Abstract
Harvesting wild plants for non-timber forest products (NTFPs) can be ecologically sustainable–without long-term consequences to the dynamics of targeted and associated species–but it may not be economically satisfying because it fails to provide enough revenues for local people over time. In several cases, the same species can be harvested for NTFP and also logged for timber. Three decades of studies on the sustainability of NTFP harvest for local people’s livelihood have failed to successfully integrate these socio-economic and ecological factors. We apply optimal control theory to investigate optimal strategies for the combinations of non-lethal (e.g., NTFP) and lethal (e.g., timber) harvest that minimize the cost of harvesting while maximizing the benefits (revenue) that accrue to harvesters and the conservation value of harvested ecosystems. Optimal harvesting strategies include starting with non-lethal NTFP harvest and postponing lethal timber harvesting to begin after a few years. We clearly demonstrate that slow growth species have lower optimal harvesting rates, objective functional values and profits than fast growth species. However, contrary to expectation, the effect of species lifespan on optimal harvesting rates was weak suggesting that life history is a better indicator of species resilience to harvest than lifespan. Overall, lethal or nonlethal harvest rates must be <40 % to ensure optimality. This optimal rate is lower than commonly reported sustainable harvest rates for non-timber forest products.
Similar content being viewed by others
References
Armsworth PR, Armsworth AN, Compton N, Cottle P, Davies I, Emmett BA, Fandrich V, Foote M, Gaston KJ, Gardiner P et al (2010) The ecological research needs of business. J Appl Ecol 47 (2):235–243
Armsworth PR, Block BA, Eagle J, Roughgarden JE (2011) The role of discounting and dynamics in determining the economic efficiency of time-area closures for managing fishery bycatch. Theor Ecol 4(4):513–526
Avocevou Ayisso C, Sinsin B, Adegbidi A, Dossou G, Van Damme P (2009) Sustainable use of non-timber forest products: impact of fruit harvesting on Pentadesma butyracea regeneration and financial analysis of its products trade in Benin. For Ecol Manage 257(9):1930–1938
Hernandez Barrios JC, Anten NP, Martinez-Ramos M (2015) Sustainable harvesting of non-timber forest products based on ecological and economic criteria. J Appl Ecol 52(2):389–401
Bawa K, Kress W, Nadkarni N, Lele S (2004) Beyond paradise—meeting the challenges in tropical biology in the 21st century. Biotropica 36(4):437–446
Bernal R (1998) Demography of the vegetable ivory palm Phytelephas seemannii in Colombia, and the impact of seed harvesting. J Appl Ecol 35(1):64–74
Brazee R, Mendelsohn R (1988) Timber harvesting with fluctuating prices. For Sci 34(2):359–372
Caswell H (2001) Matrix population models: construction, analysis, and interpretation. Sinauer Associates Inc
Chang SJ (1998) A generalized faustmann model for the determination of optimal harvest age. Can J Forest Res 28(5):652–659
Clark CW (2010) Mathematical bioeconomics: the mathematics of conservation, vol 91. Wiley
Cosyns H, Degrande A, De Wulf R, Van Damme P, Tchoundjeu Z (2011) Can commercialization of ntfps alleviate poverty? A case study of Ricinodendron heudelotii (Baill.) Pierre ex Pax. kernel marketing in Cameroon. J Agric Rural Dev Trop Subtrop 112(1):45–56
Cunningham A, Mbenkum F (1993) Sustainability of harvesting Prunus africana bark in Cameroon. People and Plants Working Paper 2, Paris, UNESCO 2
Emanuel P, Shackleton C, Baxter J (2005) Modelling the sustainable harvest of Sclerocarya birrea subsp. caffra fruits in the South African lowveld. For Ecol Manage 214(1):91– 103
Fister KR, Lenhart S, McNally JS (1998) Optimizing chemotherapy in an HIV model. Electronic Journal of Differential Equations 1998(32):1–12
Fleming WH, Rishel RW (1975) Deterministic and stochastic optimal control. Springer, New York
Gaoue OG, Ticktin T (2007) Patterns of harvesting foliage and bark from the multipurpose tree Khaya senegalensis in Benin: variation across ecological regions and its impacts on population structure. Biol Conserv 137 (3):424–436
Gaoue OG, Ticktin T (2009) Fulani knowledge of the ecological impacts of Khaya senegalensis (Meliaceae) foliage harvest in Benin and its implications for sustainable harvest. Econ Bot 63(3):256–270
Gaoue OG, Ticktin T (2010) Effects of harvest of nontimber forest products and ecological differences between sites on the demography of African mahogany. Conserv Biol 24(2): 605–614
