*2.1.2 Influence factors*

*Advances in Forest Management under Global Change*

tions [1].

**2. Challenges**

induced soil acidification [9].

**2.1 Nitrous oxide emissions**

*2.1.1 Nitrification and denitrification*

*Nitrification- and denitrification-related pathways [20–22].*

economic advantages. Development of *C. oleifera* industry would be beneficial for

As a typical economic tree, intensification such as water management, fertilization, and trimming takes an important part in the management of *C. oleifera* plantations. Notably, organic matter, available phosphorus, and pH value was low in *C. oleifera* plantation soils [7], constraining the yield of *C. oleifera* oil. Therefore, intensive management with fertilization is often performed in *C. oleifera* planta-

Fertilization is the major way of intensive management, efficiently improving the yield of oil in *C. oleifera* plantations. However, a large amount of nitrogen (N) input increased the risk of soil N leaching and gaseous N (e.g*.*, nitrous oxide (N2O), nitric oxide (NO), ammonia (NH3)) losing [8]. In addition, excessive N input

Nitrous oxide, as the major ozone-depleting substance [10], has been recognized

Soil systems contributed the largest source of N2O emissions (13 Tg N2O-N yr<sup>−</sup><sup>1</sup>

of which human activities accounted for 54% [13]. Nitrogen input such as N deposition and N fertilization often increased N2O emissions and altered the process of N transformation [14–17]. Generally, soil N2O emissions had a positive and linear relationship with N input [18]. About 120 Tg N was contributed by human activities per year [13]. Therefore, intensive N input often leads to high emissions of soil N2O [19].

Nitrification and denitrification are the two main pathways of N2O emissions

(**Figure 1**) [20–22], which produced global 70% soil N2O emissions [13].

),

to be an important greenhouse gas. Especially, the potential of N2O for global warming is 265 times than that of carbon dioxide [11]. The concentration of N2O is

ranging from 270 ppb in pre-industrial period to 329.9 ppb in 2017 [12].

the safety of edible oil and the conservation of soil and water in China.

**4**

**Figure 1.**

Soil N2O emissions can be influenced by soil environmental factors such as soil moisture, temperature, oxygen (O2), and pH condition [23, 24].

## *2.1.2.1 Soil moisture*

Soil moisture is a vital factor that affects soil N2O emissions. Generally, soil N2O emission rates reached the peak when soil water-filled pore space (WFPS) was 60–70% [25]. For example, soil N2O emissions were significantly higher under 60% WFPS conditions than that under flooded conditions [26].
