Environmental ranges discriminating between macrophytes groups in European rivers

Area of Science:

• Ecology
• Botany
• Environmental Science

Background:

• Riverine macrophytes are key indicators of aquatic ecosystem health.
• Species distribution is influenced by environmental gradients, but quantitative data on discriminatory ranges are scarce.
• Existing knowledge often relies on expert judgment, limiting predictive capabilities.

Purpose of the Study:

• To quantitatively estimate the environmental ranges discriminating between distinct riverine macrophyte groups.
• To provide a data-driven approach for predicting ecosystem characteristics based on macrophyte assemblages.
• To validate findings against existing literature and assess their applicability at various scales.

Main Methods:

• Utilized a pan-European dataset of riverine macrophyte surveys from 22 countries.
• Employed cluster analysis to identify four distinct macrophyte species groups based on co-occurrences.
• Applied Random Forest models to estimate discriminatory ranges for key environmental variables (e.g., total phosphorus, nitrate, flow velocity).

Main Results:

• Identified four macrophyte groups: mosses, pioneer species, emergent/floating species, and eutraphent species.
• Quantitatively estimated discriminatory ranges for environmental variables, including total phosphorus (100-150 μg L⁻¹), nitrate (0.5-20 mg L⁻¹), and flow velocity (0.05-0.70 m s⁻¹).
• Mosses correlated with coarse substrates, while vascular plants were associated with finer sediments.

Conclusions:

• The study provides the first quantitative approximation of environmental discriminatory ranges for European riverine macrophyte groups using a large dataset.
• These findings offer generalizable patterns applicable for regional and local river ecosystem assessment and management.
• The results support and refine existing ecological knowledge on macrophyte-environment relationships.