BAMBOO RESOURCES OF MIZORAM
Bamboo forests cover a large extent of area in Mizoram. The State possesses the maximum percentage of its geographical area under bamboo forests as compared to other States of the country. Bamboo forests are most abundant in the five northern districts but are rare in the eastern and south eastern parts of the State, particularly in Champhai, due to high altitude. Most of the bamboo species occurring in the State are found between 400m to 1,500m altitude and their distribution is somewhat restricted to above 1,550m. However, Sinarundinaria falcata, S. griffithiana and Schizostachyum fuchsianum occur in the high elevations of Blue Mountain and Mt. Chalfilh, which are above 1,500m altitude. Bamboo also grows as under-storey plants in tropical evergreen and moist deciduous forests, in pure stands along river banks, in and around villages and as dominant secondary vegetation on abandoned jhum lands. Clear felling in primary forests for jhum cultivation results in establishment of bamboo specially 'muli' which dominates the species composition.
The Forest Survey of India made an assessment of the bamboo resources of the State in 1988-89 and estimated the total growing stock to the tune of 16.54 million tonnes with an annual yield of 3.23 million tonnes. The domestic consumption during 1988-89 was estimated as 28,315 tonnes, thus leaving a surplus of 3.209 million tonnes. Another survey of the bamboo area was conducted by the Eastern Zone, FSI, Kolkata during 1991-92. It covered 20 mahals in seven forest divisions viz., Aizawl, Champhai, Darlawn, Kawrthaw, Kolasib, Mamit and Tlabung covering an area of 1,772 2km , and according to their results, the non-clump forming bamboos accounted for 98% of the total growing stock with 725.68 million culms (over one year old) having a total weight of 1.77 million tonnes. Later, Rai and Chauhan (1998) estimated the total growing stock of bamboos at 10.89 million tonnes (green weight)and 6.53 million tonnes on dry weight basis. The total number of culms was reported to be 6,130.43 million spread over a bamboo area of 9,210.3 km .Recently the bamboo resources of the State have been assessed by the Mizoram Remote Sensing Application Centre (MIRSAC) in 2008 with the help of satellite imageries and ground survey through a project sponsored by the State Environment and Forest Department. MIRSAC adopted the selective systematic sampling method for selecting the sample locations in different districts/ forest divisions of the State. A total of 7,200 sampling units covering an area of 72 ha were enumerated for counting of culms and prediction of growing stock. For enumeration purpose, a culm is defined as a bamboo which has a dbh of 2 cm and above and a height of 2 m and above. Therefore, bamboo culms measuring less than these measurements, if occurring in the sample area, were ignored from the analysis. Normally, areas having 1 to 2 year old bamboo vegetation were selected for collecting of data as they complied with FSI standard for their elegibility to be sampled and analyzed for the estimation of growing stock. As a whole, the total growing stock of the State was estimated to be 24.014 million metric tonnes out of a total bamboo.As a whole, the total growing stock of the State was estimated to be 24.014 million metric tonnes out of a total bamboo area of 7,091.66 km , which constituted 33.63% of the total geographical area of the State. The average growing stock was assessed to be around 3,386.25 metric tonnes per square kilometer. The total number of culms for the entire State was estimated to be 6,123.86 million. Area statisticsOut of the total bamboo area of the State (7091.66 km ), Lunglei has the maximum area of 1,956.59 km , followed by Mamit, Aizawl, Lawngtlai, Kolasib and Serchhip, respectively having 1,598, 927.69, 730.79, 661.80 and 439.08 km area under bamboo forest.
Champhai has the lowest area under bamboos (345.68 km )followed closely by Saiha district (432.04 km ). If we look at the percentage area of the district covered by bamboos, Mamit has themaximum percentage of its geographical area under bamboos(52.81%), followed by Kolasib, Lunglei, Serchhip, Saiha, Lawngtlai and Aizawl, respectively having 47.87%, 43.12%, 30.89%, 28.58% and 25.94% area under bamboos. The details are mentioned in Table 1.The division wise assessment of the bamboo area indicatedthat the maximum bamboo area is available in Thenzawl ForestDivision (972.32 km ), followed by Mamit, Lunglei, Kolasib and Darlawn Forest Division, respectively having 841.15, 742.39, 638.68 and 510.66 km area under bamboos. The statistics of the autonomous district council area indicated that the maximum area under bamboo forests is available in LADC (549.11 km ), followedby MADC and CADC, respectively having 438.09 and 174.60 kmarea under bamboo forests.
Growing stock and Culm statistics
The assessment (MIRSAC, 2008) indicated that Lunglei had the maximum growing stock of bamboos i.e. 6.109 million metric tonnes, followed by Mamit, Aizawl, Kolasib, Lawngtlai and Serchhip, respectively having 4.164, 4.004, 2.800, 2.661 and 1.720 million metric tonnes of bamboo available in these districts. Sahia and Champhai were having the lowest growing stock of 1.393 and 1.163 million metric tonnes, respectively.The culm statistics indicated that, Lunglei had the highest number of culms (1,557.85 million culms), followed by Mamit, Aizawl, Kolasib and Lawngtlai, respectively having 1,061.84, 1,020.94, 714.10 and 678.49 million bamboo culms. Sahia and Champhai were having the lowest number i.e. 355.29 and 296.64 million culms, respectively. The details have been mentioned below in Tables 2 and 3.