| Fuelwood species - Prosopis juliflora : |
These are spiny shrubs and trees, very variable, small to medium sized, aggressively fast growing, semi-evergreen to evergreen, large crowned, with drooping low branches, with bipinnate leaves, greenish-yellow flowers cylindrical or flat and flowering almost throughout the year. The species include several varieties and forms; two important and well-known varieties beside chilensis are velutina and glandulosa. Six species are reported in India; Prosopis cineraria is indigenous and others have been introduced. Prosopis chilensis , an American species , and its variety glandulosa have run wild in many parts (CSIR, 1990).
When the growth of Prosopis juliflora is disturbed like hacking or cutting axillary bud becomes more active than the terminal bud and start producing innumerable number of branches. So the tree attains more bushy form or shrub like instead of a tree. But if left undisturbed it can grow to a tree form even with a girth at breast height of more than 100 to 200 cm. Prosopis grow well in basic soils like the black cotton soil and hence widely distributed in black soils of Andhra Pradesh and northern Karnataka. It prefers plain land soils, instead of hilly soils as the latter have less surface soil volume. It prefers soils well drained but can't survive in deep standing waters. The best example is Bychapura lake ( in Gauribidanur taluk) where the stagnant water show poor or no growth compared to wet, but well drained soil.
Prosopis juliflora attains the highest Mean Annual Increment (MAI) and the Current Annual Increment(CAI) reaches a peak on six year old stands ( Garg, V.K. 1999). This shows six year stand is an optimum age for harvesting Prosopis juliflora. In six year stand, the above ground biomass production is about 57 ą 3.5 t/ha and mean annual litter productivity is about 7.4ą1.13 t/ha. In many villages of Gauribidanur taluk, Prosopis juliflora is preferred for fuelwood due to its calorific value, higher growth rate, cycling time of six years (comparable to any other fuelwood species), coppicing power and its capability to produce more extensive root system and deeper penetration to rehabilitate sodic soils more effectively.
