Browsing by Author "Marchant, Robert"

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Detecting and predicting forest degradation: a comparison of ground surveys and remote sensing in Tanzanian forests
(Plants, People, Planet (PPP), 2021-01-08) Ahrends, Antje; Bulling, Mark T.; Platts, Philip J.; Swetnam, Ruth; Ryan, Casey; Doggart, Nike; Hollingsworth, Peter M.; Marchant, Robert; Balmford, Andrew; Harris, David J.; Gross-Camp, Nicole; Sumbi, Peter; Munishi, Pantaleo; Madoffe, Seif; Mhoro, Boniface; Leonard, Charles; Bracebridge, Claire; Doody, Kathryn; Wilkins, Victoria; Owen, Nisha; Marshall, Andrew R.; Schaafsma, Marije; Pfliegner, Kerstin; Jones, Trevor; Robinson, James; Topp-Jørgensen, Elmer; Brink, Henry; Burgess, Neil D.
Tropical forest degradation is widely recognised as a driver of biodiversity loss and a major source of carbon emissions. However, in contrast to deforestation, more gradual changes from degradation are challenging to detect, quantify and monitor. Here, we present a field protocol for rapid, area-standardised quantifications of forest condition, which can also be implemented by non-specialists. Using the ex- ample of threatened high-biodiversity forests in Tanzania, we analyse and predict degradation based on this method. We also compare the field data to optical and radar remote-sensing datasets, thereby conducting a large-scale, independent test of the ability of these products to map degradation in East Africa from space. • Our field data consist of 551 ‘degradation’ transects collected between 1996 and 2010, covering >600 ha across 86 forests in the Eastern Arc Mountains and coastal forests. • Degradation was widespread, with over one-third of the study forests—mostly protected areas—having more than 10% of their trees cut. Commonly used opti- cal remote-sensing maps of complete tree cover loss only detected severe im- pacts (≥25% of trees cut), that is, a focus on remotely-sensed deforestation would have significantly underestimated carbon emissions and declines in forest quality. Radar-based maps detected even low impacts (<5% of trees cut) in ~90% of cases. The field data additionally differentiated types and drivers of harvesting, with spa- tial patterns suggesting that logging and charcoal production were mainly driven by demand from major cities. • Rapid degradation surveys and radar remote sensing can provide an early warning and guide appropriate conservation and policy responses. This is particularly im- portant in areas where forest degradation is more widespread than deforestation, such as in eastern and southern Africa.
From local scenarios to national maps: a participatory framework for envisioning the future of Tanzania
(Resilience Alliance Inc, 2016) Capitani, Claudia; Mukama, Kusaga; Mbilinyi, Boniface; Malugu, Isaac O.; Munishi, Pantaleo K. T.; Burgess, Neil D.; Platts, Philip J.; Sallu, Susannah M.; Marchant, Robert
Tackling societal and environmental challenges requires new approaches that connect top-down global oversight with bottom-up subnational knowledge. We present a novel framework for participatory development of spatially explicit scenarios at national scale that model socioeconomic and environmental dynamics by reconciling local stakeholder perspectives and national spatial data. We illustrate results generated by this approach and evaluate its potential to contribute to a greater understanding of the relationship between development pathways and sustainability. Using the lens of land use and land cover changes, and engaging 240 stakeholders representing subnational (seven forest management zones) and the national level, we applied the framework to assess alternative development strategies in the Tanzania mainland to the year 2025, under either a business as usual or a green development scenario. In the business as usual scenario, no productivity gain is expected, cultivated land expands by ~ 2% per year (up to 88,808 km2), with large impacts on woodlands and wetlands. Despite legal protection, encroachment of natural forest occurs along reserve borders. Additional wood demand leads to degradation, i.e., loss of tree cover and biomass, up to 80,426 km2 of wooded land. The alternative green economy scenario envisages decreasing degradation and deforestation with increasing productivity (+10%) and implementation of payment for ecosystem service schemes. In this scenario, cropland expands by 44,132 km2 and the additional degradation is limited to 35,778 km2. This scenario development framework captures perspectives and knowledge across a diverse range of stakeholders and regions. Although further effort is required to extend its applicability, improve users’ equity, and reduce costs the resulting spatial outputs can be used to inform national level planning and policy implementation associated with sustainable development, especially the REDD+ climate mitigation strategy.