Can existing Afro-alpine tourism promote poverty mitigation and resolve regional disparities? This article explores the significance of alpine tourism in the Mt Kenya region based on analysis of the state of the art and official statistical data along with own surveys, mapping activities, and household observations. The results show that economic benefits from mountaineering tourism in the Mt Kenya region are smaller than commonly calculated, and that low and inconsistent incomes are distributed unevenly. There are clear parallels to the critical situation in the Rwenzori Mountains in Uganda: Alpine tourism does not reduce regional income disparities and largely fails to promote sustainable development. The article also takes a closer look at the development effects of community-based tourism, drawing from the example of the Mt Kenya Guides and Porters Safari Club (GPSC), a community-based tourism organization operating from Naro Moru, at the fertile western foot of Mt Kenya. Results show that this form of tourism stabilizes the livelihoods of rural households, contributes to community welfare, and reduces the vulnerability of families. The GPSC's democratic organizational structure with elected and regularly rotating offices prevents the enrichment of only few members and ensures even distribution of benefits to all members and to the whole community. Overall, however, there is not enough tourism in the study area to initiate sustainable regional development in the foreseeable future.
Introduction and main hypothesis
For many years, tourism was considered a magic formula for promoting regional development and reducing poverty in developing countries (Ashley et al 2000; Harrison 2001; Mowforth and Munt 2003; UNWTO 2007; Telfer and Sharpley 2008). This applies in particular to the glaciated highlands of East Africa, which—in top-down processes—were all declared national parks over the past decades. The state national park authorities of Tanzania, Kenya, and Uganda attach extraordinary economic importance to Afro-alpine tourism in the scenically very attractive highest mountains of Africa: Kilimanjaro (5895 m), Mt Kenya (5199 m), and Rwenzori (5109 m) (see http://www.kws.org, http://www.tanzaniaparks.com, and http://www.uwa.or.ug).
In contrast, the present contribution and numerous other studies (eg Sinclair 1998; Hall 2007; Zhao and Richie 2007; Saarinen et al 2009, 2011; Van Der Duim et al 2012) take a critical and differentiated approach. Analyses of the effects of alpine tourism on nature reserves in tropical countries (eg Vorlaufer 1995; Banskota and Sharma 1998; Müller-Böker 2000) as well as specialized studies of Afro-alpine tourism in Kenya and Uganda (Osmaston et al 1998; Erhard 2000; Erhard and Steinicke 2006; Steinicke 2011; Steinicke and Neuburger 2012) typically show that, at best, high-mountain tourism benefits state organizations and big tour operators, whose headquarters are usually located in the respective capital. In comparison, the development impulses received by the destinations visited are insignificant: Both in the Mt Kenya region (Erhard 2000) and in the Rwenzori Mountains (Craddock Williams 1998; Steinicke 2011), alpine tourism offers only marginal and insecure monetary income. Despite this rather unfavorable balance, which is also observed in other tourist regions of the global South (Harrison 2001), in many areas the local population has tried to increase benefits to the community in organized fashion by distributing income from tourism directly to the families, avoiding external absorption of profits. This idea, termed “community-based tourism,” has been adopted in development collaboration in recent years and has been used as a regional development strategy (Scheyvens 2002; Blackstock 2005; Okazaki 2008).
From the less than voluminous state of research on community-based tourism in the high mountains of tropical Africa, as well as observations based on it, the following main hypothesis can be deduced for the Mt Kenya region: Existing Afro-alpine tourism can neither promote poverty mitigation nor resolve regional disparities. However, strategies of community-based tourism stabilize the livelihoods of rural households, even though they are inadequate measures for advancing regional development.
This work is intended as a contribution toward more detailed analysis of community-based tourism in the tropical mountains of Africa, as previously provided for East Africa by Manyara et al (2006) and Manyara and Jones (2007). The following sections explore the significance of alpine tourism in the Mt Kenya region and present the example of the Mt Kenya Guides and Porters Safari Club (GPSC), a community-based organization in Naro Moru, at the semiarid, but fertile, western foot of Mt Kenya. Naro Moru Location is characterized by scattered settlements and, according to the 2009 population census, has a total population of 21,533; Kamburaini Sublocation, which is an important starting point for climbing the volcano, has 6414 inhabitants in 1813 households (KNBS 2010). Based on the above main hypothesis, the study was designed to answer the following questions for Naro Moru and, more specifically, for Kamburaini:
How does alpine tourism in general affect the regional economy at the foot of Mt Kenya? Does tourism in the Mt Kenya region act as a driver of regional development and resolve sociospatial disparities?
