Search

Increasing wildfire frequency in the Mediterranean Basin could affect future plant-soil–water-dynamics. The capacity of soils to retain water is a key parameter affecting plant post-fire regeneration. Yet, few research has looked at how different soil properties related to water retention is affected by increasing wildfire frequency. This study aimed at understanding the relationship between wildfire frequency, soil–water-related properties and the dynamics of surface water in soils. To this, after a 2012-summer wildfire in Portugal, three sets of three replicate maritime pine stands with contrasted wildfire frequency were selected (0 vs. 1 vs. 4 fires since 1975). At each of the nine study sites, three re-sprouter shrubs and neighbouring bare soil were chosen (54 microsites). There, soil cover, soil–water retention curves and surface (0–5 cm) soil–water-related properties (texture, bulk density, organic matter content, soil moisture, soil surface water repellency) were monitored for one year. Furthermore, records of post-fire soil moisture dynamics were analysed continuously using 72 probes installed at 2.5 and 7.5 cm depth. The hillslopes affected by 1 fire showed higher plant recovery than the 4 fires hillslopes. During the dry season, the threshold for water stress was reached 17 days sooner in the 4 fires hillslopes, and also 10 days sooner on bare microsites. Periods of plant water stress were longer and bare soil patches size bigger. The increase in wildfire frequency promoted high soil organic matter contents but less available water content, stressing the importance of soil organic matter quality characterization in water-related properties.

Recurrent fires can impede the spontaneous recruitment capacity of pine forests. Empirical studies have suggested that this can lead to a prolonged replacement of pine forest by shrubland, especially if shrub species are pyrophytic. Model-based studies, however, have suggested that post-fire succession of pine forest under current climatic conditions will eventually tend towards the dominance of oaks under high fire severity and recurrence. These previous modelling studies did not address the role of the various post-fire regeneration traits of the understory shrub species. Considering the dichotomy of obligate seeder vs. resprouter species, either obligate or facultative resprouter, we hypothesized that when the shrubs present are post-fire seeders, the oaks steadily occupy the forest, whereas resprouter shrub species might compete with oaks and delay or arrest post-fire succession. To test this hypothesis, we developed a dynamic, cellular automaton model for simulating post-fire successional transitions in pine forests, including shrubs, pines and oaks, and stochastic fires of regular frequency. Our results showed a strong tendency towards oak dominance as final model state and a very reduced role of fire recurrence in this final state, with low yearly acorn input delaying oak dominance. Most relevantly, and in line with our hypothesis, the trend towards oak dominance depended markedly on the two types of shrub species, being delayed by resprouter species, which extended the shrub-dominated succession stage for several centuries. Our simulation results supported the view that the type of understorey species should be a key consideration in post-fire restoration strategies aiming to enhance fire resilience.

Climate change is a world-wide threat to biodiversity and ecosystem structure, functioning and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate change impacts across the soil-plant-atmosphere continuum. An increasing number of climate change studies are creating new opportunities for meaningful and high-quality generalizations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re-use, synthesis and upscaling. Many of these challenges relate to a lack of an established 'best practice' for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change. To overcome these challenges, we collected best-practice methods emerging from major ecological research networks and experiments, as synthesized by 115 experts from across a wide range of scientific disciplines. Our handbook contains guidance on the selection of response variables for different purposes, protocols for standardized measurements of 66 such response variables and advice on data management. Specifically, we recommend a minimum subset of variables that should be collected in all climate change studies to allow data re-use and synthesis, and give guidance on additional variables critical for different types of synthesis and upscaling. The goal of this community effort is to facilitate awareness of the importance and broader application of standardized methods to promote data re-use, availability, compatibility and transparency. We envision improved research practices that will increase returns on investments in individual research projects, facilitate second-order research outputs and create opportunities for collaboration across scientif

