Effect of water-table depths and groundwater salinities on the growth and biomass produdion of different forest species

Abstract

A study was conducted during 2002-06 at the Central Soil Salinity Research Institute, Karnal in large lysimeters made of hume pipes, 2.5 in deep and 1.2 m internal diameter to find the effect of different water-table depths and groundwater salinities on biomass production of different species. The effect of 3 water-table depths (1.0, 1.5 and 2.0 m) and 5 levels of the groundwater salinity [ 0.4 (control), 3, 6, 9 and 12 dS/m] was evaluated on the growth and biomass of 4 forest species, viz kikar [Acacia nilotica (L)], shisham (Dalbergia sissoo Robx), casuarina (Casuarina glauca Sieb ex. spreng) and jamun [Syzygium cumini (L)]. Among the 4 species evaluated casuarina, followed by kikar and shishum showed highest growth and biomass production after 4 years. Kikar was sensitive to shallow water-table depth and high groundwater salinity. Height and girth of kikar plants decreased with increase in groundwater salinity, the maximum reduction being at groundwater salinity of 12 dS/m. In shisham, after 4 years of growth there was 100% mortality at groundwater salinity of 12.0 dS/m, indicating that it was very sensitive to shallow water-table depth with groundwater salinity. As the age of the plants advanced, adverse effects of shallow water-table depth on height and girth also started appearing in shishum species. There was no significant effect of water-table depth and groundwater salinity on the growth of,jamun up to third year of growth. Casuarina plants not only tolerated shallow water-table depth of 1.0 m and higher groundwater salinity of 12 dS/m but also showed the maximum growth under both the conditions. It also did not show any toxicity symptoms due to high salts present in the groundwater. The results showed that kikar and shisham are sensitive to both shallow water-table depth and groundwater salinity and should not be planted where groundwater salinity is more than 3 dS/m and water-table is shallower than 2.0 m. In areas prone to waterlogging and high groundwater salinity, casuarina followed by jamun is the best tree species for afforestation. Overall, the tolerance to groundwater salinity was of the order of casuarina &gt .jamun &gt kikar&gt shisham; and to water-table depth as casuarina &gt jamun &gt shisham &gt kikar. Absolute wood production was also greatest in casuarina compared with the other species.