David Porinchu

David Porinchu
University of Georgia | UGA · Department of Geography

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72
Publications
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Publications

Publications (72)
Article
Full-text available
Two lake cores from Khajjiar (length 746 cm) and Rewalsar lakes (length 647 cm) in Himachal Pradesh (India) were retrieved to understand the sedimentological characteristics and variation in grain size distribution. Both the lake cores are Upper Holocene in age. The Rewalsar lake sediments are composed predominantly of silt with small amounts of cl...
Article
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High-resolution analysis of a 3.80 m sediment core recovered from Deoria Tal, a mid-elevation lake located at 2393 m a.s.l. in the Garhwal Himalaya, documents long-term and abrupt hydroclimate fluctuations in northern India during the mid- to late Holocene. The sediment chronology, based on ten 14C dates, indicates the core spans 5200 years. Non-de...
Article
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Analyses of macroscopic charcoal, sediment geochemistry (%C, %N, C/N, δ ¹³ C, δ ¹⁵ N), and fossil pollen were conducted on a sediment core recovered from Stella Lake, Nevada, establishing a 2000 year record of fire history and vegetation change for the Great Basin. Charcoal accumulation rates (CHAR) indicate that fire activity, which was minimal fr...
Article
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
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Mountains of the arid Great Basin region of Nevada are home to critical water resources and numerous species of plants and animals. Understanding the nature of climatic variability in these environments, especially in the face of unfolding climate change, is a challenge for resource planning and adaptation. Here, we utilize an Embedded Sensor Netwo...
Article
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
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A comprehensive database of paleoclimate records is needed to place recent warming into the longer-term context of natural climate variability. We present a global compilation of quality-controlled, published, temperature-sensitive proxy records extending back 12,000 years through the Holocene. Data were compiled from 679 sites where time series co...
Article
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Multiproxy analysis of two sediment cores recovered from lagos Morrenas 3C and Ditkebi, located in the páramo of Costa Rica's Chirripó National Park, was undertaken to develop multidecadal-scale reconstructions of late Holocene fire regimes for the region. Analysis of macroscopic charcoal and sediment geochemistry (C%, N%, δ ¹³ C, δ ¹⁵ N, and C/N r...
Article
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Anthropogenic activities have led to a global decline in biodiversity, and monitoring studies indicate that both insect communities and wetland ecosystems are particularly affected. However, there is a need for long‐term data (over centennial‐ or millennial timescales) to better understand natural community dynamics and the processes that govern th...
Article
Multi-proxy analysis of a sediment core recovered from Lago Ditkebi in Chirripó National Park, Costa Rica, was undertaken to develop a multi-decadal to sub-centennial-scale reconstruction of Holocene hydroclimate and environmental change for the region. Analyses of sub-fossil chironomid assemblages, macroscopic charcoal, and bulk sediment geochemis...
Article
High resolution analysis of subfossil chironomid remains preserved in well-dated lacustrine sediment cores was undertaken to identify whether marked shifts in chironomid assemblages have occurred in recent decades in the Colorado Rocky Mountains. This study will improve our understanding of site-specific aquatic ecosystem variability in the central...
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California has experienced a dry 21(st) century capped by severe drought from 2012 through 2015 prompting questions about hydroclimatic sensitivity to anthropogenic climate change and implications for the future. We address these questions using a Holocene lake sediment record of hydrologic change from the Sierra Nevada Mountains coupled with marin...
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A lake sediment profile spanning the last ~3200 years from Laguna Zoncho in the southern Pacific region of Costa Rica was analyzed for sub-fossil chironomids. Notable shifts in chironomid assemblages occurred during the late-Holocene. A distinct chironomid community, dominated by Tanypodinae such as Procladius and Labrundinia, appeared after ~550 c...
