Survival and reproductive fitness of two species of Pleurothallid orchids along a changing climatic gradient

Increasing periods of consecutive dry days, upward altitudinal shifts in orographic cloud formation, and increasing minimum daily temperatures occurring due to global climate change are rapidly changing the climatic parameters of cloud forests in Monteverde, Costa Rica, where hundreds of diminutive orchids thrive. In order to analyze the affect of changing microclimate on orchid fitness, two species of Pleurothallid orchids, Lepanthes eximia (Range: 1100-2050 m) and Lepanthes monteverdensis (Range: 1400-1550 m) were transplanted to plots at 1530 m, 1645 m, 1800 m. They were monitored daily for leaf, flower, and fruit production and leaf thickness. The microclimatic conditions at each site were significantly affected by elevation (ANOVA with block design; min. temp vs. elevation: F = 8.43, p = 0.001; max temp. vs. elevation: F = 0.88, p = 0.45; precipitation vs. elevation: F = 8.16, p = 0.002). Lepanthes monteverdensis responded to this changing climatic gradient with significantly higher leaf thickness (ANOVA; F = 11.67, p \u3c 0.0001) and a positive change in plant size (ANCOVA; F = 5.71, p = 0.001). Flowering in L. monteverdensis directly mirrored days with measurable precipitation as well, with these displays of increased fitness most prevalent at the mid-elevation site. A trend towards increasing mortality in L. eximia was predominant at lower elevation sites. Both species responded to microclimatic variables, suggesting that these factors are important in their survival and reproduction. With changing climatic conditions, higher elevations may now serve as a climate refuge for Pleurothallid species. Los periodos crecientes de días secos consecutivos, arriba a nivel altitudinal donde cambia la formación de las nubes orográficas, y en el incremento de la temperatura mínima diaria que ocurren debido al cambio climático global, están cambiando rápidamente los parámetros climáticos del bosque nuboso en Monteverde, Costa Rica, donde centenares de orquídeas diminutas prosperan. Para analizar el efecto del microclima cambiante en la salud de la orquídea, dos especies de orquídeas de Pleurothallid, Lepanthes eximia (La Gama: 1100-2050m) y Lepanthes monteverdensis (La Gama: 1400 – 1550m) fueron trasplantados a parcelas a 1530m, 1645m, 1800m. Fueron monitoreados diariamente por la hoja, la flor, la producción de frutas y el grosor de la hoja.https://digitalcommons.usf.edu/tropical_ecology/1545/thumbnail.jp