Absence Of Trees Research Articles

Exploring the Temporary Appropriation of Marginal Open Spaces in Urban Residential Neighbourhoods

Open spaces are essential to the liveability of urban residential neighbourhoods. While formal open spaces, including neighbourhood parks, have been extensively studied for their environmental and social values, there is scanty research on marginal open spaces’ potential uses and benefits. By drawing on an empirical study of residential neighbourhoods in a Nigerian urban centre, this study explores the temporary appropriation of marginal open spaces. The study adopts a mixed-method approach using a questionnaire survey, photographic recordings, observations, open space measurements and interviews with local planning authorities. Findings showed that marginal spaces exist in various types and forms, including open areas along neighbourhood streets and stream corridors. The three major types of temporary appropriation in the residential neighbourhoods were “Informal commerce”, “Leisure/social pursuit” and “Sacralisation (religious activity)”. The most critical concerns regarding open space appropriation, measured on a five-point Likert scale, were “Lack of safety”, “Absence of tree cover/shade” and “Stench from uncollected waste”, with scales of 4.92, 4.68 and 4.42, respectively. Information gathered from the local planning authorities also showed that the users violated the planning regulations guiding the marginal spaces. The study concluded that although the temporary use of open spaces in residential neighbourhoods is essential for improving the residents’ livelihoods and socio-cultural lives, the practice is fraught with several challenges. Consequently, practical policy recommendations were proffered to ensure that marginal spaces are produced as desirable areas for everyday life while maintaining hygiene, safety, cleanliness and comfort.

Mycorrhizal fungi-mediated uptake of tree-derived nutrients by crops – the role of tree-maintained versus crop-associated fungal mycelia

Arbuscular mycorrhizal (AM) fungi translocate nutrients within agroforestry systems but the role of common mycorrhizal fungal networks (CMNs) is unclear. We compared AM fungi-mediated nutrient transfer from mango versus faidherbia trees to maize plants to understand how to foster the AM symbiosis for enhanced agroecosystem sustainability. In mesocosms we applied 15N and 33P tracers via tree stem injection or root-free soil labeling compartments to test tree-to-maize versus soil-to-maize nutrient transfer via AM fungi. Maize plants grew in large in-growth cores with intact versus broken mycelia. Soil-to-maize transfer was assessed with and without trees to compare nutrient transfer via tree-maintained AM fungi i.e. CMNs versus maize-associated AM fungi. Tracer application via stem injection neither corroborated nor falsified our hypothesis of tree-to-maize nitrogen and phosphorus transfer. Soil-to-maize nutrient transfer occurred but was not enhanced by the presence of mango or faidherbia trees. Competition with maize plants for nitrogen but not phosphorus was greater with mango than faidherbia trees. Results from our experimental set-up provide neither evidence nor disproval for CMNs between two-year-old trees and ten-week-old maize plants. In the absence of trees and tree-maintained AM fungal mycelia maize plants developed their own AM fungal mycelia that mediated uptake of nutrients from beyond the maize plants’ rooting zones.

Spatial Ecology of an Arboreal Iguana (Oplurus cyclurus) in a Treeless Landscape.

Understanding the spatial ecology of species has important implications for conservation, as it helps identify suitable habitats and minimum requirements for biodiversity monitoring and management. The spiny-tailed lizard Oplurus cyclurus is a widespread endemic iguanid occurring in dry areas of southern and western Madagascar. While the species is known to be mostly arboreal, populations of the Isalo sandstone massif suggest local adaptation to a less forested savannah and a more exposed habitat. We radio-tracked 19 spiny-tailed lizards to investigate the species' rock-dwelling behaviour and spatial ecology at Isalo National Park. Tracked individuals showed high site and burrow fidelity, and a basking behaviour mostly tied to the accessibility of their burrow, the time of day, and their life stage. Activity peaked during the sunniest hours, while juveniles were more active than adults with unfavourable weather conditions. Despite high burrow fidelity, lizards used shelters non-exclusively, regularly changing (approx. once a week) with neighbouring burrows (average distance between burrows = 13.6 m). However, there was no obvious relation between lizards' body and/or tail size and the width and depth of selected burrows. Dynamic Brownian Bridge Movement Models estimated frequented areas over 247.8 m2 (95% isopleth), where territorial overlap is common. Our results challenge the notion that burrow-site fidelity is the sole driving factor behind space utilization in the studied population. We argue that the apparently unusual saxicolous habits imposed by habitat features (the absence of trees) may lead to local behavioural adjustments influencing antipredatory and foraging strategies, as well as intraspecific interactions.

