Quercus costaricensis Liebm.  

Habitat and Ecology

Systems

• Terrestrial

Year Assessed

• Needs updating

Assessor/s

Reviewer/s

• 1998
  Vulnerable (V)

The Costa Rican black oak (Quercus costaricensis) is one of the most dominant species in the upper montane forests of Costa Rica (Guariguata & Saenz 2002). It can grow up to 30m tall and reach 1m in diameter (Gargiullo et al. 2008). Mature trees are characterized by rough, fissured bark and leathery, rounded leaves (Gargiullo et al. 2008). Leaves are leathery, stiff and typically large, reaching up to 10cm in length, with a shiny upper surface and an underside covered in short, dense hairs (Gargiullo et al. 2008). Flowers are small and inconspicuous, usually yellowish or green (Gargiullo et al. 2008). Flowers are single sex, but trees are monoecious, meaning both male and female flowers can be found on a single plant (Gargiullo et al. 2008). Fruits are large acorns up to 3cm long (Burger 1983).

Quercus costaricensis is endemic to the upper montane oak forests of the Cordillera de Talamanca, or the Talamanca mountain range of Costa Rica and Panama (Guariguata & Saenz 2002). It often occurs in areas of oak-bamboo forest, with bamboo species such as Chusquea spp. forming the understory layer (Guariguata & Saenz 2002). Q. costaricensis has one of the highest elevational ranges of any Quercus (Vindas & Quesada 2003). It is the dominant species at elevations between 2700m and 3300m, but can be found anywhere between 2000m and 3600m (Burger 1983). As the prevailing species of these higher altitudes, it plays an important role in the prevention of soil erosion and retention of moisture in these ecosystems (Guariguata & Saenz 2002).

Q. costaricensis exhibits an interesting reproductive cycle, with some unique adaptations to prevent excessive herbivory. An entire population of Q. costaricensis will flower synchronously every three to four years in what is called a mast flowering event, or simply masting event (Guariguata & Saenz 2002). Because this species is wind-pollinated, synchronous flowering increases the likelihood of pollination for all individuals (Nixon 2004). After pollination, the fruits take two full growing seasons to mature, in what is called biennial fruiting (Nixon 2004). The flowering event occurs most often in the dry season, so that fruits may be ready for the wet season of the year after, in order to ensure sufficient water for the successful germination of the seed (Nixon 2004). Such a mast fruiting event may be an adaptation to prevent excessive herbivory through herbivore satiation (Burger 1983). Large quantities of fruit fall at once, so that herbivores cannot possibly consume all of them and many are left to germinate (Burger 1983). Seeds are mainly dispersed by squirrels, which will cache the acorns and leave some caches forgotten, or birds, which may carry and drop the seeds (Nixon 2004).

The Q. costaricensis population is currently recovering after a previous decline caused by excessive logging (Burger 1983). The dense wood of this species means the timber is especially prized for slow-burning charcoal, and was used widely by locals for cooking throughout the 19th and 20th centuries (Burger 1983).

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