Remote sensing of the structural and spectral traits of vegetation is being transformed by structure from motion (SFM) algorithms that combine overlapping images to produce three-dimensional (3D) red-green-blue (RGB) point clouds. However, much remains unknown about how these point clouds are used to observe vegetation, limiting the understanding of the results and future applications. Here, we...

A growing number of studies have focused on evaluating vegetation indices in terms of their sensitivity to vegetation biophysical parameters as well as to external factors affecting canopy reflectance. In this context, leaf and canopy radiative transfer models have provided a basis for understanding the behaviour of such indices, particularly their resistance to external perturbing effects rela...

Phytophthora root rot (PRR) infects the roots of avocado trees, resulting in reduced uptake of water and nutrients, canopy decline, defoliation, and, eventually, tree mortality. Typically, the severity of PRR disease (proportion of canopy decline) is assessed by visually comparing the canopy health of infected trees to a standardised set of photographs and a corresponding disease rating. Althou...

In the past, obtaining reliable measurements of key forest canopy metrics has been difficult, even after the development of remote sensing technology. Fortunately, next-generation lidar systems are proving to be useful tools for deriving critical canopy measurements, such as height, structure and biomass. These studies have all focused on empirical comparisons between basic lidar-derived and fi...

In this paper, we evaluate the potential for extracting the “photochemical reflectance index” (PRI; previously called the “physiological reflectance index”) from AVIRIS data. This index, which is derived from narrow-band reflectanceat531 and 570 nm, has proven to be a useful indicator of photosynthetic function at the leaf and canopy scales (Gamon and Field 1992, Gamon et al. 1992, Pcfiuelas et...

The concept of canopy spectral invariants expresses the observation that simple algebraic combinations of leaf and canopy spectral reflectance become wavelength independent and determine two canopy structure specific variables – the recollision and escape probabilities. These variables specify an accurate relationship between the spectral response of a vegetation canopy to incident solar radiat...

Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate introduced species by altering resource availability. Here we examine how the presence of intact riparian cover influences the impact of an invasive herbivorous snail, Tarebia granifera, on...

The soil or background spectra contribution to grass canopy spectral reflectance for the 0.35 to 0.80 fJ-m region was investigated using in situ collected spectral reflectance data. Regression analysis was used to estimate accurately the unexposed soil spectral reflectance and to quantify maxima and minima for soil-green vegetation reflection contrasts. generally be impractical to take detailed...

We evaluated the initial 12 months of vegetation index product availability from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Earth Observing System-Terra platform. Two MODIS vegetation indices (VI), the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI), are produced at 1-km and 500-m resolutions and 16-day compositing periods. This pape...

The study shows that leaf area index (LAI) and canopy chlorophyll content can be mapped in a heterogeneous Mediterranean grassland from canopy spectral reflectance measurements. Canopy spectral measurements were made in the field using a GER 3700 spectroradiometer, along with concomitant in situ measurements of LAI and chlorophyll content. We tested the utility of univariate techniques, involvi...