Untapped Potential: Agricultural Social Networks as the future of Karst Science Communication in Phong Nha-Kẻ Bàng National Park, Vietnam

Elizabeth J. Willenbrink, Center for Human GeoEnvironmental Studies, Department of Geography and Geology, Western Kentucky University
Leslie A. North, Center for Human GeoEnvironmental Studies, Department of Geography and Geology, Western Kentucky University
Vu Thi Minh Nguyet, Institute of Geological Sciences, Vietnam Academy of Science and Technology
DOI: 10.21690/foge/2016.61.3f


Hang Son Doong, the world’s largest documented cave, is more than just a record-breaking karst phenomena. For the resident’s in Phong Nha-Ke Bang National Park (PN-KB), Son Doong and the Park’s 300 other discovered caves are a representation of the beauty and uniqueness of the region’s karst landscape (Figure 1). Karst landscapes are known for their unique cave systems and spectacular surface features. Formed in carbonate rock, such as limestone, karst landscapes are characterized by bedrock that is dissolved easily by water, resulting in the creation of conduits, caves, and surface features such as sinkholes and karst towers. These landscapes are also home to unique endemic cave and surface species (Ford and Williams 2007). Despite their fantastic and unique features, karst landscapes are highly vulnerable to anthropogenic degradation such as water contamination, surface erosion, and deforestation (Ford and Williams 2007; Fleury 2009). While PN-KB residents are eager to speak about the benefits of karst-centric tourism and show caves in their area, many lack fundamental knowledge about the formation of PN-KB’s geology and, even more importantly, its extreme fragility to human development, especially agriculture.

Figure 1: The welcome sign to Phong Nha-Ke Bang National Park perched high upon a karst tower.

PN-KB is a UNESCO designated World Heritage Site located in central Vietnam. Measuring 350,000 hectares, the Park is a protected area covering one of the largest karst massifs in Asia (Tranh 2012) (Figure 2). The Park is known for its dense jungle, abundant biodiversity, massive cave systems, and soaring karst towers, some of which measure up to 1,000 meters (Hübner et al. 2014). Less frequently noted, however, is the Park’s large local population. Nearly 65,000 people live within the PN-KB buffer zone, the majority of which practice small-scale subsistence and commercial agriculture (Tranh 2012; Willenbrink 2018) (Figure 3).

Figure 2: Karst towers of Phong Nha-Ke Bang National Park. These towers are located near the Management Board and are traversed by the Son River, the main surface stream of the Park.
Figure 3: Map of Phong Nha-Ke Bang National Park. The Park is located in Central Vietnam and is divided between a core protected area and surrounding buffer zone.

The negative impacts that human and agricultural development have on karst landscapes is widely discussed in modern literature (Ford and Williams 2007; Coxon 2011). In the karst region of PN-KB, where nearly 80% of the population practices agriculture, there is increased soil tillage, soil erosion, and water contamination (Tranh 2012; North et al. 2016; Willenbrink 2018). These effects harm the abundant, yet fragile, karst ecosystem and flora of PN-KB and also pose a threat to the humans living on the landscape. Generally, deforestation and agriculture on karst landscapes results in a loss of soil, decreased retention of nutrients increased in soil runoff and unwanted sediments and contaminants entering already vulnerable water supplies (Ford and Williams 2007; Coxon 2011). Karst soils are known for being highly erodible and rocky; thus, with consistent tillage, cropping, and harvesting, karst soils become even vulnerable to sustained erosion and nutrient loss. Increased erosion on karst terrain also increases surface runoff (Drew 1982; Coxon 2011). Any substances or materials on the karst surface is highly likely to runoff into nearby sinkholes or leach through the thin soils; through this process, human waste, animal waste, urban runoff, and agricultural chemicals can all enter both surface and subsurface water supplies and cause contamination (White 1998; Ford and Williams 2007; Fleury 2009; Coxon 2011; Ciglič et al. 2012). Additionally, due to its high porosity and permeability, water that travels through limestone bedrock in karst regions is not filtered of an any contaminants or sediments contained within that water remain (White 1998; Palmer 2007). Moreover, water that enters groundwater supplies can travel through subsurface caves and conduits and reemerge on the surface in either springs, rivers, or lakes (White 1998). Therefore, surface contaminants entering karst water supplies can persist for long periods of time and can travel long distances (Ford and Williams 2007; Chen and Bi 2011).

