Influence of Miombo woodlands management, drivers on land use/cover and forest change, woody composition/diversity, population structure in Malawi

The Miombo woodland vegetation of southern Africa has been subjected to anthropogenic pressures in recent years, resulting in a change in its cover and floristic-structural composition, and the population status of important tree species. The recent land use land cover changes (LULCC) is of concern due to the negative impacts on the Miombo woodland ecological functions. Understanding the overall dynamics of the vegetation that include LULCC, forest cover change, tree species composition, and diversity, population structure (PS) in relation to forest degradation, loss of endangered/rare species, is pivotal in influencing policy and sustainable woodland management. The Malawi Government instituted policies that allowed for improved forest management. However, the impact of forest management regimes on forest cover, tree species diversity, and structure is not well established. The study aimed to determine LULCC and forest cover changes and the associated drivers and how co-management (CM) and government-management (GM) impact on the florist-structural composition, diversity and the population structure of the important tree species in Malawian Miombo landscape. Firstly, the study analysed LULCC and the comparative impact of CM and GM on the forest cover in Malawi, for the period 1999-2018. CM involves a contractual agreement between communities (with a forest management plan who have been empowered to manage forest resources) and the Forest Department (representing the Government) in managing forest reserves. GM is the protection of forest resources by the government through the Forest Department. Since the introduction of participatory forest management (PFM), such as CM, its impact has not been established. Google Earth images (Landsat mosaics) for 1999 and 2018 for Malawi were acquired, registered, and pre-processed in Environment for Visualizing Images (ENVI 4.7) Harris Geospatial Solutions. LULCC estimation using the Inter-Governmental Panel on Climate Change (IPCC) classes was determined using the differences in error-adjusted areas between 1999 and 2018. Overall accuracies were >90%. Woodland net losses of 8.4% were to Plantation, Grassland, and Agriculture transition intensities. Agriculture net gains of 9.6% were from Grassland, Settlement, and Woodland transitions for Malawi. Forest cover within CM and GM indicated losses. Participatory land use plans and monitoring for diversified management in Malawian Miombo woodlands are required to mitigate anticipated irreversible impacts in the landscape. The second study investigated the factors that influence changes in CM and GM forest reserves between 1999 and 2018. CM and GM regimes in Miombo woodlands are possible interventions to mitigate forest degradation and deforestation in southern Africa. However, few studies have investigated the direct and indirect drivers of LULCC using socioeconomic characteristics and Remote sensing data in CM and GM regimes. The drivers of LULCC in forest reserves, and management challenges were identified using participatory assessments in both management regimes. The changes in woodland were observed with varying extent. Communities' perceptions in the factors contributing to changes in CM and GM forest reserves were similar and mostly due to the conversion of woodlands to agriculture while extraction of woody products led to forest degradation. In both management strategies, population pressure, youthful age, poverty, and poor education were associated with forest-based livelihood activities and therefore the woodland changes. The overall woodland cover loss to grassland is attributed to its importance as a source of energy. There is thus a need to harmonize policies for sustainable use and management of woodlands in order to address local, national, and regional ecosystem services. Future studies will need to link Remote sensing and socioeconomic data as part of a monitoring tool that could assist to sustainably adapt to changes in the woodlands and surrounding communities. The third study compared the Miombo Tree species composition and diversity between CM and GM regimes in Malawi. Tree species composition and diversity information is limited between CM and GM regimes. Two CM and two GM forest reserves were purposively selected to act as representatives of management regimes in the northern and southern regions of Malawi. Forest inventory data from 80 randomly selected nested circular plots were used. Two plot sizes: a large plot (0.16 ha; radius 22.6 m) to record stems ≥30 cm DBH, and the main plot (0.04 ha; radius 11.28 m) to record stems 5.0-29.9 cm DBH and species names. In total, 109 tree species belonging to 38 families, 87 species in GM FRs (Kaning’ina 58, Thambani 52), and 69 in CM FRs (Perekezi 45, Liwonde 43) were recorded. The largest families (number of species between brackets) were Fabaceae (34, with 3 subfamilies, Caesalpinioideae (17), Papilionoideae (12), and Mimosoideae (5), an indication of their adaptive potential in the area. Other important families were Combretaceae (7), Rubiaceae (7), and Clusiaceae (4). Species similarity between management regimes was low and was attributed to site factors, species characteristics and intensity of disturbances. TWINSPAN classification results were related to differences in site conditions and disturbances caused by historical and current resource use in management regimes. The eigenvalues ≥0.3 across CM and GM sub-communities indicated high stability. Brachystegia and Julbernardia species were highly important in CM and GM sub-communities. Uapaca species were highly important in agriculture and settlement abandoned areas in GM forest reserve. The study recommends selective harvesting to allow for dominant (Brachystegia and Julbernardia) and associated Miombo species to regenerate. Species richness and evenness (diversity) was high in more disturbed CM and GM sub-communities compared to intact areas. The high diversity was related to tree species high abundances of smaller stems with few scattered big trees. These results call for a Forest policy review to allow planned harvesting in GM forest reserves. Law enforcement is also required in both management regimes to mitigate unsustainable harvesting in sensitive areas. Future studies should include zonation to improve differentiation between site factors and wood extraction in stand development stages in management regimes. The fourth study compared the Miombo population structure (PS) between CM and GM regimes. Such information is limited in CM and GM regimes since the introduction of PFM in Malawi. The size class distribution (SCD) of sub-canopy/canopy species showed a reversed J-shaped profile in CM and GM forest reserves (South), when compared to CM and GM, in northern Malawi. These findings may reflect differences in the historical woodland utilization in the two regions. The bell-shaped SCDs in CM sub-communities with high stem density of Brachystegia and Julbernardia species suggest strong demand for light for successful recruitment from regeneration to adult trees and could be related to wood utilization. The reversed J-shape SCDs in northern GM sub-communities with high regeneration stem density of Pittosporum viridiflorum suggest an increase in shade-tolerant evergreen tree species under a low-level disturbance. Timber species showed interrupted SCDs with few to no stems, indicating challenges in regeneration. Pioneer species were associated with disturbances under CM indicating woodland recovery. The patterns in SCD showed similarities and differences between CM and GM sub-communities between the two management strategies. In Community 2, there were significant differences (p = 0.002) between management strategies with low canopy densities in CM, which could be attributed to unsustainable harvesting. Furthermore, saplings showed significant differences with a higher stems ha-1 in CM compared to GM. Trees and regeneration SCDs suggest a thorough analysis of the PS of varied species associations to guide sustainable resource use. An adaptive management approach that uses silvicultural systems to promote sustainable forest management is recommended. Additionally, selective harvesting in recovery stages would reduce intense competition in the dense, even-aged stands. However, there is need for instituting enabling policies and to monitor changes in both management regimes to promote biodiversity conservation, resource use, and diverse ecosystem services at all levels.