Rare species are important targets for biodiversity conservation efforts because rarity often equates to small populations and increased endangerment. Rare species are prone to stochastic extinction events and may be particularly susceptible to catastrophes. Therefore, understanding how rare species respond to disturbances is critical for evaluating extinction risk and guiding conservation managers. Population viability analyses (PVAs) are essential for assessing rare species' status yet they seldom consider catastrophic events. Accordingly, we present a PVA of a rare tropical epiphyte, Lepanthes caritensis (Orchidaceae), under simulated disturbance regimes to evaluate its demographics and extinction risk. We aimed to test how demographic models incorporating catastrophes affect population viability estimates. Our goal was to better guide management of these orchids and other rare plants. Results revealed L. caritensis numbers have declined recently, but projected growth rates indicated that most subpopulations should increase in size if undisturbed. Still, projection models show that moderate catastrophes reduce growth rates, increase stochasticity in subpopulation sizes, and elevate extinction risk. Severe catastrophes had a more pronounced effect in simulations; growth rates fell below replacement level, there was greater variation in projected population sizes, and extinction risk was significantly higher. PVAs incorporating periodic catastrophes indicate that rare species may have greater extinction probabilities than standard models suggest. Thus, precautionary conservation measures should be taken in disturbance prone settings and we encourage careful monitoring after environmental catastrophes. Future rare plant PVAs should incorporate catastrophes and aim to determine if rescue and reintroduction efforts are necessary after disturbances to insure long-term population viability.
Bibliographical noteFunding Information:
We genuinely thank our families and friends for their ongoing support. Special thanks to A. Sánchez-Cuervo for continual backing and assistance with fieldwork. Additional thanks to A. Hernández for help with coding. We also recognize D. Pompei, R. Kent, Y. Ferrer, P. Bracho, J. Gonzalez, and many others for aiding with fieldwork. Lastly, we sincerely thank the Círculo de Amigos de Orquidistas de Puerto Rico and the Decanato de Estudios Graduados e Investigación for providing financial support.
© 2018 The Society of Population Ecology
- Lepanthes caritensis (Orchidaceae)
- plant conservation
- Puerto Rico
- species extinction
- tropical orchid
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics