Monitoring a Deciduous Forest Regeneration Following a Severe Ice Storm

Leaf Area Index (LAI) has been used to estimate the carbon budget in several studies and is now mapped routinely from satellite imagery. In this study, overstory forest damage and its regeneration are assessed using in-situ LAI measurements taken from 1997 to 2007 with three optical systems (LAI-2000, TRAC, and different digital hemispherical photography camera systems) following an intense freezing rain that occurred in January 1998. The study site is composed of two deciduous stands in Larose Forest, Ontario that were damaged during an intense freezing rain event in January 1998. Time series of the variables required to estimate LAI, are assessed separately to better understand the complex architectural changes over time resulting from the impact of the ice storm. Results show that the season maximum effective plant area index (PAIe) decreased by almost 50% for both sites the summer following the ice storm (1998), but had a substantial recovery the following year (1999), and did not show any significant increase from 1998 to 2007. The 1997 to 1998 decrease was more notable for site 1, with a change of three PAIe units; while a decrease of only one PAIe unit occurred for site 2. Both site 1 and site 2 regained significant PAIe in 1999. LAI follows a similar decrease from 1997-1998 with an increase in 1999. However, LAI increased yearly by 0.06 and 0.07 units from 1999 to 2007 for site 1 and site 2, respectively. Study results also show that foliage clumping was the main driver of the LAI increase from 1999 to 2007. Site 1-the older of the two sites- regained its pre- storm LAI within six years, while the younger site 2 had not regained its original LAI nine years after the ice storm.