Daily GPP estimates in Mediterranean ecosystems by combining remote sensing and meteorological data

Gilabert, María Amparo; Moreno, A.; Maselli, Fabio; Martínez, Beatriz; Chiesi, Marta; Sánchez-Ruíz, Sergio; Garcı́a-Haro, Francisco Javier; Pérez-Hoyos, Ana; Campos-Taberner, Manuel; Pérez-Priego, Óscar; Serrano-Ortiz, Penélope; Carrara, Arnaud

doi:10.1016/j.isprsjprs.2015.01.017

Cited by 50 publications

(49 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Therefore, there is an EVI uncertainty that stems from the influence of other surface elements apart from vegetation, such as bare soil or outcrops within the pixel, which is our case. In fact, previous studies confirm the discrepancy between MODIS-and EC-derived GPP estimates, especially on sparse vegetation areas with low productivity (Gilabert et al, 2015). However, EVI data have allowed us to complement our findings based on CO 2 fluxes, especially when EC data losses occurred.…”

Section: Amoladerassupporting

confidence: 70%

Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

et al. 2018

View full text Add to dashboard Cite

Abstract. Currently, drylands occupy more than one-third of the global terrestrial surface and are recognized as areas vulnerable to land degradation. The concept of land degradation stems from the loss of an ecosystem's biological productivity due to long-term loss of natural vegetation or depletion of soil nutrients. Drylands' key role in the global carbon (C) balance has been recently demonstrated, but the effects of land degradation on C sequestration by these ecosystems still need to be investigated. In the present study, we compared net C and water vapor fluxes, together with satellite, meteorological and vadose zone (CO 2 , water content and temperature) measurements, between two nearby (∼ 23 km) experimental sites representing "natural" (i.e., site of reference) and "degraded" grazed semiarid grasslands. We utilized data acquired over 6 years from two eddy covariance stations located in southeastern Spain with highly variable precipitation magnitude and distribution. Results show a striking difference in the annual C balances with an average net CO 2 exchange of 196 ± 40 (C release) and −23 ± 2 g C m −2 yr −1 (C fixation) for the degraded and natural sites, respectively. At the seasonal scale, differing patterns in net CO 2 fluxes were detected over both growing and dry seasons. As expected, during the growing seasons, greater net C uptake over longer periods was observed at the natural site. However, a much greater net C release, probably derived from subterranean ventilation, was measured at the degraded site during drought periods. After subtracting the nonbiological CO 2 flux from net CO 2 exchange, flux partitioning results point out that, during the 6 years of study, gross primary production, ecosystem respiration and water use efficiency were, on average, 9, 2 and 10 times higher, respectively, at the natural site versus the degraded site. We also tested differences in all monitored meteorological and soil variables and CO 2 at 1.50 m belowground was the variable showing the greatest intersite difference, with ∼ 1000 ppm higher at the degraded site. Thus, we believe that subterranean ventilation of this vadose zone CO 2 , previously observed at both sites, partly drives the differences in C dynamics between them, especially during the dry season. It may be due to enhanced subsoil-atmosphere interconnectivity at the degraded site.

show abstract

Section: Amoladerassupporting

confidence: 70%

Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The daily conversion efficiency is generally taken as the product of a biome-specific maximum value (g·MJ −1 ) and several dimensionless factors accounting for the efficiency reduction due to different types of stress, such as the thermal and the water stress. Our study area is characterized by different Mediterranean ecosystems where the water stress introduces most of the inter-annual variability in ε i [4,13]. On a daily scale, the different types of stress must be accounted for at quasi-real time, which is rather difficult and frequently requires actual meteorological data.…”

Section: A Theoretically Sound Approachmentioning

confidence: 99%

“…GPP is calculated from in situ net primary production data acquired in eddy covariance (EC) towers after correction for respiration losses [1,2]. Ecosystem models [3] validated against EC data and combined with meteorological and remotely sensed data [4,5] allow for the estimation of GPP across space and time and, hence, for the quantification of carbon fluxes at regional to global scales [2].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Annual Gross Primary Production from Vegetation Indices: A Theoretically Sound Approach