Surface and subsurface water flow is abundant in PN-KB, but a complete understanding of subsurface hydrology has not yet been achieved (North et al. 2016; Willenbrink 2018). Therefore, while it is known that water resources in PN-KB are being contaminated by urban and agricultural contaminants, there is little understanding of the geographic extent of this contamination (Jiang et al. 2009; Chen and Bi 2011). As characteristic of the subsurface groundwater networks of karst landscapes it is, however, likely that pollution threatens the entire human population in PN-KB, as well as the Park’s flora and fauna; thus, PN-KB residents, and any agricultural communities living atop karst landscapes, are both causing degradation to karst resources and feeling the negative consequences of this degradation (Naughton-Treves et al. 2006; Willenbrink 2018) (Figure 4).

Figure 4: Houses built around a sinkhole. Waste from the homes or agriculture surrounding the sinkhole can easily be picked up by rain, washed into the sinkhole, and enter groundwater.

Farms in PN-KB are diverse and widespread. Families grow a range of crops such as guava, bananas, cassava, peppercorns, sweet potatoes, chilis, paper trees, rubber trees, and rice (Figures 5 and 6). While crops on individual farms vary, some crops are more likely to cause harm to the local landscape than others. Paper trees, rubber trees, and rice, though highly profitable, can cause significant damage to the soils in which they are grown (Fox et al. 2014). Cultivation of these crops is an economic staple throughout Southeast Asia, but their growth on karst landscapes is especially important to understand.

Figure 5: Farms in PN-KB National Park are widespread and extend to the base of karst towers.
Figure 6: Peppercorn and banana trees are commonly found on farms in PN-KB National Park. While bananas are grown for subsistence and market sales, peppercorn is grown for export.

Paper and rubber trees are commonly cultivated by farmers who then sell their harvest as a way to earn a living (Kerkvliet 2006; Fox et al. 2014). These two crops generate more income than traditional produce; however, paper and rubber trees require extensive use of fertilizers and pesticides, as well as intense cultivation practices that leaves soils stripped, thin, and erodible after harvest (Verheye 2010). During their growth period, paper and rubber trees utilize any and all accessible soil nutrients, thus requiring the application of additional fertilizers. During harvest, soils are excessively tilled and plant roots are removed, leaving soils unconsolidated (Fox et al. 2014). Since soils atop karst landscapes are already thin and rocky, with slow regeneration rates, when crops such as rubber or paper trees are grown in karst regions the rate of soil erosion is further increased and the use, and subsequent runoff, of fertilizers has amplified effects on local water resources, including groundwater (Drew 1982; Coxon 2011). Further, because of the high profitability of rubber and paper trees, fields of these crops are rarely left fallow and are typically replanted in the next planting season (Verheye 2010), creating a cycle that erodes soils, produces inferior crops, requires more and more fertilizers, and ultimately increasingly threatens human health and wellbeing.

In addition to growing paper and rubber, residents of PN-KB also practice wet-rice cultivation. River plains throughout the Park are planted with rice, which receives all of its irrigation with seasonal rains and river floods. While soil erosion from wet rice cultivation is naturally mitigated through yearly floods, the consistent application of fertilizers and pesticides to rice crops can be detrimental to the PN-KB’s karst resources and human population (Bouman and Tuong 2001). Nearly all of Park residents who grow rice report using agricultural chemicals on their crops. This practice is particularly dangerous because introducing agrochemicals to an already flooded rice paddy diminishes the transport time between surface and water, reducing any chance of natural filtration, and increasing concentrations of these chemicals in water resources (Bouman and Tuong 2001). Excessive agrochemicals in water resources can lead to nutrient overloads that cause harmful algal blooms, threaten river biodiversity, and contaminate drinking water (Urich 1993; Bombaradeniya and Amarasinghe 2003; Coxon 2011).

