Ecologically Driven Alteration of Soil Hydraulic Properties through mono-culture 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. 
This may be seen as an “Ecological Alteration,” resulting from the sum biological and non
biological processes which modify the structure of the soil, including bioturbation and the 
accumulation of organic matter. These changes in soil structure drive the changes in SHP.  

Central Chile has seen an abrupt and extensive 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 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 (850 – 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. We sampled in both the dry summer 
months and again in the wet winter months. In the dry sampling period, we found transitions 
from wheat to silviculture saw an initial decrease in infiltration; however, over time (~30 years) 
infiltration in the plantations approached that of the Native Forest (increasing approximately by 
an order of magnitude in 30 years). In the wet sampling period, the results were more 
inconclusive. Some plots did not show an increase in infiltration capacity while others showed a 
gradual increase over the same 30-year period.