Alligator River Research Articles

Identifying driving hydrogeomorphic factors of coastal wetland downgrading using random forest classification models

Coastal wetlands provide critical ecosystem services but are experiencing disruptions caused by inundation and saltwater intrusion under intensified climate change, sea-level rise, and anthropogenic activities. Recent studies have shown that these disturbances downgraded coastal wetlands mainly through affecting their hydrological processes. However, research on what is the most critical driver for wetland downgrading and how it affects coastal wetlands is still in its infancy. This study examined drivers of three types of wetland downgrading, including woody wetland loss, emergent herbaceous wetland loss, and woody wetlands converting to emergent herbaceous wetlands. By using random forest classification models for the wetland ecosystems in the Alligator River National Wildlife Refuge, North Carolina, USA, during 1995–2019, we determined the relative importance of different hydrogeomorphic processes and the dominant variables in driving the wetland downgrading. Results showed that random forest classification models were accurate (> 97 % overall accuracy) in classifying wetland downgrading. Multiple hydrogeomorphic variables collectively contributed to the coastal wetland downgrading. However, the dominant control factors varied across different types of wetland downgrading. Woody wetlands were most susceptible to saltwater intrusion and were likely to downgrade if the saltwater table was shallower than 0.2 m below the land surface. In contrast, emergent herbaceous wetlands were most vulnerable to inundation and drought. The favorable groundwater table for emergent herbaceous wetlands was between 0.34 m above the land surface and 0.32 m below the land surface, beyond which the emergent herbaceous wetland tended to disappear. For downgraded woody wetlands, their distance to canals/ditches played a crucial role in determining their fates after downgrading. The machine learning approach employed in this study provided critical knowledge about the thresholds of hydrogeomorphic variables for the downgrading of different types of coastal wetlands. Such information can help guide effective and targeted coastal wetland conservation, management, and restoration measures.

Controlling feral ruminants to reduce greenhouse gas emissions: a case study of buffalo in northern Australia

Context The bourgeoning carbon economy is creating novel ways to incentivise conservation management activities that have the co-benefits of reducing greenhouse gas (GHG) emissions and social inequality. Aim To estimate the monetary value of carbon credits that landowners could generate by reducing ecologically destructive feral populations of the Asian water buffalo (Bubalus bubalis) in northern Australia. Methods First, we estimated buffalo enteric emissions based on the population structure of feral buffalo in northern Australia, and discounted the reduction of fire emissions due to the consumption of grassy fuel by feral buffalo. We then predicted the change in buffalo population size across the South Alligator River region of Kakadu National Park under four buffalo management scenarios: (1) no buffalo control; (2) low-intensity buffalo control; (3) moderate-intensity buffalo control; and (4) high-intensity buffalo control. We quantified the reduction of GHG emissions under the three buffalo control scenarios, relative to the scenario of no buffalo control, while discounting the GHG emissions that directly result from buffalo control actions (e.g. helicopter emissions). Key results All three buffalo control scenarios substantially reduced the estimated GHG emissions that would otherwise have been produced. The low-intensity buffalo control scenario was predicted to abate 790 513 t CO2-e over the 20-year simulation, worth USD15 076 085 (or USD753 804 year−1). Our high-intensity buffalo control scenario had the greatest reduction in GHG emissions, with a total net abatement of 913 231 t CO2-e, worth USD17 176 437 (or USD858 822 year−1). Conclusions The potential value of carbon credits generated by controlling feral buffalo populations in northern Australian savannas far exceeds the management costs. Implications The management of feral ruminants could be incentivised by the generation of carbon credits. Such management could simultaneously avoid GHG emissions, generate income for landowners and offer significant ecological benefits.

