An Ecosystem Management Plan for City and County Open Space Lands

(A slightly modified version of this essay was published on the July 17 1997
issue of the Boulder Weekly).

Tim Seastedt

     The purpose of this article is twofold. First, I want to explain why
current management activities of Open Space lands are inadequate to
maintain these lands in some approximation of their pristine condition.
Second, I want to suggest management activities that are more appropriate
for the goals of restoration and preservation. This new management
program must actively involve the citizens of Boulder County if it is to
provide the type of Open Space that is desired, affordable, and in
compliance with environmental regulations.

     My recent involvement in Open Space activities is not driven by an
interest in weed control. However, the fact that the major management
activity of Open Space is weed management emphasizes my main concern. The
system is rapidly changing and current activities, mostly combinations of
conservation of individual species and weed control, are not up to the job
of preserving or restoring whole ecosystems. 

     Land management implies that a specific area is designated to perform
some service(s) or function(s). The application of some practices like
seeding or mowing, etc., where anticipated effects of the treatment are
based on previous knowledge, is scientific management. The newest approach
to land management is "adaptive ecosystem management", which has yet to be
adequately defined.  This form of management attempts to address the fact
that ecosystems are changing as a result of internal and external forces.
Adaptive ecosystem management employs current information from
ecosystem science in management strategies for ecological communities
being influenced by these changing environmental conditions. 

Why Current Management is Inadequate.

     Open Space is changing, and conservation management activities that
focus on individual species do not address these changes. The vegetation
composition of Open Space only marginally resembles that found here 100
years ago. Large tracts of intact prairie and savanna now are fragmented
among subdivisions. These subdivisions are refugia for non-native and
native (but urban) wildlife that make regular incursions into the
surrounding landscape. Trails provide access to most areas not adjacent to
developments. Hence, no area of Open Space is immune to visitation,
modification, and colonization by a new suite of species.

      Fires were common along the Front Range.  Most areas experienced a
fire about once every 10 years or so. Fires were probably least common on
the shortgrass prairie found in eastern portions of the county, while fires
were most common in the more productive grasslands adjacent to the
foothills. Fires had a remarkable number of direct and indirect effects on
ecosystems. Some species are directly harmed; many species are directly or
indirectly benefited. An important point to remember is that the native
species are adapted to ecosystems that experience frequent fire. While
individuals may be harmed, populations are ultimately benefited. The
removal of dead plant materials from the grasslands greatly alters the
amount of water, light and nutrients reaching the soil surface, and the
subsequent fate of those resources are controlled, in part, by the
composition of the vegetation benefitted by the fire. In the absence of
fire, the amount of dead plant material slowly shades out the native
vegetation, allowing for the invasion of both native woody species, such as
ponderosa pine, and non-native trees such as Russian olive.

     The substitution of non-native grazers as an alternative to frequent
fire was an unintentional management practice initiated by the early
settlers of the region. The ranchers were out to raise cattle, not control
fires, but the management activity resulted in fire suppression. Since
grazers remove plant material and prevent dead plant litter accumulation,
grazers have a short-term effect very similar to fire. However, fires
consume all fuel; cattle are selective. Fires send nitrogen up in smoke;
cattle create urine and fecal patches of nitrogen fertilization. And, while
the native bison herds undoubtedly grazed here prior to European
settlement, the bison clearly did not function effectively in fire
suppression. Their presence was ephemeral and probably infrequent on a
yearly basis. The 10-year fire frequency occurred in spite of bison's
ability to reduce the fuel load. If we look at other heavily grazed systems
such as the Serengeti of Africa, we also see a major role of fire in
seasonally dry areas such as ours.

     In contrast, chronic and often year-around grazing by cattle in
fenced meadows has resulted in many changes not observed under a frequent
fire regime. Irrigation has increased the productivity of many meadows, but
the timing and duration of water on and within the soil has 'changed the
rules' regarding what plant species benefit from this water. For example,
most of the grasses that dominated our region were most active in mid to
the later portions of the summer, when water was scarce. These same
species cannot compete with introduced grasses capable of growing during
cooler times of the year on irrigated lands. Since the species that can
initiate growth in the fall or early spring can potentially use up the soil
water and nutrients before the warm season grasses become active, the
cool season species have an advantage. Fires during the fall or spring must
have been more common than midsummer fires and such fires would have given
the competitive edge to the warm season grasses.

     Our current agricultural and industrial activities have produced a
number of off-site effects in the form of water and air pollution that
affect us. One effect was, until very recently, not seen as a problem at all
but a benefit. Our activities have greatly increased the amount of plant-
usable nitrogen found in rainwater and atmospheric particulates. This is
fertilizer, and plants respond accordingly.  However, besides growing bigger
plants, the presence of fertilizer also changes the competitive
relationships among the plant species. Fast growers like weeds tend to
benefit more from fertilizer than do slow-growing species, and weeds
become more abundant under higher amounts of fertilizer. (Indeed, the use
of "weed and feed" rather than just "feed" for our lawns recognizes this
fact.) The insult to Open Space lands, however, is that this fertilizer
effects further encourages changes in the composition of the vegetation.
Again, the evidence suggests that the species that grow in the fall or
spring are benefited more than the once-dominant warm season grasses, and
the combination of the lack of fire and fertilization is now the major causal
agents for change in plant species composition on Open Space.

