Joshua Tree National Park is a remarkable desert ecosystem made iconic by the famed Joshua trees that dot the landscape. In 1994, a majority of Joshua Tree’s holdings were designated as “wilderness” (a legal status in the U.S.). Subsequently, Joshua Tree was buffeted by deleterious anthropogenic forces and suffered from severe budgetary constraints. In 2018/2019, a U.S. Government shutdown forced the Joshua Tree staff into furlough, while the park remained open to visitors. The response of local volunteers, who took responsibility for educating visitors about park policies and ecosystem conservation in the midst of the shutdown, shows the extent to which networks of local and community volunteers can be mobilized to mitigate at least some of the effects of budgetary constraints that affect the wilderness and national park lands.

KEY MESSAGE

Students will begin by considering how, in the presence of funding shortages and a dual mission of conservation and recreation, land managers can build networks of local and community volunteers who aid in park management through educating visitors about park policies and ecosystem conservation. Students will think about how the involvement of local and community volunteers can (1) help ameliorate budgetary shortfalls in wilderness lands and national parks, and (2) build networks of volunteers who educate visitors about park policies and ecosystem conservation and can help with the backlog of park projects that do not have funding.

INTRODUCTION

Joshua Tree National Park (hereafter Joshua Tree or the park) is a 792,510 acre desert park that contains a remarkable desert ecosystem. The park is located in southern California, only a few hours from Los Angeles, and is dotted with adjacent towns. The heart of the park is surrounded by low mountains, cutting off all sightlines of the local towns and making it seem like a vast wilderness. The iconic Joshua trees, after which the park is named, sprout in small forests across the park, creating an eerie and beautiful effect with their tall stalks and branching, spiky arms.

Like all national parks, the management of Joshua Tree has to strike a balance between two mandates (recreation and conservation) while working with a razor-thin budget that does not cover their maintenance backlog. This park is increasingly affected by climate change and other anthropogenic threats. It is particularly susceptible to damage from visitors due to its popularity. The park is close enough to Los Angeles, CA; San Diego, CA; Phoenix, AZ; and Las Vegas, NV, that it brings in millions of visitors every year (just ≤3 million during 2018). There have been record breaking numbers of visitors for every year from 2015 to 2018. At the end of 2018 and beginning of 2019, Joshua Tree experienced these record-breaking visitation numbers while the U.S. Federal government was shut down. Because there was no oversight of visitors at that time, the park incurred major damages. The park ecosystem will take hundreds of years to recover from this damage.

While the government shutdown resulted in significant damage within Joshua Tree, there was one positive outcome: local communities and NGOs increased their engagement with the park. This paper uses Joshua Tree and the impact of local communities and NGOs as a case to show that strengthening stakeholder collaborations between national parks, local volunteer groups, and NGOs into volunteer-based educator networks is crucial for the national parks to balance their dual mandates in the midst of funding shortages. Using volunteers in national parks is not a new idea and has been encouraged by the leadership of the National Park Service. There is even a handbook created by the Midwest Region of the National Park Service on how to build Friends groups that can help the park with their projects [1]. The case of Joshua Tree shows how volunteers can help national parks through a crisis, and the lessons learned there can be extrapolated to the use of volunteers to achieve everyday goals in national parks.

CASE EXAMINATION

Legal Aspects of U.S. Wilderness Lands: Managing the Wild

Joshua Tree is one of the many U.S. National Parks that contains legally designated wilderness areas; lands where the human presence is minimized and that are managed stringently for low-impact recreation and their ecological values. Wilderness within public lands is specified through inclusion within the National Wilderness Preservation System, which was set up following the 1964 Wilderness Act. All of the U.S. land management agencies (the National Park Service, the U.S. Forest Service, the Bureau of Land Management, and the U.S. Fish and Wildlife Service) administer wilderness areas. In practice, wilderness area management is largely at the discretion of the agency overseeing the area. The Wilderness Act does not allow for mechanized transport or interference in the land (bikes, helicopters, chain saws, etc.), and only “primitive” approaches may be taken by visitors and managers. Once a land is designated as wilderness, no “permanent improvements or human habitation” can be added [2]. There are exceptions to this rule. Managers of wilderness areas sometimes find it less impactful to an ecosystem to use mechanized solutions (such as when mine remediation was needed in Joshua Tree and it was determined that using a helicopter for a short time would have less ecological impact than using a team of burros for several days to weeks).

