectral Indices (SI) over a 2000-2011 time series, which can be integrated into fire behavior simulation models. Nine chaparral sa...
Article
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This paper develops an algorithm to estimate vegetation canopy gap fraction (GF), taking advantage of the full Terrestrial Laser Scanner (TLS) resolution. After calculating the TLS angular resolution, the algorithm identifies the missing laser hits (gaps) within an angular grid in the azimuthal and zenithal directions. The algorithm was first teste...
Article
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The thermal-based two-source energy balance (TSEB) model has accurately simulated energy fluxes in a wide range of landscapes with both remote and proximal sensing data. However, tree-grass ecosystems (TGE) have notably complex heterogeneous vegetation mixtures and dynamic phenological characteristics presenting clear challenges to earth observatio...
Article
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
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The thermal-based Two-Source Energy Balance (TSEB) model has successfully simulated energy fluxes in a wide range of landscapes. However, tree-grass ecosystems (TGE) have notably complex heterogenous vegetation mixtures and dynamic phenological characteristics presenting clear challenges to earth observation and modeling methods. Therefore, the TSE...
Article
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Globe-LFMC is an extensive global database of live fuel moisture content (LFMC) measured from 1,383 sampling sites in 11 countries: Argentina, Australia, China, France, Italy, Senegal, Spain, South Africa, Tunisia, United Kingdom and the United States of America. The database contains 161,717 individual records based on in situ destructive samples...
Article
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Alaska’s boreal region stores large amounts of carbon both in its woodlands and in the grounds that sustain them. Any alteration to the fire system that has naturally regulated the region’s ecology for centuries poses a concern regarding global climate change. Satellite-based remote sensors are key to analyzing those spatial and temporal patterns o...
Article
Fuel types are one of the key variables that drive wildfire ignition and propagation. A new method is proposed to automatically classify and map fuel types from LiDAR data. The 3-dimensional Discrete Anisotropic Radiative Transfer (DART) model generated a fuel type LiDAR signature library. These simulations provided reference endmembers and additio...
Article
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The 3-D Radiative Transfer Model (RTM) FLIGHT can represent scattering in open forest or savannas featuring underlying bare soils. However, FLIGHT might not be suitable for multilayered tree-grass ecosystems (TGE), where a grass understory can dominate the reflectance factor (RF) dynamics due to strong seasonal variability and low tree fractional c...
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A Bayesian classifier mapped the Burned Area (BA) in the Northeastern Siberian boreal forest (70°N 120°E–60°N 170°E) from 1982 to 2015. The algorithm selected the 0.05° (~5 km) Long-Term Data Record (LTDR) version 3 and 4 data sets to generate 10-day BA composites. Landsat-TM scenes of the entire study site in 2002, 2010, and 2011 assessed the spat...
Conference Paper
Full-text available
Resumen: Se ha desarrollado un algoritmo basado en un clasificador bayesiano (BA) para cartografiar áreas quemadas en regiones boreales a partir de imágenes diarias de satélite. El algoritmo se aplicó a la región nororiental de Siberia (70°N 120°E – 60°N 170°E) utilizando el conjunto de datos Long Term Data Record (LTDR) de resolución espacial de 0...
Article
The development of tower-mounted automated multi-angular hyperspectral systems has brought new opportunities and challenges for the characterization of the Bidirectional Reflectance Distribution Function (BRDF) on a continuous basis. This study describes the deployment of one of these systems in a Mediterranean savanna ecosystem (AMSPEC-MED), and p...
Article
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The socio-economic factors are of key importance during all phases of wildfire management that include prevention, suppression and restoration. However, modeling these factors, at the proper spatial and temporal scale to understand fire regimes is still challenging. This study analyses socio-economic drivers of wildfire occurrence in central Spain....
Data
Socio-economic dataset. S1 File contains data on the independent and dependent variables used for the analysis for the study periods (1980s and 2000s) by 1*1 km grid cell. (XLS)
Article
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The absorption features of liquid water in plant leaves are readily detectable, and the amount of leaf water content may be determined by spectroscopy. Spectral reflectances at about 1240 and 1650 nm are the basis of numerous remote-sensing indices that could be used to estimate liquid water content of leaves and canopies. Two applications of remot...
Article
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We have developed a methodology for detection of observable phenomena at pixel level over time series of daily satellite images, based on using a Bayesian classifier. This methodology has been applied successfully to detect burned areas in the North American boreal forests using the LTDR dataset. The LTDR dataset represents the longest time series...
Article
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Land Surface Temperature (LST) is one of the key inputs for Soil-Vegetation-Atmosphere transfer modeling in terrestrial ecosystems. In the frame of BIOSPEC (Linking spectral information at different spatial scales with biophysical parameters of Mediterranean vegetation in the context of global change) and FLUXPEC (Monitoring changes in water and ca...
Chapter
Forest fire management requires accurate, spatially explicit and up-to date information on forest fuels and their vertical structure. Airborne laser scanning (ALS) provides 3-D vegetation models to map accurate fuel properties critical for modelling fire behaviour. Laser point cloud data stratified into height intervals coupled with spectral inform...
