Guest Article: Combining Traditional Knowledge and Scientific Data in Forest Management

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Home » Resources » Publications » Articles » 2010 Guest Article: Combining Traditional Knowledge and Scientific Data in Forest Management

2010 Guest Article: Combining Traditional Knowledge and Scientific Data in Forest Management

Combining TEK and conventional scientific data in forest management

By Lucy Rist, R Uma Shaanker, E.J. Milner Gulland and Jaboury Ghazoul (1)

Published online 1 June 2010
| Download entire article as pdf |

Summary: Many forest communities possess considerable knowledge of the natural resources they utilise. This knowledge, by providing a source of baseline data or by filling information gaps that cannot be addressed through research, can inform scientific approaches to forest management, or provide novel management alternatives. Although the integration of TEK with conventional scientific sources of information has been well validated, there remains little attention to quantitative forms of knowledge or to identifying specific benefits and challenges arising in this integration. An emerging management challenge in a Wildlife Sanctuary in Southern India represented an ideal opportunity to assess the role of TEK in forest management. The infection of a fruit tree by a native mistletoe poses significant livelihood and biodiversity impacts. Specifically we considered the efficiency of deriving information from TEK compared to scientific field studies, the potential of TEK to provide novel solutions to a management problem, the degree to which TEK could provide quantitative information, and the biases that might be associated with information derived from TEK. TEK complemented previously gathered ecological data by providing concordant and additional information, but also contradicted some results obtained using a scientific approach. TEK also gave a longer-term perspective with regard to NTFP harvesting patterns further suggesting that the use of diverse information sources may provide a more effective approach to assessing the status of harvested resources.

Contents: Introduction | The Biligiri Rangaswamy Temple (BRT) Wildlife Sanctuary, India | Gathering TEK on mistletoe infection | Ecological knowledge of Amla harvesters | Livelihood impact of mistletoe infection | Managing the mistletoe problem | Conclusions | Footnotes | Acronyms

This article is based in part on Rist, L., R. Uma Shaanker, E. J. Milner-Gulland, and J. Ghazoul. 2010. The use of traditional ecological knowledge in forest management: an example from India. Ecology and Society 15(1): 3.


"Traditional", "Indigenous", or "Local" ecological knowledge (TEK, IEK and LEK) have all been used to refer to sources of knowledge about species, ecosystems or practices held by people whose lives are closely linked to, or dependent upon, their natural environment. Although the term TEK is most commonly used, implying the development of knowledge over a longer timescale, communities with a more recent association with an area or resource still may often possess a detailed acquired knowledge or understanding of the ecology and management of that area and the resources they utilise. As such, knowledge recently acquired by local communities can be just as important as "traditional" information generated over a longer timescale (2).

The increasing use of TEK in conservation and natural resource assessment is the result of three factors: The demonstrated efficiency of TEK; where TEK corresponds well to scientific data it can be a more efficient method of acquiring information replacing costly ecological research with less resource intensive social science approaches. The additionality of TEK; the interaction of knowledge holders with landscapes at much larger scales and over longer periods of time than are possible in standard scientific investigation permits TEK to provide information at novel temporal and spatial scales. Finally, the use of TEK can be linked to a broader trend towards increasing use of participatory approaches in resource management and conservation, programs that garner the support of local people through their participation being recognized as having a greater chance of acceptability and therefore long-term sustainability.

While the integration and use of TEK in resource management and associated scientific research is increasing there remains little discussion of cases where TEK and conventional scientific studies appear contradictory, and few studies have focused on identifying specific strengths and inadequacies of TEK, including the use of more quantitative information. This article reports on a study which considered the validity and additionality of TEK in terms of quantitative as well as qualitative management relevant information in the context of a specific management problem; the infection of an NTFP of livelihood importance by a native mistletoe.

