Thursday, November 23, 2023

Buffelgrass invasion in the ABC (and why people should be worried)

Clusters of Cenchrus ciliaris (buffelgrass) with whitish flowerheads in Aruba

To say that the southern Caribbean islands of Aruba, Bonaire, and Curacao (which are fondly called the ABC islands) have a somewhat small number of grass species would be accurate, and these include quite a few invasive species that are also prevalent in many other Caribbean countries.

During my visit to these islands last week, one of the more prominent invasives was Chloris barbata (subfamily Chloridoideae), its digitate inflorescence a common sight in disturbed areas. This species was present not only in the most urban of areas, but it popped up even close to the beaches.

Chloris barbata in Bonaire's Te Amo beach

But a more ominous invasive in the ABC is Cenchrus ciliaris (of the subfamily Panicoideae, syn. Pennisetum ciliare, aka buffelgrass in the USA), which has been notorious for its ongoing threat to the iconic Saguaro in the southwest USA. This species crowds out native vegetation, and because it exists in dense clusters, it can create continuous fuel sources for fires. Such fires are deadly to the Saguaro and other desert plants, which have not evolved to live through it.

Cenchrus ciliaris near Mambo Beach in Curacao 

C. ciliariis is from Africa and parts of the Middle East and Asia, and it was brought to the USA as a source of cattle forage and erosion control. It can tolerate arid conditions, and is thus a good fit in the semi arid environments of the ABC islands.

During a bus excursion around Aruba, I saw large fields of what I took to be this species beyond the main urban areas. But even in the very midst of the few towns that dotted these islands, I found C. ciliaris hiding in plain sight.

Cenchrus ciliaris in middle of road in Curacao

In Curacao, rows of this grass lined the canals emptying into Mambo Beach, and I even found it in the middle of a street in front of the Maritime History Museum!

The presence and continued proliferation of this species in the islands should be worrisome to authorities and to the inhabitants. The history of C. ciliaris in the American Southwest has demonstrated its ability to overwhelm native habitats, and the recent huge fires in Hawaii that killed hundreds is a warning about what can happen if people are surrounded by fire-prone invasive grasses. The fact that buffelgrass has been recorded as burning up to 871 °C, and indirectly recorded to temperatures of 900 °C. (MacDnald et al, 2013), is testament to its potential threat to the environment and people.

Masses of flowering C. ciliaris in Aruba

Hopefully, the authorities in the island have been taking steps to address this before it has the potential to become a major problem.

Literature cited

McDonald, C.J., McPherson, G.R. Creating Hotter Fires in the Sonoran Desert: Buffelgrass Produces Copious Fuels and High Fire Temperatures. fire ecol 9, 26–39 (2013).

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