Previous article Next article ARTICLE Year : 2004  |  Volume : 2  |  Issue : 2  |  Page : 235-250 Assessing Ecological Sustainability of Non-Timber Forest Produce Extraction: The Indian Scenario Ghazala Shahabuddin1, Soumya Prasad2 1 Environmental Studies Group, Council for Social Development, 53, Lodi Estate, New Delhi 110 003., India 2 Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012., India Correspondence Address: Ghazala Shahabuddin Environmental Studies Group, Council for Social Development, 53, Lodi Estate, New Delhi 110 003. India Source of Support: None, Conflict of Interest: None Check Date of Web Publication 18-Jul-2009

Abstract

Non-timber forest products (NTFP) are extensively extracted from Indian forests, and their role in rural and forest economies is immense. However, the long-term ecological sustainability of NTFP extraction with respect to resource populations, dependent animal species and ecosystem functioning has remained largely unexamined. In this article NTFP research undertaken in India is reviewed in an attempt to understand issues related to ecological sustainability. There is a glaring scarcity of systematic research on ecological aspects of NTFP extraction in India. From the few available studies, it appears that species differ in their responses to harvest depending on the plant part extracted, natural history attributes and harvesting techniques. However, regeneration and population densities of some NTFP species are reported to be adversely affected by extraction. Such adverse effects, though, cannot be attributed to NTFP harvests alone, but rather to a com­bination of harvests, damaging harvesting practices and accompanying anthro­pogenic disturbances such as fire, grazing and fuel wood collection. There is little information on the long-term indirect effects of NTFP extraction on dependent animal species. The available literature also indicates a disturbing trend of eco­system simplification due to intensive forest use, including extraction of NTFP, which may gradually lead to the weeding out of vulnerable plant species from Indian forests. Much more research is required before it can be clearly understood to what extent and in what ways livelihoods based on NTFP can be compatible with biodiversity conservation.

Introduction

). In India the role of NTFP in forest con­servation has gained additional impetus lately with increasing emphasis on participatory models of forest conservation, such as joint forest management and community-based conservation, in which NTFP extraction constitutes an attractive economic incentive for local people (for recent reviews, see Kothari et al. 1997; Ravindranath et al. 2000).

In the current climate of increasing support for extractivism as a tool for bio­diversity conservation, the long-term ecological sustainability of such extractivism has unfortunately remained obscure and unstudied. However, recently there has been increasing concern globally about the impacts of NTFP extraction on popu­lations subject to extraction, on resource users other than humans, as well as on ecosystem functioning (Bawa 1992; Bhatnagar 2002; Lambert 1998; Shankar et al. 1996, 1998; Ticktin 2004; Vasquez and Gentry 1989). In India, too, popu­lations of commercially extracted species are reported to be declining in many parts of the country, and reports of adverse ecological impacts of NTFP harvest are becoming increasingly common (Mohan Ram, personal communication; Murali et al. 1996; Negi 2003; Shankar et al. 1998). Clearly, a rethinking of the linkages between forest produce extraction and ecological sustainability in India's forests is long overdue.

Sustainable resource use can be defined as the maintenance of an undiminished flow of benefits from the resource to its users over time (Lele 1994). However, this deceptively simple definition is complicated by the fact that the various differ­ent benefits provided by any forest resource to its different users are generally not simultaneously maximised (ibid.). Homma (1992) proposed that if sustainability of NTFP extraction is to be achieved from the point of view of all resource users, then social, economic and political structures at local, regional and national levels need to be managed in such a way that NTFP extraction is lucrative over time, yields social improvement for its participants, and does not compromise ecological and agronomic equilibrium. In purely ecological terms, extraction can be con­sidered sustainable if the harvest has no long-term deleterious effect on the reproduction and regeneration of populations being harvested in comparison to equivalent non-harvested natural populations, and if the harvest has no discernable adverse effect on other species in the community, or on ecosystem structure or functioning (Hall and Bawa 1993). We confine ourselves to discussing the ecological aspects of sustainability only, while recognising that forest management policy has to equally critically take into account political, economic and cultural contexts of forest use. In this article we review NTFP research done in India in an attempt to answer the following specific question: What are the possible impacts of NTFP extraction on target populations, on dependent animal species, and on ecosystem structure and function? Since the literature on hunting in India is still very limited, we confine ourselves to NTFP of plant origin.

Impacts of NTFP Extraction on Resource Populations

NTFP harvests may affect plant populations at two different levels: first, at the level of the individual, on vital rates such as growth and reproductive capacity; and, second, at the level of the population, which manifests in its demographic structure and long-term dynamics. The direct effects of intensive forest produce collection may include decline in productivity, density and/or regeneration of the targeted plant species, depending on the part of the plant that is utilised (Cunningham 2001; Peters 1994; see [Figure 1] for a synopsis of the possible biological effects of NTFP harvest).

