Ecological Accommodation of Soil Hydraulic Properties Driven by Industrial Reforestation in Central Chile

Soil hydraulic properties (SHP) are among the indicators of the diversity and health of an ecosystem and are commonly measured by two criteria: infiltration and water retention capacity. By “Ecological Accommodation” we mean the sum biological and non-biological processes which modify the SHP, including bioturbation and the accumulation of organic matter.   Central Chile is at the tail end of massive land use/land cover transition from several hundred years of wheat cultivation (annually tilled) to short rotation (25-30 yr) silviculture. This allows for neighboring assessment of soil impacts of transitioning sites from cultivated to uncultivated production as a function of time.  Further, the region’s climate geography (a North-South primary axis) allows us to view the soil health impacts of this change in planting along a precipitation gradient (700-1700 mm/yr) to help tease-out the impact of climate on temporal dynamics of soil properties.   We measured infiltration in five recently transitioned first rotation locations along this precipitation gradient.  Sampling plots were established for continuous wheat, early-, mid-, and late-stage pine plantations, and Chilean Native Forest. With preliminary analysis of the dry season measurements, we found transitions from wheat to silviculture saw an initial decrease in infiltration (~30% over 10 yrs); however, over time (~30 years) infiltration in the plantations approached that of the Native Forest (increasing by ~500%). These findings suggest that approximately three decades are required for the soil characteristics to transition between annually tilled versus untilled properties (tending to increase infiltration capacity).