###### Abstract  
Climate change and variability, soil types and soil characteristics, animal and microbial communities, and photosynthetic plants are the major components of the ecosystem that affect carbon sequestration potential of any location. This study used NASA's Soil Moisture Active Passive (SMAP) Level 4 carbon products, gross primary productivity (GPP), and net ecosystem exchange (NEE) to quantify their spatial and temporal variabilities for selected terrestrial ecosystems across Texas during the 2015-2018 study period. These SMAP carbon products are available at 9 km spatial resolution on a daily basis. The ten selected SMAP grids are located in seven climate zones and dominated by five major land uses (developed, crop, forest, pasture, and shrub). Results showed CO\({}_{2}\) emissions and uptake were affected by land-use and climatic conditions across Texas. It was also observed that climatic conditions had more impact on CO\({}_{2}\) emissions and uptake than land-use in this state. On average, South Central Plains and East Central Texas Plains ecoregions of East Texas and Western Gulf Coastal Plain ecoregion of Upper Coast climate zones showed higher GPP flux and potential carbon emissions and uptake than other climate zones across the state, whereas shrubland on the Trans Pecos climate zone showed lower GPP flux and carbon emissions/uptake. Comparison of GPP and NEE distribution maps between 2015 and 2018 confirmed substantial changes in carbon emissions and uptake across Texas. These results suggest that SMAP carbon products can be used to study the terrestrial carbon cycle at regional to global scales. Overall, this study helps to understand the impacts of climate, land-use, and ecosystem dynamics on the terrestrial carbon cycle. to support carbon sequestration [13]. Ecosystem management also impacts carbon sequestration potentials. For example, deforestation and change in land-use cause loss of biomass and a significant amount of carbon dioxide to be released to the atmosphere [14]. Forests are known for their large atmospheric carbon sequestration potentials [15]. For example, 40% of the global terrestrial biomass is stored in tropical forests [16]. There are more long-term studies of CO\({}_{2}\) dynamics in forests than in grasslands or any other ecosystem. However, carbon sequestration potential of grasslands and pastures is still debatable as some researchers demonstrate that these land uses are carbon neutral, while other researchers provide evidence that grasslands can be significant sources or sinks for atmospheric CO\({}_{2}\)[17; 18]. However, CO\({}_{2}\) exchange between the land surface and atmosphere suggests that land surface could be managed to increase uptake and storage of CO\({}_{2}\), and thus become carbon sinks. Moreover, the loss of CO\({}_{2}\) to the atmosphere by aerobic respiration is a non-linear function of temperature for a wide range of soil moisture content [19]. Several researchers have extensively studied the relationship between land-use change and spatiotemporal variation of carbon fluxes [20; 21; 22; 23]. Some researchers found the concentration of atmospheric CO\({}_{2}\) increasing due to many anthropogenic activities, including land-use changes and burning of fossil fuels [24; 25; 26; 27; 28]. It is important to understand the effects of land-use change on carbon sequestration [5]. [PERSON] et al. (2016) [29] conducted a literature review on the land-use change impact on the carbon cycle. The review covered research conducted in 29 countries at 160 different sites. They concluded land-use change has a significant impact on carbon stocks. However, they also deduced land-use change did not consistently result in either increasing or decreasing carbon stocks. For example, converting farmland to grassland or forestland to grassland increased the carbon stocks, whereas a conversion from grassland to farmland or forest to farmland decreased the carbon stocks.