Liana density declined and basal area increased over 12 y in a subtropical montane forest in Argentina

Abstract

Changes in density and basal area of lianas ≥2 cm diameter were monitored in two 1-ha permanent plots in a subtropical montane mature forest of north-western Argentina. Liana stems were identified and measured at 130 cm from the main rooting point in two censuses conducted in 2003 and 2015. Between censuses, the density of liana stems decreased 13.3%, while basal area increased 11.5%. Density and basal area decreased mainly among lianas of 2-3 cm diameter, but increased in lianas ≥4 cm diameter. Quechualia fulta (Asteraceae), Serjania meridionalis (Sapindaceae) and Chamissoa altissima (Amaranthaceae) suffered large reductions in stem density and basal area. Dissimilar responses of density and basal area of lianas might be a consequence of the suppression of anthropogenic disturbances (e.g. livestock browsing) and the decrease of treefall gap frequency in the studied forest in recent decades. Light-demanding liana species decreased and shade-tolerant species increased possibly in response to the decline in the light availability associated with forest recovery from past disturbance. Lianas increased in basal area to a lesser extent compared with reports from several tropical and subtropical forests where lianas are increasing dramatically.