Morphological and physiological responses to aridity in narrowly- and widely-distributed plant species in drylands

This study was recently reported by Jianming Deng’s group from the State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University. Over the past decade, Deng’s team has established a natural transect spanning nearly 4,000 kilometers from east to west, encompassing almost all ecosystem types in China’s drylands. A central aim of their research is to elucidate the adaptive strategies of dryland plants regarding plant functional traits. Although the past two decades have seen substantial progress in this field, most investigations have considered all species together, ignoring that species with different geographic ranges may respond differently to the environment. In particular, the adaptive strategies of narrow- and wide-ranging species have remained largely unknown.  Moreover, narrow-ranging species are at higher risk of extinction than wide-ranging species under global change. Therefore, understanding the adaptive strategies used by plants in drylands, especially narrow-ranging species, may help preserve these species.

Deng’s team collected datasets on 10 leaf functional traits, including morphological and physiological traits, from 152 plant species across drylands in China. All sampled species were classified as either narrow- or wide-ranging based on their distribution ranges at a global scale. Most of the leaf functional traits did not exhibit significant differences between narrow- and wide-ranging species, except that narrow-ranging species had higher leaf water content than wide-ranging species under high aridity.

The author also provided morphological evidence that narrow-ranging species possess higher leaf water content. In these species, leaf volume increased at a faster rate than leaf dry weight with increasing aridity compared to wide-ranging species (higher scaling exponent of leaf volume–leaf dry weight), indicating that their leaves had a relatively larger space for water storage. Importantly, species with higher leaf water content tended to be more abundant in narrow-ranging species at high aridity levels, where narrow-ranging species also occupied a larger proportion of the habitat compared to wide-ranging species. These results highlight leaf water content as a key functional trait underpinning the ecological success of narrow-ranging species in extremely arid environments, offering new insight into the trait-based mechanisms that shape species distributions along aridity gradients. They further underscore the importance of incorporating water-storage traits into conservation strategies, particularly for vulnerable, narrow-ranging species at heightened risk from ongoing climate-driven aridification.

 

See the article:

Morphological and Physiological Responses to Aridity in Narrowly- and Widely-distributed Plant Species in Drylands

 

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