Long term monitoring system integrated in an elevational gradient in NW Argentina

CARILLA, JULIETA; MALIZIA, AGUSTINA; OSINAGA, ORIANA; BLUNDO, CECILIA; GRAU, HECTOR RICARDO; MALIZIA, LUCIO; ARÁOZ, EZEQUIEL; GRAU, ALFREDO

Cancun

Congreso; AGU Meeting of the Americas; 2013

AGU

Ecological trends and ranges of variability are poorly known in the tropical and subtropical Andes.Long term studies are powerful tools to detect the response of vegetation dynamics, biodiversity and hydrological cycle to these trends. We present a long term monitoring system in NW Argentinean mountains, including forest permanent plots at different elevations and high elevation grasslands, encompassing more than 3.000 m elevation range. Long term studies include: 1) 66 ha of mountain forest permanent plots along the Yungas elevational gradient from c. 400 to 2300 masl , and along a latitudinal gradient from -22° to -27° S, with 45 plots in mature forests and 28 in secondary forests originated in grazing, agriculture and selective logging; and including plots severely invaded by exotic species. Some of these permanent plots have achieved 20 years of monitoring and are included in the Red de Bosques Andinos a regional network created recently, together with c. 10 institutions and more than 130 (c. 120 ha) forest permanent plots from Argentina to Colombia Andes. 2) Two GLORIA (Global Observation Research Initiative in Alpine Environments) pilot sites, above 4000 masl with more than 150 species recorded, including one re-measurement (the first one in Argentina). This monitoring system is included in the international network of GLORIA and in GLORIA Andes (http://www.condesan.org/gloria), and 3) more than 15 satellite monitored high Andean lakes and a wide extension of vegas (75800 ha in Argentinean puna). A digital database (?Sistema de monitoreo ambiental - SIMA) is being implemented to organize and provide access to the information generated by these three systems coordinated by the "Instituto de Ecología Regional? (IER. http://www.iecologia.com.ar). These monitoring data are analyzed together with instrumental and dendrochronological data to describe the dynamics of these ecosystems oven an area of 20 million hectares distributed between 22 and 28 º S. . Some of the most significant results to date include; 1) secondary mountain forests are expanding over grasslands and agriculture lands, and tend to converge toward mature forest composition over time, despite different previous land use. Floristic changes are also reflected in structural changes, showing an increasing trend in basal area and biomass in the last 15 years for most of the plots. Exotic tree species are expanding their distribution (e.g. Ligustrum lucidum, from SE Asia) and have a strong influence on the structure and dynamics of some secondary forests2) High Andean vegetation diversity decrease with altitude, while several functional groups cover increase with temperature, which is also associated to mountain orientation. 3) There is a clear association between lake fluctuations, ecosystem productivity (EVI) and regional climatic patterns. The long term record provided by dendrochronology analysis showed that plant productivity of the last decades is the lowest in the last 180 years, with a consistent drying trend in the last years. We are generating longer temporal series of meteorological data and biological ecosystems measurements; this will help to differentiate between the effect of climate change, land use change and natural ecosystems variability, to understand the way vegetation and ecosystems response to these changes