Effect of roadside trees on pedestrians' psychological evaluation of traffic noise.

This study aims to investigate the interplay between roadside trees and pedestrians' assessment of traffic noise and comfort. The study examines the potential effects of visual and design elements of roadside trees on the overall soundscape comfort. The study design involves a systematic exploration of different conditions, encompassing traffic volume, distance from sound source, and tree density. For each combination, two experimental scenarios are created: (1) participants experience a binaural sound recording exclusively, and (2) participants experience the same binaural recording while concurrently immersed in a virtual reality (VR) video. Analysis of participants' noise perception, measured using a quiet-noisy scale, reveals no significant disparity between conditions. This suggests that the mere presence of roadside trees does not necessarily lead to a perceived reduction in noise loudness. However, evaluation of sound intensity exposes a notable discrepancy between low and medium tree density levels. Furthermore, the study confirms the impact of roadside tree visibility, with scenes containing trees yielding more positive evaluations compared to sound-only scenarios. Remarkably, the absence of trees in the roadside scene garners consistent evaluations across both experimental conditions. Significantly, higher roadside tree density in conjunction with the combined sound and VR video condition prompts a more favorable assessment than the sound-only scenario. While the study indicates that roadside trees might not substantially mitigate perceived physical noise levels, their influence on the psychological well-being of urban inhabitants is considerable. The findings highlight that even though these trees may not overtly diminish noise, they hold substantial potential to enhance the overall comfort and well-being of city residents. This underscores the multifaceted benefits of integrating green spaces into urban design for improving the quality of urban soundscapes and residents' experiences.

The marine avifauna of Matthew and Hunter Islands, two remote volcanoes of the New Hebrides chain

The marine avifauna of Matthew and Hunter Islands, two remote volcanoes of the New Hebrides chain Breeding birds recorded on Matthew and Hunter Islands in the tropical southwestern Pacific between 1973 and 2018 are summarised from a compilation of reports, for which various methods were used for counting seabirds. These methods included line transects, or direct observations using telescope or binoculars, or exhaustive counts, depending on the species observed and its nesting habitat. Population size estimates and reproductive periods are given. The total number of seabird species recorded breeding on the two islands was n = 14. This total includes seabird species breeding on both islands (n = 7): black-winged petrel Pterodroma nigripennis, wedge-tailed shearwater Ardenna pacifica, red-tailed tropicbird Phaethon rubricauda, masked booby Sula dactylatra, brown booby S. leucogaster, brown noddy Anous stolidus, and grey noddy A. albivitta. Hunter island also harbours a small colony of Herald petrel Pterodroma heraldica, and colonies of lesser and great frigatebirds (Fregata ariel and F. minor), red-footed booby S. sula and, black noddy A. minutus and white tern Gygis alba. Matthew Island harbours a large colony of sooty tern Onychoprion fuscatus; an undetermined storm petrel may also breed there. Differences between the two islands regarding community composition of seabirds are explained by the absence of trees on Matthew Island and the presence of the Polynesian rat Rattus exulans on Hunter Island. Brown noddies bred exclusively during the austral summer, as did black-winged petrels and wedge-tailed shearwaters, while the Herald petrel and the two frigatebirds seemed to preferentially breed in the winter. The red-tailed tropicbird, the three boobies, the grey noddy and the sooty tern appeared to reproduce year-round. Disturbance caused by human activities was irregular but devastating to seabird colonies. The diversity and abundance of seabird species breeding on these islands makes them regionally important sites for conservation. Key words: Seabird, Population, Reproduction, Threats, Polynesian rat; Helicopters

Contributions of roads to surface temperature: evidence from Southern California

Planners often regard streets as targets for mitigating urban heat across cities by virtue of being abundant, publicly-owned, low-albedo, low-vegetation surfaces. Few studies, however, have assessed the role streets play in contributing to urban heat, and the scale of their effect relative to the built environment around them. We examine the relationship between road area and land surface temperature across a variety of biophysical regions through the urban areas of Los Angeles and San Bernardino Counties in Southern California. Our results show that wide streets have no consistent, detectable effect on urban heat. Rather, vegetation is the primary cooling mechanism for urban areas. In the absence of trees, concrete highways are the coolest surfaces, though particular hot or cool pockets (e.g., airports, industrial centers, parks) can dominate neighborhood temperature signatures. In considering LST mitigation strategies, these hotspots might outweigh the cumulative effects of road surface changes.

