Forest Soil Carbon and Nitrogen Cycles under Biomass Harvest: Stability, Transient Response, and Feedback

Biomass harvest generates an imbalance in forest carbon (C) and nitrogen (N) cycles and the nonlinear biogeochemical responses may have long-term consequences for soil fertility and sustainable management. We analyze these dynamics and characterize the impact of biomass harvest and N fertilization on soil biogeochemistry and ecosystem yield with an ecosystem model of intermediate complexity that couples plant and soil C and N cycles. Two harvest schemes are modeled: continuous harvest at low intensity and periodic clear-cut harvest. Continuously-harvested systems sustain N harvest at steady-state under net mineralization conditions, which depends on the C:N ratio and respiration rate of decomposers. Further, linear stability analysis reveals steady-state harvest regimes are associated with stable foci, indicating oscillations in C and N pools that decay with time after harvest. Modeled ecosystems under periodic clear-cut harvest operate in a limit-cycle with net mineralization on average. However, when N limitation is strong, soil C–N cycling switches between net immobilization and net mineralization through time. The model predicts an optimal rotation length associated with a maximum sustainable yield (MSY) and minimum external N losses. Through non-linear plant–soil feedbacks triggered by harvest, strong N limitation promotes short periods of immobilization and mineral N retention, which alter the relation between MSY and N losses. Rotational systems use N more efficiently than continuous systems with equivalent biomass yield as immobilization protects mineral N from leaching losses. These results highlight dynamic soil C–N cycle responses to harvest strategy that influence a range of functional characteristics, including N retention, leaching, and biomass yield

Tutela giudiziale dei diritti fondamentali nel contesto europeo: il “dialogo” tra le corti nel disordine delle fonti

L’articolo ha ad oggetto il ruolo dei giudici e dell’interpretazione giudiziale nella ricerca di un “nuovo ordine” delle fonti del diritto in materia di diritti fondamentali nel contesto europeo. In primo luogo, mette in evidenza come l’indeterminatezza dei rinvii incrociati contenuti nella Costituzione italiana, nella Convenzione per la salvaguardia dei diritti umani e delle libertà fondamentali e nella Carta dei diritti fondamentali dell’Unione europea lasci spazio per prese di posizione alternative, e in competizione tra loro, in merito alla definizione di una gerarchia tra queste fonti del diritto. In secondo luogo, concentrandosi su come la questione è stata affrontata nella giurisprudenza della Corte costituzionale italiana, della Corte europea dei diritti umani e della Corte di giustizia dell’Unione europea, evidenzia alcuni dei principali limiti del cosiddetto “dialogo” tra le corti

Relazione tra modalità di risalita e cinetica di cristallizzazione nelle lave dell'Etna: un esempio di interpretazione cinetica della CSD

Obiettivo di questa tesi è la costruzione di un modello cinematico di risalita delle lave etnee basato sull’analisi congiunta delle CSD, dei dati sulle inclusioni magmatiche e dei calcoli geotermobarometrici. Un modello in grado di correlare le modalità di risalita con i processi ad essa associati, in particolare, il degassamento del fuso e i suoi effetti sulla cinetica di cristallizzazione registrati nelle strutture dei magmi eruttati. Per questo lavoro, sono state prese in esame diverse lave etnee relative al periodo 2011-2013. Su i vari campioni sono stati condotti studi di analisi d’immagine al fine di ricostruire le Crystal Size Distribution (CSD) dei plagioclasi. Inoltre, sono state eseguite analisi chimiche al SEM sui clinopirosseni, in modo da poter ottenere informazioni su condizioni P-T di cristallizzazione, utilizzando il geotermobarometro di Putirka (Putirka et al., 2003). Utilizzando dati di letterature sulle inclusioni magmatiche (Métrich et al., 2003), è stato possibile valutare il contenuto in H2O alle varie pressioni, ricostruendo così l’evoluzione del processo di essoluzione durante la risalita. La perdita di volatili, in particolare di H2O, tra tutti quello più abbondante, si riflette in una variazione della temperatura di liquidus, portando a un aumento della velocità di crescita dei cristalli e del loro tasso di nucleazione (Armienti et al., 2004); allo stesso modo, la variazione della temperatura del magma durante la risalita è strettamente connessa alle dinamiche della stessa, raffreddandosi con diversi tassi secondo la tipologia del moto di ascesa. Risulta quindi evidente come la cinematica di risalita controlli in maniera importante le leggi di crescita e nucleazione dei cristalli, portando a lave caratterizzate da diverse curve di CSD. Una legge di crescita per i plagioclasi è stata stimata attraverso la regressione di dati sperimentali presenti in bibliografia (Carroll et al., 2003). I tempi e la tipologia del moto di risalita sono le incognite di questo modello. Per questo motivo è necessario formulare delle ipotesi sulla tipologia del moto, vincolando questa al processo di cristallizzazione; in questo modo devono coincidere le tempistiche che permettono ai cristalli di raggiungere il numero e la taglia osservabile nelle rocce, con quelle del moto di ascesa del fuso verso la superficie. I tempi così ottenuti devono essere congrui con quelli che sono registrati nel contesto vulcanico reale: tempi di ritorno dell’attività esplosiva e del record sismico profondo, durata e frequenza dell’attività stromboliana antecedente le fasi più esplosive di fontane di lava. Abstract The aim of this thesis is to construct a kinematic model of the ascent typology of Etnean lavas based on the combined analysis of the CSDs, data on magmatic inclusions and geothermobarometric calculations. This model must be able to correlate the ascent modalities with the processes associated with them, in particular, melt degassing and its effects on the crystallization kinetics, recorded in the structures of erupted magmas. The lavas analyzed in this study refer to the eruptive period 2011-2013. By using of software for image analysis, it was possible to reconstruct the CSDs for plagioclase crystals. Furthermore, chemical analyzes were conducted on the pyroxene crystals, in order to obtain information about P and T of crystallization, through the use of Putirka’s geothermobarometer (Putirka et al., 2003). Using data on melt inclusion published by Métrich et al., 2003, it was possible to reconstruct the exsolution process during the ascent of magma, knowing the water content at different pressures. Water is the most abundant volatile component in magmas; its exsolution induces a dramatic change in the liquidus temperature, thus producing observable effects on the rates of nucleation and growth of minerals (Armienti et al., 1994). Similarly, the variation of magma temperature during its ascent, is closely linked to its dynamics, cooling with different rates according to the typology of ascent motion. For these reasons, the laws of nucleation and growth of crystals are controlled by the kinetics of the ascent, through the variation of the undercooling that can be linked to the shape of the CSDs. The law of Crystal growth rate has been calculated through the regression of literature experimental data (Carroll et al., 2003). Transport time and the typology of motion appear to be the unknown quantities of this model. For this reason it is necessary to make certain assumptions about the type of motion, linking this to the crystallization process; in this way, the timing which allow the crystals to reach the number and size observed in the rocks must coincide with those of the ascent of the melt to the surface. Thus, transport time obtained must be congruent with those that are recorded in the real volcanic environment: return periods of explosive activity and the deep seismic records, duration and frequency of Strombolian activity preceding the most explosive stages of lava fountains

