Adopting early dry season fires in African conservation areas has been proposed as ecologically desired and a means of generating sufficient carbon revenues for their management. We interrogate available peer-reviewed information on the ecology and biogeochemistry of fire in Africa to offer an informed perspective on the full implications of the proposal. We conclude that there is insufficient evidence that a shift to early dry season fires will reduce greenhouse gas emissions, that resultant biodiversity and ecosystem service outcomes may not be desired, and that adopting a single burning regime limits the use of fire to achieve a diverse range of goals. Adopting early dry season fires has been proposed as a means of generating sufficient carbon revenues to pay for conservation in Africa. However, the climatic impact thereof is deeply questionable and may have unforeseen detrimental effects.

Aim Despite their extent (40 degrees of latitude and 50 degrees of longitude), research in African savannas is dominated by a few heavily studied areas. We gathered data from African savanna protected areas to (i) evaluate their contributions to the primary literature, (ii) identify environmental groupings with respect to climate, soils, and landscape variables, and (iii) analyze the determinants of tree cover and fire within groupings. Location Africa. Methods We extracted climate, soil, topography, hydrology, elephant, fire, and tree cover data from polygon boundaries for 244 African savanna protected areas. The polygon layers and data were assembled into a novel geodatabase: African Database of Savanna Protected Areas (ADSPA). Cluster analysis identified natural bioclimatic groupings and structural equation modelling was used to analyse and compare the drivers of fire and tree cover within and across clusters. Results Previous literature disproportionately focused on a few savannas: 46% of savanna publications came from 2% of protected areas. Cluster analysis identified five bioclimatic groups: (1) African hot mesic savannas, (2) African cool mesic fertile savannas, (3) West African hot semi-arid savannas, (4) Southern African semi-arid savannas, and (5) Kalahari arid savannas. Current savanna science in protected areas is biased toward the Southern African semi-arid and African cool mesic fertile savannas, while hot mesic, hot semi-arid, and arid savannas are underrepresented. Climate and soils were strongly associated with tree cover and fire across protected areas, but no significant biome-wide effects of fire on tree cover emerged. However, tree cover was negatively related to fire in the hot mesic savanna cluster. Main Conclusions Significant biogeographic and ecological variation within African savannas highlights the need for research across the entire breadth of the biome, especially West Africa. We stress the need for spatially explicit, Africa-wide, data on mammalian herbivore biomass to better assess the importance of this variable for savanna functioning.

Protected areas provide major benefits for humans in the form of ecosystem services, but landscape degradation by human activity at their edges may compromise their ecological functioning. Using multiple lines of evidence from 40 years of research in the Serengeti-Mara ecosystem, we find that such edge degradation has effectively "squeezed" wildlife into the core protected area and has altered the ecosystem's dynamics even within this 40,000-square-kilometer ecosystem. This spatial cascade reduced resilience in the core and was mediated by the movement of grazers, which reduced grass fuel and fires, weakened the capacity of soils to sequester nutrients and carbon, and decreased the responsiveness of primary production to rainfall. Similar effects in other protected ecosystems worldwide may require rethinking of natural resource management outside protected areas.

Fire is a key driver in savannah systems and widely used as a land management tool. Intensifying human land uses are leading to rapid changes in the fire regimes, with consequences for ecosystem functioning and composition. We undertake a novel analysis describing spatial patterns in the fire regime of the Serengeti-Mara ecosystem, document multidecadal temporal changes and investigate the factors underlying these patterns. We used MODIS active fire and burned area products from 2001 to 2014 to identify individual fires; summarizing four characteristics for each detected fire: size, ignition date, time since last fire and radiative power. Using satellite imagery, we estimated the rate of change in the density of livestock bomas as a proxy for livestock density. We used these metrics to model drivers of variation in the four fire characteristics, as well as total number of fires and total area burned. Fires in the Serengeti-Mara show high spatial variability-with number of fires and ignition date mirroring mean annual precipitation. The short-term effect of rainfall decreases fire size and intensity but cumulative rainfall over several years leads to increased standing grass biomass and fuel loads, and, therefore, in larger and hotter fires. Our study reveals dramatic changes over time, with a reduction in total number of fires and total area burned, to the point where some areas now experience virtually no fire. We suggest that increasing livestock numbers are driving this decline, presumably by inhibiting fire spread. These temporal patterns are part of a global decline in total area burned, especially in savannahs, and we caution that ecosystem functioning may have been compromised. Land managers and policy formulators need to factor in rapid fire regime modifications to achieve management objectives and maintain the ecological function of savannah ecosystems.