Article
Chironomid assemblages from the uppermost sediments of 435 lakes spanning northern North America were compared to environmental parameters using direct gradient analysis. This large calibration set was merged from several previously developed regional datasets, and increases the number of modern analogues that are available for use for paleoenviron...
Article
Chironomids have been shown to provide robust reconstructions of past temperature change and variability. This is the first study to assess the contemporaneous relationship between the distribution of sub-fossil chironomids and limnological and climatic parameters in Central America. Here, we describe the distribution of chironomids in a suite of 5...
Data
Chironomid assemblages from the uppermost sediments of 435 lakes spanning northern North America were compared to environmental parameters using direct gradient analysis. This large calibration set was merged from several previously developed regional datasets, and increases the number of modern analogues that are available for use for paleoenviron...
Article
Full-text available
The geochemistry of lake sediments was used to identify anthropogenic factors influencing aquatic ecosystems of sub-alpine lakes in the western United States during the past century. Sediment cores were recovered from six high-elevation lakes in the central Great Basin of the United States. The proxies utilized to examine the degree of recent anthr...
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In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean-atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010-2011, construction at Zieg...
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A sediment core representing the past two millennia was recovered from Stella Lake in the Snake Range of the central Great Basin in Nevada. The core was analyzed for sub-fossil chironomids and sediment organic content. A quantitative reconstruction of mean July air temperature (MJAT) was developed using a regional training set and a chironomid-base...
Article
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Chironomids (nonbiting midges) are used to develop centennial length temperature reconstructions for six subalpine and alpine lakes in the central Great Basin of the United States. Faunal turnover, assessed by detrended correspondence analysis (DCA), indicate that substantial compositional change in the midge communities has occurred during the pas...
Article
Sediments recovered from the Ziegler Reservoir fossil site in Snowmass Village, Colorado (USA) were analyzed for subfossil chironomids (or midges). The midge stratigraphy spans ~ 140–77 ka, which includes the end of Marine Oxygen Isotope Stage (MIS) 6 and all of MIS 5. Notable shifts in midge assemblages occurred during two discrete intervals: the...
Article
Paleoecological studies from Rocky Mountain high elevations encompassing the previous interglacial (MIS 5e) are rare. The ~ 10-m composite profile from the Ziegler Reservoir site (2705 m asl) of central Colorado allows us to determine paleoenvironments from MIS 6–MIS 4 using pollen assemblages that are approximately equivalent to marine oxygen isot...
Article
Research focusing on the effects of radiative forcing and associated feedback mechanisms to the contemporaneous Arctic environment has highlighted the need to improve our knowledge of past climate variations and their impacts on terrestrial and aquatic ecosystems. Recent work has documented the response of the Arctic to low frequency climate change...
Article
Alpine and subalpine aquatic ecosystems are highly susceptible to direct and indirect effects of climate change making them ideal study sites. We recovered a sediment core spanning the last 7,000 years from Stella Lake and a core of the last 100 years from Baker Lake in Great Basin National Park, Nevada, in 2005 and 2007. We examined the cores for...
Article
Sediment cores were recovered from Stella Lake and Baker Lake, sub-alpine lakes located in Great Basin National Park, NV, in 2005 and 2007, respectively. The cores were analyzed for subfossil chironomid (Insecta: Diptera: Chironomidae) remains. Chronologies for the sediment cores, developed using 210Pb, indicate the cores span the 20th century. The...
Article
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A sediment core spanning ∼ 7000 cal yr BP recovered from Stella Lake, a small sub-alpine lake located in Great Basin National Park, Nevada, was analyzed for subfossil chironomids (non-biting midges), diatoms, and organic content (estimated by loss-on-ignition (LOI)). Subfossil chironomid analysis indicates that Stella Lake was characterized by a wa...
Article
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The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ic...
Article
We describe the physical and chemical properties of sixty-one tundra lakes, sampled in a latitudinal transect (65-71°N, 105-108°W) across mainland and island regions of Nunavut, central Canadian Arctic, and examine the influence of geology, geography, climate, and vegetation on lake water chemistry. This dataset complements earlier limnological sur...