An important approach to studying impacts of NTFP harvest on natural popu­lations has been to examine whether there is sufficient regeneration of the resource population, particularly for tree species (Hall and Bawa 1993). The underlying rationale is that a continuously regenerating population will ensure that the resource is not depleted and there will be a continuous flow of benefits to people dependent on these resources over time. However, assigning cause and effect between re­source use and observed regeneration is not straightforward for several reasons. First, it is difficult to locate control (unharvested) populations that differ from treatment (harvested) populations in every respect except for intensity of harvest. This is because anthropogenic factors such as grazing, fuel wood use, fire man­agement, hunting, timber cutting and NTFP extraction are often correlated.

For example, in tropical dry forests in India, low-intensity fires that are lit for the purpose of making NTFP collection easier cause damage to seedlings and saplings of several tree species (Saha 2002). Lack of regeneration could also be due to other environmental stresses, such as herbivore damage, presence of invasive plant species, pathogens and resource deficiencies, whose effects may be enhanced under certain anthropogenic disturbances. Therefore, an observed lack of adequate regeneration of a target population could be due to one or a combination of these factors. Second, defining how much regeneration constitutes 'adequate' regener­ation is not straightforward due to differences in vital rates and population para­meters across species and across ecosystems.

The most commonly adopted approaches to overcome these practical difficulties in designing studies to assess impacts of NTFP harvest on target populations have been, first, to compare regeneration and girth-class distributions (proportion of individuals belonging to different size or age classes) of NTFP species at sites subject to different harvesting intensities. Typically, an inverse J-shaped curve that shows very high proportion of seedlings and saplings in relation to adult trees is considered to represent a healthy regenerating population. Sharply declining densities of individuals in successively larger size (or age) classes produces the inverse J-shaped girth-class distribution for a species. A second step in this ap­proach is to compare girth-class distributions of harvested NTFP and non-NTFP species within a given forest area. However, in this case there may be the danger of glossing over important differences in natural history attributes of different species. Another approach is to use population modelling to assess impacts of various extraction pressures on population structure using empirically determined estimates of growth and reproductive rates. There have also been attempts to quantify genetic variability and reproductive fitness of populations subject to different intensities of harvest. Use of such measures offers insights into impacts of harvests on processes such as pollination, dispersal and gene flow within popu­lations, and thus relate to long-term evolutionary consequences of harvest.

A large number of studies on the linkages between NTFP harvest and resource regeneration have emerged from long-term research being carried out at a single site in south India-the Biligiri Rangaswamy Temple (BRT) wildlife sanctuary (Murali et al. 1996; Shankar et al. 1998; Sinha 2000). Shorter-term studies have also been carried out at sites in central (Koliyal 1997; Pant 2003) and north-west (Prasad 2001) India. All these studies have focused partly or exclusively on Phyl­lanthus emblica. Some studies at BRT have also examined Phyllanthus indo­fischeri, Strychnos potatorum, Terminalia bellerica and T. chebula (Shaankar et al. 2001; Shankar et al. 1998; Sinha 2000), and Koliyal (1997) has studied Madhuca latifolia and Buchanania lanzan in central India. A recently concluded study, possibly the most comprehensive so far, has investigated the population status of Garcinia gummi-gutta in differently managed sites in wet evergreen forests of the Western Ghats (Rai 2003; see also Rai and Uhl in this issue). For all other NTFP such as Shorea robusta, Diospyros melanoxylon, Boswellia serrata, Sterculia urens and Cordyceps sinensis, literature that exists on demographic aspects of harvested populations is largely anecdotal in nature (see [Table 1] for details of uses and parts extracted of these and other plant species mentioned in this article).

Many studies have found lowered regeneration of NTFP species at heavily harvested sites when compared to areas subject to lower harvesting pressures (Koliyal 1997; Murali et al. 1996; Pant 2003; Shaankar et al. 2001; Shankar et al. 1998; see [Figure 2] for a hypothetical example). Some of these studies also report that regeneration of NTFP species was lower than that of non-NTFP species at heavily harvested sites (Murali et al. 1996; Shankar et al. 1998). The latter two studies also report overall low numbers of saplings in the smallest size class all over the BRT sanctuary, whether in high-intensity or low-intensity harvest sites, indicating extremely low rates of regeneration of not just NTFP, but several other tree species. For Phyllanthus emblica, the most widely studied species across the country, a number of studies have reported low seedling and sapling densities in intensively harvested areas compared to areas subject to lower extraction pressures (Koliyal 1997; Murali et al. 1996; Padmini et al. 2001; Prasad 2001; Shankar et al. 1998). In sharp contrast to these studies, Rai (2003) did not find any statistical difference in ratios of G. gummi-gutta seedling densities (<0.5 m in height, the smallest size class) to large trees (having greater than 20 cm girth at breast height [gbh]) between low-intensity and high-intensity harvest. There may, however, in fact be some differences in densities of saplings (>0.5 m height, but <40 cm gbh) between low-intensity and high-intensity harvesting sites when standardised with respect to tree density (see [Figure 6] in Rai and Uhl in this issue).