Does income from community-based tourism stabilize households' livelihoods? How substantial is this income for the members of the cooperative in Naro Moru?
Which aspects of community-based tourism—eg “participation” or “empowerment”—are relevant to development and people's livelihoods? Can they promote both poverty mitigation and future prospects for the next generation?
Methods
Apart from evaluating the latest research and analyzing official statistics, this study involved the collection of primary data by a range of methods, including open, qualitative interviews and focus group discussions with guides and porters and the GPSC Steering Board; interviews with experts (District Officer, Chancellor and Chief of Location, Minister of Agriculture of Nyeri District, Chief of Sublocation, and hotel managers of Naro Moru lodges); analysis and evaluation of the GPSC's books and accounts; inspection of the visitors' books at four gates of the Mt Kenya National Park; and various mapping activities. The local population's points of view were recorded in a variety of interviews conducted by 9 students of a Master's program in Geography. The students were invited to stay with families in Naro Moru for several days and share in their daily routines, getting to know the families' livelihoods, their family structures and ties, as well as their working and living conditions. This intensive interviewing activity covered 27 households; interviews and focus group discussions with guides and porters provided deeper insights into another 48 households.
Tourism, regional development, and poverty reduction: some comments on underlying theoretical concepts
The ongoing integration of tourism in national and international strategy papers for regional development and international cooperation is based on the fact that, at the global level, tourism has been one of the most dynamic sectors of the economy over the last decades (UNWTO 2006; OECD 2010; Conrady and Buck 2011). Governments of developing countries, international development agencies, and NGOs see tourism promotion as an opportunity to initiate development processes, particularly in peripheral regions that have no other resources and potentials (Baumhackl et al 2006; Telfer and Sharpley 2008; OECD 2010). Accordingly, in the 1990s they began to apply the concept of community-based tourism, and since the 2000s a model that provides for the poor—so-called pro-poor tourism—has been practiced as a suitable future blueprint for tourism in developing countries (Hall 2007). While the former focuses on the participation and the empowerment of local communities, the latter aims at modifying economic distribution processes to improve the income of the impoverished population. However, both scholars and politicians have discussed controversial views on the potential of this type of tourism as a developing factor. Experiences gained from the implementation of these concepts in the past decades paint a contradictory picture that leaves doubts as to their effectiveness (Ashley et al 2001; Hall 2007; Okazaki 2008). Many authors question the statement postulated by the UNWTO (2007) that “tourism exchanges benefit primarily the countries of the South” (Chok et al 2007; Scheyvens 2007; Schilcher 2007). Some deplore the limited effects of tourism on ecological and socioeconomic sustainability, while others demonstrate the poverty-reducing outcomes that community-based and pro-poor tourism can have at the local level; most agree, however, that under neoliberal conditions, with uneven distribution of income and unequal power structures at the regional and international scales, tourism does not initiate any fundamental changes.
The potential of tourism per se as a poverty-reducing factor is rarely questioned; the discussion is, rather, about adequate ways of ensuring its long-term economic viability and its social and environmental sustainability. Suggestions include, for example, establishing high-priced eco-tourism or providing targeted support to small, medium, and micro-enterprises in southern Africa (Harrison 2001; Baumhackl et al 2006; Rogerson 2007; Saarinen et al 2009; Mitchell and Ashley 2010). Local initiative and bottom-up approaches are often underlined as crucial to achieving a fair and long-term effect (Zapata et al 2011).
One of the aims of this study was to review the poverty-reducing effects of community-based tourism. This was done based on the livelihoods approach, which was deemed suitable because it puts the focus on securing the daily survival of households and places the different factors of their standard of living in the foreground (Carney 2002; Lohnert and Steinbrink 2005). The approach starts from the premise that everyday management of a destitute household is based not only on monetary income from a variety of sources but also on various forms of capital, that is, social, human, natural, physical, and financial resources, which household members use in very complex, efficient, and at the same time dynamic combinations (Bohle 2001). Access to this capital, in turn, depends on parent structures and conditions, which generate inclusion and exclusion processes.
