The impacts of environmental change on dispersal of large-seeded forest species by the emu

摘要: Seed dispersal is a critical stage in the life-cycle of plants. It process by which seeds escape potentially deleterious density-dependent effects deposition beneath conspecifics and other individuals. Long distance (LDD) – movement considerable distances away from parent plant strongly influences population structures dynamics. In response to global environmental change, LDD key mechanism species may be able establish new habitats climatic ranges. The emu (Dromaius novaehollandiae) an important vector Australian ecosystems, capable traversing many kilometres over few days, retaining large amounts seed within gut for up weeks. this thesis, dynamics four large-seeded jarrah (Eucalyptus marginata) forests southwestern Australia was investigated areas contrasting high/low abundance. The focal could all dispersed represented different life histories; Leucopogon nutans (Ericaceae), fire-killed, short-lived seeder shrub, Persoonia elliptica (Proteaceae), epicormic resprouting tree, Macrozamia riedlei (Zamiaceae), long-lived, apical cycad, Podocarpus drouynianus (Podocarpaceae), basal coniferous shrub. Plant demographic assessment revealed that there no difference structure, rates or spatial structure any sites A simulation model Bayesian change point analysis highlighted difficulties detecting following agent loss. For three larger species, extreme longevity heterogeneity make it difficult detect pattern shorter-lived L. nutans, high production low frequency removal masks effect whether emus are present not terms structure. Visitation fruit were generally each irrespective community depauperate, with only vertebrates acting as local agents species. observed ingest except P. elliptica. Telemetric tagging M. Raven (Corvus coronoides) acts novel vector, regularly dispersing individual > 300 m plant. Spatially-explicit modelling movement, informed Global Positioning System (GPS) tracking birds forest showed highly mobile effective disperse 1500 maximum ca. 7000 during 1000-hr simulated period. Modelling also (and subsequent dispersal) sensitive changes landscape configuration composition. Simulated increases habitat fragmentation disconnection substantially reduced collapsed LDD. (in both quantity quality dispersed), yet remains directly persecuted some agricultural areas, faces same pressures loss organisms. has shown remarkable resilience these pressures, provides pathway expand their ranges under change. However, order fulfil function, requires relatively contiguous landscape. Future work should focus on understanding long-term (seasonal) movements provide complete picture how contributes changing