Advantages of visible-band spectral remote sensing at both satellite and near-surface scales for monitoring the seasonal dynamics of GPP in a Japanese larch forest

Abstract

Remotely sensed vegetation indices such as the normalized difference vegetation index (NDVI) or enhanced vegetation index (EVI) have been used to scale up flux-based gross primary production (GPP) measurements. Recently, the use of visible-band (VIS) indices for estimation of GPP has been proposed, and VIS_indices derived from digital cameras have been used for detecting phenological changes. To confirm the utility of remotely sensed VIS_indices for the evaluation of GPP in a Japanese larch forest, we investigated the relationships between flux-based GPP measurements and indices derived from both moderate resolution imaging spectroradiometer (MODIS) data and tower-mounted digital camera images. We evaluated the suitability of both traditional (NDVI and EVI) and VIS_indices (the greenred vegetation index (GRVI) and green ratio (GR)) at both satellite and near-surface scales for GPP estimation. We also used the MODIS data to evaluate the sensitivity of the indices to the effects of a severe forest disturbance. The results showed that VIS_indices had several advantages over the traditional indices: (1) seasonal variations in VIS_indices were more strongly correlated with GPP variations; (2) the vegetation growing season could be easily discriminated from the winter dormant period, because ground surface conditions affect VIS_indices less than they affect traditional indices; (3) the seasonal dynamics of vegetation could be determined at a satellite scale from MODIS data, and possibly even at a canopy scale from digital camera images; and (4) inter-annual variations of VIS_indices were likely to be more sensitive to vegetation changes after a disturbance. These results demonstrate the utility of VIS_indices for estimating GPP at satellite scales and possibly at the canopy scale. We suggest that multi-scale visible-band remote sensing could help our understanding of the ecosystem by improving the temporal and spatial resolutions of satellite data.

The relationship between carbon dioxide uptake and canopy colour from two camera systems in a deciduous forest in southern England

“…At some study sites, the peak of S green coincided with the GPP peak (e.g. Ide et al 2011;Migliavacca et al 2011), but in others, as here, GPP lagged behind the peak of S green (e.g. Ahrends et al 2009;this study).…”

“…Ide et al . ; Migliavacca et al . ), but in others, as here, GPP lagged behind the peak of S green (e.g.…”

Upscaling terrestrial carbon dioxide fluxes in Alaska with satellite remote sensing and support vector regression

“…For example, many land surfaces (e.g., snow, soil, autumn color of leaves, and defoliated trees) have a similar minimum value of GR, which helped to distinguish the vegetation growing period from the dormant period [ Ide et al ., ]. Recently, the advantage of GR in predicting seasonal and interannual variations of GPP was also reported in several ecosystems [ Ahrends et al ., ; Harazono et al ., ; Ide et al ., ]. Further site‐level studies using GR could improve CO 2 flux estimation in Arctic ecosystems.…”

Review: Development of an in situ observation network for terrestrial ecological remote sensing: the Phenological Eyes Network (PEN)

“…Mizunuma et al (2013) showed that HUE corresponded well with the GPP data collected at the AHS site. Ide et al (2011) showed that the GR and GRVI, both of which were derived from ADFC images, corresponded well with GPP at the TMK site.…”

“…In 2004, a large typhoon hit the TMK site, felling most of the trees. Ide et al (2011) showed that this large disturbance was detected more clearly by the GRVI than by the NDVI, the green-to-red ratio (GR), or the Enhanced Vegetation Index (EVI). Nagai et al (2012) showed that the GRVI could detect the phenology of evergreen trees, whereas the EVI and NDVI were insensitive.…”