PARENT SESSION
Poster Session # 11: Disturbance Ecology.

Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Effects of fire intensity on understory vegetation diversity in the Black Hills of South Dakota.

Derr, Katharyn^*,, Matzner, Steven,

ABSTRACT- Fire has become an increasingly important issue in western states because of the frequency and severity of many recent wildfires. Years of fire suppression policy have resulted in higher fuel loads that cause fires to burn more intensely. This paper presents a study on the effects of different fire intensities on the understory vegetation in a Pinus ponderosa community at the Jasper Burn Area in the Black Hills of South Dakota. It was hypothesized that high intensity fires would be more damaging to forest understory recovery, while low intensity fires might lead to increased diversity by stimulating the growth of more fire tolerant native species. It was also hypothesized that the low intensity burn sites would have fewer invasive species compared to the high intensity burn or unburned sites. The results however did not conform to our original hypotheses. Species richness and diversity were not significantly different between high and low intensity burn sites. In fact, the unburned sites had significantly higher species richness and diversity compared to either the low or high intensity burns. Analysis of individual species changes revealed that fire of any intensity resulted in the loss of fire intolerant species, but that fire did not appear to be stimulating growth of fire tolerant native species. The absence of an increase in fire tolerant natives may be due to a lack of seed source or individuals to resprout. Recovery of natives in this system may occur more slowly than originally thought and may require additional burn events before recovery is complete.

Key words: Understory, Pinus ponderosa, Fire, Diversity