Tree damage index in Taman Merdeka, Binjai City, North Sumatra Province

Tree damage is one of the important indicators for tree health monitoring. Data on tree damage conditions will be very useful for city park managers to determine tree care measures. The purpose of this study was to determine the index of tree damage in Taman Merdeka, Binjai City, North Sumatra Province. The assessment of the three parameters (location of damage, type of damage, and level of damage severity) on the tree damage indicators refers to the Forest Health Monitoring method developed by the USDA Forest Service (1997). A total of 86 (eighty six) individual trees from 15 (fifteen) tree species growing in Taman Merdeka – Binjai City were successfully measured for their damage conditions. The results of this study indicate that overall the trees that grow in Taman Merdeka Binjai City are in good condition. This can be seen from the absence of trees that have a heavy damage index. The results of this study showed that as many as 47,67% of tree species growing in Taman Merdeka – Binjai City had a moderate damage index, dan as many as 52,33% had a low damage index. Five species of trees are known to have moderate damage, namely mahoni (Swietenia macrophylla), saga (Adenanthera pavonina), dadap merah (Erythrina christagali), ketapang kencana (Terminalia mantally), and mangga (Mangifera indica).

Flora of the botanical-geographical plot “Steppes of Ukraine” in the M.M. Gryshko National Botanical Garden of the NAS of Ukraine

In 2020–2022, the complete taxonomic composition of the flora for the botanical-geographical plot “Steppes of Ukraine” at the M.M. Gryshko National Botanical Garden of the NAS of Ukraine (NBG) was studied and analyzed. This plot was established at the NBG in 1949 to demonstrate the floristic diversity of the Ukrainian Steppes ex situ. According to the inventory results, 347 species and infraspecific taxa from 196 genera and 53 families of higher vascular plants were recorded in the flora of the plot. The steppic component of this plot joins 213 species and infraspecific taxa (61.38 % of the total number of inventoried taxa) belonging to the collection fund and representing the flora of the Steppes of Ukraine, 126 species and infraspecific taxa (36.31 %) of which are introduced plants and 87 species and infraspecific taxa (25.07 %) are native plants. During the inventory, spontaneously growing plants that are not a part of the collection fund were precisely studied. Among inventoried plants, native non-steppic plants are represented by 46 species and infraspecific taxa (13.26 %); alien plants – by 88 taxa (25.36 %), including ergasiophygophytes (45 taxa, 12.97 %) and xenophytes (43 taxa, 12.39 %). The plants of the collection fund predominate on the plot and form the main vegetation cover.Currently, the taxonomic composition of the plot is similar to the characteristics of regional meadow-steppes. The perennials dominate in the biomorphological structure of the plot’s flora (63.69 %), which is typical for the steppic phytocoenoses. In general, a significant number of trees is present here (5.48 %), which is explained by the forest communities surrounding the plot and, as a result, their active self-sowing. Hemicryptophytes prevail in the plot’s flora (60.52 %). Nevertheless, the collection fund of the plot is distinguished by the absence of trees, a greater number of perennials (79.34 %), and hemicryptophytes (72.77 %). The steppic (33.33 %) and marginal (33.33 %) plants prevail in the collection fund, while the amount of meadow plants (18.78 %) is still significant. In the plot “Steppes of Ukraine”, most of the rare introduced plants formed stable homeostatic introduction coenopopulations. Among them, 15 species and rare infraspecific taxa are listed in the Red Book of Ukraine.

