Comments by Friends of Boulder Open Space
March 30, 2009
More than half of our city open space lands are grass-dominated ecosystems, remnants of landscapes that once covered much larger areas along the Front Range of the Rockies. They are important in part because they are protected. For the first time, OSMP has taken a close look at their composition and their condition. The draft report reveals the remarkable diversity of life they support.
The purpose of the report is to “provide a framework of on-the-ground management … priorities to conserve the ecological values ….” Development of this plan follows a six-year process (1999-2005) that produced the Visitor Master Plan and a three-year period (2005-2008) in which two “trail study area” plans were completed. Only now are we developing an understanding of the lands and resources that is essential for their long-term management and that should have preceded any decisions about their long-term uses.
Although driven in part by concern about prairie dog management, the grasslands plan is fundamentally a conservation plan. It is addressed first and foremost to the physical and natural environment of the lands, and its primary objective is to determine their important ecological values and actions needed to maintain and enhance these values. The analysis provides a much needed baseline for these lands and begins the process of putting in place objectives and initiatives to guide future management.
Using a scale that ranges from very good, good, fair, to poor, the plan concludes the overall condition of the grasslands to be fair. The plan divides the grasslands area into seven “targets” for analysis: mixedgrass prairie mosaic, xeric tallgrass prairie, agriculture, black-tailed prairie dogs and associates, wetlands, creeks and riparian areas, and White Rocks. For each target the plan identifies existing condition and objectives for improving conditions.
The report assesses threats to its conservation targets and determines an overall threat ranking of “very high.” Threats identified as “critical” are incompatible trails/recreation, surrounding land uses, incompatible practices by dog guardians, and incompatible water management/use as well as invasive plant species, non-native leopard frog predators, and inappropriate fire management. The analysis also identifies what are termed “best opportunity” areas for achieving conservation objectives. For example, the largest available blocks of habitat types on open space lands provide the best opportunities for conservation of the associated ecosystems.
Finally the report outlines a list of conservation objectives that represent staff determination of priorities for the grassland planning area. These include objectives directed at prairie dog management, bald eagles, weeds, vegetation composition and structure, butterflies, avian habitat, aquatic and riparian resources, leopard frogs, and agriculture.
The grasslands within the OSMP system are protected because they exist on lands purchased or protected by the city to shape its development boundaries and to provide a buffer from neighboring development. In some cases these lands contain “terrain, geologic formations, flora, or fauna that is unusual, spectacular, historically important, scientifically valuable, or unique, or that represent outstanding rare examples of native species; ….” Much of the land contains areas of agricultural use, including grazing and irrigated meadows for hay. These lands also provide important opportunities for passive recreation.
While it has taken more than 40 years, acquisition of these lands may turn out to have been the easy part. Now we are faced with the challenge of determining as a community how we want to manage them. The Grassland Ecosystem Management Plan is the first step in taking a comprehensive look at our grasslands, determining what we have, assessing their condition, and beginning the work of deciding what our long-term objectives for these lands are.
In our view, the initial task is to determine what habitat these lands provide and the quality of that habitat. We believe our first priority is to protect and enhance this habitat.
What the Plan Tells Us
Of the three primary grassland types, the most common is the mixed prairie mosaic. Such grassland types are found widely in the Great Plains and the Intermontane West. Nevertheless, there are important reasons to manage these lands for their habitat values. Particularly in the large blocks, these lands provide important nesting habitat for many species of grasslands-obligate birds. Among the many vertebrate species identified on these lands are such “uncommon” species as the short-horned lizard, olive-backed pocket mouse, and several rare butterfly species. In addition to the value of periodic fire to renew essential ecological processes, the single most critical management requirement is to maintain existing unfragmented habitat blocks. Unique areas such as the shale barrens located on lands in the northern part of the system require special protection.
