DOI: 10.5061/dryad.35b38
title: Data from: Microhabitat heterogeneity and a non-native avian frugivore drive the population dynamics of an island endemic shrub, Cyrtandra dentata

description: Understanding of the role of environmental change in the decline of
 endangered species is critical to designing scale-appropriate restoration
 plans. For locally endemic rare plants on the brink of extinction,
 frugivory can drastically reduce local recruitment by dispersing seeds
 away from geographically isolated populations. Dispersal of seeds away
 from isolated populations can ultimately lead to population decline. For
 localized endemic plants, fine-scale changes in microhabitat can further
 limit population persistence. Evaluating the individual and combined
 impact of frugivores and microhabitat heterogeneity on the short-term
 (i.e. transient) and long-term (i.e. asymptotic) dynamics of plants will
 provide insight into the drivers of species rarity. In this study, we used
 four years of demographic data to develop matrix projection models for a
 long-lived shrub, Cyrtandra dentata (H. St. John & Storey)
 (Gesneriaceae), which is endemic to the island of O'ahu in
 Hawai'i. Furthermore, we evaluated the individual and combined
 influence of a non-native frugivorous bird, Leiothrix lutea, and
 microhabitat heterogeneity on the short-term and long-term C. dentata
 population dynamics. Frugivory by L. lutea decreased the short-term and
 long-term population growth rates. However, under the current level of
 frugivory at the field site the C. dentata population was projected to
 persist over time. Conversely, the removal of optimum microhabitat for
 seedling establishment (i.e. rocky gulch walls and boulders in the gulch
 bottom) reduced the short-term and long-term population growth rates from
 growing to declining. Survival of mature C. dentata plants had the
 greatest influence on long-term population dynamics, followed by the
 growth of seedlings and immature plants. The importance of mature plant
 survival was even greater when we simulated the combined effect of
 frugivory and the loss of optimal microhabitat, relative to population
 dynamics based on field conditions. In the short-term (10 years), however,
 earlier life stages had the greatest influence on population growth rate.
 Synthesis and applications. This study emphasizes how important it is to
 decouple rare plant management strategies in the short versus long-term in
 order to prioritize restoration actions, particularly when faced with
 multiple stressors not all of which can be feasibly managed. From an
 applied conservation perspective, our findings also illustrate that the
 life stage that, if improved by management, would have the greatest
 influence on population dynamics is dependent on the timeframe of interest
 and initial conditions of the population.
description: Cyrtandra_dentata_matrices_2010_2014This file contains mean transition matrices from 2010–2011, 2011–2012, 2012–2013, and 2013–2014 from a geographically isolated population of a long lived shrub, Cyrtandra dentata, from the Kahanahāiki Management Unit (36 ha), located in the northern Wai‘anae Mountain Range, on the island of O‘ahu (21° 32’ N, -158°12’ W)