The 1916 Organic Act created the U.S. National Park Service and the National Park System and required that the parks be maintained for both recreational use and resource conservation [3]. In addition to the mandates laid out in the Organic Act, many national parks are subject to additional legal requirements. For example, the Endangered Species Act (1973) applies to all public lands where an endangered species is present. It directs conservation of species habitat and requires that the management does not further threaten that species or its habitat. Joshua Tree is also subject to the California Desert Protection Act [4], which expanded the wilderness area within Joshua Tree. Today, the wilderness area within Joshua tree covers 594,502 acres of the 790,636 acre park.

All national parks operate under their own General Management Plans [5], which determine how natural resources, public access, and education will be undertaken within the park. General Management Plans are created by the park leadership, in conjunction with scientists and specialists. The extent to which national parks are capable of operating on their General Management Plans is dictated by their annual operating budgets, and these budgets are set by the U.S. Congress and the U.S. Department of Interior.

All national parks deal with funding shortages when congressional appropriations do not match the needs of the National Park Service. In 2017, 2018, and 2019, the budget for the National Park Service operations increased slightly [6], but this did not address the fiscal needs of the parks. When inflation is taken into account, the increased operating budget shows even more stark shortfalls. In 2017 and 2018, the National Park Service was already suffering from staff and funding shortages when an estimated amount of >11 billion USD was needed for repairs, maintenance, and protection projects [7]. With the inclusion of the serious damages incurred during the government shutdown of 2018/2019, this number has risen significantly. In addition, during the shutdown, the furlough of park employees meant that parks were not able to collect access fees, further adding to their deficits. These fees (at least 80% of which goes to the park that collects the fee, and the remainder is allocated to parks that do not collect fees) are used for the backlog of maintenance, repairs, and conservation works that need to be done in each park [8].

Balancing a Dual Mandate within Joshua Tree: Recreation and Conservation

Joshua Tree, like all national Parks, is a land designated for two primary purposes, namely, recreation and conservation. Recreation at Joshua Tree primarily consists of hiking, camping, climbing, and backpacking; visitors flock to the park in large numbers throughout the year, particularly in the late fall through early spring months [9]. It is also a cultural resource, with many visitors attracted to the Native American historic sites and historic mines within the boundaries of the park. Many different outfitters are based around the park and rely upon the steady flow of tourists. The adjacent towns thrive on revenue from the tourism industry, generated by their proximity to Joshua Tree, and the town of Twentynine Palms (where the visitor center for Joshua Tree is located) also houses a US Marine Corps base.

Due to the popularity of Joshua Tree, its location near a military base, and its proximity to Los Angeles, the park confronts a host of anthropogenic and environmental issues. In addition to recreational traffic, air pollution due to proximity to Los Angeles and Palm Springs affects Joshua Tree, leading to nitrogen deposition in the western side of the park [10]. The excess nitrogen encourages the spread of non-native grasses (e.g. cheatgrass and red brome), which puts the park at risk for wildfires and requires management to remove these grasses so that they do not take hold within the wilderness area [11]. In addition, the park is hemmed in on all sides by highways that interfere with the natural migration routes of species, including the endangered desert tortoise. The addition of culverts under the roads allow for the movement of desert tortoises, but larger species, such as the park’s herds of bighorn sheep, have no such protected means to cross the highways. The roads also increase pollution and litter at the boundaries of the park and worsen ecological degradation.

The iconic Joshua trees of Joshua Tree National Park are highly vulnerable to climate change and anthropogenic disturbances. As temperatures rise, the trees’ distribution within the park is shifting toward higher elevations and toward refugia (located in canyons and ravines) where moisture is more easily retained [12]. Exotic grasses and tamarisk encroaching from the western edge of the park threaten the Joshua trees’ redistribution in the face of climate change. In drought conditions the exotic grasses exacerbate wildfires. As the grasses and tamarisk spread they outcompete native plants, reshaping refugia and choking out the spread of young Joshua trees. Tamarisk, in particular, choke waterways and take up all available water in an area. To ensure the continued existence of Joshua trees, intensive ecosystem management needs to be undertaken to stop the spread of these exotic grasses and tamarisk into the refugia that shelter young Joshua trees.

