An interdisciplinary study: farmers' knowledge of functional biodiversity and the effects of restored native vegetation on beneficial invertebrates in a pasture landscape

Abstract

There is a growing consensus among researchers for the need to conserve biodiversity within agricultural landscapes. Increasingly, research suggests that on-farm biodiversity is integral to the resilience and sustainability of agroecosystems. Biodiversity performs a range of ecosystem services in the agroecosystem such as regulating microclimates, recycling nutrients, augmenting soils, pollinating crops and supressing pest invertebrate populations. In particular, the role of invertebrate diversity in providing ecosystem services on farms is garnering much attention. Invertebrates comprise the bulk of faunal biomass on farms, are taxonomically diverse, and are the main drivers of many ecosystem functions. Globally, there are various practices and programs which are designed to increase biodiversity in agricultural landscapes. Often, these involve participation by farmers in projects which emphasize restoration of native vegetation (revegetation of land or protection of remnant native vegetation) on farmland. This study investigates the effect of restored native vegetation on invertebrate communities in southeastern Gippsland, in Victoria, Australia. In this project, restored native vegetation refers to both blocks of remnant vegetation and strips of land revegetated with native vegetation, both of which were protected by fencing from livestock. This study comprises a series of ecological assessments along with a social study of the role of farmers in championing and actioning conservation work within agricultural landscapes. The ecological component of the study was based on two broad taxonomic surveys of invertebrate abundances conducted on four farms and one reference site in the study area. Comparisons of invertebrate abundance were made at several taxonomic levels, across several vegetation types: restored native vegetation (either protected areas of remnant native vegetation or areas revegetated with native vegetation communities), pasture adjacent to restored native vegetation, pasture remote from native vegetation and a reference site. Groups of invertebrates considered to be beneficial to agriculture were of particular interest. At the order level, Araneae generally had higher abundances in restored native. Four (Asilidae, Tachinidae, Bethylidae, and Formicidae) of the 11 beneficial invertebrate families had higher abundances in restored native vegetation. One beneficial invertebrate family (Carabidae) had consistently higher abundances in pasture adjacent to restored native vegetation. The highest abundances of the other five beneficial invertebrate families (Lycosidae, Staphylinidae, Dolichopodidae, Syrphidae, and Apidae) showed no consistent pattern with regards to vegetation type. One beneficial invertebrate family (Xylophagidae) was only found in restored native vegetation. Thirteen of 16 genera of ants were commonly found to have higher abundances in restored native vegetation. Eight of the 16 genera of ants were found exclusively in restored native vegetation. Two out of the three functional groups consistently had higher abundances in restored native vegetation. When sampling of invertebrates was undertaken at different distances from the edge of restored native vegetation, decreases in abundance from the edge of restored native vegetation to 20m and 80m out into adjacent pasture were not uncommon for beneficial invertebrates. These results suggest that beneficial invertebrates may be using restored native vegetation as a faunal refuge. The reference site, a low-disturbance area, had unique invertebrate fauna, with high abundances of some beneficial groups. In addition, the cores and edges of areas of restored native vegetation had distinct assemblages of beneficial invertebrates compared to adjacent pasture. These results indicate that low-disturbance areas and restored native vegetation are important in increasing the abundance and diversity of beneficial invertebrates in a pasture landscape. Farmers in the research area were genuinely interested in restoring native vegetation on farmland. However, due to dry weather patterns in the research area, low commodity prices on the world market, and reductions in agricultural funding, farmers lacked the time and money to restore native vegetation on farmland. Lack of funding was most commonly identified by farmers as a barrier to restoration work on farms. Farmers expressed interest in learning more about the important role of beneficial invertebrates in controlling pest species in pasture landscapes; and the related role of restored native vegetation in supporting the abundance and diversity of beneficial invertebrates on pasturelands. Farmers who are included in agroecological projects and are presented with the results from these projects could be more open to undertake restoration work on farms.