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Background <p>Physical dormancy in Mediterranean Cistaceae is commonly interpreted as a fire-related adaptation. Yet in semi-arid catchments, hard-coated seeds are also exposed to sediment-laden runoff, where abrasion, transport and water availability may occur together. This raises a broader ecological question: are dormancy release and recruitment in Mediterranean obligate seeders filtered mainly by fire, or by interacting thermal and hydrological disturbance processes? We addressed this question in <i>Cistus albidus</i> L., a widespread western Mediterranean shrub, by comparing dry heat, simulated wildfire, runoff-driven scarification, manual scarification and one-year natural ageing using seeds from six mother plants. A complementary establishment trial assessed whether germination translated into early seedling survival under contrasting seasonal conditions.</p> Results <p>Fresh seeds germinated well after all dormancy-breaking treatments. Final germination did not differ significantly among replicated fresh-seed treatments, reaching 80.7% after dry heat, 72.6% after simulated wildfire and 73.9% after manual scarification. Runoff scarification, interpreted descriptively because seeds were processed as a single composite batch, produced similarly high germination (78.4%). Simulated wildfire mainly accelerated germination: seeds reached 50% germination faster than after dry heat, but final germination was not higher. One-year-old seeds retained substantial viability but showed low germination after 12-h hydration, indicating that physical dormancy persisted after one year; extended hydration partly increased germination within the aged cohort. Seedling emergence was high in both establishment trials, but survival was strongly seasonal. Summer cohorts showed near-complete post-emergence mortality, whereas autumn cohorts maintained high survival after 60&#xa0;days.</p> Conclusions <p>Regeneration in <i>C. albidus</i> is not adequately explained by strict fire dependence. Heat exposure provides a rapid dormancy-breaking cue, whereas the runoff simulation provides evidence for a plausible hydrological pathway in which seed-coat abrasion and water exposure are coupled. Fire and runoff may therefore act as complementary recruitment filters with different temporal consequences. These findings support an interpretation of <i>C. albidus</i> as a flexible obligate seeder whose recruitment depends on the alignment between dormancy release, hydration and post-emergence conditions. Mediterranean shrubland models should incorporate hydrological scarification, seasonal establishment bottlenecks and the increasing mismatch between fire and rainfall regimes.</p> Graphical Abstract <p></p>

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Fire and runoff as complementary ecological filters shaping dormancy release and recruitment in Cistus albidus L.

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月14日

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  • Daniel Raus de Baviera,
  • Antonio Ruiz-Canales,
  • Enrique Barrajón-Catalán

摘要

Background

Physical dormancy in Mediterranean Cistaceae is commonly interpreted as a fire-related adaptation. Yet in semi-arid catchments, hard-coated seeds are also exposed to sediment-laden runoff, where abrasion, transport and water availability may occur together. This raises a broader ecological question: are dormancy release and recruitment in Mediterranean obligate seeders filtered mainly by fire, or by interacting thermal and hydrological disturbance processes? We addressed this question in Cistus albidus L., a widespread western Mediterranean shrub, by comparing dry heat, simulated wildfire, runoff-driven scarification, manual scarification and one-year natural ageing using seeds from six mother plants. A complementary establishment trial assessed whether germination translated into early seedling survival under contrasting seasonal conditions.

Results

Fresh seeds germinated well after all dormancy-breaking treatments. Final germination did not differ significantly among replicated fresh-seed treatments, reaching 80.7% after dry heat, 72.6% after simulated wildfire and 73.9% after manual scarification. Runoff scarification, interpreted descriptively because seeds were processed as a single composite batch, produced similarly high germination (78.4%). Simulated wildfire mainly accelerated germination: seeds reached 50% germination faster than after dry heat, but final germination was not higher. One-year-old seeds retained substantial viability but showed low germination after 12-h hydration, indicating that physical dormancy persisted after one year; extended hydration partly increased germination within the aged cohort. Seedling emergence was high in both establishment trials, but survival was strongly seasonal. Summer cohorts showed near-complete post-emergence mortality, whereas autumn cohorts maintained high survival after 60 days.

Conclusions

Regeneration in C. albidus is not adequately explained by strict fire dependence. Heat exposure provides a rapid dormancy-breaking cue, whereas the runoff simulation provides evidence for a plausible hydrological pathway in which seed-coat abrasion and water exposure are coupled. Fire and runoff may therefore act as complementary recruitment filters with different temporal consequences. These findings support an interpretation of C. albidus as a flexible obligate seeder whose recruitment depends on the alignment between dormancy release, hydration and post-emergence conditions. Mediterranean shrubland models should incorporate hydrological scarification, seasonal establishment bottlenecks and the increasing mismatch between fire and rainfall regimes.

Graphical Abstract