2017

View full text Add to dashboard Cite

Abstract:A linear relationship between the annual gross primary production (GPP) and a PAR-weighted vegetation index is theoretically derived from the Monteith equation.A semi-empirical model is then proposed to estimate the annual GPP from commonly available vegetation indices images and a representative PAR, which does not require actual meteorological data. A cross validation procedure is used to calibrate and validate the model predictions against reference data. As the calibration/validation process depends on the reference GPP product, the higher the quality of the reference GPP, the better the performance of the semi-empirical model. The annual GPP has been estimated at 1-km scale from MODIS NDVI and EVI images for eight years. Two reference data sets have been used: an optimized GPP product for the study area previously obtained and the MOD17A3 product. Different statistics show a good agreement between the estimates and the reference GPP data, with correlation coefficient around 0.9 and relative RMSE around 20%. The annual GPP is overestimated in semiarid areas and slightly underestimated in dense forest areas. With the above limitations, the model provides an excellent compromise between simplicity and accuracy for the calculation of long time series of annual GPP.

show abstract

“…Este último incorpora la conversión de unidades de energía a masa, por lo que también es conocido como eficiencia de conversión. La LUE, a su vez, se suele calcular a partir de un valor máximo (que depende del tipo de ecosistema) y el producto de una serie de factores adimensionales, con rango de variación de 0 a 1, que modulan la reducción de la eficiencia máxima por diversos tipos de estrés, como el térmico (por baja temperatura) y el hídrico, que es el más importante en zonas mediterráneas (Garbulsky et al, 2010;Gilabert et al, 2015).…”

Section: Introductionunclassified

Variabilidad de la eficiencia en el uso del carbono a partir de datos MODIS

et al. 2017

Self Cite

View full text Add to dashboard Cite

Resumen: La eficiencia en el uso de carbono (CUE) cuantifica el incremento de la biomasa de las plantas a partir del carbono que fijan a través de su actividad fotosintética. En este trabajo se analiza la variación de la CUE anual (estimada a partir del cociente entre los productos de producción primaria neta, NPP, y producción primaria bruta, GPP, anuales de MODIS) en función del tipo de vegetación y de las variables meteorológicas temperatura del aire y precipitación, a lo largo de ocho años en la España peninsular. Los valores más bajos de CUE se encuentran en zonas de vegetación densa con niveles de precipitación de moderada a elevada (superior a 1000 mm/año), mientras que los valores más altos se localizan en zonas más áridas (con precipitación por debajo de 800 mm/año). La influencia de la temperatura es menos marcada. Cuando se analizan las variaciones interanuales de la CUE se observa que, para la mayor parte de los ecosistemas, un incremento de la precipitación produce un incremento de su CUE, mientras que un incremento de la temperatura la disminuye. En este caso, además, la influencia de la temperatura es más significativa desde un punto de vista estadístico. Es decir, para un ecosistema en particular, la CUE disminuye cuando se intensifican las condiciones de aridez.Palabras clave: eficiencia en el uso del carbono (CUE), GPP, NPP, MODIS. Carbon use efficiency variability from MODIS dataAbstract: Carbon use efficiency (CUE) describes how efficiently plants incorporate the carbon fixed during photosynthesis into biomass gain and can be calculated as the ratio between net primary production (NPP) and gross primary production (GPP). In this work, annual CUE has been obtained from annual GPP and NPP MODIS products for the peninsular Spain study area throughout eight years. CUE is spatially and temporally analyzed in terms of the vegetation type and annual precipitation and annual average air temperature. Results show that dense vegetation areas with moderate to high levels of precipitation present lower CUE values, whereas more arid areas present the highest CUE values. However, the temperature effect on the spatial variation of CUE is not well characterized. On the other hand, inter-annual variations of CUE of different ecosystems are discussed in terms of inter-annual variations of temperature and precipitation. It is shown that CUE exhibited a positive correlation with precipitation and a negative correlation with temperature in most ecosystems. Thus, CUE decreases when the ecosystem conditions change towards aridity.

show abstract

Daily GPP estimates in Mediterranean ecosystems by combining remote sensing and meteorological data

Cited by 50 publications

References 55 publications

Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

Annual Gross Primary Production from Vegetation Indices: A Theoretically Sound Approach

Variabilidad de la eficiencia en el uso del carbono a partir de datos MODIS

Contact Info

Product

Resources

About