Leaf patterns, leaf size and ecologically related traits in high Mediterranean mountain on the Moroccan High Atlas

Abstract

Leaf traits functional relationship is particularly important in plant ecological strategies, but few data are available from Mediterranean high-altitude environments. We analysed leaf general patterns and leaf trait relationships in 84 perennial species on the High Atlas, Morocco. We examined the correlation amongst leaf size, leaf width and length, plant height and seed size, analysed multi-trait relationships using Structural Equation Models and tested leaf size variation amongst growth forms (functional groups). Species spanned 103 range of leaf size (sub-lepto- to microphylls). Nanophylls (48.8%) were dominant and over-represented in half-shrubs. Tree and rosette herbs were more likely to have large leaf size (nano-micro- and microphylls), whereas shrubs have medium leaf size (nano-micro- and nanophylls) and cushion and half-shrubs have small (sub-lepto- to nanophylls) and narrow leaves. Small-leaved species synchronized their leaf phenological activity with the dry summer months (May–August), and large-leaved species extended throughout the spring until the end of summer following the similar patterns found in lowland Mediterranean environments. Regarding woody species, our results showed a positive and significant relationship between leaf size and plant height and a non-significant relationship between leaf size and seed size. Structural Equation Models showed that variation in leaf size was triggered chiefly by changes in leaf form (leaf width) and plant height, seed size being of no relevance. In our study area, large-seeded species have a relatively wide range of leaf size. The hypothesis that the combination of large seeds and small leaves is allometrically unlikely (except for leptophyll Conifers) was supported in this study.