Evaluation of the Effects of Pine Management on the Water Yield and Quality in Southern Brazil

We evaluated the effects of pine (Pinus taeda L.) thinning and clear-cutting on the water yield and quality of three micro-watersheds from southern Brazil using paired- (reference site) and within-site (pre- and post-management periods) comparisons between 2013 and 2016. We inspected for differences in topographic and remote sensing data between the reference site 1 (native forest) and the managed sites 2 (thinning) and 3 (clear-cutting). Double-mass analysis and analysis of covariance (ANCOVA) were used to evaluate rainfall across sites. Using physicochemical data, we calculated the Water Quality Index (WQI) and measured the water yield, detecting anomalous events with wavelet transform. Finally, we verified differences across- and within-sites in median values of yield and WQI using the non-parametric Mann-Whitney test. The results from paired- and within-site comparisons showed that the management practices did not control the water yield and quality of the three studied micro-watersheds. Statistically significant differences in water yield and WQI were observed between the reference site 1 and pine-planted sites only in the pre-management period. Our findings showed slight differences across sites in morphometric parameters of the watersheds. The ANCOVA confirmed the importance of rainfall in controlling the variability of water yield over the thinning and clear-cutting sites.

Automated summary

The study found that thinning and clear-cutting of pine trees did not significantly impact the water yield and quality of the three micro-watersheds in southern Brazil, with only significant differences observed between the reference site and pine-planted sites in the pre-management period. Rainfall was confirmed to be important in controlling the variability of water yield over the thinning and clear-cutting sites.