Aim of study: This study aims at evaluating the impact of site preparation techniques prior to plantation on carbon
storage and distribution in a young mixed stand of Pseudotsuga menziesii (PM) and Castanea sativa (CS).
Area of study: The experimental field was established near Macedo de Cavaleiros, Northern Portugal, at 700 m
elevation, mean annual temperature 12°C and mean annual rainfall 678 mm.
Material and methods: The experimental layout includes three replicates, where the different treatments
corresponding to different tillage intensities were randomly distributed (high, moderate and slight intensity), in plots
with an area of 375 m2 each. Twenty six months after forest stand installation, samples of herbaceous vegetation (0.49
m2 quadrat), forest species (8 PM and 8 CS) and mineral soil (at 0-5, 5-15, 15-30 and 30-60 cm depth) were collected
in 15 randomly selected points in each treatment, processed in laboratory and analyzed for carbon by elemental carbon
analyzer.
Main results: The results obtained showed that: (i) more than 90% of the total carbon stored in the system is located
in the soil, increasing in depth with tillage intensity; (ii) the contribution of herbaceous vegetation and related roots
to the carbon storage is very low; (iii) the amount of carbon per tree is higher in CS than in PM; (iv) the global carbon
storage was affected by soil tillage generally decreasing with the increase of tillage intensity. Accordingly, carbon
storage capacity as affected by the application of different site preparation techniques should be a decision support
tool in afforestation schemes.