Results from all of the above studies should be thought of as indicating broad trends rather than yielding conclusive results, given typically low sample sizes. The lack of control sites (where there has been no harvest), especially in compar­able physiographic conditions, necessitates comparisons between many sites across a gradient of harvest histories and intensities. Use of distal and proximal sites as surrogates for low-intensity and high-intensity harvesting situations respectively (as in Murali et al. 1996; Shaankar et al. 2001; Shankar et al. 1998) is also problem­atic, given that foraging radii and routes may change from year to year. Addition­ally, some studies mentioned (for example, Rai 2003) intensive harvesting had begun only a few years before the data was collected. Impacts of harvesting on regeneration of the resource species may not be detected in such a short period. As indicated by results from a recent study across twenty-three sites in the Amazon (Peres et al. 2003), both history and intensity of harvests are major determinants of population structure of harvested species. Peres et al. (ibid.) found that juvenile recruitment was severely affected in populations subject to persistent harvests.

Another approach to assess impacts of harvests and other anthropogenic factors on resource populations is the use of matrix models used to model population dynamics (Boot and Gullison 1995). The validity of such models is critically dependent on accurate field estimation of plant growth rates and reproductive rates, which are likely to be very variable both spatially and temporally, neces­sitating extensive sampling in space and time (Freese 1997; Peters 1994). In India there have been few attempts to establish limits on harvests using such population modelling approaches. Shankar et al. (1996) have tried to define sustainable yield for P. emblica extraction at the BRT sanctuary, but their attempt was inadequate due to lack of sufficient data. And Murali and Srinivasulu (2000) modelled effects of different rates of extraction on plant densities of some medicinally important herb species at the BRT sanctuary: Sida cordifolia, Sida rhombifolia, Dioscorea bulbifera, Asparagus racemosus, Decalepis hamiltonii and Hemidesmus indicus, using an empirical approach (see [Table 1] for uses of these plant species). In most cases, more than 25 per cent extraction was found to be detrimental to local plant populations. The most comprehensive work on these lines was carried out by Rai (2003) who quantified growth rates and reproductive capacity of G. gummi-gutta trees. For this population, even very high levels of harvest of seed (up to 90 per cent) were demonstrated not to affect the future structure of the resource population (ibid.). However, a sharp decline in tree populations was projected beyond 90 per cent seed harvest. As model parameters can vary substantially between years depending on climatic conditions and other ecological factors, model projections as in Rai (ibid.), and Murali and Srinivasulu (2000) should be treated as tentative. Further work, taking into account temporal and spatial variability, is required to substantiate findings such as these.

Genetic studies offer opportunities to examine long-term evolutionary impli­cations of chronic harvesting on resource populations. The few genetic studies of NTFP species from India are largely suggestive and are constrained by being limited to a few loci. Shaanker et al. (2001) found no significant differences be­tween populations of Terminalia bellerica and T. chebula for genetic diversity parameters across a disturbance gradient (control, moderate and high) at the BRT, but there were some appreciable differences between the disturbance levels as seen with principal component analyses (PCA) for both species. This suggests that extraction may have altered the genetic structure of these two plant populations. For P. emblica, Padmini et al. (2001) found that extraction of fruits may lead to loss of reproductive fitness and genetic differentiation of populations across dis­turbance gradients at two sites (BRT and Mudumalai wildlife sanctuary). While several seed and seedling features were significantly affected by disturbance at both sites, genetic diversity decreased with increasing disturbance only at one of the sites (Mudumalai). Populations close to human settlements tended to cluster together and were separated from those farther away within each site and on pooling samples (ibid.). This suggests that P. emblica populations are affected nearly similarly by anthropogenic pressures at these two sites.

Many studies have indicated that damaging harvesting methods affect resource populations equally or more than the actual removal of plant parts. Sinha (2000) found that fire had a larger effect on population growth rates than actual harvests for Phyllanthus emblica and P. indofischeri at the BRT. Traditional non-destructive methods are increasingly being replaced by less time-consuming and less labour­intensive methods in India, both due to increase in demand for NTFP and the open-access nature of forest land (see Rai 2003). Removal or damage of reproduc­tive individuals may have the greatest impact on population growth in slow­growing tree species. Sinha and Bawa (2002) found that populations of P. emblica and P. indofischeri were more sensitive to destructive harvesting (for example, lopping of branches) than to fruit harvest per se. They found that such harvesting techniques reduced fruit production the following year for these species. Rai (2003) similarly found that population growth was more sensitive to adult tree mortality caused by lopping than to harvest of G. gummi-gutta fruit in wet evergreen forests of the Western Ghats. Koliyal (1997) and Pant (2003) have also reported destructive harvesting practices in deciduous forests of central India with branches, and sometimes whole trees, being cut down to obtain fruits.

