Sally Archibald

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Theoretically, fire-tree cover feedbacks can maintain savanna and forest as alternative stable states. However, the global extent of fire-driven discontinuities in tree cover is unknown, especially accounting for seasonality and soils. We use tree cover, climate, fire, and soils data sets to show that tree cover is globally discontinuous. Climate influences(More)
• We aimed to identify the limits of savanna across Africa, Australia and South America. We based our investigation on the rich history of hypotheses previously examined: that the limits of savanna are variously determined by rainfall, rainfall seasonality, soil fertility and disturbance. • We categorized vegetation on all continents as 'savanna' (open(More)
Savannas are known as ecosystems with tree cover below climate-defined equilibrium values. However, a predictive framework for understanding constraints on tree cover is lacking. We present (a) a spatially extensive analysis of tree cover and fire distribution in sub-Saharan Africa, and (b) a model, based on empirical results, demonstrating that savanna and(More)
Fire is a ubiquitous component of the Earth system that is poorly understood. To date, a global-scale understanding of fire is largely limited to the annual extent of burning as detected by satellites. This is problematic because fire is multidimensional, and focus on a single metric belies its complexity and importance within the Earth system. To address(More)
Human ability to manipulate fire and the landscape has increased over evolutionary time, but the impact of this on fire regimes and consequences for biodiversity and biogeochemistry are hotly debated. Reconstructing historical changes in human-derived fire regimes empirically is challenging, but information is available on the timing of key human(More)
Ecologists have long sought to understand the factors controlling the structure of savanna vegetation. Using data from 2154 sites in savannas across Africa, Australia, and South America, we found that increasing moisture availability drives increases in fire and tree basal area, whereas fire reduces tree basal area. However, among continents, the magnitude(More)
An algorithm for identifying individual fires from the Modis burned area data product is introduced for southern Africa. This algorithm gives the date of burning, size of fire, and location of the centroid for all fires identified over 8 years in Africa south of the equator. The results are compared with other available spatial information on fires, and(More)
Drivers of interannual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa S. Archibald, A. Kirton, M. van der Merwe, R. J. Scholes, C. A. Williams, and N. Hanan CSIR Natural Resources and Environment, P.O. Box 395 Pretoria 0001 South Africa School of Geography, Clark University, USA Natural Resources Ecology Lab, Colorado(More)
Human impacts on fire regimes accumulated slowly with the evolution of modern humans able to ignite fires and manipulate landscapes. Today, myriad voices aim to influence fire in grassy ecosystems to different ends, and this is complicated by a colonial past focused on suppressing fire and preventing human ignitions. Here, I review available evidence on the(More)
L. Merbold, J. Ardö, A. Arneth, R. J. Scholes, Y. Nouvellon, A. de Grandcourt, S. Archibald, J. M. Bonnefond, N. Boulain, C. Bruemmer, N. Brueggemann, B. Cappelaere, E. Ceschia, H. A. M. El-Khidir, B. A. El-Tahir, U. Falk, J. Lloyd, L. Kergoat, V. Le Dantec, E. Mougin, M. Muchinda, M. M. Mukelabai, D. Ramier, O. Roupsard, F. Timouk, E. M. Veenendaal, and W.(More)