Staff Profiles

Joe has a wide range of teaching experience across both undergraduate and postgraduate level.

He currently contributes to the following modules:

• U21104: Introduction to Environmental Geography
• U21106: Concepts in Geography
• U21126: Geographical Enquiry and Field Research
• U21148: Independent Study:Work and Community Related Learning
• U21173: Expedition
• U21180: Geographical Research & Practice
• U21198: Geography Dissertation

Journal articles

• McLauchlan KK, Lascu I, Mellicant E, Scharping RJ, Williams JJ, 'Influences of forested and grassland vegetation on Late Quaternary ecosystem development as recorded in lacustrine sediments'
  Quaternary Research (2019)
  ISSN: 0033-5894 eISSN: 1096-0287
  Abstract

  Geosphere-biosphere interactions are ubiquitous features of the Earth surface, yet the development of interactions between newly exposed lithologic surfaces and colonizing plants during primary succession after glaciation are lacking temporal detail. To assess the nature, rate, and magnitude of vegetation influence on parent material and sediment delivery, we analyzed ecosystem and geochemical proxies from lacustrine sediment cores at a grassland site and a forested site in the northern United States. Over time, terrigenous inputs declined at both sites, with increasing amounts of organic inputs toward present. The similarities between sites were striking given that the grassland sequence began in the Early Holocene, and the forested sequence began after the last glacial maximum. Multiple mechanisms of chemical weathering, hydrologic transport, and changes in source material potentially contribute to this pattern. Although there were strong links between vegetation composition and nitrogen cycling at each site, it appears that changes in forest type, or from oak woodland to grassland, did not exert a large influence on elemental (K, Ti, Si, Ca, Fe, Mn, and S) abundance in the sedimentary sequences. Rather, other factors in the catchment-lake system determined the temporal sequence of elemental abundance.