Veteran trees in decline: Stratified national monitoring of oaks in Norway

Old veteran trees function as biodiversity hotspots in both forests and open landscapes, and protecting such trees is an important measure to halt loss of biodiversity. Nevertheless, the number of veteran trees continues to decline worldwide, although estimates of this decline mainly stem from geographically restricted case studies. In Norway, veteran oak trees have received special protection since 2011 through the Norwegian Biodiversity Act, however, there is a lack of knowledge on status and trends for these trees. A national monitoring program was started in 2012, using a random, stratified sampling procedure. We use the data from the baseline survey and the first monitoring revisit to estimate the total number as well as mortality trends of veteran oaks in Norway. Further, we assess recruitment potential (in the baseline survey) and changes in variables describing ecological state such as regrowth.The monitoring area covered the geographical distribution of oaks in Norway and was divided into > 200000 plots of 500 × 500 m. A set of 500 monitoring plots were randomly selected from two strata: High probability plots (n = 100; plots with high probability of occurrence of veteran oaks), and Low probability plots (n = 400), using existing knowledge and databases. Plots were surveyed over a five year-period (2012–2016), with 20 HighProb-plots and 80 LowProb-plots each year. All veteran oaks that were observed during the baseline survey were revisited in 2019, three to seven years after they were initially registered. Tree absence and cause of death/change of ecological status was recorded. We estimated a total of 138100 veteran oaks in Norway based on the baseline survey, of which 25000 could be denoted “top quality oaks”. Based on the revisit, we estimated a loss of 7600 veteran trees, i.e., an annual mortality rate of 1.2%. Recruitment oaks were present in most plots with veteran oaks, but recruitment into the veteran oak category is slow and unlikely to balance out the mortality rate. More precise estimates of recruitment should be prioritized in future monitoring. The estimate of 138000 veteran oaks far exceeds the appr. 10000 trees registered in the national database, and clearly demonstrates the need for continued mapping and monitoring to improve the foundation for a knowledge-based land management. Further, this short-term monitoring demonstrates the decline of this biodiversity hotspot and pivotal source of ecosystem functions, despite increased protection in recent years. Our results and conclusions are relevant also for veteran trees of other species than oak.

The Hill Cumorah: Restoring a Sacred Site

The Hill Cumorah: Restoring a Sacred Site

Aerial surveys reveal biotic drivers of mangrove expansion along a Thai salt flat ecotone

Rapid sea level rise (SLR) could overwhelm the adaptive capacity of many mangrove forests. The conservation of functional mangrove ecosystems will rely on their expansion into upper intertidal areas, including salt marshes and salt flats, in advance of SLR. The development of new mangrove habitats could be accelerated by amplifying positive biotic interactions among herbaceous plants, macrofauna, and mangrove trees, such as trapping of hydrochorous propagules or site amelioration. It was investigated how biotic and abiotic factors influenced the expansion of mixed‐species mangrove stands along a mangrove‐salt flat ecotone. Multi‐temporal unmanned aerial vehicle (UAV) imagery (< 1 cm/pixel) was used to monitor seedlings of Avicennia alba, Bruguiera cylindrica, and Lumnitzera racemosa in three sample plots (0.7–0.9 ha) over 2 years. The aerial images were used to map mangrove crowns, sedges (Fimbristylis tetragona), substrate elevation, and microtopography. The spatial distribution of seedlings was modeled using point pattern processes; mixed‐effects models were used to analyze how environmental factors influenced seedling survival and growth. The spatio‐temporal patterns of mangrove regeneration revealed that sedges and macrofauna facilitated the regeneration of mangroves into higher‐elevated areas of low tree density. Sedges not only trapped seeds but also increased the likelihood of survival among seedlings of all species. Large‐sized propagules established in undulating microtopography created through the bioturbation of macrofauna. Herbaceous vegetation expanded the range of macrofauna in the absence of trees. Thus, the migration of mangroves into hypersaline retreat areas may be accelerated by enhancing the growth of herbaceous vegetation and promoting burrowing macrofauna.

