## 3 Results and Discussion
### Comparison of CO\({}_{2}\) Fluxes and ET during Dormant Seasons among Pastures
In addition, P13, P14, P15, and P16 are rotationally grazed year-round, while P18 is grazed during May through early July only, which results in larger amounts of standing biomass present during winter compared to other pastures. Frequent burning increases the fraction of C\({}_{4}\) grasses and decreases plant species richness and diversity of tallgrass prairie, while less-frequent burning and grazing increase C\({}_{3}\) grasses and forbs [53]. The warm-season C\({}_{4}\) grasses of prairie ecosystems are dormant during the winter, with only decadent and senesced materials present aboveground. However, cool-season C\({}_{3}\) species are metabolically active at low temperatures during winter [54]. Consequently, smaller rates and budgets of CO\({}_{2}\) fluxes and ET can be expected during  
Figure 8: Daily patterns of evapotranspiration (ET) (**a**), net ecosystem CO\({}_{2}\) exchange (NEE) (**b**), and gross primary production (GPP) (**c**) in multiple prairie pastures during the 2020–2021 non-growing season (November–March), except during the 2019–2020 growing season for P20. the dormant season for pastures that are not extensively grazed (P18) and receive annual burning. Furthermore, cumulative CO\({}_{2}\) fluxes and ET in P18 showed smaller interannual variations than in other pastures for the November-February period (Table 1), most likely due to the reduced presence of C\({}_{3}\) species. Although we hypothesized that CO\({}_{2}\) fluxes and ET would be similar during dormant seasons across differently managed prairie pastures and years, we observed considerable discrepancies in rates and budgets of CO\({}_{2}\) fluxes and ET among pastures and years. The NEE is a complicated process since it includes ecosystem respiration (both autotrophic and heterotrophic). Several sub-surface and surface processes such as decomposition of soil organic matter, soil microbial abundance and community, and meteorological conditions (e.g., temperature, moisture, radiation, wind speed) can influence NEE during dormant seasons [22]. Consequently, ET and GPP are more directly influenced by rainfall and the presence of green vegetation, respectively, than NEE. However, we noticed the MODIS-derived EVI and NDVI values were similar for some periods when flux magnitudes were different among pastures and years, indicating MODIS-derived vegetation indices were not fully capable to track the presence of some cool-season C\({}_{3}\) species under residues and litter layers of tallgrass prairie. The responses of native prairie systems to different management and environmental factors are varied and complex due to differences in plant community composition (i.e., different proportions of C\({}_{3}\) and C\({}_{4}\) grasses and C\({}_{3}\) forbs) and positions (i.e., slope position, exposure) within landscapes [44; 55; 56]. There can be interactive impacts of different management and environmental factors on the proportion of C\({}_{3}\) species, microbial activities, and soil fluxes. Documenting changes in species' composition (e.g., the abundance of C\({}_{3}\) species) during winter (dormant season) is necessary to explain some discrepancies in dormant season fluxes. A multi-level validation approach of using ground-truth observations of species' composition, EC measurements, PhenoCams (digital cameras), and finer-resolution satellite data is required to further validate the vegetation phenology derived from the MODIS during the dormant season. Such datasets will also allow an investigation of the multifaceted associations (i.e., main and interactive impacts) between vegetation phenology, different management practices, and climatic drivers. Further, several years of EC measurements are needed over the complete years from multiple prairie pastures to more accurately quantify interannual variability in CO\({}_{2}\) fluxes and ET in response to controlling factors during both growing and non-growing seasons of this important ecosystem.