Detecting Coastal Wetland Degradation by Combining Remote Sensing and Hydrologic Modeling

Sea-level rise and climate change stresses pose increasing threats to coastal wetlands that are vital to wildlife habitats, carbon sequestration, water supply, and other ecosystem services with global significance. However, existing studies are limited in individual sites, and large-scale mapping of coastal wetland degradation patterns over a long period is rare. Our study developed a new framework to detect spatial and temporal patterns of coastal wetland degradation by analyzing fine-scale, long-term remotely sensed Normalized Difference Vegetation Index (NDVI) data. Then, this framework was tested to track the degradation of coastal wetlands at the Alligator River National Wildlife Refuge (ARNWR) in North Carolina, United States, during the period from 1995 to 2019. We identified six types of coastal wetland degradation in the study area. Most of the detected degradation was located within 2 km from the shoreline and occurred in the past five years. Further, we used a state-of-the-art coastal hydrologic model, PIHM-Wetland, to investigate key hydrologic processes/variables that control the coastal wetland degradation. The temporal and spatial distributions of simulated coastal flooding and saltwater intrusion confirmed the location and timing of wetland degradation detected by remote sensing. The combined method also quantified the possible critical thresholds of water tables for wetland degradation. The remote sensing–hydrologic model integrated scheme proposed in this study provides a new tool for detecting and understanding coastal wetland degradation mechanisms. Our study approach can also be extended to other coastal wetland regions to understand how climate change and sea-level rise impact wetland transformations.

A Validated and Accurate Method for Quantifying and Extrapolating Mangrove Above-Ground Biomass Using LiDAR Data

LiDAR data and derived canopy height models can provide useful information about mangrove tree heights that assist with quantifying mangrove above-ground biomass. This study presents a validated method for quantifying mangrove heights using LiDAR data and calibrating this against plot-based estimates of above-ground biomass. This approach was initially validated for the mangroves of Darwin Harbour, in Northern Australia, which are structurally complex and have high species diversity. Established relationships were then extrapolated to the nearby West Alligator River, which provided the opportunity to quantify biomass at a remote location where intensive fieldwork was limited. Relationships between LiDAR-derived mangrove heights and mean tree height per plot were highly robust for Ceriops tagal, Rhizophora stylosa and Sonneratia alba (r2 = 0.84–0.94, RMSE = 0.03–0.91 m; RMSE% = 0.07%–11.27%), and validated well against an independent dataset. Additionally, relationships between the derived canopy height model and field-based estimates of above-ground biomass were also robust and validated (r2 = 0.73–0.90, RMSE = 141.4 kg–1098.58 kg, RMSE% of 22.94–39.31%). Species-specific estimates of tree density per plot were applied in order to align biomass of individual trees with the resolution of the canopy height model. The total above-ground biomass at Darwin Harbour was estimated at 120 t ha−1 and comparisons with prior estimates of mangrove above-ground biomass confirmed the accuracy of this assessment. To establish whether accurate and validated relationships could be extrapolated elsewhere, the established relationships were applied to a LiDAR-derived canopy height model at nearby West Alligator River. Above-ground biomass derived from extrapolated relationships was estimated at 206 t ha−1, which compared well with prior biomass estimates, confirming that this approach can be extrapolated to remote locations, providing the mangrove forests are biogeographically similar. The validated method presented in this study can be used for reporting mangrove carbon storage under national obligations, and is useful for quantifying carbon within various markets.

Critters of the Carolinas: A team of researchers and community scientists use trail cameras to study wildlife

Photo 1. A female American black bear (Ursus americanus) and her three cubs walking along an access road in Alligator River National Wildlife Refuge in Dare County, North Carolina, USA. Photo captured on a trail camera used for surveying endangered red wolves. Photo credit: Wildlands Red Wolf Survey. Photo 2. A large American black bear (Ursus americanus) walking along a natural area in Hyde County, North Carolina, USA. Photograph taken by a trail camera set by a wildlife biologist for the North Carolina's Candid Critters camera trapping project. Photo credit: North Carolina's Candid Critters. Photo 3. A gray fox (Urocyon cinereoargenteus) inspecting a trail camera set by primary school students with the Museum of Life and Science in North Carolina, USA, for the Students Discover North Carolina camera trapping project. Photo credit: Students Discover North Carolina. Photo 4. A coyote (Canis latrans) inspecting a trail camera set by a community science volunteer in Dare County, North Carolina, USA. Trail camera set as part of the North Carolina's Candid Critters citizen science project. Photo credit: North Carolina's Candid Critters. Photo 5. A gobbler (male) wild turkey (Meleagris gallopavo) caught on a trail camera set by a community science volunteer in Needmore Game Land, found in the Blue Ridge Mountains of North Carolina, USA. Trail camera set as part of the North Carolina's Candid Critters citizen science project. Photo credit: North Carolina's Candid Critters. These photographs illustrate the article “Carolina Critters: a collection of camera trap data from wildlife surveys across North Carolina” by M Lasky, A Parsons, S Schuttler, B McShea, G Davis, L Kalies, R Sutherland, SR Clark, G Hess, H Boone, L Gatens, C Olfenbuttel, J Shaw, C Dukes, T Menke, J Matthews, and RW Kays published in Ecology. https://doi.org/10.1002/ecy.3372.

