A test of naturalness indicator values to evaluate success in grassland restoration

How should the somewhat vague term of restoration success be measured? This is a critical question rooted in European law, where in fact the creation of proper replacement habitats is a prerequisite for permitting projects that trigger a loss of species or habitats. Previous studies have used indices that relied on a comparison to reference sites, for example the number of a predefined pool of target species or compositional similarity. However, since restoration sites have rarely the same biotic and abiotic conditions as reference sites, plant communities in restored sites will not perfectly match the reference sites. Furthermore, such indices fail when reference sites are lacking or degraded. Hence, there is a need for an alternative approach that evaluates the conservation value of a restored site independently from reference sites. We propose that naturalness indicator values can be an option to measure restoration success. The approach of using naturalness indicator values makes use of the fact that plants are able to indicate environmental parameters, including degradation and regeneration. We compared and measured the restoration success of three well-established methods for grassland restoration (sod transplantation, hay transfer, seeding) with three commonly used indices (diversity, number of target species, similarity to reference sites). The results verified earlier studies and showed that sod transplantation led to the highest restoration success followed by hay transfer and seeding of sitespecific seed mixtures. Further, we used those well-established indices for an evaluation of novel, naturalness-based indices (unweighted and cover-weighted mean naturalness indicator values, the sum of naturalness indicator values). While calculating the means of naturalness indicator values failed to offer conclusive information on restoration success, we could show that the sum of naturalness indicator values was highly correlated with the number of target species and compositional similarity to reference sites. Thus, our case study demonstrated that naturalness indices can be an excellent option to estimate success in grassland restoration

The 6 April 2009 earthquake at L'Aquila: a preliminary analysis of magnetic field measurements

Several investigations reported the possible identification of anomalous geomagnetic field signals prior to earthquake occurrence. In the ULF frequency range, candidates for precursory signatures have been proposed in the increase in the noise background and polarization parameter (i.e. the ratio between the amplitude/power of the vertical component and that one of the horizontal component), in the changing characteristics of the slope of the power spectrum and fractal dimension, in the possible occurrence of short duration pulses. We conducted, with conventional techniques of data processing, a preliminary analysis of the magnetic field observations performed at L'Aquila during three months preceding the 6 April 2009 earthquake, focusing attention on the possible occurrence of features similar to those identified in previous events. Within the limits of this analysis, we do not find compelling evidence for any of the features which have been proposed as earthquake precursors: indeed, most of aspects of our observations (which, in some cases, appear consistent with previous findings) might be interpreted in terms of the general magnetospheric conditions and/or of different sources

Electron scale structures and magnetic reconnection signatures in the turbulent magnetosheath

Collisionless space plasma turbulence can generate reconnecting thin current sheets as suggested by recent results of numerical magnetohydrodynamic simulations. The MMS mission provides the first serious opportunity to check if small ion-electron-scale reconnection, generated by turbulence, resembles the reconnection events frequently observed in the magnetotail or at the magnetopause. Here we investigate field and particle observations obtained by the MMS fleet in the turbulent terrestrial magnetosheath behind quasi-parallel bow shock geometry. We observe multiple small-scale current sheets during the event and present a detailed look of one of the detected structures. The emergence of thin current sheets can lead to electron scale structures where ions are demagnetized. Within the selected structure we see signatures of ion demagnetization, electron jets, electron heating and agyrotropy suggesting that MMS spacecraft observe reconnection at these scales

The 6 April 2009 earthquake at L’Aquila: a preliminary analysis of magnetic field measurements

Several investigations reported the possible identification of anomalous geomagnetic field signals prior to earthquake occurrence. In the ULF frequency range, candidates for precursory signatures have been proposed in the increase in the noise background and polarization parameter (i.e. the ratio between the amplitude/power of the vertical component and that one of the horizontal component), in the changing characteristics of the slope of the power spectrum and fractal dimension, in the possible occurrence of short duration pulses. We conducted, with conventional techniques of data processing, a preliminary analysis of the magnetic field observations performed at L’Aquila during three months preceding the 6 April 2009 earthquake, focusing attention on the possible occurrence of features similar to those identified in previous events. Within the limits of this analysis, we do not find compelling evidence for any of the features which have been proposed as earthquake precursors: indeed, most of aspects of our observations (which, in some cases, appear consistent with previous findings) might be interpreted in terms of the general magnetospheric conditions and/or of different sources

Observations of whistler mode waves with nonlinear parallel electric fields near the dayside magnetic reconnection separatrix by the Magnetospheric Multiscale mission

We show observations from the Magnetospheric Multiscale (MMS) mission of whistler mode waves in the Earth's low-latitude boundary layer (LLBL) during a magnetic reconnection event. The waves propagated obliquely to the magnetic field toward the X line and were confined to the edge of a southward jet in the LLBL. Bipolar parallel electric fields interpreted as electrostatic solitary waves (ESW) are observed intermittently and appear to be in phase with the parallel component of the whistler oscillations. The polarity of the ESWs suggests that if they propagate with the waves, they are electron enhancements as opposed to electron holes. The reduced electron distribution shows a shoulder in the distribution for parallel velocities between 17,000 and 22,000 km/s, which persisted during the interval when ESWs were observed, and is near the phase velocity of the whistlers. This shoulder can drive Langmuir waves, which were observed in the high-frequency parallel electric field data