247 research outputs found
Climate change and ecohydrological processes in drylands : the effects of C02 enrichment, precipitation regime change and temperature extremes
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 Leuningâs 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
Evaluating ecohydrological modelling framework to link atmospheric CO2 and stomatal conductance
The establishment of an accurate stomatal conductance (gs) model in responding to CO2 enrichment under diverse environmental conditions remains an important issue as gs is the key to understand the plantâwaterâatmosphere interactions. A better representation of gs is important to reduce uncertainties in predicting the climate change impacts on various ecosystem functions. In this study, we evaluated three most commonly used gs formulations for the estimation of the stomatal response to environmental factors using in situ measurements under different environmental conditions. The three gs models were Leuning's modified BallâBerry model and two specific cases of the optimization models (i.e., Rubisco limitation model and RuBP regeneration limitation model). On the basis of an analysis of 234 data points obtained from experiments under instantaneous, semicontrolled, and the freeâair CO2 experiment conditions, we found that Leuning's modified BallâBerry model and RuBPâlimited optimization model showed similar performance, and both performed better than Rubisco limitation model. Functional groups (e.g., C3 vs. C4 species) and life form (e.g., annual vs. perennial species) play an important role in determining the gs model performance and thus pose a challenge for gs predictions in mixed vegetation communities
2d Regional Correlation Analysis Of Single-molecule Time Trajectories
We report a new approach of 2D regional correlation analysis capable of analyzing fluctuation dynamics of complex multiple correlated and anticorrelated fluctuations under a noncorrelated noise background. Using this new method, by changing and scanning the start time and end time along a pair of fluctuation trajectories, we are able to map out any defined segments along the fluctuation trajectories and determine whether they are correlated, anticorrelated, or noncorrelated; after which, a cross-correlation analysis can be applied for each specific segment to obtain a detailed fluctuation dynamics analysis. We specifically discuss an application of this approach to analyze single-molecule fluorescence resonance energy transfer (FRET) fluctuation dynamics where the fluctuations are often complex, although this approach can be useful for analyzing other types of fluctuation dynamics of various physical variables as well
Elevated CO2 as a driver of global dryland greening.
While recent findings based on satellite records indicate a positive trend in vegetation greenness over global drylands, the reasons remain elusive. We hypothesize that enhanced levels of atmospheric CO2 play an important role in the observed greening through the CO2 effect on plant water savings and consequent available soil water increases. Meta-analytic techniques were used to compare soil water content under ambient and elevated CO2 treatments across a range of climate regimes, vegetation types, soil textures and land management practices. Based on 1705 field measurements from 21 distinct sites, a consistent and statistically significant increase in the availability of soil water (11%) was observed under elevated CO2 treatments in both drylands and non-drylands, with a statistically stronger response over drylands (17% vs. 9%). Given the inherent water limitation in drylands, it is suggested that the additional soil water availability is a likely driver of observed increases in vegetation greenness
Probing Single-molecule Interfacial Geminate Electron-cation Recombination Dynamics
Interfacial electron-cation recombination in zinc-tetra (4-carboxyphenyl) porphyrin (ZnTCPP)/TiO(2) nanoparticle system has been probed at the single-molecule level by recording and analyzing photon-to-photon pair times of the ZnTCPP fluorescence. We have. developed a novel approach to reveal the hidden single-molecule interfacial electron-cation recombination dynamics by analyzing the autocorrelation function and a proposed convoluted single-molecule interfacial electron-cation recombination model. Our results suggest that the fluctuations of the interfacial electron transfer (ET) reactivity modulate the ET cycles as well as the interfacial electron-cation recombination dynamics. On the basis of this model, the single-molecule electron-cation recombination time of ZnTCPP/-TiO(2) system is deduced to be at time scale of 10(-5) s. The autocorrelation of photon-to-photon pair times as well as the convoluted ET model has been further demonstrated by simulation and interpreted in terms of the interfacial ET reactivity fluctuation and blinking. Our approach not only can effectively probe the single-molecule interfacial electron-cation dynamics but also can be applied to other single-molecule ground-state regeneration dynamics occurring at interfaces and within condensed phases
Biogeography of the Japanese Gourmet Fungus, Tricholoma matsutake: A Review of the Distribution and Functional Ecology of Matsutake
Tricholoma matsutake (S. Ito & S. Imai) Singer is an ectomycorrhizal basidiomycete that produces highly prized mushrooms known as âtrue matsutakeâ. Recent research has shown that T. matsutake has a wide but patchy distribution in temperate and boreal forests of Eurasia and subtropical China in association with Pinus, Picea, Tsuga, Abies and even fagaceous broadleaves. Molecular analyses of the microbial communities living in shiro soil have been made in certain locations, but their generality has yet to be determined systematically and across the entire range. Variation in fruiting in relation to climate and geography has improved our understanding of matsutake phenology, and important in-roads have been made into its ecology over the past 15Â years. T. matsutake is a commercially-important fungal species that plays a significant role in the functional diversity of forests in the Northern Hemisphere, but much remains to be learned about this enigmatic taxon.Peer reviewe
Suspended Lipid Bilayer For Optical And Electrical Measurements Of Single Ion Channel Proteins
Making and holding an artificial lipid bilayer horizontally in an aqueous solution within the microscopic working distance of similar to 100 mu m are essential for simultaneous single molecule imaging and single ion-channel electrical current recording. However, preparation of such a lipid bilayer without a solid support is technically challenging. In a typical supported lipid bilayer, the asymmetric local environments and the strong perturbation of the underneath solid or dense surface can diverge the normal behavior of membrane proteins and lipids. On the other hand, the suspended lipid bilayers can provide a native local environment for the membrane proteins and lipids by having fluids on both sides. In this technical report, we present a simple and novel methodology for making a suspended lipid bilayer that can be used for recording the single-molecule diffusion and single ion-channel electrical measurements of ion-channel proteins. Our approach has a higher validity for studying the molecular diffusions and conformational fluctuations of membrane proteins without having perturbations from supporting layers. We demonstrate the feasibility of such an approach on simultaneous single-molecule fluorescence imaging and electric current measurements of ion channel proteins
- âŠ