Lizard Distributions and Reproductive Success in a Ponderosa Pine Forest

Abstract

We assessed relative abundance, demographic, and reproductive success data for two lizard species in a Northern Arizona ponderosa pine forest, a fire-dependent system unnaturally modified by fire suppression over the past century. During May to October 1997-1999, we employed up to 70 pitfall arrays to sample lizards over 6990 array-days. At each array, we described macro-vegetative cover, stand, and microhabitat characteristics. Sceloporus graciosus responded to habitat variation at all three spatial scales. Adult S. graciosus were widely distributed among cover and stand types. However, reproductive success and hatchling abundance were highest in the most open cover (meadow) and stand (savannah) types, and lowest in pure ponderosa cover and dense ponderosa stands. Adult females replaced themselves annually only in meadows, savannahs, and forest with a deciduous component. Eumeces skiltonianus adults and juveniles were least abundant in meadows, but females replaced themselves each year in meadow and ponderosa-pinyon- juniper vegetative cover and in savannahs. Hatchlings were least abundant in intermediate- and high-density ponderosa stands, whereas juveniles of both species were most abundant in areas containing a deciduous tree component. Both species were present in plots having lower percent duff groundcover than at plots containing no lizards. Increased tree densities, canopy closure, and litter accumulation influenced distributions of both lizards. Furthermore, abundance and reproduction in these lizards were generally optimized in habitat with features most similar to that present prior to fire suppression activities and in areas containing a deciduous tree component.