## 4 Discussion  
Contrary to the hypothesis tested here, our results showed a negative (r = \(-0.22\), Figure 5) rather a than positive relationship between cattle density and the number of fires in the Pantanal over a 19-year time series (Figure 5). This directly contradicts the notion disseminated by Brazil's current government and the powerful agribusiness sector that rearing of bovine livestock serves to control ecosystem flammability by suppressing grass and shrub biomass, thereby reducing fire intensity and continuity. Were this true, we would expect fewer fire foci in areas occupied by larger numbers of cattle. The results obtained here show that wildfires in this tropical wetland ecosystem are instead related to weather events, particularly droughts. SPI variation across the Brazilian Pantanal is associated with a higher occurrence of fire outbreaks. During the dry years 2002, 2010, and 2019, when the vegetation was desiccated and fire foci were more frequent and widespread, the correlation between SPI variables and fires was markedly negative (r = \(-0.78\)). The same was observed for rainfall correlates of fire foci, which showed an inverse relationship across the entire time series. Those three exceptionally dry years (2002, 2010, and 2019) saw much lower annual rainfall, yielding a strong negative correlation between overall precipitation and fire foci (r = \(-0.795\)), while both of these variables showed no correlation with numbers of cattle. This, again, supports the alternative hypothesis that fire incidence and spread are influenced by climatic factors and are most likely unrelated to herbivy pressure exerted by domesticated livestock. Climate change in the last decade has directly affected the hydrology of the Pantanal biome by reducing precipitation and increasing temperatures [39]. Low rainfall and a temporal shift of the wet season have been observed in the southern Amazon and the Pantanal [40]. Climate change models developed by the Intergovernmental Panel on Climate Change (IPCC) predict an increase of 5 \({}^{\circ}\)C to 7 \({}^{\circ}\)C in mean air temperature by 2100 [41], which, combined with a drier environment, suggests a future scenario in which vegetation flammability could vastly increase across the Pantanal. The argument for deploying \"cattle to fight fires\", as professed in some policy arenas, is not valid, since the main determinants of reduced fire incidence are declining overall precipitation and prolonged droughts. For example, we highlight the severe recent droughts of 2019 and 2020, which severely aggravated the spread of fires in the Pantanal and the Upper Paraguay basin [42]. Therefore, regional scale climate change tends to tip the balance towards drier and hotter episodes, which will likely aggravate the severity of seasonal droughts in years to come [8; 11], paving the way for more frequent and more intensive uncontrolled fires with much greater impacts on flora and fauna across the Pantanal ecosystem. It is important to highlight that dry-season fires (May to September) are almost entirely anthropogenic, since fires are deliberately lit as part of a widely used low-cost method [43; 44] to both clear vegetation [42] and renew pastures [8; 44; 45]. However, uncontrolled wildfires induced by agricultural practices are related to inadequate fire use, which results in severe detrimental consequences for ecosystem integrity [22; 46]. In this study, we noted that GPP explained 98% of the variation in woody biomass (Figure 6) and that GPP was negatively correlated with fire incidence (r = \(-0.235\)). These findings suggest that fires did not necessarily match the proxied availability of fuel loads, even where plant biomass was elevated (Figure 7), which is again inconsistent with the notion of \"cattle firefighting\". Rainfall and SPI also failed to explain GPP increments along the time series.