[BoulderCouncilHotline] Re: Questions on Prairie Dogs

[Burke, Dan]

Good morning Council.

This email is a follow up to the Hotline Post dated 4/26/19 when staff responded to questions 1-32 received from Council members Lisa Morzel, Cynthia Carlisle and Mary Young regarding prairie dogs. For the 4/26/19 Hotline post staff were not able to respond right away to question #33-#46 below; responses to questions #33-#41 are now provided below.  The initials of the council member asking the original question are included at the end of each question.  Attached is a Word Document of these responses.  Thank you and enjoy this beautiful weekend day.

Dan Burke, OSMP Interim Director

33.	Would it be possible to restore irrigated lands to a state similar to that in the Southern Grasslands and how long would that take? (MY).  

Many of these lands were purchased together with irrigation water rights and have a long history of agricultural irrigation.  A comprehensive analysis would need to be performed to understand the potential impacts of this management strategy to the preservation and stewardship of these water rights assets.  OSMP’s Charter includes the preservation of agricultural land and agricultural uses, as well as the preservation of water resources in their traditional state.  Any conversion of agricultural lands to natural lands would need to consider how this would impact the department’s ability to meet this charter purpose.  Restoration activities could be developed on a site specific basis, but would generally include a combination of soil preparation and amendment, seeding and invasive species control activities.  

It generally takes two to five years for a native grass seeding to become successfully established, depending on precipitation, soil productivity, landscape context and other factors.  Hayfields or irrigated pastures may be capable of becoming re-established to meaningful agricultural productivity in one growing season.  Restoration and reclamation costs vary depending on the amount of soil preparation or amendment that is necessary and the diversity of the seed mix.  Reclamation that included only land leveling and seeding would cost approximately $90-$100 per acre.  More extensive reclamation that included key line plowing, tillage, compost application and seeding would cost approximately up to $500 per acre.  OSMP has former agricultural land that was seeded to native grasses 20-30 years ago.  These grasslands still do not exhibit the resiliency of undisturbed native grasslands.  Staff can also identify tilled areas on the landscape by its vegetation composition even though it has not been tilled since the 1960’s. These costs represent estimates for restoration however, this does not account for the unknown costs and implications that need further analysis as previously mentioned.

Restoring grasslands to conditions similar to those in untilled (never plowed) portions of Southern Grasslands is not possible in the timeframe we have been able to observe restoration progression (30 years).  This type of recovery would likely take substantially longer, or may not be possible due to fundamental differences in soil structure and health on tilled and untilled lands.

34.	How have drought/flood conditions affected our grass lands and Ag lands over the past 10-15 years? (LM).  See below

35.	What are those changes resulting from drought/flood? (LM).  See below

36.	How are affects of drought/flood monitored? (LM). 

Answer to #34, 35, 36: Drought is a key ecological process that shapes Boulder’s grassland plant communities. Over the last 30 years, Boulder has experienced some dramatic cycles in climate: In broad terms, the 1990s were wet and cool, the 2000s were droughty, and the 2010s were highly variable, with one intense drought in 2012, and of course the flood of 2013. For Boulder, the 2012 drought was its third driest spring on record, and its least snowy spring ever. Major droughts like these can lead to the browning of grasslands, noticeable to even the most casual observer, which raise the risk of wildfire and undoubtedly impact plant communities and their dependent wildlife and insects. 

A graduate student is currently analyzing decades worth of grassland plant community data (1991-2018) collected by staff from the Colorado Tallgrass Prairie State Natural Area, an OSMP area just west of the South Boulder Creek West Trailhead. Her work is beginning to shed new light on how drought affects plant communities. Cool season, C3 grasses appear to be particularly sensitive to droughts, while warm season, C4 grasses are stable. Native wildflowers (i.e., forbs) infill in droughty years and increase biological diversity, but droughts also offer an opportunity for some non-native species to invade. Despite these changes, the overall health of these grasslands remains largely intact, with no major declines of native species diversity. 

