Plant Demography

Creating self-sustaining populations resilient to stochastic events is the goal of conservation reintroductions. Concern about disrupting locally co-adapted gene complexes, outbreeding depression, and hybridization has led to a “local is best paradigm” for source selection, yet this policy constrains rare plant reintroduction efforts and may not always best conserve rare species. Using progeny from controlled crosses (control, selfed, near neighbor, far neighbor and between sites) with maternal plants from two sites, we tested survival and population trajectories of US endangered Jacquemontia reclinata reintroduced in 2004 and 2005 to three sites. By 2011, survival and recruitment was greatest for mixed-population progeny, was consistent across years, and became most apparent after extreme climate events (hurricanes, drought, and exceptional cold). Populations founded from mixed sources exhibited greater resilience to stochastic disturbances than those from a single source and had positive projected population growth at two of three sites. Recipient sites most proximal to maternal origin were not those with best survival. Maximizing reintroduced population persistence calls for re-examining paradigms, using decision trees and reintroduction guidelines to guide source selection choices. The local is best paradigm may be dooming many reintroductions to failure.

RESUMEN. Acoelorraphe wrightii H. Wendl es una palma nativa de América Central, el Caribe y el sur de la Florida. En Cuba se utiliza en la carpintería rural, principalmente como postes de cerca, lo que podría afectar la dinámica de sus poblaciones. Debido a ello, en este trabajo se caracteriza la dinámica de una población de A. wrightii y el posible impacto de su uso. Se determinaron y cuantificaron en cinco transectos de 50 x 5 m to-das las colonias como unidades genéticas (genets) y cada vástago (ramets) por genet, identificando aquellos en estado reproductivo. Se estimó el tamaño poblacional y construyeron tablas de vida tiempo-específicas. La densidad y tamaño poblacional son altos, con un estimado de más de tres millones de ramets. Sin embargo , solo se encontraron dos ramets mayores de 3,60 m y el tamaño medio fue de 2,52 m, a pesar de que la especie fue descrita con un máximo de 5 m en condiciones similares. Las tablas de vida mostraron dos picos de mortalidad, uno entre las plántulas y otro entre los adultos de entre 1,8 y 3 m de altura, altura en que co-mienzan a ser utilizados. Asimismo, se encontró una relación significativa entre la altura de los individuos y su capacidad reproductiva. Las presiones extractivas que sufren actualmente los ramets parece estar afectando la capacidad reproductiva de la población. A pesar del gran tamaño poblacional, la sobreexplotación de los individuos reproductivos señala la necesidad de establecer estrategias para el uso sostenible de los mismos. Palabras clave: demografía, tablas de vida tiempo específico, uso sostenible. ABSTRACT. Acoelorraphe wrightii H. Wendl is a palm native to Central America, the Caribbean and South Florida. In Cuba it is used in rural carpentry, primarily as fence posts, which could affect the dynamics of their populations. Because of this, in this work the dynamics of a population of A. wrightii and the potential impact of their use is characterized. They were identified and quantified in five transects 50 x 5 m all colonies as genetic units (genets) and each rod (ramets), identifying those in reproductive status. The estimated population size and life tables constructed time-specific. The population density and size are high, with an estimated more than three million ramets. However, only two top ramets to 3.60 m were found, but the average size was 2.52 m, although the species was described with a maximum of 5 m in similar conditions. Life tables of mortality showed two peaks, one between seedlings and other adults between 1.8 and 3 m in height, height they begin to be used. Also, a significant relationship between the height of individuals and their reproductive capacity is found. The cuts suffered by ramets seem to be affecting the reproductive capacity of the population. Despite the large population size, the overexploitation of reproductive individuals highlights the need to develop strategies for sustainable use.

Patterns of phenological variation and reproductive investment were studied in the dioecious shrub Baccharis dracunculifolia DC (Asteraceae), and possible consequences on survivorship were evaluated. The sex ratio was determined in a natural field population (n = 921) of B. dracunculifolia in Belo Horizonte, Brazil. Fifty-two males and 56 females were sampled at random from this population. During the reproductive season of 1999, inflorescence production, shoot growth and mortality, and xylem water potential were recorded for each individual. The population sex ratio was male-biased (1.27 : 1, P < 0.05), and was associated with a higher mortality of female shoots (38.4 vs. 23.1 %, P < 0.05), and individuals (17.8 vs. 11.5 %, P < 0.1), despite lower water stress in female plants. Flowering phenology also differed between the sexes, with males producing more inflorescences, and earlier, than females. Owing to fruit maturation, the number of inflorescences supported by females...