Aquatic biodiversity in the Mediterranean climate rivers of southwestern Australia

Southwestern Australia is recognised as a global biodiversity hotspot, characterised by high diversity and endemism of vascular terrestrial plants. However, the significance of its freshwater biodiversity is not well understood. This review provides an updated account of species richness in rivers in the Mediterranean region (med-region) of southwestern Australia. Taxonomic knowledge of many aquatic invertebrate groups in this region has improved significantly in the last two decades as a result of ecological surveys and government funding for taxonomic research. Of the 662 species of plants and animals surveyed, 43% were found to be endemic to the region, yet when taxonomic groups were considered separately, levels of endemism were varied. To date, few aquatic species from the med-region are listed as threatened; however, many more species would be expected to be included if assessed against appropriate criteria. Conservation efforts are focussed on climate change mitigation and managing the impacts of broad scale land clearing for agriculture. Reserve design and location of important nature reserves on the extreme south coast, limits the ability for species’ movement to cooler, wetter regions. This will necessitate supporting restoration which leads to increased resilience in freshwater ecosystems to withstand the combined effects of climate change and land use.     

Climate change, plant migration, and range collapse in a global biodiversity hotspot: the Banksia (Proteaceae) of Western Australia

Climate change has already altered global patterns of biodiversity by modifying the geographic distributions of species. Forecasts based on bioclimatic envelop modeling of distributions of species suggests greater impacts can be expected in the future, but such projections are contingent on assumptions regarding future climate and migration rates of species. Here, we present a first assessment of the potential impact of climate change on a global biodiversity hotspot in southwestern Western Australia. Across three representative scenarios of future climate change, we simulated migration of 100 Banksia (Proteaceae) species at a rate of 5 km decade^?1 and compared projected impacts with those under the commonly applied, but acknowledged as inadequate, assumptions of ‘full‐’ and ‘no‐migration.’ Across all climate × migration scenarios, 66% of species were projected to decline, whereas only 6% were projected to expand or remain stable. Between 5% and 25% of species were projected to suffer range losses of 100% by 2080, depending mainly on climate scenario. Species losses were driven primarily by changes in current precipitation regimes, with the greatest losses of species projected to occur in a transition zone between wet coastal areas and interior arid regions and which is projected to become more arid in the future. Because the ranges of most species tended to collapse in all climate scenarios, we found that climate change impacts to flora of southwestern Western Australia may be large, even under optimistic assumptions regarding migration abilities. Taken together, our results suggest that the future of biodiversity in southwestern Western Australia may lie largely in the degree to which this hotspot experiences increased drought and in the ability of species to tolerate such decreases in precipitation. More broadly, our study is among a growing number of theoretical studies suggesting the impacts of future climate change on global biodiversity may be considerable.     

Incorporating climate change into recovery planning for threatened vertebrate species in southwestern Australia

Recovery plans are the main tool used for restoration of threatened species in Australia, and identification of key threatening processes is an important feature of them. The aim of this study was to identify how climate change can be incorporated into the recovery planning process using a case study of threatened vertebrates in a global biodiversity hotspot, southwestern Australia. Analysis of 79 recovery planning documents for threatened vertebrate species in the region found that prior to the year 2004, climate change was not included as a threatening process. Post 2004, 32 of 54 (59.3%) documents included climate change as a threatening process. Using bioclimatic modelling, 43 of these species were ranked in terms of their potential exposure to climate change, and a gradient of management intervention aimed at mitigating their exposure to climate change was proposed. This intervention gradient ranged from active management actions aimed at species potentially at risk of extinction due to climate change, through to preservation of habitat in species predicted to lose between 0 and 25% of their current population size. It was proposed that as a priority, the recovery documentation of the 20 species predicted to be most at risk and thus needing a high level of management intervention should identify climate change as a key threatening process, and that more comprehensive analyses of climate change vulnerability be undertaken for these species. Such an approach aimed at prioritising climate change mitigation in threatened species would be useful for other regions where it has been predicted that climate change could have a negative impact on biodiversity.     