In addition to this study, staff have been monitoring grassland vegetation health on a much larger spatial scale (i.e., systemwide) since 2009, guided by the Grassland Ecosystem Management Plan. In-progress data analyses show remarkable stability in attributes like native species richness and native species cover, despite highly variable climate conditions.

Combined, these two monitoring projects suggest that intact native grassland communities are very drought tolerant and resilient to environmental change. However, with the forecasted increase in aridity for the front range, including a high likelihood of more frequent droughts, the long-term fate of grasslands is largely an open question. In response to this, staff is sponsoring a field experiment, as part of a nationwide NSF-funded DroughtNet program, to test grassland response to experimental water manipulations that mimic future levels of drought.

In response to changing conditions caused by drought, staff’s main management strategy is to use rotational, deferred (rest rotation) cattle grazing and seasonal stocking to lower the impacts of drought.

In the agricultural context, drought can reduce water storage, water availability and water quality for agricultural use. In turn, agricultural yields will necessarily be lower in drought years. Flood, on the other hand, can exceed the water holding capacities of agricultural soils, causing loss of yields and the soil itself. The Agricultural Resources Management Plan (Ag Plan) has the following strategy to mitigate the effects of predicted drought and severe rainfall events from climate change: Establish objectives for soil health on OSMP agricultural lands that include consideration of water holding capacities and water infiltration into soils during rainfall event. Staff are in the early planning phase for this strategy.

37.	Are we overgrazing- how is that measured and monitored? (LM). 

As part of the systemwide grassland monitoring program started in 2009 mentioned above, staff have been monitoring “bare ground,” which is used as an indicator of overgrazing. When grazing intensity is too high, little vegetation is left of the landscape, and thus the amount of bare ground is high. Of course, other factors like available soil moisture and higher levels of productivity also influence the amount of bare ground.

Over the years, bare ground has been consistently ranked as “fair,” “good,” or “very good.” Both good and very good are within the acceptable range of variation; these ratings apply to our mesic big bluestem grassland type and our xeric tallgrass prairie grassland type. The fair rating is outside the acceptable range of variation; this rating applies exclusively to our mixed grass prairie mosaic grassland type. In these grasslands, it is likely that grazing intensities by livestock and wildlife are associated with higher than acceptable levels of bare ground, at least in some areas and some (dry) years.

The Ag Plan has the following two strategies related to improving our use of prescriptive grazing as an ecological management tool that has sensitivities to climate variability: (1) Formalize a grazing de-stocking protocol to allow strategic rest in times of drought, and (2) Incorporate climate into a Rangeland Condition Assessment protocol and monitoring. Staff are in the early planning phase for both strategies.

38.	At stop #2, we looked out at a relocation site where temporary tubing was laid down as temporary shelter for prairie dogs. This relocation occurred at that particular site because the soil had, in the past, seen disturbance. I understood that the same sorts of temporary shelters would be used in the Southern Grasslands. What measures would be taken, after soil disturbance, to minimize the incursion of invasive non-native plant species onto the Southern Grasslands? (MY). 

Staff would use a set of best management practices to prevent, minimize and reverse any ground disturbance (e.g, access routes for excavation equipment and other relocation activities; nest box excavation). Staff would select sites where resources are already impacted (e.g., weed patches) or disturbed, keep the footprint of any new ground disturbance as small as possible, reseed disturbed areas where necessary and conduct follow-up monitoring and treatments to locate and remove weeds.

