Understory vegetation and site condition data from the "Nonnative Invasive Plants" study at the Penobscot Experimental Forest

This data publication contains understory plant density and cover class, substrate condition, microtopography, soil drainage, and canopy openness collected in 2006-2007 for 654 milacre plots (milplots) on 327 plots in 24 forest stands representing 10 silvicultural treatments (including an unharvested reference) and an old field on the Penobscot Experimental Forest (PEF) in central Maine, USA. These data were collected to obtain a more complete understanding of the extent of invasive species in a long-term PEF silvicultural experiment, as well as the relationships between treatment, site, and characteristics of the understory plant community.The objectives of this study were to determine the extent of nonnative invasive plant populations in the Compartment Management Study (CMS) and an old field in the PEF, and to relate characteristics of the understory plant community generally, and invasive plant abundance and distribution specifically, to management history and environmental factors.For data relating to the overstory composition of the permanent sample plots (PSPs) in the CMS (the long-term research area in which most of these data were collected), please refer to Kenefic et al. (2015, https://doi.org/10.2737/RDS-2012-0008-2). We strongly recommend that users read the accompanying documentation provided with the full data publication download before proceeding with data summary or analysis. Data were published on 05/14/2019. Minor metadata updates were made on 05/18/2021.