『Abstract
Estimates of increased nutrient export caused by forest clear-cuttings
are mostly based on long-term paired catchment studies, where
the treatment effect is calculated using pre-treatment dataset
regression and post-treatment records of nutrient loads. In these
studies uncertainty in the regression between the pre-treatment
loads from the control and from the treatment catchments is typically
neglected, even though it affects determination of the magnitude
and duration of the treatment effect. This uncertainty is described
in terms of variance in regression coefficients and residuals.
The aim was to study how uncertainty in a pre-treatment dataset
is propagated to estimates of the treatment effects using two
sets of paired catchment data in eastern Finland, where the total
phosphorus loads following forest clear-cutting and site preparation
were investigated. The results showed that neglecting the uncertainty
in the pre-treatment data did not change the conclusions when
the treatment effect was strong enough. However, when the treatment
effect was small, neglecting the uncertainty in the pre-treatment
dataset easily leads to over-interpretation of the results. The
uncertainty in a pre-treatment dataset should be taken into account
in the paired catchment studies in order to avoid bias in the
estimation of management effects on the loads.
Keywords: Clear-cutting; Paired catchment; Phosphorus; Uncertainty;
Water protection』
1. Introduction
2. Material and methods
2.1. Murtopuro and Liuhapuro paired catchments
2.2. Kivipuro and Valipuro(aの頭に¨) paired
catchments
2.3. Runoff and chemical analyses
2.4. Regression analyses and estimation of treatment effects
2.5. Treatment of an outlier
3. Results
4. Discussion
5. Conclusions
Acknowledgements
References