Two labor-intensive processes are necessary to protect refugia within Joshua Tree. First, firebreaks—large gaps in vegetation and/or trenches—need to be dug around the refugia sites to protect them from wildfires [13]. Second, exotic grasses and tamarisk need to be removed from the refugia so that they do not outcompete young Joshua trees. Because 75% of Joshua tree is a wilderness area, neither of these processes can be undertaken with heavy machinery nor with modern techniques. Firebreaks need to be dug by hand, and the exotic grasses and tamarisk need to be cleared with hand tools and pulled by hand. However, Joshua tree has neither the staff nor the budget to undertake such extensive ecosystems management.

The Management Plan for Joshua Tree was established in 1995, after the California Desert Protection Act changed Joshua Tree from a National Monument to a National Park and expanded the wilderness areas. The conservation actions outlined in the General Management Plan at Joshua Tree are general and focus on overall strategies. In 2006, the administrators of Joshua Tree developed the current Management Policies, which address specific policies for park management [14]. These policies guide actions such as removal of exotic species (such as tamarisk and fountain grass), protection of sensitive ecosystems and species, and protection of cultural and ecosystem resources.

The dual mandate of the National Park Service and the ensuing problems concerning how to preserve and encourage visitor use of national parks stem from the assumptions made by the founders of the 1916 Organic Act. The founders of the National Park Service assumed that all undeveloped lands were unimpaired (not affected by development and people visiting) and, therefore, they were preserved [15]. This belief led to a large focus on visitor experience and development of roads and concessions in national parks to make them more accessible for recreationists. The NPS dual mandate prompted scientific attempts to restore ecosystems within the park. With increased interest and visitation to national parks, the balance between recreation and conservation has been difficult to maintain. Because the roads and buildings were developed early in national park history, there have been considerable visitor impacts on park landscapes, and preservation efforts are often hard pressed to keep up. Subsequent park policies have tried to smooth the way to pursue both of these mandates, though some subsequent laws have made it difficult. For example, wilderness areas can be seen as perfect for preservation unless there is an ecological restoration project that a manager wants to pursue; additionally, wilderness can be seen as contrary to the encouragement of some types of visitor enjoyment because bikes or mechanized travel are not allowed. Congressional amendments to the Organic Act in the 1970s attempted to call for more action for park preservation, but the wording was often ambiguous from the management perspective. Today, the debate continues over what the management focus should be for the National Park Service [16].

Park managers at Joshua Tree are thus faced with oversight of a massive public park and wilderness area that face serious anthropogenic threats while attempting to fulfill their mandate for recreation and conservation under tight fiscal constraints that do not permit all problems to be addressed in immediate or sustainable ways [17]. The problems with balancing the dual mandate of recreation and conservation in the face of budgetary shortfalls are not unique to Joshua Tree—they affect all national parks. Yet, the case of Joshua Tree may offer a solution to help park management ameliorate these problems. And this solution comes from one of the unlikeliest of places—the longest government shutdown in U.S. history.

The U.S. Government Shutdown of 2018/2019 and Implications for Managing Recreation and Conservation at Joshua Tree

In December 2018, parts of the U.S. government shut down due to a disagreement between the congressional and executive branches over an appropriations bill to fund the U.S. government for 2019. One part of that bill was funding for the U.S. National Parks. Because the bill was not approved before the previous funding lapsed, the U.S. National Parks were shut down until the funding bill was passed. At the beginning of the shutdown, nearly all Joshua Tree staff were furloughed. Only eight rangers (who were not being paid at the time) were retained to maintain the park. Despite the rangers’ best efforts, the park suffered extensive damage. Litter and human waste, which are normally disposed of by the Park Service employees, were not removed, leading to overflowing restrooms and garbage bins [18]. Visitors drove vehicles through critical habitats, camped illegally, wandered off trail, spray painted graffiti on the rocks and boulders, let their dogs off leash in protected areas, and, perhaps most distressing of all, cut down Joshua trees. The park could take hundreds of years to recover from visitor damage, according to Curt Sauer, a former superintendent [19]. Moreover, the park lost access fees during the shutdown and had to spend some of their reserve budget to bring employees back to work before the shutdown was over [20].