Carbon sequestration in riparian forests: A global synthesis and meta‐analysis

Restoration of deforested and degraded landscapes is a globally recognized strategy to sequester carbon, improve ecological integrity, conserve biodiversity, and provide additional benefits to human health and well‐being. Investment in riparian forest restoration has received relatively little attention, in part due to their relatively small spatial extent. Yet, riparian forest restoration may be a particularly valuable strategy because riparian forests have the potential for rapid carbon sequestration, are hotspots of biodiversity, and provide numerous valuable ecosystem services. To inform this strategy, we conducted a global synthesis and meta‐analysis to identify general patterns of carbon stock accumulation in riparian forests. We compiled riparian biomass and soil carbon stock data from 117 publications, reports, and unpublished data sets. We then modeled the change in carbon stock as a function of vegetation age, considering effects of climate and whether or not the riparian forest had been actively planted. On average, our models predicted that the establishment of riparian forest will more than triple the baseline, unforested soil carbon stock, and that riparian forests hold on average 68–158 Mg C/ha in biomass at maturity, with the highest values in relatively warm and wet climates. We also found that actively planting riparian forest substantially jump‐starts the biomass carbon accumulation, with initial growth rates more than double those of naturally regenerating riparian forest. Our results demonstrate that carbon sequestration should be considered a strong co‐benefit of riparian restoration, and that increasing the pace and scale of riparian forest restoration may be a valuable investment providing both immediate carbon sequestration value and long‐term ecosystem service returns.     

Habitat restoration will help some functional plant types persist under climate change in fragmented landscapes

In the next century, global climate change is predicted to have large influences on species' distributions. Much of the research in this area has focused on predicting the areas where conditions will be suitable for the species in future, and thus the potential distribution of the species. However, it is equally important to predict the relative abilities of species to migrate into new suitable areas as conditions shift, while accounting for dynamic processes, such as dispersal, maturation, mortality, and reproduction, as well as landscape characteristics, such as level of habitat fragmentation and connectivity. In this study, we developed a spatially explicit individual‐based model that addresses these factors. As a motivating case study, we based aspects of the model on southwest Australia, a global biodiversity hotspot, but stress that the results obtained are generalizable beyond this region. Using the model, we enhanced current understanding of climate change impacts by investigating how and to what extent the functional traits of plant species affect their ability to move with climate change across landscapes with various levels of fragmentation. We also tested the efficacy of strategic restoration, such as planting corridors to increase connectivity among fragments. We found that even if the landscape is fully intact, only an average of 34.2% of all simulated functional groups had a good chance of successfully tracking climate change. However, our study highlights the power of strategic restoration as a tool for increasing species persistence. Corridors linking fragments increased species persistence rates by up to 24%. The lowest persistence rates were found for trees, a functional group with high dispersal but also long generation times. Our results indicate that for trees intervention techniques, such as assisted migration might be required to prevent species losses.     

Turquoise is the new green: Restoring and enhancing riparian function in the Anthropocene

Riparian ecosystems are hotspots for ecological restoration globally because of the disproportionately high value and diversity of the ecological functions and services which they support and their high level of vulnerability to anthropogenic pressures, including climate change. Degraded riparian ecosystems are associated with many serious anthropogenic problems including increased river bank erosion, water quality decline, increased flood risk and biodiversity loss. Conventional approaches to riparian restoration, however, are frequently too narrow in focus – spatially, temporally, ecologically and socially – to adequately or equitably address the goals to which they aspire. Climate change, along with the intensification of other human pressures, means that static, historically oriented restoration objectives focused solely on prior ecological composition and structure are unlikely to be defensible, achievable or appropriate in the Anthropocene. Conversely, open‐ended restoration strategies lacking clear objectives and targets entail substantial risks such as significant biodiversity losses, especially of native species. A functional approach to planning and prioritising riparian restoration interventions offers an intermediate alternative that is still framed by measurable targets but allows for greater consideration of broader temporal, spatial and cultural influences. Here, we provide an overview of major riparian functions across multiple scales and identify key drivers of, and threats to, these. We also discuss practical approaches to restoring and promoting riparian functions and highlight some key concerns for the development of policy and management of robust riparian restoration in the Anthropocene.     