As the present study focuses on the impact of tourism at both the regional and the household levels, application of the livelihoods approach implies connecting the analyses of processes at the macro- and microlevels. At the regional level, we illuminate the effects that tourism has on the regional economy in general (job creation, regional added value, etc) and on the internal structuring of the tourism sector (corporate structure, development of upstream and downstream sectors, etc). At the community and household level, we analyze to what extent the GPSC as a community-based tourism organization contributes to community welfare, and to what degree the local population's integration in the organization ensures and stabilizes households' livelihoods.
Tourism around Mt Kenya
Since the 1990s, Kenya as a tourist destination has experienced an expansion of mass tourism. In Kenya, unlike its neighboring countries, this is connected with the successful implementation of government policies to promote a diversified offering (Job and Metzler 2003). Although the country was able to reverse the decline in visitor numbers recorded in 2007/2008, and in 2010 even reached its previous record result of nearly 1.5 million tourist arrivals (KNBS 2011), the term “mass tourism” should be used with caution and put into relation: The total number of visitors to Kenya is only slightly higher than the number of foreign tourists visiting a single Austrian valley known for its ski slopes (such as the Ziller or the Oetz valleys). Nevertheless, tourism accounts for approximately 9% of the Kenyan GDP, and more than 1 million people are (formally or informally) employed in this sector (UNWTO 2006). Despite the diversification of attractive offers to tourists, demand is still focused on coastal tourism and on game drives in the numerous national parks in savanna areas. With an average of 25,600 visitors annually (1995–2009), Mt Kenya is one of the least visited national parks in Kenya; Nakura National Park, for example, has 213,800 visitors annually (Kenya Ministry of Tourism 2011). The small number of tourists visiting Mt Kenya shows that mountaineering and hiking constitute only a tiny fraction of Kenya's tourism (Figure 1).
A socioeconomic profile of the Mt Kenya region
Situated directly at the equator, the region around Mt Kenya is a favored area for agriculture. It has fertile volcanic soils and an adequate water supply from 2 rainy seasons as well as relief precipitation (especially in the eastern and southern part) and, to a lesser extent, glacier melting. The landscape is smooth, and the temperatures are mild due to the high altitude. Already in precolonial times, Nilotic (mainly Maasai) and Bantu peoples competed for this land with its exceptionally favorable conditions; and in colonial times the British claimed the northern and western part of the area as “White Highlands” for white immigrants (Morgan 1963). In administrative terms, the Mt Kenya region can easily be delimited. Like the sectors of a pie chart, 8 districts converge at Mt Kenya's highest peak (Nelion, 5199 m). With the exception of Kyeni East Division in Nyeri North District, all 7 remaining districts are clustered mainly around the volcanic areas of Mt Kenya. The region is inhabited predominantly by Bantu peoples: Kikuyu in the west and northwest, Embu in the south, and Meru in the east and northeast. Even today, some 70% of the more than 1.7 million residents around the volcano make their living from the primary sector, which contributes approximately 80% of households' income (Kenya Ministry of State for Planning 2008; KNBS 2010). Although the poverty rate is still over 30% (Table 1), this region of Kenya is economically advantaged and therefore a popular in-migration area. The current high rates of population influx, particularly in the northern and western parts of the Mt Kenya region, have been highlighted in all surveys. On the other hand, at 3.8 the total fertility rate in the region is significantly lower than the national average (5.0). While the Kikuyu still constitute the majority of the region's population (Sim and Ronald 1979), several experts interviewed already consider that it has a multiethnic structure. The population of the divisions of Kyeni East and Timau increased by one third—from 133,600 to 178,000—in the 2 census periods from 1999 to 2009.
TABLE 1.
Poverty estimates in Kieni East Division (2008).a)
In addition to small-scale subsistence farming and minor business enterprises in the small towns, the medium- and large-scale horti- and floriculture in Timau Division has offered substantial job opportunities since the early 1990s (Schuler 2004; Figure 2). North and west of Mt Kenya is also where the most important gates to the National Park are located and where the most popular mountain climbing routes begin. Accordingly, tourist activities, guides' and porters' cooperatives, and lodges that cater to (affluent) foreign visitors are concentrated around these entry points (Figure 3). Naro Moru is located in this area as well.