39.	Brett talked about the experimental treatments to improve soil health and Carbon sequestration on degraded lands, its success thus far, and that this effort is not now budgeted. How much will the city need to budget over what period of time to achieve the desired improvements?  What fraction of the 1,000 acres do you expect to treat this way vs. the prairie dog relocation, seeding and irrigation treatment that Andy described? (CC).  
A preliminary assessment of the costs of land degradation is being compiled as part of the 2019 survey of degraded lands and treatment options.  OSMP is experimenting with developing land regeneration contracts in which contractors will be paid for regeneration services and it is expected that approximately 60 acres of the Bennett property will be managed using this contract.  There is insufficient experience to-date to develop a clear expectation for these costs but we would anticipate full regeneration of currently degraded sites to cost anywhere from $50-$500/acre depending on site conditions.  This is in many cases in addition to the costs of materials such as compost.  The application of just a ¼” thickness of compost—one of the treatments developed by the Marin Carbon Farming project currently being tested for land regeneration—would cost $350-$400/acre (not counting the cost of application).  The compost alone would cost over $400,000 if all 1,000 acres of prairie dog occupied irrigated lands already identified in the OSMP inventory were treated with compost.  This does not cover the other costs associated with land recovery noted above.  More information on land recovery costs will be developed through the assessments conducted this year.  OSMP has requested $182,000 in its 2020 CIP budget to manage or reclaim irrigated agricultural lands in areas where prairie dog colonies have been relocated or prairie dog populations have changed.   
Because this program is very early in its implementation, full scale application has not been fully scoped, and where these techniques vs. traditional prairie dog management and restoration post plague has not been determined.  
40.	What will be the approximate costs of restoring the 1000 acres of degraded lands using standard/traditional means? And how long will it take to bring them back to being productive? (CC).  
There is insufficient experience to-date to develop a clear expectation for these costs but we would anticipate full regeneration of currently degraded sites to cost anywhere from $50-$500/acre depending on the conditions. So for 1000 acres, costs will likely be $50,000- $500,000 dollars.  These estimates do not include the cost of prairie dog removal, or barriers or other actions to exclude prairie dogs in the future.  The timeframe would likely be 1-3 years for each property depending on weather and resource availability. 

41.	I understand that the native prairies in the Southern Grasslands naturally sequester Carbon – can we have an idea of how much Carbon sequestration they are responsible for in comparison to irrigated ag pastures and OSMP forests? (CC). 
Native ecosystems and appropriately managed agricultural systems all have the ability to sequester carbon.  OSMP grassland or forest systems have not been studied, but we do know that grasslands generally sequester less carbon than forest lands and that soil moisture is an important driver of carbon sequestration.  Because of this, irrigated agricultural lands have the potential to sequester more carbon than dry grasslands in our area.
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The following questions were included in the original hotline postings.  However, determining answers to these questions would require substantial work from staff to research lethal control and analyze what would be required for its use on city lands.  Collecting this information is not feasible prior to the City Council meeting. Staff will undertake this information gathering in the event that City Council gives direction to pursue additional evaluation of lethal control.

42.	How many years of relocation and lethal control would it take to reach the goal of 26% occupancy in the north if a plague event did not occur? (CC). 

43.	How many prairie dogs could be removed using the kinds of removal strategies that the County is using and transfer the prairie dogs to the Raptor Center or the Black-footed ferret Center in Ft Collins and at what cost? (i.e., staff and equipment/materials costs) (CC).  

44.	It was mentioned at stop #3, that the National Black Footed Ferret Conservation Center in Carr, CO cannot meet its demand for prairie dogs as a food source for its captive and breeding ferrets. The county is currently contributing prairie dogs to the center. The process, it was said, requires a period of prairie dog quarantine (to ensure absence of sylvatic plague) prior to the center accepting them. (MY).
a.	What is the quarantine period?
b.	What is the cost/prairie dog for this process?
c.	If council were to direct this approach, would partnering with the county be an option? 


45.	Describe the process involved in donating prairie dogs to either the raptor or BFF recovery programs. (MY). 

46.	Finally, while I have no interest in lethal control of pd’s, I am curious what the cost would be for lethal control, staffing, and restoring those particular Ag lands most affected by pd’s back to a “productive “ state and how long would that take?    I again am assuming cattle could not graze during the restoration so the current cow population on those lands would need to move. Is that correct? (LM).


Dan Burke
Interim Director
Open Space and Mountain Parks
						

303-817-3143					
burked at bouldercolorado.gov

2520 55th Street| Boulder, CO 80301
Bouldercolorado.gov



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