Can biodiversity hotspots protect more than tropical forest plants and vertebrates?

Conservation International's biodiversity hotspots are areas of high vascular plant endemism combined with high levels of habitat destruction and land use change. Although such hotspots have also been shown to be centres for terrestrial vertebrate endemism, much less is known about how well these areas function as hotspots for other less well‐studied groups, including the hyperdiverse arthropods, other invertebrates and fungi. Because there is a close evolutionary and ecological relationship between insects and plants, we suggest that the potential role of plants as umbrella species for herbivorous insects, potentially herbivorous fungi and nematodes, and parasitic insects should be explored. Finally, we reflect on the increasing social, economic, human conflict and governance issues and the impacts of increasing land use change and global climate change that threaten the biodiversity hotspot system.     

Interactive effects of altered rainfall and simulated nitrogen deposition on seedling establishment in a global biodiversity hotspot

Understanding the interactive effects of global change drivers on vegetation is critical for ecosystem management and restoration, particularly in the Mediterranean‐climate biodiversity hotspots of the world. Climate change, habitat loss and nitrogen deposition have been identified as the key threats to biodiversity loss in these regions, yet their combined effects are poorly understood. We measured the interactive effects of rainfall manipulation (reduction, control, addition) and nitrogen deposition (N addition, N 1 P addition, and unfertilised) on the establishment of 19 Banksia‐woodland species planted at three sites in southwestern Australia. Seedling survival and aboveground biomass was increased with water addition but was not affected by rainfall reduction. N addition alone did not impact seedling survival and growth, but interacted with rainfall manipulation and site in unpredictable ways. Treatment effects were context dependent, which we attributed to historic nutrient enrichment and competitive exotic species that prevented seedling establishment. Plant species (n 5 6) varied greatly in their water‐use efficiency and nitrogen‐use efficiency responses to the imposed treatments, which underscores the difficulty of generalising results to larger numbers of species. Despite our finding that rainfall manipulation and nutrient addition have complex, and in some cases antagonistic effects on seedling survival and growth in Banksia woodlands, our results suggest that local context (i.e. invasive species, land‐use history) will have as much influence on seedling establishment as global changes in climate and nitrogen deposition. We call for more field experiments and predictive models to explore further the importance of ecological context in determining the interactive effects of multiple global change drivers on ecosystems. Finally, to realize effective biodiversity conservation, local management interventions that address invasive species and associated habitat degradation will be as critical in the future as they are now.     

Invasion hotspots for non‐native plants in Australia under current and future climates

We apply the concept of biodiversity hotspot analysis (the identification of biogeographical regions of high species diversity) to identify invasion hotspots – areas of potentially suitable climate for multiple non‐native plant species – in Australia under current and future climates. We used the species distribution model Maxent to model climate suitability surfaces for 72 taxa, recognized as ‘Weeds of National Significance’ (WoNS) in Australia, under current and projected climate for 2020 and 2050. Current climate suitability layers were summed across all 72 species, and we observed two regions of high climatic suitability corresponding to the top 25th percentile of combined climatic suitability values across Australia. We defined these as potential invasion hotspots. Areas of climatic suitability equivalent to the hotspot regions were identified in the composite maps for 2020 and 2050, to track spatial changes in the hotspots over the two time steps. Two potential invasion hotspot regions were identified under current and projected climates: the south west corner of Western Australia (SW), and south eastern Australia (SE). Herbarium data confirmed the presence of 73% and 99% of those species predicted to be in each hotspot respectively, suggesting that the SE has greater invasion potential. The area of both hotspots was predicted to retract southward and towards the coast under future climate scenarios, reducing in size by 81% (SW) and 71% (SE) by 2050. This reduction was driven by the dominance of southern temperate invasive plant species in the WoNS list (47 of the 72), of which 44 were predicted to experience reductions in their bioclimatic range by 2050. While climate is likely to become less suitable for the majority of WoNS in the future, potential invasion hotspots based on climate suitability are likely to remain in the far south of eastern Australia, and in the far south west of Western Australia by 2050.     

