Soil nutrient differences between two krummholz-form tree species and adjacent alpine tundra

Abstract

Above treeline at Goliath Peak, Colorado, Pinus aristata (bristlecone pine) and Picea engelmannii (Engelmann spruce) grow as krummholz tree forms. Due to the harsh alpine climate, these trees are dwarfed in size (approximately 0.5 to 3.0 m tall) and root along a horizontal stem. Soil nutrients, including carbon, nitrogen, and phosphorus fractions were examined to 10-cm depth beneath P. aristata krummholz and P. engelmannii krummholz, as well as from adjacent, undisturbed alpine soils. Plant available phosphorus was higher under P. engelmannii than P. aristata, suggesting that although these two species exist in the same environment, they have a different effect on the availability of labile soil phosphorus. Mineral soils under P. aristata were not significantly different than under P. engelmannii for total carbon, total nitrogen, and total phosphorus. Soil phosphorus differences are important in this ecosystem because of the proposed P limitation in some alpine ecosystems.