Abstract:

Larix principis-rupprechtii and Picea meyeri mixed forest is a typical mountain forest in northern China. Understanding the functional traits of the regenerated seedlings and saplings of these two species is a key to know the current understory regeneration pattern. Light environment (two light regimes, gap and understory with 100% and 40%-60% transmittance levels) was selected as the main factor and plant age (two level, 3-4 and 6-8 years old) as sub-factor. The gas exchange parameters, specific leaf area (SLA) and stem dry mass of the two species were measured to investigate the inter-specific variation at different ages in response to light. The results showed that there were significant differences in the gas exchange parameters, SLA and stem dry mass between Larix principis-rupprechtii and Picea meyeri. Picea meyeri showed a conservative resource use strategy in water relations and morphological traits, but a high carbon assimilation strategy in photosynthetic capacity. As light intensity decreased, the gas exchange parameters of Larix principis-rupprechtii increased and Picea meyeri had a negative response in stem dry mass. Meanwhile, as the tree age increased, Larix principis-rupprechtii did not respond to light in measured traits, while the stem dry mass and SLA of Picea meyeri decreased with light intensity, which showed a different response pattern from Larix principis-rupprechtii. Because of the concurrent effects of other understory factors, e.g., water availability, soil nutrients and competitions, the results should be further confirmed in future studies.

Key words: Larix principis-rupprechtii, Picea meyeri, light environment, development stage, gas exchange parameters, response, functional traits