The influence of natural fire and cultural practices on island ecosystems: Insights from a 4,800year record from Gran Canaria, Canary Islands

Ravazzi, Cesare; Mariani, Michela; Criado, Constantino; Garozzo, Lorena; Naranjo-Cigala, Agust�n; Perez-Torrado, Francisco J.; Pini, Roberta; Rodriguez-Gonzalez, Alejandro; Nogu�, Sandra; Whittaker, Robert J.; Mar�a Fern�ndez-Palacios, Jos�; de Nascimento, Lea

Abstract

Aim: Long-term ecological data provide a stepped frame of island ecosystem transformation after successive waves of human colonization, essential to determine conservation and management baselines. However, the timing and ecological impact of initial human settlement on many islands is still poorly known. Here, we report analyses from a 4800-year sedimentary sequence from Gran Canaria (Canary Islands), with the goal of disentangling forest responses to natural fire from early human pressure on the island. Location: La Calderilla, a volcanic maar caldera at 1,770m a.s.l. on Gran Canaria. Taxon: Plants and fungi. Methods: A core from the caldera infill was analysed for sediment properties, pollen, micro- and macrocharcoal, with radiocarbon and biochronology dating. Fossil data were statistically zoned and interpreted with the help of cross-correlation and ordination analyses. Surface samples and a pollen–vegetation training set were used as modern analogues for vegetation reconstruction. Results: Before human settlement (4,800–2,000cal. yr bp), pine (Pinus canariensis) pollen dominated. Extensive dry pine forests characterized the highlands, although with temporary declining phases, followed by prompt (sub-centennial scale) recovery. Towards 2,280cal.yrbp there was a shift to open vegetation, marked by an increase in coprophilous spores. Coincidental with independent evidence of human settlement in the pine belt (2,000–470cal. yr bp) there was a decline of pine and a peak in charcoal. Following historic settlement (470–0cal. yr bp), pollen producers from anthropogenic habitats, secondary vegetation and coprophilous fungi increased in abundance, reflecting higher pressure of animal husbandry and farming. Modern moss polsters reflect extensive reforestation since 1950 ce (Common Era). Main conclusions: From 4,800cal. yr bp, the pristine vegetation covering the Gran Canaria highlands was a mosaic of dry pine forests and open vegetation. The pine forests sustained intense fires, which may well have promoted habitat diversity. Human interference was initiated around 2,280cal. yr bp probably by recurrent cultural firing and animal husbandry, triggering a steady trend of forest withdrawal and expansion of grasses and scrubs, until the final disappearance of the pine forest locally in the 20th century. Grasslands were found to be of ancient cultural origin in the summit areas of Gran Canaria, although they underwent an expansion after the Castilian Conquest.

Citation

Ravazzi, C., Mariani, M., Criado, C., Garozzo, L., Naranjo-Cigala, A., Perez-Torrado, F. J., Pini, R., Rodriguez-Gonzalez, A., Nogué, S., Whittaker, R. J., María Fernández-Palacios, J., & de Nascimento, L. (2021). The influence of natural fire and cultural practices on island ecosystems: Insights from a 4,800year record from Gran Canaria, Canary Islands. Journal of Biogeography, 48(2), 276-290. https://doi.org/10.1111/jbi.13995

• Journal Article Type: Article
• Acceptance Date: Sep 1, 2020
• Online Publication Date: Nov 21, 2020
• Publication Date: 2021-02
• Deposit Date: Sep 16, 2020
• Publicly Available Date: Nov 22, 2021
• Journal: Journal of Biogeography
• Print ISSN: 0305-0270
• Electronic ISSN: 1365-2699
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 48
• Issue: 2
• Pages: 276-290
• DOI: https://doi.org/10.1111/jbi.13995
• Keywords: ancient grasslands, fire ecology, forest disturbance, human impact, island ecology, palaeoecology, Pinus canariensis, reforestation
• Public URL: https://nottingham-repository.worktribe.com/output/4906136
• Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1111/jbi.13995
• Additional Information: This is the peer reviewed version of the following article: Ravazzi, C., Mariani, M., Criado, C., Garozzo, L., Naranjo-Cigala, A., Perez-Torrado, F. J., …de Nascimento, L. (2020). The influence of natural fire and cultural practices on island ecosystems: insights from a 4800 year record from Gran Canaria, Canary Islands. Journal of Biogeography, which has been published in final form at https://doi.org/10.1111/jbi.13995. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.