DOWNSLOPE EFFECTS OF CLEAR-CUTTING IN SWEDEN ON DIAMETER INCREMENT OFPICEA-ABIES AND PINUS-SYLVESTRIS

Swedish forestry handbooks recommend that strip cutting should be prac ticed on forested slopes, and that uncut buffer strips should be left between clear-cut areas and streams, because uptake by the remaining t rees is believed to prevent leaching of N to the streams. We have test ed this hypothesis using the assumption that, if it is true, these tec hniques should lead to increased diameter growth in the trees downslop e of the clear-cut because N is the growth-limiting nutrient in Swedis h mineral soils. Increment cores from trees growing downslope of 8-18- yr-old clear-cuts were studied, therefore, at five sites in northern a nd one site in central Sweden. Growth was not influenced by the cuttin g at any site for the first 3 yrs, and it increased at only two of the sites thereafter. The results indicate that stands left downhill of c lear-cuts do not always act as a catch crop for leaching N.