During the shutdown, the local community and NGOs (e.g., the Friends of Joshua Tree National Park [20]) worked together to educate visitors and mitigate the damage. People like John Lauretig (leader of the Friends of Joshua Tree) organized groups to go into the park, and other local people and volunteers went campsite to campsite, gathering support and asking people to help by cleaning up after themselves and following the rules. Volunteers stationed themselves at park entrances and stopped incoming cars to explain park policies. They walked the trails and roamed the campgrounds, educating visitors about conservation and helping to clean up messes [21]. Volunteers even “put up signage about being a better human, not destroying the park, and what to do in the park” [21]. The extent of volunteer involvement and their efforts to both educate visitors and aid in conservation led a visiting employee from another national park to comment that they were “completely shocked at the level of engagement from the volunteers” [21]. In addition, the Friends of Joshua Tree group also offered zero-interest small loan programs to help furloughed workers who were affected by the shutdown. These financial efforts from local groups helped to ensure that employees remained with the park, instead of seeking new employment. After the shutdown, volunteers from the community and the Friends of Joshua Tree continued to help. They volunteered to assist the overwhelmed, newly returned park staff with cleanup. One of the well-known advocates and volunteers in the area, Rand Abbott, helped with the cleanup and asked people to be more careful and conscientious, and less destructive. He persuaded some visitors to be more careful and to stick around and help clean up some of the trash [22].

The extensive involvement by community volunteers and NGOs at Joshua Tree in educating visitors and undertaking conservation efforts during the 2018/2019 government shutdown highlights the extent to which stakeholder collaborations can positively affect national parks. The administration at Joshua Tree, as part of their 2006 Management Policies, list cooperative conservation as one of the resources that the park could draw on to mitigate anthropogenic factors that affect the health and well-being of the ecosystems within the park [14]. While community organizations and NGOs have long been engaged with Joshua Tree, this case indicates that they can become an even more powerful part of the park’s management plan. The park has previously worked with local NGOs and other groups on various projects, but that relationship could be leveraged to help cover funding and staffing shortfalls. As discussed above, such a strengthened community-based education and conservation network could help national parks to balance their dual mandates in the midst of funding shortages.

CONCLUSION

If current trends continue, Joshua Tree will continue to see increased visitor use in the coming decades. Since 1941, the park has seen fairly consistent increases in visitation over most years; some time periods show a slight dip, but then the numbers start rising again. From 2015 to 2018 the numbers increased every year (with 2018 showing the lowest increase of just <89,000, to record a total number at just <3 million visitors) [23]. The proximity of Joshua Tree to large cities and the recreation afforded within the park make it a very attractive destination. Increased visitation, coupled with visitor-induced damage, the dual mandate of national parks, and budgetary shortfalls have put Joshua Tree, along with many other national parks, into a difficult position. In the future, without increased funding for national parks, access may need to be restricted to mitigate damage and manage conservation efforts. However, there is a way forward, which does not rely solely on the funding whims of the U.S. federal government: through increased involvement of local, community-based volunteers. As the case study outlined above shows, community involvement in educating visitors and in conservation efforts can help to relieve the stressed National Park System. The solution of strengthening already extant local, community-based volunteers into networks that collaborate extensively with the national parks is discussed below, with reference to how such a network can be mobilized for ecosystems management as well as education and outreach.

Educating visitors is an initiative of all national parks, and it usually consists of informing visitors about the history and ecosystems of the parks. But education can take many forms, including informing visitors about park policies and the necessity for conservation, and outreach to local communities to inform them about the parks’ valued landscapes, recreational opportunities, and conservation efforts. Education about park policies and the necessity for conservation is usually done through pamphlets, signage, and patrolling park rangers. One of the main efforts of volunteers during the 2018/2019 government shutdown was informing visitors about park policies and their relationship with conservation. By strengthening their network of educational volunteers, Joshua Tree could continue these actions. If these volunteers could offer coverage of heavily trafficked areas to interact with visitors and help them to understand the rules of the park and why those rules are in place, it would help spread the word to visitors who might not have much interaction with the park staff (like the visitor center staff or rangers in the park). Using volunteers inside the park to educate people at trail heads and camping facilities can expand the impact of education initiatives.

