Effect of fire on growth of three perennial grasses from central semi-arid Argentina

摘要

The efleet of fire on growth of Piptochaetium napostaense, Stipa tenuis, and Stipa gynerioides, three important native perennial grasses in the semi-arid region of central Argentina, was evaluated under different fire temperature regimes: 300-400℃ (low temperature regime), 500-600℃ (high temperature regime) and no fire (eontrol). Fire treatments were applied with a portable propane plant burner in April and December 1994, May 1995, and January 1996. Overall results indicate that during the first months after fire occurrence, average total green length of S. tcnuis, P. napostaeme and S. gynerioides tillers was severely reduced (p<0.05) by fire. This effect was more pronounced in plants burned with the high temperature treatment. The observed patterns of response to fire for height of tillers were very similar to those already reported for total green length of tillers. Towards the end of each growth cycle, the number of green leaves per tiller of burned plants of P. napostaense, S. tenuis, and S. gynerioides were similar or greater (p < 0.05) than the number of green leaves on tillers of eontrol plants. Relative growth rates for total green length and for height in tillers of burned plants of S. tenuis, P. napostaense and S. gynerioides were greater than in tillers of control plants. Our results indicate that fire affected differentially the growth of the studied species; S. gynerides was more affected by fire than P. naposlaense and S. tenuis. The species most tolerant to fire was P. napostaense.