{"id":2190658,"date":"2026-04-07T18:00:41","date_gmt":"2026-04-07T16:00:41","guid":{"rendered":"https:\/\/focusingonwildlife.com\/news\/?p=2190658"},"modified":"2026-04-02T14:38:10","modified_gmt":"2026-04-02T12:38:10","slug":"an-invasive-guava-is-muscling-out-madagascars-forests-and-lemurs-are-helping","status":"publish","type":"post","link":"https:\/\/focusingonwildlife.com\/news\/an-invasive-guava-is-muscling-out-madagascars-forests-and-lemurs-are-helping\/","title":{"rendered":"An invasive guava is muscling out Madagascar\u2019s forests \u2014 and lemurs are helping"},"content":{"rendered":"

Madagascar is renowned for its lemurs, which are threatened due to hunting and deforestation. Restoring native forests to ensure their survival is critical, but once damaged, forests in Madagascar are vulnerable to takeover by invasive guava trees \u2014 whose seeds the lemurs themselves are helping to spread.<\/p>\n

When the delicious strawberry guavas (Psidium cattleyanum<\/i>) are in fruit, lemurs will choose them over native fruit, says Amy Dunham, a biologist at Rice University in the U.S.<\/p>\n

On her last visit to Ranomafana National Park, in southeastern Madagascar, Dunham, who has been doing fieldwork there for more than 30 years, filmed an endangered Milne-Edwards\u2019 sifaka (Propithecus edwardsi<\/i>), a large lemur with a dark-brown and cream-colored coat, a black hairless face, and penetrating orange eyes. The sifaka was sitting in a thick guava patch munching on one of the ruby-red fruits.<\/p>\n

\u201cFor me, [the video] captures a big part of the picture,\u201d Dunham says. \u201cAn endangered lemur can benefit from an invasive plant that is simultaneously undermining the long-term biodiversity and functioning of the forest.\u201d<\/p>\n

Dunham and colleagues\u00a0carried out a study\u00a0in Ranomafana in 2024 that found that where strawberry guavas, originally from Brazil, had taken hold, they created thick, impenetrable patches in areas of forest that had been disturbed as far back as the 1930s. These thickets, which Dunham refers to as \u201cmonocultures,\u201d drain key nutrients from the soil, suppress the growth of native plants, and strip away the diversity of insects and other invertebrates.<\/p>\n

The loss of insect diversity means native animals are robbed of an essential source of protein. Not just lemurs, but also birds and tenrecs, a group of mammals, some of them resembling hedgehogs, that evolved in Madagascar and depend on insects for a large portion of their diet.<\/p>\n

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A lemur eating a strawberry guava. Image courtesy of Natalee Phelps.<\/figcaption><\/figure>
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Cartoon by Julieanne Montaquila\/Rice University<\/figcaption><\/figure>
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Outcompeting native trees<\/b><\/h2>\n

Although it\u2019s still unclear whether guavas pose as big a threat to parts of the forest that are still intact, if a tree does happen to fall \u2014 say, during a cyclone \u2014 guava seeds deposited in that part of the forest via lemur dung could germinate and quickly fill the gap by outcompeting native plants in the new clearing.<\/p>\n

\u201cWe often think about the lemurs, but not all the rest of the biodiversity in those forests,\u201d Dunham says. Madagascar is \u201cone of the hottest hotspots for plant diversity,\u201d she adds, and that diversity is as important to protect and preserve as the lemurs, whose own survival depends upon it.<\/p>\n

Take mistletoes. At least 16 different species of these epiphytic plants grow high up in the forest canopy in undisturbed parts of Ranomafana, clinging to the branches of native trees. The mistletoes, known in Malagasy as\u00a0tongoalahy<\/i>, in turn provide leaves, fruit and flowers that lemurs and a host of other animals feed on.<\/p>\n

In a separate study led by Malagasy ecologist Zo Fenosoa, and co-authored by Dunham, the team staked out sites in Ranomafana where three different species of mistletoes grow, and watched as 30 different species of birds, and seven different species of lemurs visited them. Some ate the fruits, others the nectar or the leaves; others foraged on the insects attracted to the plants.<\/p>\n

Among those that ate the fruit were nocturnal brown mouse lemurs (Microcebus rufus<\/i>) and Crossley\u2019s dwarf lemurs (Cheirogaleus crossleyi<\/i>); and by day, lesser vasa parrots (Coracopsis nigra<\/i>), Madagascar blue-pigeons (Alectroenas madagascariensis<\/i>) and Malagasy bulbuls (Hypsipetes madagascariensis<\/i>).<\/p>\n

Mistletoes are \u201ckeystone resources,\u201d the study found, sustaining all of these species while also providing a staple food source for larger sifaka lemurs in times of food scarcity.<\/p>\n

