The impact of widely spaced soil conservation trees on hill pastoral systems

An estimated 3.7 million ha or 33% of the North Island requires the application of significant soil conservation measures to be able to physically sustain pastoral enterprises. Traditionally, erosion control measures on hill farmland have centred on the planting of hardwood trees, such as poplars and willows, at wide spacings. Research and experience has confirmed that where hardwood trees are adequately planted and tended, they significantly reduce the magnitude of soil erosion and maintain soil stability. However, the effects that such erosion-control plantings have on pasture and animal production owing to changes in the farm microclimate, soil and water resources remains relatively unresearched in New Zealand. Keywords: hardwood trees, physical sustainability, silvipastoral systems, soil conservation</jats:p

Case study of a mature Populus deltoides-pasture system in a hill environment

Pasture characteristics, soil moisture relations and water balance were measured in open pasture and in a mature poplar understorey, to assess how land conservation practices modify a pastoral system. Mature poplars changed the environment of the understorey pasture, with light intensity decreased from September to April, and the soil generally colder and drier in autumn and early winter. Soil moisture relations did not suggest strong competition for water between trees and pasture in spring. Pasture under the poplars accumulated 40% less herbage mass and was of lower feed quality than pasture in the open. The case study highlights the complexity of silvipastoral systems in hill country and the need for a more complete understanding of the interactions if the potential of a multipurpose tree and livestock farming systems is to be realised. Keywords: conservation, pasture characteristics, poplar, Populus deltoides, sapflow, soil moisture, silvipasture, trees, water balance</jats:p