**5. Forest plant invasions and soil N cycling**

N is a key factor determining the outcome of interspecific competition in many ecosystems [55–57]. Previous literature found invasive plants dominant over the native plants because of they have more nutrient utilization, high photosynthetic rate, increased biomass production, more N availability from litter, high decomposition rate [58]. In addition invasive species produce fast-decaying litter [48]. Such characteristics of plant invasions can accelerate/increase soil N cycling by altering soil microbial community which further affects N2O emission and forest ecosystem services in the invaded site [59, 60]. It may vary the types of plant invasion, such as woody plant invasion and N-fixing plants which have more significant impacts on N cycling than their alternatives. There is no difference between the responses of forests, wetlands, and grasslands to plant invasions [49].

**47**

*Plant Invasion and N2O Emission in Forest Ecosystems DOI: http://dx.doi.org/10.5772/intechopen.92239*

position rate, which can affect the soil N cycle.

N is a key nutrient, limiting factor for biomass production in forest ecosystems [57, 61]. No plant is suitable for all habitat to grow potentially [47, 62, 63]. However, invasive plants efficiently utilize resources showing maximization in growth, competition, and reproduction and improving their invasiveness characteristics [57, 62, 64, 65]. The N use efficiency of invasive plants is enhanced by many ways such as N fixation, photosynthetic N use efficiency, and N mineralization, allowing invasive

Rapid nutrient cycles especially N cycle may promote the invasiveness of plants [49, 59, 67, 68]. Also, increased N availability may affect the activity of soil microbial community with invasive plants and contribute to further invasion and provide a favorable environment for soil microbes [46, 59, 69]. Plant invasion changed (a) soil microbial community, (b) physiochemical properties, and (c) litter decom-

a.Plant invasion helps in the succession of soil microbes and promotes their functions, further facilitating plant invasions [70–72]. Some finding suggests that invasive plants in the invaded site may cause positive structural change in microbial community, which results in negative effects on native plant community, establishment, growth, and the whole ecosystem [56, 73]. Increasing the availability of N by invasive plants through changed in soil microorganism structure and community in result rapid decomposition, or through N2 symbiotic fixation can further accelerate the N cycles [49, 58, 59, 74, 75]. These changes of plant invasion and especially the symbiotic N fixers have large effects on N cycles [58].

b.There is considerable evidence that plant invasion may alter physiochemical properties of soil. For example, invasive plants may cause soil moisture reduction with rapid evapotranspiration because of the long survival and rapid growth of invasive plants [75–77]. Some studies also observed a positive association between plant invasion and soil moisture [78]. Invasion of plants results in high pH value in soil, such as more ammonium and nitrate absorption result in acidification and alkalinization [78–80]. Si et al. [81] findings show that lowdegree plant invasion increased soil pH value, but high-degree plant invasion did not. A decrease in soil pH values caused by invasive plants could improve the solubility of P in soil, which contributes to further plant invasion [82]. Such factors, soil pH, soil moisture, and temperature are regulating soil microbes, soil N availability, litter decomposition rate, and community structure, thus also affecting the physiochemical properties effects on plant invasions [83, 84].

c.Fast-decaying litter of invasive species increases soil nutrients, especially N [83]. Thus, invasive plants obtain more nutrients especially N, and fast decomposition might also impact N cycle and further promote plant invasions [83, 85, 86]. Leaf litter quality and remarkable condition in the surrounding environment created by plants such as an increase in soil temperature and moisture can affect litter decomposition rate [87]. Invasive plants are often found with higher leaf N

Soil N availability and transformation (mineralization, nitrification and denitrification) process from unusable form to usable form for plants is a key factor for primary net production. The involved microbes in nitrification and denitrification process are associated with N2O emission [12, 88]. More N2O emissions from the forest soil further accelerate global warming, thus greatly affecting N inputs to the soil by litter production through rapid decomposition by invasive plants [37, 51].

concentration affecting litter decomposition rates [51].

species to have an advantage over native plant population [47, 56, 57, 66].

#### *Plant Invasion and N2O Emission in Forest Ecosystems DOI: http://dx.doi.org/10.5772/intechopen.92239*

*Advances in Forest Management under Global Change*

Forest management includes prevention of arrival and dispersal of invasive species and their biological control as well as silviculture and restoration practices to lessen invasion impacts [45]. Restoration should be based on choosing plant species which suit to the condition of the target area [53]. For example, to increase the forests canopy cover may resist those invading species which demanding for more light, thus, invasive species with high resource demanding can be managed by proper way to minimize its further effects [54]. Also, a better understanding of the mechanism, affecting factors, impacts, and control of the invasive species will lead to a proper forest management. The (**Figure 1**) model is based on invasive species management,

*A stepwise model is leading an effective forest management of invasive species (adapted from [53]).*

N is a key factor determining the outcome of interspecific competition in many ecosystems [55–57]. Previous literature found invasive plants dominant over the native plants because of they have more nutrient utilization, high photosynthetic rate, increased biomass production, more N availability from litter, high decomposition rate [58]. In addition invasive species produce fast-decaying litter [48]. Such characteristics of plant invasions can accelerate/increase soil N cycling by altering soil microbial community which further affects N2O emission and forest ecosystem services in the invaded site [59, 60]. It may vary the types of plant invasion, such as woody plant invasion and N-fixing plants which have more significant impacts on N cycling than their alternatives. There is no difference between the responses of

a stepwise model leading an effective management of species.

forests, wetlands, and grasslands to plant invasions [49].

**5. Forest plant invasions and soil N cycling**

**46**

**Figure 1.**

N is a key nutrient, limiting factor for biomass production in forest ecosystems [57, 61]. No plant is suitable for all habitat to grow potentially [47, 62, 63]. However, invasive plants efficiently utilize resources showing maximization in growth, competition, and reproduction and improving their invasiveness characteristics [57, 62, 64, 65]. The N use efficiency of invasive plants is enhanced by many ways such as N fixation, photosynthetic N use efficiency, and N mineralization, allowing invasive species to have an advantage over native plant population [47, 56, 57, 66].

Rapid nutrient cycles especially N cycle may promote the invasiveness of plants [49, 59, 67, 68]. Also, increased N availability may affect the activity of soil microbial community with invasive plants and contribute to further invasion and provide a favorable environment for soil microbes [46, 59, 69]. Plant invasion changed (a) soil microbial community, (b) physiochemical properties, and (c) litter decomposition rate, which can affect the soil N cycle.


Soil N availability and transformation (mineralization, nitrification and denitrification) process from unusable form to usable form for plants is a key factor for primary net production. The involved microbes in nitrification and denitrification process are associated with N2O emission [12, 88]. More N2O emissions from the forest soil further accelerate global warming, thus greatly affecting N inputs to the soil by litter production through rapid decomposition by invasive plants [37, 51].

**Figure 2.**

*The dynamic feedback diagram between invasive plants, soil properties, and soil N cycles (modified from [89]).*

Invasive plants are often found with high soil N content because of the fast-decaying litter production [48], which may affect the activity of soil microbial community, providing favorable environment to them [59, 69], such as increase in soil temperature [87], which may not be the same case for native species (**Figure 2**).