Effects of extraction on local population densities of extracted plant species, particularly tree species, may be expected to manifest only in the long term. How­ever, in several cases, adverse effects have already been observed on adult popu­lations of plants. Shankar et al. (1998) found that NTFP species exhibited greater densities and basal areas in sites subjected to relatively lower extraction pressures compared to heavily extracted sites. Anecdotal information exists from other areas, though this needs to be substantiated by systematically collected long-term data. Several commercially important species are likely to become extinct in Sheopur forest division in Madhya Pradesh, including Boswellia serrata, Sterculia urens and Phyllanthus emblica (Bhattacharya and Hayat 2003). Several species of rhododendrons in Sikkim are thought to be under threat of extinction from over­exploitation for fuel wood and incense manufacture (Singh et al. 2003). Similarly, surveys of Cordyceps sinensis in Uttaranchal, a composite fungus larva organism formed by the parasitisation of a moth caterpillar by fungus, indicate that the population of this species in Uttaranchal is visibly declining even on an annual basis due to the pressure from human extraction (Negi 2003). Interviews with vil­lage groups managing central Indian forests in Gadchiroli, Maharashtra, indicate that there is a general perception of population decline in Sterculia urens due to over-exploitation of gum (Shahabuddin, personal observation). Rapidly declining densities of Acacia catechu, a species whose bark has been harvested intensively for katha manufacture during the last few decades, has been reported from the Aravalli hills of north-western India (Mohan Ram, personal communication). Availability of medicinal plants such as Chlorophytum tuberosum and Rauwolfia serpentina is also under serious threat in central Indian forests due to over­exploitation (Boaz, undated).

Impacts on Other Species

The removal of a given plant product from a forest may also adversely affect dependent animal populations, the effects of which could then reverberate through forest ecosystems as many of the affected species could be significant pollinators or fruit dispersers (see Terborgh 1998). With ever-increasing habitat loss and frag­mentation, NTFP resources could currently be of critical importance to the survival of threatened populations of animals, particularly those sourced from keystone species (ibid.). The degree of specialisation of animal species with respect to specific plant products would determine, to a large extent, the degree of impact. In the long term, it is possible that large-scale export of nutrients from these forests in the form of various plant parts may be unsustainable, though these effects are rarely studied (Salafsky et al. 1992). Though it is well-recognised that humans share forest resources with a large number of other species, there have been few studies to date looking at sustainability of NTFP extraction from the point of view of other resource users (but see Bakuneeta et al. 1995; Chapman and Onderdonk 1998; Lambert 1998; Prasad 2001). Could extractive activities become unsustainable to these other resource users?

Extraction of forest produce might degrade the quality of the habitat of dependent species due to reduction in quantity of available food. Prasad (2001) investigated impacts of fruit harvest on the frugivore community of P. emblica at Rajaji National Park in north-west India. At Rajaji, P. emblica fruits were con-sumed by four mammals-langur (Semnopithecus entellus), chital (Axis axis), barking deer (Muntiacus muntjac) and Indian gerbil (Tatera indica). For these frugivores, extraction of fruits by people represented loss of a food resource (ibid.). Current knowledge of the ecology of certain frugivorous species suggests that loss of food resources due to NTFP extraction might limit wildlife populations. For ex­ample, Green and Minkowski (1977) observed that in the shola forests of the Western Ghats, harvesting of the scarce Artocarpus spp. fruits deprived the lion­tailed macaque (Macaca silenus) of one of its most important year-round foods. Kumar (1985), from a year-long study of the lion-tailed macaque, found that removal of selected products like fruits of Artocarpus hirsuta, Syzygium cumini and cane could drastically alter food resources of this species, even if done rarely.

In particular, extractive uses have the potential to limit food resources of animals like the brown palm civet (Paradoxurus jerdoni), which are heavily dependent on seasonal and spatially patchy resources such as fruits (Herrera 1982; van Schaik et al. 1993). Fruit resources constitute a large fraction of the diet of the brown palm civet (a mammal endemic to the Western Ghats) in all seasons (Mudappa 2001). For the thirty-four plant food items identified to species level in the diet of the brown palm civet by Mudappa (ibid.), we found that fourteen (29 per cent) had uses listed for fruit or seeds, twenty-three (68 per cent) had parts other than fruit or seed used by people and only eight (23 per cent) had no uses listed in the volumes of Wealth of India (Anon 1976). It remains to be examined whether such human uses have actually limited population sizes and distribution of the brown palm civet or other dependent animal species.

Rai (2003), however, has noted that there may not necessarily be competition between frugivores of G. gummi-gutta and fruit harvesters if fruits are picked off the ground after natural fall rather than directly harvested from trees. Most recorded frugivores are arboreal and likely to consume pulp from fruits on the tree itself while only the hard, uneaten rind, which is left on the ground, has market value. Nonetheless, while traditionally G. gummi-gutta was harvested by picking the rind off the ground, large-scale commercial extraction mostly involves collection of fruits from trees (Balachandra Hegde, personal communication).

Of special concern within protected areas in India is the association of illegal hunting with legitimate forest-based activities such as NTFP extraction (A.J.T. Johnsingh, personal communication; Madhusudan and Karanth 2000; Prasad 2001). It has often been argued that permitting NTFP extraction in protected areas might lead to such collateral damage, which could take a heavy toll on wildlife within these areas. Thus, in areas designated for wildlife protection, permitting NTFP harvests might have other far-reaching consequences, even for species that are not dependent on the resource directly, in ways that have yet to be understood.

