Time：15:00 -16:00，26 September (Thursday)
Venue：Lecture Hall 221, Building No. 16, SESS, TJU
Speaker：Prof. Zhihong Xu from Griffith University
Abstract：
Tree water use efficiency (WUE) has increased globally in the past 150 years, but this has not been translated into global increases in tree growth consistently in space and time. Complex and dynamic forest ecosystems would respond non-linearly to climate change with multiple factors over a long period, and can have tipping points or critical boundaries / thresholds at which a sudden shift to a contrasting dynamic regime might occur. However, prediction of such critical points / thresholds before they are being reached is extremely difficult. Indeed, our comprehensive studies undertaken in the last 18 years (mostly unpublished) have shown for the first time that long-term tree growth of beech and oak in temperate central Europe (Belgium) responded non-linearly to rising atmospheric carbon (C) dioxide (CO2) and water (H2O) limitation. This is due to the increasing mean annual temperature and decreasing summer rainfall during 1840s–1990s. It is the initial CO2 fertilisation and then warming-induced water limitation that control tree growth under climate change. This would result in decreased forest CO2 assimilation and increasing atmospheric CO2, leading to accelerated global warming and increasing water limitation. It is interesting to note that the atmospheric CO2 tipping points for a given biome (such as tropical or temperate) would be influenced by both biotic (e.g. tree species and age) and abiotic factors (e.g. water and N availability).We have tested the CO2 fertilisation - warming-induced water limitation model globally, and our exciting major findings have highlighted that there is a widespread decline in tree growth beyond the tipping points of atmospheric CO2 in global forests under climate change.
About the speaker：
Zhihong Xu, Professor of Soil-Plant-Climate Systems and previous Director of Environmental Futures Research Institute, Griffith University. He is Editor in Chief of 《Journal of Soil and Sediments》, Editor in Chief of 《Environmental Science and Pollution Research》, and Chairman of Forest Soils Working Group of International Union of Soil Science. He mainly engaged in research on microbial communities and diversity, carbon and nitrogen cycling, and the impact of climate change on tree water use in forest ecosystems. More than 400 papers and 2 monographs have been published in top journals such as 《New Phytologist》, 《Soil Biology & Biochemistry》, 《Soil Science Society of America Journal》, 《Tree Physiology》, etc. in the fields of plant science, soil science, and forestry. He secured more than $24M of external funding support, with most coming from national competitive grants (including 10 Australian Research Council (ARC) Linkage grants, 4 ARC LIEF grants and 3 ARC Discovery grants).
