Restoring Flood Resilience in Rivers of the Derwent Valley, Tasmania by Josie Kelman, Eve Lazarus and Magali Wright

The aim of our grass roots community group is to help improve agricultural productivity whilst restoring landscapes. One of our key focuses is restoring waterway health to improve resilience, as rivers are the arteries of our landscape, both in an ecological and social sense. By channeling the essential resource of water, they are pathways through the landscape where biodiversity, productivity and human infrastructure are concentrated. Working on rivers is challenging, they are dynamic, changing systems and with the frequency of extreme flood events predicted to increase, this change is magnified. Our rivers are further complicated by the human overlay of water use, static infrastructure and the complex Tasmanian riparian tenure arrangements (a 1 km stretch of riverbank can have multiple public and private owners). The Derwent Catchment Project are working with river users and riparian land managers on a range of river systems to stabilise riverbanks through the removal of willows, revegetation with native riparian species and other bank stabilisation works. In this Tasmanian context we combine practical, pragmatic solutions and meaningful community engagement to achieve restoration goals. We will discuss how our approach differs with the waterway type and condition, social context and flood history. We will also discuss our partnerships and creative approach to attracting resources for river restoration.

Non-native grasses threaten Australia’s important and unique grasslands. Australia’s low resource grasslands are an unlikely home for non-native grasses that have not evolved within these ecosystems and the mechanisms explaining this invasion remain equivocal. Aboveground functional traits of these non-native grasses tend to fall on the resource acquisition specialist end of the spectrum compared to the native resource conservation specialists. The importance of root systems in trait-based research has recently been identified; however, few studies have concentrated on belowground traits across multiple native and non-native Australian grasses. We quantified a suite of above- and belowground traits among four congener pairs of native and non-native Australian grasses and found that some, but not all, expected acquisition specialist traits correlated with the non-native grass species.

While functional traits provide a surrogate measure of function, in order to confirm the hypothesis that non-native grasses have greater nitrogen uptake abilities, we took a further step towards measuring function using microdialysis to sample the soil nitrogen availability experimentally across all eight species in real time throughout their early stages of growth. We found that the natives and non-natives differ in their ability to absorb the available nitrogen. The patterns found across congener pairs in the functional trait study were congruent with those of the microdialysis study. This study provides foundational knowledge regarding the life-history strategies of native and non-native grasses, which will be critical for devising effective management strategies that favour native species in Australia’s economically and ecologically valuable grasslands.

Climate change is predicted to impact mountain vegetation, causing upward shifts in the altitudinal distributions of plant species and communities. Though the effects of climate change have been studied on mountains in Europe and North America, there has been little research in the southern hemisphere. This research examines changes in the vegetation of the Mt. Field Plateau, Tasmania, an ideal location for this study because there have been minimal impacts from changes in land use, invasive plant species or air pollution and no major disturbance events within the area over the past 40 years. A network of 234 vegetation plots (100-m2) initially surveyed in the summers of 1980-1982 were resampled in February-May 2019. The plots span an altitude range of 900 to 1370 m. Ordination of the combined data found two major dimensions of community variation, correlated with altitude (r=0.88, P<0.0001) and drainage (r=0.84, P<0.0001). A fitted vector for year within plot (r=0.39, P<0.0001) was at an angle of 175° to the altitude vector, indicating that, on average, changes in community composition have been towards lower altitude communities. The mean altitude shift was calculated as 19.4 m, with a 95% confidence interval of -25.9 m to -12.9 m, consistent with the early stages of a community response to a warming climate. Future work will fit models of the probability of presence and mean cover of species against altitude and test for upward shifts in responses.

A common goal of ecosystem restoration is to re-establish environments similar to those occurring before disturbance: however, what constitutes ‘similar’ remains an ongoing challenge, especially for faunal communities. A major rehabilitation program is underway at Ranger Uranium Mine in the Northern Territory, aiming “to establish an environment similar to the adjacent areas of Kakadu National Park”. Here we describe recommended standards for the successful achievement of similar faunal assemblages at Ranger. These standards specify: (1) vertebrate and invertebrate taxa to be targeted for assessment; (2) attributes of these taxa for measurement; (3) appropriate reference conditions for benchmarking similarity; (4) acceptable similarity with reference conditions; and (5) robust sampling methodology, given that animal species often have low detectability. Our standards are based on a Western concept of biodiversity, and it is possible that culturally important animal species should be additionally included. Our recommended standards relate to an acceptable end point of rehabilitation. Knowledge of faunal successional trajectories through to acceptable rehabilitation is too limited for reliable trajectory-based predictions, and so acceptable rehabilitation will need to be empirically demonstrated. Whereas the details of our recommended standards apply specifically to Ranger, our approach is applicable to assessment of faunal restoration more generally.