Effects on Community Composition and Ecosystem Functioning

Declining densities and regeneration of extracted species can lead to substantial changes in structure of forest communities. Such changes might be reflected in a shift in the composition of plant communities as well as a lowering of diversity, biomass and net primary productivity of these ecosystems. A growing body of literature based on studies conducted in various parts of India indicates that in­tensive human use of forests is leading to a gradual change in forest ecosystems characterised by species impoverishment and, consequently, ecosystem simplifica­tion. Species exploited intensively for their parts, those vulnerable to fire, invasive species, grazing and repeated lopping, those dispersed exclusively by animals, or those germinating in specific micro-climatic and soil conditions, appear to be at risk and may be getting 'weeded' out from intensively exploited forests (Daniels et al. 1995; Ganeshaiah et al. 1998).

Though there are no studies that have focused exclusively on impacts of NTFP harvest on community composition or ecosystem function, extractive uses have been listed as one of the anthropogenic pressures that has brought about these changes (ibid.). As an example, it has been observed that deciduous forests are slowly being taken over by increasing density of scrub forest species at the BRT sanctuary (ibid.). Similarly, it has been documented that evergreen and deciduous species in wet evergreen forests of the Western Ghats are giving way to species that have features adapted to arid climates (Daniels et al. 1995). Ganeshaiah et al. (1998) and Pant (2003) found that long-term anthropogenic pressures had led to animal-dispersed species becoming less common, and wind-dispersed plant species increasing in density, resulting in a shift in phyto-sociological attributes of plant communities. In the Shorea robusta-dominated forests of south-western West Bengal, it is feared by many that intensive extraction of biomass over the last two centuries may have converted originally multi-species Shorea-dominated forests to almost mono-cultural stands (T.K. Mishra, personal communication; Palit 1999; Shahabuddin 2002). Throughout this region, regeneration of Shorea robusta is very low and is regarded as a serious problem today. Quantitative studies have shown that areas subject to lower levels of extractive pressures were more diverse in terms of tree species and had lower densities of S. robusta in proportion to other species (Das et al. 2000; Lal et al. 1993; Mishra and Banerjee 1997; Ramnarayan et al., undated). As mentioned earlier in this article, where overall poor rates of regeneration of several tree species have been recorded through extensive sampling at the landscape level at BRT (Murali et al. 1996; Shankar et al. 1998; see [Figure 2]). These observations portend a highly species-poor scenario in the future for regions subject to intensive harvests. Only long-term vegetation studies in intensively used forests can help quantify some of these changes thought to be underway in forest ecosystems on a large scale.

Conclusion

The current review indicates that there is scant, mostly anecdotal, information on the ecological sustainability of extraction of the hundreds of NTFP in India, ob­tained from various plants. Only a few species of trees have been studied quanti­tatively and over adequate spatial and temporal scales for discerning possible harvesting impacts; there are next to no studies on herbs and shrubs.

The available literature indicates that species and populations differ in their responses to harvesting, as would be expected. The degree to which plant popu­lations are adversely affected by harvesting depends on natural history attributes of plant species, harvesting techniques adopted, the extent of extraction and the plant part used (see also Rai 2003; Ticktin 2004). However, it is also clear that several NTFP plant species in India may be subject to unsustainable use as indicated by lowering of adult population densities and reduced regeneration ability, even inside protected areas. In many cases, it is likely that forest use practices that typically accompany harvesting activities, such as grazing, fires and tree cutting, and accompanying micro-climatic and soil changes, may have as much or greater impact on regeneration of resource populations as does actual removal of plant parts. Certainly, taken together, harvesting of plant parts and accompanying forest use practices are having an overall detrimental effect on plant regeneration and densities of studied NTFP species in many sites. There is also evidence from the published literature that NTFP extraction and accompanying forest use practices may be leading to overall forest ecosystem simplification due to selective extinc­tions of plant species in the long term.

Recent ecological studies on frugivorous and other animal species indicate that NTFP extraction may represent a significant loss of food resource and changes in habitat structure for dependent animal species. A near absence of long-term quantitative studies makes it difficult to link population declines of dependent animal species, if any, with NTFP harvests. Nonetheless, from current knowledge of plant-animal linkages in tropical forest ecosystems, we infer that collection of plant parts is particularly likely to have an impact on specialist animal species.

The current review thus indicates that in the process of planning for forest use, we need to not only recognise potential impacts of NTFP extraction on target species, but also on other resource users of the same resource, as well as on eco­system processes. A more rigorous information base on important NTFP species throughout the country needs to be built up before extractive uses or interventions can be planned in Indian forests, especially in areas designated for wildlife protection. Much more research is required before it can be clearly understood to what extent and in what ways livelihoods based on NTFP can be compatible with biodiversity conservation.