The preference for the western and northern slopes is associated with distinct topographical and climatic reasons: The smooth morphology in the rain shadow offers relatively easy access to the summit of Mt Kenya. Furthermore, it should be noted that the western and northern foot slopes—the former ranchland of the Laikipian “White Highlands”—are semiarid, with less than 600 mm of annual precipitation in some parts, while the southern and eastern foot slopes benefit from sufficient precipitation and thus constitute appropriate agricultural land (Ojany and Ogendo 1988: 57, 135).
The importance of alpine tourism in the Naro Moru area
The approximately 25,600 annual visitors to the Mt Kenya National Park predominantly come from Europe (51%) and Africa (30%), followed by North America (10%). Most African visitors are Kenyans traveling in large groups; school excursions account for a substantial portion of domestic visitors. Half of the European tourists are British. A significant share is associated with the British Army base at Nanyuki, which regularly organizes trips to Mt Kenya. Other large visitor groups come from Germany, the Netherlands, France, Austria, Switzerland, and the Czech Republic. The easily accessible Naro Moru Gate to the National Park is not the one with the most entries to the summits (Figure 3). To the GPSC, however, it is of particular interest because of its proximity to the organization's office.
The results of our initial analyses show a low significance of tourism in the investigation area. In addition, it is important to consider that domestic tourism is based mainly on student excursions that are organized by official authorities and hence do not have a substantial impact on Naro Moru's economy. Even though social institutions (orphanages, hospital wards, etc) and schools are funded through revenues from the National Park, none of the schools in the vicinity focus on tourism with a view to training better qualified local personnel.
For the region as a whole, tourism has only a limited effect on socioeconomic development. This is due to the fact that a small number of large tour operators and lodges around Mt Kenya are monopolizing tourism in the region (Figure 2).
Local tour operators have established themselves in recent years, but competition has increased significantly, relativizing the economic potential for local companies. Within the tourism sector very few permanent positions are created, predominantly at the management level; many of them are filled by executives from large tourism centers such as Nairobi or Mombasa. Employment opportunities for the local population are usually temporary and low income and typically include basic service jobs at hotels or as guides and porters for multiday tours. Erhard (2000) calculated that only 2% of Naro Moru's population work in tourism, and its townscape is hardly affected by tourism.
The low importance of tourism as an economic sector is also reflected in the Nyeri North District Development Plan 2008–2012 (Kenya Ministry of State for Planning 2008). Neither in this publication nor in the Nyeri District Statistics Office (KNBS 2010) is tourism in Naro Moru an issue. It was therefore no surprise that during our interviews the District Officer and other representatives of the public administration such as the Councilor were unable to provide any information about it—apart from referring to the two international hotels of Naro Moru, the Naro Moru River Lodge and the Mountain Rock Lodge. The Naro Moru River Lodge is a large tourism establishment situated on the outskirts of the town. With 133 beds, it receives the highest numbers of visitors among local accommodators and is thus the most significant employer of local people in the tourism sector: More than 50 persons from the area work there permanently, while the smaller Mountain Rock Lodge employs between 20 and 30 local people.
The tourism sector plays an important role only for about 120 of the total 1813 households in the neighboring rural sublocation of Kamburaini. These are the guides' and porters' households (see below).
Overall, therefore, we found a type of tourism on the slopes of Mt Kenya that is evident neither spatially nor in numbers. There are even months in the rainy seasons when hardly any visitors are encountered on the individual routes. But even in July/August and December/January, when most tourist entries are recorded, only some huts along the routes notice an increase in tourist activities.
Trickle-down effects from tourism on other economic sectors are moderate. While some visitors purchase small amounts of locally grown staple foods, the 2 large hotels import most of the goods from Nairobi. Nevertheless, a small number of locally based companies in the fields of transportation, maintenance, and construction do benefit from tourist activity. In spite of these moderate benefits, the tourism industry cannot kick-start regional development in Naro Moru based on its intensity alone. Moreover, there is no evidence that visitor numbers will increase in the near future.
In terms of poverty, Naro Moru is not particularly advantaged, as a comparison with other locations around Mt Kenya and even within Kieni East Division shows (Table 1).
