White Ash Decline Hazard Assessment and Management Strategies in Massachusetts Stands

Abstract

Abstract White ash decline is characterized by diminished growth rates and vigor, and premature mortality. Reducing its impact should be a primary management objective in stands with a white ash component. Two methods to identify Massachusetts sites with high hazard of decline were developed using continuous forest inventory (CFI) data. Method 1 uses a vegetation-based estimate of relative soil moisture availability and landscape position data to calculate a decline hazard index (DHI) for the site. A DHI > 1.0 indicates a high hazard site. Four of 18 CFI plots with ≥25 % white ash BA had DHI > 1.0. Field observations in 1991 confirmed ash decline on three of the four plots. Trees on the remaining 14 plots were healthy. Method 2 uses site index (SI) and rooting restriction type (from soil maps) to assign sites to one of three classes, and does not require the collection of field data. Class 1 (SI ≥70, deep soils or dense substratum) and class 2 (SI ≤65, all soil types; SI 70, soils with bedrock at 20-40 in.) sites have a low decline hazard. Class 3 (SI 70-75, soils with bedrock at ≤20 in.) sites have a high hazard. Method 2 was tested on a data set of 74 CFI plots with ≥10% ash BA. Differences among site classes in the numbers of plots with decline were significant (P = 0.0016), with decline on 6% of plots in class 1 and 11% in class 2, compared with 42% of plots in class 3. Method 1 should be more accurate since vegetation data are collected onsite, and it integrates the many variables influencing soil moisture available to plants. Method 2 is quicker and easier to apply. Its accuracy could be improved by collecting soil data onsite. North. J. Appl. For. 14(1):10-15.