The Biligiri Rangaswamy Temple (BRT) Wildlife Sanctuary, India

The Biligiri Rangaswamy Temple (BRT) Wildlife Sanctuary is located in the state of Karnataka, India on the easternmost ridge of the Western Ghats. The 540 km² protected area faces multiple threats including fire, encroachment from villages on the borders of the Sanctuary, and the spread of invasive species. The area is home to the indigenous Soliga community, as well as a smaller non-indigenous population. Traditionally semi-nomadic, the Soligas were settled into villages and allotted land for agriculture when the area was declared a Wildlife Sanctuary in 1976. In addition to wage labour and agriculture, these communities supplement their livelihoods through collection of a wide variety of NTFPs, including fruits, honey, and lichens. Soliga dependence on NTFPs for household income is extensive, ranging from about 30% in the forest margin to over 60% in interior villages (3). In particular the fruit of Amla (Phyllanthus emblica L. and Phyllanthus indofischeri Bennet), contributes over 10% of the cash income of the Soligas, yet infection by a native mistletoe species (Taxillus tomentosus) is currently reducing fruit production and leading to significant tree mortality with livelihood as well as wider ecological implications (4).

Gathering TEK on mistletoe infection

TEK was gathered through interviews with 50 Amla harvesters from across the Sanctuary. By including individuals knowledgeable about all portions of the geographic area relevant to the resource, the data represent a good picture of Soliga knowledge about Amla in BRT. All respondents were interviewed in the local language by a local research assistant trained to conduct the surveys. Before agreeing to participate respondents were informed of the purpose of the study; to better understand the nature and cause of the perceived threat to Amla from mistletoe infection and to see how scientific research and the communities knowledge and experience could be combined in tackling this threat. Interviews consisted of a mix of specific and open-ended questions in two categories; the first focused on natural history observations, the second was specific to management. Questions in the natural history category targeted information on host tree associations, mistletoe distribution, optimal growing conditions, phenology, pollination and dispersal. Questions associated with management pertained to more specific information on the impact of mistletoe infection on the growth, productivity and mortality of Amla, the variation in susceptibility between the two Amla species and the comparative productivity levels of infected and uninfected trees.

The answers to each question were compared to available ecological data derived from field studies and previously published research. In this evaluation, accuracy referred only to whether the answer matched the available ecological data. By assessing the correspondence between the two information sources, including validity and additionality, areas where TEK may be most useful in resource assessment were identified. Current and historical harvesting trends as perceived by resource users were investigated and compared with official harvest records over a fifteen year period (1990-2005) in order to more fully understand the impact of mistletoe infection on Amla, including investigating explanations for a discrepancy between sustainability as indicated by harvesting records and local perspectives on resource status.

Ecological knowledge of Amla harvesters

A. Mistletoe distribution and host species

All respondents were familiar with the mistletoe, referred to locally as 'Bili Uppilu' or 'Antu Uppilu'. In fact many respondents identified five or more mistletoe species present in BRT, their descriptions matching results from mistletoe diversity surveys. In terms of qualitative information, differences in infection characteristics and impacts between the two species, the results from TEK and scientific approaches were well matched. For other aspects, such as secondary mistletoe host species, or the dispersal agents of mistletoe seeds, TEK provided additional information not revealed by scientific studies. In particular, harvesters identified more than double the number of secondary host species as found in forest surveys, identifying several rare host associations that were unlikely to have been detected with the ecological sampling scheme used. While more extensive sampling is required to conclusively establish the relative accuracy of TEK and field surveys in this respect, these findings suggest that TEK may be particularly valuable as a source of information on rare events (i.e. rare host-mistletoe associations), that may require considerable fieldwork to identify.

Quantitative measures similarly revealed both concordance and divergence. Harvester and scientific assessments of infection prevalence in the Amla population were closely matched, with no significant difference between the two estimates (t = 2.16, df = 48.1, NS). In contrast, estimates of the magnitude of infection impact on productivity differed considerably; a standard scientific approach had previously revealed a 44% decline in fruit production. This was compared with a mean value from TEK of 68%. An explanation for this significant difference is not apparent. It is often assumed that a result generated from a scientific study is more accurate, however we hesitate to make this judgment. As the host species example illustrates, scientific studies have their own inaccuracies, in that particular case a limited sampling scheme. The scientific estimate for impact on productivity came from one study carried out as part of a four year research project, in comparison to the TEK estimate, provided by 50 harvesters who have collectively gathered significantly more hours of observation. In consideration of this we should give careful consideration to our bias in assuming which is more accurate.

