Abstract
The data and analyses presented here were collected at the Zumwalt Prairie Preserve (ZPP), northeastern Oregon. Vegetation composition was measured within 124 (1-ha) plots using the line point intercept method [1,2]. These data include vascular plant species abundance matrices at two different time periods, seven years apart (2008/2009 & 2015/2016); boxplots of species abundance (cover and frequency) change over time; Non-parametric Multiplicative Regression (NPMR) estimated abundance of Ventenata dubia, an invading non-native annual grass, in geographic and ordination (Non-metric Multidimensional Scaling ordination; NMS) space over time.