**15. Understandings for the management of** *P. juliflora*

A study by Shanwad et al. [106] indicates that control of *P. juliflora* is extremely difficult and costly for eradication once it invaded ecosystems. Report by Pasiecznik et al. [43] also confirmed that once *P. juliflora* established into large areas, prevention of further spread is not possible as the species quickly builds up soil seed bank. Thus, it required regular removal of all new seedlings over very many years, as seeds could remain viable for more than 40 years [31]. To control its invasions, different strategies can be applied such as eradication by utilization and mechanical control of *P. juliflora*. The potential irreversibility of the damage of invasion costs and may impose countries economic losses for management. The main management reactions after an alien species invaded are mitigation and adaptation [91].

To reverse the situations, integrated management strategies, participation of all stockholders and multidisciplinary research approaches within and across countries should be designed. To control invasive alien plants, various management options are tried but barriers faced for management in developing counties like Ethiopia [2]. In the invaded areas, experiences indicate that there are several methods of *P. juliflora* management. Chemical, mechanical, biological, management by utilization, and disrupting phenology of *P. juliflora* are among the management methods to control the species. There are three methods for the control of *P. juliflora* namely mechanical, chemical, and biological strategies [30]. Control of *P. juliflora* by utilization is an effective control way and management. In the following subsections, the pros and cons of management and control of *P. juliflora* invasions are discussed.

#### **15.1 Chemical control methods for** *P. juliflora*

Several available herbicides were tried to control *P. juliflora*. For example, the study by Shanwad et al. [106] shows combinations of chemicals reduced growth and development of *P. juliflora.* In their study*,* Mera-71, 2, 4-D ester followed by paraquat was the best in affecting weed recovery. The control of the regrowth of *P. juliflora* was effectively achieved by two times applications of systemic trans-located herbicides like Mera-71 (Glyphosate) and 2, 4- compared to paraquat, diuron. Controlling *P. juliflora* through chemicals at juvenile stages is highly effective than adult stages. Eradication of *P. juliflora* has been attempted in several countries through chemicals but has proved unsuccessful and chemical eradication is not environmentally friendly [107]. In, Ethiopia this management strategy was also tried to control *P. juliflora* but failed to manage it.

#### **15.2 Mechanical control methods of** *P. juliflora*

The mechanical control of *P. juliflora* is very labor-intensive, expensive, and economically feasible only for high-value lands. Mechanical control method of *P. juliflora* plant was recommended to cut at 10 cm for young trees and 40 cm for matured stems to control coppicing (**Figure 6**). Control of the spread of the *P. juliflora* is ineffective to eradicate it by mobilizing communities. Management of *P. juliflora* by utilization such as fuel wood, construction, and charcoal production, feed livestock by crushing pods are the best management options [57, 93]. But small-scale households cannot afford to control using mechanical methods. Pastoralists, agro-pastoralists, and urban dwellers should also manage their territory of rangelands, woodlands, homesteads, and compounds through hand weeding of *P. juliflora* seedlings. This method can minimize its invasion before it takes roots in different land uses. However, some of these methods need labor costs for control. Since cutting promotes regeneration, all mechanical methods of control cannot be recommended [107]. This management strangely was largely applied in Ethiopia to control the invasion of *P. juliflora* in Afar and Somale region, but did not succeed.

#### **Figure 6.**

*Phenological patterns of* P. juliflora *in the Awash Fentale and Amibara Woredas, Afar region of Ethiopia in 2016/2017 cropping season. (Source: Shiferaw et al. [83]).*

*Effects of the Invasive Alien* Prosopis juliflora *(Sw.) DC and Its Management Options… DOI: http://dx.doi.org/10.5772/intechopen.108947*

According to Shiferaw et al. [83], disrupting the phenology of *Prosopis juliflora* or aborting the juveniles of the species throughout the year, particularly during the peak time of flowering before seed set could also be used for the management *P. juliflora*. This method controls the species before it disperses seeds into the soil stores as a soil seed bank (**Figure 6**). These needs forced community involvement during its flowering times like yearly voluntary and community participation in soil and water conservation works in Ethiopia. During floral removal, care should be taken due to the allergy to its pollination.

