An assessment of invasive plant species in northern U.S. forests

Abstract

Invasive plant species (IPS)¹ have been monitored on select Phase 2 (P2) FIA plots since 2005 in the Midwest and since 2007 in the northeastern part of the NRS region. In 2005 and 2006, IPS data were collected year-round on 100 percent of the plots. Starting in 2007, the sampling intensity changed to collecting IPS data on 20 percent of plots with the monitoring window running from May through September. Since 2012, IPS data are collected on the Phase 2 Plus (P2+) sample. These plots are a 12.5 percent subsample of the Phase 2 plots, measured from May through September, and only occur on forest land.2 In this report, the 2014 and 2019 inventory data are presented to examine how IPS have changed over time. NRS FIA crews monitored 6,361 forested plots for invasive plants during the 2014 inventory and 4,244 in the 2019 inventory. Along with the standard forest variables collected during P2 measurement (e.g., tree diameter, height), these plots have various other attributes collected including the occurrence and coverage of IPS, vegetation structure, and down woody debris.

Citation

Kurtz, Cassandra M. 2023. An assessment of invasive plant species in northern U.S. forests. Res. Note NRS-311. Madison, WI: U.S. Department of Agriculture, Forest Service, Northern Research Station. 5 p. https://doi. org/10.2737/NRS-RN-311.