Prairie dogs are found most commonly within these mixed prairie mosaic lands. Boulder’s protection of lands with these characteristics has provided protection as well for prairie dogs. Under pre-development conditions, prairie dogs established colonies in such areas while living off the associated vegetation. As food sources diminished, prairie dogs would move to different lands. With rest and moisture the previously colonized lands reestablished their vegetation. With extensive human habitation and use of former prairie lands in Boulder County, prairie dogs have few places to go. Only periodic plague events seem to reduce prairie dog populations, allowing colonized lands some time to recover.
OSMP grasslands also include a relatively large amount of xeric tallgrass prairie, characterized by the presence of big bluestem. This prairie type is predominantly located along the foothills at elevations above the town of Boulder. Xeric tallgrass prairie is much less common in Colorado and globally than the mixedgrass prairie mosaic, and its presence on city open space warrants special management attention. Of special importance is their value as habitat for rare butterflies, including Ottoe skipper, Arogos skipper, crossline skipper, and regal fritillary. Large, unfragmented blocks provide important nesting habitat for a number of grassland birds. Elk graze these grasslands seasonally.
The third grassland type found on OSMP lands is the mesic bluestem prairie. The largest remnants of this type in Colorado are found here in Boulder. Lands containing mesic bluestem prairie are located in about 20 patches from about 5 to 65 acres. One such area was designated the Colorado Tallgrass Prairie State Natural Area in 1984. This prairie type also provides important habitat for rare butterflies, nesting habitat for grassland birds, including bobolinks, and “robust” rodent populations that attract a large number of raptor types. These small but unique areas are clearly deserving of special management attention.
While riparian areas and wetlands are also discussed in this plan we would prefer to see these critical water-dependent habitats treated separately and so defer any additional comments at this point. Separate treatment would allow consideration of ways to improve the in-channel habitat of our perennial and intermittent streams.
What We Would Like to See
1. Respecting prairie dogs
We are fortunate in Boulder County to have protected prairie landscapes in which prairie dogs can still live and thrive. They are an important part of the prairie ecosystem that must be sustained. Yet we see prairie dogs in the larger context of the landscape. Our primary concern is ecosystem health, including all the component parts.
Thus we support staff conclusions that there are carrying capacity considerations that must be taken into account when managing OSMP grasslands for prairie dogs. We cannot independently evaluate recommendations for minimum and maximum occupied acreage and their distribution, but we are concerned that allowing prairie dog populations to cover too much of the suitable habitat at any one time threatens the viability of this habitat. We have observed areas with peak populations that have become virtually denuded of vegetation. During the high wind events in January 2009 we observed dust storms emanating from one such area on open space land near Highways 93 and 128 that made driving unsafe. We do not believe bubonic plague is a good management device for regulating numbers of prairie dogs.
We recognize prairie dog management is one of OSMP’s greatest challenges. The plan provides much better information about the extent of OSMP lands suitable for prairie dog habitation as well as about other ecosystem considerations. We support implementation of the plan’s actions respecting prairie dogs.
2. Respecting fire
Lack of fire appears to be one of the most important missing ecological drivers for our grasslands. We appreciate the complexities of controlled burns but believe fire is essential if the prairie systems are to improve. We encourage OSMP to work on public education about the importance of fire in maintaining healthy grasslands and to continue efforts to utilize controlled burns when possible.
3. Respecting grazing
The report identifies concerns about a homogenization of vegetation communities in both the mixedgrass and mesic bluestem areas and notes the potential adverse effects of livestock grazing in this regard. With this baseline condition respecting vegetation now in place we would encourage a review of livestock grazing practices and some experimentation with altered regimes to test effects on vegetation.
4. Respecting animal species composition, vegetation composition, and habitat effectiveness
The report identifies animal species and vegetation composition as key attributes for the three prairie types. It identifies as indicators for animal species composition the percent occurrence of sensitive butterflies and skipper species, the percent occurrence of grassland dependent butterflies and skipper species, and percent of target with acceptable bird conservation score. As indicators for vegetation composition it identifies native species relative cover, native species richness, percent of target with prevalence of non-native species, and richness of selected conservative plant species.
