Mineral nutrition and leaf longevity in an evergreen shrub, Ledum palustre ssp. decumbens.

Effects of variable mineral nutrient status on evergreen leaf longevity were investigated in a field fertilization experiment, and by comparison of plants from several sites. The species studied was Ledum palustre spp. decumbens, with a normal leaf life expectancy of 2.06 years and a maximum leaf longevity of 4.5-5.0 years. Most leaf losses took place during the growing season, not during the winter. Fertilization increased leaf production but decreased leaf survivorship. Total number of leaves per stem was unchanged with fertilization. In a comparison among sites, there was a moderate negative correlation between plant N and P concentrations and leaf longevity. These intraspecific responses are similar to known interspecific changes along nutrient gradients, i.e. with high nutrient availability a vegetation should become more "deciduous" and less "evergreen".