An additional agricultural threat to the karst resources of PN-KB comes from the practice of animal husbandry (Figure 7). Throughout PN-KB, families often raise cows and water buffalo, both of which are used to help harvest rice and other crops. Especially when animals are located in rice paddies, animal waste is being directly introduced to water resources. E. Coli and other harmful water contaminants can significantly harm human health and cause widespread disease.

Figure 7: Most farming families in PN-KB own cows or water buffalo to help with farm tasks. These animals typically reside in resident yards or agricultural fields.

Atop karst landscapes, nutrient overloads and waste contamination in surface water can then make their way into subsurface aquifers, conduits, and caves. If contaminants enter caves, they can significantly alter cave water chemistry (Drew 1982; Bombaradeniya and Amarasinghe 2003). Species living within caves or depending on cave resources for survival are then threatened because of water contamination. Specifically in PN-KB, water resources are highly connected and transverse the buffer zone-core zone boundary, meaning that any human or agricultural contaminants in the buffer zone can easily enter the core area and threaten protected species that live within or depend upon cave resources for survival (North et al. 2016; Willenbrink 2018).

In addition to threatened biodiversity, human populations living on top of karst landscapes are also at risk from agricultural water contamination. The majority of residents in PN-KB get their drinking water from ground or surface streams (Willenbrink 2018). Only a small portion of the Park population, roughly 10%, have consistent, affordable access to bottled water and even fewer residents, about 1%, have access to water filtration systems (Willenbrink 2018) (Figure 8). As a result, the vast majority of Park residents rely on unfiltered water for drinking and are consistently exposed to chemicals and contaminants that threaten their health.

Figure 8: Water filtration system used by a ranger station in PN-KB National Park. Water filtration systems are extremely rare among park residents.

Managing the Karst Terrain of PN-KB

The current management of PN-KB is confined to forest and biodiversity protection, with little recognition of the Park’s karst resources or agricultural communities. While some water quality tests are conducted, Park management reports that tested parameters are confined and the frequency of these tests are periodic, at best. Therefore, human population, agriculture, and karst resources within PN-KB remain minimally regulated, placing both human and environmental health at risk (Naughton-Treves et al. 2005; Wickle and Le 2013; Willenbrink 2018). Because removing all intense agricultural activity from the region is not feasible and deregulating agriculture is detrimental to land and human health, a balance between agriculture and landscape protection must be reached (Naughton-Treves et al. 2005; North et al. 2016; Willenbrink 2018).

While agriculture-karst interactions are well studied, the cultural and human aspect of these interactions is often overlooked in modern literature. As is the case in PN-KB, many farmers in karst areas are solely reliant on agriculture for their income and sustenance. This poses a unique challenge – how can the geologically and biologically fragile karst landscapes be protected while also sustaining livelihoods for poor and vulnerable human populations?

Many karst protected areas are sparsely populated or located in an area where residents are socially and economically privileged (Lynagh and Urich 2002). In these regions, detrimental activities, such as agriculture, can be eliminated and the karst landscape can be protected; however, this is not an option for highly rural or poor farming populations living in karst protected areas (Urich et al. 2001). For the majority of farming families, farming is necessary; daily meals are based upon what is harvested and, what little crops are left over, are sold at markets to provide a living.

New frameworks must be developed in this area for education, capacity building, and resiliency among vulnerable populations living on karst landscapes. The vast majority of farmers within PN-KB do not know or understand karst landscapes. Only those individuals in charge of park management have access to many resources where this information can be obtained and communicated among the park population.

While access to karst science is limited, residents of PN-KB value caves for their economic and cultural value. Many caves in the area host tours, which bring tourism and money to the region. Additionally, two caves, Eight Lady Cave and Tien Son, hold significant cultural value to local populations (Figure 9); Eight Lady Cave is located on the region’s main road and is home to a temple honoring eight women trapped and killed from American bombs during the Vietnam War (Vu Thi Minh Nguyet, personal communication). This cave and temple is a common stop among locals who light incense and pay tribute to the deceased (personal observation); thus, cave and karst protection in PN-KB is both natural and cultural preservation. In addition to spreading information about karst science, park officials and rangers can encourage cave and karst landscape protection by evoking local dedication towards cultural preservation.

