Functional groups based on leaf physiology: are they spatially and temporally robust?

Area of Science:

• Ecology
• Plant Physiology

Background:

• Ecosystem complexity can be simplified by grouping species with similar functional traits.
• Florida scrub habitat is a fire-maintained ecosystem crucial for understanding plant community dynamics.

Purpose of the Study:

• To test the functional grouping concept in Florida scrub habitats.
• To identify physiologically based functional groups and assess their robustness.
• To evaluate morphological characteristics as practical indicators for these functional groups.

Main Methods:

• Species functional groups were identified using gas exchange measurements and integrated functional measures (e.g., %N, delta13C, delta15N, C:N ratio).
• Cluster analysis and Analysis of Similarities (ANOSIM) were used to identify and test the distinctness of functional groups.
• Morphological characteristics (life form, leaf thickness, specific leaf area) were compared to physiological groupings.

Main Results:

• Five distinct physiologically based functional groups were identified in fire-maintained Florida scrub.
• These functional groups remained robust across spatial, temporal, and management variations (prescribed burn, mechanical treatment, fire suppression).
• Life form classification, particularly when including parasitic plants, effectively represented the physiological functional groups, outperforming specific leaf area and leaf thickness.

Conclusions:

• The functional grouping concept is applicable to Florida scrub ecosystems.
• Physiologically based functional groups are stable across environmental and management gradients.
• Life form classification offers a practical method for scaling physiological processes to the ecosystem level for modeling purposes.