Early successional sites and the recovery of vegetation structure and tree species of the tropical dry forest in Veracruz, Mexico

Siembra directa de Brosimum alicastrum Sw. (Moraceae) y Enterolobium cyclocarpum (Jacq.) Griseb. (Mimosaceae) en diferentes habitats en el trópico seco del centro de Veracruz

“…Even though it can form part of the canopy of old growth forest it is also common in open conditions, including savannas and pastures. Its presence in forested patches is usually taken as a sign of past disturbance and it is commonly regarded as a mid to late secondary species (Blain & Kellman, 1991;Pennington & Sarukhán, 1998;Williams-Linera et al, 2011). Enterolobium seeds (15 to 20 mm in length; 10 to 12 mm wide) are mainly dispersed by ruminants, including domestic livestock and occasionally by hoarder rodents (Janzen et al, 1985); hydrochory may also be an important dispersal mechanism where flooding occurs (Enterolobium pods float; Hunter, 1989).…”

Soil seed bank, seed removal, and germination in a seasonally dry tropical forest in Veracruz, Mexico

“…A higher germination rate in sites with vegetation cover than in open areas has been found; there, high humidity and low evapotranspiration may provide more favorable microclimatic conditions (Holl, 1999;Ceccon et al, 2006;Wassie et al, 2009). Mechanical or chemical scarifi cation or other damage to seed coatings allows water absorption and promotes germination (Camargo-Ricalde and Grether, 1998;Ortega et al, 2001;Dalling et al, 2011).In central Veracruz, the seasonally dry tropical forest (SDTF) has been reduced to 7% of its original size, even though one-third of this area is secondary vegetation; previous work has indicated that the fallow period is short, usually no longer than 7-10 years, making old secondary successional sites unavailable (Williams-Linera et al, 2011). The working hypothesis were: (1) the size and composition of soil seed banks in successional sites and dry forest habitats do not mirror the aboveground vegetation, (2) the seed removal patterns of selected tree species is higher in open habitats, and (3) the germination potential of selected tree species in contrasting habitats (active pasture, successional sites and forest) will be lower in open habitats.…”

“…In this area, we selected eight study sites corresponding to different habitats: one active pasture (P1), fi ve fallows with different years of abandonment (S1-S5), and two forest fragments (F1-F2; Table 1). A detailed description of each site can be found in WilliamsLinera and Lorea (2009) and Williams-Linera et al (2011).Soil seed bank. The soil was collected from fi ve fallow sites and two forest fragments in late May 2008, just before the onset of the rainy season that triggers seed germination (Table 1).…”

“…The soil was collected from fi ve fallow sites and two forest fragments in late May 2008, just before the onset of the rainy season that triggers seed germination (Table 1). At each study site, ten soil samples (30 cm × 30 cm and 5 cm depth) were collected on plots previously established for vegetation studies (Williams-Linera and Lorea, 2009;Williams-Linera et al, 2011). The soil samples were transported to a greenhouse located on the campus of the University of Veracruz in Xalapa.…”

“…In dry forests, another important source of forest regeneration is root or stem sprouting (Vieira and Scariot, 2006); however, when propagules are available, forest recovery in open areas may occur through secondary succession (Garwood, 1989;Dalling and Denslow, 1998;Holl, 1999;Holl et al, 2000;Williams-Linera et al, 2011). The presence of propagules can be the result of seed storage in soil banks, seed rain, and the proximity to the propagule source-forest patches, isolated trees, or secondary vegetation (Holl, 1999;Zahawi and Augspurger, 1999;Wijdeven and Kuzee, 2000;Vieira and Scariot, 2006).…”