Impacts of stand transformation on soil chemical properties and enzyme activities in a Pinus caribaea stand

Objective  Stand transformation was studied in a Pinus caribaea stand by introducing broad-leaved tree species to provide a scientific basis for rational management of P. caribaea stands.

Method  Castanopsis fissa, Acacia mangium, Artocarpus nitidus ssp. Lingnanensis and Camellia oleifera were planted among rows and lines of one part of the P. caribaea stand (P1), Schima superba, Symplocos lancifolia, Carallia brachiata and C. oleifera were planted among rows and lines of another part of the P. caribaea stand (P2), and one part of the remaining the P. caribaea stand was used as the control (CK). Five-point sampling method was used to collect soil samples from 0–20 and 20–40 cm depth soil layers respectively at three sample plots. Soil pH, organic matter, total nitrogen, total phosphorus, total potassium, alkalized nitrogen, avaiable phosphorus and avaiable potassium were determined by routine methods. Activities of catalase, phosphatase and urease were determined by colorimetry, disodium phenyl phosphate colorimetric method and titration with potassium permanganate, respectively.

Result  The contents of soil organic matter, total nitrogen, alkalized nitrogen and available phosphorus in 0–20 and 20–40 cm depth soil layers of three sample plots decreased in the order of P2, P1 and CK. The soil nutrient contents in 0–20 cm depth soil layers of the three sample plot was significantly higher than those in corresponding 20–40 cm depth soil layers. The total phosphorus contents were low in 0–20 cm depth soil layer of three sample plots, and the content of soil total potassium decreased in the order of CK, P1 and P2. Soil catalase activity was significantly related to pH and the contents of organic matter, total nitrogen, alkalized nitrogen, total potassium and alkalized phosphorus.Phosphatase activity was significantly related to pH and the contents of organic matter, total nitrogen, alkalized nitrogen, available phosphorus and total potassium. Urease activity was significantly related to soil contents of organic matter, total nitrogen, total phosphorus, alkalized nitrogen, avaiable phosphorus and avaiable potassium.

Conclusion  Stand transformation significantly improved the soil fertility of P. caribaea stand. The effect of mixed pattern at P2 plot was better than those at P1 plot . Mixed pattern at P2 plot can be used in stand transformation.