Self-reported and observed behaviors during black bear viewing at Alligator River National Wildlife Refuge

Social norms are commonly used to investigate visitor beliefs about acceptable wildlife encounters in parks and protected areas. However, there is little information detailing if self-reported norms match actual behaviors. This study compared self-reported norms (n = 304) for viewing distances of adult and cub black bears with behavioral observations (n = 355) of actual encounters at Alligator River National Wildlife Refuge, North Carolina, USA. First, we conducted a crossover design to examine the impact of viewing different groupings of bears at varying distances on acceptability beliefs. Our design significantly affected self-reported, minimum acceptable distance thresholds for an adult bear with cubs (Sequence 1 = 40.69 m; Sequence 2 = 48.24 m). Next, we found self-reported thresholds strongly differed from actual behaviors: 45 % of observations documented visitors closer than 40.69 m from bears. These findings illustrate the value of mixed-methods approaches to understand wildlife viewing behaviors and inform management actions.

Interval North

Interval North Dominique Hecq (bio) Beyond simple genetics, we create our fictitious selves, and there are, at most, two possible plots. Here, the path forks in the dry. The land is subjugated to the ominous shadow of Arnhem Land's escarpment, from which tumble creeks that turn into streams, rivers, and cascades. Click for larger view View full resolution The East Alligator River snakes through high spear grass, open eucalypt woodlands, and paperbark forests to the tidal flats, where pandanus palms dig their roots in the mud. A nomination error: there were and are no alligators, only saltwater crocodiles. They cruise alongside our boat or laze around in the sun on mud flats. A car blasts across the bridge that connects Kakadu National Park to Arnhem Land. Flocks of birds wheel, swivel, and twirl into the trees. A kite swoops down for a catch. An eagle claps its wings astride a dead barramundi. Magpie geese fossick for food on the bank of the river. Strychnine and hibiscus trees swoon in the breeze. This is Gaagudju territory—also spelled "Gagadu," "Gaguju," or "Kakadu." This may be confusing, but Aboriginal place names and words have varying pronunciations between family groups and over time. They are recorded with different spellings by different peoples, too. Here, Aboriginal people are called "Bininj" in the north of the park and "Mungguy" in the south. Their clans comprise at least two family groups sharing ownership of an area of land. Our guide points out that clan boundaries are passed from one generation to the next through the father line. There are nineteen clan groups. Before white settlement, twelve languages were alive here. Today only three are spoken: Gundjeihmi, Kunwinjku, and Jawoyn. I am linguistically challenged, struggling at times to catch the sonorities of Aboriginal English. Across the river grows an isolated pocket of monsoon forest. Our guide lowers his voice: it is a women's sacred site. I explain to the child why it's off-limits to men. And to whites. [End Page 351] A cloud blows over the sky. Blows over. Passes over, or under. Like an invisible bridge. All sorts of tensions implicit in the possibility of bridging. We think of bridges as tensile architectonic matrixes. Not this one. It's built on the river's bed. It is made of solid material. There's no underside. No interplay between motion and stillness. You can only go over it. It's a self-serving bridge. A building up, gathering, hoarding bridge once constructed to facilitate the passage and hunting of water buffaloes. A great metaphor for what some people prudishly call the encounter or contact, that is, colonization. The oldest continent. The child's eyes widen as our guide offers a short history of the Kakadu National Park that I translate into broken French for her, into English for you: Pre-Cambrian sandstone and quartzite have lain here for over two thousand million years. Kakadu's youngest bedrock is over one thousand million years old. Aboriginal settlement extends back to over sixty thousand years, I tell the child in the car. For millennia, Indigenous people have harvested food from plants, trees and waterholes of the escarpment, the billabongs and swamps and rivers of the plain. They have taken care of the land by burning grasslands to improve pastures and enable new plants and trees to germinate. A spooky sight from the road confirms this: will-o'-the-wisps scaling eucalypts. So, what of the encounter? The Chinese, Malays, and Portuguese all allege to have been the first non-Aboriginal visitors of Australia's north coast. The first surviving written account comes from the Dutch, to whom the child and I are related by blood. In 1623, Jan Carstenszoon sailed west across the Gulf of Carpentaria to Groote Eylandt. Abel Tasman then explored part of the coast in 1644 and recorded European contact with Aboriginal people. Almost a century later, in 1802 and 1803, Matthew Flinders surveyed the Gulf of Carpentaria. Phillip Parker King, an English navigator, is responsible for the error of nomination. Parker King named the three Alligator Rivers after the large numbers of crocodiles he mistook for alligators. I glean all this...

