Premium
Altitudinal variation of leaf carbon isotope for Dendrosenecio keniensis and Lobelia gregoriana in Mount Kenya alpine zone
Author(s) -
Waigwa Antony Njogu,
Mwangi Brian Njoroge,
Gituru Robert Wahiti,
Omengo Fred,
Zhou Yadong,
Wang Qingfeng
Publication year - 2021
Publication title -
biotropica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.813
H-Index - 96
eISSN - 1744-7429
pISSN - 0006-3606
DOI - 10.1111/btp.12990
Subject(s) - altitude (triangle) , abiotic component , specific leaf area , water use efficiency , botany , horticulture , leaflet (botany) , effects of high altitude on humans , δ13c , precipitation , vapour pressure deficit , biology , stable isotope ratio , atmospheric sciences , ecology , photosynthesis , transpiration , geography , geology , geometry , mathematics , physics , quantum mechanics , meteorology , anatomy
Abiotic factors vary along altitudinal gradients, and this may influence plant morphology, physiology and function. This study aimed to test the hypothesis that leaf δ 13 C—a common proxy for water use efficiency—was indirectly influenced by morphological adjustments with changing climatic factors along an altitudinal gradient on Mount Kenya. We sampled leaves of Dendrosenecio keniensis and Lobelia gregoriana using seventy‐two 10 × 10 m plots situated every 100 m starting from 3600 to 4300 m. We determined leaf δ 13 C using stable isotope mass spectrometry. We also quantified the following morphological factors; leaf area, leaf mass per area, specific leaf area and leaf thickness. Climate data included mean annual temperature and precipitation, diurnal temperature range and water vapor pressure. Our results revealed that there was a leaf δ 13 C enrichment of 1.76 ‰ km −1 and 1.62 ‰ km −1 with altitude for D . keniensis and L . gregoriana , respectively. Leaf δ 13 C was enrichment by 0.01 ‰ mm −1 with mean annual precipitation along the altitude gradient for D . keniensis and 0.02 ‰ mm −1 for L . gregoriana . D . keniensis and L . gregoriana have high‐water use efficiency, an adaptation for surviving near freezing alpine temperatures and high‐diurnal range. Leaf δ 13 C exhibited a depletion of −0.37 ‰ per °C increase of mean annual temperature along the altitude gradient for D . keniensis and −0.34 ‰ per °C increase for L . gregoriana . Our results also showed a negative relationship between pCO 2 and leaf δ 13 C and positive relationship between pCO 2 and ∆ 13 C for both species. Low temperatures led to the increase in leaf thickness and specific leaf area for these two species, factors that influenced leaf δ 13 C and ∆ 13 C. Abstract in Chinese is available with online material.