Influence of climate variability, fire and phosphorus limitation on vegetation structure and dynamics of the Amazon–Cerrado border

Abstract

Abstract. Climate, fire and soil nutrient limitation are important elements that affect vegetation dynamics in areas of the forest-savanna transition. In this paper, we use the dynamic vegetation model INLAND to evaluate the influence of interannual climate variability, fire and phosphorus (P) limitation on Amazon-Cerrado transitional vegetation structure and dynamics. We assess how each environmental factor affects net primary production, leaf area index and aboveground biomass (AGB), and compare the AGB simulations to an observed AGB map. We used two climate data sets (monthly average climate for 1961-1990 and interannual climate variability for 1948-2008), two data sets of total soil P content (one based on regional field measurements and one based on global data), and the INLAND fire module. Our results show that the inclusion of interannual climate variability, P limitation and fire occurrence each contribute to simulating vegetation types that more closely match observations. These effects are spatially heterogeneous and synergistic. In terms of magnitude, the effect of fire is strongest and is the main driver of vegetation changes along the transition. Phosphorus limitation, in turn, has a stronger effect on transitional ecosystem dynamics than interannual climate variability does. Overall, INLAND typically simulates more than 80 % of the AGB variability in the transition zone. However, the AGB in many places is clearly not well simulated, indicating that important soil and physiological factors in the Amazon-Cerrado border region, such as lithology, water table depth, carbon allocation strategies and mortality rates, still need to be included in the model.

Fire Affects Asymbiotic Nitrogen Fixation in Southern Amazon Forests

“…Fire disturbance can disrupt biological processes and biogeochemical cycles, notably those concerning N (Pellegrini et al, 2018), which can influence natural succession in dystrophic, nutrient-poor soils (de Oliveira et al, 2017;Nardoto et al, 2014;Taylor et al, 2019). For example, the effect of fire includes transformations of the soil organic and inorganic pools with subsequent loss through volatilization or via export of particulate matter (Certini, 2005;Crutzen & Andreae, 2016;Dionizio et al, 2018;Mataix-Solera et al, 2011;Schlesinger et al, 2016). Fires can lead to significant losses of carbon (C) and N through combustion and volatilization (Pellegrini et al, 2014;Silva et al, 2015), even though mineral elements, such as phosphorus (P), can become readily available following fire-induced mineralization of soil organic matter (Butler et al, 2018).…”

Impacts of Fire on Forest Biomass Dynamics at the Southern Amazon Edge

“…A key conservation challenge within the ZOT, therefore, is to understand the current trajectory of ecosystem change and which factors may helpor hinderefforts to protect remaining ecosystems. While forests in the ZOT are exceptionally dynamic and variable compared to other forests in Amazonia and beyond in the tropics (Phillips et al 1994, and in spite of modelling and experimental work on the drivers of vegetation dynamics in the ZOT (e.g., Hirota et al 2010, Dionizio et al 2018, Silverio et al 2019, there has been little attempt to actually assess on the ground how remaining vegetation here has fared. However, a state-wide network of monitoring plots capable of assessing ecosystem functions and change in relation to environmental impacts is now available in the ZOT of Mato Grosso (Marimon et al 2014, Morandi et al 2016.…”

Climate and soils at the Brazilian semiarid and the forest-Caatinga problem: new insights and implications for conservation

“…Thus, allowed a better separation of vegetation classes (figure 2 and table 2). Therefore, the importance of soil is not limited to the landscape scale unlike what Willis and Whittaker (2002) suggest, but is also an environmental factor that should not be neglected at regional scales (Arruda et al 2017, Langan et al 2017, Dionizio et al 2018, Casalini et al 2019. In the context of this study, Al 3+ saturation, base saturation and K content were the most important soil attributes.…”

“…The geographical distribution of natural vegetation and biodiversity on Earth can be understood at different scales (Willis and Whittaker 2002). On a continental scale, climate explains the vegetation distribution and defines transitions between biomes (Woodward et al 2004, Arruda et al 2017, Langan et al 2017, Dionizio et al 2018, Casalini et al 2019. On a local scale, one can expect for a lower climate explanatory power and a greater importance of soil and topographic factors (Trejo andDirzo 2002, Arruda et al 2015a).…”