We wonder about the utility of utilizing such broadly descriptive attributes rather than focusing on attributes that help identify the ecological processes essential to conservation of the target. Thus, for example, in a recent TNC report there is the following explanation of attributes:
To identify what is most important to manage for the conservation of biodiversity in focal areas, we first identify a limited number of biological characteristics, ecological processes, and/or interactions with the physical environment—along with the critical causal links among them—that distinguish the target from others, shape its natural variation over time and space, and typify an exemplary reference occurrence (Maddox et al. 2001). Some of these characteristics are especially important, influencing many other characteristics of the target and its long-term persistence. We label these characteristics of a target its key ecological attributes.
The main premise of The Nature Conservancy’s conservation framework is that key ecological attributes must be managed and conserved to sustain each conservation target (Parish et al. 2003). By explicitly identifying such attributes, land managers can specify what elements of a specific conservation targets are important to manage and monitor in order to assess conservation progress.
The key ecological attributes of a conservation target include not only its biological composition (and crucial patterns of variation in this composition over space) but also the biotic interactions and processes (including disturbance and succession dynamics), environmental regimes and constraints (again including disturbance dynamics), and attributes of landscape structure and architecture that sustain the target’s composition and its natural dynamics (Noss 1990, 1996, Noss et al. 1995, Christensen et al. 1996, Schwartz 1999, Poiani et al. 2000, TNC 2000a, Young and Sanzone 2002). Identifying key attributes that address more than just biotic composition is important for two reasons. First, the abundance and composition of a target may lag in its responses to environmental impairments. Data on biotic interactions, environmental regimes, and landscape structure can help ensure the early detection of threats and changes resulting from human activities. Second, conserving the focal targets is not the ultimate goal but a means for conserving all native biodiversity in an area. Consideration of these additional types of key ecological attributes will further ensure that crucial aspects of ecological integrity are managed for the conservation of all native biodiversity.
Development of a baseline identifying animal and plant composition provides a marker against which to measure change. More important, however, for purposes of management is to identify those factors that shape and sustain this composition. We are not sure the present analysis does this.
5. Respecting locations of rare plants
We agree with the statement that “[f]amiliarity with the location of rare plant populations and the habitats used by these species allows OSMP to avoid or minimize site-specific impacts from trail construction, agricultural management, and other activities. Identification of the ecological drivers that explain the presence of these rare plants also seems important. An example is the kind of analysis that has been done to understand the presence of Ute Ladies –tresses.
6. Respecting management of non-natives
We agree this is both a good indicator of ecosystem health and an on-going management need. We would like to see some analysis of locations with high densities of non-natives to help better understand why they have moved into certain areas and what can be done to prevent such encroachment in other vulnerable areas.
7. Respecting the shale barrens
We would support the closure of these areas to all visitation. They are unique, sensitive, and do not occur widely. With appropriate public education about their values, we believe the public would support such a closure.
8. Respecting White Rocks
This unique area is currently largely within conservation easements. Thus, access is limited. While we would prefer fee ownership of this important area we would only support purchase if it was conditioned on maintaining controlled access through permits.
9. Respecting Implementation
We are pleased to see this initial effort at identifying conservation objectives and strategic actions. We fully support the objectives of improving vegetation composition and structure in Best Opportunity Areas, enhancing avian habitat, maintaining occurrences of rare butterflies and increasing occurrences of grassland-dependent butterflies, and reducing presence of invasive species. These objectives appear to be fully consistent with the preceding analysis respecting the health of the grasslands. For purposes of public education we would encourage some discussion of these objectives to provide an explanation of why they were selected. We would also encourage consideration of organizing the presentation of objectives in Table 25 so that related objectives are connected. At present the list appears somewhat random. We would also encourage consideration of relating the list of strategic actions directly to the conservation objective(s) it would help accomplish. The list in table 26 is tied to a ranking that emphasizes viability but does not connect to purpose. Then the shift to the five initiatives requires still another reorganization of the pieces. The purpose of this last reorganization is unclear and difficult for the general reader to follow.
