This archive report was first published on 5 June 2020.
Published on June 5, 2020, by TIM WANYONYI
Pinus patula, also known as Patula pine or Mexican weeping pine, is a native Mexican species that has naturalized in many parts of the world, including Africa, Australia, Brazil, New Zealand, Argentina, and Southeast Asia.
Its introduction to Africa dates back to 1907 in South Africa, and it has since spread to the rest of the continent.
In Kenya, Pinus patula is the most important pine species, valued not only for its premium timber products but also for its ability to remove carbon from the atmosphere.
The tree has several local names, including msindano (Kiswahili), mucinda-nugu (Kikuyu), and omobunduki (Kisii).
According to the Kenya Forest Research Institute's (Kefri) Guide to Tree Planting in Kenya, Pinus patula grows in ecological zones between 1,600 to 3,000 metres above sea level and is moderately drought-tolerant, with an average annual rainfall of 750mm to 2,000mm in its native habitat.
However, in Kenya, it grows in zones with annual rainfall ranging from 800mm to 1,400mm.
Like the blue gum, Pinus patula is fast-growing and uses a lot of water, making it suitable for soil stabilization due to its fibrous roots but not ideal for planting near water sources or with crops.
Its fast growth makes it useful in climate change control, and like its whistling pine cousin, Pinus patula produces excellent fuel wood that burns even when green and wet.
The tree's fibre is used in the commercial manufacture of pulp in the paper industry and boards.
Pinus patula grows up to 30 metres tall and can be harvested for pulp at between 16 and 20 years and for timber at 20-30 years.
Its timber is soft and rated at a higher premium than that from the whistling pine, selling at an average of Sh55 a foot, the same price as cypress.
When tapped, Pinus patula yields oleoresin, which is distilled to give turpentine, and rosin, used in paint and batik industries.
The tree is one of the most important in carbon sequestration, a crucial service for regulation and mitigation of climate change through reduction of greenhouse gas emissions.
A study by the Forestry Research Network of Sub-Saharan Africa found that Pinus patula removes high amounts of carbon from the atmosphere.
The study involved 99 plots measuring 20 by 50 metres in government-managed forest plantations of selected species, with significant differences in carbon sequestration among species across sites.
However, eucalyptus saligna had the highest amount of carbon sequestered in Nyeri South, followed by Pinus patula in Nyeri North and Cupressus lusitanica in Kiambu.
The study concluded that carbon sequestered from selected tree species in central Kenya demonstrated a significant contribution towards reduction of harmful gases, specifically carbon dioxide, which is among greenhouse gases that trap heat in the atmosphere and drive climate change, causing floods, droughts, and wildfires.
CarbonBrief estimates that emissions will drop by 5 per cent this year due to the economic impact of the coronavirus disease (Covid-19), while the United Nations says the world needs a drop of 7.6 per cent annually until 2030.
Pinus patula is propagated through seeds, which go for up to Sh7,000 a kilogramme at Kefri shops.
Pre-sowing treatment is not necessary, but germination may be boosted by soaking in cold water for at least 24 hours.
The germination rate can be low, and to test the viability of the seeds, put them in a container filled with water and separate those that sink from those that float.
The seeds that float are generally the ones that are least likely to germinate.
The bed should be covered with mulch and kept moist, with the seeds taking between seven to 14 days to germinate.
Transplant when a foot tall, and the ideal spacing while planting is three metres.
