Assessing the relationship between microwave vegetation optical depth and gross primary production

Published by Ecoss on

At the global scale, the uptake of atmospheric carbon dioxide by terrestrial ecosystems through photosynthesis is commonly estimated through vegetation indices or biophysical properties derived from optical remote sensing data. Microwave observations of vegetated areas are sensitive to different components of the vegetation layer than observations in the optical domain and may therefore provide complementary information on the vegetation state, which may be used in the estimation of Gross Primary Production (GPP). However, the relation between GPP and Vegetation Optical Depth (VOD), a biophysical quantity derived from microwave observations, is not yet known. This study aims to explore the relationship between VOD and GPP. VOD data were taken from different frequencies (L-, C-, and X-band) and from both active and passive microwave sensors, including the Advanced Scatterometer (ASCAT), the Soil Moisture Ocean Salinity (SMOS) mission, the Advanced Microwave Scanning Radiometer for Earth Observation System (AMSR-E) and a merged VOD data set from various passive microwave sensors. VOD data were compared against FLUXCOM GPP and Solar-Induced chlorophyll Fluorescence (SIF) from the Global Ozone Monitoring Experiment-2 (GOME-2). FLUXCOM GPP estimates are based on the upscaling of flux tower GPP observations using optical satellite data, while SIF observations present a measure of photosynthetic activity and are often used as a proxy for GPP. For relating VOD to GPP, three variables were analyzed: original VOD time series, temporal changes in VOD (ΔVOD), and positive changes in VOD (ΔVOD≥0). Results show widespread positive correlations between VOD and GPP with some negative correlations mainly occurring in dry and wet regions for active and passive VOD, respectively. Correlations between VOD and GPP were similar or higher than between VOD and SIF. When comparing the three variables for relating VOD to GPP, correlations with GPP were higher for the original VOD time series than for ΔVOD or ΔVOD≥0 in case of sparsely to moderately vegetated areas and evergreen forests, while the opposite was true for deciduous forests. Results suggest that original VOD time series should be used jointly with changes in VOD for the estimation of GPP across biomes, which may further benefit from combining active and passive VOD data.

Categories:

Related Posts

A CIRCUIT SHOWS HOW CLIMATE WARMING MAY ALTER DIFFERENT ECOLOGICAL LEGACIES IN THE ARCTIC BOREAL FOREST, WHICH THEN FEEDBACK INTO CLIMATE WARMING AND CHANGES TO LANDSCAPE PROCESSES.

NAU-led research team receives $9.6M to study how Alaska’s forests change, adapt to warmer future

Ecological memory stored in a landscape can help an ecosystem recover from disturbances like fire and outbreaks of disease. But what happens when climate warming disrupts that process? How long before ecological memories stored in Read more…

A SCATTERPLOT DEPICTS HOW MUCH CARBON OR OXYGEN ISOTOPE DIFFERENT SOIL BACTERIA TOOK INTO THEIR DNA (A PROXY FOR GROWTH) DURING A 7-DAY EXPERIMENT. SMALL POINTS REPRESENT THE GROWTH OF INDIVIDUAL BACTERIAL STRAINS LINKED BY LINES TO THE AVERAGE GROWTH OF THEIR CLOSEST IDENTIFIED GENUS. COLORS WERE ASSIGNED BY A CLUSTERING ALGORITHM TO GROUP GENERA INTO FAST-GROWING OR SLOW-GROWING LIFESTYLES.

Lifestyles of the fast and slow (bacteria): In the wild, most live in the slow lane

A study led by Northern Arizona University offers new evidence that a common framework to sort bacteria into two lifestyles doesn’t easily apply to bacteria living in wild soil. The findings, published in The ISME Journal, show Read more…

A trio of illustrated panels depicts the soil microbial communities in three treatments of a long-term warming experiment north of Flagstaff, Arizona. The panels are labeled in gray text, left to right: control, short-term warming, long-term warming. The control treatment, far left, depicts bacteria, protists, and other microorganisms identified by sequencing the soil’s metagenome in yellow, orange, green, and blue, along with chains of available nutrients. Soil depicted in the center panel, which has undergone short-term warming, shows an increased abundance and diversity of microbes, some of which are growing, incorporating nutrients, and respiring carbon dioxide. The soil that has undergone long-term warming, imagined in the panel on the right, shows fewer microbial species and competitive relationships that are developing for control of the scarcer nutrients.

Does a warmer future favor microbial friend or foe? Ecoss researchers win $3.4M to study interactions in changing soil

In 2002, the Odyssey probe discovered evidence of past ice on Mars. The U.S. Congress authorized the Iraq War resolution. The Anaheim Angels won the World Series. And in a meadow 15 miles north of Read more…