Do afroalpine plants differ from other alpine plants by their leaf functional traits?

Afroalpine plants develop under specific climate with great daily fluctuations and weak seasonal dynamics of temperature. Do leaf functional traits of the plants in Mt. Kenya differ from those of temperate plants in NW Caucasus? To answer this question, we conducted a comparative study at the Teleki valley (4000–4500 m a.s.l.), Mt. Kenya, Kenya, and Teberda national park (2600–2900 m a.s.l.), the Caucasus, Russia. We measured leaf area, fresh and dry mass, C, N, P, δ13C, δ15N and derivative traits (specific leaf area – SLA, leaf dry matter content – LDMC, C:N and N:P ratios) for 48 species at the Teleki valley, and the same traits, except for the δ13C and δ15N, for 141 species in the Teberda national park. The CSR-strategies scores were calculated. We applied the Principal Component Analysis to reveal the main patterns of trait variation. Leaf dry mass of Mt. Kenya alpine plants ranged from 0.27 mg (Sagina afroalpina) to 14.0 g (Dendrosenecio keniodendron). Leaf area, mass and LDMC of alpine plants in both regions did not differ significantly. The SLA of Mt. Kenya’s plants varied about 20-fold: from 2.6 mm2 mg-1 (Festuca pilgeri) to 39.8 mm2 mg-1 (Cineraria deltoidea), and Caucasian plants had higher SLA. N and P leaf concentrations were higher, but C lower in Caucasian plants than in Kenyan. Leaf N:P ratio was similar for both regions, while C:N ratio was higher in Kenyan plants. Species of “rosette” trees (Dendrosenecio spp.) differed from other species by size characteristics (maximal leaf dry mass and area were in Dendrosenecio keniodendron), as well as correspondingly higher investment to mechanical tissues (high C:N ratio, low SLA). By the other functional traits, “rosette” trees were similar to many other alpine plants. Thus, afroalpine plants of Mt. Kenya are close to temperate alpine plants by some leaf functional traits, but possess higher stress-tolerance.