Comparing vegetation monitoring methods in shrublands: how valuable is Grant's method in shrub communities?

Faced with managing extensive rangelands, land managers need reliable monitoring methods. Grant and others (2004) proposed a monitoring method that uses a floristic classification of dominant vegetation and assesses species frequency. The method was developed in native grass prairies with limited woody vegetation and is designed to provide more efficient repetitive monitoring. Our objective for this study was to determine if Grant’s method is useful in shrubland systems for a newly implemented baseline inventory and monitoring program. We conducted a study to compare Grant’s method and its efficacy to more commonly used line-point intercept in grass and shrub alliances at Brown’s Park National Wildlife Refuge, Colorado. In the summer of 2007 we conducted baseline inventory of vegetation characteristics on 39 permanent bottomland plots in six pre-determined grass and shrub vegetation alliances on the refuge. Within each plot, we monitored vegetation with line-point intercept and Grant’s method on three 50 m line transects. We compare data collected using these methods from a grassland (smooth brome dominated) and a shrubland (greasewood dominated) alliance. Results of this study indicate that data collected using Grant’s method is more variable than line-point intercept data in shrub systems. Bare ground was detected less using Grant’s than line-point intercept; however, Grant’s detected more herbaceous and invasive species overall than did the line-point intercept method. A complementary use of the methods for long-term monitoring is recommended that accommodates tradeoffs between incorporating detail versus efficiency of data collection efforts.