Recovery and early succession after experimental disturbance in a seasonally dry tropical forest in Mexico

We studied succession over five years in a seasonally dry tropical forest in Quintana Roo, Mexico, following three different types of experimental disturbance (slashing and complete felling; slashing, felling and burning; and machine-clearing), each one implemented in 1996 on two 0.5 ha treatment plots. Before experimental disturbances, the floristic composition, dominance and diversity of the forest vegetation had been determined. In 1997, after treatments were applied, a second survey characterized early secondary vegetation at one year. A third survey was conducted in 2001. The 1996 vegetation composition revealed no significant differences among the six treatment plots. In 1997, floristic composition on the six treatment plots showed differences in dominance and diversity: the post-treatment vegetation on the slash/fell treatment was clearly distinct from that on the other two treatments. In 2001, differences among the plots had decreased considerably. Comparisons among seral stages revealed that one-year-old secondary vegetation differed from the pre-disturbance original vegetation, while five-year-old vegetation was similar to the original in its diversity, floristic composition and dominance. Felling alone favors species with a high resprouting capacity. The frequency of species with resprouting capacity was lower on slash/fell/burn treatments and lowest on machine-cleared plots. Results indicate that the effect of disturbance tends to decline over time and that complete clearing of small areas is effective as a silvicultural treatment to favor regeneration of valuable timber species and sustain diversity.