Demographic variation and conservation of the narrow endemic plant Ranunculus weyleri
2013
Cursach, Joana | Besnard, Aurélien | Rita, Juan | Fréville, Hélène
Ranunculus weyleri is a narrow endemic protected plant from Majorca Island. It is known from only five populations located in two mountain areas 48 km apart. Using demographic data collected from 2007 to 2010, we assessed the demographic status of two populations – font des Coloms (FC) and talaia Moreia (TM) – using Integral Projection Models (IPMs). We showed that none of the two populations were declining under a deterministic model. Population FC was stable (λ = 1.026, CI95% = 0.965–1.093), while population TM showed sign of demographic expansion (λ = 1.113, CI95% = 1.032–1.219). Plant survival, flowering probability and the mean number of seedlings per floral peduncle were lower in TM, whereas growth and the number of floral peduncles per reproductive plant were lower in FC. Elasticity analyses showed that management strategies increasing plant survival and growth would be the most efficient to increase λ for both populations. Herbivory pressure by goats has been shown to be high in TM, resulting in high predation rate on floral peduncles. Controlling goat pressure may thus represent a promising management option, provided that we can demonstrate a negative impact of herbivory by goats on survival and growth which are the most critical parts of the life cycle in this species. Meanwhile, initiating a long-term monitoring is of crucial importance to get more insights into the relationships between environmental variation, plant performance and population dynamics.
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