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.

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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 communitybased wild harvest of pseudobulbs. K E Y W O R D Sconservation policy, illegal wildlife trade, matrix models, Mexico, orchids, social-ecological systems Conservation Letters. 2020;13:e12697.wileyonlinelibrary.com/journal/conl

Hundreds of epiphytic bromeliads species are harvested from the wild for trade and for cultural uses, but little is known about the effects of this harvest. We assessed the potential demographic effects of harvesting from the wild on 2 epiphytic bromeliads: Tillandsia macdougallii, an atmospheric bromeliad (adsorbs water and nutrients directly from the atmosphere), and T. violaceae, a tank bromeliad (accumulates water and organic material between its leaves). We also examined an alternative to harvesting bromeliads from trees--the collection of fallen bromeliads from the forest floor. We censused populations of T. macdougallii each year from 2005 to 2010 and of T. violaceae from 2005 to 2008, in Oaxaca, Mexico. We also measured monthly fall rates of bromeliads over 1 year and monitored the survival of fallen bromeliads on the forest floor. The tank bromeliad had significantly higher rates of survival, reproduction, and stochastic population growth rates (λ(s) ) than the atmospheric bromeliad, but λ(s) for both species were <1, which suggests that the populations will decline even without harvest. Elasticity patterns differed between species, but in both, survival of large individuals had high elasticity values. No fallen bromeliads survived more than 1.5 years on the forest floor and the rate of bromeliad fall was comparable to current harvest rates. Low rates of population growth recorded for the species we studied and other epiphytic bromeliads and high elasticity values for the vital rates that were most affected by harvest suggest that commercial harvesting in the wild of these species is not sustainable. We propose the collection of fallen bromeliads as an ecologically and, potentially, economically viable alternative.