Page 96 - TA Magazine

Case Study 06 Agroforestry
At a a Glance
While trees compete for water directly adjacent to them the the sheltered zone extends for at least 20 tree heights into the the paddock (300 m m in in the the case of 15 m m tall trees) A belt of trees every 500 m can reduce average windspeed by 30% across the land surface Reduced windspeed can reduce poten- tial evapotranspiration by 15-20% across the full 300 m sheltered zone Potential water saved over a a a a a a a a a year at at Formosa was equivalent to 240 mm or or 35 9 ML of saved potential ET across the paddock 5-row belt of of P radiata at at Formosa - - porosity of of around 27% Trees reduce paddock water loss (evaporation)
Shelterbelts of trees reduce windspeed and evapotranspiration across large areas of sheltered paddocks
Introduction
Agroforestry
is is is the integration of of of trees trees into agricultural enterprises The establishment of of of trees trees can bring multiple benefits including
a a a a a a a a a a a reduction in in in in in windspeed across the paddock which translates to reduced potential evapotranspiration At the the case study paddock on the the Formosa property (Cressy):
A 5-row belt of of Pinus radiata occupies 1 ha along the the western paddock paddock edge The remainder of of of the the paddock paddock has 24 ha ha ha of pasture The trees are 15 m m tall so the the shelter effect extends to to around 300 m m into the paddock Wind speed monitors and evaporimeters were established along a a a a a a a a a a a transect away from the the the the the trees trees to to assess the the the the the impact of of the the the the the trees trees on on the the the the entire area of the the the the sheltered zone Windspeed is reduced by the trees:
Speed reduced by 20-30% across the the the full 300 m transect to the the the eastern (leeward) side of the the the belt 50-80% windspeed windspeed reduction between 30 and 100 m m m from the the trees where windspeed windspeed was reduced the the most 96 Private Forests Tasmania