Of mistletoe and mechanisms'drivers of declining biodiversity in remnant woodlands.

Mistletoe is a prominent component of woodlands throughout south-eastern Australia. Unlike many woodland plants and animals that are becoming increasingly scarce, mistletoe has responded positively to habitat fragmentation and has become more abundant in many areas. These parasitic plants are widely regarded as introduced pests that kill trees and degrade the landscape, yet our research is revealing quite a different story. All mistletoes in Australia are native and they engage in a range of interactions with many animals, having a positive influence on overall biodiversity. Yet, in high densities mistletoes can be detrimental to individual trees and, in extremely high densities, they can contribute to premature tree mortality. Accordingly, we need to understand better the role of mistletoe in remnant woodlands and determine mistletoe densities that achieve these biodiversity benefits without compromising the long-term viability of tree populations. To address this issue, we are conducting a large-scale investigation in the upper Billabong Creek catchment near Holbrook, NSW known as the RIFLE study (Resources in Fragmented Landscapes Experiment). Forty grassy box woodland remnants occurring on private land were selected and surveyed for all terrestrial vertebrates over 12 months. All mistletoes were then removed from twenty of the remnants, leaving the other twenty as controls. Over the next two decades, biodiversity will be compared in these two groups of fragments, with birds, mammals, reptiles and butterflies monitored seasonally and related to a range of resources. Preliminary data indicate that mistletoe provides critical nutritional and nesting resources for many animals, determining distributions for many species and potentially offsetting many of the deleterious consequences of habitat fragmentation. Mistletoe also plays a key role in nutrient dynamics, affecting litter and soil composition which may modify stand-level productivity and successionprocesses. Rather than a threatening process or a weed that should be controlled, mistletoe appears to be crucial to the ongoing maintenance and conservation of our threatened woodlands. While our research is focused on mistletoe in remnant woodlands, the implications of our work extend much further. Our long term aim is to inform restoration and rehabilitation efforts, augmenting existing practices and giving resource managers the process-based knowledge required to implement on-ground works designed for maximum ecological benefit.