Indiana University-Purdue University Indianapolis (IUPUI) / Drylands are the largest terrestrial biome on the planet, and the critically important
systems that produce approximately 40% of global net primary productivity to support
nearly 2.5 billion of global population. Climate change, increasing populations and
resulting anthropogenic effects are all expected to impact dryland regions over the coming
decades. Considering that approximately 90% of the more than 2 billion people living in
drylands are geographically located within developing countries, improved understanding
of these systems is an international imperative. Although considerable progress has been
made in recent years in understanding climate change impacts on hydrological cycles,
there are still a large number of knowledge gaps in the field of dryland ecohydrology.
These knowledge gaps largely hinder our capability to better understand and predict how
climate change will affect the hydrological cycles and consequently the soil-vegetation
interactions in drylands.
The present study used recent technical advances in remote sensing and stable
isotopes, and filled some important knowledge gaps in the understanding of the dryland
systems. My study presents a novel application of the combined use of customized
chambers and a laser-based isotope analyzer to directly quantify isotopic signatures of transpiration (T), evaporation (E) and evapotranspiration (ET) in situ and examine ET
partitioning over a field of forage sorghum under extreme environmental conditions. We
have developed a useful framework of using satellite data and trend analysis to facilitate
the understanding of temporal and spatial rainfall variations in the areas of Africa where
the in situ observations are scarce. By using a meta-analysis approach, we have also
illustrated that higher concentrations of atmospheric CO2 induce plant water saving and the
consequent available soil water increases are a likely driver of the observed greening
phenomena. We have further demonstrated that Leuning’s modified Ball-Berry model and
RuBP limited optimization model can generally provide a good estimate of stomatal
conductance response to CO2 enrichment under different environmental conditions. All
these findings provide important insights into dryland water-soil-vegetation interactions.
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/17112 |
| Date | 03 April 2018 |
| Creators | Lu, Xuefei |
| Contributors | Wang, Lixin, Gilhooly, William P., Jacinthe, Pierre Andre, Li, Lin, Wilson, Jeffery |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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