Vernal Pool Proposal

Avery, Alec, Kiely

Here is our proposal for vernal pools !

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Grazing Ameliorates Competitive Stress on Native Plants in Hog Wallows

by

Alec Chiono, Avery Kruger and Kiely Doherty

Introduction:

Once prevalent across the Central Valley, vernal pools provide unique habitat for many endemic species, including numerous plants. Unfortunately, vernal pools are far less common, and invasive plants are a threat to the native populations. Grazing has been implemented as a means to reduce the impact of invasive plants in vernal pools. It has been shown that grazing reduces invasive cover and increases native cover (Marty 2005). However, the mechanisms that lead to increases in native plants have not been fully explored. It is thought that grazing can favor native plants because the grazers preferentially feed on invasive grasses or that they alter the hydrology of pools in favor of the natives (Boucher, personal conversation, 2015). We propose to study the effects that grazing has on competition between native and invasives. Jepson Prairie Preserve offers a great place to explore this topic, as previous studies have shown that grazing by sheep has helped support native plant populations (Swiecki and Bernhardt 2007). Not only can we gain insight into the competitive relationships between natives and invasives, but by quantifying the effects of grazing on competition we can better understand grazers as a management tool.

 

Hypothesis:

Invasive plants compete with native plants, and so grazing invasive plants increases the rate of growth of native plant biomass by reducing invasive plants’ competitive ability.

 

Methods:

30 20cm x 20cm sections of turf to depths of 10 cm will be taken from Jepson Prairie Preserve. Three treatments of 10 replicates will be established. In the first, invasive plants will be selectively weeded out. In the second and third, an equivalent biomass of plants will be haphazardly weeded. Turfs will be placed in a greenhouse and watered weekly. The native plant treatment and one haphazard treatment will be allowed to grow normally, while the final treatment will be artificially grazed weekly by cutting invasive plants to a height of 3cm. We will randomly choose and mark 5 native and 5 nonnative plants in each turf. The height and leaf width will be measured on a weekly basis for each marked plant, which will be identified to genus or species level if possible. After 5 weeks, plants on each turf will be separated by native or invasive status, dried and massed.

 

Expected Results:

We expect that final native plant biomass would be largest in the native plant treatment, and native biomass in the grazed treatment would be larger than the ungrazed treatment. In plots of the weekly measurements, we expect to see that growth rate would decrease as invasive plant size increases.

 Screen Shot 2015-02-01 at 9.08.28 PM

Fig. 1. Potential plot of weekly change in height of native plants vs average height of invasive plants present.

Screen Shot 2015-02-01 at 9.08.36 PM

Fig. 2. Potential plot of end biomass for each treatment. Real plot would include a second column for each treatment for invasive biomass.

 

Cost Estimate

$3.32 per trip per car (x3)=  $10 in fuel costs per trip for one trip

Greenhouse rental fee:

  • Require 12.9 square feet, round to 13 sq. ft.
  • Yearly Fee Estimate (Kate) $10 to 12/ sq. ft. = $130 to 156
  • Monthly Fee Estimate $3.25 to $4/ sq. ft. = $43.25 to 52

Potting Materials (possibly included)

Total Cost: minimum $53, maximum $166 depending on greenhouse fees

Timeline

Within the next week (week 1):

Rent Greenhouse

Coordinate with Virginia to gather samples (turfs)

  • Need to replicate the same native and invasive species throughout the samples

Plant the treatments and water

Weeks 2-5:

Artificially graze the indicated plots

Start taking data points

Visit Jepson Prairie Preserve for observational component

  • Presence/Absence

Measure total biomass at the end of the data collecting period

Compile and Analyze data

Works Cited

Marty, J. T. 2005. Effects of Cattle Grazing on Diversity in Ephemeral Wetlands. Conservation Biology 19:1626–1632.

Swiecki, T., and E. Bernhardt. 2008. Effects of grazing on upland vegetation at Jepson Prairie Preserve: Third year (2007) results and final report.

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Cost Estimate

$3.32 per trip per car (x3)=  $10 in fuel costs per trip for 10 trips

Greenhouse rental fee:

  • Require 12.9 square feet, round to 13 sq. ft.
  • Yearly Fee Estimate  $30 sq. ft. = $390

Potting Materials (possibly included)

Total Cost: minimum $100

 

Timeline

Within the next week (week 1):

Rent Greenhouse (contact: Doug Walker   dewalker@ucdavis.edu)

Read up on vernal pools and the threats of introduced species (drop box it up!)

Research effects of grazers aside from purely biomass removal (compaction, saliva induced responses, etc.)

Coordinate with Virginia to gather samples (turfs) set up plots along transect of inundation gradients

Plant the treatments and water

 

Weeks 2-5:

take measurements

Artificially graze the indicated plots

Start taking data points

Visit Jepson Prairie Preserve for observational component

  • Presence/Absence

Measure total biomass at the end of the data collecting period

Compile and Analyze data

 

Edit:

We are proposing to move this project to the field, as we agree that the field would offer the best environment to test these ideas. In order to make this more feasible, all three of us would be willing to drive every time we go out. We are keeping the same treatments, but adding a hydrological component. To achieve this, we will replicate treatments along inundation gradients. The inundation gradient would be determined by measuring water depth if inundated and soil moisture in plots that are not inundated. We would expect that grazing would have a stronger effect in weakly inundated areas. Evapotranspiration rates could be measured additionally to look at quantitative water use on an individual basis in parallel to the rest of our experiment. We would like to make artificial grazing as realistic as possible, but have not yet found examples of artificial grazing techniques. Depending on how often the class is willing to go to the field site, we can reduce frequency of grazing and plant measurement.

 

Clarification: Haphazard weeding is used to isolated purely the effects of weeding from the effects of invasives being present or not. Haphazard weeding is accomplished by removing the same number of individuals from each plot.

 

More Citations:

Boucher, Virginia. 2015. Personal conversation.

Box, P. O., and R. Bluff. 1996. Managing the Sacramento Valley Vernal Pool Landscape to Sustain the Native Flora. Ecosystems:236–240.

Robins, J. D., and J. E. Vollmar. 2002. Livestock Grazing and Vernal Pools. Wildlife and Rare Plant Ecology of Eastern Merced County’s Vernal Pool Grasslands:401–430.

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