Performance and host association of spotted lanternfly (Lycorma delicatula) among common woody ornamentals

Lycorma delicatula (spotted lanternfly) has a broad host range with a strong preference for the invasive host plant from its native range, tree of heaven (Ailanthus altissima); it had long been speculated that L. delicatula could not develop or reproduce without access to tree of heaven. In 2019, we found that this assumption was incorrect, but fitness was reduced in the absence of A. altissima in that the number of egg masses laid was dramatically fewer for insects reared on suitable non-A. altissima host plants that had recently been established. We hypothesized that longer established, larger trees (of the same species) would improve the fitness of L. delicatula in the absence of tree of heaven. In spring 2020, we examined insect performance with and without access to A. altissima by tracking development, survival, host tree association and oviposition in large enclosures with trees planted two years prior to the study. Each enclosure included one each of Juglans nigra, Salix babylonica and Acer saccharinum along with either one A. altissima or one Betula nigra; these trees had twice the diameter of the same trees the previous year. We reared nymphs with and without access to A. altissima, released them into the corresponding large enclosures as third instars, and monitored them from early July 2020 through November 2020. We also determined whether lack of access to A. altissima by parents of L. delicatula have any fitness effects on offspring performance. To ensure adequate adult populations for comparing fecundity between treatments, third instars were released into the multi-tree enclosures due to high mortality in earlier instars that occurred in a similar study in 2019. Insect survival was higher and development faster with access to A. altissima. Third and fourth instar nymphs were most frequently observed on A. altissima when it was present, while adults were equally associated with A. saccharinum and A. altissima. In the absence of A. altissima, nymphs were most frequently found on S. babylonica, while adults were most often on A. saccharinum. Females with access to A. altissima deposited nearly 7-fold more egg masses than those without access to A. altissima, which is consistent with the difference in egg mass numbers between the two treatments the previous year; thus, our hypothesis was rejected. The offspring of parents that had been reared without access to A. altissima showed similar survival and development time from egg to adult as offspring from parents that never had access to A. altissima. These findings suggest that managers need to be aware that even in the absence of A. altissima in the landscape, several hardwood host trees can be utilized by L. delicatula to develop and reproduce, but fitness without A. altissima is likely to still be reduced.

Геоактивные зоны и структура растительных сообществ в связи с новыми открытиями в космической геологии

The purpose of the work is to find out how plants react to such zones and whether their phytoindication is possible. Two territories of the Perm territory were studied: the Vishersky Nature Reserve and forests near Perm. The research methodology included lineament and geostructurometric analysis of space images and special maps using ring structures discovered on the Earth’s surface by Yu. I. Fivenskii, as well as phyto- and bioindication of small geoactive zones. It was found that in the forests near Perm favorable zones of such zones occupy 1.44% of the territory and within their limits the safety of common pine (Pinus sylvestris L.) is 29–42 times higher. Phytoindication of small geoactive zones of 1.0 and 3.0 m by common pine was shown in the zones of influence of these zones: 0–18 cm — the radius of inhibition with the absence of trees; 19–29 cm — the depression zone with small trees; 30–48 cm — the comfort zone with medium and large trees. Two types of networks formed by zones of 1.0 and 8.0 m in size near Perm (on the plain) and in the reserve (in the mountains) were compared. In the mountains, with high geodynamic activity of territories, the networks are oriented in one direction, while on the plain their orientation is misaligned by 30°. In the reserve, large trees of Siberian spruce (Picea obovata Ledeb.) were located on small geoactive zones of 1.0 and 8.0 m, and trees of Siberian pine (Pinus sibirica Du Tour) — on zones 1.0 and 3.0 m in combination with zones 16, 32 and 55 m. In the subgolets zone, ring structures of perennial plants were also found on the first two types of zones. In addition, along the edges of the swamps, chains of trees were found whose direction coincides with ring faults, and the chains themselves are similar to the structure of small geoactive zones networks, and this fractality requires field verification. The hypothesis recharge of plants within geoactive zones is proposed, which also explains the successful growth of trees on rocks, where the amount of available soil is minimal.

Thermal Environment of Urban Schoolyards: Current and Future Design with Respect to Children’s Thermal Comfort

