EFFECTS OF FERTILISATION ON SOIL NUTRIENT CHARACTERISTICS AND THE GROWTH OF TREE STAND IN SECONDARY SEASONALLY DRY TROPICAL FORESTS IN MEXICO

Soil properties and stem growth were studied in dominant tree species in secondary tropical dry forests growing on limestone in Yucatán Peninsula, México. A young forest (10 years old, site A) with phosphorus (P)-poor soil and an older forest (60 years old, site B) with soil having higher available P contents were selected. Tree growth of representative species of each site was studied in relation to soil nitrogen (N) and P concentrations. Four independent plots (12 m × 12 m) in each forest were either left intact (controls) or fertilised with N, P or with N + P for three years. In the young forest soil concentrations of NO3 - were higher than those of NH4 +, indicating that nitrification proceeded fast. Application of N and N + P increased the concentration of soil NO3 - at site A; fertilisation treatments at this site increased trunk growth only in Lysiloma latisiliquum. In contrast, N or P fertilisation at site B did not significantly affect soil extractable N concentrations. At this site, fertilisation increased N transformations and P addition promoted growth in Acacia gaumeri and Bursera simaruba. These findings indicated that nutrient limitation occurred in the secondary forest.