Sedgwick Reserve

30 Apr, 05 PM - 30 Jun, 05 PM

We are combining manipulative experiments and population growth models to understand the contribution of niche and fitness differences to the coexistence of serpentine annual plants in California. Our approach is based on the observation that all niche differences result in negative frequency-dependent population growth. Thus, we wanted to determine the net contribution of all niche differences to coexistence (without identifying individual niche mechanisms) by quantifying frequency-dependent population growth rates. We also proposed to use well-studied annual plant models to quantify fitness differences in the absence of niche differences, with which we can project the rapidity of competitive exclusion in a world without niches. Finally, we wanted to empirically test the predictions of these annual plant models by forcing focal species to experience ?niche absent? population growth rates in experimental mesocosms. In the last two years, we?ve established the experiment (initiating 130 experimental communities with field-collected seeds from ten species) and completed two years of data collection and analysis. Field work involved marking and identifying germinants, collecting and weighing seeds as they ripen, burying mesh bags of seeds to quantify seed survival, and seed viability testing. Measuring these demographic quantities in plots where the frequency of each species ranges from rare (1%) to common (100%) allowed us to determine whether population growth rates are frequency-dependent (as would be expected when niches are stabilizing community diversity). We also parameterized annual plant population models with these field demographic estimates to predict ?fitness differences?; population growth rates in the absence of niche differences. Finally, we imposed these population growth rates on experimental communities and compared their diversity dynamics (as relative abundance of each species in seed production) to control plots to determine how the stabilizing demographic effects of niches contributes to community structure. The experimental manipulations are intended to continue for an additional 2-3 years (possibly more). Activities in the following year will be identical to that in the previous year(s): sowing seeds, monitoring germination and seed production, collecting seeds from experimental plots, and quantifying environmental variables in the plots. All research is occurring on the northern part of Sedgwick reserve, between serpentine hummocks (latitude 34.738798?, longitude -120.026212?, 391 m elevation). In 2009-2010 we are continuing to collect data from this experiment as described in the project's application. Please note that the experiment is time intensive, and listing individual dates/times that we will be on the reserve is difficult. Previous experience indicates that at least 2 of the research participants listed below will be present on the reserve 2-5 days a week year around. The research assistants are most likely to be present.

Visit #23776 @Sedgwick Reserve

Approved

Under Project # 5611 | Research

California annual serpentine communities

faculty - University of Washington

Reservation Members(s)

Group of 3 Graduate Student Apr 30 - Jun 30, 2011 (62 days)
Janneke Hillerislambers Apr 30 - Jun 30, 2011 (62 days)
Group of 2 Research Assistant (non-student/faculty/postdoc) Apr 30 - Jun 30, 2011 (62 days)
Group of 2 Faculty Apr 30 - Jun 30, 2011 (62 days)

Reserve Resources(s) | Create Invoice

Day Use Only 8 Apr 30 - Jun 30, 2011