## 4 Discussion
Notably, these evaluations occurred in years of El Nino and La Nina phenomena, showing that the variations found in this work represent the different climatic conditions. However, ecosystem adaptations to climate change can occur naturally and in relation to management, reinforcing the need to increase flux tower measurements over the years. Grazing management was performed at intervals of 750 DD. This association between pasture management and weather conditions makes it difficult to distinguish their isolate impact on the NEE. For instance, if there are high temperatures and greater precipitation in a certain period of the year, the more significant plant growth is compensated by more intense grazing due to the pasture's improved nutritional quality. The opposite occurs  
Figure 6: Relation between year-to-year changes in GPP (dGPP/dt) and Reco (dReco/dt). Solid line represents the linear fit of the data. For reference, the dashed black line represents 1:1 relation. in periods of low pasture growth when grazing is less intense, and for this reason, no relationships between interannual variability in NEE and weather and animal management variables were found in our analysis (Figure S2). This coupling between weather conditions and management could also partly explain the low NEE interannual variability in the main animal production period (warm season, Tables 1 and 2) [53]. Nevertheless, this seems to be a typical characteristic of grasslands [55; 56]. [PERSON] et al. [51] analyzed the carbon balance of permanent grasslands in Belgium and reported not finding any correlation between weather variables anomalies and NEE anomalies. Our study also found no relationship between animal productivity and NEE, although the relationships between pasture height and NEE, GPP, and Reco are linear (Figure S1). The periods of the highest CO\({}_{2}\) uptake occurred when the pasture was the highest (i.e., 28-35 cm; Tables 1 and 2). Other researchers have indicated that these grazing heights increased animal production and the mitigation of the environmental impact of rarching in the subtropical region of Brazil [57]. However, [PERSON] et al. [58] related higher pasture heights with lower photosynthetic rates due to an increased percentage of older leaves and a more significant accumulation of stems and dead material. In this situation, Reco remains high while GPP decreases. In our study, Reco and GPP increased as pasture height increased, although GPP showed greater increases than Reco (Figure S2). This demonstrates that the cattle management was correct, allowing the pasture to grow and preventing its senescence. Therefore, grazing should not be performed at heights above those indicated as it will also reduce the animals' weight gain due to the pasture's lower nutritional quality [57]. A good-quality pasture provides an adequate cattle nutrition and greater weight gain. In this study, the adequate adjustment of the animal load provided a weight gain of 130.6 kg LW ha\({}^{-1}\) in the average of the warm seasons of the 5 years evaluated (Table 1). This result is 87% higher than the average of Rio Grande do Sul State, which is 70 kg LW ha\({}^{-1}\)[2]. The average stocking rate of animals in the experimental area during the warm season was 944.1 kg LW ha\({}^{-1}\), corresponding to 2.1 AU ha\({}^{-1}\) (1 AU, animal unit, is equivalent to 450 kg LW). This stocking rate is more than double the one used in cattle production systems on native pastures in the Pampa biome, which is approximately 1 AU [2]. This indicates that rural producers can improve pasture management in the Pampa biome to increase the animal load and meat production per area without degrading the pasture. Our findings demonstrate that the Pampa Biome's natural pastures are vital in absorbing CO\({}_{2}\) from the atmosphere when well managed. Evidence has also shown that grazing can mitigate CH\({}_{4}\) emissions from ruminants if combined with appropriate pasture management practices [59; 60; 61].