Phytosphere Research

Jepson Prairie Preserve Vegetation Monitoring Transects:  Analysis of data from 2001 through 2011

June 2012

T. J. Swiecki and E. A. Bernhardt
Phytosphere Research, Vacaville CA

Download the full report (Adobe Acrobat PDF - 2.9 MB)

Additional key words: weed management, vernal pools, GIS, GPS, spatial analysis, repeated measures


In 2001, we developed a transect-based monitoring system for assessing changes in exotic and native plant cover at Jepson Prairie Preserve (see Exotic and Native Plant Monitoring at Jepson Prairie Preserve, 2001).  The monitoring system was designed to detect significant changes in cover and distribution of selected species across the entire preserve.  The monitoring system is based on permanent transects that are assessed annually in the spring, near the time of peak bloom of many native spring annuals.  Transects pass through every pasture unit at the preserve.  The basic data unit is a 0.1 ha strip transect, 50 m long by 20 m wide.

We performed an analysis of the data collected using this system for the 11 years from 2001 through 2011.  The primary objectives of our analysis were to:
- identify directional trends indicating long-term increase or decrease in the cover of any monitored species:
- identify significant patterns of change over time that may not have resulted in net changes in cover from the beginning to the end of the observation interval;
- determine whether environmental, management, or other factors are associated with observed changes over time and space.
In addition, we assessed whether reducing either the frequency of data collection or number of transect segments would affect our ability to discern trends and assess the influence of predictive factors.

This report decribes the results of these analyses and provides recommendations for continued monitoring of the preserve.

This project was funded by the Solano Land Trust.