Effects of nurse trees, fertilizer and mulch treatments on the growth performance of interplanted white Lauan (Shorea contorta (Vidal) Merr. and Rolfe) seedlings

Height and diameter increments of white lauan seedlings at the end of the study showed significant difference due to pioneer species and fertilizer treatments. Seedlings grown under the kakawate [Gliricidia sepium] had greater height and diameter increment than the control (no pioneer species). Similarly, fertilized seedlings had significantly greater height and diameter increments than unfertilized ones. On the other hand, although mulched seedlings had greater height and diameter increments than those unmulched, the differences were not statistically significant. Mortality of white lauan seedlings was evident starting the 6th month. On the 12th month, percentage survival was significantly affected by the pioneer species treatment but not by the fertilizer and mulch treatments. The survival percentage of white lauan planted under kakawate was 87.50%; followed by those planted under dapdap, 80.80%; and under control, 76.70%. Results, therefore, indicate that white lauan significantly responded to nurse trees and fertilization in terms of growth. But in terms of survival, white lauan significantly responded only to nurse trees. Kakawate as nurse tree is better than dapdap and the control because it gave better survival and growth of white lauan. All the treatments had no significant influence on the soil moisture content, organic matter, nitrogen and pH. Air temperatures under the pioneer species were significantly lower than in the control at the initial, 3rd and 6th month. However, on the 9th and 12th month, air temperatures did not differ significantly. Soil temperatures were significantly lower on those mulched seedlings than those unmulched. Soil temperatures were significantly lower under the pioneer trees than those in the control treatments in the initial and 9th month but not in the 3rd, 6th, and 12th month. The amount of soil phosphorus and potassium were significantly greater in the fertilized seedlings at the end of the study.