10. Respecting Consideration of Climate Change
Professor Seastadt, who is a member of the FOBOS Science Advisory Group, provided staff with extensive comments last November respecting the plan that discuss the changes that have been identified related to climate change that are affecting grasslands. Among other things, these changes favor the increased presence of certain vegetative species and disfavor others. He encourages staff to take these changes into account in developing their conservation targets and in determining appropriate management actions. Consequently, we would encourage OSMP to practice natural resource conservation to consider the effects of climatic variability on natural resources and climatic shifts over the next few years to decades.
11. Respecting Sustainable Management
The wisdom in this Ecosystem Management Plan is the fact that the focus is on managing for sustainability of a mosaic of many different grassland eco-types (including the soils, vegetation and non-plant species) in an integrated way – and NOT managing for individual species. In addition, the critical importance of LARGE blocks of land is key.
Our Response to Comments
The February 11 memo to the Board suggests that many of the comments on the draft plan focus on visitor and recreation use concerns. We hope review of the draft plan does not get sidetracked by these concerns. We spent six years developing the Visitor Master Plan. That entire discussion occurred in the absence of the kind of information that is now contained in the grasslands plan. Let’s use this time to concentrate on understanding the lands and their natural resources. Let’s focus on their condition. Let’s identify what is important to us about these lands and natural resources, what natural attributes we want to ensure remain in healthy functioning condition so that they can be enjoyed by not just us but by future generations as well. Once we have achieved this level of comprehension and have put in place a process for achieving and maintaining the desired conditions we can better consider appropriate ways for us to use and enjoy the lands.
Consider the identified concerns. One relates to the recognition that riparian areas are exceptionally important habitat for a wide range of biodiversity; thus we should seek to limit social trails in these areas. The scientific basis for this stated management objective is powerfully documented. Establishing a goal of reducing trails in such areas is entirely consistent with our understanding of the unique importance of riparian areas in places with such limited water. No actions are taken under this plan. It is guidance for consideration in future TSAs.
The concerns suggest that people should never be excluded from riparian areas because they are pleasant places to recreate. Indeed, the entire Boulder Creek bikepath provides the opportunity to recreate within a riparian area. Many of our designated trails provide that experience—more than many of us think are needed and certainly more than would be desirable from a biological perspective. The plan accurately reflects a recognition of the special importance of riparian areas and only proposes the goal of reducing trail densities in such areas. OSMP comments further state the department’s intention only to address undesignated trails. While we agree that removing undesignated trails should be the first priority in each TSA process, we oppose restricting this consideration only to undesignated trails. We believe there may be a few existing trails that currently are located in high value riparian areas that should be considered for either rerouting out of the riparian area or should be closed.
Another concern was that protection of grassland bird nesting areas would interfere with recreational uses of the areas. Again the report accurately acknowledges both the existence of such nesting areas on OSMP lands and the scientific studies documenting the effects of human, equestrian, and dog presence on the success of such nesting use. The conclusion is that we should consider opportunities for seasonal trail closures for trails identified as especially close to the nesting areas, that we should emphasize on-trail use by hikers and equestrians in such areas, and that dogs should be required to be on lease in these areas. In our view these are entirely reasonable proposals that can and should be considered during TSAs.
We note the VMP, in its Resource Protection Initiative, states:
Visitor impacts that degrade or diminish the quality of natural, agricultural, or cultural resources should be minimized. The most significant potential impact from visitor activities is through visitor travel or access. This initiative is intended to: (1) direct visitors away from areas with highly sensitive resources; ….
Had the grasslands plan be in place before the VMP we would have already identified riparian areas and grassland nesting areas as sensitive.