Gut Microbiomes Differ Among Dietary Types and Stool Consistency in the Captive Red Wolf (Canis rufus).

Captive management of many wildlife species can be challenging, with individuals displaying health disorders that are not generally described in the wild population. Retrospective studies have identified gastrointestinal (GI) diseases, in particular inflammatory bowel disease (IBD), as the second leading cause of captive adult red wolf (Canis rufus) mortality. Recent molecular studies show that imbalanced gut microbial composition is tightly linked to IBD in the domestic dog. The goal of the present study was to address two main questions: (1) how do red wolf gut microbiomes differ between animals with loose stool consistency, indicative of GI issues, and those with normal stool consistency and (2) how does dietary type relate to stool consistency and red wolf gut microbiomes? Fresh fecal samples were collected from 48 captive wolves housed in eight facilities in the United States and from two wild wolves living in Alligator River National Wildlife Refuge, NC, United States. For each individual, the stool consistency was categorized as loose or normal using a standardized protocol and their diet was categorized as either wild, whole meat, a mix of whole meat and kibble or kibble. We characterized gut microbiome structure using 16S rRNA gene amplicon sequencing. We found that red wolves with a loose stool consistency differed in composition than wolves with normal stool consistency, suggesting a link between GI health and microbiome composition. Diet was not related to stool consistency but did significantly impact gut microbiome composition; gut microbiome composition of wolves fed a kibble diet were significantly different than the gut microbiome composition of wolves fed a mixed, whole meat and wild diet. Findings from this study increase the understanding of the interplay between diet and GI health in the red wolf, a critical piece of information needed to maintain a healthy red wolf population ex situ.

Holocene palaeohydrology of the East Alligator River, for application to mine site rehabilitation, Northern Australia

As a contribution to the estimation of extreme floods and rainfall, palaeofloods in the East Alligator River in tropical Australia were examined to derive estimates of palaeodischarges and their frequency. Nine extreme floods have occurred over 8400 years in a non-stationary series, the youngest five of which are stationary, and the youngest three of which occurred during wet periods produced by variations of the Southern Oscillation Index (SOI) modulated by the Pacific Decadal Oscillation (PDO). The magnitudes of these floods are similar, with one possible exception (in 2007 CE). The extreme floods in the region lie close to, or above, the Australian flood envelope curve showing that floods larger than the expected are possible. Their magnitudes also approximate the Probable Maximum Flood (PMF) but with a much higher frequency than expected. The annual exceedance probability (AEP) of the palaeofloods is 0.3%, which may also be the AEP for the rainfall. These results will be used as input to the design of an artificial landform at the Ranger uranium mine, within the East Alligator catchment, that has to last for 10,000 years. The 2007 CE flood was probably the most extreme flood (and associated rainfall) likely to occur in the vicinity of Ranger under the current climate and will occur in the future along with climate change. Because of the uncertainties associated with projections of future extremes the best design rainfall AEP for the Ranger landform is 0.3%.

