Five year growth and survival of <i>Eucalyptus</i> hybrid clones in coastal Kenya

Abstract

Twelve Eucalyptus hybrid clones (6 grandis-camaldulensis i.e. GC and 3
grandis-urophylla i.e. GU hybrids) and three local landraces (E. camaldulensis, E. tereticornis and E. urophylla) were established in Gede, Sokoke and Msambweni in the Coast province of Kenya in 2002, to compare growth, survival and adaptability in the three sites. By the end of the first year, trees in Sokoke were more than three times the mean height of those in Gede and Msambweni. However, these growth advantages during the first year in Sokoke were not maintained and by year 2 Gede had caught up, although Msambweni still lagged behind. By age 5 there were significant growth differences between clones. Of the tree sites, Msambweni had the lowest tree growth. GC167, GC14, GC581 and GC584 proved themselves as the better clones while E. camaldulensis and E. urophylla were the better local land races. Overall, the “local land races”
performed poorly in all sites. Survivals were over 80% in all sites for the  best performing clones. However, in Sokoke, one clone died (GU7) while another (GU8) had a survival of less than 20% while EC and ET had survivals less than 35%. GC796 died in Msambweni and had 8% survival at Gede. The poor survivals in Sokoke may have been due to a severe
drought in the third year. The initial outstanding growth performance in Sokoke may have been due to the fact that Sokoke was a ‘virgin’ forest site and presumably more fertile than the other two sites. These results
show that recommendations on outstanding clones or new germplasm for
planting or sale to farmers are best done at the end of the rotation for a particular intended product or use.

Key words: Eucalyptus hybrid clones, growth, site variation, weeding,
germplasm selection