Urban outdoor thermal conditions, and its impacts on the health and well-being for the city inhabitants have reached increased attention among biometeorological studies during the last two decades. Children are considered more sensitive and vulnerable to hot ambient conditions compared to adults, and are affected strongly by their thermal environment. One of the urban outdoor environments that children spend almost one third of their school time is the schoolyard. The aims of the present manuscript were to review studies conducted worldwide, in order to present the biophysical characteristics of the typical design of the urban schoolyard. This was done to assess, in terms of bioclimatology, the interactions between the thermal environment and the children’s body, to discuss the adverse effects of thermal environment on children, especially the case of heat stress, and to propose measures that could be applied to improve the thermal environment of schoolyards, focusing on vegetation. Human thermal comfort monitoring tools are mainly developed for adults, thus, further research is needed to adapt them to children. The schemes that are usually followed to design urban schoolyards create conditions that favour the exposure of children to excessive heat, inducing high health risks to them. The literature survey showed that typical urban schoolyard design (i.e., dense surface materials, absence of trees) triggered high surface temperatures (that may exceed 58 °C) and increased absorption of radiative heat load (that may exceed 64 °C in terms of Mean Radiant Temperature) during a clear day with intense solar radiation. Furthermore, vegetation cover has a positive impact on schoolyard’s microclimate, by improving thermal comfort and reducing heat stress perception of children. Design options for urban schoolyards and strategies that can mitigate the adverse effects of heat stress are proposed with focus on vegetation cover that affect positively their thermal environment and improve their aesthetic and functionality.

Numerical study on flow field and pollutant dispersion in an ideal street canyon within a real tree model at different wind velocities

Studying the effects of trees on airflow and pollutant dispersion in urban street canyons is of considerable significance to clarify the laws of urban micro-scale airflow and pollutant dispersion. To characterize the trees in street canyons, different from the traditional vegetation resistance source method, in this paper, a fine tree model is used for numerical simulations of the airflow and pollutant dispersion in street canyons at varying inflow wind velocities. It is found during the study that the presence of trees physically blocks the airflow in street canyons. The airflow is sheared by the trunk, canopy, or branches, and then circumvents them, especially at a high inflow wind velocity. The low-velocity area in the street canyon distributes to the leeward side of the tree trunk as well as in the canopy area, and a discrete low-velocity distribution exists mainly in the canopy area. The average wind velocity in a street canyon with trees is approximately 39.5% lower at an inflow wind velocity of 1.7 m/s than that in a canyon without trees. In the presence of trees, the pollutant concentration in street canyons increases significantly, and the pollutants significantly accumulate between the tree trunk and the leeward side. With increasing inflow velocity, the pollutant concentration in a street canyon constantly changes but is much higher than that in the absence of trees. At a wind velocity of 5.7 m/s, the average pollutant concentration is 18.6% higher in street canyons with trees than in those without trees.

Tree Cover in the Surrounding Landscape Reduces Burrowing Owl (Athene cunicularia) Occupancy of Black-Tailed Prairie Dog Colonies in South Dakota

Burrowing Owl (Athene cunicularia) population declines have led to the owl's designation as a species of conservation concern in South Dakota. Burrowing Owls nest primarily in black-tailed prairie dog (Cynomys ludovicianus) colonies, but a significant proportion of colonies in South Dakota are not occupied by owls. We studied the influence of landscape-level habitat variables on colony selection by Burrowing Owls. We used call-playback surveys to document presence or absence of Burrowing Owls at 613 prairie dog colonies throughout western and central South Dakota. We used a geographic information system to calculate the percent cover of prairie dog colonies, grassland, cropland, and tree canopy in the surrounding landscape at four buffer sizes. We modeled Burrowing Owl occupancy of prairie dog colonies using logistic regression, and ranked models using Akaike's Information Criterion. All competitive models contained a tree-canopy-cover variable. Increasing tree canopy cover within 800 m and 1200 m of colony centers was associated with decreasing likelihood of occupancy by Burrowing Owls. Grassland, cropland, and prairie dog colony cover variables did not influence occupancy by Burrowing Owls, and these variables did not improve model fit or discrimination. In landscapes where the presence of nesting burrows is not a limiting factor, as in central and western South Dakota, Burrowing Owls occupied colonies based on the absence of trees. Trees provide habitat for avian and mammalian predators and reduce the available foraging area for Burrowing Owls around prairie dog colonies. Management for Burrowing Owls should include conserving prairie dog colonies in landscapes with few trees and preventing the establishment of trees near occupied colonies.