The GPSC as a community-based tourism organization
The development of the Mt Kenya Guides and Porters Safari Club (GPSC) can be traced back to the period of decolonization. Already in the 1960s, climbers as well as hikers in the Mt Kenya area used guiding and portage services by the local population. Guides and porters were subsequently under the management of the Naro Moru River Lodge. In 1970, however, the idea emerged to bring these service providers together in a registered and community-based organization. Approximately a dozen similar cooperatives developed around the Mt Kenya massif. Each of these guides' and porters' organizations encompasses 50 to 150 members. In 1995, the GPSC decided to purchase its own plot in the Sublocation, and from 2005 onward, with financial support from the Austrian Embassy, it built its own office, a dining hall and kitchen, a hostel, and a water tank.
The GPSC offers tours along various routes on Mt Kenya and of varying duration. Depending on the size and needs of tourist groups, the organization assembles teams of guides, porters, and cooks who are paid by days and service (in US$, exchange rate February 2011: guides 7.60, cooks 7.00, porters 5.50). A team is composed of 1 or 2 porters per tourist, as well as 1 guide and 1 cook per 5 tourists (Figure 4). As a rule, these are members of the GPSC, who are called up according to a rotation system. In order to continually improve services, new applicants must go through a 2-year probationary period before they are permanently admitted. In addition, the association strives to train its members in higher-standard services, mountain-climbing skills, and various tourism businesses.
FIGURE 4.
A group of porters resting on their way up the mountain. Each visitor of Mt Kenya National Park is provided with two porters. They carry not only the tourist's personal luggage but also sleeping bags, tents, ropes, and cooking utensils. (Photo by Ernst Steinicke).
The demand for tours is influenced above all by the seasonality of alpine tourism. The months from April to June and from October to December usually see fewer than half the number of orders registered during the high-season months from July to September and from January to March. The GPSC receives the vast majority of orders from the surrounding lodges and tourism agencies, who prefer booking with the GPSC due to the reliability of its members (Figure 5).
The GPSC's dependence on these business clients represents a major risk: From 2001 to 2010, over 80% of orders came from only 3 major tour operators, while less than 15% were individual bookings. The latter, however, earn the GPSC much higher revenues, as no commissions need to be paid to any intermediaries. For this reason, in recent years the GPSC has worked to increase the share of individual bookings by expanding and diversifying its services (tours in other national parks, lodging and provisions on its own plot); this goal was achieved in the season of 2009–2010. However, while tourism in Kenya currently shows an overall positive development, the GPSC's added value is on a downward trend. Overall, tourism in Kenya is extremely fragile due, among other things, to political instability. Reports on tribal instability and insecurity in the international mass media triggered a regressive phase prior to the riots in 2007/2008.
A steady increase in members to the current number of 150 forced the GPSC to cease accepting new applicants. The GPSC was founded as a self-ruled organization focusing on the welfare of its members and collective help among them. Its grass-roots style of decision-making fosters member participation. While a committee of 9 elected members is responsible for managing the organization, important decisions are made and elections are held at the annual general meetings. The GPSC's ambitions and organizational structure are oriented to the social well-being of its members and the community, which is fostered through a welfare fund, microcredits, support for individual members facing hardship, and various other forms of assistance. This is reflected in the organization's balance sheet, particularly in the high proportion of expenditures—usually 80–90%—paid directly to the members in the form of salaries, bonuses, and other compensations (Table 2). Furthermore, in dry periods the GPSC offers water from its tank free of charge not only to its members, but to all households of the community. The conscious rejection of a profit-oriented business model has caused the GPSC's annual expenditures to exceed revenues in some years. The high expenses for welfare services are thus preventing the organization from building up financial reserves for additional infrastructure and general maintenance work. As a result, the GPSC remains dependent on “external” support for major investments (eg from Austria).
TABLE 2.
The GPSC's expenditures by designated use, 2004/2005–2009/2010.a)
As rural households in the region largely practice small-scale subsistence agriculture, with only a very small production surplus for sale, working as guides or porters plays a prominent, but varying role in their livelihoods (Figure 6). Depending on the assets available in each household, the GPSC contributes in different ways to reducing household vulnerability: For households with small land properties (household types A and B) GPSC jobs represent one of few, or even the only source of monetary income. During the peak season, porters and guides usually have 1–3 opportunities per month to work on a multiday tour. Based on an average tour duration of 3 days and a season of about 7 months per year, this allows them to earn between US$340–480 (€250–350, February 2011 exchange rate) per year, depending on their activities. These earnings are mostly invested in improving their households' human capital, such as in education for their children and in capacity-building for adult household members. Besides the income, households have access to the large social network of the GPSC committee and can thus extend their social capital. This seems to be very important in cases of emergency, when the GPSC's welfare fund provides access to money and committee members advocate the respective household's interests with the local authorities, the public administration, and the private sector. Even families of low vulnerability (household type C) benefit from GPSC activities, as the organization's infrastructure secures water supply in times of water scarcity. Hence, by improving financial (income), human (education), physical (livestock), natural (water), and social (network) capital, the GPSC has a positive effect on households, reducing their vulnerability.FIGURE 7.