Use of airborne Lidar to investigate mangrove accommodation space in macrotidal estuaries of northern Australia

Extensive mangroves in the Northern Territory of Australia reflect the large tidal range along that coast. Airborne Lidar enables interpretation of ground elevation along transects through mangroves and across coastal and estuarine plains, supplementing past levelling surveys of elevation range of the principal mangrove taxa. Mangrove distribution in the upper intertidal varies geographically in response to tidal variations. In the well-mapped Darwin and Bynoe Harbours, Sonneratia alba grows at elevations below mean sea level, whereas Rhizophora occupies a prominent zone that is inundated by neap tides. Ceriops is generally found at higher elevations, often showing a canopy height gradation. A number of mangroves, including Avicennia, occur at the upper bound of the mangrove forest adjacent to the hinterland, which occurs at ~2.8 m above Australian Height Datum (AHD) on the open coast and at ~3.6 m AHD, reflecting tidal amplification, in the embayments. Along the less known macrotidal estuaries of the Alligator Rivers, accommodation space and species distribution varies with distance from the open coast. On the coastal plain that has formed along the southern margin of van Diemen Gulf, Lidar reveals that landwardmost mangroves also occur up to an elevation of ~2.8 m AHD. Amplification of tides in the cuspate-meandering middle sections of the South and East Alligator Rivers enables mangroves to occur up to 3.5–3.6 m AHD, in contrast to the less infilled West Alligator River. The Lidar reveals substrate topography and vegetation structure. The Rhizophora zone is particularly distinct and its steeper gradient implies rapid sediment accretion; Rhizophora has played a disproportionately large role in the sequestration of blue carbon. Low-lying parts of these estuarine plains, particularly former channels, are already experiencing tidal creek extension and saline intrusion, and topography of the landscape behind the mangroves will mean many areas will be vulnerable to future salinization in response to rising sea level.

Human responses to the late Holocene freshwater transition on the northern coastal plains of the Alligator Rivers region in western Arnhem Land

Little is known about cultural change on the inlets of the northern subcoastal plains of the Alligator Rivers region during the transition period between sea-level highstand c.8,000 BP and the establishment of freshwater wetlands (c.2,000 BP to present). The research presented here begins to fill this gap by illustrating differences in Indigenous land-use at two sites only a few kilometres apart and both dating to c.1,000 years ago. Located on the lower reaches of the South Alligator River within what is now Kakadu National Park, the earth mound Myaranji 1 and the shell midden Djindibi 1 provide a snapshot of settlement and subsistence strategies practiced on the floodplains in the late Holocene. This paper presents the analyses of the cultural materials recovered from these two open sites, including those of invertebrate and vertebrate faunal remains, shell and stone artefacts, and pigment on artefacts. Interpretation of the data suggests that occupation was relatively short-lived. Differential representation of food resources indicates that each site was occupied in different seasons. Both local manufacture and regional connectivity are suggested by ochre use and stone artefact working. Evidence from other regional sites implies a subsequent focus for settlement to the south and east.

The Edges

My personal introduction to Debbie was through learning about writing: twenty years ago she stood in front of a diverse group of postgrads and read from work in progress. She lyrically described driving across the Alligator River Flood Plain in Kakadu National Park in the late afternoon with an Aboriginal man, who says a version of ‘Hey Debbie, if you look out the window to the east you’ll see a cool thing’. She looks out the window of the Toyota, and the dark edge of Burrungkuy – the Nourlangie Rock escarpment – is lit up with tiny glittering sparkles of light. The man laughingly explains that it is tourists’ camera flashes, as they photograph the sunset from one of the most famous Indigenous rock art galleries in the world.

A review of revegetation at mine sites in the Alligator Rivers Region, Northern Territory, and the development of a state and transition model for ecological restoration at Ranger uranium mine

