The government ban on exotic tree species such as eucalyptus and acacia during the current planting season has sparked debate among the public, policymakers, and forestry professionals in both mainstream and social media platforms. Supporters argue that these fast-growing species are vital for timber production and rural livelihoods. Critics, however, see them as ecological risks that should be replaced with native alternatives. This debate resurfaces almost every planting season but remains unresolved. The reason is simple: strong opinions exist on both sides, but few are backed by locally relevant scientific evidence. This shows a broader challenge in Bangladesh's forestry sector: policies often advance before consulting the research needed to justify or support them, although national forestry, environmental, and climate strategies consistently identify scientific research as a priority. This does not mean that research on these species is absent. In fact, a substantial body of international literature has examined the ecological, hydrological, and economic impacts of eucalyptus and acacia. However, research within Bangladesh is often constrained by short study periods, limited geographic coverage, and insufficient long-term monitoring. As a result, a fundamental question remains unanswered: what specific roles do exotic eucalyptus and acacia play in Bangladesh's ecological and socio-economic systems? Answering this question will require understanding not only the patterns of ecological and economic impacts but also the mechanisms behind them. Ecological impacts are likely to vary with rainfall, groundwater availability, soil characteristics and planting design; economic impacts, on the other hand, are likely to depend on individual, local or regional economic conditions and livelihood traditions. Thus, findings from other countries cannot be directly applied to Bangladesh's diverse biogeological zones without local validation. Even within the country, ecological impacts and productivity of these species are likely to differ between the drought-prone northwest and the flood-prone southwest regions. That being said, supporters of eucalyptus and acacia often highlight their well-established nursery systems, widely available silvicultural knowledge on these species, and strong local demand. These benefits are genuine, but they are the outcome of decades of investment under a forestry policy that prioritised timber production. During the 1980s, timber production was a primary forestry objective and exotic species were not considered problematic. At that time, the Bangladesh Forest Research Institute (BFRI) invested in fast-growing exotics and conducted species and silvicultural trials on their growth and yield. BFRI even experimented with introducing mainland species into the Sundarbans (e.g., near Hironpoints), but fortunately, the experiment failed. Otherwise, Bangladesh might now be confronting an invasion problem in the Sundarbans. In sum, all these investments built a knowledge base on eucalyptus and acacia, and these species became embedded in our nursery systems, plantation practices, and local markets. Over time, however, global forestry priorities have shifted from timber production toward biodiversity conservation, ecosystem restoration, and climate resilience. Bangladesh, too, embraced this broader policy direction. While doing so, we have found ourselves in somewhat of an unusual position: our policy transition has not been matched by investments in research, nursery development, and market development for native species. Encouragingly, the Bangladesh Forest Department has identified several native species for the current planting season and is moving toward site-specific species selection. However, we do not know much about the growth performance, ecological functions, climate resilience, community preferences, and market potential of many of the native species that are under plantation conditions. But, delaying the transition to native species is also not a productive idea. Since there is no technical barrier to studying and integrating native species into our plantation systems, what Bangladesh should do is develop a national forestry research agenda. Universities, BFRI, the Bangladesh Forest Department, and environmental organisations need to collaborate to establish long-term experimental plantations across the country's diverse bioecological zones. Ideally, a broad range of native species should be evaluated using standardised measures of growth, water use, carbon storage, soil health, biodiversity, ecosystem functions and services, economic returns, and social benefits across complete rotation cycles. Research should also assess their performance in mixed-species plantations, their resilience to climate change, their susceptibility to pests, and their suitability for landscape-scale restoration. Only through these kinds of long-term experiments can we answer key questions, such as which biodiversity-friendly and climate-resilient native species can provide communities with comparable financial returns and reliable markets. However, this is only the first step. Integrating this knowledge into forestry policy and extension efforts is crucial. Besides, forestry systems are dynamic. While there has been a shift from production-oriented forestry towards biodiversity conservation, the understanding of biodiversity itself is also evolving. In Bangladesh, biodiversity is often seen as only species diversity, while global conservation frameworks recognise the importance of functional and phylogenetic diversity. So, future forestry strategies in Bangladesh need to incorporate these broader perspectives as well. Global forestry policy too will continue to evolve in response to climate change, emerging pests, market shifts, and changing conservation priorities. Bangladesh's forestry institutions must be prepared in advance to evolve with it by continuously generating and applying new scientific evidence. This adaptive approach is essential for achieving national and global commitments on biodiversity conservation, climate adaptation, carbon sequestration, and sustainable development. Decisions about plantation species will impact all of these objectives, so they must be guided by evidence rather than assumptions or traditions. In conclusion, Bangladesh requires sustained investment in scientific research, long-term experimentation, and the willingness to adjust policies as new evidence emerges. We must understand that strong opinions will always shape public debate, but only strong science can sustain effective and resilient forestry policy. Shekhar R Biswas is professor of ecology at East China Normal University in Shanghai. Views expressed in this article are the author's own. Follow The Daily Star Opinion on Facebook for the latest opinions, commentaries, and analyses by experts and professionals. To contribute your article or letter to The Daily Star Opinion, see our guidelines for submission.