Physiological and growth variations of Quercus mongolica saplings along an elevational gradient in Changbai Mountain Nature Reserve, northeastern China

Objective This paper aims to reveal the inner mechanisms of vegetation growth to elevational gradient and provide scientific basis for predicting the impact of climate change on vegetation growth of Quercus mongolica in Changbai Mountain Nature Reserve, northeastern China.

Method We used the Quercus mongolica saplings under the canopy to evaluate leaf physiological characteristics, leaf morphological characteristics and plant growth characteristics of Quercus mongolica at different elevations.

Result The results were as follows: (1) there were no significant differences (P > 0.05) between the average needle leaf mass per area (LMA) and leaf dry mass content (LDMC) from various elevations. The apparent quantum yield, the saturation light intensity, the light saturated net photosynthesis, the water use efficiency and apparent CO₂ use efficiency were negatively correlated with elevation, i.e. the ability to utilize low light, the ability to adapt to strong light and the maximum photosynthetic potential decreased with elevation, while the consumption of water and intercellular CO₂ required for the production of organic matter increased with elevation. (2) Leaf biomass, new branch biomass, one year old branch biomass, leaf biomass proportion, new branch biomass proportion and one year old branch biomass proportion were also negatively correlated with elevation, i.e. the annual growth of Quercus mongolica saplings decresed with elevation. (3) All leaf factors in this study explained 12.03% of total growth variation, while all environmental factors in this study explained 19.31% of total growth variation of Quercus mongolica saplings.

Conclusion The elevational responses of leaf physiological characters and whole plant growth characters of Quercus mongolica reflect that this species has strong plasticity in heterogeneous habitats. There is no significant difference in leaf mass per area and leaf dry mass content of Quercus mongolica from different elevations, but the photosynthetic rate and annual growth decrease with elevation, namely environmental variations may affect the growth of saplings by affecting the photosynthetic characteristics rather than the morphological characteristics of the leaves, in turn, affect the growth of Quercus mongolica saplings. This paper is of certain significance to predict the physiological and ecological response of Quercus mongolica under the future climate change.