Future impact of climate extremes in the Mediterranean: Soil erosion projections when fire and extreme rainfall meet

Abstract

Climate change projections over the Mediterranean basin point toward an increase in frequency and intensity of extreme events that will directly impact ecosystems resilience. In this study, we evaluated future trends of soil loss in forestland in Catalonia (NE Spain) due to fires and vegetation dynamics, considering the potential future impacts of co-occurring extreme fire and rainfall events, and assessing how fire suppression can contribute to soil erosion mitigation. The process-based MEDFIRE model was used to simulate changes in forestland due to climate and fires between 2011 and 2050 under six different future scenarios that resulted from the combination of two climatic scenarios and three fire management policies. Annual projections on landscape changes were used to estimate soil loss using the Universal Soil Loss Equation. Projected annual soil losses for forested land in Catalonia ranged between 15 and 16 tons/ha, with scenarios simulating current levels of fire suppression projecting around −5% soil loss than those assuming more relaxed suppression strategies. On average, fires explained 12-16% of annual soil loss in the region, but in fire-severe years, they explained up to 90% of the total annual soil loss. Projected mean total soil loss in years where extreme rainfall and fire meet was 150% higher than in years where both events were not contemporary. The estimated annual probability that the two extreme impacts will co-occur in the future ranged between 0.09 and 0.11 between scenarios. Our results highlight the importance of landscape and fire management in minimizing soil loss and its potential impacts for ecosystems.

Soil Organic Matter Research and Climate Change: Merely Re-storing Carbon Versus Restoring Soil Functions

“…These known facts about organic matter losses in soils take on significant urgency in the context of the ongoing climate change. One of the consistent predictions climate modelers have made over the last decade is that climate change will result in less frequent but more intense rainfall events in many parts of the world (e.g., Trenberth et al, 2003;Sun et al, 2007;Min et al, 2011;Ipcc, 2013; Intergovernmental Panel on Climate Change, 2014; Kendon et al, 2014;Berghuijs et al, 2017;Tang et al, 2019;Hess et al, 2020;Morán-Ordóñez et al, 2020;O'Donnell and Thorne, 2020). In North America, meteorological records indicate that heavy precipitation events have already increased in a large number of areas (Melillo et al, 2014).…”

“…Unless one builds massive numbers of artificial reservoirs, the water deficits will be impossible to compensate via irrigation since available groundwater or surface water resources are already severely overdrawn, causing a whole suite of environmental problems. In addition, more intense rainfall events generally mean quicker ponding at the soil surface and increased runoff, which in turn cause more severe soil erosion, an issue that has become critical in many countries (e.g., Nearing et al, 2004;Morán-Ordóñez et al, 2020;Wang et al, 2020). Beside via soil erosion, higher-intensity rainfalls may also have other effects on soil carbon storage, when the latter is increased through the incorporation of pyrolyzed organic material (e.g., agrichar or biochar).…”

Modelling the Event-Based Hydrological Response of Mediterranean Forests to Prescribed Fire and Soil Mulching with Fern Using the Curve Number, Horton and USLE-Family (Universal Soil Loss Equation) Models

“…The hydrological impacts of fire are particularly important in Mediterranean forests. Here, the frequency, extent, and intensity of wildfires have been associated with an increase in climate warming in the last three decades [5], due to specific weather conditions (e.g., low humidity, high temperature, and strong winds [6]), and hydrological regimes (extreme and flash storm events with heavy and erosive rainfalls [7,8]).…”

Ecosystem services provision by Mediterranean forests will be compromised above 2℃ warming

“…), we observed substantial variation in responses when additional drivers of change were included. For instance, studies explicitly including a CO 2 fertilization effect projected lower impacts of climate change on the services linked to forest growth (Dury et al, 2011; Gaucherel et al, 2008; Keenan et al, 2011), and forest management can also have a larger impact on ecosystem service provision than climate (Morán‐Ordóñez et al, 2020; Palma et al, 2015). Similarly, studies projecting burnt areas rarely account for the potential of mitigating impacts through fire or landscape management (but see for example Duane et al, 2019).…”