Appendix A – Boulder’s Amazing Grasslands
By maintaining an undeveloped buffer of land around the City of Boulder, we have also protected some very special habitats. The recent draft, Grassland Ecosystem Management Plan, prepared by OSMP staff, documents the remarkable qualities of the grasslands protected as city open space.
Did you know our grasslands support more than 800 species of vascular plants and over 400 species of vertebrates?
Grasslands account for about 24,000 acres of city-owned open space and another several thousand acres of land protected under conservation easements. Other grasslands in the area are protected by the county, by NOAA (Table Mountain), and by the U.S. Fish and Wildlife Service (Rocky Flats National Wildlife Refuge).
The dominant grassland type is the mixedgrass prairie mosaic, accounting for about 40% of the total. Common species include western wheatgrass, needle and thread grass, green needlegrass, New Mexico feathergrass, sideoats grama, little bluestem, and Rocky Mountain bluegrass. Common shortgrass species include blue grama and buffalograss. This mosaic supports numerous grassland nesting birds, badger, and elk as well as the black-tailed prairie dog. More uncommon species include the short-horned lizard, olive-backed pocket mouse, and several rare butterfly species.
Located in unique areas in which shales of the Niobara and Pierre formations outcrop, these barrens provide habitat for a large portion of the habitat for Bell’s twinpod, a globally rare and state imperiled endemic species, along the Front Range of Colorado.
Next most widespread is the xeric tallgrass prairie, a vegetation type considered rare and imperiled globally and in Colorado. These tallgrass communities are found in rocky soils at elevations between 5,400 and 7,600 feet where the prairie meets the mountains. This tallgrass habitat is especially important for certain butterflies, including the Ottoe skipper, Arogos skipper, crossline skipper, and regal fritillary. Large, unfragmented patches of xeric tallgrass provide seasonal habitat for a number of grassland nesting birds.
Open space contains about 350 acres of mesic bluestem prairie, the largest remnants of mesic bluestem in the state. This vegetation type is one of the most endangered in the world. In recognition of its importance, the Colorado Natural Area’s Program designated this area of open space as the Colorado Tallgrass Prairie State Natural Area in 1984.
Black-Tailed Prairie Dogs
Black-tailed prairie dogs are considered a “keystone” species in grassland habitats. Populations on open space vary widely. In 2005, 3,500 acres of open space grasslands supported prairie dogs. In 2008, only 1,700 acres contained prairie dogs. Other species associated with prairie dogs include burrowing owls, American badgers, ferruginous hawks, and golden eagles.
Wetlands are found on about 1,500 acres of open space. Wetland types vary widely and include marshes, wet meadows, and riparian wetlands. Such areas contain a disproportionately high level of biodiversity. Rare plant species include the ESA-listed Ute ladies’-tresses orchid and the Colorado butterfly plant. Rare butterfly species found associated with open space wetlands include the prairie Arogos skipper, the prairie regal fritillary, and the two-spotted skipper. Rare birds found in wet meadow habitat include the bobolink and the savannah sparrow. Another species of concern found in these wetlands is the northern leopard frog.
Riparian areas adjacent to perennial and intermittent creeks account for about 1,200 acres. These transitional areas support an unusual concentration of plant and animal life. Of special interest because of their limited presence elsewhere is the Narrowleaf Cottonwood/Bluestem Willow Woodland plant association and the Red Hawthorn plant association. They help protect and enrich the important stream environments of Boulder Creek, South Boulder Creek, and Coal Creek among other drainages. These areas support the highest concentrations of breeding bird populations of any place on open space.
Protected under conservation easement and partially designated as a Colorado Natural Area, the White Rocks cliffs are outcrops of light colored Fox Hills sandstone near Boulder Creek. The unique conditions provide habitat for two rare plant species: the black spleenwort and the American groundnut. Also found here are several species of birds and invertebrates uncommon in Boulder County.