Impact of historical changes in land-use on the soil fauna

Replacing native forests and grasslands with plantations, pastures and crops has resulted in both contraction of ranges and exploitation of modified habitats by native species, and both general and restricted dispersal of introduced species of soil fauna. Contraction is shown by native earthworms, land snails, ring nematodes and various arthropods, while the areas with changed land use suggest certain native insects are more numerous than 150 years ago. Damage to pastures by grass grub and porina show clearly how native species can exploit modified habitats. Introduced Lumbricidae make a positive contribution to soil processes in pastures throughout New Zealand. The distribution of cyst nematodes reflects the distribution and intensity of cultivation of the hosts with which they arrived. Changes in soil structure, such as with the elimination or introduction of earthworms, can have marked effects on other soil structure, such as with the elimination or introduction of earthworms, can have marked effects on other soil animals. The faunal changes found are consistent with changes in land use; habitat protection for floristic and scenic reasons will help preserve both known and unknown elements of the soil fauna.