  Website 
• Valencia B, Matthews-Bird F, Urrego D, Williams J, Gosling W, Bush M, 'Andean microrefugia: testing the Holocene to predict the Anthropocene'
  New Phytologist 212 (2) (2016) pp.510-522
  ISSN: 0028-646X
  Abstract Microrefugia are important for supporting populations during periods of unfavourable climate change and in facilitating rapid migration as conditions ameliorate. With ongoing anthropogenic climate change, microrefugia could have an important conservation value; however, a simple tool has not been developed and tested to predict which settings are microrefugial. We provide a tool based on terrain ruggedness modelling of individual catchments to predict Andean microrefugia. We tested the predictions using nine Holocene Polylepis pollen records. We used the mid-Holocene dry event, a period of peak aridity for the last 100 000 yr, as an analogue climate scenario for the near future.
  The results suggest that sites with high terrain rugosity have the greatest chance of sustaining mesic conditions under drier-than-modern climates. Fire is a feature of all catchments; however, an increase in fire is only recorded in settings with low rugosity. Owing to rising temperatures and greater precipitation variability, Andean ecosystems are threatened by increasing moisture stress. Our results suggest that high terrain rugosity helps to create more resilient catchments by trapping moisture through orographic rainfall and providing firebreaks that shelter forest from fire. On this basis, conservation policy should target protection and management of catchments with high terrain rugosity.Website 
• Williams J, McLauchlan K, Mueller J, Mellicant E, Myrbo A, Lascu I, 'Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA'
  Quaternary Science Reviews 125 (2015)
  ISSN: 0277-3791
  Abstract Processes and rates of ecosystem development can be reconstructed using lacustrine sedimentary sequences, but this approach often requires records that contain the start of primary succession. Most lakes in the upper Midwestern U.S. were formed by glaciers at the end of the last Ice Age approximately 11,700 cal yr BP. Devils Lake, Wisconsin is a rare example of a lake from this region whose sediments extend into the Pleistocene and may include the Last Glacial Maximum. Sediment magnetic, geochemical, pollen, and charcoal records were generated from a 10 m core whose basal sediments may be 28,000 years old. Together with a previously published pollen record, these proxies combine to reveal a history of long-term climatic, vegetative and geologic change during the late Pleistocene to Holocene. We identify six sedimentary units that indicate a series of consecutive events rather than a predictable trajectory of ecosystem development at the site. Productivity in the lake was low during the late Pleistocene and increased during the Holocene, as reflected by the sediment lithology, which shows a sudden shift from glacial vivianite-rich and organic-poor clastic-dominated sediments to Holocene diatomaceous sapropels. Several important processes initiated around 17,000 cal yr BP, including the onset of organic matter accumulation and fire in the terrestrial ecosystem. However, the post-glacial landscape was not devoid of vegetation because pollen assemblages indicate that terrestrial vegetation, likely a spruce tundra, survived near the site. A switch to a hardwood forest period during the Holocene also led to a change in the fire regime, with increased frequency of burning. Aquatic ecosystem productivity lagged terrestrial ecosystem productivity throughout the record. Nutrient cycling (as recorded by sedimentary δ¹⁵N) was variable but not directional, and appeared to be correlated with climate conditions early in the record, and terrestrial ecosystem processes later in the record. Throughout the Holocene magnetic mineral concentration decreased as productivity increased, and the source of magnetic material shifted from almost exclusively lithogenic to approximately 50% derived from soil or biogenic sources. Magnetic grain size, Ambrosia pollen percentages, and charcoal concentration increased and δ¹⁵N decreased in the most recent part of the record, due to anthropogenic influence in the region including agricultural activities.Website 
• Mueller J, Long C, Williams J, Nurse A, Mclauchlan K, 'The relative controls on forest fires and fuel source fluctuations in the Holocene deciduous forests of southern Wisconsin, USA'
  Journal of Quaternary Science 29 (6) (2014) pp.561-569
  ISSN: 0267-8179
  Abstract Reconstructing fire regimes and fuel characteristics is an important aspect of understanding past forest ecosystem processes. Fuel sources and fire regimes in the upper Midwestern United States have been shown to be sensitive to regional climatic variability, such as drought periods on millennial timescales. Yet, records documenting the connections between disturbance activity and the corresponding fuel source fluctuations in mesic deciduous forests and prairie/oak savanna in this region are limited. Thus, it has been difficult to provide a framework to evaluate changes in moisture availability on fire activity and the relationships with fuel source fluctuations in this region. We present high-resolution charcoal analyses of lake sediments from four sites in southern Wisconsin (USA) to characterize fire activity and fuel source fluctuation in mesic deciduous forests and prairie/oak savanna over the last 10 000 years. We found that fire occurrence across the four study sites has been asynchronous throughout the Holocene, because of site-specific differences that have strongly influenced local fire regimes. Additionally, we found that during periods of high fire activity the primary fuels were from arboreal sources, and during periods of low fire activity the primary fuels were from non-arboreal sources. However, fluctuations in fuel sources did not always correspond to changes in vegetation, or changes in fire frequency.Website 
• McLauchlan K, Higuera P, Gavin D, Perakis S, Mack M, Alexander H, Battles J, Biondi F, Buma B, Colombaroli D, Enders S, Engstrom D, Hu F, Marlon J, Marshall J, McGlone M, Morris J, Nave L, Shuman B, Smithwick E, Urrego D, Wardle D, Williams C, Williams J, 'Reconstructing disturbances and their biogeochemical consequences over multiple timescales'
  BioScience 64 (2) (2014) pp.105-116
  ISSN: 0006-3568 eISSN: 525-3244
  Abstract Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.Website 
• Keen H, Gosling W, Hanke F, Miller C, Montoya E, Valencia B, Williams J, 'A statistical sub-sampling tool for extracting vegetation community and diversity information from pollen assemblage data'
  Palaeogeography, Palaeoclimatology, Palaeoecology 408 (2014) pp.48-59
  ISSN: 0031-0182
  Abstract Pollen assemblages are used extensively across the globe, providing information on various characteristics of the vegetation communities that originally produced them, and how these vary temporally and spatially. However, anticipating a statistically based robust pollen count size, sufficient to characterise a pollen assemblage is difficult; particularly with regard to highly diverse pollen assemblages. To facilitate extraction of ecologically meaningful information from pollen assemblage data, a two part statistical sub-sampling tool has been developed (Models 1 and 2), which determines the pollen count size required to capture major vegetation communities of varying palynological richness and evenness, and the count size required to find the next not yet seen (rare) pollen taxa. The sub-sampling tool presented here facilitates the rapid assessment of individual pollen samples (initial information input of 100 pollen grains) and can, therefore, on a sample by sample basis achieve maximum effectiveness and efficiency. The sub-sampling tool is tested on fossil pollen data from five tropical sites.
  
