What is the Major Cause of Pinus taeda Nutritional Disorder in Southern Brazil?

Pine (Pinus taeda) forests exhibiting the nutritional disorder of foliar chlorosis and tree death following abrupt climatic events have been reported by the southern Brazilian forest industry in recent years. The goal of this study was to evaluate pine sites exhibiting chlorotic symptoms previously noted by forest companies.

Five pairs (control and chlorotic areas) of forest sites of similar age were selected for sampling and analysis of soil, root, litter, needle, and timber disc samples. Soils were developed from igneous (four sites) and sedimentary (one site) parent source materials.

On igneous derived soil, areas with chlorotic symptoms had higher soil fertility and plant tissues (needle, wood, and bark) with higher nutrient concentrations than control areas. Plant tissue concentrations of manganese (Mn) and calcium (Ca) were higher for chlorotic areas and needle chlorosis was characterized by basal paling of needles. The limiting factor related to chlorosis could not be definitively determined. On sedimentary derived soil, chlorotic areas had low soil fertility, lower tissue nutrient concentrations, particularly magnesium (Mg), and needle tip chlorosis. There was no difference in litter biomass between chlorotic and control areas.

Findings suggest two distinct conditions promoting pine chlorosis in southern Brazil: high fertility soils may be nutritionally imbalanced due to high levels of Mn and/or Ca; and low fertility soils resulted in a deficiency of Mg.