Browsing by Author "D'Odorico, Paolo"

Now showing 1 - 5 of 5
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    Antarctica’s Dry Valleys: A potential source of soluble iron to the Southern Ocean?
    (AGU, 2015-03) Bhattachan, Abinash; Wang, Lixin; Miller, Molly F.; Licht, Kathy J.; D'Odorico, Paolo; Department of Earth Sciences, IU School of Science
    The soluble iron content and dust emission potential of sediment samples collected from the Taylor Valley in the McMurdo Dry Valleys (MDVs) and sea ice in the McMurdo Sound were evaluated to determine whether inputs to the Southern Ocean may be sufficient to affect ocean productivity. Our results show that the dust-generating potential from the MDVs soils are comparable to those of sediments from other major dust sources in the Southern Hemisphere. Sediments from the MDVs and sea ice are one order of magnitude richer in soluble iron than those in other dust sources in the Southern Hemisphere. Forward trajectory analyses show that the dust from the MDVs is likely to be deposited in the Southern Ocean. These results provide evidence of the possible supply of soluble iron to the Southern Ocean associated with dust transport from the MDVs, should climate change expand the exposed areas of the continent.
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    The competitive advantage of a constitutive CAM species over a C4 grass species under drought and CO2 enrichment
    (Wiley, 2019-05-15) Yu, Kailiang; D'Odorico, Paolo; Collins, Scott L.; Carr, David; Porporato, Amilcare; Anderegg, William R. L.; Gilhooly, William P.; Wang, Lixin; Bhattachan, Abinash; Bartlett, Mark; Hartzell, Samantha; Yin, Jun; He, Yongli; Li, Wei; Tatlhego, Mokganedi; Fuentes, Jose D.; Earth Sciences, School of Science
    Plants with crassulacean acid metabolism (CAM) are increasing in distribution and abundance in drylands worldwide, but the underlying drivers remain unknown. We investigate the impacts of extreme drought and CO2 enrichment on the competitive relationships between seedlings of Cylindropuntia imbricata (CAM species) and Bouteloua eriopoda (C4 grass), which coexist in semiarid ecosystems across the Southwestern United States. Our experiments under altered water and CO2 water conditions show that C. imbricata positively responded to CO2 enrichment under extreme drought conditions, while B. eriopoda declined from drought stress and did not recover after the drought ended. Conversely, in well-watered conditions B. eriopoda had a strong competitive advantage on C. imbricata such that the photosynthetic rate and biomass (per individual) of C. imbricata grown with B. eriopoda were lower relative to when growing alone. A meta-analysis examining multiple plant families across global drylands shows a positive response of CAM photosynthesis and productivity to CO2 enrichment. Collectively, our results suggest that under drought and elevated CO2 concentrations, projected with climate change, the competitive advantage of plant functional groups may shift and the dominance of CAM plants may increase in semiarid ecosystems.
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    Dryland productivity under a changing climate
    (Springer, 2022-11) Wang, Lixin; Jiao, Wenzhe; MacBean, Natasha; Rulli, Maria Cristina; Manzoni, Stefano; Vico, Giulia; D'Odorico, Paolo; Earth and Environmental Sciences, School of Science
    Understanding dryland dynamics is essential to predict future climate trajectories. However, there remains large uncertainty on the extent to which drylands are expanding or greening, the drivers of dryland vegetation shifts, the relative importance of different hydrological processes regulating ecosystem functioning, and the role of land-use changes and climate variability in shaping ecosystem productivity. We review recent advances in the study of dryland productivity and ecosystem function and examine major outstanding debates on dryland responses to environmental changes. We highlight often-neglected uncertainties in the observation and prediction of dryland productivity and elucidate the complexity of dryland dynamics. We suggest prioritizing holistic approaches to dryland management, accounting for the increasing climatic and anthropogenic pressures and the associated uncertainties.
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    Ecosystem-scale spatial heterogeneity of stable isotopes of soil nitrogen in African savannas
    (2013-04) Wang, Lixin; Okin, Gregory S.; D'Odorico, Paolo; Caylor, Kelly K.; Macko, Stephen A.
    Soil 15N is a natural tracer of nitrogen (N) cycling. Its spatial distribution is a good indicator of processes that are critical to N cycling and of their controlling factors integrated both in time and space. The spatial distribution of soil δ15N and its underlying drivers at sub-kilometer scales are rarely investigated. This study utilizes two sites (dry vs. wet) from a megatransect in southern Africa encompassing locations with similar soil substrate but different rainfall and vegetation, to explore the effects of soil moisture and vegetation distribution on ecosystem-scale patterns of soil δ15N. A 300-m long transect was set up at each site and surface soil samples were randomly collected for analyses of δ15N, %N and nitrate content. At each soil sampling location the presence of grasses, woody plants, Acacia species (potential N fixer) as well as soil moisture levels were recorded. A spatial pattern of soil δ15N existed at the dry site, but not at the wet site. Woody cover distribution determined the soil δ15N spatial pattern at ecosystem-scale; however, the two Acacia species did not contribute to the spatial pattern of soil δ15N. Grass cover was negatively correlated with soil δ15N at both sites owing to the lower foliar δ15N values of grasses. Soil moisture did not play a role in the spatial pattern of soil δ15N at either site. These results suggest that vegetation distribution, directly, and water availability, indirectly, affect the spatial patterns of soil δ15N through their effects on woody plant and grass distributions.
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    The interactive nutrient and water effects on vegetation biomass at two African savanna sites with different mean annual precipitation
    (2012-12) Wang, Lixin; Katjiua, Mutjinde; D'Odorico, Paolo; Okin, Gregory S.
    Savannahs cover more than 40% of Africa and provide a variety of important ecosystem services. Their productivity is constrained by disturbance and limiting resources. In southern Africa, fine-leaf savannahs typical of arid environments are known for being richer in nutrients than broad-leaf mesic savannahs. However, despite numerous recent studies on the dynamics of southern African savannahs, the interplay between water and nutrient limitations remains poorly investigated in these systems. To better understand the interactions between water, nutrients (N and P in this manuscript) and grazing on the productivity of grasses and trees in fine-leaf savannah ecosystems, a fertilization experiment with controlled grazing was conducted at two sites with different mean annual rainfall in Namibia. The experiment demonstrated that the vegetation at the drier site may not be nutrient-limited (N, P or N + P). At the wetter site, however, vegetation showed significant response to nutrient addition. Grasses exhibited N limitation and trees exhibited P limitation. This experiment also showed that grazing reduces the overall grass biomass, but may not modify the response to nutrient treatments. The results indicated a switch from water to nutrient limitation between dry and wet sites and demonstrated different tree and grass responses to nutrient additions.