Biomass production of trees and grasses in a silvopasture system on marginal lands of Doon Valley of north-west India. 1. Performance of tree species |
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| Authors: | M K Vishwanatham J S Samra A R Sharma |
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| Institution: | (1) Central Soil and Water Conservation Research and Training Institute, Dehradun, 248 195, India |
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| Abstract: | Bouldery riverbed lands occupy about one-third of the geographical area in Doon Valley of north-west India. These marginal
lands need rehabilitation through establishment of silvopasture system for meeting the biomass requirements of resource-poor
farmers. A study was carried out for 14 years (1980 to 1993) at Dehradun, involving four multi-purpose tree species viz. Albizia
lebbek (L.) Benth., Grewia optiva Drumm., Bauhinia purpurea L. and Leucaena leucocephala (Lamk.) de Wit.; and two grass species
viz. Chrysopogon fulvus (Spreng.) Chiov. and Eulaliopsis binata (Retz.) C.E. Hubb. Fifty and 75% of the tree crown was lopped
once a year after four years of age. Tree survival decreased with age, and was highest with L. leucocephala (86.9% in 1993
of initial density of 625 trees ha−1) and lowest with B. purpurea (49.3%). Canopy parameters of trees progressed differently, presumably due to their varying
growth habits. The trees of A. lebbek were taller with more crown spread, whereas G. optiva had more crown height with lesser
crown spread. Stem diameter growth of A. lebbek was highest followed by B. purpurea. Lopping intensity did not affect tree
survival and also canopy growth in most years, but collar diameter and diameter at breast height (dbh) decreased significantly
at the higher intensity of lopping. Intercropped grass species E. binata caused a greater adverse effect on the tree survival
and growth parameters than C. fulvus. The biomass production (leaf and branch wood weight of lopped material) was highest
at eight years of age in 1987 but showed no definite trend over the study period. Bauhinia purpurea produced the highest biomass
and L. leucocephala the lowest, despite opposite trends in their survival. The performance of A. lebbek was on par with B.
purpurea in the later years (1990--1993), but G. optiva was inferior despite its superiority in the early years (1984--1985).
The effects of lopping intensity were not appreciable, but intercropping with E. binata decreased leaf and branch wood production
significantly compared with C. fulvus throughout. However, the adverse effect was comparatively less pronounced on B. purpurea
and A. lebbek than on G. optiva and L. leucocephala. The fibre yield of G. optiva also decreased due to intercropped E. binata
compared with C. fulvus.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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| Keywords: | bouldery land branch wood intercropped grasses leaf dry weight multi-purpose trees tree lopping tree-grass interaction |
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