La violenza contro le donne come questione (trans)culturale. Osservazioni sulla convenzione di Istanbul

Sebbene l’eguaglianza delle donne nei diritti fondamentali sia stata più volte riaffermata nel diritto internazionale, la violenza contro le donne è ancora diffusa in tutto il mondo. Concentrandosi sugli stati (multiculturali) dell’Europa di oggi, la Convenzione di Istanbul mostra grande consapevolezza politica e giuridica sia delle radici culturali di questo fenomeno sia della sua diffusione transculturale. Da qui l’importanza di un’analisi che sottolinei il contributo della Convenzione alla continua ricerca di politiche sempre più efficaci per combattere questa forma di violenza. Nondimeno, dal momento che il percorso si prospetta ancora lungo e difficile, è opportuno anche mettere in evidenza alcune possibili debolezze della Convenzione e alcuni ostacoli che possono ridimensionarne l’impatto giuridico, politico e sociale

Ecohydrological Controls on Grass and Shrub Above-ground Net Primary Productivity in a Seasonally Dry Climate

Seasonally dry, water‐limited regions are often co‐dominated by distinct herbaceous and woody plant communities with contrasting ecohydrological properties. We investigated the shape of the above‐ground net primary productivity (ANPP) response to annual precipitation (Pa) for adjacent grassland and shrubland ecosystems in Southern California, with the goal of understanding the role of these ecohydrological properties on ecosystem function. Our synthesis of observations and modelling demonstrates grassland and shrubland exhibit distinct ANPP‐Pa responses that correspond with characteristics of the long‐term Pa distribution and mean water balance fluxes. For annual grassland, no ANPP occurs below a ‘precipitation compensation point,’ where bare soil evaporation dominates the water balance, and ANPP saturates above the Pawhere deep percolation and runoff contribute to the modelled water balance. For shrubs, ANPP increases at a lower and relatively constant rate across the Pa gradient, while deep percolation and runoff account for a smaller fraction of the modelled water balance. We identify precipitation seasonality, root depth, and water stress sensitivity as the main ecosystem properties controlling these responses. Observed ANPP‐Paresponses correspond to notably different patterns of rain‐use efficiency (RUE). Grass RUE exceeds shrub RUE over a wide range of typical Pa values, whereas grasses and shrubs achieve a similar RUE in particularly dry or wet years. Inter‐annual precipitation variability, and the concomitant effect on ANPP, plays a critical role in maintaining the balance of grass and shrub cover and ecosystem‐scale productivity across this landscape

Framework for Event-based Semidistributed Modeling that Unifies the SCS-CN Method, VIC, PDM, and TOPMODEL

