Common crupina monitoring report, ZPP 2011

Common Crupina Increased in Abundance on Trail Creek of the Zumwalt Prairie Preserve from 2009-2011 Heidi Schmalz and Robert V. Taylor1

Summary:  Common crupina is a noxious weed with a known population extent of ~ 51 ha on the Zumwalt Prairie Preserve (ZPP) that has been monitored for changes in abundance since 2009.  After little change between 2009 and 2010, crupina increased in abundance significantly from 2010 to 2011.  The increase in crupina occurred in the interior of the population and along the outer edge, indicating that the population is becoming denser and is spreading into surrounding areas.  The ZPP Weed Management Plan states that the crupina population on Trail Creek will be monitored for five years, with actions taken to confine it to the 2010 extent and eradicate it outside of that area. Consideration of treatment before the five year time period elapses may be warranted given the evidence for a spreading infestation.

About common crupina2 . Common crupina is a winter annual: seeds germinate in the fall, and seedlings require a period of cold winter temperatures followed by increasing day length to resume growth in the spring. . Seeds are large and heavy and fall no more than 1 m from ; bristles on the top of the seed facilitate movement into soil spaces . The seed bank is not persistent beyond the first year . Each common crupina produces a small number of seeds but seeds have high germination success . In general, common crupina has traits that favor persistence rather than rapid population growth . Crupina has been effectively reduced by hand- pulling prior to seed set, or with the following chemicals: picloram, glyphosate, dicamba, and 2,4-D (amine)

1 Corresponding author: [email protected] 2 Photos are of the (Etienne Aspord) and seed (Julia Scher, Federal Noxious Weed Disseminules of the U.S.) Purpose and Objectives of Monitoring Common crupina () is a winter annual from the Mediterranean that was first discovered in Idaho in 1968 (Stickney, 1972). In Wallowa County, crupina is a class “A” noxious weed (Wallowa County weed board) and there are a number of known populations scattered throughout the extensive riparian and canyon lands of Wallowa County (M. Porter, Wallowa Resources, pers. comm.). The Nature Conservancy staff first became aware of the existence of crupina on the Zumwalt Prairie Preserve (ZPP) in 2007. (For more detailed information about crupina and its potential detriments, see Jansen et al. 2010.)

Inventory efforts to document the extent of the crupina infestation at ZPP began in 2008. An infestation area was determined which circumscribes 51 ha of canyon hillslopes (Fig. 1). In 2009, a monitoring program was established to measure the abundance of crupina and its change over time. There are two primary objectives in this monitoring project: 1) to determine if crupina is increasing in abundance in the area it already occupies, and 2) to determine if crupina is increasing in extent beyond the boundaries established in 2009. A secondary objective is to document the abundance of several other species in the infestation area, including several native species and non-native annual grasses, to assess whether crupina is having an influence on these other species. The data and analysis derived from this project are intended to provide useful information to managers as they

Figure 1: Results from inventory of crupina along Trail Creek in 2008 and 2009 (pre-monitoring).

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make decisions about how to deal with this weed infestation.

Methods

Field Sampling There are 119 permanent3 monitoring plots within the 51-ha infestation area. Plots were stratified as either “Interior”, “Edge In” or “Edge Out” based on their relation to the known population. Plots were also stratified by topographic position (see Jansen et al. 2010 for details about how site locations were determined). The monitoring plots were visited on a yearly basis from 2009-2011, at a time when crupina was in flower and easily detected4. Prior to sampling, all observers were trained in the identification of all target species. Observers navigated to monitoring sites using a GPS and established a temporary 5 m-radius circular plot (78.54 m2). Frequency was measured by recording the presence of crupina in circular plots. We used a nested frequency method with three plot sizes (1 m, 3 m, or 5 m-radius) and recorded the smallest plot in which the plant occurred. To provide a measure of density, Counts were made within 1 m-radius plots only. At each plot (5 m- radius) we also recorded the presence/absence of Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Pseudoroegneria spicata), Sandberg’s bluegrass (Poa secunda), smooth sumac (Rhus glabra), annual brome grasses (Bromus spp.), and North grass (Ventenata dubia). In addition to abundance data collected at the monitoring plots, the locations of common crupina plants encountered outside the monitoring plots were recorded with GPS units as “incidental observations”.

Data Analysis For 2011 analyses, the data were grouped into two classes: “Interior” was a combination of the Interior and Edge In areas, while “Edge Out” remained the same as the previously defined Edge Out area. This grouping resulted in sample sizes of 79 for the Interior and 40 for Edge Out. Comparisons were made separately for each area. Topographic position was not used in data analysis.

We used frequency data to test whether the abundance of crupina changed from 2010 to 2009. No changes in abundance between 2009 and 2010 were detected in a previous analysis (Jansen et al. 2010). Specifically we tested the null hypothesis that the frequency of crupina (i.e., the fraction of 5 m-radius plots in which crupina was present) was equal between the two years. Monitoring plots were considered permanent, thus McNemar’s test was used (ProcFREQ, SAS 9.2, SAS Institute Inc.). To define a 10% chance of detecting a change when in fact a change had not occurred, we chose an alpha level of 0.1 for inferring statistical significance.

