The paradox of mesquite

Very few species possess the ability to thrive under extreme harsh conditions (drought, salinity, pollution etc.) as profoundly as Neltuma juliflora (mesquite). The species was introduced to the Indian subcontinent to provide ecosystem services such as greening drylands, combating soil erosion, and supplying fuelwood. At present, depending on who you ask, this thorny tree is either a resilient saviour or an ecological villain. Recent research on mesquite’s impacts in non-native landscapes reveals a nuanced truth: under the present ongoing and future climate instability and in human-altered systems, the idea of categorising Neltuma juliflora as purely ‘good’ or ‘bad’ no longer makes sense.  

It is quite impossible not to appreciate mesquite’s remarkable resilience.  In dry drought regions, where agriculture fails and soil erodes — mesquite thrives and survives under extreme conditions. It renders much needed ecosystem services such as firewood, carbon sequestration, pollination resources, and honey production. Also, in metal contaminated soils, mesquite phyto-remediates and enriches soil with essential nutrients. At a time when climate vagaries are pushing global landscapes towards desertification, this species can no longer be considered just a ‘notorious weed’; we need to look at it as a climate warrior, sequestering atmospheric carbon in its biomass / soil and fighting climate change

Despite the benefits, mesquite invasions have resulted in the displacement of native plants leading to biodiversity decline, which consequently affects the livelihood of pastoralists. Its sharp thorns can injure animals and restrict wildlife movement. Even worse, its dense monocultural canopy sucks out ground water, potentially worsening regional water crises.

Efforts to eradicate mesquite including physical, chemical and biological measures have largely failed. This reality raises a critical management dilemma: if mesquite cannot be completely eradicated, yet cannot be allowed to expand uncontrollably, what should be done? The most practical conclusion is that management must be context specific. Mesquite must be actively eliminated from forests, riparian zones, protected habitats and landscapes where biodiversity richness is irreplaceable. In contrast, in vulnerable, low biodiversity, arid and semi-arid human-dominated zones, mesquite coppices can be selectively retained to render positive ecosystem services (carbon sequestration). Controlled utilisation strategies — such as converting biomass to biochar or fuel wood — might help to control the coppices’ expansion while delivering socio-ecological benefits.

The conflict between human needs and global system balance is perhaps the most pressing dilemma of the 21st century. Mesquite may serve as a test case for adaptive management, where value of a species is largely determined by ecological functions within the context rather than by rigid labels such as “invasive” or “native”.

Mesquite forces humanity to confront an important truth: global ecosystems are dynamic, largely driven by global climate. The Sahara Desert was once a green savanna with full of hippos and elephants. Today, that same landscape exists as the world’s largest hot desert, reminding us that ecosystems are dynamic; species and landscapes continually evolve in response to global climate change.  Although mesquite was deliberately introduced by humans, its invasion may reflect the shift in ecosystem condition towards greater aridity. Under such dry conditions, the most adaptable species will survive dynamic changes in environment. Rather than categorising mesquite as simply good or bad, we must focus on where it must be removed, how its invasion can be controlled, how its terrestrial biomass can be leveraged / monetised. Answers to these questions may help us manage a rapidly changing planet. 

R V Akil Prasath is a researcher (PhD student) at Bharathidasan University in Tiruchirappalli specialising in botany, invasion/restoration ecology, Environment Impact Assessment and environmental biogeo chemistry

Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth