*4.3.5.4 Management of invasive plant species*

Invasive plants are capable of penetrating and replacing the existing indigenous vegetation of a location [65]. These are mostly exotic plants that have been introduced in a location, either intentionally or unintentionally, and that reproduce and spread on their own [66]. In the late 1970s and the early 1980s, the East African dry lands witnessed the introduction of various alien species. They include the 10 key invasive plant species that affect the drylands of Kenya and Tanzania [65], namely *Lantana camara* (Lantana), *Prosopis juliflora* (Mesquite), *Prosopis pallida* (Mesquite), *Opuntia ficus-indica* (Prickly pear cactus), *Caesalpinia decapetala* (Mauritius thorn), *Psidium guajava* (Guava), *Senna spectabilis* (Cassia), *Acacia farnesiana* (Sweet acacia), *Acacia mearnsii* (Black wattle), and *Acacia polyacantha* (White thorn).

Invasive plants are a hazard in the tropical dry forests and rangelands of East Africa, having increasingly created disasters that have affected the environment and socioeconomic well-being of communities inhabiting these dry regions. Some of the negative effects of invasive species include causing the death of livestock by poisoning and destroying livestock foliage, accelerating biodiversity loss via suppression of native plants, and increasing diseases by offering a breeding ground for mosquitoes and other insects that carry ailments such as nagana and sleeping sickness [65]. Of the 10 invasive species identified in East Africa, 90% suppressed native plant species and reduced biodiversity. Because invasive species could cause food insecurity and slow economic growth, their potential to derail attainment of the Country's Vision 2030 targets cannot be underestimated [67]. In addition, there is a need to explore and exploit the range of livelihood opportunities that invasive alien species, such as *P. juliflora*, present in drylands. In this regard, KEFRI and other partners have, for many years, conducted research and developed technologies for the control and management of this species through utilization.

### *4.3.5.5 Extension services and outreach*

Forestry extension is the art and science of converting information from research and past experiences to a practical level for use by local people who may not be specifically trained in forestry techniques [68]. There are two approaches to forestry

extension, namely top-down approach and bottom-up/participatory approach. The bottom-up approach is a two-way information flow system that considers prior consultation with target beneficiaries about their needs/problems and aspirations for effective planning. The top-down approach is a one-way information delivery system that reinforces the hierarchical relationship between the extension agent and the client [69]. The aim of forestry extension in the drylands is to help the pastoral people manage their livelihoods and their environment and to involve them in forestry development activities. Although forestry activities remain the main concern of the forestry sector, pastoralists look at their management activities in totality. For this reason, an integrated approach to extension involving relevant National and County Ministries usually strengthens extension services in the ASALs.

The drylands of Kenya are extensive, with low productivity and sparse populations, thus calling for appropriate forestry extension methods. The extension techniques appropriate for the ASALs and methods of developing them have been outlined [68, 69]. Some of the most commonly used extension methods include exploratory seminars, small meetings, public meetings, individual visits, and field exercises [70]. Efforts are made to establish the two-way flow of information from the forestry extension agents to the target groups in order to explore local problems and their solutions in the context of local traditions, knowledge, needs, and priorities. Common extension tools used include the media (radio, film, television, print manuals, and posters), field demonstrations complemented by video and audio tapes, slide shows, local actors, and direct discussions.

## **5. Conclusion**

This chapter provides an in-depth review of "desertification" as one of the most important challenges to livelihoods and development in the drylands of Kenya. The phenomenon results from climatic variations and human activities, such as destructions of water catchments and deforestation, that exert pressure on forests and woodlands leading to degradation, deforestation, and desertification. Desertification is, thus, a precursor to increased water scarcity. Overall, it causes reduced tree cover, reduces agricultural productivity, and increases water scarcity, climate change, destruction of water catchment areas and deforestation, which continue to increase water scarcity in Kenya. However, opportunities for remedial measures offer potential for intensified afforestation toward achieving the national target of 10% tree cover. More investment is needed for active and well-coordinated research toward rehabilitation and restoration of dryland resource systems. A significant impetus in combating desertification and drought is to devolve power to the people who are affected and to link environmental degradation to economic policies. Devolved action will attract local support to initiated programs. For sustainable development strategies to work, policies should put the welfare of the people in drylands at the center of the development agenda, uphold local people's rights, and empower the same people to adopt adaptive strategies to ascertain sustainable livelihoods. This review demonstrated the role of research and development in availing afforestation technologies in drylands to increase biodiversity and avert advancement of desertification in Kenya.

#### **Acknowledgements**

The authors acknowledge the support from the respective institutions of affiliations that allowed use of the data and information in their reports and granted us time to put together this write-up.

*Combating Desertification through Enhancement of Woody Floral Diversity in the Drylands… DOI: http://dx.doi.org/10.5772/intechopen.100399*
