Abstract:
In this study I investigated the presence and distribution of arbuscular mycorrhizal fungi (AMF) in soils of agricultural lands in the Auckland/Northland region, and explore the possibilities of how such information can be used to enhance the success of re-vegetation projects. AMF are a vital root symbiont for most woody species. The experimental part of the study is divided into two parts: the Pilot Study and the Main Study. The purpose of the Pilot Study was to investigate various methods of AMF detection, and to establish the methods and the experimental design for the Main Study. The Main Study was set up to investigate the null hypothesis that the distribution of AMF is the same in the forest as in the adjoining agricultural landscape. I compared the distribution of AMF in five locations where intensive agricultural land adjoins remnant Northern forests dominated by broadleaf / podocarp tree species. At each five sites, soil samples were taken along three 50 m long transects starting from the edge of the forests into the agricultural land. The soil samples were used to set up bioassays with (Zea mays) as trap plants. The grid intersect method was used for quantitative estimation of AMF from the maize roots after staining with trypan blue. The highest amounts of AMF were found at 5 m and 10 m distances from the forest edge, while lowest amount of colonisation was detected at 50 m at every location. Samples taken from the forest showed low values of AMF availability. It was concluded that effects of agricultural activities such as grazing, compaction and fertilisation decrease AMF availability. The abundant presence of AMF close to the forest edge could be utilised in revegetation projects. However, revegetation in retired farmland, at a distance from forest remnants may present a more challenging soil environment, if AMF are lacking. Further work is needed to establish whether the potential lack of AMF in retired agricultural land may be detrimental to revegetation projects in these environments. This study can be extended by incorporating other possibly important factors such as soil phosphorous content and AMF communities composition.