Effects of silvopastoral practices on intensively-managed quality timber plantations in Spainwca2014-1941 Gerardo Moreno 1,*María L. López-Díaz 1Manuel Bertomeu 1 1Forest Research Group, University of Extremadura, Plasencia, Spain
Europe needs high quality wood. A number of several thousand hectares of hardwood plantations have been established in many regions of the Iberian peninsula. To enhance tree growth frequent harrowing and high levels of water, fertilizer and herbicide inputs are commonly applied. Silvopastoral management could reduce the economic costs and the negative environmental impact of these plantations.
We evaluate the response of intensive irrigated walnut (Juglans major var. 209 x Juglans regia) and wild cherry (Prunus avium) plantations to: (i) alternative methods of controlling the competing herbaceous understory (harrowing, brushcutting, and grazing), and (ii) the substitution of mineral N fertilization by sowing leguminous pastures (which would also reinforce the pastoral value of the system).
After 12 years of intensive management, the change to alternative management had slight but significant effects on tree growth. Both fertilized and legume-intercropped trees grew similarly and faster than control trees in spite the yield of herbaceous understory almost doubled in both cases respect to control ones (3652, 3564 and 1978 kg DM ha-1, respectively), and consequently soil moisture was reduced with both treatments. Nevertheless, this had not any significant effect on water status and photosynthetic activity of walnut leaves. By contrast, both fertilized and legume-intercropped walnuts had leaf N content slightly higher than control trees.
Grazing did not affected significantly to soil moisture, tree water status, soil nutrient availability or leaf nutrient content, but reduced significantly the growth of trees compared to brushcutting and harrowing. These results agree with the marginal decrease of CO2 assimilation rate of walnut leaves in grazed plots. We expect that with more time a more regular grazing will reduce differences among grazed plots and mechanically managed ones.