Gaoue OG, Horvitz C, Ticktin T (2011) Non-timber forest product harvest in variable environments: modeling the effect of harvesting as a stochastic sequence. Ecol Appl 21(5):1604– 1616
Gaoue OG, Ngonghala C, Jiang J, Lelu M (2015) Towards a mechanistic understanding of the synergistic effects of harvesting on timber and non-timber forest products. Methods in Ecology & Evolution. doi:10.1111/2041-210X.12493
Godoy R, Wilkie D, Overman H, Cubas A, Cubas G, Demmer J, McSweeney K, Brokaw N (2000) Valuation of consumption and sale of forest goods from a Central American rain forest. Nature 406(6791):62–63
Gopalakrishnan C, Wickramasinghe W, Gunatilake H, Illukpitiya P (2005) Estimating the demand for non-timber forest products among rural communities: a case study from the Sinharaja rain forest region, Sri Lanka. Agrofor Syst 65(1):13–22
Grogan J, Landis RM, Free CM, Schulze MD, Lentini M, Ashton MS (2014) Big-leaf mahogany Swietenia macrophylla population dynamics and implications for sustainable management. J Appl Ecol 51(3):664–674
Guariguata MR, Licona JC, Mostacedo B, Cronkleton P (2009) Damage to brazil nut trees (Bertholletia excelsa) during selective timber harvesting in northern bolivia. For Ecol Manage 258(5):788–793
Guariguata MR, García-Fernández C, Sheil D, Nasi R, Herrero-Jáuregui C, Cronkleton P, Ingram V (2010) Compatibility of timber and non-timber forest product management in natural tropical forests: perspectives, challenges, and opportunities. For Ecol Manage 259(3):237–245
Guedje N, Zuidema P, During H, Foahom B, Lejoly J (2007) Tree bark as a non-timber forest product: the effect of bark collection on population structure and dynamics of Garcinia lucida Vesque. For Ecol Manage 240 (1):1–12
Hall P, Bawa K (1993) Methods to assess the impact of extraction of non-timber tropical forest products on plant populations. Econ Bot 47(3):234–247
Hamilton A (2004) Medicinal plants, conservation and livelihoods. Biodivers Conserv 13(8):1477–1517
Hardie IW, Daberkow JN, McConnell KE (1984) A timber harvesting model with variable rotation lengths. For Sci 30(2):511–523
Joshi HR, Herrera GE, Lenhart S, Neubert MG (2009) Optimal dynamic harvest of a mobile renewable resource. Nat Resour Model 22(2):322–343
Kasperski S, Wieland R (2009) When is it optimal to delay harvesting? the role of ecological services in the northern chesapeake bay oyster fishery. Mar Resour Econ 24(4):361–385
Klimas C, Cropper Jr W, Kainer K, de Oliveira Wadt L (2012a) Viability of combined timber and non-timber harvests for one species: a Carapa guianensis case study. Ecol Model 246:147–156
Klimas C, Kainer K, de Oliveira Wadt L (2012b) The economic value of sustainable seed and timber harvests of multi-use species: an example using Carapa guianensis. For Ecol Manage 268: 81–91
Lande R, Engen S, Saether BE (1994) Optimal harvesting, economic discounting and extinction risk in fluctuating populations. Nature 372(6501):88–90
Lenhart S, Workman JT (2007) Optimal control applied to biological models. CRC Press
Lukes DL (1982) Differential equations: Classical to controlled. Academic Press, INC, New York
Macpherson AJ, Carter DR, Schulze MD, Vidal E, Lentini MW (2012) The sustainability of timber production from eastern amazonian forests. Land Use Policy 29(2):339–350
Marino S, Hogue IB, Ray CJ, Kirschner DE (2008) A methodology for performing global uncertainty and sensitivity analysis in systems biology. J Theor Biol 254(1):178–196
Miller Neilan RL, Schaefer E, Gaff H, Fister KR, Lenhart S (2010) Modeling optimal intervention strategies for cholera. Bull Math Biol 72(8):2004–2018
Mondragon CD, Ticktin T (2011) Demographic effects of harvesting epiphytic bromeliads and an alternative approach to collection. Conserv Biol 25(4):797–807
Ndoye O, Tieguhong JC (2004) Forest resources and rural livelihoods: the conflict between timber and non-timber forest products in the Congo Basin. Scand J For Res 19(S4):36–44
Neubert MG, Herrera GE (2008) Triple benefits from spatial resource management. Theor Ecol 1(1):5–12
Newman DH, Gilbert CB, Hyde WF (1985) The optimal forest rotation with evolving prices. Land Econ 64(4):347–353
Peres C, Baider C, Zuidema P, Wadt L, Kainer K, Gomes Silva D, Salomão R, Simões L, Franciosi E, Valverde F et al (2003) Demographic threats to the sustainability of Brazil nut exploitation. Science 302(5653):2112–2114
Peters CM (1994) Sustainable harvest of non-timber plant resources in tropical moist forest: an ecological primer. Biodiversity Support Program, Washington, DC
Pimentel D, McNair M, Buck L, Pimentel M, Kamil J (1997) The value of forests to world food security. Human Ecology 25(1):91–120
