Huatulco’s Selva Seca

By Julie Etra

How many times have you heard a newbie’s surprise upon arriving in Huatulco in the dry season, which corresponds with the high tourist season, wondering what happened to the lush tropical green jungle shown on glossy brochures and websites?

What is the Selva Seca?

Welcome to the selva seca, the “dry jungle.” Huatulco has a caducifolio, or deciduous, ecosystem, an unusual semi-tropical forest in which most trees lose their leaves. Although not unique to Mexico, it is best represented in this country, and it occurs in a number of Mexican states, in particular along our beautiful Oaxacan coast. The selva seca occupies approximately 11.7% (226,898 km²) of the total area of Mexico, along the Pacific coast from southern Sonora and southwestern Chihuahua to Chiapas, continuing to Tehuantepec with small portions in the extreme south of the Baja California Peninsula and in the north of the Yucatan Peninsula. Selvas secas are generally found from sea level up to 1,500 meters, and occasionally to 1,900 meters above sea level in very dry areas.

The selva seca is described as warm-subhumid tropical – it gets HOT. As any Huatulqueño can attest, this warm climate has an average annual temperature of 27ºC (80.6ºF), a bit lower in the ‘winter’ and dry months, with approximately 330 sunny days a year. The rainy season, which dumps an average of 100 cm (over 39 inches), ends around November/December, and starts again in late May/June, preceded by a very hot, humid, and buggy period in mid-to-late April until the rains begin. Soils are typically rocky, with a poorly developed layer of organic matter.

This ecosystem can be further divided into subcategories; the selva seca on the Oaxacan coast, about 66,492 sq. km (about 24,670 sq. mi.), is described as selva baja caducifolia or selva baja espinosa caducifolia, with espinosa meaning “spiny,” as we do have a number of spiny plants and many species of cactus. In English it is also referred to as low (the baja part) deciduous forest, tropical deciduous forest, low deciduous forest, or sub-humid forest. These forests are considered evergreen when less than 25% of the species lose their leaves, sub-evergreen when 25 to 50% of the species lose their leaves, sub-deciduous (50 to 75% of the species lose their leaves) or deciduous (more than 75% of the species lose their leaves). Since more than 75% of the coastal trees lose their leaves, the coast of Oaxaca is best defined in English as deciduous.

Plant Life of the Selva Seca

This forest has approximately 6,000 species of plants, of which almost 40 are endemic, meaning they are only found in these ecosystems and are adapted to drought.

The height of the dominant woody vegetation is often 15 meters or less (under 50 feet) for the selva baja. In addition to trees, this ecosystem supports a variety of shrubs, lianas (vines), epiphytes (the pinkish pineapple-like piñuela seen in the planting beds of many of the medians on major roads) and agaves.

Small trees include the huaje or guaje (Leucaena leucocephala), for which Oaxaca was named (it means “place where the huaje grows”), which produces a pea-like pod replete with peas. Some trees like the cuachalalá or cuachalalate (Amphipterygium adstringens), whose bark is used for medicinal purposes, drop their leaves at the very beginning of the dry season – snowbirds never get to see the leaves.

The guanacastle or guanacaste (Enterolobium cyclocarpum), Huatulco’s magnificent huge shade tree, welcomes visitors and residents en route from highway 200 to Huatulco, along the median just south of the Fonatur logo. In early to mid-April, the guanacastles exhibit new bright green leafy growth, having detected the increase in ambient humidity.

There are at least five species of copal (Bursera spp.), all of which drop their leaves in winter. One species, known commonly as mulato, has the gorgeous flakey red bark so visually outstanding in the native forest. Copal trees produces a resin which hardens into incense used in spiritual ceremonies for centuries; the bark apparently also produced pigments for painting the ancient ruins of Mexico. Most people who visit Mexico, however, will encounter the wood of a copal tree when they purchase an alebrije, the colorful, fanciful figures carved and painted by Mexical folk artists.

What Stays Green in the Selva Seca?

Of course, not all our native species fall into the 75% deciduous category (by the way, coconut palms are not native, but we do have a native palm, the sabal Mexicana whose pencas (fronds) are used in palapa construction). Riparian corridors stay green, the shrubby ocotillo (Fouquieria splendens or madcogalii), with its white or red flowers, respectively, is barely deciduous, and the ceiba tree, also called pochote, can look a little ratty, but not for long.

The Best of the Selva Seca

What I especially love about the dry season is the number of trees that flower! We have three species of macuil (Tabebuia rosea) with their big, showy purple, pink, and yellow flowers, the guayacán (Guaiaccum coulteri)with its yellow-centered purple flowers, and the magnificent cojón de caballo or cojón de toro (Tabernaemontana donnell-smithii), its large yellow flower appearing early in the winter, contrasting with its smooth white/silvery bark. Translated, as you might guess, as the horse- or bull-ball tree, it is named for the shape of its fruit, which grows in pairs.

The final benefit of being in the selva seca in the dry season is the birdlife, both residents and winter migrants. They are so much easier to see and identify in the less leafy landscape, making this area a winter birder’s paradise!