Trees threaten grasslands in Madagascar more than fire

Malagasy grasslands are often ignored, or worse, deplored. Biological research concentrates in the forests, many still shrinking despite conservation efforts. Yet research by plant ecologist Cédrique Solofondranohatra adds another layer of argument to the case that Malagasy grasslands have an ancient history and are important reservoirs of biodiversity themselves. Despite this, recent tree-planting efforts for climate change mitigation (of the ‘trillion trees‘ mode) often seem to take the easy path formed by a century of habit: planting exotic pines, acacias, and eucalypts in the grasslands, perceived as open, available, fire-damaged, and worthless. A much more laudable goal would be to restore trees to areas recently deforested.

A new look at Malagasy grasslands: researchers visit Ambohitantely

Three elements to this story: First, the grasslands. Cédrique’s recent paper argues that the grasses of Madagascar are ancient assemblages of species shaped by fire and megafaunal grazing – analagous to those in Africa – that would not be on the island had grasslands simply been a recent result of human burning and deforestation. Her work in turn builds on recent momentum from scholars investigating Malagasy grasslands (not so coincidentally, many are South African and accustomed to the idea of biodiverse fire-dependent grasslands).

Second, fire. For some Malagasy grasslands, “getting burned is in their DNA”, as reported by a Mongabay article about Cédrique’s work. Together with Caroline Lehmann, I recently wholly revised a chapter on fire in the Malagasy highlands for the forthcoming second edition of Steve Goodman’s Natural History of Madagascar. We review how people use fire, the effects of burning, and the history of fire management. We reviewed recent research, which suggests that several grassland communities that are adapted to lightning fires long predate human arrival in the highlands, but also argue that fire-grass-grazing interactions, historical and current, are vastly understudied on the island.

Third, trees. When someone says “plant trees” in Madagascar, the “go to” option, is putting eucalypts, acacias, and pines in the grasslands. This option has 120 years of path dependency: experience, institutions, nurseries, discourses. It works in places where people want to earn money from woodlots, like in the charcoal forests east of Antananarivo. Elsewhere, the strategy struggles in the face of recurrent fires. Where pines, acacias, and eucalypts do succeed in getting established, the grasslands are transformed through further invasion, shifting fire regimes as well. Most poignantly, plantations in grasslands are “pointless” from a carbon mitigation perspective, according to William Bond and colleagues in an article in TREE titled the trouble with trees“.

So, the conclusion for “trillion trees” enthusiasts is to be careful not to rush to plant pines, acacias, and eucalypts in possibly ancient grasslands, but to focus instead on restoring trees to recently deforested areas. Despite the path-dependent focus on exotic trees of some government agencies, several projects and NGOs have already taken up this challenge, as noted in a different Mongabay article “Madagascar’s bold reforestation goal lacks a coherent plan, experts say“. How such actions and decisions are justified, made, and contested, and who gains and loses in their implementation, is worthy of closer attention that I hope to investigate in future work.

It is exciting to re-engage with these issues – which occupied me in my own dissertation work two decades ago – and to see them advance. I thank Caroline Lehmann for the invitation to a grass-fire workshop and fieldtrip in Madagascar last year, from which the above photos come.

One Response to Trees threaten grasslands in Madagascar more than fire

  1. Christel Mattheeuws says:

    I lives in gassland Bezanano where the situation is the same.

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