Urbanization Intensifies Phosphorus (P) Limitation in Subtropical Forest Ecosystems----Chinese Academy of Sciences

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Urbanization Intensifies Phosphorus (P) Limitation in Subtropical Forest Ecosystems

Jul 19, 2019

Urbanization has been causing stress on natural environments, including nitrogen (N) deposition which negatively affect forest health. Although there is evidence that urbanization has changed forest N cycling, little is known about whether urbanization also changes the availability of phosphorus (P) which is important for plant growth and forest productivity.

Dr. HUANG Juan and the collaborators from the Research Group for Ecosystem Management, South China Botanical Garden of the Chinese Academy of Sciences carried out a survey in the Pearl River Delta region, the world's largest urban area in southern China, using two types of representative forests, the evergreen broadleaf forests (BFs) and pine plantations (PPs). This study was published in Science of The Total Environment.

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.