Abstract Fire is a fundamental process in savannas and is widely used for management. Pyrodiversity, variation in local fire characteristics, has been proposed as a driver of biodiversity although empirical evidence is equivocal. Using a new measure of pyrodiversity (Hempson et al.), we undertook the first continent‐wide assessment of how pyrodiversity affects biodiversity in protected areas across African savannas. The influence of pyrodiversity on bird and mammal species richness varied with rainfall: strongest support for a positive effect occurred in wet savannas (> 650 mm/year), where species richness increased by 27% for mammals and 40% for birds in the most pyrodiverse regions. Range‐restricted birds were most increased by pyrodiversity, suggesting the diversity of fire regimes increases the availability of rare niches. Our findings are significant because they explain the conflicting results found in previous studies of savannas. We argue that managing savanna landscapes to increase pyrodiversity is especially important in wet savannas.

Pyrodiversity, which describes fire variability over space and time, is believed to increase habitat heterogeneity and thereby promote biodiversity. However, to date there is no standardised metric for quantifying pyrodiversity, and so broad geographic patterns and drivers of pyrodiversity remain unexplored. We present the first generalizable method to quantify pyrodiversity, and use it to address the fundamental questions of what drives pyrodiversity, which fire attributes constrain pyrodiversity under different conditions, and whether pyrodiversity is spatial grain-dependent. We linked the MODIS burned area and active fire products to measure fire size, seasonal timing, return interval, and intensity for 2.2 million individual fires in sub-Saharan Africa from 2000–2015. We then quantified pyrodiversity as a four-dimensional hypervolume described by fire attributes within a grid cell, for any spatial grain of analysis. Environmental (rainfall, vegetation, soils, and topography) and human-associated (cattle biomass, cropland area, and human population density) variables were assessed as potential drivers of pyrodiversity. Rainfall was the main environmental driver of pyrodiversity, with higher pyrodiversity in drier regions (< 650 mm yr-1). Pyrodiversity was not strongly associated with human-associated variables across Africa. Rainfall and a human influence index had clear but contrasting effects on the variability of fire size, seasonal timing, return interval, and intensity. Our analyses show that fire size and seasonal timing constrain pyrodiversity in wetter regions, whereas none of the fire attributes pose a strong constraint in drier regions. We found no evidence that pyrodiversity was spatial grain-dependent when recalculated at 5-minute grain increments from 15 to 120 minutes. We hypothesise that the strongest positive effect of pyrodiversity on biodiversity in all its forms will occur at intermediate precipitation (650–1300 mm yr-1), where fire plays an important role in shaping vegetation structure and where pyrodiversity is still quite high. This article is protected by copyright. All rights reserved.

AbstractThe Critically Endangered hirola Beatragus hunteri exists in two populations, a natural population on the Kenyan–Somali border and a translocated population in Tsavo East National Park, Kenya. The Tsavo population is becoming increasingly important for the survival of the hirola yet its status is unknown and little is understood about the factors that limit its growth. Here we report the size, distribution and demographic parameters of the Tsavo population of hirola and consider whether insufficient suitable habitat could be limiting its growth. The Tsavo population has not increased since 2000, when the last census was carried out, but neither has it significantly decreased. The importance of habitat as a limiting factor is dependent on the hirola's ability to utilize marginal habitat.