Article
The direct estimation of nitrogen (N) in fresh vegetation is challenging due to its weak influence on leaf reflectance and the overlaps with absorption features of other compounds. Different empirical models relate in this work leaf nitrogen concentration ([N]Leaf) on Holm oak to leaf reflectance as well as derived spectral indices such as normaliz...
Chapter
The objective of this experiment was to investigate the suitability of airborne spectral reflectance for detection of plant canopy water status and its potential use as a tool for precision irrigation management of table grapes. The experiment took place in 2011 and 2012 in a table grape vineyard in Delano, CA, USA. Two deficit irrigation treatment...
Article
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This paper validates different MODIS products using in situ field measurements. To this end, a temporal series of normalized difference vegetation index (NDVI, MOD/MYD13Q1), leaf area index (LAI, MOD/MYD/MCD15A2) and gross primary productivity (GPP, MOD/MY17A2) products acquired between 2009 and 2011 are analysed.The study area is located in a “deh...
Conference Paper
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Quantification of states and rates of water content in vegetation is critical in plant ecology. This work aims to assess the performance of a wide range of methodologies for the retrieval of vegetation biochemical and biophysical properties related to water, including: (i) foliar water content (FWC, cm), (ii) canopy water content (CWC, cm), (iii) f...
Article
We have developed a pixel level methodology for observable phenomena detection in time series of daily satellite images. It consists of several steps: pre-processing, construction of the statistical variables space for a Bayesian classifier, algorithm design, obtaining probability maps and postprocessing. It has been designed a software tool to app...
Article
Full-text available
Canopy water content is a dynamic quantity that depends on the balance between water losses from transpiration and water uptake from the soil. Absorption of short-wave radiation by water is determined by various frequencies that match overtones of fundamental bending and stretching molecular transitions. Leaf water potential and relative water cont...
Article
Live fuel moisture (LFM) is an important fuel property controlling fuel ignition and fire propagation. LFM varies seasonally, and is controlled by precipitation, soil moisture, evapotranspiration, and plant physiology. LFM is typically sampled manually in the field, which leads to sparse measurements in space and time. Use of LFM proxies could redu...
Article
Greenberg, Jonathan Asher, Erin L. Hestir, David Riano, George J. Scheer, and Susan L. Ustin, 2012. Using LiDAR Data Analysis to Estimate Changes in Insolation Under Large-Scale Riparian Deforestation. Journal of the American Water Resources Association (JAWRA) 48(5): 939-948. DOI: 10.1111/j.1752-1688.2012.00664.x Abstract: Riparian vegetation prov...
Article
Improved estimates of evapotranspiration (ET) are needed for water resource management and irrigation scheduling. We review the use of imaging spectroscopy to capture estimates of water vapour flux and biophysical components of ET. Remote sensing has long attempted to quantify and predict ET, with most applications relying only on green vegetation...
Conference Paper
Full-text available
Holm oak Leaf Nitrogen Content (LNC) has been estimated in a Mediterranean savanna ecosystem "dehesa" in the Iberian Peninsula using an ASD FieldSpec° FR3 spectroradiometer connected to a Plant Probe with Leaf Clip (www.asdi.com). One of each ten bands between 400nm and 2500nm were selected, and two different Three Bands Indexes (TBI) with all the...
Conference Paper
For the study presented, we are assessing the impacts of a changing climate on tundra fire and the implications of increased fire on tundra ecosystem services vulnerable to changing fire regimes. We are investigating the influence of climate change in the Arctic on fire occurrence and fire effects in the tundra ecoregions of North America (NA) and...
Article
A synthesis was carried out to analyze information available to quantify fire activity and burned area across North America, including a comparison of different data sources and an assessment of how variations in burned area estimate impact carbon emissions from fires. Data sets maintained by fire management agencies provide the longest record of b...
Article
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Carrara discuss how their work is delivering vital information to help improve understanding of global climate change trends Building an ecosystem-focused knowledge base Can you describe the most relevant methodological components of Biospec? PM: Biospec is organised around three multi-scale activities: data generation, model calibration and valida...
Article
Vegetation canopy water content (CWC) is an important parameter for monitoring natural and agricultural ecosystems. Previous studies focused on the observation of annual or monthly variations in CWC but lacked temporal details to study vegetation physiological activities within a diurnal cycle. This study provides an evaluation of detecting vegetat...
Article
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This paper evaluates the potential of a terrestrial laser scanner (TLS) to characterize forest canopy fuel characteristics at plot level. Several canopy properties, namely canopy height, canopy cover, canopy base height and fuel strata gap were estimated. Different approaches were tested to avoid the effect of canopy shadowing on canopy height esti...
Article
This article explores the potential use of remote sensing to discriminate two grassweeds (Avena sterilis and Lolium rigidum) from four cultivars (cvs) of winter wheat and barley. Hyperspectral measurements, using a GER2600 spectroradiometer (350 to 2500 nm), were conducted throughout the life cycle of the plants in order to analyse spectral differe...
Conference Paper
The Sacramento-San Joaquin Delta has approximately 1,100 miles of levees, which supports agriculture, maintains water exports and protects urban areas and infrastructures. The integrity of these levees is of major importance to land managers and policy makers given the consequence of levee failure. External evidence of levee instability such as slu...
