MOUNTAIN RESEARCH AND DEVELOPMENT; Vol.30 3; 232-243
Direct seeding has recently regained favor as an alternative method to conventional planting for restoration of degraded and/or abandoned sites. This study reports the establishment and growth performance of 2 pioneer (Pinus kesiya and Schima wallichii) and 2 later-successional (Keteleeria evelyniana and Quercus serrata) native trees broadcasted or buried on 14 former grazing lands in Laos. Seedling establishment was assessed 9 months after sowing; height, diameter growth, and mortality were measured 1, 3, and 5 years after direct seeding and subjected to analysis of variance. Significant interspecies and intersite variations were detected for most of the measured parameters (P < .05). Seedling establishment success was better for buried seeds of Q. serrata (49-65%) and K. evelyniana (20-59%) than for broadcasted seeds of P. kesiya (13-50%), S. wallichii (3-34%), and K. evelyniana (6-22%). Intersite variation might be related to topography-induced microhabitat conditions. The annual rate of mortality, averaged over all sites, was significantly (P < .0001) high for S. wallichii (38 +/- 1%) followed by P. kesiya (30 +/- 2.0%), Q. serrata (29 +/- 2%), and K. evelyniana (22 +/- 4%). The 2 pioneer species achieved better diameter and height growth than the later-successional species. We conclude that direct seeding seems to be possible for rehabilitation of abandoned sites, provided that the seeds are buried to avoid the risk of seed desiccation and predation; the seeding rate of pioneer species is reduced to avoid a high mortality rate, and species-site matching is well defined to minimize topography-induced changes in a microhabitat.