However, the social status of guides and porters in the community is relatively low, because their work is hard, and they are exposed to all weather conditions and to the risks of the mountains. Consequently, the majority of porters interviewed do not recommend their sons and daughters to become a porter or guide. Most of them stated that they want their children to be well educated and get “better” jobs and living conditions—a view that is confirmed by members of the younger generations (Figure 7).
Synthesis and conclusion
The example of the Mt Kenya region shows the multiple layers of impact that alpine tourism has in mountain areas of tropical Africa. Because of low numbers of visitors in the Mt Kenya National Park and the monopolies of a few large commercial tour operators, development endeavors at the regional level are hardly noticeable, neither with supply and service companies, nor in terms of employment effects. Nevertheless, the few available jobs in tourism are very popular, because they provide access to foreign currency and/or generous gratuities from tourists from rich countries, as well as to contacts abroad, which the local people see as a potential springboard for foreign jobs or training. The large (exclusive) hotels are the guides' and porters' organizations' most important link to clients, which leads to very one-sided relationships of dependency.
In contrast, community-based tourism, as shown by the example of the GPSC, stabilizes rural households' livelihoods and contributes to community welfare. Its particularities—a not-for-profit business model, bottom-up organization, and a democratic organizational structure with elected and regularly rotating offices—prevent the inequitable enrichment of a small group of members and ensure that benefits are evenly distributed among all members and the whole community. Due to the high reputation that the GPSC enjoys with both the large hotels and the local authorities—in July 2011 almost all representatives of public institutions followed the GPSC's invitation to attend the inaugural opening of its new buildings—it can be assumed that the concerns of the GPSC and its members are heard by the political decision makers. On the one hand, this empowerment secures uncomplicated access (in terms of bureaucracy) to the National Park as a base for tourism. Beyond that, it can contribute to more rapid emergency response, for example, in the event of a crisis, such as a drought or ethnic conflict. Overall, our results confirmed the main hypothesis underlying this research project. The results are also similar to those recently presented by Lapeyre (2011), who analyzed a tourism community–public–private partnership in a rural area in Namibia.
For rural households, employment as a guide or porter is one of the few sources of monetary income in the region; it supports the families' livelihoods. By strengthening the different forms of capital it also reduces households' vulnerability. The occupation of guide or porter is not deemed an attractive prospect for the future, however, as income from it is used primarily for educating the family's children in order to enable them to achieve higher-quality employment. In this sense, tourism may contribute to migration out of the region. At the same time, career opportunities within the tourism sector are scarce, and other segments of the economy neither provide highly qualified jobs nor respond to development impulses from tourism.
As shown by the example of the Mt Kenya region, Afro-alpine tourism as a whole provides only limited impulses to regional development. Even though community-based tourism helps to alleviate poverty and to trigger empowerment processes, the generation of equitable welfare for households and the community depends on the respective organizations' internal participatory and democratic structures. Community-based tourism alone cannot initiate sustainable regional development.
Comparing these results for the Mt Kenya region with findings on other mountain areas of tropical Africa, it can be assumed that they share similar structures and processes. Studies on tourism in the Rwenzori Mountains indicate a much less developed tourism sector, demonstrating its proportionately low impact at the local and regional levels. Although no relevant research results are available for the popular climbers' destination Kilimanjaro—recent scientific publications mostly look at ecological and climatic issues (Bloemer 2002; Bart et al 2003; Nüsser 2009; Wangui et al 2012)—the basic situation is likely to be comparable: The local population around the 3 highest mountain massifs in Africa has remained at the level of subsistence economy and does not have any attractive prospects within the region (Engelhard 1990; Erhard 2000).
Acknowledgments
The authors would like to thank the reviewers and the MRD editing team for their valuable input into this study.
