Climate-growth relation and isotopic 13carbon responses of field-grown Pinus caribaea var. hondurensis and Pinus taeda to nutrient availability

This study aimed to characterize the development of Pinus caribaea var. hondurensis and Pinus taeda grown under two fertilization regimes (fertilized and control treatments) at field-grown condition. The growth, climategrowth relation, and intrinsic water use efficiency (WUEi) of the trees were assessed by a combined analysis of cross-sectional area (CSA) increment, water balance and carbon isotope discrimination (Delta 13C parts per thousand). The effect of fertilization on tree growth regime was assessed using inventory data collected yearly over 8 years. Additionally, monthly data of wood increments, monitored in nonfertilized stands over a period of 6 years, were utilized for correlations with meteorological variables (air temperature, rainfall, vapor pressure deficit, solar radiation and potential and actual evapotranspiration). The growth of Pinus caribaea and P. taeda was strongly influenced by multiple meteorological variables related to water availability and evapotranspiration. Differences in carbon isotope composition between treatments revealed that fertilized Pinus spp. displayed higher Delta 13C values in some years, indicating improved water uptake efficiency due to increased nutrient availability. Pinus caribaea outperformed P. taeda in wood productivity and exhibited a heightened responsiveness to fertilization. In general, P. caribaea was shown to be more water-use efficient than P. taeda, as it is able to use smaller amounts of water for greater wood production.