Plantinga AJ (1998) The optimal timber rotation: an option value approach. For Sci 44(2):192–202
Pontryagin LS, Boltyanskii VG, Gamkrelize RV, Mishchenoko EF (1962) The mathematical theory of optimal processes. Wiley
Potts MD, Vincent JR (2008) Harvest and extinction in multi-species ecosystems. Ecological Economics 65(2):336–347
Rist L, Shanley P, Sunderland T, Sheil D, Ndoye O, Liswanti N, Tieguhong J (2012) The impacts of selective logging on non-timber forest products of livelihood importance. For Ecol Manage 268(1):57–69
SCBD (2001) Sustainable management of non-timber forest resources. Secretariat of the Convention on Biological Diversity, CBD Technical Series no. 6
Schippmann U, Cunningham A, Leaman D et al (2003) Impact of cultivation and gathering of medicinal plants on biodiversity: global trends and issues. In: Biodiversity and the ecosystem approach in agriculture, forestry and fisheries. Proceedings, Rome, Italy, 12-13 October 2002., Food and Agriculture Organization of the United Nations (FAO), pp 140–167
Schippmann U, Leaman D, Cunningham A (2006) A comparison of cultivation and wild collection of medicinal and aromatic plants under sustainability aspects. Frontis 17:75–95
Schmidt IB, Mandle L, Ticktin T, Gaoue OG (2011) What do matrix population models reveal about the sustainability of non-timber forest product harvest? J Appl Ecol 48:815– 826
Shackleton C, Shackleton S (2004) The importance of non-timber forest products in rural livelihood security and as safety nets: a review of evidence from South Africa. S Afr J Sci 100(11 & 12): 658
Shackleton CM, Pandey AK (2014) Positioning non-timber forest products on the development agenda. Forest Policy and Economics 38:1–7
Shackleton S, Delang CO, Angelsen A (2011) From subsistence to safety nets and cash income: exploring the diverse values of non-timber forest products for livelihoods and poverty alleviation. Springer
Silvertown J (2004) Sustainability in a nutshell. Trends Ecol Evol 19(6):276–278
Soehartono T, Newton CA (2001) Conservation and sustainable use of tropical trees in the genus Aquilaria II. The impact of gaharu harvesting in Indonesia. Biol Conserv 97(1):29–41
Stewart K (2009) Effects of bark harvest and other human activity on populations of the African cherry (Prunus africana) on Mount Oku, Cameroon. For Ecol Manage 258(7):1121– 1128
Ticktin T (2004) The ecological implications of harvesting non-timber forest products. J Appl Ecol 41(1):11–21
Ticktin T (2015) The ecological sustainability of non-timber forest product harvest: principles and methods. In: Shackleton CM, Pandey AK, Ticktin T (eds) Ecological sustainability for non-timber forest products: dynamics and case studies of harvesting, Routledge, pp 31–52
Ticktin T, Nantel P, Ramirez F, Johns T (2002) Effects of variation on harvest limits for nontimber forest species in Mexico. Conserv Biol 16(3):691–705
Ticktin T, Ganesan R, Paramesha M, Setty S (2012) Disentangling the effects of multiple anthropogenic drivers on the decline of two tropical dry forest trees. J Appl Ecol 49:774– 784
van Andel T, Havinga R (2008) Sustainability aspects of commercial medicinal plant harvesting in suriname. For Ecol Manag 256(8):1540–1545
Vodouhê FG, Coulibaly O, Greene C, Sinsin B, 2009 Estimating the local value of non-timber forest products to pendjari biosphere reserve dwellers in Benin. Econ Bot 63(4):397–412
Zuidema P, Boot R (2002) Demography of the Brazil nut tree (Bertholletia excelsa) in the Bolivian Amazon: impact of seed extraction on recruitment and population dynamics. J Trop Ecol 18(1):1–31
Zuidema P, de Kroon H, Werger M (2007) Testing sustainability by prospective and retrospective demographic analyses: evaluation for palm leaf harvest. Ecol Appl 17(1):118–128
Acknowledgments
This work was supported by fellowships from the National Institute for Mathematical and Biological Synthesis (NIMBioS) at The University of Tennessee, Knoxville, sponsored by the National Science Foundation (NSF Grant # EF-0832858). OGG was supported by a start-up Grant from the College of Natural Sciences at the University of Hawaii at Manoa. We are grateful to Robert McElderry, Lalasia Bialic-Murphy, and anonymous reviewers for valuable comments on an earlier version of this manuscript.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Gaoue, O.G., Jiang, J., Ding, W. et al. Optimal harvesting strategies for timber and non-timber forest products in tropical ecosystems. Theor Ecol 9, 287–297 (2016). https://doi.org/10.1007/s12080-015-0286-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12080-015-0286-4