Acknowledgements: We thank M.D. Madhusudan, Nitin Rai, Renee Borges and Sharad Lele for discussions and information that led to this article; Nitin Rai and Divya Mudappa for providing valuable information from their ongoing research for this review; Ashish David, Bharath Sundaram, Joseph Vattakavan, Raman Kumar and Roopali Raghavan for help with the pre­paration of this manuscript. SP wishes to thank the Wildlife Institute of India for providing facilities that supported this work. GS is grateful to Winrock International-India for their financial support for a research project that inspired this review.^[67]

 

References

1.	Anon. (1972), Wildlife (Protection) Act. New Delhi: Ministry of Environments and Forests.
2.	(1976), The Wealth of India (Vols I-XI). New Delhi: Council for Scientific and Industrial Research.
3.	(1980), Forest Conservation Act. New Delhi: Ministry of Environments and Forests.
4.	Bakuneeta, C., K. Johnson, R. Plumpire and V. Reynolds (1995), 'Human Use of Tree Species Whose Seeds are Dispersed by Chimpanzees in the Budongo Forest, Uganda', African Journal of Ecology, 33: 276-78.
5.	Bawa, K.S. (1992), 'The Riches of Tropical Forests: Non-Timber Products', Trends in Ecology and Evolution, 7: 361-63.
6.	Bhatnagar, P. (2002), 'Conservation and Trade of Medicinal Herbs: A Study of Safed Musli (Chloro­phytum spp.) in Madhya Pradesh', Sustainable Forestry, 7: 11-14.
7.	Bhattacharya, P. and S.F. Hayat (2003), 'Sustainable NTFP Management for Livelihood and Income Generation of Tribal Communities: A Case from Madhya Pradesh, India', in Proceedings of Workshop on Policies, Management, Utilization and Conservation of Non-Timber Forest Products (NTFP) in the South Asia Region. Bangalore: Ashoka Trust for Research in Ecology and the Environment.
8.	Boaz, A. (undated), Medicinal Plants: A Resource under Threat-Some Policy Issues for Con­servation. Bhopal: Madhya Pradesh Forest Department.
9.	Boot, R.G.A. and R.E. Gullison (1995), 'Approaches to Developing Sustainable Extraction Systems for Tropical Forest Products', Ecological Applications, 5: 896-903.
10.	Chapman, C.A. and D. Onderdonk (1998), 'Forests without Primates, Primate/Plant Co-dependency', American Journal of Primatology, 45: 127-41.
11.	Chopra, K. (1997), 'The Valuation and Pricing of Non-Timber Forest Products: Conceptual Issues and a Case Study from India', in F. Smith (ed.), Environmental Sustainability: Practical Global Implications, pp. 107-40. Florida: St Lucie Press.
12.	Cunningham, A.B. (2001), Applied Ethnobotany: People, Wild Plant Use and Conservation. London: Earthscan Publications.
13.	Daniels, R.J.R., M. Gadgil and N.V. Joshi (1995), 'Impact of Human Extraction on Tropical Humid Forests in the Western Ghats in Uttara Kannada, South India', Journal of Applied Ecology, 32: 866-74.
14.	Das, N., S.C. Mahapatra and R.N. Chattopadhyay (2000), 'Joint Forest Management in Five Villages of Nayagram Range, Midnapore, West Bengal', in N.H. Ravindranath, K.S.Murali and K.C.Malhotra (eds), Joint Forest Management: An Ecological and Institutional Assessment, pp. 265-78. New Delhi: Oxford and IBH.
15.	Fearnside, P. (1989), 'Extractive Reserves in Brazilian Amazon', Bioscience, 39: 387-93.
16.	Freese, C.H. (1997), 'The "Use it or Lose it" Debate: Issues of a Conservation Paradox', in C.H. Freese (ed.), Harvesting Wild Species: Implications for Biodiversity Conservation, pp. 1-48. Baltimore: Johns Hopkins University Press.
17.	Ganeshaiah, K.N., R.U. Shaankar, K.S. Murali, U. Shankar and K.S. Bawa (1998), 'Extraction of Non-Timber Forest Products in the Forests of Biligiri Rangan Hills, India, 5: Influence of Dis­persal Mode on Species Response to Anthropogenic Pressures', Economic Botany, 52: 316-19.
18.	Green, S. and K. Minkowski (1977), 'The Lion-tailed Macaque and its South Indian Rainforest Habitat', in Prince Rainier III and G.H Bough (eds), Primate Conservation, pp. 290-338. New York: Primate Conservation Academic Press.
19.	Hall, P. and K.S. Bawa (1993), 'Methods to Assess the Impact of NTFP on Plant Populations', Economic Botany, 47: 234-47.
20.	Herrera, C.M. (1982), 'Seasonal Variation in the Quality of Fruits and Diffuse Coevolution between Plants and Avian Dispersers', Ecology, 63: 773-85.
21.	Homma, A.K.O. (1992), 'The Dynamics of Extraction in Amazonia: A Historical Perspective', Advances in Economic Botany, 9: 23-32.
22.	Koliyal, A. (1997), 'Extraction of Non-Timber Forest Produce from Selected Tree Species in Betul Forest Division and its Impact on the Population Structure of these Species', unpublished M.Sc. thesis. Dehradun: Wildlife Institute of India.
