Growth and Nutrient Response to Phosphorus Addition of Different Modified Tree Species in Acacia mangium Plantation

Abstract:

Acacia mangium is an important fast-growing tree in South China, but mature forest shows phosphorus deficiency which may reduce forest efficiency, so it needs to be reconstructed. Phosphorus, including four levels as control treatment (CK), low phosphorus addition (LP), medium phosphorus addition (MP), and high phosphorus addition (HP), were added into two forest reconstruction mode, such as M1 (Ormosia pinnata + Castanopsis hystrix + Cinnamomum camphora + Magnolia glauca) and M2 (Michelia macclurei + Carallia brachiata + Schima superba + Mytilaria laosensis) in a mature A. mangium plantation of Longyandong Forestry Farm of Guangdong Province. The growth and leaf nutrients of the modified tree species were measured after 39 months. The results showed that the total biomass of M1 species was the highest in MP (29.91 kg), and that of M2 species was the highest in HP (29.98 kg). The biomass of Michelia macclurei, Carallia brachiata and Mytilaria laosensis was the highest in HP, which was 5.97, 10.3 and 10.69 kg, respectively. The biomass of Ormosia pinnata, Castanopsis hystrix and Magnolia glauca was the highest at MP (5.12, 6.91 and 11.46 kg, respectively), the biomass of Cinnamomum camphora was the highest at LP (10.4 kg), and the biomass of Schima superba was the highest at CK (4.45 kg). The average phosphorus content of leaves of M2 species was higher than that of M1, but the average N:P in leaves of M2 species was lower than that of M1. Therefore, the phosphorus addition increased the phosphorus content and decreased N:P in the leaves of all modified tree species, which provided a scientific reference for the phosphorus addition gradient and the selection of modified tree species in mature A. mangium plantations in South Asia.

Key words:Acacia mangium;Plantation;Phosphorus addition;Forest reconstruction;Tree species growth;Leaf nutrient