Wildfire effects on macroinvertebrate communities in Mediterranean streams / Efectes dels incendis forestals sobre las comunitats de macroinvertebrats en rius Mediterranis

摘要

[eng] Wildfire effects on macroinvertebrate communities have not been intensively studied in other areas than the Western US, and the results in fire prone areas like NE Mediterranean and SE Australia are scarce. In this study, Mediterranean streams (both fire affected and control) presented the highest dominance of r-strategy taxa, which are characterized by their high resilience. However, three years after fire, the indirect effects of the riparian canopy removal was still significant in these streams. Located in the same burned catchment, severely canopy affected area of the Vall d'Horta stream showed high aquatic vegetation cover compared to intact canopy cover, which showed, in turn, a high leaf litter cover percentage. Although differences in organic cover were significant in the macroinvertebrate community structure and turnover, hydrology was also a very important factor that marked the succession of communities along the year in both reaches. In the Mediterranean region, our studies conclude that midterm effects of fire on macroinvertebrate communities (up to 5 years) showed the importance of yearly precipitation in their response, and important differences in macroinvertebrate community dynamics were found depending if the year was wet or dry. We conclude that macroinvertebrate communities that live in Mediterranean climate streams showed in general high resilience to fire, because they usually have to cope with other severe disturbances like flooding and drought. The results obtained in this study indicate that other disturbances like droughts and floods can modulate the severity of the responses of the macroinvertebrate communities. In general, as in other biomes, post-fire precipitations are the most severe indirect effects where a large input of nutrients and dramatic habitat change takes place. In the Mediterranean catchments usually the big flood occurs few weeks after the wildfire, while in the other studied biomes the effects could be delayed by drought (SE Australia) or by the hydrologic characteristics from the stream itself (NW USA). Furthermore, if all these disturbances will come more often and together in the future, the presence of many species may be compromised, especially those that now are not found or found in low numbers in the dry years.