Restoration of Water Storage Potential in a Degraded Dry Dipterocarp Forest with Enrichment Planting of Three Needle Pine (Pinus kesiya Royle ex Gordon), Northern Thailand

Abstract

The research assessed water storage in a dry dipterocarp forest (DDF) with enriched 34-year-old pine planting and the role of pine. Plant surveys were carried out using 10, 40×40 m2 plots, and data were obtained by measuring tree stem girths and heights. Plant features, biomass, and stored water amounts were measured. Fresh plant samples of abundant species were taken one time per month from January to December 2018. Three soil pits were made in three plots, and soil samples along 100 cm depth were taken on the same days of collecting plant samples for studying fied capacity, water content and water amount. The DDF was divided into three stands based on the most dominant tree species; Shorea obtusa, Dipterocarpus tuberculatus, and Dipterocarpus obtusifolius. The forest was composed of 86 species with biomass at 101.62 Mg/ha and contained an average water amount of 88.01 m3/ha. The water amount in biomass varied with sampling times from 58.74 to 111.83 m3/ha. The average MWHC of 100 cm soil was estimated to be 5,113.74 m3/ha. The water amount in soil also varied with sampling times from 3,651.50 to 4,481.06 m3/ha. As a result, the total water amount in plant biomass and soil (ecosystem) of the DDF varied in a range from 3,735.0 to 4,558.67 m3/ha. The pine contributed to 30.87 m3/ha (35.07% of the total) and could increase by 64.92% the water storage potential of the forest, and thus these results support the concept of pine enrichment planting in the poor DDF.