Sustainability Science for Tropical Forests

Deep Narayan Pandey

• Responses to this Article
• Acknowledgments
• Literature Cited

Published: June 4, 2002

Tropical forests are vital for social, economic, and ecological reasons. They play an important role in ecosystem processes (such as the biogeochemical and hydrological cycles), they provide habitat for wildlife and serve as sources of biodiversity, and they offer protection against soil erosion (Kremen et al. 2000, Sala et al. 2000, Pandey, 2001, Condit et al. 2002). In this era of global warming (Forest et al. 2002), tropical forests help mitigate the effects of climate change (Phillips et al. 1998, Schimel et al. 2001), and maintain biodiversity and ecosystem functioning (Loreau et al. 2001). However, in spite of their obvious value, human activity is causing unprecedented threats to tropical forest ecosystems (Noble and Dirzo 1997). Therefore, the study by Elmqvist et al. (2001) on the essential components of spatial resilience in tropical forest ecosystems is useful and timely.

Although I agree with Elmqvist et al. (2002) that active management of tropical forests that have been exposed to large-scale disturbances should focus on the management of remnant trees, refugia, and vertebrate dispersers, I would, however, suggest that we need broader strategies to maintain the resilience and regenerative capacity of these tropical forests to ensure their sustainability. The regenerative capacities of disturbed, fragmented, or harvested tropical forests provide hope, and a clear message about how to prevent further species loss (Chazdon 1998).

It might be useful to examine some core issues of sustainability science (Kates et al. 2001) for tropical forests that may have some bearing on resilience and, therefore, on sustainability of tropical forests.

The core issues (Kates et al. 2001) we should be asking in order to assess ecosystems (Ayensu et al. 1999), and thus help formulate adaptive tropical forest management, might include the following.

• Incorporation of nature–society interactions into models of Earth systems, human development, and sustainability. Practices contributing to tropical forest sustainability, biodiversity conservation, and livelihood security may help integrate a new adaptive paradigm. Specifically, can an “ecologically focused perspective” create a vision of sustainably managed tropical forests, in which logging mimics natural forest disturbances and forest regeneration is adaptively and actively promoted (Chazdon 1998)? Sustainable forest management, which is still controversial, requires careful monitoring in areas where logging is taking place (Bowles et al. 1998) to see how it affects the ecosystem and people (Cox 2000, Janzen 1998).

• Insights about the changing nature–society interactions caused by long-term trends in population and consumption. Studying the effects of a growing population on harvest and regeneration can provide insights about this core issue. For instance, climate change caused by changing land use in tropical lowlands may have serious consequences for adjacent tropical forest ecosystems (Lawton et al. 2001). Similarly, socioeconomic factors that bring about tropical deforestation require us to take corrective measures (Bawa and Dayanandan 1997). Such long-term trends can provide guidance in the management not only of tropical forests but also of adjacent areas.

• Contextual factors related to the vulnerability or resilience of the nature–society system. Factors that save tropical forests from catastrophic shifts also help maintain resilience. There is strong, widespread consensus among forest ecologists and conservation biologists that recovery of degraded or cleared forests hinges upon close proximity to genetically diverse and demographically stable source populations (Chazdon 1998). In tropical forests, large trees provide habitats for several other species. Forest fragments in otherwise deforested areas serve as sources for future tree populations. Seed dispersal may, however, be limited. Thus, forest fragments as large as 10 hectares may have been founded from a single maternal lineage (Hamilton 1999). Furthermore, fragmentation of tropical forests kills the big trees (Laurance et al. 2000) that act as seed sources and habitat for mammals, birds, insects, and other animals. This problem is compounded, because seeds planted in forest fragments are less likely to germinate than those in continuous forest (Bruna 1999). Restoration should not rely solely on regeneration and recruitment, but should also make use of and promote the remaining root-stock in the persistence niche (Bond and Midgley 2001). This aspect is often ignored in research and in practice. We need to take a holistic approach to maintaining tropical forest resilience.

• Limits on resource use. We need to probe more deeply to get insights about the limits of sustainable harvests in tropical forests, and the factors that promote such desirable behavior in society. For instance, indiscriminate harvest in the Amazon rain forest may remove trees that are more than 1400 years old (Chambers et al. 1998), releasing a large amount of CO₂ back in the atmosphere.

• Ethics, incentives, and knowledge that promote sustainable nature–society interactions. Economic incentives for rain-forest conservation across scales are a must (Kremen et al. 2000). We often find examples where the local management practices of village communities follow a variety of norms and rules. Knowing such systems of incentive structures, including markets, rules, norms, information, knowledge, and wisdom, can improve our capacity to steer interactions between nature and society in a sustainable direction.

• Comprehension of crucial knowledge. For practitioners, a simple monitoring and feedback mechanism must become routine to help them make harvest and management decisions using knowledge networks across scales. This can help in designing the operational systems for assessing sustainability, and monitoring and reporting on ecological and social conditions within tropical forest ecosystems.

• Bringing researchers, planners, policy analysts, and practitioners together to learn, decide, and implement adaptive management. There is an urgent need to integrate the relatively independent activities of research, planning, monitoring, assessment, and decision support into systems for societal learning and adaptive management of tropical forests. Society has been greatly lacking in this regard.

In conclusion, I would reiterate that tropical forests are vital for social, economic, and ecological reasons. We need to explore the core questions of sustainability science in the context of tropical forests and design robust policy and practice for adaptive tropical forest management if we are to mitigate the negative effects of human intervention in these ecosystems.

Responses to this article are invited. If accepted for publication, your response will be hyperlinked to the article. To submit a comment, follow this link. To read comments already accepted, follow this link.

I am grateful to Shri N. K. Joshi, Director, Indian Institute of Forest Management Bhopal, Dr. Ram Prasad, PCCF of Madhya Pradesh, and Caroline Simpson for helpful suggestions. Support from the Ford Foundation and Winrock International is gratefully acknowledged.

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