Prediction of forest parameters and carbon accounting under different fire regimes in Miombo woodlands

Highlights

• FORMIND model reproduces the miombo woodlands structure in Niassa Special Reserve.
• Fires may reduce the miombo capacity to mitigate the effects of climate change.
• Effective fire management is key to sustaining the miombo woodlands.
• There is great potential for C projects based on fire management in miombo.
• There is need to raise awareness on fire management benefits.

Abstract

Miombo woodlands are the most extensive dry forest type in southern Africa, covering ca. 1.9 million km² across seven countries. Fire is a key ecosystem process that has structured miombo for the last 200,000 years. However, how fires affect the ecosystem's functioning is not well understood. In this study, we used the individual-based forest model called FORMIND to analyze the carbon balance in the miombo woodlands of Niassa Special Reserve (NSR), northern Mozambique. The 42.000 km² NSR represents the most important conservation area in Mozambique (~31% of the total conservation area in the country) and of miombo woodlands worldwide. Long-term inventory data from 2004 to 2019 for NSR were used to calibrate FORMIND. The primary ecosystem processes of this model are tree growth, mortality, regeneration, and competition. Fire is set as one of the main factors that affect these processes, after the woodland reaches an equilibrium at 200 years of age. We also calculated the Net Present Value (NPV) of carbon creditsresulting from altering the fire regime (e.g., reducing or eliminating fires). The FORMIND model successfully reproduced important characteristics of the woodlands (aboveground biomass, stem size distribution and basal area). NPV estimates of above-ground woody biomass carbon stocks were highly dependent on the woodland age. The maximum NPV estimates were generated for a 30-year project starting with 200 year old woodlands (the current forest age) at 192–1339 USD based on a realistic range of carbon values (i.e., 3–20 USD MgCO₂e⁻¹). While fire plays an important role in miombo woodlands by reducing stock and changing species composition, its effects on the capacity of the woodland to mitigate the effects of climate change varies depending on the age of stands. Our results show that FORMIND model reliably reproduce the field inventory data, thus can be used to improve carbon accounting standards. We recommend the development of a fire management system to sustain the miombo woodlands of NSR for multiple reasons. NSR is a globally significant protected area, but perhaps more importantly it could become a regional example for how to improve miombo woodland management. Given that miombo woodlands provide a myriad of ecosystem services to rural Africans, investing in improving fire management could increase the benefits to local communities. Altering fire regimes could improve habitat quality and promote greater resilience to climate change while sequestering carbon. In addition, local employment opportunities in fire management could be created via carbon financing from a carbon project. However, much more outreach and education will be needed to local and national stakeholders for fire management to be perceived more positively and realize the potential to generate multiple benefits for nature and people.