Pests and diseases affect the early natural regeneration of the oak (Quercus aliena var. acuteserrata) population

Insects and pathogens interact with plant species, influencing the natural
regeneration of plant populations. However, the mechanisms by which they
mediate the early regeneration process remain unclear. Herein, we
evaluated the pest and disease status of 380 Quercus aliena var.
acuteserrata seedlings and its effects on their photosynthetic and
physiological properties in the Qinling Mountains, China. Results
indicated that 243 seedlings were affected by pests and diseases, mainly
in the 0−20 cm height range, and the affected leaf area was mainly in the
range of 0−60%. Biology and soil factors were the primary drivers of these
conditions, with canopy density being a largely influencing factor.
Disease significantly decreased the chlorophyll content (Chl),
net-photosynthesis (Pn), stomatal conductance (Gs), intercellular CO2
concentration (Ci), and transpiration rate (Tr) in seedlings but increased
malondialdehyde (MDA) and soluble sugar content. The light-response curve
varied among pests, diseases, and healthy seedlings. Pest stress prompted
the seedlings to maintain high levels of photosynthesis unlike the effects
seen with diseases. Our findings highlight the impact of biotic factors on
forest natural regeneration and contribute to enhancing healthy forest
management and promoting sustainable development.