Quantifying carbon allocation to mycorrhizal fungi by temperate forest tree species across a nitrogen availability gradient

Terrestrial ecosystems make up the largest carbon pool with a major portion of that being forests. With carbon being a major concern due to global climate change, being able to make accurate models is increasingly important. Studies have shown that trees may allocate up to 50% of their photosynthetically fixed carbon underground; however these values haven’t been accurately quantified and underground carbon allocation has been historically overlooked. Mycorrhizal fungi may be a large portion of underground carbon allocation, as they have a symbiotic relationship with trees where they provide the plant with water and nutrients in return for sugars (carbon). New methods and knowledge will allow us to quantify carbon allocation and fungal biomass. Ergosterol is a biomarker that is the human equivalent of cholesterol for fungi which can be used to measure fungal biomass. Since both free-living and mycorrhizal fungi have ergosterol, a series of open and closed cores located at Bartlett Experimental Forest will separate the amount of ergosterol due to free-living versus mycorrhizal fungi. This is one of the first studies that will quantify fungal biomass and carbon allocation under a variation of natural settings and compare two different methods to estimate these values

Heating of the solar corona by the resonant absorption of Alfven waves

An improved method for calculating the resonance absorption heating rate is discussed and the results are compared with observations in the solar corona. The primary conclusion to be drawn from these calculations is that to the level of the approximation adopted, the observations of the heating rate and nonthermal line broadening in the solar corona are consistent with heating by the resonance absorption mechanism

Spatiotemporal organization of energy release events in the quiet solar corona

Using data from STEREO and SOHO spacecraft, we show that temporal organization of energy release events in the quiet solar corona is close to random, in contrast to the clustered behavior of flaring times in solar active regions. The locations of the quiet-Sun events follow the meso- and supergranulation pattern of the underling photosphere. Together with earlier reports of the scale-free event size statistics, our findings suggest that quiet solar regions responsible for bulk coronal heating operate in a driven self-organized critical state, possibly involving long-range Alfv\'{e}nic interactions.Comment: 5 pages, 4 figures, 1 tabl

Slow magnetosonic waves and fast flows in active region loops

Recent EUV spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (~100-300 km/s) quasi-periodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux-tubes and the establishment of siphon flow. We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.Comment: Accepted for publication in The Astrophysical Journa

The International Space Weather Initiative (ISWI)

The International Heliophysical Year (IHY) provided a successful model for the deployment of arrays of small scientific instruments in new and scientifically interesting geographic locations, and outreach. The new International Space Weather Initiative (ISWI) is designed to build on this momentum to promote the observation, understanding, and prediction space weather phenomena, and to communicate the scientific results to the public

Results from the International Heliophysical Year (IHY)

The International Heliophysical Year (IHY) involved the effort of thousands of scientists from over 70 countries, ended in February 2009. The major objectives of the IHY included over 60 collaborative studies of universal physical processes in the solar system, the deployment of arrays of small instruments to observe heliophysical processes, a unique program of educational and public outreach, and the preservation of the history of the IGY, during a two year period. A follow on effort, the International Space Weather Initiative (ISWI) is designed to build on the momentum developed during the IHY to develop the capability to observe, understand, and predict space weather phenomena