Plants in dry landscapes have surprising diversity

Plants are the survivors of nature, equipped with a remarkable ability to cope with diverse climatic conditions. Their resilience against weather extremes and grazing pressure offers rich insights about biodiversity and the future of dryland ecosystems.

Even more intriguing is the fact that such resilient traits, which help plants thrive in dry landscapes, are not as uncommon as one might presume.

Puzzling phenomenon of plant traits

An international team of scientists led by Fernando Maestre of the King Abdullah University of Science and Technology (KAUST) delved into the fascinating world of plant traits and their response to changes in aridness and grazing pressure across global drylands.

Surprisingly, the researchers found that as aridity and grazing pressure increased, plant diversity did not decrease as expected.

Instead, the diversity of traits, particularly those linked to nutrient cycling, rose notably above an aridity threshold of 0.7, which marks the transition between semi-arid and arid zones. This increase in diversity was consistent with elevated grazing pressure.

Maestre, who was at the helm of this revolutionary study termed BIODESERT, noted that global initiatives aiming to describe plant trait diversity have focused on plant morphology and leaf carbon economy, but neglected the diversity of chemical elements that sustain plant survival and growth.

Plant survival strategies in dry landscapes

The research team conducted a thorough field survey to analyze the implications of aridity and grazing pressure on plant traits. They selected 98 sites from 25 countries, representing a global aridity gradient. Their selection included several plots spanning local gradients of grazing pressure.

The findings of the study were eye-opening. Variations in functional traits highlighted shifts in plant adaptation strategies under changing environmental conditions.

Similarly, the researchers noticed that aridity and grazing triggered a plethora of strategies to endure water shortage and grazing.

The team measured traits associated with the concentration of 14 chemical elements in leaves, leaf and plant size, and the leaf carbon economy.

This invaluable data sheds light on how aridity and grazing shape the co-variations and trade-offs observed among multiple morphological and chemical plant traits across dry landscapes.

Defying nature’s rule book

With rising levels of aridity, plants exhibited contrasting strategies. Some were tall species with fast-growing leaves following stress-avoidance strategies, and others were small conservative species following stress-tolerance strategies. The experts also noticed variations in Mg-Ca and Zn-Na concentrations in the leaves.

“These elemental strategies can reflect the contrasting role of chemical elements in plants, either as a way to tolerate high aridity levels or as base elements for defensive compounds against grazers,” noted Maestre.

Redefining plant phenotypic diversity

The study provides novel insights into how vascular plants react to biotic stressors and environmental extremes.

More than half of the trait diversity was observed in the most arid and grazed drylands, highlighting the unique nature of these harsh environments. Contrary to popular belief, harsh environmental conditions did not reduce plant trait diversity.

“Our results also highlight the importance of considering a plant’s chemical composition (the elementone) to understand dryland biodiversity responses to ongoing climate change,” said Maestre.

“Plants could have many alternative strategies to cope with increases in environmental stress induced by climate change and land-use intensification.”

Maestre plans to expand the BIODESERT survey into the arid and hyper-arid ecosystems of Saudi Arabia. His research offers valuable insights into how Saudi plant diversity can respond to ongoing climate change and also aids the selection of species suitable for ongoing and future greening programs.

The research confirms that plants are far from fragile, devising astounding strategies to survive and thrive in the harshest of conditions.

The role of conservation in arid ecosystems

Understanding plant diversity in arid terrains highlights the urgent need for conservation efforts to protect these unique ecosystems. Climate change poses significant threats, making proactive measures essential to preserve resilient plant species.

Conservation should focus on safeguarding habitats from land degradation, overgrazing, and unsustainable agriculture, while also restoring degraded landscapes to enhance biodiversity.

Involving local communities and incorporating Indigenous knowledge can create a collaborative approach to land management.

Promoting research and monitoring programs will ensure ongoing understanding of plant adaptation, enabling targeted conservation strategies.

By recognizing the importance of these efforts, we can help sustain the resilient plant species that thrive in the harshest climates.

The study is published in the journal Nature.

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