Trees are an important component of many ecosystems as well as ecological restoration of degraded habitat. Understanding the capacity for trees to respond to climate change will help identify priority areas for conservation management and guide seed sourcing for ecological restoration. Whilst phenotypic and genotypic approaches are commonly used to investigate climate adaptation in trees, few studies employ both approaches. Here, we present results using a combined analysis approach of phenotype (quantitative genetic analysis), genotype (SNP-trait associations), and climate associations to investigate climate adaptation and its genetic basis in Eucalyptus microcarpa, an important tree for ecological restoration in south-eastern Australia. Phenotypic data from a 26-year-old provenance trial demonstrated significant genetic variation in growth and leaf traits at both the family and provenance levels. Variation in growth traits was associated with temperature only – mean annual and warmest period maximum, whilst leaf trait variation was found to be associated with a number of temperature, precipitation and aridity related variables. Genotyping of 40 putatively adaptive single nucleotide polymorphisms (SNPs), from previous genomic analyses, identified 13 SNPs associated with growth and leaf traits. Finally, drawing on previous SNP-climate analyses results, several associations were identified across all three comparisons of phenotype, genotype and climate. Though modest in sample size, the application of multiple and independent analyses provide strong support for climate adaptation in E. microcarpa. We discuss the merits of this approach for investigating climate adaptation and the implications of these results for conservation and restoration of E. microcarpa under climate change.

This project was initiated in 2008. At that time, the carbon market had been gaining momentum and there was excitement among conservationists that large-scale tree planting for carbon may result in ecologically meaningful biodiversity outcomes. Greater biodiversity outcomes were expected for carbon projects planted with multiple woody species than for monocultures. However, the assumption prevalent in the industry was that monoculture plantings sequestered more carbon than diverse carbon plantings. So, we designed a field experiment to test this assumption for yate woodland restoration. We planted five replicates of eight treatments that varied according to richness of native woody trees and shrubs from zero to five. Ten years later, we measured growth of trees and shrubs, harvested leaf litter to estimate biomass and sampled soils. We found more biomass in plots of yate and other eucalypts than for plots planted with yate only, or yate planted with different mixes of woody proteaceous, myrtaceous and leguminous shrubs, and native grasses. Unplanted control plots had not been recruited by woody species ten years on. Leaf litter biomass followed similar trends to the live woody biomass. For soils, we found organic carbon decreased with restoration age, and there was a measurable effect of legumes on soil nitrogen. There was a legacy of P-fertiliser at planting that had diminished by 2019. We found no evidence of a carbon biodiversity trade-off in yate woodland restoration at ten years and some evidence of repaired soil processes. This finding has important implications for the emerging carbon market.

The resilience and long-term sustainability of restored plant communities rely heavily on the quality of material used in ecological restoration projects. The toolkit for restoration practitioners now includes projects such as Restore and Renew (Royal Botanic Garden Sydney) that provides practical guidelines for provenance and future climate-based restoration based on ecological and genetic research data. Seed collecting is the main source of material used in restoration and guidelines recommend collections that are genetically diverse and fit. However, whether seed collecting captures the genetic diversity of the source populations remains largely unknown. We present results from a large-scale ongoing project in which we aim to provide empirical data to address this knowledge gap. We will present results from germination experiments assessing seed viability and germination rate (fitness) of multiple plant species each from multiple sites where maternal origin of each seed were recorded. Offspring and mother tissues were genotyped. We address the following questions: how do we capture the genetic diversity of the source population with seed collections and how does mating system affect the level of genetic diversity captured through seed collecting? Preliminary results indicate that seed collections do not always capture the diversity of the parent populations and this varies across populations and species. Fitness as measured through germination rate varies across individuals and populations. Tracking the maternal origin of seeds highlighted how seed from individual mothers can greatly affect fitness outcomes of experiments and assumed diversity of restoration material, something largely overlooked with pooled experimental designs.

Humpback whales use non-song ‘social sounds’ for both within-group and between-group communication. While sounds have been well described, little is known about the function of specific sound types and the potential information encoded within them. As with other species, this information may include static cues related to sex and size, or dynamic cues related to motivational state and arousal level. This study focussed on calls used by humpback whales in competitive groups, where males compete with each other for access to a female during the breeding season. The range of arousal levels and the variety of behaviours observed in these groups provides an opportunity to study how group behaviour and social composition are correlated with sound production and use, and to determine if and how dynamic information is encoded. Data on competitive groups were collected on the Great Barrier Reef, a breeding ground for the east Australian humpback whale population. This included information on group structure, behaviour, intensity of interactions, and acoustic recordings. As expected, the number of call types used, the rate of call production per whale, and the duration of calls increased significantly with arousal level, consistent with other species. However, humpback whales, unlike many other species, may rely more on increasing their call repertoire (number of call types) than changing the features of specific calls to convey information. These results begin to explain why this species possesses such a large diversity of call types and provide evidence for complex communication not found in other baleen whale species.