Morpho-Physiological Traits and Dehydration Tolerance of High-Altitude Andean Wetland Vegetation in the Chilean Atacama Region.

Abstract

High-altitude wetlands of the Andes (HAWA) are unique ecosystems influenced by substrate conditions and reliant on consistent water supply from precipitation, runoff, groundwater, and glacial melting. Considering the diverse ecosystem services provided by HAWAs and the increasing threat these ecosystems face from natural and anthropogenic factors, such as drought, land-use change, and climate change, it is crucial to conduct a comprehensive assessment of their vulnerability. In this study, we characterized the functional trait spectrum of dominant plant species within the Salar de Pedernales, Quebrada Leoncito (Leoncito) and Río Negro HAWAs and explored the relationships between these traits and key environmental variables. Our results revealed significant variation in plant species based on traits such as leaf dry matter content (LDMC), specific leaf area (SLA), relative water content (%RWC), and leaf thickness. Species were primarily differentiated by LDMC and SLA. Plants from Salar de Pedernales had higher δ13C values, indicating higher water-use efficiency (WUE) compared to those in tributaries like Leoncito and Río Negro. A positive correlation between stomatal conductance and CO₂ assimilation was found, with the Salar de Pedernales plants showing high WUE despite these plants exhibiting similar photosynthetic rates. Foliar nitrogen percentage and δ¹⁵N values indicated nitrogen availability could be influenced by microbial activity and salinity levels. Higher salinity in the Salar de Pedernales may inhibit microbial activity, resulting in higher δ¹⁵N values. At the community level, decreased SLA correlated with higher δ¹³C values, suggesting less carbon discrimination and higher WUE in the Salar de Pedernales plants. While HAWA plant species have adapted to their environment, their limited dehydration tolerance makes them vulnerable to future hydrological changes. Understanding these responses forms a basis to develop effective conservation and management strategies for HAWAs.