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The development of chironomid-based air temperature inference models in high latitude regions often relies on limited spatial coverage of meteoro-logical data and/or on punctual measurements of water temperature at the time of sampling. The use of simple linear regression to relate air temperature and latitude was until recently the best method to...
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Subfossil midge remains were identified in surface sediment recovered from 88 lakes in the central Canadian Arctic. These lakes spanned five vegetation zones, with the southern-most lakes located in boreal forest and the northern-most lakes located in mid-Arctic tundra. The lakes in the calibration are characterized by ranges in depth, summer surfa...
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A lake sediment core recovered from Lake V57 on Victoria Island, Nunavut, Canada, spanning the last 2000years, was analyzed for sub-fossil midge remains and organic-matter content (estimated by loss-on-ignition (LOI)). Significant changes in midge community composition occurred during the last 2000years, with a distinct midge community appearing af...
Article
Our intent is to assess whether widely recorded thermal events such as the widespread cooling typical of the Little Ice Age (LIA ~1300 to 1850 AD) and the recent warming of the 20th century are captured in lake records in the central Canadian Arctic. Instrumental climate records from the central Canadian treeline zone display a pattern of variation...
Article
Sediment records from two lakes in the east-central Sierra Nevada, California, provide evidence of cooling and hydrological shifts during the Younger Dryas stade (YD; ~ 12,900–11,500 cal yr BP). A chironomid transfer function suggests that lake-water temperatures were depressed by 2°C to 4°C relative to maximum temperatures during the preceding Bøl...
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Instrumental climate records from the central Canadian treeline zone display a pattern of variation similar to general Northern Hemisphere temperature trends. To examine whether this general correspondence extends back beyond the instrumental record, we obtained a sediment core from Lake S41, a small lake in the Northwest Territories of Canada at 6...
Poster
The Arctic and sub-Arctic regions are experiencing dramatic changes in surface temperature, sea-ice extent, glacial melt, river discharge, soil carbon storage and snow cover. According to the IPCC high latitude regions are expected to warm between 4°C and 7°C over the next 100 years. The magnitude of warming and the rate at which it occurs will dwa...
Article
Subfossil midge analyses have been used to develop high-resolution (sub-decadal) reconstructions of 20th century temperature change in the Sierra Nevada, CA with success. Expansion of this earlier work to additional sites in the western United States suggests that a widespread increase in lake water temperatures has occurred in this region during t...
Article
Surface sediment recovered from 51 lakes in the Uinta Mountains of northeast Utah was analyzed for subfossil chironomid remains, and incorporated in a midge-based inference model for summer surface water temperature (SSWT). The lakes in the calibration set spanned elevation, depth, and summer surface water temperature ranges of 900 m, 12.7 m, and 1...
Article
High-resolution chironomid (Insecta: Diptera) stratigraphies were developed for three subalpine lakes in the Sierra Nevada of California to assess whether these lakes have been impacted by recent climate change evident in regional instrumental records for the 19th and 20th centuries. Detrended correspondence analysis (DCA) of the chironomid fauna i...
Article
Aquatic systems in alpine and sub-alpine areas of the western United States are potentially impacted by atmospheric pollution and climate change. Because these mountainous regions are an important water resource for the western United States, it is critical to monitor and protect these systems. The Uinta Mountains are an east- west trending mountai...
Article
High-resolution chironomid stratigraphies were developed for six sub-alpine lakes in the Great Basin of the western United States to assess whether high elevation lakes in this region have been affected by recent climate change. Detrended correspondence analysis (DCA) of the chironomid faunal assemblages indicates that these lakes experienced simil...
