Preliminary results on the effects of the California poppy ( Eschscholzia californica Cham.) and the Fairy crassula ( Crassula multicava Lem.) on the island of Tenerife (Canary Islands)

Abstract

Due to their distinctive ecosystems and the presence of endemic species with restricted ranges, archipelagos are particularly vulnerable to emerging threats like invasive species. This research project aims to assess the invasive potential of the California poppy ( Eschscholzia californica) and the pink crassula ( Crassula multicava) on the island of Tenerife, Canary Islands. The California poppy, native to North America, was introduced to the Canary Islands as an ornamental plant during the 19th century. It is commonly found along paved areas and clearings within the Canarian pine forest. The pink crassula, native to South Africa, was introduced during the 20th century and thrives in Canarian laurel forest areas near urban settlements. The main objective of this project is to map and monitor the populations of these species on the island of Tenerife, determine their responses to different environmental conditions, as well as to various eradication treatments, and assess their invasive impact on native and/or endangered flora. Fieldwork has shown a broader than previously thought distribution of both species, with increasing populations observed in new areas. In addition, 30% of the records show direct competition with other plant species, while 17% demonstrate competition with endemic species. Eschscholzia californica reproduces effectively through sexual means, establishing a long-term seed bank. Crassula multicava establishes itself successfully through vegetative multiplication, easily invading areas through the fall of propagules. Both species have shown a capacity to form new seedlings continually, making eradication efforts challenging. These findings indicate a high invasive potential for both species on Tenerife, underlining the need for effective management and control measures to prevent further spread. In conclusion, this research highlights the growing concern over these invasive species and their impact on Tenerife’s ecosystems, emphasizing the importance of ongoing monitoring and intervention.