Geo-Geography and Environment最新文献

The open collection “Aquatic transitions: Tracking the nature and trajectories of anthropogenically forced change in freshwater and coastal ecosystems” stems from a session of the same name at the ASLO (Association for the Sciences of Limnology and Oceanography) Aquatic Sciences Meeting 2017 in Honolulu, Hawai'i. The five papers gathered here reflect the focus of the special session on long-term ecosystem research and monitoring (LTERM), and collectively make use of monitoring data, palaeolimnology, and historical and documentary records to explore the timing, extent, and causes of human-related impacts on aquatic ecosystems. Collectively, they demonstrate that because timescales of ecological change often extend beyond contemporary monitoring, LTERM plays a crucial role in supporting evidence-based conservation. In this introduction, we reflect on the role that LTERM has had in each of the ecosystems studied, and discuss the opportunities for LTERM work to inform future conservation.

Rapid development and climate change in southeast Asia is placing unprecedented pressures on freshwater ecosystems, but long term records of the ecological consequences are rare. Here we examine one basin of Tasik Chini (Malaysia), a UNESCO-designated flood pulse wetland, where human disturbances (dam installation, iron ore mining, oil palm and rubber cultivation) have escalated since the 1980s. Diatom analysis and organic matter geochemistry (δ¹³C_org and C/N ratios) were applied to a sediment sequence to infer ecological changes in the basin since c. 1900 CE. As the Tasik Chini wetland is a rare ecosystem with an unknown diatom ecology, contemporary diatom habitats (plant surfaces, mud surfaces, rocks, plankton) were sampled from across the lake to help interpret the sedimentary record. Habitat specificity of diatoms was not strongly defined and, although planktonic and benthic groupings were distinctive, there was no difference in assemblages among the benthic habitat surfaces. An increase in the proportion of benthic diatom taxa suggests that a substantial decrease in water level occurred between c. 1938 and 1995 CE, initiated by a decline in rainfall (supported by regional meteorological data), which increased the hydrological isolation of the sub-basin. Changes in the diatom assemblages were most marked after 1995 CE when the Chini dam was installed. After this time both δ¹³C_org and C/N decreased, suggesting an increase in autochthonous production relative to allochthonous river flood pulse inputs. Oil palm plantations and mining continued to expand after c. 1995 CE and we speculate that inputs of pollutants from these activities may have contributed to the marked ecological change. Together, our work shows that this sub-basin of Tasik Chini has been particularly sensitive to, and impacted by, a combination of human and climatically induced changes due to its hydrologically isolated position.

As a feature of the Fish Revolution (1400–1700), the early modern “invention” of the Grand Banks in literary and cartographical documents facilitated a massive and unprecedented extraction of cod from the waters of the north Atlantic and created the Cod/Sack trade Triangle. This overlapped with the southern Atlantic Slave, Sugar, and Tobacco Triangle to capitalise modern European and North American societies. In 1719, Pierre de Charlevoix claimed that the Grand Banks was “properly a mountain, hid under water,” and noted its cod population “seems to equal that of the grains of sand which cover this bank.” However, two centuries later in 1992, in the face of the collapse of the fishery, and fearing its extinction, a moratorium was placed on five centuries of harvesting Grand Banks cod. The invention and mining of its waters serves as a bellwether for the massive resource extractions of modernity that drive the current leviathan and “wicked problem” of global warming. The digital environmental humanities narrative of this study is parsed together from 83 pieces of Grand Banks charting from 1504 to 1833, which are juxtaposed through Humanities GIS applications with English and French cod-catch records kept between 1675 and 1831, letters regarding Cabot's 1497 voyage, Shakespeare's The Tempest (1611) and scientific essays by De Brahms (1772) and Franklin (1786).