Riparian Ecosystems in the 21st Century: Hotspots for Climate Change Adaptation?

Riparian ecosystems in the 21st century are likely to play a critical role in determining the vulnerability of natural and human systems to climate change, and in influencing the capacity of these systems to adapt. Some authors have suggested that riparian ecosystems are particularly vulnerable to climate change impacts due to their high levels of exposure and sensitivity to climatic stimuli, and their history of degradation. Others have highlighted the probable resilience of riparian ecosystems to climate change as a result of their evolution under high levels of climatic and environmental variability. We synthesize current knowledge of the vulnerability of riparian ecosystems to climate change by assessing the potential exposure, sensitivity, and adaptive capacity of their key components and processes, as well as ecosystem functions, goods and services, to projected global climatic changes. We review key pathways for ecological and human adaptation for the maintenance, restoration and enhancement of riparian ecosystem functions, goods and services and present emerging principles for planned adaptation. Our synthesis suggests that, in the absence of adaptation, riparian ecosystems are likely to be highly vulnerable to climate change impacts. However, given the critical role of riparian ecosystem functions in landscapes, as well as the strong links between riparian ecosystems and human well-being, considerable means, motives and opportunities for strategically planned adaptation to climate change also exist. The need for planned adaptation of and for riparian ecosystems is likely to be strengthened as the importance of many riparian ecosystem functions, goods and services will grow under a changing climate. Consequently, riparian ecosystems are likely to become adaptation ‘hotspots’ as the century unfolds.     

Upper thermal tolerances of key taxonomic groups of stream invertebrates

Southwestern Australia has already undergone significant climatic warming and drying and water temperatures are increasing particularly in small streams where riparian vegetation has been cleared. The ability to predict how freshwater fauna may respond to these changes requires understanding of their thermal tolerances. A review of relevant literature and laboratory testing of four aquatic species from southwestern Australia were used to compare upper thermal tolerance (UTT) among key taxonomic groups. UTT for selected species determined by LT₅₀ tests were similar to that of species tested elsewhere. Mean UTT, based on relevant literature and LT₅₀ experiments, ranged from 22.3°C for Ephemeroptera to 43.4°C for Coleoptera. Mean UTT for both Coleoptera and Odonata (41.9°C) were significantly higher than those for all the other groups (22.3–31.5°C) with the exception of Planaria. The mean UTT value of 22.3°C for Ephemeroptera was significantly lower than for Decapoda (29.6°C), Trichoptera (30.1°C) and Mollusca (31.5°C). For three insect orders tested, eurytherms had significantly higher UTT values than stenotherms. The variation in UTT among taxa suggests that additional thermal shifts, caused by riparian disturbance and/or climate change, are likely to create novel assemblages due to the replacement of temperature-sensitive taxa by more tolerant taxa. This has implications for the sustainability of regionally important endemic cool water species.     

Are Mediterranean marine threatened species at high risk by climate change?

Rapid anthropogenic climate change is driving threatened biodiversity one step closer to extinction. Effects on native biodiversity are determined by an interplay between species' exposure to climate change and their specific ecological and life-history characteristics that render them even more susceptible. Impacts on biodiversity have already been reported, however, a systematic risk evaluation of threatened marine populations is lacking. Here, we employ a trait-based approach to assess the risk of 90 threatened marine Mediterranean species to climate change, combining species' exposure to increased sea temperature and intrinsic vulnerability. One-quarter of the threatened marine biodiversity of the Mediterranean Sea is predicted to be under elevated levels of climate risk, with various traits identified as key vulnerability traits. High-risk taxa including sea turtles, marine mammals, Anthozoa and Chondrichthyes are highlighted. Climate risk, vulnerability and exposure hotspots are distributed along the Western Mediterranean, Alboran, Aegean, and Adriatic Seas. At each Mediterranean marine ecoregion, 21%–31% of their threatened species have high climate risk. All Mediterranean marine protected areas host threatened species with high risk to climate change, with 90% having a minimum of 4 up to 19 species of high climate risk, making the objective of a climate-smart conservation strategy a crucial task for immediate planning and action. Our findings aspire to offer new insights for systematic, spatially strategic planning and prioritization of vulnerable marine life in the face of accelerating climate change.     

