Making the most of vegetation
What trees can do for you…
Trees can improve agricultural production by providing shade and shelter that protects stock and crops from wind and extremes of heat and cold. Vegetation contributes to an effective water cycle. Together with extensive, slow biodegrading litters, diverse woodland communities reduce surface wind speeds and extreme temperatures that would otherwise encourage significant evaporation losses.
Studies on a wide range of sites have shown that shelterbelts can improve crop productivity, typically by 5% to 20% . Trees established as shelterbelts and woodlots can be managed to produce timber and other tree products, thus increasing diversification of farm income . Experiences of our case study participants have further demonstrated the benefits of tree regeneration and/or revegetation.
On Dukes Plain near Theodore in Queensland, Shane Joyce is measuring the financial benefit of increased vegetation in his pastures. Shane has found that paddocks with regenerated stands of brigalow (Acacia harpophylla) support higher production (a gross margin of $112.74 ha/year) compared with those that had been cleared (gross margin of $83.96 ha/year).
Shane’s own observation and monitoring on Dukes Plain identified the importance of shelterbelts and tree canopy levels in relation to production, as well as for regeneration of natural resources.
Shane observed a balance between sunlight reaching the grass understorey for photosynthesis and the benefits to that understorey of having shade during hot periods when photosynthesis would otherwise shut down. He noted that shelterbelts also provide protection from wind shear on both moisture loss and animal performance in cold, as well as a barrier to frost impact on leaf production. As trees have deeper roots, they also intercept nutrient from depth, recycling to topsoil and subsequently grass production via fallen leaf and residues.
Shane Joyce experimented with both narrow (left) and wide (right) shelterbelts to identify what would optimise production.
The Joyces observed that approximately a 40% canopy provided optimum pasture production for them. This is not a fixed ratio and will change from area to area relative to seasonal values of temperature, wind and rainfall frequency. The optimum level will vary from farm to farm - and is an area that can be investigated to maximise individual outcomes.
Increase productive land…
As discussed in an earlier post, on Talaheni, John and Robyn Ive are using revegetation to capture rainfall higher in their property to lower the water table and subsequently reduce salinity problems. As a result, saline seeps have been all but eliminated across their property, making much more productive land available.
The Ives have used innovative techniques, employing strategic grazing to exploit variable seasonal conditions, and using livestock to disturb hard ground surface to facilitate germination. Combined with additional manual planting, the Ives estimate they have established more than 200,000 trees on their property. The result of their actions are clearly visible along their boundary line in the image below.
Just some of the benefits that can be obtained by regenerating vegetation and making it work for you!
The Soils for Life Team
1 Cleugh, H., 2003, Trees for Shelter: a Guide to Using Windbreaks on Australian Farms, RIRDC Publication 02/059, Rural Industries Research and Development Corporation, Canberra.
2 Fritsch, S. and Hudson, B., 2008, Whole Farm Financial and Environmental Returns Under Farm Forestry: Six case studies, RIRDC Publication 08/146, Rural Industries Research and Development Corporation, Canberra.