Functional ecological processes in upland swamps and chain of ponds systems in the Blue Mountains and Southern Highlands of eastern New South Wales, Australia
thesisposted on 2022-03-29, 03:30 authored by Lorraine J. Hardwick
Globally, biodiversity is declining, leading to concerns of permanent loss of ecosystems, central to which is the increasing strength of evidence for the inextricable linkage between biodiversity and ecosystem function. There is an urgent research need to identify the crucial relationships between biodiversity and the functions they require and provide. Many Australian aquatic ecosystems are still poorly studied, including remote and atypical streams, rare and groundwater ecosystems. Furthermore, even in systems where biodiversity is known, ecological functions have rarely been examined. By investigating functional attributes alongside biodiversity measures it was possible, through a sequence of studies to more fully understand dynamics of two rare and at-risk wetland systems west of the Sydney Basin in eastern NSW, Australia. The aquatic ecology and function of Blue Mountains upland peat swamps as part of the THPSS (Temperate Highland Peat Swamps on Sandstone) and Mulwaree ‘chain-of-ponds’ are little known. They represent fundamentally different ecosystems, but both face growing anthropogenic pressure. These studies highlighted the importance of including functional indicators into biodiversity studies as a way of gaining better information for restoration and management. The THPSS swamps were porous to pollutants, with groundwater and streams downstream carrying stormwater nutrients. Leaf litter and cotton strip decay rates were very low, invertebrate abundances were low, but urban stormwater increased both. Release of excavated naturally occurring ironstone, combined with nutrients and high groundwater, led to proliferation of iron bacteria, complex redox reactions, anoxia and reduced productivity. The Mulwaree chain-of-ponds are geomorphic anomalies that act as mesotrophic monomictic lakes once disconnected from river flows. The ponds maintain significant aquatic macrophyte biodiversity, which maintains unusual clear water conditions. The majority of macrophytes are perennial rhizomatous species, but some, such as Water Ribbons (Cycnogeton procerum) are at risk due to water borne dispersal. Water ribbons play a pivotal role in maintaining macrophyte dominance and in carbon cycling within the ponds.