     What we have done over the last 100 years is to remove the Front
Range ecosystems from their historical range of variability generated by
natural disturbance events. The dominant native species did not evolve in a
fire-suppressed, chronically grazed, and fertilized condition. These
species now are succumbing to (what were rarer) species that have evolved
under those conditions. To add to the problem, on top of these
environmental changes has come an army of species from other parts of the
world. Some of these species are adapted to the cooler, wetter conditions
we have created by fire suppression. Some of these are distasteful to
cattle and have benefitted greatly from selective grazing. Many of the
exotic species have arrived without their normal predators or parasites.
The combination of right climate and atmospheric fertilization, reduced
competition from native species, and absence of adequate biological
controls has created the "noxious weeds" a problem that, in the decade in
particular, has surfaced as a major threat to native species.
     
     As an ecologist, I formerly dismissed weeds as a threat to natural or
seminatural ecosystems. After all, the native species evolved under the
local conditions and should be better competitors, right? Weeds were a
problem of agriculture and disturbed and degraded sites. However, weeds
are species that benefit from the reduction in competition for resources
as well as by human disturbances. Given the current amount of human-
caused stress and disturbance corridors on Open Space lands, the exotic
weed problem should be no surprise. 

Will Ecosystem Management Work?

     Ecosystem management would attempt to restore the historical range 
of variation generated by natural disturbances that were responsible for
the establishment of the native grasslands and savannas of the Front
Range. Ecosystem management would attempt to remove the atmospheric
fertilizer effect as well. Management activities would favor those
environmental characteristics that gave the native warm-season grasses
the ability to dominate the region. The dominant species would create the
environment that supports the rarer (and now likely candidates for 'rare
and endangered') species. Even those that want to develop the rest of
Boulder County should understand that keeping these species off the
endangered species list is a major economic incentive to ecosystem
management. One way to keep them off is to keep them fairly common and
abundant on public lands.

     I believe there is little or no hope for maintaining or restoring the
natural biological structure and function of Open Space lands without using
recurring fire as a management tool. If the City and County collectively own
about 30,000 acres that have been chosen as 'pristine grasslands and
savannas', then we should be burning about 3,000 acres of Open Space
annually to meet this disturbance requirement. Similarly, there's little
hope of restoring the native mixed- and tallgrass species in the face of
chronic grazing. If we agree that conventional grazing must remain on some
of Open Space lands, then we should probably abandon efforts to maintain
these in any sort of native state but use them for whatever conservation
values they afford. Adaptive ecosystem management recognizes a number of
'ecosystem services' that non-native lands can provide. Properly managed
grazing lands may not provide much to biodiversity efforts, but can
contribute to clean air and clean water efforts.

     This is what the our community needs to address. If large portions of
Open Space are to remain in somewhat pristine conditions, a more proactive
management approach is required. There are some potential conflicts in
these choices. Some Open Space lands were acquired with requirements for
agricultural activities. Fire scares people and represents an obvious
environmental risk that many managers want to avoid. Moreover, since our
air is now being influenced by the activities of about 2.5 million people on
the Front Range, air quality considerations may preclude fire as a
management tool (since adding natural 'pollution' to anthropogenic pollution
could exceed guidelines). 

     Already, there is substantial risk that imposing traditional
disturbance regimes may not immediately restore the native grasses. The
system has changed so dramatically that fire, for example, when imposed on
the current vegetation that is strongly influenced by cool-season, non-
native species, may produce some very unexpected results. Restoration may
be both difficult and a tricky enterprise. Some time-tested techniques may
not work, and nontraditional management activities (say, attempting an
early summer mowing and haying operation to stimulate the warm-season
grasses) may be needed.
 
     There are no laws that mandate ecosystem management. Existing laws
focus on species protection and ecosystem services such as water and air
quality. Given the current laws with respect to rare and endangered
species, we can predict large numbers of litigation activities as the
endangered list of species grows exponentially. This is why I argue that a
proactive effort to maintain the systems in as native a state as possible
is desirable both ecologically and economically.

     What needs to be done? I am voicing an action plan already endorsed
by land managers. I suggest a series of both neighborhood and county-wide
town meetings between the stakeholders and land managers to initiate site-
specific plans. The maps and technology exist to quickly transform
proposals into documents that could be adequately discussed and debated
regarding the desired composition of Open Space lands. These same maps
could provide the monitoring and documentation of progress towards goals.
The tradeoffs of all activities on Open Space need to be explored, so that
goals and management activities that are most likely to obtain those goals
can be implemented. I believe that some parcels of Open Space may be too
small to be managed in a natural state, at least, not without fairly
substantial human intervention and financial support. Adjacent land uses
may preclude certain management activities. However, all of these problems
need to be aired publicly. I also suggest that City and County managers
attempt to become much better neighbors with the private sector that owns
adjacent lands. While Open Space belongs to everybody, the potential to
involve adjacent owners as special stewards of these lands should be
explored. Collectively, this could and should blossom into long-term "adopt
a prairie" activities that could function in many roles protecting,
maintaining and enhancing Open Space.


Seastedt is Professor of EPO Biology, University of Colorado, and
Past President of The Association of Ecosystem Research Centers. Views
expressed herein are those of the author.