Conference Paper
Full-text available
This work was aimed at investigating the effectiveness of genetic algorithms (GA) - partial least square (PLS) regression in estimation of canopy equivalent water thickness (EWT) from MODIS image data of the SMEX'04 site. Calibration of MODIS spectral variables (single bands, band ratios and curvatures) against the AVIRIS-derived EWT at a degraded...
Article
Biomass fractions (total aboveground, branches and foliage) were estimated from a small footprint discrete-return LiDAR system in an unmanaged Mediterranean forest in central Spain. Several biomass estimation models based on LiDAR height, intensity or height combined with intensity data were explored. Raw intensity data were normalized to a standar...
Article
Full-text available
The long-term data record (LTDR) project funded by the National Aeronautics and Space Administration has created a global daily data set at 0.05deg spatial resolution, approximately 5 km, for environmental science applications. The LTDR uses observations from the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution R...
Conference Paper
Full-text available
Hyperspectral remote sensing techniques were used to map weeds found in corn crops, namely Sorghum halepense, Xanthium strumarium and Abutilon theophrasti. The image used was acquired by the AHS (Airborne Hyperspectral Scanner) at a 2.5m ground resolution and a total of 80 spectral band s ranging from 0.43 to 12.5 microns. The study area was a grou...
Chapter
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A review of physical and chemical properties of fuels relevant for fire ignition and propagation is presented, along with different methods to estimate those properties, with special emphasis on satellite imagery. The discussion is more extended on estimating fuel moisture trends and fuel geometrical properties.
Chapter
California ecosystems and climate have characteristics that promote to wildfire, particularly in the dry late summer and fall seasons. Over recent decades, fire severity and number of fires has increased. In many cases, the changing fire regimes have been concurrent with the spread of invasive annual grasses into shrub and woodland habitats that pr...
Article
Full-text available
Wildfires have major effects on forest dynamics, succession and the carbon cycle in the boreal biome. They are a significant source of carbon emissions, and current observed changes in wildfire regimes due to changes in climate could affect the balance of the boreal carbon pool. A better understanding of postwildfire vegetation dynamics in boreal f...
Article
This study aimed to investigate the performance of genetic algorithms coupled with partial least squares (GA-PLS) modeling of spectral reflectance in retrieving equivalent water thickness (EWT) at leaf and canopy level. A genetic algorithm was used to identify a subset of spectral bands sensitive to the variation in EWT, and PLS was then applied to...
Article
Full-text available
Disturbance events such as fire have major effects on forest dynamics, succession and the carbon cycle in the boreal biome. This paper focuses on establishing whether characteristic spatio‐temporal patterns of the fraction of Absorbed Photosynthetically Active Radiation (fAPAR) occur in the initial two years after a fire event in Siberian boreal fo...
Article
Vegetation water stress drives wildfire behavior and risk, having important implications for biogeochemical cycling in natural ecosystems, agriculture, and forestry. Water stress limits plant transpiration and carbon gain. The regulation of photosynthesis creates close linkages between the carbon, water, and energy cycles and through metabolism to...
Article
Full-text available
LiDAR (Light Detection and Ranging) data have shown a great potential for 3D modelling applications. This potential lies on the ability of LiDAR systems to generate highly dense 3D point clouds for describing the terrain surface. Several error sources affect the position accuracy of the 3D points, which are represented as offsets between the overla...
Article
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As valuation of ecosystem goods and services derived from ecological processes becomes increasingly important in environmental decision-making, the need to quantify how restoration activities influence ecosystem function has grown more urgent, particularly within income-generating or subsistence-providing landscapes where economic needs and biodive...
Article
This paper presents a method to estimate fuel moisture content (FMC) of Mediterranean vegetation species from satellite images in the context of fire risk assessment. The relationship between satellite images and field collected FMC data was based on two methodologies: empirical relations and statistical models based on simulated reflectances deriv...
Article
Hyperspectral water retrievals from AVIRIS data, equivalent water thickness (EWT), were compared to in situ leaf water content and LAI measurements at a semiarid site in southeastern Arizona. Retrievals of EWT showed good correlation with field canopy water content measurements. Statistical analysis suggested that EWT was significantly different am...
Article
An inversion of linked radiative transfer models (RTM) through artificial neural networks (ANN) was applied to MODIS data to retrieve vegetation canopy water content (CWC). The estimates were calibrated and validated using water retrievals from AVIRIS data from study sites located around the United States that included a wide range of environmental...
Article
Full-text available
Traditional field-based methods for estimating burn severity are time-consuming, labour intensive and normally limited in spatial extent. Remotely sensed data provide a means to estimate severity levels across large areas, but it is critical to understand the causes of variability in spectral response with va- riations in burn severity. Since exper...
Conference Paper
Full-text available
Boreal forests comprise one third of global forested area and are the largest terrestrial carbon store. Forest fires are the regions most dynamic disturbance factor, occurring mainly in Siberia, Russian Far East, Canada and Alaska, and these fires represent a globally important release of terrestrial carbon to the atmosphere, via the burning of veg...