Nutrient conservation strategies in native Andean-Patagonian forests

Abstract

Nutrient conservation in vegetation affects rates of litter decomposition and soil nutrient availability. Although resorption has been traditionally considered one of the most important plant strategies to conserve nutrients in temperate forests, long leaf life-span and low nutrient requirements have been postulated as better indicators. We aimed at identifying nutrient conservation strategies within characteristic functional groups of NW Patagonian forests on Andisols. We analysed C-, N-, P-, K- and lignin-concentrations in mature and senes- cent leaves of ten native woody species within the functional groups: broad-leaved deciduous species, broad-leaved ever- greens and conifers. We also examined mycorrhizal associa- tions in all species. Nutrient concentration in mature leaves and N- resorption were higher in broad-leaved deciduous species than in the other two functional groups. Conifers had low mature leaf nutrient concentrations, low N-resorption and high lignin/N ratios in senescent leaves. P- and K-resorptions did not differ among functional groups. Broad-leaved evergreens ex- hibited a species-dependent response. Nitrogen in mature leaves was positively correlated with both N resorption and soil N- fertility. Despite the high P-retention capacity of Andisols, N appeared to be the more limiting nutrient, with most species being proficient in resorbing N but not P. The presence of endomycorrhizae in all conifers and the broad-leaved evergreen Maytenus boaria, ectomycorrhizae in all Nothofagus species (four deciduous, one evergreen), and cluster roots in the broad- leaved evergreen Lomatia hirsuta, would be possibly explain- ing why P is less limiting than N in these forests.