According to Pantaik et al. [10], pollens of *P. juliflora* trigger allergic asthma, rhinitis, and skin allergy. Defoliation of only the leaves of *P. juliflora* also inhibits photosynthesis of the species (**Figure 6**). But, this method of destruction of leaf parts needs care not to cut the branches as *P. juliflora* aggressively propagates by all parts of its stems. Appropriate silvicultural techniques (e.g., thinning) of *P. juliflora* should also be practiced to lessen the invasiveness and effects on other plants [55]. For instance, a research by Singh et al. [108] shows that plant height was recorded to be 20 and14% higher in *P. juliflora* and *A. nilotica* respectively grown in combination with grasses than the sole plantation of these species applying a silvicultural treatment of *P. juliflora*. Moreover, Walter and Armstrong [109] reported that proper silvicultural management increased the quality of wood for maintaining its benefits for livelihood and control the invasion of *P. juliflora*. This management strategy could not be tried in Ethiopia at large to control the progress of *P. juliflora* into various vegetation ecosystems to enhance the values we get from ecosystem services.

#### **15.3 Biological control methods of** *P. juliflora*

In recent decades, biotic control has increased recognition in various countries due to lucrative and reliable means of managing large invasiveness of alien plants. It comprises the restrained, strictly administered introduction of one or more species of highly studied alien organisms that blizzard from the original home ranges of invading plant species, and which physiologically are reformed to feeding absolutely on or attacking completely plants of that [30]. In Africa, though the goal of cooperation for biological control of *P. juliflora* in South Africa with other countries, it delayed trendy due to the controversy for the introduction of biological control agents onto *P. juliflora*. Additionally, debates about the relative value and costs of trees continued to hinder progress with the planned increase of biological control [110]. Ravhuhali et al. [111] concluded that managing the spread of invasive species could also be accomplished using livestock as biological control while improving the productivity of the animals (e.g., *P. juliflora* pods utilized for livestock feed ingredients with other feeds). The release of bio-control agents was also considered where these technologies were not feasible because careless release in some species might escape and change into invasiveness inclining to threaten the native organisms [107]. These strategies were not largely tried on research fields of Ethiopian Agricultural Research Institutes, for instance, and had no theories in management of *P. juliflora* in the invaded areas of Ethiopia.

#### **16. Conclusions**

*P. juliflora* has effects on the soil environment in the form of allelochemicals that are ingredients in its plant parts that have effects on living organisms, take over land uses land cover aggressively, economic loss, the health of humans and animals, and reduce the diversity of organisms. On the other hand, the species is used to ameliorate soil properties (soil physical, biological properties), e.g., sequester CO2 for mitigation of greenhouse effects, and other economic values (construction materials, furniture, medicinal values, sources of pollination for honey production, and animal feeds, etc.) particularly in the semiarid and arid tropics. However, the negative effects of *P. juliflora* exceed its positive values. Mechanical, chemical, management by utilization, fire regime, disrupting its phenological stages, and biological control methods have their pros and cons to control *P. juliflora*. Therefore, prevention, integrated management strategies, and management of the species by utilization are the best measures used to control *P. juliflora* recommended globally and in Ethiopia. Mechanical methods (aborting phenological stage, utilization of the species, others) need awareness of the communities, and forced mobilization is vital for effective and efficient management of the species.

Previously, in several countries, the management methods, namely mechanical, chemical, and biological, were being tried to control the alien *P. juliflora*. But all the methods failed to eradicate the species. As a result, the species is continuing to invade and take valuable farmlands, grazing lands, rural homesteads, wetlands, roadsides, and urban areas, particularly in Afar and Somali regions. In Ethiopia, more research involving multidisciplinary research approaches should be designed to conduct the effects of *P. juliflora* on the environment, economy, and health of animals and communities. Moreover, other teams should also design other effective and efficient management designs that are different from previous researches that is vital to alleviate the invasion of the species and thus improve the livelihood of inhabitants in the region.
