Climate Change and Prairie Plant Range Distributions

The predicted effects of climate change have serious implications for remaining upland prairie in the Pacific Northwest and globally.  Pacific Northwest upland prairie is an imperiled ecosystem because of major losses to agriculture, urbanization, woody encroachment, and invasion. Prairie species are often range-limited and thrive only in certain environments.  To manipulate the predicted environmental changes in the next century and predict the effects of a changed climate on upland prairie, an experiment was designed in which sites were selected along a natural climate gradient from southwestern Oregon to central Washington.  Five replicates of four treatments were implemented at each site: increased precipitation by 25% above background rates, increased heat by 3°C above ambient, increased precipitation and heat, and controls.  A matrix of native prairie species was broadcast into the plots and 14 range-limited species were planted in specific locations.  The range-limited species are monitored closely to record presence, growth, survival, fitness, and phenology. 

Five range-limited perennial species were selected to collect various measures of growth for allometric analysis.  Logical allometric measures were chosen for each species dependent on usual growth form prior to data collection. Because perennials were measured, some individuals were left in the plots while others were harvested in order to establish allometric relationships.  Biomass was correlated with determined best fit measurements, and a model was generated to predict biomass of unharvested plants.  This allows us to predict biomass of perennials at different stages without harvesting them as well as to correlate biomass with vigor and fitness.