Chlorophyll–nutrient relationships identify nutritionally caused decline in Piceaabies stands

Abstract

Increasing needle chlorosis at a declining Piceaabies (L.) Karst. site in northeast Bavaria, Germany, as well as in other declining P. abies stands in southern Germany, was associated with a decrease in the concentrations of both chlorophyll a and b, and, to a lesser extent, of carotenoids. Needle chlorosis related more to a decrease in the chlorophyll concentration than to a decrease in the ratio of total chlorophyll to carotenoids. In forests growing on relatively acidified soils, concentrations of both chlorophyll a and b, and of carotenoids in chlorotic needles were related only to foliar magnesium concentration. In forests growing on more alkaline soils, chlorophyll concentration increased with potassium and phosphorus concentrations and decreased with calcium and magnesium concentrations. Green needles from a declining site in northeast Bavaria were also compared with those from a nearby healthy site. The chlorophyll concentrations in needles increased more at the healthy site than at the declining site during the growing season and with increasing needle age as predicted by a nutritional disharmony model. The use of foliar chlorophyll and nutrient analyses of needles representing a range in severity of chlorosis is proposed as a quick method of identifying the soil processes which, in some areas, cause forest decline.