Abies hickelii (Hickel fir) description

Abies hickelii

Flous et Gaussen 1932

Common names

Hickel's fir; oyamel, pinabete [Mexican Spanish] (Farjon 2010).

Taxonomic notes

Syn: A. religiosa (Kunth) Schlechtendahl et Chamisso subsp. hickelii (Flous et Gaussen) K. Strandby, K.I. Christensen, et M. Sørensen 2009.

There are two varieties, the type and A. hickelii Flous et Gaussen var. oaxacana (Martinez) Farjon et Silba 1990 (syn.: Abies oaxacana Martinez 1948; Abies hickelii Flous et Gaussen var. macrocarpa Martinez 1942.

Aguirre-Planter et al. (2000) studied genetic variability in the southern Mexican firs, Abies flinckii, A. guatemalensis, A. hickelii, and A. religiosa, and found that they all have low genetic diversity within populations, suggesting that they have each experienced genetic bottlenecks during their retreat to their current interglacial refugia (a biogeographic situation which also puts them at extreme risk from global warming). They also show high diversity between populations, supporting their treatment as separate taxa. See A. flinckii for more discussion of recent (2008-2020) developments in molecular taxonomy of this group, which has established A. hickelii as sister to an A. flinckii+A. jaliscana clade.

Description

Trees to 30 m tall and 130 cm dbh, usually with a single, straight, round trunk, often clear for a good part of the tree's height; crown narrowly conical, less regular in old trees. Bark of at first smooth, gray, thickening with age and breaking up into quadrangular plates. Branches spreading horizontally, then ascending. Branchlets slender, purple- or red-brown, grooved, glabrous or slightly pubescent, with small, ovate or round leaf scars. Foliar buds ovoid, 5 x 4 mm, resinous; bud scales triangular, brown, persisting several years. Leaves on sun foliage angled forward; on shade foliage spirally arranged but appearing 2-ranked, diverging at nearly right angles to shoot, of about equal length; 18-35 × 1-1.8 mm, twisted or curved at base, shiny light green above, glaucous below; apex emarginate (sometimes obtuse). Stomata in two bands separated by a midrib below, none or a few near apex above. Pollen cones lateral, short, yellow with red microsporophylls. Seed cones lateral, erect, short pedunculate, oblong-cylindrical, with obtuse apex, 6-8 × 2.5-3.5 cm, purple ripening dark brown; rachis persistent, dark brown. Seed scales cuneate, 14 × 19 mm (at mid-cone); smooth, variably hairy; outer margin rounded, entire. Bracts 2 cm long, exserted. Seeds 6-7 mm long, light brown, with a light brown 10 x 8 mm wing (Farjon 2010).

The type and var. oaxacana are distinguished by the size of the seed cones; 6-8 × 2.5-3.5 cm in the type, and 9-12 × 5 cm in var. oaxacana (Farjon 2010).

Distribution and Ecology

S Mexico: Guererro, Oaxaca, and Chiapas at 2500-3000 m elevation. Climate cool, oceanic, winter-wet. Soils volcanic. Occasionally in pure stands (at the highest elevations), but usually in mixed stands; associates include Pinus montezumae, P. pseudostrobus, P. ayacahuite, Hesperocyparis lusitanica and Quercus spp., above a shrub layer that may include Vaccinium spp., Andromeda spp., Ribes spp., and Fuchsia spp. (Farjon 2010). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001).

Habitat and distribution are the same for the type and var. oaxacana, except that var. oaxacana has not been described from Chiapas (Farjon 2010).

This species is listed as endangered in Mexico under NOM-ECOL-059-94. The IUCN lists both the species and both subspecies, separately, as "endangered."

Remarkable Specimens

No data as of 2023.11.25.

Ethnobotany

In habitat, this rare species is seldom and then incidentally harvested for timber. It is rare in cultivation, largely limited to botanical gardens in areas with a warm-temperate climate. Its use in dendrochronology includes one study performed in Oaxaca (Naylor 1971) that found generally unsatisfactory results: all sampled trees were young, complacent, and could not be crossdated. This finding was attributed to an insufficiently seasonal climate.

Observations

No data as of 2023.11.25.

Remarks

The epithet commemorates the French botanist R. Hickel.

Citations

Aguirre-Planter, Erika, Glenn R. Furnier, and Luis E. Eguiarte. 2000. Low levels of genetic variation within and high levels of genetic differentiation among populations of species of Abies from southern Mexico and Guatemala. American Journal of Botany 87:362-371.

Flous and Gaussen. 1932. Trav. Lab. Forest. Toulouse T. I (1, 17): 1.

Naylor, T.H. 1971. Dendrochronology in Oaxaca, Mexico: a preliminary study. Tree-Ring Bulletin 31:25-29.

Strandby, U., K.I. Christensen, and M. Sørensen. 2009. A morphometric study of the Abies religiosa–hickelii–guatemalensis complex (Pinaceae) in Guatemala and Mexico. Plant Systematics and Evolution 280:59-76.