Germination response to winter temperature changes with seed shape and length of temperature exposure.

In many regions, the climate is changing faster during winter than during the other seasons, and a loss of snow cover combined with increased temperature variability can expose overwintering organisms to harmful conditions. Understanding how species respond to these changes during critical developmental times, such as seed germination, helps us assess the ecological implications of winter climate change. To address this concern, we measured the breaking of seed dormancy and cold tolerance of temperate grassland species in the lab and field. In the lab, we ran germination trials testing the tolerance of 17 species to an extreme cold event. In the field, we deployed seeds of two species within a snow manipulation experiment at three locations and measured germination success biweekly from seeds subjected to ambient and reduced snow cover from winter into spring. From lab trials, cold tolerance varied among species, with seed germination decreasing <10%-100% following extreme cold events. Cold tolerance was related to seed traits, specifically less round seeds, seeds that required cold stratification, and seeds that mature later in the season tended to be more impacted by extreme cold temperatures. This variation in seed cold tolerance may contribute to altered community composition with continued winter climate change. In the field, germination increased through late winter, coinciding with the accumulation of days where temperatures were favorable for cold stratification. Through spring, germination success decreased as warm temperatures accumulated. Collectively, species-specific seed cold tolerances and mortality rates may contribute to compositional changes in grasslands under continued winter climate change.

Plant trait and vegetation data along a 1314 m elevation gradient with fire history in Puna grasslands, Perú.

Alpine grassland vegetation supports globally important biodiversity and ecosystems that are increasingly threatened by climate warming and other environmental changes. Trait-based approaches can support understanding of vegetation responses to global change drivers and consequences for ecosystem functioning. In six sites along a 1314 m elevational gradient in Puna grasslands in the Peruvian Andes, we collected datasets on vascular plant composition, plant functional traits, biomass, ecosystem fluxes, and climate data over three years. The data were collected in the wet and dry season and from plots with different fire histories. We selected traits associated with plant resource use, growth, and life history strategies (leaf area, leaf dry/wet mass, leaf thickness, specific leaf area, leaf dry matter content, leaf C, N, P content, C and N isotopes). The trait dataset contains 3,665 plant records from 145 taxa, 54,036 trait measurements (increasing the trait data coverage of the regional flora by 420%) covering 14 traits and 121 plant taxa (ca. 40% of which have no previous publicly available trait data) across 33 families.

Beach almond (Terminalia catappa, Combretaceae) seed production and predation by scarlet macaws (Ara macao) and variegated squirrels (Sciurus variegatoides) / Producción de semillas y depredación del almendro de playa (Terminalia catappa, Combretaceae) por lapas rojas (Ara macao) y ardillas chizas (Sciurus variegatoides)

Knowledge of ecological impacts of exotic beach almond (Terminalia catappa) in the central Pacific of Costa Rica are little known, but studies have found this species to be a potentially important food source for endangered scarlet macaws (Ara macao). In this study, reproductive phenology and seed predation by variegated squirrels (Sciurus variegatoides) and scarlet macaws were measured during March and April 2011 on beaches of central Pacific coastal Costa Rica. Seed productivity and predation levels were quantified on a weekly basis for 111 beach almond trees to assess the importance of beach almond as a food source for scarlet macaws and the extent of resource partitioning between seed predators. Seed production of the trees was great (about 194 272 seeds) and approximately 67% of seeds were predated by seed predators. Macaws consumed an estimated 49% of seeds while squirrels consumed 18%. Additionally, evidence of resource partitioning between squirrels and macaws was found. Scarlet macaws preferred to feed on the northern side and edge of the canopy while squirrels preferred to feed on the southern and inside parts of the canopy. Both species ate most seeds on the ocean side of the tree. Despite the status of this tree as an exotic species, the beach almond appears to be an important resource for scarlet macaw population recovery. The resource produced by this tree should be taken into account as reforestation efforts continue in Costa Rica. Rev. Biol. Trop. 62 (3): 929-938. Epub 2014 September 01.

El conocimiento de los impactos ecológicos del almendro de playa exótico (Terminalia catappa) en el Pacífico Central de Costa Rica son poco conocidos, pero los estudios han encontrado que esta especie es una fuente de alimento potencialmente importante para la lapa roja (Ara macao), en peligro de extinción. En este estudio, se midieron la fenología reproductiva y la depredación de semillas por las ardillas (Sciurus variegatoides) y lapas rojas durante marzo y abril 2011 en las playas de la costa Pacífica Central de Costa Rica. Los niveles de productividad y depredación de semillas se cuantificaron semanalmente para 111 almendros de playa, para evaluar la importancia del almendro de playa como fuente de alimento para la lapa roja y el grado de repartición de recursos entre los depredadores de semillas. La producción de semillas de los árboles fue alta (cerca de 194 272 semillas) y aproximadamente el 67% de las semillas fueron comidas por los depredadores, las lapas rojas consumen un estimado de 49% de las semillas, mientras que las ardillas consumen el 18%. Adicionalmente, se encontró evidencia de la repartición de recursos entre las ardillas y las lapas. Las lapas rojas prefieren alimentarse en el lado norte y el borde de la copa, mientras que las ardillas prefieren las regiones del sur y el interior de la copa. Ambas especies se comieron la mayoría de las semillas en la parte del árbol con lado al mar. A pesar de la situación de este árbol como una especie exótica, la playa de almendras parece ser un recurso importante para la recuperación de la población de lapas rojas. El recurso que produce este árbol debe tomarse en cuenta para continuar con los esfuerzos de reforestación en Costa Rica.