B. Spread of mistletoe infection

The use of TEK extended current knowledge regarding mistletoe bird dispersers; harvesters identified eight species compared to the two currently reported in scientific studies. However, some discrepancies were also identified. In addition to being asked to list the species they had observed eating mistletoe fruits, harvesters were also asked about the mechanisms by which mistletoes spread. Both questions were aimed at establishing the same information (i.e. identifying dispersal agents of mistletoe seeds) yet elicited quite different responses. Several mammals, including squirrels and rats were identified by harvesters as fruit consumers. While dispersal of T. tomentosus by anything other than birds has not previously been documented in the literature, mammalian dispersal has been documented for mistletoes elsewhere, and due to the lack of previous studies on dispersal of this particular species the possibility that mammals also play a role in the dispersal cannot be discounted. Wind was cited as a dispersal mechanism by 20% of harvesters. Efficient dispersal of mistletoe seed requires not only the ingestion and transport of the sticky seeds but their active placement on the branches of an appropriate host. Although dispersal by mammals is feasible, wind dispersal is highly unlikely. These results also highlighted the importance of framing questions carefully; when asked directly what they thought was responsible for spreading the mistletoes, the answers were less reliable. Observational information from harvesters appeared to be more accurate than that based on their understanding or interpretation of processes or mechanisms. However, this has not been the case in other systems where harvesters have elucidated complex biological or ecological processes (5). Indeed, two harvesters also identified a novel mechanism of infection spread and accumulation in infected trees, the growth of epicortical roots (6). The presence of these roots was supported by observations made during ecological studies.

C. Efficiency of data collection

TEK provided information more efficiently (in terms of data collection effort expended by scientists in this study) and of equivalent accuracy than conventional ecological studies. For example, TEK closely matched field data on mistletoe phenology, specifically the timing of flowering and fruiting. Phenological studies took place over 12 months requiring approximately 24 hours of fieldwork per month, involving two field workers, a total of 288 hours for the entire study. Social science methods gathering information through interviews took considerably less time and resources; 47 interviews were conducted by one individual taking a total of approximately 70.5 hours (1.5 hours per interview).

Livelihood impact of mistletoe infection

In the context of NTFP collection there has been speculation that the Amla population may be in decline as a consequence of excessive and destructive methods of harvesting and forest fire. Harvesters in contrast consider that mistletoe infection is the main threat to Amla, quoting a population decline of around 50% in the last 10 to 20 years as a direct result of infection. In our interviews they reported a mean decline of 88.5 kg per day and 15 days in the duration of harvesting, representing a substantial reduction in annual collection, approximately 80% on average per individual.

The Forest Department keeps annual records of the Amla harvest. Over the fifteen-year period considered, these highlighted significant temporal variability in fruit production but did not appear to show evidence of a decline in yield. While these records have been used as evidence for sustainable harvesting this study raises serious concerns for the viability of Amla. Combining harvester knowledge on current and historical collection patterns with official harvest records suggests that an increase in the number of individuals participating in the Amla harvest may mask a declining resource base, with significant implications for harvester livelihoods. Monitoring based on quantitative biological variables alone is insufficient and additional information on harvesting effort is required, such aspects of harvester behaviour may contain important information on resource status and can be a useful gauge for monitoring the sustainable collection of NTFPs.

Managing the mistletoe problem

We asked harvesters about approaches that could be implemented in a formal management program to respond to the mistletoe problem. Suggestions included controlled burning and chemical treatment but the majority cited the chopping of infected branches as the most suitable response. Hand removal, the method currently advocated by the Forest Department, was mentioned but dismissed due to it being physically difficult to implement and not a permanent method of removal (the mistletoe rapidly re-grows from tissue remaining with the host branch). These explanations matched the findings of an experimental assessment of both management techniques; branch chopping was superior on multiple criteria (4).

Harvesters were asked about the relationships between fire, Amla and the current mistletoe problem. All said that prior to a ban by the Forest Department a ground level fire occurred annually in the forest. Harvesters said that while trees were not damaged by this burning regime it did act to regulate the mistletoe population. However, few indicated that they felt this was the best current solution to the mistletoe problem, the high prevalence of the invasive shrub Lantana camara in the forest and its intense flammability meaning that fire might cause significant damage.


