With the recent flooding throughout the Americas these last few months, I thought to address a little known, but extremely important, forgotten grass: bamboo.
Bamboo is an arborescent (treelike) grass belonging to the family Poaceae, subfamily Bambusoideae. The family Poaceae, true grasses, is thought to comprise 20% of the known vegetation covering the Earth.[1] Grasses are extremely important to both the ecology at large, as well as to humans specifically. Grasses provide us with a host of benefits, three of which are supplying staple food crops, conserving soil moisture, and preventing soil erosion.
Like common lawn grasses, bamboo spreads by roots called rhizomes and must be removed by digging up the roots themselves. An entire grove of bamboo is usually just one plant, for the roots are all connected and grow from the mother clump. Bamboo is classified as either a clumping bamboo or a running bamboo.
Clumping varieties grow slowly and spread through very short rhizomes that keep the bamboo stocks close to the mother clump. These varieties are easy to contain and rarely get out of hand before the property owner notices. Running varieties grow more rapidly and spread far and wide, growing very long rhizomes that can be unmanageable when left unattended for years on end. Clumping and running bamboos can be herbaceous (foliage stocked) and deciduous (woody stocked), as well as tropical and temperate.
Unlike common lawn grasses, woody stocked bamboo is stronger than hardwood and softwood timbers in both tension and compression. The tensile strength of the fibers of a vascular bundle of a giant bamboo can be up to 12 kilograms per square centimeter, almost twice that of steel.[2] Even the rhizomes are much thicker and stronger than typical lawn grasses, needing an ax for separation, harvesting, and removal.
Bamboo roots only grow between 6 and 20 inches into the topsoil and can comprise several thousand meters in length in a very small, densely packed area. In a Japanese study conducted in 1960 on several groves of two Japanese varieties, the total length of living rhizomes per one-tenth hectare (two-tenths of an acre) was between 6,300 to 18,740 meters for Phyllostachis reticulate, and 47,000 to 57,920 meters for Pleioblastus pubescens.[3]
This root density gives bamboo a trait unlike any other plant: it prevents soil erosion to such a degree as to stop landslides. This is extremely important for river banks with frequent flooding and for areas prone to earthquakes. It is commonly known throughout Asia and Latin America that the safest refuge during an earthquake is in an established bamboo grove, which is usually considered any stand that is over ten years old.
I’ve been growing bamboo for seven years now and have acquired a wide range of varieties. The oldest of my stands was established from a mother clump of just three stocks and a root ball less than one square foot. Seven years later this grove of Yellow Groove Bamboo (Phyllostachys aureosulcata) is 28 feet long, 7 feet wide, and this year’s growth has topped 50 feet in height. When it reaches full maturity, it will be difficult for rabbits to penetrate.
Temperate varieties, those which I grow, only send up new stocks from early April till late May. The rest of the year its roots absorb nutrients for the next season’s growth. As the roots expand, the number of stocks produced increase exponentially. The average growth rate for our temperate varieties is two new stocks for every one existing stock for the first five years, and then begins to expand from the exterior layer only.
For example, 1 stock produces 2 new stocks the first season; these 3 stocks produce 6 new stocks the second season; these 9 stocks produce 18 stocks the third season; the 27 stocks producing 54 stocks the fourth season; with 81 stocks producing 162 stocks by the fifth season. This growth rate then continues only from the exterior layer of bamboo, reaching over 500 stocks by the tenth year.
More than just preventing soil erosion and landslides, bamboo attributes are immense. Depending on the specific variety, bamboo is an excellent building material; offers edible rhizomes and leaves; provides wind breaks, sound barriers, privacy fences, and bird sanctuaries; can be manufactured into a host of consumer products, such as plastics and textiles; desalinates (removes salt) and purifies contaminated soils; remains leafy and green year-round; and is the only living thing known to withstand the nuclear radiation of an atomic bomb.
On August 6th, 1945, Hiroshima, Japan was hit by the atomic bomb that produced incinerating heat, a concussive shock wave, and a towering cloud that cast day into darkness. Within a matter of seconds, one half of the city’s population perished and 70,000 buildings were destroyed. Wood houses ignited, steel twisted, and stone glowed. However, in the very epicenter, a thicket of bamboo stood through the blast suffering only scorching on one side. A portion of the thicket remains alive today at the Memorial Museum for Peace in Hiroshima, Japan.[4]
Bamboo is truly amazing!
[1] http://en.wikipedia.org/wiki/Poaceae
[2] Bamboo: The Gift of The Gods by Oscar Hidalgo Lopez, 2003, page III
[3] Bamboo: The Gift of The Gods by Oscar Hidalgo Lopez, 2003, page 6
[4] Bamboo: The Gift of The Gods by Oscar Hidalgo Lopez, 2003, page 75