3 Permanent is a relative term here. We did not permanently mark plots, but the same UTM coordinates were used each year to locate the plots. Due to GPS error, particularly in the canyons, this could result in discrepancies of up to 10 m. However, for purposes of data analysis we chose to treat the plots as permanent plots. 4 Monitoring took place on June 11th in 2009, June 2nd and 3rd in 2010, and on June 8th and 9th in 2011.

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Density was calculated by dividing the number of plants counted within the 1 m-radius plot by the area of the plot (3.14 m2) to obtain plants per m2. Means and 90% confidence intervals of the means were obtained in JMP Software 9 (SAS Institute Inc.). No statistical tests were performed on density data.

Results From 2010 to 2011, the frequency of crupina in 5 m-radius plots increased by 18% (± 17%; 90% confidence interval) in the Edge Out, by 17% (±11%) in the Interior, and by 17% (±9.5%) across all sites (Fig. 2). These changes were significant for the Edge Out (p = 0.02), the Interior (p < 0.01) and across all sites (p < 0.01). Mean density for the Interior and Edge Out locations is shown in Figure 3. Spatial representations of frequency measured in 2009, 2010, and 2011areshown on maps in Figure 4. Incidental observations are displayed in Figure 5.

Figure 2: Frequency of common crupina in 5 m-radius plots by location and across the entire monitoring site. Error bars are 90% confidence intervals. Number of sampling plots were: Edge Out = 40; Interior = 79; All sites = 118.

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Figure 3: Mean density for Interior and Edge Out locations, by year. Error bars are 90% confidence intervals.

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Figure 5: Records of incidental observations for 2009-2011.

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The frequency data for all species within the 5 m-radius plots are summarized in Figure 6. This chart is helpful for interpreting relative frequencies—that is, the frequency of each species relative to the observations recorded for all species in a given year and area. This provides information regarding the prevalence of both native and non-native species that may be useful to future monitoring and management. For example, if the area is treated with herbicide and monitored afterward, it would be possible to compare pre- and post-treatment data regarding the abundance of target native species as well as non-native annual grasses and common crupina itself.

Figure 6: Frequency of species within 5 m-radius plots, by area and year. Each bar for each species is proportional to the total number of observations of all species within the area and year. Abbreviations are: CRVU2 = Common crupina; PSSPS = Bluebunch wheatgrass; FEID = Idaho fescue; POSE = Sandberg’s bluegrass; RHGL = smooth sumac; Bromus = all annual non-native brome species; VEDU = North Africa grass; Native Grass is a combination of PSSPS, FEID, and POSE.

Interpretations and Conclusions The key results from three years of monitoring common crupina are that 1) its frequency increased significantly from year two to year three, after no increase from year one to year two and 2) the population appears to be spreading beyond the boundaries of the original infestation, as evidenced by the increased frequency in the Edge Out area and the additional incidentals outside of the boundary. From maps of frequency over the years, the population appears to be spreading directly along Trail Creek and along the northwest edge.

Some caution is advised in interpreting abundance data for annual plants. As an annual species, crupina is likely to fluctuate in number from year to year, and whether or not the increased frequency in 2011 is the beginning of a sustained trend is impossible to know without further monitoring. Nevertheless, the increased frequency in the Edge Out area from 2010 to 2011 is indicative of spread, not just increased numbers. The Weed Management Plan for ZPP outlines the goals for managing common crupina. These goals are to 1) eradicate all

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new populations found outside of the Trail Creek infestation area and 2) confine the known infestation area to the 2010 extent (Nichols, et al 2010). Management actions may include spraying or hand pulling in the Edge Out areas only or treating the entire infestation with a helicopter spray boom. Alternatively, no action could be taken and monitoring could continue, which could provide more information about whether the increased frequency is related to yearly population fluctuation.

References Jansen, V.S., Dingeldein, J., and Taylor, R. V. 2010. Monitoring Common Crupina (Crupina vulgaris) in Tral Creek Canyon on the Zumwalt Prairie Preserve in Wallowa County, OR. The Nature Conservancy. Available online at: http://conserveonline.org/workspaces/ZumwaltPrairieWorkspace/documents/monitoring-of-common-crupina- crupina-vulgaris-in/view.html

Nichols, L.J., Jansen, V.J., and Fields, Jeff. 2010. Weed Management Plan, Zumwalt Prairie and Clear Lake Ridge Preserves. The Nature Conservancy internal document.

Stickney, P. F. 1972. Crupina vulgaris (Compositae: ), new to Idaho and . Madron˜o 21:402.

Wallowa County Weed Board. 2009. Class A Listed Noxious Weeds of Wallowa County. Enterprise OR: Wallowa County Weed Board

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