In general, data from ecological studies and TEK were closely matched. Harvesters provided accurate information on infection characteristics including primary host species, mistletoe distribution and mistletoe phenology. TEK provided estimates of quantitative variables of management significance such as prevalence of infection in considerably less time and at less expense. However, there were also some discrepancies between the two, most notably in terms of secondary host species and dispersal mechanisms. This investigation showed that TEK can be useful as a source of quantitative information. It also demonstrates where such information may be most useful, and additionally, in the context of this study, where it may be misleading or inaccurate.

This study into the use of TEK in forest management highlights the need to focus less on issues of “correctness” with regard to the use of TEK and to place more emphasis on what it can add to resource management when used in combination with standard scientific approaches. The limitations and biases inherent in both TEK and scientific studies should be recognised within the particular management context in which they are used. Indeed, a significant benefit of combining the use of TEK and conventional scientific data in management may be that the two sources of information may be used to check against the other providing more robust conclusion upon which management can be based. TEK can fill information gaps and highlight promising directions for management and further research, but must be used in full recognition of its limitations. It can be expanded upon through scientific methods (whose limitations must also be recognised), in addition to local experimentation based on traditional management practices. Such approaches, adaptively developing and testing our understanding with the participation of local people and resource users, and designing resource management solutions that are compatible with local ethics may be more culturally appropriate and therefore more likely to be accepted and successful, and additionally, may be a more time efficient and cost effective approach to resource management and conservation.

Management at BRT faces two crucial challenges; firstly, despite evidence indicating the serious nature of the mistletoe threat to Amla, current monitoring programmes have not highlighted the scale of decline in the population; and secondly, disagreements over approaches to managing mistletoe infection remain unaddressed and unresolved. TEK has provided information relevant to both these. TEK is a source of novel information that could be used for the formulation of a management response to mistletoe infection. We suggest these results provide evidence to support a greater role for local communities in the current management of the BRT sanctuary.


  1. Lucy Rist is a Postdoctoral Research Fellow at the Department of Ecology and Environmental Science, Umeå University, Sweden, R Uma Shaanker is Professor of Crop Physiology at the University of Agricultural Sciences in Bangalore, India. E.J Milner Gulland is Professor of Conservation Science at Imperial College, London. Jaboury Ghazoul is Professor of Ecosystem Management at ETH Zürich, Switzerland.
  2. Mallory, M. L., H. G. Gilchrist, A. J. Fontaine, and J. A. Akearok. 2003. Local ecological knowledge of Ivory Gull declines in Arctic Canada. Arctic 56(3): 293-298.
  3. See Uma Shaanker, R., K. Ganeshaiah, B. Chinnappa Reddy, V. Krishnan, R. Rajagoplan, J. Aravind, A. Kumar, G. Vanraj, and D. Rao. 2002. Enhancing the role of forest fruits in sustaining livelihoods of forest margin communities. Technical report submitted to Department for International Development, London, UK and Hegde, R., S. Suryaprakash, L. Achoth, and K.S. Bawa. 1996. Extraction of non-timber forest products in the forests of Biligiri Rangan Hills, India. 1. Contribution to rural income. Economic Botany 50(3): 243-251.
  4. Rist, L., R. Uma Shaanker, E. J. Milner-Gulland, and J. Ghazoul. 2008b. Managing mistletoes: the value of local practices for a non-timber forest resource. Forest Ecology and Management 255 (5-6): 1684-1691.
  5. See Donovan, D. G., and R. K. Puri. 2004. Learning from traditional knowledge of non-timber forest products: Penan Benalui and the autecology of Aquilaria in Indonesian Borneo. Ecology and Society 9(3): 3.
  6. Epicortical roots are external roots arising from the mistletoe stem that traverse the host bark and eventually establish new connections with the host tree.



BRT: The Biligiri Rangaswamy Temple Wildlife Sanctuary 
df: Degrees of freedom
NS: Not significant
NTFP: Non-timber forest product
TEK: Traditional ecological knowledge

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