Article
Chironomid remains from a mid-elevation lake in the Sierra Nevada, California, were used to estimate quantitative summer surface water temperatures during the past not, vert, similar15,000 yr. Reconstructed temperatures increased by not, vert, similar3°C between lake initiation and the onset of the Holocene at not, vert, similar10,600 cal yr BP (ca...
Article
Instrumented lake and watershed climatic data along with lake sediment surface samples and cores are being used to develop and apply paleolimnological transfer functions to reconstruct climate change and ecosystem response in the eastern Sierra Nevada Mountains of California and the Unita Mountains of Utah. The selection of the two ranges provides...
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The spatio-temporal pattern of peak Holocene warmth (Holocene thermal maximum, HTM) is traced over 140 sites across the Western Hemisphere of the Arctic (0–180°W; north of ∼60°N). Paleoclimate inferences based on a wide variety of proxy indicators provide clear evidence for warmer-than-present conditions at 120 of these sites. At the 16 terrestrial...
Article
Drought has had disastrous impacts on western North American ecosystems, economies and society, and for many regions is predicted to be a likely consequence of future climate change. The instrumental record, however, spans too short a period to provide the full range of drought variability (including frequency, duration and magnitude), which is cri...
Article
Chironomid and stratigraphic analyses of a lake sediment core recovered from a high-elevation lake in the central Sierra Nevada, California, USA, was undertaken to assess chironomid community development during the Pleistocene–Holocene transition and to quantitatively reconstruct the thermal regime that existed during this interval. Between 14 800...
Article
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The potential of applying the analysis of freshwater midges (Chironomidae) for current questions in geographical research is examined. Chironomids are cosmopolitan in distribution and frequently the most abundant insects found in freshwater ecosystems. The capacity of the family to tolerate large gradients of pH, salinity, depth, oxygen concentrati...
Article
Full-text available
The potential of applying the analysis of freshwater midges (Chironomidae) for current questions in geographical research is examined. Chironomids are cosmopolitan in distribution and frequently the most abundant insects found in freshwater ecosystems. The capacity of the family to tolerate large gradients of pH, salinity, depth, oxygen concentrati...
Article
Physical, chemical, and biological data were collected from a suite of 57 lakes that span an elevational gradient of 1360 m (2115 to 3475 m a.s.l.) in the eastern Sierra Nevada, California, USA as part of a multiproxy study aimed at developing transfer functions from which to infer past drought events. Multivariate statistical techniques, including...
Article
Surface lake sediment was recovered from 57 lakes along an elevation gradient in the central, eastern Sierra Nevada of California. The surface sediment was analysed for subfossil chironomid remains in order to assess the modern distribution of chironomids in the region. The lakes sampled for the calibration dataset were between 2.0 and 40.0 m in de...
Article
Analysis of midge remains in late-Quaternary sediment, recovered from a lake situated north of treeline in northeast Siberia, indicates the occurrence of notable climatic fluctuations during the last 12 ka. The onset of late-glacial warming was disrupted by a marked cooling event – possibly correlative with the Younger Dryas – that occurred between...
Article
The development of increasingly refined paleoclimatic proxies and the use of fine-resolution temporal analysis has led to vastly improved lake sediment records of the rapid climatic changes that occurred during the last glacial-interglacial transition. The application of these more sophisticated paleolimnological analyses has produced exciting new...
Article
Surficial sediment from 31 lakes along a transect spanning treeline in northeast Siberia was analyzed for midge remains in order to assess the modern distribution of midges relative to treeline. Taxa distinct to tundra, forest-tundra, and forest areas were identified. Abiskomyia, Parakiefferiella nigra, and Hydrobaenus/Oliveridia were found predomi...
Article
Surficial sediment from 31 lakes along a transect spanning treeline in northeast Siberia was analyzed for midge remains in order to assess the modern distribution of midges relative to treeline. Taxa distinct to tundra, forest-tundra, and forest areas were identified. Abiskomyia, Parakiefferiella nigra, and Hydrobaenus/Oliveridia were found predomi...

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