In temperate forests, small-scale disturbances resulting in single or multiple tree fall patches play an important role in driving stand dynamics. Many factors contribute to patch regime heterogeneity within and among forest stands, including wind and storms fire, site erosion and landslide, stand age, and stand composition. While there is evidence suggesting that topography can also affect patch formation, most studies have examined patches in steep terrain rather than in relatively level terrain such as temperate forests. This study examined the treefall patch regime among three microtopographical classes: ridge, slope, and bowl in a mixed hardwood forest in the Mazandaran of north Iran. The first hypothesis that the patch regime does not vary among microtopographical positions was tested. Using point sampling, microtopographic variation was estimated throughout the site. Line intersect sampling was used to select patches for measurement of patch frequency, area, fraction (percent cover) and abundance (density) within the study area. Patch area, frequency, fraction and abundance differed significantly among topoclasses. Ridges contained the highest patch area, frequency, fraction and highest abundance compared to slopes and bowls. Based on these findings, the first hypothesis was rejected and we concluded that microtopography affects at least some aspects of the patch regime in this mixed hardwood forest.