Deep phylogeographic structuring of populations of the trapdoor spider Moggridgea tingle (Migidae) from southwestern Australia: evidence for long-term refugia within refugia

Southwestern Australia has been recognized as a biodiversity hot spot of global significance, and it is particularly well known for its considerable diversity of flowering plant species. Questions of interest are how this region became so diverse and whether its fauna show similar diverse patterns of speciation. Here, we carried out a phylogeographic study of trapdoor spiders (Migidae: Moggridgea), a presumed Gondwanan lineage found in wet forest localities across southwestern Australia. Phylogenetic, molecular clock and population genetic analyses of mitochondrial (mtDNA) COI gene and ITS rRNA (internal transcribed spacer) data revealed considerable phylogeographic structuring of Moggridgea populations, with evidence for long-term (>3 million years) isolation of at least nine populations in different geographic locations, including upland regions of the Stirling and Porongurup Ranges. High levels of mtDNA divergence and no evidence of recent mitochondrial gene flow among valley populations of the Stirling Range suggest that individual valleys have acted as refugia for the spiders throughout the Pleistocene. Our findings support the hypothesis that climate change, particularly the aridification of Australia after the late Miocene, and the topography of the landscape, which allowed persistence of moist habitats, have been major drivers of speciation in southwestern Australia.     

Impact of Plio-Pleistocene arid cycling on the population history of a southwestern Australian frog

Southwestern Australia is regarded as a global biodiversity hotspot. The region contains a high number of endemic species, ranging from Gondwanan relicts to much more recently evolved plant and animal species. Myobatrachid frogs are diverse in southwestern Australia, and while we know they have speciated in situ in the southwest, we know little about the temporal and geographical patterning of speciation events. Crinia georgiana is an ideal subject to test hypotheses concerning the effect of climatic history on southwestern Australian anurans, as it is an old lineage with a broad distribution covering the entire region. We compiled an extensive phylogeographical data set based on 1085 bp of the mitochondrial gene ND2 for 68 individuals from 18 sites across the species' range. Two major genetic clades were identified which were largely confined to the high rainfall and southeast coastal biogeographical zones, respectively. The clades appear to have diverged around the Plio-Pleistocene border (1.26-1.72 million years ago), concordant with increasing intensity and frequency of arid climate cycles. Subsequent phylogeographical structure appears to have developed primarily during the Pleistocene climatic fluctuations that also have been integral in generating species diversity in the endemic southwestern Australian flora. Phylogeographical analyses identified several dispersal routes, possible refugial areas within the range of the species and also regions of secondary contact. Dispersal routes identified may now be closed to the species because of habitat destruction and salinity problems in inland regions, posing concerns about the evolutionary potential of the species in light of predicted climate change.     

Land‐use and climate change effects on population size and extinction risk of Andean plants

Andean plant species are predicted to shift their distributions, or ‘migrate,’ upslope in response to future warming. The impacts of these shifts on species' population sizes and their abilities to persist in the face of climate change will depend on many factors including the distribution of individuals within species' ranges, the ability of species to migrate and remain at equilibrium with climate, and patterns of human land‐use. Human land‐use may be especially important in the Andes where anthropogenic activities above tree line may create a hard barrier to upward migrations, imperiling high‐elevation Andean biodiversity. In order to better understand how climate change may impact the Andean biodiversity hotspot, we predict the distributional responses of hundreds of plant species to changes in temperature incorporating population density distributions, migration rates, and patterns of human land‐use. We show that plant species from high Andean forests may increase their population sizes if able to migrate onto the expansive land areas above current tree line. However, if the pace of climate change exceeds species' abilities to migrate, all species will experience large population losses and consequently may face high risk of extinction. Using intermediate migration rates consistent with those observed for the region, most species are still predicted to experience population declines. Under a business‐as‐usual land‐use scenario, we find that all species will experience large population losses regardless of migration rate. The effect of human land‐use is most pronounced for high‐elevation species that switch from predicted increases in population sizes to predicted decreases. The overriding influence of land‐use on the predicted responses of Andean species to climate change can be viewed as encouraging since there is still time to initiate conservation programs that limit disturbances and/or facilitate the upward migration and persistence of Andean plant species.     