Abstract Society’s expectations for mining operations are that they are undertaken using the principles of sustainable development. Numerous mines have been ‘rehabilitated’ in past decades without clear closure criteria or regulatory oversight and are characterised by less than desirable environmental outcomes. These sites provide us with information and data (in some instances) to inform future mine site restoration efforts and the sustainable development of mining resources. However, this information and data are often contained in inaccessible grey literature or have been lost over time. We used records and data on revegetation efforts and outcomes at mine sites in and around the Alligator Rivers Region (ARR) of the Northern Territory, Australia, to demonstrate the extent and currency of rehabilitation knowledge. There have been 20 mines in the region since 1950 and we found that these sites are in various deviated ecological states and that data for these mines were generally unavailable or unable to be located. A number of studies have been conducted at the largest operation, Ranger uranium mine, and there is also information from Nabarlek and South Alligator River Valley mines. We furthered the understanding of the system using available information to develop a preliminary state and transition model for eucalypt-dominated ecosystems in the region. The identification of likely desired and undesired ecological states and management requirements developed in this model could be used to actively guide future restoration and research efforts, particularly at Ranger uranium mine. Based on the lessons learned from the mine sites in the ARR, we provide recommendations for monitoring revegetation in the future.

Carbon Chemistry of Intact Versus Chronically Drained Peatlands in the Southeastern USA

AbstractThe Great Dismal Swamp National Wildlife Refuge (GDS) is a large temperate swamp in Virginia/North Carolina, USA with peat soils historically resistant to microbial decomposition. However, this peatland has been subject to ~200 years of disturbance during which extensive drainage, fire suppression, and widespread logging have increased decomposition and dramatically decreased the distribution of Atlantic white cedar (AWC). The purpose of this study was to determine the impact of long‐term drainage and AWC loss on the carbon chemistry of GDS peats. Peat cores were collected from three drained GDS vegetation communities (pocosin, AWC, and red maple‐black gum) and compared to cores collected from an intact, undrained AWC peatland at the Alligator River National Wildlife Refuge (AR) in North Carolina. The AR peats had higher lignin content in the deeper peat intervals, and lignin content and percent organic carbon were largely invariant with depth compared to the GDS peats. The concentrations of syringyl group phenols were greater in the surface layers of GDS peats, likely reflecting the selective removal of AWC and transition from gymnosperms to angiosperms. Acid to aldehyde ratios for vanillyl and syringyl group phenols indicated that the GDS peats were more decomposed, particularly at depth, and that this occurred under aerobic conditions. Moreover, solid‐state 13C NMR confirmed a coincident loss of carbohydrates and increase in recalcitrant by‐products of carbohydrate degradation with depth. These data indicate that long‐term drainage has accelerated the decomposition of peat at the GDS, reducing the capacity and stability of the carbon sink.

Thinking Continental: Writing the Planet One Place at a Time ed. by Tom Lynch et al.

