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Aerial Tree Seeding




AUG 2021


A Technical Report on Piloting Aerial Seeding in Maasai Mau Forest


Kiama, Stephen M.
Njuguna, Jane W.
Maua, James O.
Kaigongi, Magrate M.
Nadir, Stanley
John N., Kigomo
Koech, Charles K.
Michael M., Meso

Farmland Aviation Seedballs Kenya.jpg


Globally, land degradation and climate change are recognized as key factors that are increasingly driving the growing instability and fragility of human security. It is estimated that over 1.3 billion people are trapped on degraded agricultural land globally. In Kenya, forest degradation and deforestation is notably a serious problem, further worsened by the country’s low forest cover of approximately 7.4% of the total land area, which is lower than Africa's average of 9.3% and world average of 21.4%. Forest restoration is therefore a high priority agenda for the Government of Kenya. The Government is committed to various national, regional, and international land restoration initiatives, including: the Constitution of Kenya, 2010 which sets a minimum tree cover of 10%; Presidential directive to achieve and maintain over 10% tree cover by 2022; Kenya’s Vision 2030 which commits to protect the five (5) water towers and increase the forest cover to 10 %; and commitment to restore a total of 5.1 million ha of the country’s degraded landscapes by 2030 as contribution to the Bonn Challenge, New York Declaration on Forests, and the African Forest Landscape Restoration Initiative. Traditionally, forest restoration in Kenya has mainly employed the conventional method of raising tree seedlings and transplanting them in the field. The method is fit for restoration of small areas. However, using the conventional method to restore vast degraded landscapes such as those committed by the Government of Kenya, is not likely to deliver the desired results within the set timelines. Most degraded areas in Kenya are located in areas with inaccessible and difficult terrain. and their restoration using conventional method would imply huge costs and may therefore take many years. Aerial seeding is therefore appropriate for reforesting large areas that are disturbed and inaccessible due to difficult terrain. Aerial seeding is a technique for direct broadcasting of seeds by use of aerial means such as a drone, plane or a helicopter and therefore can be done quickly and at a relatively low cost. While the application of aerial seeding technology in rehabilitation of degraded forests is an old technique, it is relatively new in Kenya and localized protocols of its application in forestry are lacking. A pilot study on aerial seeding was therefore undertaken at Maasai Mau Forest (MMF) as a learning opportunity to develop aerial seeding protocols to guide its application in Kenya. The study was preceded by an evaluation that compared the costs of rehabilitation using five different technologies namely; manual seedling planting, aerial seeding using Winged Aircraft (Procured Services), aerial seeding using Helicopter (Procured services), aerial seeding using UAVs (Procured drone), and aerial seeding using Winged Aircraft (Government Owned Facility). The evaluation established that application of aerial seeding technology would cost Ksh 3,043 (about USD 30) per hectare, significantly lower than the cost associated with conventional method (manual planting of seedlings) estimated at Ksh 102,780 (or USD 1,028) per hectare. The country would therefore make a significant saving by using aerial seeding to address the restoration targets of 5.1 million ha. Based on the results of the evaluation, Ministry of Environment and Forestry (MoEF) recommended piloting of aerial seeding of 10,000 ha by 2022, distributed across four forest ecosystems, namely; Maasai Mau Forest (3,500 ha), Eburru Forest (500 ha), Aberdare Forest (2,500 ha) and Mt. Kenya Forest (3,500 ha). Maasai Mau Forest was selected as the first pilot site for aerial seeding. The pilot activity was planned and coordinated by a multi-disciplinary and multi-institutional technical implementation team drawn from the Kenya Forestry Research Institute (KEFRI) as the lead institution, Kenya Forest Service (KFS), Kenya Water Towers Agency (KWTA), Department of Resource Surveys and Remote Sensing (DRSRS), and Kenya Meteorological Department (KMD). Work of the team was guided by an action plan setting out key milestones and timelines. The Forest Area Reclamation Phase 2 in Maasai Mau Forest (locally referred as Sierra Leone / Kass FM areas) was delineated for piloting aerial seeding. The lands were mostly farmlands previously under occupation by peasant farmers and were highly degraded. The soil test results revealed that the soils were highly fertile and favorable for any kind of plant growth. A total of 107 sub-blocks (each measuring 100 ha) were defined and 35 sub-blocks earmarked for aerial seeding. Based on species-to-site matching, 35 tree species candidates for restoration were initially listed, ultimately narrowed down to 15 species based on their suitability for the selected site. Community meetings were also held and residents sensitized about aerial seeding in order to avert agitation from local communities which could raise security concerns. Aerial seeding services were provided by Farmland Aviation Ltd, seemingly the only firm with aerial seeding capability in the country at the time. Seeds were procured from Kenya Forestry Seed Centre and delivered to the airstrip a day before the exercise. Seeds were sorted into two categories: fluffy and non-fluffy seeds and for each category, seeds were mixed separately prior to loading into the aircraft’s hopper. The aerial seeding exercise lasted three (3) days, broadcasting 15 indigenous tree species weighing 3,580 kg and covering approximately 3,600 ha. While airborne, the aircraft automatically recorded SATLOCK data as evidence of the seeded area. In-situ seeding rate assessment showed that the quantity of seeds that landed on the ground from the aircraft during aerial seeding were approximately 8,400 seeds/ha. It was projected that over twenty eight million (28,000,000) seedlings would germinate over time, depending on physiological characteristics of respective species. However, some of the fluffy and light seeds such as those of Markhamia lutea and Hagenia abyssinica were blown off the target area and landed into the farms adjacent to aerial seeding areas. For purpose of post-seeding monitoring of the seed germination and survival of seedlings, four sub-blocks were ear-marked within the aerial seeded area. A parallel experiment of hand-broadcasting of tree seeds was also set in a 2-ha site adjacent to aerial seeded area. Seed of Seven tree species were hand-broadcast, cumulatively weighing 16.95 kg and were expected to achieve seeding rate of 10,000 seeds/ha combined. A number of technical lessons and recommendations can be drawn from the pilot aerial seeding exercise. Application of aerial seeding technology in restoration of degraded forestlands is significantly cheaper compared to manual planting of seedlings. Restoration using aerial seeding technology cost about Ksh. 3,043 (USD 30) per hectare in comparison to conventional seedlings planting which cost Ksh. 102,780 (USD 1028) per hectare. The technology is also faster and effective in rehabilitating inaccessible and difficult terrain. Community sensitization is evidently essential for building partnership and ownership of restoration of degraded forestlands. Very light seeds such as those of Markhamia lutea and Hagenia abyssinica are prone to being blown beyond the target area. Balling is therefore recommended to increase their weights to ensure they fall within the mapped area. However, seed balling presents an additional cost and challenges associated with increased bulkiness and weight. The desired seed density is mainly determined by calibration of the seed-release gate of the aircraft’s hopper and also by the species of choice. Higher seeding rates may be required for some tree species to enhance germination and establishment.

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