Old‐growth forests,carbon and climate change: Functions and management for tall open‐forests in two hotspots of temperate Australia

Abstract

The prognosis and utility under climate change are presented for two old‐growth, temperate forests in Australia, from ecological and carbon accounting perspectives. The tall open‐forests (TOFs) of south‐western Australia (SWA) are within Australia’s global biodiversity hotspot. The forest management and timber usage from the carbon‐dense old‐growth TOFs of Tasmania (TAS) have a high carbon efflux, rendering it a carbon hotspot. Under climate change the warmer, dryer climate in both areas will decrease carbon stocks directly; and indirectly through changes towards dryer forest types and through positive feedback. Near 2100, climate change will decrease soil organic carbon (SOC) significantly, e.g. by ～30% for SWA and at least 2% for TAS. The emissions from the next 20 years of logging old‐growth TOF in TAS, and conversion to harvesting cycles, will conservatively reach 66(±33) Mt‐CO₂‐equivalents in the long‐term – bolstering greenhouse gas emissions. Similar emissions will arise from rainforest SOC in TAS due to climate change. Careful management of old‐growth TOFs in these two hotspots, to help reduce carbon emissions and change in biodiversity, entails adopting approaches to forest, wood product and fire management which conserve old‐growth characteristics in forest stands. Plantation forestry on long‐cleared land and well‐targeted prescribed burning supplement effective carbon management.

Abbreviations: C, carbon; CBS, clearfell, burn and sow; CO₂‐e, CO₂ equivalents; CWD, coarse woody debris; DOC, dissolved organic carbon; GHG, greenhouse gas; Mt, megatonnes; SOC, soil organic carbon; SWA, south‐western Australia; SWAFR, Southwest Australian Floristic Region; TAS, Tasmania; TOF, tall open‐forest; t‐C ha^?1 yr^?1, tonnes of carbon per hectare per year     

Forecasted coral reef decline in marine biodiversity hotspots under climate change

Coral bleaching events threaten coral reef habitats globally and cause severe declines of local biodiversity and productivity. Related to high sea surface temperatures (SST), bleaching events are expected to increase as a consequence of future global warming. However, response to climate change is still uncertain as future low‐latitude climatic conditions have no present‐day analogue. Sea surface temperatures during the Eocene epoch were warmer than forecasted changes for the coming century, and distributions of corals during the Eocene may help to inform models forecasting the future of coral reefs. We coupled contemporary and Eocene coral occurrences with information on their respective climatic conditions to model the thermal niche of coral reefs and its potential response to projected climate change. We found that under the RCP8.5 climate change scenario, the global suitability for coral reefs may increase up to 16% by 2100, mostly due to improved suitability of higher latitudes. In contrast, in its current range, coral reef suitability may decrease up to 46% by 2100. Reduction in thermal suitability will be most severe in biodiversity hotspots, especially in the Indo‐Australian Archipelago. Our results suggest that many contemporary hotspots for coral reefs, including those that have been refugia in the past, spatially mismatch with future suitable areas for coral reefs posing challenges to conservation actions under climate change.     