23.	Kothari, A., S. Suri and N. Singh (1995), 'Conservation in India: A New Direction', Economic and Political Weekly, 30: 2755-66.
24.	Kothari, A., F. Vania, P. Das, K. Christopher and S. Jha (1997), Building Bridges for Conservation: Towards Joint Management of Protected Areas in India. New Delhi: Indian Institute of Public Administration.
25.	Kumar, A. (1985), 'Patterns of Extinction in India, Sri Lanka and Elsewhere in South East Asia: Implications for Lion-tailed Macaque Wildlife Management and the Indian Conservation System', in P.G. Heltne (ed.), Lion-tailed Macaque: Status and Conservation, pp. 65-90. New York: R. Liss.
26.	Lal, J.B., V.K. Bahuguna, Hilaluddin and S. Hussain (1993), 'Ecological Studies of Sal Forests in Bankura North Forest Division, West Bengal', Van Vigyan, 32: 15-22.
27.	Lambert, D. (1998), 'Primate Frugivory in Kibale National Park, Uganda, and its Implications for Human Use of Forest Resources', African Journal of Ecology, 36: 234-40.
28.	Lele, S. (1994), 'Sustainable Use of Biomass Resources: A Note on Definitions, Criteria, and Practical Applications', Energy for Sustainable Development, 1: 42-46.
29.	Madhusudan, M. D. and K.U. Karanth (2000), 'Hunting for an Answer: Is Local Hunting Compatible with Wildlife Conservation in India', in J.G. Robinson and E.L. Bennet (eds), Hunting for Sustainability in Tropical Forests, pp. 339-55. New York: Columbia University Press.
30.	Malhotra, K.C., D. Deb, M. Dutta, T.S. Vasulu, G. Yadav and M. Adhikari (1992), Role of Non­ Timber Forest Produce in Village Economy. Kolkata: IBRAD.
31.	Mishra, T.K. and S.K. Banerjee (1997), 'An Ecological Reconnaissance of Lateritic Forest of South­west Bengal', Advances in Forestry Research in India, 16: 5-43.
32.	Mudappa, D. (2001), 'Ecology of the Brown Palm Civet Paradoxurus jerdoni in the Tropical Rain­ forests of the Western Ghats, India', unpublished Ph.D. thesis. Coimbatore: Bharathiar University.
33.	Murali, K.S. and Srinivasulu (2000), 'Use of Medicinal Plants in a Sustainable Way: Assessment of Impact due to Extraction', in A. Arunachalam and M.L. Khan (eds), Sustainable Management of Forests: India, pp. 169-85. Dehradun: International Book Distributors.
34.	Murali, K.S., R.U. Shaankar, U. Shankar, K.N. Ganeshaiah and K.S. Bawa (1996), 'Extraction of Non-Timber Forest Produce in the Forests of Biligiri Rangan Hills, India, 2: Impact of NTFP Extraction on Regeneration, Population Structure and Species Composition', Economic Botany, 50: 252-69.
35.	Negi, C.S. (2003), 'Yar Tsa Gumba', Down to Earth, 15 October: 49-51.
36.	Nepstad, D.C. and S. Schwartzman (1992), Non-Timber Products from Tropical Forests: Evaluation a Conservation and Development Strategy. New York: New York Botanical Garden.
37.	Nepstad, D.C., F. Brown, L. Luz, A. Alechandra and V. Viana (1992), 'Biotic Impoverishment of Amazonian Forests by Rubber Tappers, Loggers & Cattle Ranchers', Advances in Economic Botany, 9: 1-14.
38.	Padmini, S., M.N. Rao, K.N. Ganeshaiah and R.U. Shaanker (2001), 'Genetic Diversity of Phyl­lanthus emblica in Tropical Forests of South India: Impact of Anthropogenic Pressures', Journal Tropical Forest Science, 13: 297-310.
39.	Palit, S. (1999), 'Bonds of Amity: Joint Forest Management in West Bengal has Come to Stay', Wasteland News, 14: 21-27.
40.	Panayotou, T. and P.S. Ashton (1992), Not by Timber Alone: Economics and Ecology for Sustaining Tropical Forests. Washington, DC: Island Press.
41.	Pant, A. (2003), 'Ecological Analysis of the Satpura Conservation Area Landscape through Stratified Field Sampling and Remotely Sensed Data', Proceedings of Map 2003. New Delhi: Department of Science and Technology, http://www.gisdevelopment.net/application/environment/ conservation/mi0321.htm.
42.	Peres, C.A., C. Baider, P.A. Zuidema, L.H.O. Wadt, K.A. Kainer, D.A.P. Gomes-Silva, R.P. Salomao, L.L. Simoes, E.R.N. Franciosi, F.C. Valverde, R. Gribel, G.H. Shepard Jr., M. Kanashiro, Coventry, D.W. Yu, A.R. Watkinson and R.P. Freckleton (2003), 'Demographic Threats to the Sustainability of Brazil Nut Exploitation', Science, 302: 2112-14.
43.	Peters, C.M. (1994), Sustainable Harvest of Non-Timber Plant Resources in Tropical Moist Forest: An Ecological Primer. Washington, DC: World Wildlife Fund.
44.	Peters, C.M., A.H. Gentry and R.O. Mendelsohn (1989), 'Valuation of an Amazonian Rainforest', Nature, 339: 655-56.
45.	Pinedo-Vasquez, M., D. Zarin and P. Jipp (1990), 'Use Values of Tree Species in a Communal Forest Reserve in Northeast Peru', Conservation Biology, 4: 405-16.