Figure 9: Temple located outside of Tien Son Cave (photo courtesy of Jason Polk).

By utilizing both formal and informal communication networks, the comprehension of karst landscape vulnerabilities can be increased. Most importantly, educational and capacity-building programs can be used to highlight the short term and long term benefits of karst consciousness – less land erosion, less landslides, protection against common floods, and healthier soils. Altogether, these result in more plentiful crops, less need for artificial fertilizers and pesticides, and a general increase in income. Programs such as these can set precedent for increased understanding of karst landscapes around the world, particularly among vulnerable agricultural communities.

The communication networks at play in PN-KB include residents, park rangers, and park officials. Informal communication networks between Park residents are highly developed and extremely successful, extending to every park resident (Willenbrink 2018). These informal communication networks, both in PN-KB and in other agricultural communities around the world, possess untapped potential for the spread of important scientific information regarding karst landscapes (Demíyürek 2010). Conversely, formal communications between scientists, policymakers and their constituency are often lacking or unsuccessful. Worldwide, knowledge and research on karst landscapes is largely concentrated among scientists and researchers (Watson et al. 1997); however, the people in closest contact with karst resources—those living and working on karst land—have minimal access to this information. Within PN-KB, residents and rangers have little understanding of karst landscapes because their access to information on the subject is virtually nonexistent (Willenbrink 2018). Formal connections between scientists and policymakers must occur to get more people involved in the protection of vulnerable karst landscapes. Moreover, understanding the success of informal communication networks, they must then become the key to spreading important karst science to broad populations ways that are understandable, accessible, and easily implemented.

By simply bridging the communication gap between residents, rangers, and officials through the use of formal trainings and informal communication networks, information regarding PN-KB policy, agricultural practices, and karst landscapes can be heard and understood by the broad Park population. A greater understanding of agriculture and karst landscapes can then lead to increased protection of karst resources, decreased use of harmful agricultural practices, and a greater collaboration between PN-KB management officials and PN-KB residents. Achievement of these recommendations will lead to simplified, successful park management through increased engagement of park residents with park goals. In making local populations part of a solution as opposed to separate from a solution, PN-KB management can effectively make each park resident a purveyor of protection for the Park’s unique karst, forest, and biodiversity resources. This concept is true worldwide; the greater the involvement of local populations in the protection of local resources, the more likely it is that protection will be successful (Urich 1989; Urich et al. 2001; Hoag et al. 2006). In short, the use of informal communication networks to encourage the preservation and protection of karst landscapes is increasingly important throughout the world as a growing population and expanding agricultural need has forced humans to live in close contact with karst landscapes (Coxon 2011).

Local tourism is an additional avenue towards karst education for local residents. A previous study published in FOCUS by North et al. (2014) suggests that informal communication of karst science through tourism is a valuable and meaningful way to encourage understanding. When individuals better understand a landscape, they are more likely to protect it. Therefore, it would be valuable for residents of PN-KB to be offered discounted or free tours in local show caves in which they can be educated on the need for cave and karst protection. Because residents understand the economic value of caves, as well as their significant cultural value, education through tourism is a currently unused tool.

Once residents better understand the caves and karst of PN-KB, they must be encouraged to take active roles in the communication of karst science and policy. Through formal trainings and informal communication, karst science can be made relatable and protective behaviors can be made simple, manageable, and incremental. Collaboration between scientists, policymakers, and citizens will create a network of accountability and communication, thus increasing the broad understanding of karst landscape vulnerabilities and subsequent protection. The interactions between humans, agriculture, and karst landscapes are inevitable but the nature of these interactions is open to positive change. By incorporating informal communication into current techniques for karst land management, future protection of karst landscapes will be an accessible option for all individuals working and living on karst landscapes.


The authors would like to thank the Cave Conservancy Foundation, Western Kentucky University, and the Alive Center for their financial support of this project. Additional thanks to the Institute of Geological Science at the Vietnam Academy of Science and the Phong Nha-Kẻ Bàng Management Board for their logistical support. Lastly, huge thanks to all community members who gave their time and thoughts for this project.


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