Smt. Kalpana Palkhiwala writes: Eucalyptus has attracted attention from global development researchers and environmentalists. Outside of their natural ranges eucalypts are both lauded for its beneficial economic impact on poor populations and derided for being an invasive water sucker, leading to controversy over its total impacts and future. It is a fast-growing source of wood, its oil can be used for cleaning and functions as a natural insecticide, and it is sometimes used to drain swamps and thereby reduce malaria risk.
The meaning of Eucalyptus is “well covered”. It is known to attain heights over 100 metresand is described as the tallest of the flowering plants. There are more than seven hundred species of Eucalyptus, mostly native to Australia, with a very small number found in adjacent parts of New Guinea and Indonesia and one as far north as the Philippines islands. Species of Eucalyptus are cultivated throughout the tropics and subtropics including America, England, Africa, the Mediterranean Basin, the Middle East, China and the Indian Subcontinent. The first Forest Department Eucalyptus plantation was raised in 1887 at Malabavi (Devearayanadurga), Tumkur District.
Eucalyptus Raglans, known variously by the common names Mountain Ash, Victorian Ash, Swamps Gum, Tasmanian Oak or Stringy Gum, is a species description. Many, but far from all are, known as gum trees in reference to the habit of many species to exude copious sap from any break in the bark(e.g. Scribbly Gum). It is an evergreen tree, with a straight grey trunk, smooth bark except for the rough basal.
It occurs in cool, deep solid, mostly mountainous areas to 1000 m altitude with high rainfall. They grow very quickly, at more than a metre in a year, and can reach 65 metres in 50 years with an average life –span of 400 years. The fallen logs continue supporting a rich variety of life on the forest floor. Unusually for a eucalypt, the seeds are released from their woody capsules (gum nuts) by heat and for successful germination the seedlings require a high level of light, much more than what reaches the forest floor when there is a mature tree canopy. Competition and natural thinning eventually reduces the mature tree density to about 30 to 40 individuals per hectare.
Eucalyptus has multifarious uses viz. timber for construction, furniture, plywood paper and pulp, medicines, oil and fuel wood etc. It provides good ointment for the skin, containing antiseptic and healing properties. It produces very satisfactory results on, chapped hands, chafes, dandruff, tender feet, enlargements of the glands, spots on the chest, arms, back and legs, pains in the joints and muscles.
Eucalyptus Raglans and many other species are valued for their timber, and has been harvested in very large quantities. Primary uses are saw logging and wood chipping. It was major source of newsprint. Much of the present woodchip harvest is exported to Japan. It is a medium weight timber (about 680kg/m3) and rather coarse (stringy) in texture. Gum veins are common. The wood is easy to work and the grain is straight with long, clear sections without knots.
Productivity of Eucalyptus in India
The productivity of Eucalypt plantations varies considerably depending on the site, the edapho-climatic conditions and the inputs. The average productivity is around 7-6 cubic meters per hectare per year. The reasons for poor productivity are foliar blight disease caused by Cylindrocladium spp., hybrid breaking, close spacing, lack of availability of quality seeds, primitive nursery practices, mismatching of species and provenances’ to site and lack of follow up of correct package of practices. To raise the productivity of Eucalyptus plantations site and end-use specific superior genotypes for undertaking plantations have been identified. Significant gains in productivity of Eucalyptus have been achieved through vegetative propagation and cloning technique exploiting the existing useful variation.
Eucalyptus is generally raised by planting out nursery raised container plants. Seeds are generally mixed with sand and sown in the nursery beds. A thin layer of sand is spread over seeds. In Northern India, September – October and February-March are the main periods for sowing seeds in nursery beds. Germination commences in a week and completed in 2-3 weeks. When the seeds show second pairs of leaves above the cotyledons, they are ready for pricking out. Pricking out of seedlings is done into polythene bags.
Various methods of vegetative propagation are by lignotubers, air layering, grafting, rooting of stems cuttings and tissue culture. Suitable spacing for Eucalyptus plantation is adopted for planting. There is no significant difference in survivals under various spacing except at close ones. The planting time in India is governed by the onset of monsoon. However, closer spacing affects the productivity/hectare.
The State Forests Departments in Punjab, Haryana, Gujarat and Utter Pradesh manage Eucalyptus plantation at a rotation of eight years under simple coppice system. The farmers have brought down this rotation to 6 year and 4 year.
Recommendations of the Regional Expert Consultation
The main recommendations of the Regional Expert Consultation are to make provision in government’s policies for participatory approaches to forest plantation management and aims should be fixed for policies on manmade forests development. These aims are to meet the increasing demands for timber, fuel wood, fibre fodder, paper etc.(production issues), to reduce heavy pressure on natural forests (protection/conservation), to contribute to community development (social and economic issues) and to rehabilitate and restore damaged forests ecosystems in places where natural recovery cannot be foreseen in short period (environmental aspects).
The other consultations include review and updating of national land use and forest policies to ensure that these policies are socially fair, economically viable and environmentally sound, more freedom and responsibilities to local communities, user groups and private enterprise of various kind in the management of manmade forests, local communities should be encouraged to participate in plantation management and uses, encourage the producers of forest products to establish and strengthen cooperatives and other associations, special care should be given to adjust the eucalypt biomass production in the areas of scare water, operational adjustment under the integrated management of water soil cover, and nutrients in the surface soils or thinning of existing plantation, mixed plantation in under rain fed conditions etc.
Experts also recommend to leave the foliage and bark of eucalypts on the plantation floor after harvesting the wood, since these components have relatively high contents of nutrients. Soil nutrients balance and recycling efficiency should be continuously monitored from one harvest to the next. Eucalypt plantations should not be considered and used to replace healthy and undisturbed natural forests. If the conservation of biodiversity is a priority, the plantations may, however, have a value as buffer zones around nature conservation zones. It is further recommended to plant eucalypts in a mosaic fashion with native vegetation, where feasible. The tree breeding programmes should be strengthened, including the programmes undertaken by the private sector.
Besides these, Experts recommend to undertake certain research and development activities. They include site matching studies of species, provenances and varieties, studies on mixtures of eucalypts with other tree species and agricultural crops in various forms of land use, instead of, or as alternatives to, the monoculture of eucalypts, studies on nutrient cycling within poor soils vis-a-vis good soils, tree breeding programmes, leading to the production and supply of genetically improved seeds and vegetatively prepared planting materials, collection of growth and yield data on eucalypts and determination of their optimum stocking in order to monitor any adverse environment impacts caused by high biomass production or removals to reduce or avoid such adverse effects. Further studies have been recommended on social and institutional issues of eucalypt plantation, including forest policies, legislation, land tenure, and the roles of producers (farmers, government agencies and private companies) and local organizations in establishment and management of manmade forests, especially those composed of fast growing species (including eucalypts) and economic impacts of eucalypt plantations, including costs and benefits, product diversification (e.g. honey, essential oils, etc.) processing and marketing mechanisms.
Development of monitoring and evaluation systems to measure the social economic and environmental impacts of eucalypt plantations and to collect, evaluate, analyse and disseminate the research results and other relevant information on Eucalyptus species have been advised.
Water Use per Harvested Biomass in Respect of Eucalyptus viz Other Tropical Tree Species
(Litres/kg of total biomass or harvested commodity produced)
|plant||water use per total||Harvest index||Water use per harvested|
Source: Davidson (1989)