This paper explores the geographical distribution of independent and do-it-yourself information and communication technology maintenance and repair (INDIY ICT M&R) activity around the world. It examines a large set of Google Analytics data pertaining to users of free, open-source online repair manuals provided by iFixit, a US-based organisation that develops the free manuals, sells tools and components, and also engages in technical education and policy advocacy. The paper draws on three years of available user data (2016–2018). Over this time period the total user base of iFixit's manuals grew from over 1.3 million users to more than 4.1 million users across the planet. However, counter to what might be expected, the global distribution of iFixit users does not systematically co-vary with internet access rates or with the population size of locations. The results reported here, while partial, are valuable in that they demonstrate both a globally distributed phenomenon and high-resolution location patterns of INDIY ICT M&R activity. Mapping the extent and spatial patterning of such activity is a jumping off point for the kinds of qualitative analyses needed to elucidate the how's, the why's, and the meanings of the observed uneven distribution patterns. More broadly, the results suggest fruitful directions for deeper analyses and research into both pragmatic questions about ICT maintenance and repair (such as their social, economic, and environmental significance), as well as more speculative questions about how and why the fates of ICT within and between production, use, and discard stand in for dreams of technological futurity and nightmares of social and environmental breakdown.

Exploration of the underwater landscape in Lithuanian waters, in the eastern part of the Baltic Sea, allowed identification of trees stumps in growth position, peat sediments, and traces of people that were living in the now flooded landscape. The exploration has been concentrated on localisation of the former Early Holocene coasts. Based on new data about sediment layers of the Preboreal‒Atlantis I, palynological and dendrohronological analysis, identified vegetation species, and dating of wood and peat samples by radiocarbon methods the Baltic Sea water level dynamics during the stages Yoldia Sea‒Early Litorina Sea could be identified. There are traces of the eroded coasts of the Yoldia Sea at a depth of 39–43 m, which were also observed at depths of 44 and 47 m. During the Ancylus Lake transgression, the RF-I lagoons and small lakes with the peat layer and the surrounding forests were submerged. The water level could have even risen to 10–9 m below present sea level. The water drop during the Ancylus Lake regression is evidenced by a peat layer dated to 9,150–8,520 cal BP, and similar radiocarbon dating of an oak stump. The changes of the species composition of trees are indicative of the noticeable climate changes during the period 11,410–7,900 cal BP. Litorina transgression is marked by a tree stump found at a depth of 14.5 m dated to 7,900–7,660 cal BP. The preference of the Early Holocene population to the coastal zone is evidenced by poles driven into the seabed (one was dated to 9,510–9,460 cal BP) that were detected at a depth of 11 m and the T-shaped antler axes dated to the Early Neolithic, washed ashore from the Litorina Sea coastal Stone Age settlements.

Food vendors are pivotal in the local food system of most low-income informal settlements in Nairobi, Kenya, despite being seen as an obstruction and as agents of disease and filth by city authorities. This paper explores the geography of these foodscapes – defined as public sites of food production and consumption – in selected low-income settlements in Nairobi, focusing on the interaction of food vendors with their surrounding environment and infrastructure services. The research uses participatory geographic information system tools, including food mapping with mobile apps and high-resolution community aerial views with balloon mapping, to capture and contextualise local knowledge. The community mappers collected data on 660 vendors from 18 villages in Kibera, Mathare, and Mukuru, and situated them on multi-layered synoptic geographic overviews for each settlement. The resulting data on hazardous areas in relation to food spaces and infrastructure provision allowed local communities to prioritise areas for regular clean-up activities and assisted advocacy to improve these places in cooperation with local authorities. These multiple visual representations of foodscapes make local food vendors, and the risks they face, visible for the first time. Reframing their “right to safe food and environment” from a social and environmental justice perspective allows local communities to put their experiences, knowledge, and challenges faced at the forefront of urban development planning, policy, and practice.

A recent paper by Heinemeyer et al. (2018) in this journal has suggested that the use of prescribed fire may enhance carbon accumulation in UK upland blanket bogs. We challenge this finding based on a number of concerns with the original manuscript including the lack of an unburned control, insufficient replication, unrecognised potential confounding factors, and potentially large inaccuracies in the core dating approach used to calculate carbon accumulation rates. We argue that burn-management of peatlands is more likely to lead to carbon loss than carbon gain.

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