Abstract:

To quantitatively characterize leaf trait variation and the manner that plants adapt to extremely dry climates, we measured four leaf functional traits, i.e., leaf mass per area (LMA), mass- and area-based leaf nitrogen concentration (N_mass, N_area) and leaf dry matter content (LDMC) for 110 plant species in Xinjiang Junggar Basin, NW China. Plant family, plant functional group and climatic factors (plant water availability: α; mean temperature of the warmest month: MTWA) were used as the dependent variables to explain the species-level variation in LDMC, LMA, N _mass, and N_area. The plot-level leaf trait values were related to α and MTWA via stepwise regression. Our results indicated that: (1) the species-level leaf trait variations are to large extent determined by plant family, while the influence of functional group and climatic factor tends to be the second; (2) At the plot-level, LMA increases as the climate becomes drier, while N _mass is positively related to the simultaneous optimization of α and MTWA, i.e., N _masstends to be higher in warm-wet habitats than in cold-dry one. LDMC and N_mass are less relevant to the climatic gradient. Plants in the study area have demonstrated an overall adaptation to the extremely dry climate. However, due to the differences in phylogenic background, different species may take different strategies in the face of the same climatic gradient. It is therefore important to examine the relative importance of plant phylogenic background and the environments on plant trait variation, which may matter for our prediction of plant response to the environmental changes in arid area.

Key words: leaf nitrogen concentration, leaf dry matter content, leaf mass per area, plant water availability, mean temperature of the warmest month, arid climate