Recurrent wildfires constrain long-term reproduction ability in Pinus halepensis Mill.

Josep Maria Espelta; Iraima Verkaik; Màrcia Eugenio; Francisco Lloret

doi:10.1071/WF07078

RESEARCH ARTICLE

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Recurrent wildfires constrain long-term reproduction ability in Pinus halepensis Mill.

Josep Maria Espelta ^A ^B , Iraima Verkaik ^A , Màrcia Eugenio ^A and Francisco Lloret ^A

+ Author Affiliations

- Author Affiliations

^A CREAF (Center for Ecological Research and Forestry Applications) and Unit of Ecology, Department of Animal and Plant Biology and Ecology, Autonomous University of Barcelona, E-08193 Bellaterra (Catalonia), Spain.

^B Corresponding author. Email: josep.espelta@uab.es

International Journal of Wildland Fire 17(5) 579-585 https://doi.org/10.1071/WF07078
Submitted: 6 June 2007 Accepted: 11 December 2007 Published: 3 October 2008

Abstract

Increasing fire recurrence is a major problem threatening Mediterranean-type ecosystems. Moreover, this pattern is predicted to increase owing to global change. Although a reduction in the density and growth of post-fire regeneration is usually observed in recurrently burnt areas, the potential effects on reproductive ability have seldom been explored. The aim of the present study is to investigate whether structural changes induced by fire recurrence may constrain reproduction ability of Pinus halepensis forests. We conducted the current study in Catalonia (NE Spain) in 12 study sites, consisting of two adjacent areas differing in the number of fire events suffered throughout the last 16 years (one v. two fires). Twice-burnt areas showed a lower density of pines, lower pine height and a lower reproductive ability, namely (i) a 3-year delay in the onset of pine reproduction; (ii) a reduction of 52% in the number of reproductive pines; and (iii) a 36% lower mean cone crop per tree. The lower mean cone production per tree coupled with a lower density resulted in an ~80% lower canopy seed bank in twice-burnt areas. These results suggest that the occurrence of a third fire event in twice-burnt areas would severely constrain natural regeneration.

Additional keywords: canopy seed bank, Mediterranean-type climate, post-fire obligate seeder, serotiny.

Acknowledgements

Thanks are due to José Luis Ordóñez for field assistance and to Rebeca Izquierdo and Helena Barril for laboratory measurements of cone and seed samples. Two anonymous reviewers provided helpful comments on an early draft of this manuscript. The present research was partly funded by the I3A-1–100-E project from the Interreg III A program (EU) and the REN2003–07198-C02–01/G10 project from the Spanish Ministerio de Ciencia y Tecnología.

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**Appendix 1. Main topographical and structural characteristics of the study sites**
r1, once-burnt areas; r2, twice-burnt areas

Appendix 2. Age of first reproduction, proportion of reproductive pines, degree of serotiny and mean number of cones (open, serotinous, mature, immature and current-year cones) in the 30 randomly selected pines on the study sites
r1, once-burnt area; r2, twice-burnt area. The degree of serotiny is the ratio between the number of mature and serotinous cones closed and the total number of mature and serotinous cones (closed + opened)

Recurrent wildfires constrain long-term reproduction ability in Pinus halepensis Mill.

Abstract

Acknowledgements

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