Epiphytes are one of the most ubiquitous elements of tropical forest canopies, including seasonally dry tropical forests. Given the temporal variation in weather conditions in the latter, epiphyte populations may be subject to wide temporal variation in seedling recruitment, reproductive success, vegetative propagation and mortality rate. In this study, we use a 3-y demographic data set for Tillandsia brachycaulos to project its long-term population dynamics through the use of average and periodic matrices, as well as stochastic simulations. The results show that demographic behaviour varied over the 3 years of study, apparently in relation to rainfall. The first 2 years yielded a low λ value (0.79 and 0.80 – although only the former was significantly lower than unity), while the third year resulted in a λ = 1.08 (not significantly different from 1.0). When incorporating this demographic variation in an average matrix, a periodic matrix and stochastic simulations, the resulting overall λ was below unity in all three cases. The projections of the stochastic simulations suggest that the population would be able to persist in the long run only if the frequency of “good” years (defined here as those with an August rainfall above 200 mm) was above 0.6, which appears unlikely given that global warming might result in a lower frequency of rainy years in tropical dry forests.

A crucial need for population maintenance of epiphytic species is the location of suitable microsites on a host tree. Quantitative evaluation of epiphyte seed dispersal and germination is needed to more fully understand successful host colonization; this process is especially important in dry forests, where drought and oligotrophy diminish population growth rates. In a 3-year field experiment, we evaluated seed dispersal and germination of Tillandsia brachycaulos and explored some environmental factors affecting these life-cycle phases. There was significant variation in dispersal curves depending on year and height of seed release. Forty-one percent of seeds experimentally released were not dispersed and only ca. 0.5% of dispersed seeds were captured in seed traps. The number of trapped seeds decreased with distance; most seeds were captured within 1.5 m of the seed source. Seeds dispersed farther (15 m) when released from greater heights. Seed germination under controlled conditions (98%) was h... Resumen Una necesidad crucial para el mantenimiento de las poblaciones de especies epífitas es la localización de micrositios adecuados en el árbol hospedero. Se necesita una evaluación cuantitativa de la dispersión y germinación de semillas de las epífitas del epífita para entender mejor la colonización exitosa; dicho proceso es particularmente importante en bosques secos, donde la sequía y la oligotrofía disminuyen las tasas de crecimiento poblacional. En un experimento de campo durante tres años, evaluamos la dispersión y germinación de semillas de Tillandsia brachycaulos y exploramos algunos factores ambientales que afectan estas fases del ciclo de vida. Las curvas de dispersión mostraron una variación significante, dependiendo en el año y la altura de la liberación de las semillas. El 41% de las semillas liberadas experimentalmente no fueron dispersadas y solamente cerca del 0.5% de las semillas dispersadas fueron capturadas en trampas de semillas. El número de semillas capturadas disminuyó a medida ...

Illegal wildlife trade represents a global conservation priority, but the booming illegal trade in wild plants remains understudied. We use the Mexican orchid trade to illustrate an interdisciplinary approach to provide novel insight on conservation strategies and policies. We synthesize studies of orchid markets, national orchid confiscation records, CITES registers, and global population dynamics studies to document trade patterns and potential ecological impacts. We found 333 wild‐harvested orchid taxa illegally traded in domestic markets. Clear patterns emerged: 90% were epiphytic and <4% traded in high volumes, all of which had pseudobulbs and bloomed during cultural festivals. Most sales were pseudobulbs, not whole plants. Review of demographic studies indicates whole‐plant harvest is unviable but simulations show potential for sustainable harvest of pseudobulbs. The combination of social and ecological findings suggests a novel multipronged approach to improve conservation, including selective monitoring, enforcement focused on whole‐plant harvest, and community‐based wild harvest of pseudobulbs.