Reviewed by: Thinking Continental: Writing the Planet One Place at a Time ed. by Tom Lynch et al. John Shoptaw Tom Lynch, Susan Naramore Maher, Drucilla Wall, and O. Alan Weltzien, eds., Thinking Continental: Writing the Planet One Place at a Time. Lincoln: U of Nebraska P, 2017. 345 pp. Paper, $29.95. "I see—New Englandly," Emily Dickinson observed, imagining place not as a noun but an adverb, a way of being. The poet also saw Darwinly, saw through the comforts of a planetary Plan: "Four Trees—upon a solitary Acre—/Without Design / Or Order, or Apparent Action—/Maintain—…" The admirable collection Thinking Continental likewise sees place, and places, adverbially and multifocally. It's bracing to open a book and find geologists and geographers alongside poets, and it's a superior entertainment to link essays with other essays and also with poems. O. Alan Weltzien contributes both an essay and a riprap vista poem to the collection. Bernard Quetchenbach articulates the figure of migration, Susan Naramore Maher (among others) narrates it, and the poet Alberto Rios lyrically reconfigures it. Harmon Maher's survey of the geological figure of layering helps us situate Nessa Cronin's project of "deep mapping." (See also the poems that dig or climb down or look up.) In his essay Emilio Cocco asks us to imagine the ocean as more than the absence of landforms, a viewpoint shared-on the North Atlantic's western edge-by Brendan Galvin and missing from the fascinating but more familiar oceanic perspectives of David Lloyd's poem and Drucilla Wall's essay. Especially refreshing to me are the various decenterings of anthropocentric standpoints, the struggles to see not just regionally but as a mare (Gallagher), a whale (Galvin), a crow (Hogan), or even a slug (Johnston). In their introduction, the editors seek to bridge the local (e.g., Wendell Berry) with the global (e.g., Ursula Heise). Amid the quiet [End Page 214] and roaring devastations of climate change, they prudently remark that to respond to the "new abnormal" (Jerry Brown's term) will "require keen insights not only of scientists but of poets, humanists, and social scientists as well" (xv). To the elements of earth and water, I would add air and fire. (I'm writing in the toxic-smoked East Bay with my Camp Fire face mask on my knee.) And to the markers of the past I would add guideposts and warning flashers pointing toward alternative, (un)sustainable futures. A number of these essays and poems take up, or at least acknowledge, the elephant in the room. Rick Van Noy (following the gradations of Yale E360) charts the degrees of human denial in the subsiding banks and joking bars ("laughing it off" being a common way of deflecting environmental concerns) of the Alligator River. Aliki Barnstone in "Strange" misses her cold-snapped butterfly bush and then zooms out to "the climate chaos" of the contorted "Arctic vortex" (316). The choreographed inscriptions of the young pair of performance artists Jess Allen and Brownyn Preece, though stilted on the page (on Vimeo, there the dance is), adds an activist ecopoetics to this collection. But we don't need only ecological essays or poems or performance pieces to show readers how to reach the planet beneath their phones. The disconnect with nature is taken up in Walter Bargen's darkly witty "Killer Butterfly." And a number of nature essays (by Elizabeth Dodd, Brendan Galvin, to name two) and poems (by Michael S. Begnal, Heid Erdrich, Tess Gallagher) make the exploration and inhabitation of undomesticated places seem irresistible. At some points, though, I find the climate reference frame weirdly missing. If Cocco wants us to reimagine borders from an oceanic perspective, he would also have us see the sea as a swelling, acidifying, overheating carbon sink, a vast waste bin for European landforms. When Nancy S. Cook asserts that "ranching in the American West remains a business, a valuable one for the planet" (268), she might mention the extra-large carbon bootprint of cattle ranching or, looking south, might concede that cattle ranching has promoted Amazon deforestation or say something about green(er) ranching. Mt. Rainier's glaciers are melting...

A Seasonally Dynamic Estuarine Ecosystem Provides a Diverse Prey Base for Elasmobranchs

Tropical river and estuarine food webs sustain diverse biodiversity values and are important sources of nutrients and energy for connected aquatic and terrestrial ecosystems. High-order predators, such as euryhaline elasmobranchs, play critical roles in these food webs, but a lack of detailed information on food web structure limits our ability to manage these species within their ecosystems. We analysed stable carbon (δ13C) and nitrogen (δ15N) isotopes (SI) and fatty acid (FA) biochemical tracers from putative prey species in the estuary of the South Alligator River, northern Australia. These were compared with existing data on four species of elasmobranch from the system to examine food web structure and infer dietary linkages over wet and dry seasons along an environmental gradient of sites. Layman’s SI community metrics indicated that upstream food webs had the greatest trophic diversity, and analyses of FAs revealed distinct prey habitat associations that changed seasonally. Mixing models of SI indicated that most Glyphis glyphis and Glyphis garricki had similar freshwater and mid-river diets whilst Carcharhinus leucas and Rhizoprionodon taylori had largely marine signatures. Multivariate analyses of FA revealed some intraspecific differences, although specialisation indices suggested that the four shark species are trophic generalists. Our results show that riverine food webs can display complex spatiotemporal variations in trophic structure and that coastal and euryhaline mobile elasmobranchs forage in a range of coastal and freshwater habitats, demonstrating their influence on these food webs.

Sea-level rise in northern Australia's Kakadu National Park: a survey of floodplain eukaryotes

Forecasted climate-change models predict that much of northern Australia’s coastal habitats will be in retreat because of saltwater intrusion (SWI) from sea-level rise. A region of primary concern is the nutrient-rich and biodiverse floodplains of world heritage-listed Kakadu National Park (KNP). To understand the implications of SWI, we need fundamental baseline information for floodplain biota from the South Alligator River, KNP, northern Australia, and informative data on how increased and prolonged exposure to salt is likely to shape the eukaryotic community. To assist in addressing these key knowledge gaps, we used amplicon sequencing to examine the composition of eukaryotic soil communities from the South Alligator River floodplain, an ecologically important area at the ‘coalface’ of sea-level rise. Samples were obtained from three river zones and three floodplain morphologies, capturing a wide range of habitats and episodic exposures to both saltwater and freshwater. We found that both the floodplain morphology and positioning along the river significantly influenced eukaryotic composition. However, the influence of these variables varied greatly among the floodplain morphologies, with correlative evidence suggesting that both salinity and pH played a dominant role in shaping communities within lower parts of the floodplain, with this being particularly evident in those regions subjected to major tidal influence (estuarine funnel and sinuous, and cuspate).