  Results demonstrate that Model 1 predicts count sizes relating to palynological richness and evenness consistently. To characterise major vegetation community components model 1 indicates that, for samples with a lower richness and higher evenness lower count sizes than are considered standard can be used (< 300, e.g. 122); however, for samples of high richness and low evenness, higher count sizes are required (> 300, e.g. 870). Model 2 calculates the additional number of pollen grains needed to be counted to detect the next not yet seen pollen taxa, outputs were strongly related to input data count size as well as richness and evenness characteristics. We conclude that, given the temporal and spatial variations in vegetation communities and also pollen assemblages, pollen count sizes should be determined for each individual sample to ensure that effective and efficient data are generated and that detection of rare taxa is checked iteratively throughout the counting process.Website 
• McLauchlan K, Williams J, Craine J, Jeffers E, 'Changes in global nitrogen cycling during the Holocene epoch'
  Nature 495 (7441) (2013)
  ISSN: 0028-0836
  Website 
• Gosling W, Williams J, 'Ecosystem service provision sets the pace for pre-Hispanic societal development in the central Andes'
  Holocene 23 (11) (2013)
  ISSN: 0959-6836
  Website 
• McLauchlan K, Williams J, Engstrom D, 'Nutrient cycling in the palaeorecord: Fluxes from terrestrial to aquatic ecosystems'
  Holocene 23 (11) (2013)
  ISSN: 0959-6836
  Website 
• Williams J, Brooks S, Gosling W, 'Response of chironomids to late Pleistocene and Holocene environmental change in the eastern Bolivian Andes'
  Journal of Paleolimnology 48 (3) (2012) pp.485-501
  ISSN: 0921-2728
  Abstract We present the first palaeolimnological investigation of chironomid larval assemblages from the Bolivian Eastern Cordillera. Taxonomic diagnoses are provided for the 10 chironomid taxa (subfamilies: Chironominae, Orthocladiinae and Tanypodinae) identified in the lake sediments. We compared changes in the chironomid assemblage from two Andean sites with previously reported palynological, charcoal and geochemical data, and highlight the potential of chironomid analysis to provide additional insights into environmental change in this region of high biodiversity over the last 18,000 years. At Lake Challacaba (17°33.257′S, 65°34.024′W; 3,400 m asl), the chironomid and geochemical data indicate periodic desiccation and hypersalinty of the basin c. 4,000–3,460 cal year BP. Increased abundance of Chironomus sp. at c. 1,000 cal year BP suggests a change in human activity, supporting inferences from the pollen and spore records, which indicate elevated pastoral agriculture at this time. The greatest assemblage change in the chironomid record from Laguna Khomer Kocha Upper (17°16.514′S, 65°43.945′W; 4,153 m asl) occurred at c. 6,380 cal year BP, concomitant with an increase in marsh woodland taxa, wetter conditions and a rising lake level at the end of a Holocene dry event. There is no apparent response in the chironomid assemblage to burning, however, at the onset of this dry event (c. 10,000 cal year BP), which is the major transformative agent of the terrestrial vegetation. This study shows that chironomid assemblages in the tropical Andes responded to regional and local environmental changes, and in particular, that they were sensitive to adjustments in net moisture balance (water level fluctuations and salinity) and anthropogenic impacts (nutrient input). This suggests that within-lake processes are more important as drivers of chironomid assemblage composition than terrestrial vegetation or fire regime. Nevertheless, the full potential of subfossil chironomid analysis will only be realised once more modern autecological data are available.Website 
• Williams J, Morris J, Perakis S, 'Reconstructing the biogeochemical consequences of disturbances'
  Eos 93 (47) (2012) pp.476-
  ISSN: 0096-3941 eISSN: 2324-9250
