Time: 14:00 BST Tuesday, 22nd Jun 2021
14:00-16:00 London
Check your time here
1. Introduction
2. Talks [15 mins for each]
(1). Cancelled
Fire history and landscape changes in Northeast China and implications for present and future biodiversity
Qiaoyu Cui (Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences)
Short abstract: NA
(2). The human dimension of biodiversity changes on islands
Sandra Nogué ( University of Southampton )
Abstract: Islands are among the last regions on Earth settled and transformed by human activities, and they provide replicated model systems for analysis of how people affect ecological functions. By analyzing 27 representative fossil pollen sequences encompassing the past 5000 years from islands globally, we quantified the rates of vegetation compositional change before and after human arrival. After human arrival, rates of turnover accelerate by a median factor of 11, with faster rates on islands colonized in the past 1500 years than for those colonized earlier. This global anthropogenic acceleration in turnover suggests that islands are on trajectories of continuing change. Strategies for biodiversity conservation and ecosystem restoration must acknowledge the long duration of human impacts and the degree to which ecological changes today differ from prehuman dynamics.
------ Questions & Biobreak ------ [5-8 mins]
(3). Pollen-based quantitative paleoclimate record from a Chaohu lake sedimentary core since the Last Glacial Maximum, in the Lower Yangtze River catchment
Jia Sun ( Nanjing University )
Short abstract: In this presentation, we use the pollen indicators of lake sediments from the CZK core in Chaohu Lake to recover the vegetation assemblage succession in the Chaohu Lake area since the Last Glacial Maximum and quantitatively reconstruct the corresponding climate change characteristics. We hope this work could fill the blank of long-time pollen-based climatic record in the lower Yangtze River area.
(4). Global acceleration in rates of vegetation change over the past 18,000 years
Suzette Flantua & Ondrej Mottl ( University of Bergen )
Abstract: Global vegetation over the past 18,000 years has been transformed first by the climate changes that accompanied the last deglaciation and again by increasing human pressures; however, the magnitude and patterns of rates of vegetation change are poorly understood globally. Using a compilation of 1181 fossil pollen sequences and newly developed statistical methods, we detect a worldwide acceleration in the rates of vegetation compositional change beginning between 4.6 and 2.9 thousand years ago that is globally unprecedented over the past 18,000 years in both magnitude and extent. Late Holocene rates of change equal or exceed the deglacial rates for all continents, which suggests that the scale of human effects on terrestrial ecosystems exceeds even the climate-driven transformations of the last deglaciation. The acceleration of biodiversity change demonstrated in ecological datasets from the past century began millennia ago.
------ Questions & Biobreak------ [5-8 mins]
(5). Why quantitative reconstruction of vegetation matters ?
Furong Li ( Sun Yat-sen University )
Short abstract: In an attempt to quantify Holocene anthropogenic land-cover change in temperate China, we 1) applied the REVEALS model to estimate plant-cover change using 94 pollen records and relative pollen productivity for 27 plant taxa, 2) reviewed earlier interpretation of pollen studies in terms of climate- and human-induced vegetation change, and 3) reviewed information on past land use from archaeological studies. REVEALS achieved a more realistic reconstruction of plant-cover change than pollen percentages in terms of openland versus woodland. The study suggests successive human-induced changes in vegetation cover. The first signs of human- induced land-cover change (crop cultivation, otherwise specified) are found c. 7 ka BP in the temperate deciduous forest, and S and NE Tibetan Plateau (mainly grazing, possibly crop cultivation), 6.5–6 ka BP in the temperate steppe and temperate desert (grazing, uncertain), and 5.5–5 ka BP in the coniferous-deciduous mixed forest, NE subtropical region, and NW Tibetan Plateau (grazing). Further intensification of anthropogenic land-cover change is indicated 5–4.5 ka BP in the E temperate steppe, and S and NE Tibetan Plateau (grazing, cultivation uncertain), 3.5–3 ka BP in S and NE Tibetan Plateau, W temperate steppe, temperate desert (grazing), and NW Tibetan Plateau (probably grazing), and 2.5–2 ka BP in the temperate deciduous forest, N subtropical region, and temperate desert (grazing). These changes generally agree with increased human activity as documented by archaeological studies. REVEALS reconstructions have a stronger potential than biomization to evaluate anthropogenic land-cover change such as HYDE, given they are combined with information from archaeological studies.
(6). Widespread reforestation before European influence on Amazonia
Mark Bush ( Florida Institute of Technology )
Abstract: An estimated 90 to 95% of Indigenous people in Amazonia died after European contact. This population collapse is postulated to have caused decreases in atmospheric carbon dioxide concentrations at around 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery, and warfare, whereby the attendant reversion to forest substantially increased terrestrial carbon sequestration. On the basis of 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric carbon dioxide response after European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began about 300 to 600 years before European arrival. Pre-European pandemics, social strife, or environmental change may have contributed to these early site abandonments and ecological shifts.
------ Questions & Biobreak------ [5-8 mins]