Diminishing the climate footprint with exotic pine afforestation in Patagonia, Argentina?

AUSTIN, AT

Dublin

Congreso; Next Generation Scientists Meeting, New Phytologist Trust; 2019

New Phytologist Trust

Land-use change, including the conversion of natural ecosystems to produce tangible products such as food or wood, is one of the most prominent manifestations of global change in terrestrial ecosystems. In particular, the planting of tree species in previously non-forested ecosystems to achieve rapid growth and potential carbon sequestration has become an attractive option proposed for long-term carbon (C) storage and climate change mitigation. Nevertheless, there are many open questions regarding how ecosystem processes are modified as a function of this land-use change. We took advantage of an unplanned natural experiment involving a 40-year-old forestation project, where a single conifer species (Pinus ponderosa), was planted regionally in Patagonia, Argentina, replacing natural ecosystems ranging from semi-arid steppe to broadleaf forest along a broad range of precipitation (250-2200 mm mean annual precipitation [MAP]). We evaluated the effects of this change in dominant vegetation on ecosystem C and nitrogen cycling, net primary production (NPP) and decomposition, and modification of the soil fauna. Taken together, our results suggest that a change in the species composition of the dominant vegetation was sufficient to modify the major drivers of C and N cycling in these sites independently of climate constraints. Alterations of ecosystem processes due to afforestation were sufficient to significantly diminish, if not erase, the climate footprint along this broad precipitation gradient.