Next-Generation Invaders? Hotspots for Naturalised Sleeper Weeds in Australia under Future Climates

Naturalised, but not yet invasive plants, pose a nascent threat to biodiversity. As climate regimes continue to change, it is likely that a new suite of invaders will emerge from the established pool of naturalised plants. Pre-emptive management of locations that may be most suitable for a large number of potentially invasive plants will help to target monitoring, and is vital for effective control. We used species distribution models (SDM) and invasion-hotspot analysis to determine where in Australia suitable habitat may occur for 292 naturalised plants. SDMs were built in MaxEnt using both climate and soil variables for current baseline conditions. Modelled relationships were projected onto two Representative Concentration Pathways for future climates (RCP 4.5 and 8.5), based on seven global climate models, for two time periods (2035, 2065). Model outputs for each of the 292 species were then aggregated into single ‘hotspot’ maps at two scales: continental, and for each of Australia’s 37 ecoregions. Across Australia, areas in the south-east and south-west corners of the continent were identified as potential hotspots for naturalised plants under current and future climates. These regions provided suitable habitat for 288 and 239 species respectively under baseline climates. The areal extent of the continental hotspot was projected to decrease by 8.8% under climates for 2035, and by a further 5.2% by 2065. A similar pattern of hotspot contraction under future climates was seen for the majority of ecoregions examined. However, two ecoregions - Tasmanian temperate forests and Australian Alps montane grasslands - showed increases in the areal extent of hotspots of >45% under climate scenarios for 2065. The alpine ecoregion also had an increase in the number of naturalised plant species with abiotically suitable habitat under future climate scenarios, indicating that this area may be particularly vulnerable to future incursions by naturalised plants.     

In‐stream habitat and macroinvertebrate responses to riparian corridor length in rangeland streams

Conservation and restoration of riparian vegetation in agricultural landscapes has had mixed success at protecting in‐stream habitat, potentially due to the mismatch between watershed‐scale impacts and reach‐scale restoration. Prioritizing contiguous placement of small‐scale restoration interventions may effectively create larger‐scale restoration projects and improve ecological outcomes. We performed a multi‐site field study to evaluate whether greater linear length of narrow riparian tree corridors resulted in measurable benefits to in‐stream condition. We collected data at 41 sites with varying upstream tree cover nested within 13 groups in rangeland streams in coastal northern California, United States. We evaluated the effect of riparian tree corridor length on benthic macroinvertebrate communities, as well as food resources, water temperature, and substrate size. Sites with longer riparian corridors had higher percentages of invertebrates sensitive to disturbance (including clingers and EPT taxa) as well as lower water temperatures and less fine sediment, two of the most important aquatic stressors. Despite marked improvement, we found no evidence that macroinvertebrate communities fully recovered, suggesting that land use continued to constrain conditions. The restoration of long riparian corridors may be an economically viable and rapidly implementable technique to improve habitat, control sediment, and counter increasing water temperatures expected with climate change within the context of ongoing land use.     

Application of a Gondwanan perspective to restore ecological integrity in the south‐western Australian global biodiversity hotspot

Bounded by ocean and desert, the isolated, predominately Mediterranean‐climate region of south‐western Australia (SWA) includes nine bioregions (circa 44 million hectares). The ecological integrity of the landscapes in this global biodiversity hotspot has been compromised by deforestation, fragmentation, exploitation, and introduced biota. Nature and degree of transformation varies between four interconnected landscapes (Swan Coastal Plain; South‐west Forests; Wandoo Woodlands; and Great Western Woodlands). A Gondwanan perspective emphasizes a venerable biota and a cultural component to deep time. The particular importance of remnants and protected areas is recognized in restoring ecological integrity to Gondwanan landscapes. The nature and magnitude of the restoration task in these ancient, and neighboring, landscapes require higher levels of investment and more time than do recent landscapes. The protection, conservation, restoration, and rehabilitation of ecological integrity require multiple approaches in each landscape as well as consideration of the whole. Active conservation of biota and minimizing the impact of industrial‐ and agricultural‐use are priorities. Integrating a climate focus and rethinking fire are critical restoration considerations to future trajectories under anthropogenic climate change. A legislative mandate to coordinate industrial‐scale restoration and active conservation to build from protected areas must become a societal priority to restore ecological integrity.