The results showed that leaf N:P ratios in the two forest types were high (20–50) with a significant increasing pattern along the rural-to-urban gradient, suggesting that P limitation was intensified along urbanization.
Besides, they observed the negative effects of urbanization on soil microorganisms on the basis of the decreased abundance in actinomycetes and gram-negative bacteria along the rural-to-urban gradient.
There were divergent key factors for P limitation respond to the urbanization in the two forest types. In BFs, broadleaf trees showed a greater response to N deposition from urbanization indicating direct leaf N uptake from N deposition is a key factor. Alternatively, in PPs, soil acidification is an important factor accelerating P limitation.
This study revealed that urbanization intensifies plant P limitation in subtropical forests and the effects vary depending on forest types, which provide empirical information to support the management of forest ecosystems and evaluation of urbanization effects on forest health.
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