One of the most challenging issues in Mediterranean ecosystems to date has been to understand the emergence of discontinuous changes or catastrophic shifts. In the era of the 2030 Sustainable Development Goals, which encompass ideas around Land Degradation Neutrality, advancing this understanding has become even more critical and urgent. The aim of this paper is to synthesize insights into the drivers, processes and management of catastrophic shifts to highlight ways forward for the management of Mediterranean ecosystems. We use a multidisciplinary approach that extends beyond the typical single site, single scale, single approach studies in the current literature. We link applied and theoretical ecology at multiple scales with analyses and modeling of human–environment–climate relations and stakeholder engagement in six field sites in Mediterranean ecosystems to address three key questions: i) How do major degradation drivers affect ecosystem functioning and services in Mediterranean ecosystems? ii) What processes happen in the soil and vegetation during a catastrophic shift? iii) How can management of vulnerable ecosystems be optimized using these findings? Drawing together the findings from the use of different approaches allows us to address the whole pipeline of changes from drivers through to action. We highlight ways to assess ecosystem vulnerability that can help to prevent ecosystem shifts to undesirable states; identify cost-effective management measures that align with the vision and plans of land users; and evaluate the timing of these measures to enable optimization of their application before thresholds are reached. Such a multidisciplinary approach enables improved identification of early warning signals for discontinuous changes informing more timely and cost-effective management, allowing anticipation of, adaptation to, or even prevention of, undesirable catastrophic ecosystem shifts.

One of the most challenging issues in Mediterranean ecosystems to date has been to understand the emergence of discontinuous changes or catastrophic shifts. In the era of the 2030 Sustainable Development Goals, which encompass ideas around Land Degradation Neutrality, advancing this understanding has become even more critical and urgent. The aim of this paper is to synthesize insights into the drivers, processes and management of catastrophic shifts to highlight ways forward for the management of Mediterranean ecosystems. We use a multidisciplinary approach that extends beyond the typical single site, single scale, single approach studies in the current literature. We link applied and theoretical ecology at multiple scales with analyses and modeling of human–environment–climate relations and stakeholder engagement in six field sites in Mediterranean ecosystems to address three key questions:i) How do major degradation drivers affect ecosystem functioning and services in Mediterranean ecosystems?ii) What processes happen in the soil and vegetation during a catastrophic shift?iii) How can management of vulnerable ecosystems be optimized using these findings?Drawing together the findings from the use of different approaches allows us to address the whole pipeline of changes from drivers through to action. We highlight ways to assess ecosystem vulnerability that can help to prevent ecosystem shifts to undesirable states; identify cost-effective management measures that align with the vision and plans of land users; and evaluate the timing of these measures to enable optimization of their application before thresholds are reached. Such a multidisciplinary approach enables improved identification of early warning signals for discontinuous changes informing more timely and cost-effective management, allowing anticipation of, adaptation to, or even prevention of, undesirable catastrophic ecosystem shifts.

In Mediterranean forests and rangelands, the supply of important ecosystem services can decrease or cease as a consequence of disturbances and climatic oscillations. Land managers can sometimes prevent or mitigate the negative effects of disturbances through appropriate land management choices. In this study, we assess the contribution of land management practices (LMPs) to the resilience of eight Mediterranean forests and rangelands to multiple disturbances. The study uses a transdisciplinary approach, involving scientists, land managers, and local administrators. Data about disturbances, ecosystem services, the role of LMPs, and the resistance of LMPs to disturbances are combined using a semiquantitative index and analysed to evaluate how the LMPs implemented are suited to the disturbances affecting each study site. Our results indicate that the practices analysed are particularly effective in improving resilience of ecosystems against wildfires and torrential rainfalls. However, droughts are more difficult to address, and the examined practices were heavily affected by their occurrence. Tree planting appears to be highly affected by disturbances. Practices that selectively reduce the amount of vegetation appear to be beneficial in fostering recovery of ecosystems. Our assessment also suggests that it is particularly difficult to increase resilience to droughts and fires simultaneously. Practices that aimed to mitigate the impact of land use did not always prove valuable in terms of resilience. Finally, study sites that included efforts to address disturbances in their management objectives also displayed practices making the biggest contribution to resilience.