OPUNTIA STRICTA INVASION
Updated: Jun 16, 2021
The cactaceae is a large family with over 130 genera and 1922 species with the majority native from North, Central and South America. Numerous cactus species have been introduced around the world with different reasons, including ornamental plants and provision of fodder and edible products. Of these species, 57 have become naturalized and problematic globally, particularly in arid rangelands. Invasive cactus species have a negative impact on biodiversity and a range of economic activities. Opuntia stricta is a serious problem, mostly in arid and semiarid habitats .It grows forming dense mono-specific strands that completely disrupt habitats by displacing native species, reducing native biodiversity and modifying successional patterns. Opuntia stricta was first introduced to many regions for ornamental and hedging (live fencing) purposes but has grown to be a problem in Kenya, the invasive Opuntia stricta was first reported in the Laikipia plains of central Kenya and later reported in East Africa in Ethiopia, Uganda and Tanzania. The Opuntia stricta is also reported in Tsavo East National Park with an approximation of 500KM2 and is assumed to have spread to adjacent conservancies, this is mainly accustomed to the movement of animals like the elephants, which spread the seeds of the plant through their dung. The species has also been reported in small infestations along Lake Baringo growing amongst metamorphic and volcanic rocks, it is believed that it was first introduced to Laikipia North by a white colonel as hedging to his farm in 1950s, it then grew at an alarming invasion over the last 10 years. The endemic invasive plant has so far taken about 50-75% of the communal grazing lands of Mukogodo East and West, it occurs across the areas along rivers, homesteads and mountains taking up the valuable grazing land. The plant has also spread to other areas and is mainly spread by baboons, elephants and human defecation, it has led to land degradation, poor livestock health such as blinding of the eyes due to its fine spines that get stuck in the eyes of the animals, glochids within the intestines which results to loss of weight and milk production and eventually death of the animals.
A recent study shows that pastoralism is no longer a viable livelihood because of land appropriation, increased limited opportunities for livestock mobility, growing livestock densities and over grazing, and growth of the human population. This suggests that, the increased invasion of species like Opuntia is a contributing factor. In 2012, a 16ha fence was erected around the Twala Women's Group Cultural Manyatta to keep away all wild and domestic animals, opuntia stricta was present in the parcel at the time. By the end of 2013, there was a considerable grassland and tree regeneration which was choking Opuntia stricta, this suggests that restoration of natural herb layer and tree cover might stop the spread of Opuntia stricta by reversing the degradation that facilitated its expansion in the ﬁrst place.
And as mitigating efforts, earlier attempts have been made to eradicate and utilize the plant, efforts in production of organic cactus-based products such as biogas production by a certain individual, juice, honey red wine and jam used in bread by Twala women group and Laikipia permaculture, are the edible by products of the plant in efforts to utilize and eradicate the plant. However, the plant can be controlled physically by removing smaller infestation manually through digging, cutting down the plant, burning it, and even burying it. But its mode of dispersal and rate of growth have proved to be a challenge in handling the alien plant.
It lies at the meeting point of the Somali Maasai bushlands and Afromontane-Afroalpine biotic zones represented by grasslands, shrubby bushland and dry forest. The community is mainly Maasai who are purely livestock keepers, mainly goats, sheep and cows with land being communal. The soil type is mainly sandy. Wild animals roam freely in the area, more so the elephants and the baboons increasing tourism economy to the surrounding privately owned conservancies. The elephants and baboons are the main carriers of the Opuntia stricta seeds through their excretion hence the spread as well as human beings through their defecations.
The Indigenous peoples and local communities within Laikipia north, Mukogodo East and West Wards are people with high mobility due to their means of livelihood that are largely dependent on rearing livestock. They use their indigenous traditional knowledge in many practices of solving many challenges within their territory. However, the communities are facing many challenges in maintaining their livelihood due to the hard-hitting effects of opuntia stricta. Opuntia stricta has gradually `killed` other cactus species such as the Opuntia fico Indica whose fruits were sweet and edible. It has adversely affected the environment by invading other plant species like the acacia shrubs. Its fast growth rate has enabled it to occupy most parts of the environment making it hard to mitigate despite efforts in place. Its endemic effects to the livestock production is increasing vulnerability among the people hence their losses in economic gains as they solely depend on these livestock. Elephants and baboons readily consume the fruits of the Opuntia stricta and defecate elsewhere which enables its spread. It is therefore in order to say that the invasive plant is a real dangerous hazard and disaster within the area.