46.	(1992), 'Community Forest and Lake Reserves in the Peruvian Amazon: A Local Alternative for Sustainable Use of Tropical Forests', Advances in Economic Botany, 9: 79-86.
47.	Prasad, S. (2001), 'Fruit Removal, Seed Dispersal and Demography of Emblica officinalis at Rajaji National Park, Uttaranchal', unpublished M.Sc. thesis, Dehradun: Wildlife Institute of India.
48.	Rai, N.D. (2003), 'Human Use, Reproductive Ecology, and Life History of Garcinia gummi-gutta, a Non-Timber Forest Product, in the Western Ghats, India', unpublished Ph.D. thesis. University Park: Pennsylvania State University.
49.	Ramnarayan, K., N.P. Melkania, P. Bhattacharya and S.B. Roy (undated), 'Forest Floor Sweeping: A Case Study from West Bengal Forest Protection Committee', Technical Paper No.7. Kolkata: Indian Institute of Bio-social Research and Development.
50.	Ravindranath, N.H., K.S. Murali and K.C. Malhotra (2000), Joint Forest Management: An Ecological and Institutional Assessment. New Delhi: Oxford and IBH.
51.	Saha, S. (2002), 'Anthropogenic Fire Regime in a Deciduous Forest of Central India', Current Science, 82: 101-4.
52.	Salafsky, N., B.L. Dugelby and J.W. Terborgh (1992), 'Can Extractive Reserves Save the Rain Forest? An Ecological and Socioeconomic Comparison of Non-Timber Forest Product Extraction Systems in Peten, Gautemala, and West Kalimantan, Indonesia', Conservation Biology, 7: 39-52.
53.	Schwartzman, S. (1992), 'Land Distribution and the Social Costs of Frontier Development in Brazil: Social and Historical Context of Extractive Reserves', Advances in Economic Botany, 9: 51-66.
54.	Shaankar, R.U., K.N. Ganeshaiah and M.N. Rao (2001), 'Genetic Diversity of Medicinal Plant Species in Deciduous Forest of South India: Impact of Harvesting and Other Anthropogenic Pressures', Journal of Plant Biology, 28: 91-97.
55.	Shahabuddin, G. (2002), 'Biodiversity in Commerce: An Assessment of Current Knowledge on the Biological Sustainability of Forest Product Extraction in West Bengal and Proposed Research Strategies', technical report. Delhi: Winrock International.
56.	Shankar, U., K.S. Murali, R.U. Shaanker, K.N. Ganeshaiah and K.S. Bawa (1996), 'Extraction of NTFP in the Forests of Biligiri Rangan Hills, India, 3: Productivity, Extraction and Prospects of Sustainable Harvest of Amla Phyllanthus emblica (Euphorbiaceae)', Economic Botany, 50: 270-79.
57.	(1998), 'Extraction of Non-Timber Forest Products in the Forests of Biligiri Rangan Hills, India, 4: Impact on Floristic Diversity and Population Structure in a Thorn Scrub Forest', Eco­nomic Botany, 52: 302-15.
58.	Sheil, D. and S. Wunder (2002), 'The Value of Tropical Forest to Local Communities: Complications, Caveats, and Cautions', Conservation Ecology, 6: 9, http://www.consecol.org/vol6/iss2/art9.
59.	Singh, K.K., S. Kumar, L.K. Rai and A.P. Krishna (2003), 'Rhododendron Conservation in the Sikkim Himalaya', Current Science, 85: 602-6.
60.	Sinha, A. (2000), 'Sustainability of Fruit Extraction from Two Non-Timber Forest Product Tree Species, Phyllanthus emblica and P. indofischeri, in the Forests of South India', unpublished Ph.D. thesis. Boston: University of Massachusetts.
61.	Sinha, A. and K.S. Bawa (2002), 'Harvesting Techniques, Hemiparasites and Fruit Production in Two Non-Timber Forest Tree Species in South India', Forest Ecology and Management, 168: 289-300.
62.	Terborgh, J.W. (1986), 'Keystone Resources in the Tropical Forest', in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity, pp. 330-44. Boston: Sinauer Associates.
63.	(1998), 'Wildlife in Managed Tropical Forests: A Neotropical Perspective', in. A.E. Lugo and C. Lowe (eds), Tropical Forests: Management and Ecology, pp. 331-42. New York: Springer­ Verlag.
64.	Tewari, D.D. (1994), 'Development and Sustaining Non-Timber Products: Policy Issues & Concerns with Special Reference to India', Journal of World Forest Resource Management, 7: 151-78.
65.	Ticktin, T. (2004), 'The Ecological Implications of Harvesting Non-Timber Forest Products', Journal of Applied Ecology, 41: 11-21.
66.	van Schaik, C.P., J.W. Terborgh and S.J. Wright (1993), 'The Phenology of Tropical Forests: Adaptive Significance and Consequences for Primary Consumers', Annual Review of Ecology Systematics, 24: 353-77.
67.	Vasquez, R. and A.H. Gentry (1989), 'Use and Misuse of Forest Harvested Fruits in Iquitos Area', Conservation Biology, 3: 350-61.

Figures

  [Figure 1], [Figure 2]
 
 

Tables

  [Table 1]

	Previous article Next article