Changes over time and changes yet to come

Abstract

Change over time is of primary interest for ecologists and managers. Change can be positive and is often part of nature's flux, but it can also be negative if arising from impacts that push ecosystems beyond net sustainability. Researchers work long and hard to develop methodologies to gain insight into how much change is part of acceptable flux and how much is unacceptable impact; and monitoring change is also essential to identify levels of recovery over time after restorative management interventions and, in many cases, to fully test hypotheses. This issue's interview with Mike Dodkin, retired naturalist ranger and pest species officer, touches on all these themes as he recollects projects over a 40-year period. Mike was there during the period of social change that saw mineral sand mining on Australia's east coast sites destined for dedication as national parks post-mining. His role not only included finding ways to reduce mining impacts and attain recovery, but also involved starting up new restoration projects to overcome damage that occurred many decades previously – all such projects which will take many decades hence to be fully realized. In a similar vein in this issue, Brad Farmilio and colleagues report about changes in plant composition after 10 years of monitoring in grazed native pastures in south-eastern Australia after an incentive scheme to reduce impacts on grassland remnants; Richard van Dongen and colleagues observe changes in native vegetation on Dirk Hartog Island, Western Australia many years after removal of non-native herbivores; and, Andrew Carter and Laura Ruykys document a gradual eradication of introduced predators in a fenced reserve in South Australia The passage of time is also important to fully test new hypotheses. Hannah Franklin and colleagues in New Zealand tested the capacity of a range of native riparian plants to take up nitrogen and propose a framework for selecting species that can best buffer farm runoff into streams. Longer term study of riparian plantings based on this model will provide valuable insights, as will application of the value-based arguments for seascape repair put forward by Vishnu Prahalad and colleagues in this issue's second feature and Linda Luck and colleagues’ longer term testing of residual herbicides to reduce Gamba Grass populations in northern Australia. Indeed, all our interventions to improve the functionality of impaired ecosystems could be considered tests of hypotheses, including the core hypothesis that interventions can make a positive difference. Ian McLeod and colleagues acted on an informed hunch in North Queensland that relocation of coral colonies displaced by a cyclone would result in recovery, and all the indicators are pointing to success in this case and many others. In this and many cases involving lower-to-establish species or processes, only time and ongoing monitoring will tell. For example, longer time frames have proven to be useful in the detection by Tai White-Tony and colleagues of long-term patterns of establishment of tree species after mine site restoration in the Jarrah Forest in Western Australia – as well as to allow Kimberly McCallum and colleagues to assess the relationship between the configuration of planted species and their effective pollination in South Australian revegetation sites, many years after plant establishment. With the passage of time also comes change in personnel, such that longitudinal studies and ongoing nurturing of long-term recovery require commitments by institutions that persist beyond the working lives of individuals. It is hard to overstate the need for future managers and researchers to recognize the amount of past work that has gone into many studies and into securing the current condition of many sites. We need to firmly but gently remind current and future generations that long-term effort in these areas is a multi-generational compact.