Increasing atmospheric nitrogen (N) deposition and changing precipitation regimes could profoundly impact community structure and ecosystem function in forests. Our current knowledge of N deposition impacts on forest ecosystems largely derives from numerous field manipulative experiments. However, almost all the previous experiments mimicking N deposition have been conducted by adding N solution and/or fertilizer directly onto the understory plants and/or forest floors. These conventional experiments with understory N and water addition largely neglect canopy-associated biota and processes and therefore may not realistically simulate atmospheric N deposition and increased precipitation to generate reliable impacts on forest ecosystems. In addition, it is unclear whether N addition and water increase interact with each other to affect community structure and ecosystem functions in forest.
The N and water manipulative experiments is conducted in Jigongshan National Nature Reserve (31°48′ N, 114°02′E) in Central China, within a transitional zone from subtropical climate to warm temperate climate region. Four blocks were established in deciduous forest, and each treatment was replicated once within each of the four blocks. In each block, seven circular plots (semi-diameter = 17 m) were assigned to the following 7 treatments: control, canopy N addition with 25 kgN ha-1yr-1, canopy N addition with 50 kgN ha-1yr-1, understory N addition with 25 kgN ha-1yr-1, understory N addition with 50 kgN ha-1yr-1, canopy water addition by 30%, canopy N addition with 50 kgN ha-1yr-1+ canopy water addition by 30%. All treatments were conducted from April to November each year.
Yanchun Liu, Mengjun Hu, Yongheng Song, Shiqiang Wan
Wei Zhang, Weijun Shen, Shidan Zhu, et al. CAN Canopy Addition of Nitrogen Better Illustrate the Effect of Atmospheric Nitrogen Deposition on Forest Ecosystem? Scientific Reports, 2015, 5, 11245.