The Falkland Islands’ palaeoecological response to millennial‐scale climate perturbations during the Pleistocene–Holocene transition: Implications for future vegetation stability in the southern ocean islands

ABSTRACTOceanic island flora is vulnerable to future climate warming, which is likely to promote changes in vegetation composition, and invasion of non‐native species. Sub‐Antarctic islands are predicted to experience rapid warming during the next century; therefore, establishing trajectories of change in vegetation communities is essential for developing conservation strategies to preserve biological diversity. We present a Late‐glacial‐early Holocene (16 500–6450 cal a bp) palaeoecological record from Hooker's Point, Falkland Islands (Islas Malvinas), South Atlantic. This period spans the Pleistocene‐Holocene transition, providing insight into biological responses to abrupt climate change. Pollen and plant macrofossil records appear insensitive to climatic cooling during the Late‐glacial, but undergo rapid turnover in response to regional warming. The absence of trees throughout the Late‐glacial‐early Holocene enables the recognition of far‐travelled pollen from southern South America. The first occurrence of Nothofagus (southern beech) may reflect changes in the strength and/or position of the Southern Westerly Wind Belt during the Late‐glacial period. Peat inception and accumulation at Hooker's Point is likely to be promoted by the recalcitrant litter of wind‐adapted flora. This recalcitrant litter helps to explain widespread peatland development in a comparatively dry environment, and suggests that wind‐adapted peatlands can remain carbon sinks even under low precipitation regimes. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd.

Using a U-net convolutional neural network to map woody vegetation extent from high resolution satellite imagery across Queensland, Australia

Convolutional neural networks offer a new approach to classifying high resolution imagery. We use the U-net neural network architecture to map the presence or absence of trees and large shrubs across the Australian state of Queensland. From a state-wide mosaic of 1 m resolution 3-band Earth-i imagery, a selection of 827 squares (1 km2) are manually labeled for the presence of trees or large shrubs, and these are used to train the neural network. The training is intended to capture the textures which are primary visual cues of such vegetation. The trained neural network has an accuracy on independent data of around 90%. The resulting map over the whole of Queensland (1.73 million km2) is intended to be manually checked, and edited where necessary, to provide a high quality map of woody vegetation extent to serve a range of government policy objectives.

Microscopic use-wear and residue analysis of stone reamers recovered from the early Holocene layer of the Eel Point site (CA-SCLI-43) on San Clemente Island, California

The Eel Point site on San Clemente Island is the earliest occupation known for the southern Channel Islands of California. Excavations in the early Holocene layer yielded stone tools scattered over a 9 m2 area. These tools include drills, reamers, scrapers, abraders, spoke-shave, macroblade plane, burin, wood-splitting wedges and a modified sea mammal rib with asphalt stains. Examination of technological attributes and microscopic use-wear patterns initially concluded the tools were used for wood-working. Further microscopic residue analysis conducted on the twelve reamers identified the remains of woody plant materials, ocher and asphalt. No other residues, including stone, shells or fauna were found. The absence of trees in this location suggests the tools were employed in working on imported wood materials, such as those used in watercraft required to transport people to and from the island. The findings herein support the hypothesis that these specific wood-working stone tools, found in close proximity to each other represent an early Holocene watercraft construction or maintenance tool-kit.

Effects of crab burrows on sediment characteristics in a Ceriops australis-dominated mangrove forest

The presence of mangrove trees and crab burrows potentially contribute to localized variation in sediment elevation and affect sediment characteristics in these ecosystems, but the interacting effects of trees and burrows are largely unknown. Using a field study and artificial burrow experiment, we investigated variation in sediment redox potential, organic matter content, carbon to nitrogen ratios and activities of microbial communities related to presence and absence of trees and burrows. The presence of mangrove trees of the species Ceriops australis decreased the redox potential of the sediment, which may favor organic matter preservation, but no significant differences were observed in percent organic matter in sediment next to trees versus distant from trees. The effects of C. australis on sediment redox conditions were counteracted by the presence of crab burrows in deeper (20 cm) sediments. The utilization of a variety of carbon sources by microbial communities varied between the surface of crab burrow walls and bulk sediment, indicating crab burrow-induced changes in microbial communities, whereas the presence of C. australis did not affect community-wide microbial activity patterns and did not interact with the effects of crab burrows. The novel artificial crab burrow-mimics replicated these results, where organic matter and carbon to nitrogen ratios did not change over the experiment course whilst redox did. Differences in carbon-utilization by microbial communities between artificial burrow walls and bulk sediment mimicked those between natural crab burrow walls and bulk sediment. Hence, in the environmental settings of this study, it was the presence of burrow structures rather than crabs that induced changes in microbial communities.