In guava-invaded patches, however, there are no mistletoes. Guava stems and branches shed their bark, depriving the sticky mistletoe seeds of a secure place to latch onto and grow.<\/p>\n

Since the 1950s, large areas of Madagascar\u2019s native forests have been lost to or degraded by agriculture and timber extraction. The island still loses an\u00a0estimated\u00a0200,000 hectares (nearly 500,000 acres) annually. This leaves the way open for the spread of strawberry guavas.<\/p>\n

Even if guava roots are successfully removed from forest restoration sites, their fallen leaves and fruit leave behind allelochemicals in the soil that are toxic to other plants.<\/p>\n

\u201cIf guava dominates [forest] regeneration,\u201d Dunham says, \u201cwe risk rebuilding forests that are structurally and ecologically simplified, with fewer resources for native species.\u201d<\/p>\n

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Strawberry guavas create thick, impenetrable patches in disturbed patches of forest. Image courtesy of Amy Dunham\/Rice University.<\/figcaption><\/figure>
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Biochar a potential solution<\/b><\/h2>\n

There could be a solution. On the Indian Ocean island of Mauritius, more than 1,000 kilometers (600 miles) east of Madagascar, strawberry guavas are also threatening remnant native forest patches. But in 2017, at sites in Black River Gorges National Park, a team led by Mauritian ecologist Lutchmee Sujeeun\u00a0found that spreading biochar, a soil-boosting charcoal made from plant waste, in areas where guava trees had been removed reduced the effects of the guava allelochemicals and promoted the growth of native plants.<\/p>\n

The biochar Sujeeun used was made from coconut husks; if it were ever to be scaled up, an obvious source would be the cut stems of the guava trees themselves.<\/p>\n

However, she cautions that the dosages of biochar needed, and the effects it has on native plants and animals, as well as on different soil types, still need to be thoroughly assessed. Biochar\u2019s application at scale, whether in Madagascar or Mauritius, would prove costly and labor-intensive, combined as it would be with the physical removal of the guava trees.<\/p>\n

\u201cThe best option is to identify areas and species that are most likely to show large positive responses to biochar applications,\u201d Sujeeun says.<\/p>\n

Anthropologist Cortni Borgerson, an associate professor at Montclair State University in the U.S., who wasn\u2019t part of Dunham\u2019s guava study in Ranomafana, says vulnerable brown lemurs (Eulemur fulvus<\/i>) love strawberry guavas so much that hunters even use the fruit to bait traps set for them along a central part of the island\u2019s eastern coastal region.<\/p>\n

\u201cLike the bait in a trap, the guava lures Madagascar\u2019s remaining frugivores to endanger the very forests on which they depend,\u201d Borgerson tells Mongabay in an email from Masoala National Park, in the northeast of the island.<\/p>\n

\u201cThe key to long-term resilience [of Madagascar\u2019s native ecosystems] lies in restoring that extraordinary biodiversity, starting with native plants,\u201d she adds. \u201cIt will take a massive effort to remove this invasive species, but dedicated, passionate people like the authors of [the guava] study are producing the exact science we need to make a difference.\u201d<\/p>\n

Citations:<\/b><\/h2>\n

McCary, M. A., Fenosoa, Z. S., Montaquila, J., Wuesthoff, E. F., Rajeriarison, E., Matsuda, E., & Dunham, A. E. (2026). Invasive strawberry guava (Psidium cattleyanum<\/i>) disrupts forest recovery and invertebrate biodiversity in Madagascar\u2019s threatened rainforest ecosystem.\u00a0Biological Conservation<\/i>,\u00a0315<\/i>, 111703. doi:10.1016\/j.biocon.2026.111703<\/a><\/p>\n

Fenosoa, Z. S. E., Razafindratsima, O., Rakotomanana, H., Razafindraibe, H., Rasamisoa, D., & Dunham, A. (2020). Birds and lemurs as potential seed dispersers of mistletoe in Madagascar\u2019s rain forests.\u00a0Recherches Pour le Development<\/i>,\u00a028<\/i>, 49-63. Retrieved from\u00a0http:\/\/cidst.recherches.gov.mg\/IMG\/doc\/SB_28_TI.pdf#page=49<\/a><\/p>\n

Sujeeun, L., & Thomas, S. C. (2022). Biochar rescues native trees in the biodiversity hotspot of Mauritius.\u00a0Forests<\/i>,\u00a013<\/i>(2), 277. doi:10.3390\/f13020277<\/a><\/p>\n

This article<\/a> by Ryan Truscott was first published by Mongabay on 31 March 2026. Lead Image: A lemur eating a strawberry guava. Image courtesy of Natalee Phelps.<\/i><\/p>\n

What you can do<\/h2>\n

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