The park has worked with volunteer groups in the past to remove exotic grasses, tamarisk, and other exotic plants [11]. Due to the prior use of volunteers to remove exotics, there is already a model in place for using volunteers on land management projects. This should become a more robust and routine method used to approach land management and maintenance. Through working with local and national NGOs, the park can undertake management approaches that will be more impactful. Strengthening the networks of conservation volunteers willing to do the hand work of saving refugia and creating firebreaks will allow the parks to undertake the needed ecosystem management under their current budgetary shortfalls. These volunteers can also be mobilized to monitor sensitive habitats and report on changes they see on trails. While this falls into the category of citizen science, and there have been legitimate questions raised about the quality of data from citizen science, there are methods of data collection and particular projects where the sheer data that can be brought in will help mitigate any issues with identification and data collection [24].

In order to keep Joshua Tree thriving, managers will need to rely on their network of stakeholders and invest in education and outreach, labor within the park, and investment in management decisions for wilderness areas. Joshua Tree has some models in place for volunteer engagement, and they work with local tribes and agencies when they are able, and it is appropriate. However, there is room for the expansion of this program in order for the park to address some visitor impact problems and land management projects. By educating local populations and visitors, the park can create a cohort of invested individuals who can be more mindful within the park’s boundaries—and who can also carry that knowledge back to their own communities. The park can send representatives into local schools to speak in science classes and educate students. They can also hold local events in the park and at the visitor center, which teach people about the local ecosystems [25, 26]. Working with local NGOs, they can hold outreach events in the communities at meetings and in conjunction with other events. By utilizing the stakeholders that are invested in the park, Joshua Tree can find protection for its lands during emergencies, generate buy-in on projects even among critics, and attract funding from partners for projects that are outside of the budget [27]. Stakeholders can also help with the education initiative, perpetuating the cycle of outreach and park stewardship. Using local NGOs to execute some of those potential education initiatives, the park can cost-share with an NGO and use the NGO volunteers to achieve some of their goals.

The science-permitting system in Joshua Tree allows for a wide variety of studies to take place (so long as they are within the bounds of the laws), but they do not require much from scientists in return. Currently, the park requests access to the findings, but they could ask for more from these scientists. The scientists could be required to hold a public lecture at the park or in the town, or they could offer guided trail hikes if they are working on plants or animals that are commonly seen. The scientists could also be asked to collaborate with the park and the local NGOs in order to develop education programs.

Using volunteers in national parks is nothing new. Since the 1969 introduction of the Volunteers in Parks Program by Congress, national parks have used volunteers in a variety of ways. Some more and some less. About half of the national parks have Friends groups that they work with, and some parks have collaborative management agreements with local NGOs in order to use volunteers at the maximum capacity. In 2016, Follman et al. published a study on volunteer programs that are co-managed by NGOs and the national parks. They focused on six parks (Acadia, Arches and Canyonlands, Cuyahoga Valley, Golden Gate, the National Mall, and Yosemite) that use this model and analyzed their success and challenges. This study showed that it is possible to build strong collaborative management with volunteers [28].

The main challenge for national parks in these situations is the challenge to their perceived autonomy. The balance between independence and collaboration for the National Park Service has to be maintained carefully, and there is ongoing work to ensure that the National Park Service is able to feel like they still have independence while the volunteers and NGOs feel that their voices are acknowledged and being taken into account. Places like Acadia have found this trade-off to be extremely profitable in terms of person hours and some focused fund-raising projects with the NGOs. Volunteer numbers and hours have gone up over time at places like Acadia. If we look at Yosemite, with its name recognition and iconic landmarks, the park is able to bring in large numbers of volunteers who pay for the pleasure of volunteering [28]. This is even more impressive given Yosemite’s remoteness, and speaks of the draw of the national parks and iconic places that remain highly valued and attractive to the public.