  Abstract Paleo Reconstructions of Biogeochemical Environments (PROBE) Workshop;Manhattan, Kansas; 19–21 April 2012 Disturbances—discrete events that reduce plant biomass—commonly regulate material and energy flow in terrestrial ecosystems. Recent studies document an increase in the size and/or severity of disturbances such as native bark beetle outbreaks and large fires compared to the recent past. However, scientists cannot evaluate the potential consequences of these events for ecosystem dynamics without decadal to multimillennial records of disturbances and ecosystem response. The Paleo Reconstructions of Biogeochemical Environments (PROBE) workshop brought together ecosystem ecologists and paleoecologists for a 3-day workshop at the Konza Prairie Biological Station in Manhattan, Kansas. The focus of the meeting was the reconstruction of the biogeochemical consequences of disturbances (e.g., beetle outbreaks, wildfires, windstorms, and droughts) on different timescales, the assessment of the state of current knowledge, and identification of challenges and opportunities for future research.Website 
• Williams J, Gosling W, Coe A, Brooks S, Gulliver P, 'Four thousand years of environmental change and human activity in the Cochabamba Basin, Bolivia'
  Quaternary Research 76 (1) (2011) pp.58-68
  ISSN: 0033-5894
  Abstract The Cochabamba Basin (Bolivia) is on the ancient road network connecting Andean and lowland areas. Little is known about the longevity of this trade route or how people responded to past environmental changes. The eastern end of the Cochabamba valley system constricts at the Vacas Lake District, constraining the road network and providing an ideal location in which to examine past human–environmental interactions. Multiproxy analysis of sediment from Lake Challacaba has allowed a c. 4000 year environmental history to be reconstructed. Fluctuations in drought tolerant pollen taxa and calcium carbonate indicate two periods of reduced moisture availability (c. 4000–3370 and c. 2190–1020 cal yr BP) compared to adjacent wetter episodes (c. 3370–2190 and c. 1020 cal yr BP–present). The moisture fluctuations broadly correlate to El Niño/Southern Oscillation variations reported elsewhere. High charcoal abundance from c. 4000 to 2000 yr ago indicates continuous use of the ancient road network. A decline in charcoal and an increase in dung fungus (Sporormiella) c. 1340–1210 cal yr BP, suggests that cultural changes were a major factor in shaping the modern landscape. Despite undisputable impacts of human populations on the Polylepis woodlands today, we see no evidence of woodland clearance in the Challacaba record.Website 
• Williams J, Gosling W, Brooks S, Coe A, Xu S, 'Vegetation, climate and fire in the eastern Andes (Bolivia) during the last 18,000years'
  Palaeogeography, Palaeoclimatology, Palaeoecology 312 (1/2) (2011) pp.115-126
  ISSN: 0031-0182
  Abstract A c. 18 ka cal BP long sediment record from Laguna Khomer Kocha Upper (4153 m asl), Bolivia, shows that fire regime, governed by climatic variation, has long been a transformative agent in the eastern Andes. Before c. 14.5 ka cal BP, warming and relatively moist conditions free from fire, facilitated the expansion of high Andean Polylepis woodland. Fire onset at c. 14.5.ka cal BP, quickly transformed the local vegetation and the woodlands became restricted to areas protected from fire. A major increase in burning, c. 10.1–6.4 ka cal BP removed Polylepis woodland locally and this coincided with a region-wide Holocene dry event (HDE) which caused falling lake levels and allowed fire intensification. A decline in burning at c. 6.4 ka cal BP and an increase in marsh–woodland (Alnus) marked the termination of the HDE and a return to wetter conditions. As well as recording the environmental history of local vegetation dynamics, long-distance pollen transport provides evidence of changes in the Yungas montane forests, highlighting their sensitivity to climate and burning regimes. Simultaneous adjustments in both Andean and Yungas montane taxa suggest that vegetation dynamics in the two environments are linked to a common climatic driver. There is no evidence to indicate that human activity had any impact on the local landscape.Website 

Other experience

Joe graduated from the University of Southampton with a BSc degree in Geography (2006), with interests in Quaternary environmental change and montane ecosystems. He obtained a PhD from the Open University (2011), in partnership with the Natural History Museum, London, with doctoral research involving travel to the Bolivian and Ecuadorian Tropical Andes, and work on high elevation lake cores.

Joe undertook postdoctoral research at Kansas State University, investigating the long-term dynamics of terrestrial and aquatic ecosystems in response to climatic and anthropogenic disturbances via the use of biological and biogeochemical sedimentary markers.

Between 2012-2017 he held a lectureship positon in Physical Geography and Environmental Science at Aberystwyth University.

Further information