Developing plant functional groups to identify changes in functional composition and diversity in a dryland river...

Area of Science:

• Ecology
• Hydrology
• Environmental Science

Background:

• Land use and climate change impact dryland stream flows, affecting ecological functioning.
• Increased surface water persistence due to altered hydrology is poorly understood, especially in previously ephemeral systems.

Purpose of the Study:

• Investigate relationships between hydrologic regimes and riverine plant traits/functional composition.
• Identify plant functional groups (FGs) and assess their distribution across hydrological gradients.
• Predict ecological shifts in response to changing flow regimes, particularly from mine water discharge.

Main Methods:

• Hierarchical clustering of 40 woody perennial species based on traits to identify seven FGs.
• Assessed FG abundance, functional composition, and richness along a 14 km gradient.
• Examined variation across persistent to ephemeral flow, groundwater depth, and stream distance gradients.

Main Results:

• Two dominant FGs identified: drought-avoidant mesic trees and drought-tolerant xeric shrubs.
• Mesic trees associated with shallow groundwater but had reduced cover near persistent flows.
• Higher FG and species richness observed closer to the mine discharge point, especially on the floodplain.

Conclusions:

• Mine water discharge significantly altered riverine ecosystem structure and function.
• Quantifying FG distribution is crucial for assessing impacts of mine water discharge.
• Findings inform post-mining restoration planning for riverine ecosystems.