One thing that the study by Follman et al. [28] did not talk about is the cost of volunteers. If the volunteers in question need any equipment, a national park will need to take that into account. Radios can be lost or damaged, and props used by interpreters may also need to be replaced or more props may be needed for more volunteers. There is also the cost of time spent training the volunteers versus doing other things for staff members. All of these potential costs will need to be considered [29]. A study conducted in Arkansas looked at how much time staff members spent in training volunteers to do archeological digs; the answer was quite a bit, but the park viewed it as a sound investment because following training, the management had a volunteer force that could be called in at any time to help out with digs or archeological projects on site, thus alleviating their staff projects [30].

As can be seen in the Joshua Tree case, and in the literature on stakeholder collaborations between national parks and NGOs, it is possible to leverage volunteers to advance the mission of the parks. By building and strengthening already extant volunteer groups into networks of education and conservation volunteers, national parks can more closely fulfill their dual mandates of recreation and conservation. The budgetary shortfalls will still cause issues for national parks, but volunteer organizations and NGOs can be leveraged to mitigate some of the damage of these shortfalls. Collaborative conservation is a rising trend within conservation and the land management agencies of the Department of the Interior, but the level of integration into all the lands within those systems varies [31]. The National Park Service can leverage local and national stakeholders and NGOs in order to better reach its goals when dealing with constant budgetary shortfalls and budgetary crises.

CASE STUDY QUESTIONS

  1. Is it appropriate to use volunteers to cover budget shortfalls?

  2. What could the possible repercussions be for the national parks if volunteers were organized into the described networks to help with education and conservation?

  3. How much power should the surrounding community have in management decisions of public lands if they are directly contributing to the upkeep? Should the opinions of communities in proximity to the national parks have more weight than the opinions of more-distant communities?

  4. What kinds of methods should be used to educate people on conservation and preservation and why are they important in these landscapes?

  5. How can individual parks garner national interest in their landscapes and their needs?

  6. How can this kind of volunteer network be built within national parks in the U.S. and in other countries?

COMPETING INTERESTS

The authors have declared that no competing interests exist.

