The antiquity of Madagascar’s grasslands and the rise of C<sub>4</sub> grassy biomes

Bond, William J.; Silander, John A.; Ranaivonasy, Jeannin; Ratsirarson, Joelisoa

doi:10.1111/j.1365-2699.2008.01923.x

Cited by 154 publications

(203 citation statements)

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“…Bond et al [76] explored the question of whether Madagascan grasslands are ancient or, as has long been argued, products of deforestation in the 2000-4500 years since people settled the island. They argued that if the grasslands were secondary they would be expected to have low diversity, few if any open-habitat specialists, and low species turnover across environmental gradients.…”

Section: (A) Diversity and Endemismmentioning

confidence: 99%

The deforestation story: testing for anthropogenic origins of Africa's flammable grassy biomes

Bond

Zaloumis

2016

Phil. Trans. R. Soc. B

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Africa has the most extensive C4 grassy biomes of any continent. They are highly flammable accounting for greater than 70% of the world's burnt area. Much of Africa's savannas and grasslands occur in climates warm enough and wet enough to support closed forests. The combination of open grassy systems and the frequent fires they support have long been interpreted as anthropogenic artefacts caused by humans igniting frequent fires. True grasslands, it was believed, would be restricted to climates too dry or too cold to support closed woody vegetation. The idea that higher-rainfall savannas are anthropogenic and that fires are of human origin has led to initiatives to 'reforest' Africa's open grassy systems paid for by carbon credits under the assumption that the net effect of converting these system to forests would sequester carbon, reduce greenhouse gases and mitigate global warming. This paper reviews evidence for the antiquity of African grassy ecosystems and for the fires that they sustain. Africa's grassy biomes and the fires that maintain them are ancient and there is no support for the idea that humans caused large-scale deforestation. Indicators of old-growth grasslands are described. These can help distinguish secondary grasslands suitable for reforestation from ancient grasslands that should not be afforested.This article is part of the themed issue 'The interaction of fire and mankind'.

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Section: (A) Diversity and Endemismmentioning

confidence: 99%

The deforestation story: testing for anthropogenic origins of Africa's flammable grassy biomes

Bond

Zaloumis

2016

Phil. Trans. R. Soc. B

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“…This is particularly true of assumptions related to burning regimes, particularly in grassland ecosystems (see, for example, Foster and Motzkin, 2003;Maxwell, 2004). A number of recent studies have indicated that in regions that climatically should be able to support trees (e.g., S. Africa and Madagascar), there is a tendency to assume that all grasslands are a consequence of previous anthropogenic activity (Bond et al, 2008). By the classification of grasslands as "anthropogenic" they often acquire the label of a "degraded" landscape and therefore are of little conservation priority.…”

Section: Which Ecological Processes Are Important For Maintaining Tarmentioning

confidence: 99%

Questions of importance to the conservation of biological diversity: answers from the past

Willis

Bhagwat

2010

Clim. Past

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Abstract. Paleoecological records are replete with examples of biotic responses to past climate change and human impact, but how can we use these records in the conservation of current and future biodiversity? A recently published list of (One Hundred Questions of Importance to the Conservation of Global Biological Diversity) (Sutherland et al., 2009) highlights a number of key research questions that need a temporal perspective. Many of these questions are related to the determination of ecological processes in order to assess ecosystem function and services, climate changeintegrated conservation strategies, and ecosystem management and restoration. However, it is noticeable that not a single contributor to this list was from the paleo-research community and that extremely few paleo-records are ever used in the development of terrestrial conservation management plans. This lack of dialogue between conservationists and the paleo-community is partially driven by a perception that the data provided by paleoecological records are purely descriptive and not of relevance to the day-to-day management and conservation of biological diversity. This paper illustrates, through a series of case-studies, how long-term ecological records (>50 years) can provide a test of predictions and assumptions of ecological processes that are directly relevant to management strategies necessary to retain biological diversity in a changing climate. This discussion paper includes information on diversity baselines, thresholds, resilience, and restoration of ecological processes.

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“…In many parts of the world there remains considerable controversy as to whether savannas are the result of anthropogenic fire-activity or arise independent of human fireuse (Willis et al 2008;Bowman and Haberle 2010;McWethy et al 2010), with some authors arguing that plant and animal species diversity can be used as evidence against human agency (Bond et al 2008;Foreman 2016). In the case of Tasmanian sedgelands the diverse, and in some cases endemic, vascular (Corbett and Balmer 2007;Lawrence et al 2007) and non-vascular (Kantvilas 2007) flora and vertebrate (Driessen 2007) and invertebrate (Driessen et al 2014) fauna points to an ancient ecosystem that preceded human colonisation in the late-Pleistocene.…”

Section: Simulation Model Experimentsmentioning

confidence: 99%

Soil or fire: what causes treeless sedgelands in Tasmanian wet forests?

Bowman

Perry

2017

Plant Soil

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Background Ecologists fiercely debate the role of soil conditions and fire regimes in controlling forest -savanna boundaries. A prominent component of this debate centres on the plausibility and existence of fire-mediated alternative stable state dynamics (FMASS), a model first proposed by the Tasmanian ecologist WD Jackson in 1968. The FMASS model asserts that increased or decreased landscape fire activity, often due to human intervention, can overwhelm physical environmental (e.g. topography and edaphic factors) controls of forest and savanna mosaics, thereby creating landscape dynamism. Many FMASS models include fire-vegetation-soil interactions (FVS), in which changes in fire frequency can change soil fertility and hence tree growth. This interaction, in turn, affects the capacity offorests to recover from disturbance and long unburnt savanna to convert to forest. Scope We evaluate support for the FMASS-FVS model in the context of the dynamics of the Tasmanian forests that have recently been drawn into wider, global debates surrounding the cooccurrence of tree and treeless vegetation states. We develop a simple spatial simulation model to illuminate the difficulties in analysing landscape pattern to draw inferences about the existence of FMASS-FVS. Conclusions Our review of the Tasmanian evidence shows that FMASS-FVS cannot unambiguously explain all tracts of sedgelands in Tasmanian wet forests, and hence Tasmania should not be used as an exemplar of these theories globally. Our simulations highlight that soil sampling that targets forest boundaries risks erroneously concluding that the distribution of forest and savanna boundaries is decoupled from edaphic factors. We describe a structured methodological pathway that can identify the role of FMASS-FVS in Tasmanian forest dynamics, and elsewhere in the world. This approach use cross-scale temporal and spatial analyses, and targeted experimental tests, to illuminate the interplay of fire, vegetation and edaphic factors in controlling tree establishment and growth and forest boundary dynamics.

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The antiquity of Madagascar’s grasslands and the rise of C₄ grassy biomes

Cited by 154 publications

References 55 publications

The deforestation story: testing for anthropogenic origins of Africa's flammable grassy biomes

The deforestation story: testing for anthropogenic origins of Africa's flammable grassy biomes

Questions of importance to the conservation of biological diversity: answers from the past

Soil or fire: what causes treeless sedgelands in Tasmanian wet forests?

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The antiquity of Madagascar’s grasslands and the rise of C4 grassy biomes

Cited by 154 publications

References 55 publications

The deforestation story: testing for anthropogenic origins of Africa's flammable grassy biomes

The deforestation story: testing for anthropogenic origins of Africa's flammable grassy biomes

Questions of importance to the conservation of biological diversity: answers from the past

Soil or fire: what causes treeless sedgelands in Tasmanian wet forests?

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The antiquity of Madagascar’s grasslands and the rise of C₄ grassy biomes