The performance of Polylepis australis trees along their entire altitudinal range: implications of climate change for their conservation

Abstract

Altitudinal gradients are expected to heavily influence the general performance of mountain tree species. For this study we evaluated vitality, radial growth and reproductive efficiency in Polylepis australis (Rosaceae) throughout its complete altitudinal range in central Argentina. We selected seven forest fragments ranging from 900 to 2700 m a.s.l. In the field, we subjectively assigned vitality and seed productivity indexes to 12 P. australis trees per fragment. In addition, we cored and assessed for radial growth 10–18 trees per altitudinal level. In the laboratory, we individually weighed seeds from four or five trees from each altitudinal level and divided into two seed mass classes (light and heavy). We then tested for germination and monitored their seedlings for survival. Seedlings of three trees per altitudinal level were harvested after 40 days and assessed for dry mass. Seedlings of one to two trees per altitudinal level were monitored for survival until both leaves and roots had died. Our main results showed two types of responses to altitude: a unimodal relationship with an optimum at intermediate altitudes of around 1800 m a.s.l. for tree vitality, radial growth, seed productivity and seed mass; and an increase with altitude for in‐vitro seed germination and seedling survival. A rise in temperature due to climate change could restrict P. australis to the upper most altitudes, where conservation of these forests will be a priority.

Factors associated with woody alien species distribution in a newly invaded mountain system of central Argentina

“…The mean annual temperatures range from 13.2°C at 1,500 m a.s.l. to 7.4°C at 2,700 m (Marcora et al 2008). Mean annual precipitation is 924 mm, with most rainfall concentrated in the warmer months, between October and April (Cabido and Acosta 1985;Colladon et al 2009).…”

Genetic structure and diversity ofPolylepis australis(Rosaceae) tree populations from central Argentina: Implications for forest conservation

“…The mean annual temperatures range from 13.2°C at 1500 m asl. to 7.4°C at 2700 m (MARCORA et al, 2008). Mean annual precipitation is 924 mm, with most rainfall concentrated in the warmer months, between October and April (COLLADON et al, 2009).…”

¿Cuántos años monitorear el éxito de plantaciones con fines de restauración?: Análisis en relación al micrositio y procedencia de las semillas

“…La precipitación media anual es de 854 mm y la mayor parte (83 %) ocurre entre octubre y marzo. La temperatura media anual es de 8 ºC y no se registran meses libres de heladas (Marcora et al 2008).…”