REFERENCES

REFERENCES
1.
National Park Service
.
2009
.
Making Friends: An Introduction to Building National Park Service Friends Groups
. Available: https://permanent.access.gpo.gov/lps105605/making_friends_handbook.pdf.
2.
Wilderness.net
.
Wilderness Act of 1964
; nd. Available: https://www.wilderness.net/nwps/legisact.
3.
National Park Service
.
The Organic Act of 1916. National Park Service
;
2017
. Available: https://www.nps.gov/grba/learn/management/organic-act-of-1916.htm.
4.
98th Congress
.
California Desert Protection Act of 1994
;
1984
. Available: https://www.govtrack.us/congress/bills/103/s21/text.
5.
National Park Service
.
General Management Plan
;
1995
. Available: https://ia802705.us.archive.org/9/items/generaljoshuatree00nati/generaljoshuatree00nati.pdf.
6.
Office of Budget
.
Appropriations. U.S. Department of the Interior
; nd. Available: https://www.doi.gov/budget/appropriations/.
7.
National Parks Conservation Association
.
Preserving America’s Heritage Should be a Bipartisan Issue. National Parks Conservation Association
; nd. Available: https://www.npca.org/advocacy/21-support-increased-national-park-funding.
8.
National Park Service
.
Your Fee Dollars at Work. National Park Service
;
2019
. Available: https://www.nps.gov/aboutus/fees-at-work.htm.
9.
National Park Service
.
Joshua Tree National Park Total Recreation Visitors. National Park Service
;
2019
. Available: https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Annual%20Park%20Recreation%20Visitation%20Graph%20(1904%20-%20Last%20Calendar%20Year)?Park=JOTR.
10.
Allen EB, Rao LE, Steers RJ, Bytnerowicz A, Fenn ME.
Impacts of Atmospheric Nitrogen Deposition on Vegetation and Soils in Joshua Tree National Park
. In: Webb RH, Fenstermaker LF, Heaton JS, Hughson DL, McDonald EV, Miller DM, editors.
The Mojave Desert: Ecosystem Processes and Sustainability
.
Las Vegas
:
University of Nevada Press
;
2009
. pp.
78
100
.
11.
National Park Service
.
Nonnative Species. National Park Service
;
2015
. Available: https://www.nps.gov/jotr/learn/nature/nonnativespecies.htm.
12.
Sweet LC, Green T, Heintz JGC et al.
Congruence between future distribution models and empirical data for an iconic species at Joshua Tree National Park
.
Ecosphere
.
2019
;
10
(
6
): pp.
1
17
. Available: https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2763.
13.
Meddens AJH, Kolden CA, Lutz JA et al.
Fire refugia: what are they, and why do they matter for global change?
Bioscience
.
2018
;
68
(
2
): pp.
944
954
. Available: https://academic.oup.com/bioscience/article/68/12/944/5098928.
14.
National Park Service
.
Management Policies 2006
;
2006
. Available: https://www.nps.gov/policy/MP_2006.pdf.
15.
Sellars RW.
Preserving Nature in the National Parks
.
New Haven
:
Yale University Press
;
1997
.
16.
Keele K.
Preservation and use: road building, overcrowding, and the future of our national parks
.
Tulane Environmental Law Journal
.
1998
;
11
: pp.
441
505
.
17.
Rott N.
National Parks Have a Long To-Do List but Can’t Cover the Repair Costs. NPR
.
2016
. Available: https://www.npr.org/2016/03/08/466461595/national-parks-have-a-long-to-do-list-but-cant-cover-the-repair-costs.
18.
Bendix A.
The Government Shutdown May Be Over, but the Damage to National Parks such as Joshua Tree and Yellowstone Could Be Permanent. Business Insider
.
2019
. Available: https://www.businessinsider.com/national-parks-damage-government-shutdown-2019-1.
19.
The Guardian
.
Joshua Tree National Park May Take 300 Years to Recover from Shutdown. The Guardian
.
2019
. Available: https://www.theguardian.com/environment/2019/jan/28/joshua-tree-national-park-damage-government-shutdown.
20.
Daley J.
Joshua Trees Could Take 200 to 300 Years to Recover from Shutdown Damage. Smithsonian
.
2019
. Available: https://www.smithsonianmag.com/smart-news/joshua-tree-national-park-could-take-200-300-years-recover-shutdown-180971379/.
21.
Author interview
.
Former National Park Service Employee
;
2019
.
22.
Chiu A.
‘A Travesty to this Nation’: People are Destroying Joshua Trees in Joshua Tree National Park
.
The Washington Post
.
2019
.
23.
National Park Service
.
Park Statistics
.
2016
. Available: https://www.nps.gov/jotr/learn/management/statistics.htm.
24.
Fischer H.
Tourist Centric Citizen Science in Denali National Park and Preserve. ProQuest
;
2017
.
25.
United States Department of Interior
.
Interpretation and Education Program Business Plan: Helping People Enjoy, Care About, and Care for National Parks
;
2006
. Available: https://archive.org/details/interpretationed00nati/page/10.
26.
National Council for Interpretation, Volunteers, and Education
.
Achieving Relevance in Our Second Century: A Five-Year Interdisciplinary Strategy for Interpretation, Education, and Volunteers as We Enter the Second Century of the National Park Service
.
Washington D.C.
:
National Park Service
;
2014
.
27.
Orr SK.
Environmental Policymaking and Stakeholder Collaboration
.
Boca Raton
:
Taylor & Francis
;
2014
.
28.
Follman J, Cseh M, Brudney JL.
Structures, challenges, and successes of volunteer programs co-managed by nonprofit and public organizations
.
Nonprofit Manag Leadersh
.
2016
;
26
(
4
): pp.
453
470
.
29.
McGee-Ballinger MJ.
An Assessment of the Cost of Volunteers on the Division of Interpretation in the National Park Service. ProQuest
;
2007
.
30.
Davis HA.
Training and Using Volunteers in Archeology: A Case Study from Arkansas
. Archeological Assistance Program Technical Brief No. 9. U.S. Department of the Interior, National Park Service;
1990
.
31.
Leong KM, Emmerson DP, Rebecca (Rudi) Byron.
The new governance era: implications for collaborative conservation and adaptive management in department of the interior agencies
.
Human Dimensions of Wildlife
.
2011
;
16
: pp.
236
243
. Available: https://www.nps.gov/civic/resources/Leong%20et%20al_2011_New%20 Governance%20Era.pdf.