Abstract
Abstract. In eastern Australia, the availability of water is critical for the successful rehabilitation of post-mining landscapes and climatic characteristics of this diverse geographical region are closely defined by factors such as erratic rainfall and periods of drought and flooding. Despite this, specific metrics of climate patterning are seldom incorporated into the initial design of current post-mining land rehabilitation strategies. Our study proposes that a few common rainfall parameters can be combined and rated using arbitrary rainfall thresholds to characterise bioregional climate sensitivity relevant to the rehabilitation these landscapes. This approach included assessments of annual rainfall depth, average recurrence interval of prolonged low intensity rainfall, average recurrence intervals of short or prolonged high intensity events, median period without rain (or water-deficit) and standard deviation for this period in order to address climatic factors such as total water availability, seasonality and intensity – which were selected as potential proxies of both short- and long-term biological sensitivity to climate within the context of post-disturbance ecological development and recovery. Following our survey of available climate data, we derived site "climate sensitivity" indexes and compared the performance of 9 ongoing mine sites: Weipa, Mt. Isa and Cloncurry, Eromanga, Kidston, the Bowen Basin (Curragh), Tarong, North Stradbroke Island, and the Newnes Plateau. The sites were then ranked from most-to-least sensitive and compared with natural bioregional patterns of vegetation density using mean NDVI. It was determined that regular rainfall and relatively short periods of water-deficit were key characteristics of sites having less sensitivity to climate – as found among the relatively more temperate inland mining locations. Whereas, high rainfall variability, frequently occurring high intensity events, and (or) prolonged seasonal drought were primary indicators of sites having greater sensitivity to climate – as found among the semi-arid central-inland sites. Overall, the manner in which these climatic factors are identified and ultimately addressed by land managers and rehabilitation practitioners could be a key determinant of achievable success at given locations at the planning stages of rehabilitation design.
Highlights
As elsewhere worldwide, rehabilitation of post-mining sites in the semi-arid and subtropical environments of eastern Australia have a general objective to establish specific types of native vegetation communities as defined in mine closure plans (DEHP, 2012; DRET, 2006; Bell, 2001; Bradshaw, 1997)
A main consideration of our analysis is that the regional intensity, seasonality, and extremity of rainfall should represent a primary determinant of rehabilitation success among post-disturbance landscapes
Based on the common rainfall criteria used here, the strategy of identifying a given site’s characteristic regarding rainfall availability and temporal distribution could be readily applied to other locations which are affected by climate / rainfall extremes and used to guide initial rehabilitation planning while adding no significant additional time or costs to rehabilitation design
Summary
Rehabilitation of post-mining sites in the semi-arid and subtropical environments of eastern Australia have a general objective to establish specific types of native vegetation communities as defined in mine closure plans (DEHP, 2012; DRET, 2006; Bell, 2001; Bradshaw, 1997). Given the size and severity of mining disturbances, these environments often require extensive and costly rehabilitation of fundamental components of landscape complexity (Green and Sadedin, 2005) This typically involves the reconstruction of landform, lithology and soil toward the development of vegetation communities from early-establishment stages to long-term succession – which are all central themes to this special issue on “Ecosystems in transition” by Hüttl, Hinz, Kögel-Knabner, Schulin, Gerwin, and Subke (Eds.). When climate factors are taken into consideration, the selected parameters (e.g., typically surrounding mean annual rainfall) tend to over-simplify any assessment of regional climatic obstacles For these reasons, this analysis seeks to identify some of the climatic boundaries (i.e., primarily relating to rainfall) relevant to rehabilitation development and to determine the relative sensitivity of ongoing mine sites to climate across different geographic locations in eastern Australia. The manner in which these climatic factors are identified and addressed by land managers and rehabilitation practitioners could be a key determinant of achievable success at given locations at the planning stages of rehabilitation design
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