As mentioned in Part 1 of All About Bamboo, bamboo has a lot of unique characteristics. In this part, we’ll discuss animal consumption of bamboo, and start the discussion on how bamboo is prepared and used for commercial purposes.
Bamboos are very important plants, both ecologically and economically. They are one of the most useful and valuable plants for people and provide the primary diet for giant pandas. Giant pandas are indigenous to mountain forests of small, cold-tolerant bamboos in the Yunnan province of southern China, and bamboo makes up 99% of their diet. Giant pandas eat the soft bamboo shoots, stems and leaves. Mountain Gorillas of Africa also feed on bamboo and have been documented consuming bamboo sap that was fermented and alcoholic. Chimps and elephants eat the stalks.
Bamboo timber is commercially harvested from cultivated and wild stands of bamboo. Some of the larger bamboos are the species in the genus Phyllostachys, also known as “timber bamboos.” When bamboo is used for construction purposes, it is critical to harvest the culms when they are at their greatest strength and when sugar levels in the sap are at their lowest.
Harvesting of bamboo should be undertaken according to the following cycles:
1) Life cycle of the clump: As each individual culm goes through a 5-7 year life cycle, culms should ideally be allowed to reach this level of maturity prior to full capacity harvesting. Well maintained clumps have a productivity level of up to 3-4 times that of an unharvested wild clump.
2) Life cycle of the culm: Bamboo should be harvested from 2–3 years through to 5–7 years, depending on the species.
3) Annual cycle: As all growth of new bamboo occurs during the wet season, disturbing the clump during this phase may damage the upcoming crop. Also during this high rain fall period, sap levels are at their highest. Picking prior to the wet season may damage new shoots, so it is best to harvest bamboo at the end of the dry season.
4) Daily cycle: During the height of the day, Photosynthesis is at its peak, which produces the highest levels of sugar in sap. Traditional practitioners believe that the best time to harvest bamboo is at dawn or dusk on a full moon.
To reduce the amount of sap in bamboo post-harvest the bamboo is either leached or post-harvest photosynthesis is used. Examples of this practice include:
- Cut bamboo is raised off the ground and leaned against the rest of the clump for 1–2 weeks until leaves turn yellow, allowing for the full consumption of sugars by the plant (photosynthesis).
- Cut bamboo is placed with the base of the culm standing in fresh water, either in a large drum or stream to leach out sap (leaching).
- Cut culms are immersed in a running stream and weighted down for 3–4 weeks (leaching).
- Water is pumped through the freshly cut culms forcing out the sap (this leaching method is often used in conjunction with the injection of some form of treatment).
After the water leaching process, the bamboo is dried slowly and evenly in the shade to avoid cracking in the outer skin of the bamboo. This reduces opportunities for pest infestation.
The durability of bamboo, in construction, is directly related to how well it is handled from the moment of planting through harvesting, transportation, storage, design, construction and maintenance. Bamboo harvested at the correct time of year, and then exposed to ground contact or rain, will break down just as quickly as incorrectly harvested material.
And while some use bamboo for food and construction, still others choose to use the vicose from bamboo for incredibly comfortable bamboo sheets and bamboo clothing!
Come back next week for Part 3 of All About Bamboo.
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