What was the vegetation in northwest Australia during the Paleogene, 66–23million years ago?

Fossil pollen and spores preserved in drillcore from both the upper South Alligator River (SARV) in the Kakadu National Park, Northern Territory and the North-West Shelf, Western Australia provide the first record of plants and plant communities occupying the coast and adjacent hinterland in north-west Australia during the Paleogene 66 to 23million years ago. The palynologically-dominant woody taxon is Casuarinaceae, a family now comprising four genera of evergreen scleromorphic shrubs and trees native to Australia, New Guinea, South-east Asia and Pacific Islands. Rare taxa include genera now mostly restricted to temperate rainforest in New Guinea, New Caledonia, New Zealand, South-East Asia and/or Tasmania, e.g. Dacrydium, Phyllocladus and the Nothofagus subgenera Brassospora and Fuscospora. These appear to have existed in moist gorges on the Arnhem Land Plateau, Kakadu National Park. No evidence for Laurasian rainforest elements was found. The few taxa that have modern tropical affinities occur in Eocene or older sediments in Australia, e.g. Lygodium, Anacolosa, Elaeagnus, Malpighiaceae and Strasburgeriaceae. We conclude the wind-pollinated Oligocene to possibly Early Miocene vegetation in the upper SARV was Casuarinaceae sclerophyll forest or woodland growing under seasonally dry conditions and related to modern Allocasuarina/Casuarina formations. There are, however, strong floristic links to coastal communities growing under warm to hot, and seasonally to uniformly wet climates in north-west Australia during the Paleocene-Eocene.

Estimation and Uncertainty of Recent Carbon Accumulation and Vertical Accretion in Drained and Undrained Forested Peatlands of the Southeastern USA

AbstractThe purpose of this study was to determine how drainage impacts carbon densities and recent rates (past 50 years) of vertical accretion and carbon accumulation in southeastern forested peatlands. We compared these parameters in drained maple‐gum (MAPL), Atlantic white cedar (CDR), and pocosin (POC) communities in the Great Dismal Swamp National Wildlife Refuge (GDS) of Virginia/North Carolina and in an intact (undrained) CDR swamp in the Alligator River National Wildlife Refuge (AR) of North Carolina. Peat cores were analyzed for bulk density, percent organic carbon, and 137Cs and 210Pb. An uncertainty analysis of both 137Cs and 210Pb approaches was used to constrain error at least partially related to mobility of both radioisotopes. GDS peats had lower porosities (89.6% (SD = 1.71) versus 95.3% (0.18)) and higher carbon densities (0.082 (0.021) versus 0.037 (0.009) g C cm−3) than AR. Vertical accretion rates (0.10–0.56 cm yr−1) were used to estimate a time period of ~84–362 years for reestablishment of peat lost during the 2011 Lateral West fire at the GDS. Carbon accumulation rates ranged from 51 to 389 g C m−2 yr−1 for all sites. In the drained (GDS) versus intact (AR) CDR sites, carbon accumulation rates were similar with 137Cs (87GDS versus 92AR g C m−2 yr−1) and somewhat less at the GDS than AR as determined with 210Pb (111GDS versus 159AR g C m−2 yr−1). Heightened productivity and high polyphenol content of peat may be responsible for similar rates of carbon accumulation in both drained and intact CDR peatlands.

A Lift for Lichens.

The article discusses research which aims to physically relocate entire communities of lichens at the swamp forests of the Alligator River region in North Carolina. It references a study by James Lendemer et al, published in the October 2016 issue of "Biological Conservation." Topics covered include the biodiversity of lichens stretching from southern New Jersey through South Carolina and their study of the ways to transplant lichen communities from imperiled habitat.