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  • Restoring the Vara de Perlilla in La Mesa, Mexico
  • Concepción Mendoza-Bautista, Fortino García-Moreno, and Dante Arturo Rodríguez-Trejo

The vara de perlilla (Symphoricarpos microphyllus), or rejagar, is a shrub found from New Mexico to Guatemala. In Central Mexico, it is found mostly in pine-oak forests and also in the true fir forests, where it blooms from July to September, produces fruits from October to December, and provides forage for wildlife such as deer. Its branches are widely used to make brooms and manufacture Christmas crafts, making this shrub an important nontimber forest product in Mexican temperate areas. Despite its resprouting ability, vara de perlilla populations are starting to decline because of overuse and deforestation or forest degradation. In other cases, the individuals exist, but they are overutilized, too young, and small, so cannot be employed when required.

Propagation and reforestation of this shrub just began a few years ago, mostly for commercial purposes. Yet its seed propagation still is not successful, and the ideal conditions for establishing this species are not well known. Its light requirements have not been studied formally. We considered light to be a key limiting factor because the species does not prosper under dense shade, but it does well under partial shade or full sun. The objective of this work was to determine appropriate light conditions for the establishment of restoration plantings with this species.

This study was carried out in La Mesa ejido, San José del Rincón municipality, in the state of Mexico (19°34′N and 100°10′W). The climate is temperate, with a mean annual precipitation of 904 mm and a mean annual temperature of 12°C, and soil is an Ocric Andosol. Cuttings were collected December 23–26, 2006 (winter, dry season, after fruit production), from local vara de perlilla populations. They were 15–20 cm long and were immediately dipped in Raizone Plus solution and planted in plastic bags filled with local pine-oak forest soil. The plants were grown in a small local forest nursery for six months. A 30% shade cloth protected the plants during five months but was removed one month before planting during the hardening phase. Irrigation was provided every other day, adjusting in case of rain, and was slightly reduced during the last month of hardening.

We planted a total of 900 six-month-old shrubs for this work: 450 small (20–35 cm length) and 450 large (45–60 cm length). Three planting sites (treatments) were chosen: oak forest (encino laurelillo, Quercus laurina, with some individuals of aile, Alnus jorullensis); six-year-old pine forest plantation (Pinus pseudostrobus, 3.5 m tall on average, 1,111 trees/ha density), on a former oak forest site; and an agricultural field cleared 20 years ago from oak forest. The treatments formed a gradient from less to more light: oak forest (1328.6 to 5224.1 MJ/m2/y), pine plantation (6388.4 to 9140.9 MJ/m2/y), and field (7050.2 to 9324.6 MJ/m2/y). The plots were approximately 150 m apart. In July 2007 during the summer rainy season, we planted 300 shrubs per treatment: 150 small and 150 large. The shrubs were planted one meter apart in six completely randomized blocks per treatment. Each block segregated 50 plants by size. To eliminate competition, grasses and forbs were removed in a circle of 1 m radius around each shrub. To measure light levels at planting time and one year later, we placed, leveled, and oriented to the north a digital camera with a hemispherical lens integrated into a frame on the three shrubs in the center of each plot to take 180° photographs toward zenith. Such hemispherical photographs were analyzed with the HemiView system (Dynamax, Houston TX), with date, latitude, longitude, and altitude to estimate direct, diffuse, and total solar radiation (MJ/m2/y) (averaged between the two observations taken in each site).


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Figure 1.

Relationship between total solar radiation (X2) and probability of mortality (P) for the vara de perlilla (Symphoricarpos microphyllus) in an oak forest in Central Mexico.

After one year...

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