Direct and indirect impacts of wildfire on faunal communities of Mediterranean temporary ponds

Abstract

The Mediterranean region has historically been affected by wildfires. However, studies addressing wildfire impacts have traditionally focused first on terrestrial systems and second on lotic systems. This bias has left a gap in knowledge related to wildfire effects on some of the emblematic habitats of the Mediterranean region such as temporary ponds. We hypothesise that temporary ponds will experience indirect consequences of wildfires like those of other aquatic systems (e.g. nutrient increases or trophic alterations). However, the fact that temporary ponds are dry during the summer, when most wildfires occur, could add a new path of disturbance such as an impact on organisms aestivating in the pond sediment due to their direct burning. Based on these hypotheses, the present study analyses wildfire impacts on faunal communities adapted to temporality, focusing on species traits related to expected indirect and direct impacts (i.e. dispersal ability, life history or feeding habits). We took advantage of a wildfire (summer 2012) that partially affected a Mediterranean temporary pond network, comparing the environmental and the faunal community responses from before and after the wildfire, and between the burned and unburned ponds during the subsequent hydroperiod. As hypothesised, our results indicated different wildfire effects. First, changes in abundances of some trophic groups from before and after the wildfire but also strong fluctuations at the beginning of the hydroperiod between burned and unburned ponds. Second, a decrease in abundance of organisms that remain in the pond sediment during drought in burned ponds, being probably affected directly by the wildfire. Only one hydroperiod appears to be sufficient for burned ponds to recover their similarity to unburned ponds, which highlights the high resilience of these communities. Despite their resilience, these communities could become compromised in the future since global change scenarios predict increase wildfire frequency and intensity in the Mediterranean region.

Addressing trait selection patterns in temporary ponds in response to wildfire disturbance and seasonal succession

“…Larger body sizes seem to be favoured after a wildfire (Bargmann et al, 2016), which is likely due to a recolonization dynamic, in which relatively large organisms are capable of reaching disturbed sites and tolerating new conditions. Additionally, in the studied systems, these organisms likely benefit from a lack of competition among the directly burned organisms (Cunillera-Montcusí et al, 2019).…”

“…For more detailed information on the wildfire and how the ponds were affected, see Cunillera-Montcusí et al (2019). and fulvic acid percentage (%AC.FUL.).…”

“…The macroinvertebrates were preserved in situ in 4% formaldehyde for identification to the species level whenever possible. See Àvila, López-Flores, Boix, Gascón, and Quintana (2016), Ballón et al (2016) and Cunillera-Montcusí et al (2019) for more detailed information on the sampling procedure, sample processing and water analyses.…”

“…Macrophyte loss may influence refuge and resource availability (Rodríguez-Tricot & Arim, 2020), favouring traits associated with antipredator strategies or determined feeding groups. Finally, in a community affected by a wildfire, organisms with limited dispersal abilities may be directly burnt due to their impossibility to escape from it (Chittapun, 2011;Cunillera-Montcusí et al, 2019). Therefore, wildfires may disrupt community assembly mechanisms leading to changes in trait selection.…”

Metacommunity resilience against simulated gradients of wildfire: disturbance intensity and species dispersal ability determine landscape recover capacity

“…The empirical evaluation of these relationships is limited to a few ecosystems or taxa (Sorensen and Shade 2020), making theoretical evaluations rooted in real systems particularly valuable to advance our knowledge of disturbance and landscape interactions (Miller et al 2019). Here, we analyse these general relationships between disturbance and resilience with a focus on a model study system – a water body network located on the NE Iberian Peninsula – for which key information about pondscape arrangement, species biology, community structure and response to disturbance is available (Cunillera‐Montcusí et al 2019, 2020a). To address this aim, we developed a metacommunity lottery model in which the pondscape was captured in a network inferred from species dispersal ability and regional water body locations.…”