Hydrologists and engineers may choose from a range of semidistributed rainfall-runoff models such as VIC, PDM, and TOPMODEL, all of which predict runoff from a distribution of watershed properties. However, these models are not easily compared to event-based data and are missing ready-to-use analytical expressions that are analogous to the SCS-CN method. The SCS-CN method is an event-based model that describes the runoff response with a rainfall-runoff curve that is a function of the cumulative storm rainfall and antecedent wetness condition. Here we develop an event-based probabilistic storage framework and distill semidistributed models into analytical, event-based expressions for describing the rainfall-runoff response. The event-based versions called VICx, PDMx, and TOPMODELx also are extended with a spatial description of the runoff concept of ‘‘prethreshold’’ and ‘‘threshold-excess’’ runoff, which occur, respectively, before and after infiltration exceeds a storage capacity threshold. For total storm rainfall and antecedent wetness conditions, the resulting ready-to-use analytical expressions define the source areas (fraction of the watershed) that produce runoff by each mechanism. They also define the probability density function (PDF) representing the spatial variability of runoff depths that are cumulative values for the storm duration, and the average unit area runoff, which describes the so-called runoff curve. These new event-based semidistributed models and the traditional SCS-CN method are unified by the same general expression for the runoff curve. Since the general runoff curve may incorporate different model distributions, it may ease the way for relating such distributions to land use, climate, topography, ecology, geology, and other characteristics

Reply to Comment by Fred L. Ogden et al. on Beyond the SCS-CN Method: A Theoretical Framework for Spatially Lumped Rainfall-Runoff Response

Though Ogden et al. list several shortcomings of the original SCS-CN method, fit for purpose is a key consideration in hydrological modelling, as shown by the adoption of SCS-CN method in many design standards. The theoretical framework of Bartlett et al. [2016a] reveals a family of semidistributed models, of which the SCS-CN method is just one member. Other members include event-based versions of the Variable Infiltration Capacity (VIC) model and TOPMODEL. This general model allows us to move beyond the limitations of the original SCS-CN method under different rainfall-runoff mechanisms and distributions for soil and rainfall variability. Future research should link this general model approach to different hydrogeographic settings, in line with the call for action proposed by Ogden et al

Interlegality, Agency and Empowerment. A Different Take on the Feminism v. Multiculturalism Conundrum

By looking at the strategies of agency and empowerment enacted by women in contexts of interlegality, the article attempts to overcome the uncritical perpetuation of both cultural and gender stereotypes that still fuel the feminism v. multiculturalism debate, arguing that, on the one hand, interlegality creates spaces for the exercise of agency and, on the other hand, the exercise of agency unleashes the empowerment potential of interlegalit

Dissection of Neurons and Circuits Involved in Regulating Innate Behaviors, Movement and Higher Cognitive Functions in Mice

Elucidating the mechanisms through which brain circuits influence behavior is a fundamental tenet of Systems Neuroscience. Advancements in this field are critical to help us understand the inner workings of our brains, and eventually who we are as humans. Describing the physiologic functioning of neural circuits is also necessary to recognize their malfunctions, and to develop strategies to correct them. In many cases, however, alterations in the activity of brainwide circuits can be traced back to specific neuronal populations, and acting selectively upon these cells can restore the normal activity within the system, ultimately correcting the aberrant behavior. Thus, understanding how changes in gene expression and molecular profiles of neurons alter their function is critical to describe interneuronal dynamics within a circuit. During my graduate studies in the Friedman Laboratory at Rockefeller I had the opportunity to combine both Systems and Molecular-Cellular approaches to dissect the circuits and identify the neuronal populations involved in regulating behaviors along the broadest spectrum: from subconscious and innate behaviors (ie, control of energy homeostasis) all the way to the highest order functions (ie, anxiety and compulsive behaviors). To do so, I studied the interaction between cells, circuits and behavior in mice, an ideal model to test these conserved functions. This is because the mouse brain is evolutionarily close to the human brain, yet it is simpler and highly accessible to external manipulations with the molecular biology tools currently at our disposal. The main focus of my graduate work has been to investigate the mechanisms underlying movement control, and regulation of emotions and higher cognitive functions. This project responded to my interest, originated during my medical training, in finding commonalities and differences in neural circuits and functions between brain disorders traditionally classified as pertaining to the sphere of Neurology and Psychiatry. I thus focused on a neural network of nuclei deeply involved in these behaviors, known as the basal ganglia, and in particular on the role of the Subthalamic Nucleus (STN) in Parkinson’s Disease and Obsessive-Compulsive Disorder. I identified previously undescribed subpopulations of STN neurons, and tested their role in mediating motor, emotional and cognitive functions in mice, both in normal and pathologic state. This part of my graduate work is detailed in Chapter 1 to 6. The data I present here have important implications for the physiology and pathophysiology of movement and psychiatric disorders, with the potential for enabling further translational studies. In addition to my main study, I was fascinated by the work conducted in the Friedman Laboratory to elucidate the metabolic and nervous mechanisms that regulate energy balance in the body. I therefore collaborated with a postdoctoral fellow in the laboratory and adopted the same experimental approaches to dissect a neural circuit involved in the maintenance of body temperature in mice. The anterior hypothalamus has been the main brain area associated with thermoregulation since the 1950s. With our work, however, we found that a brainstem region known as the Dorsal Raphe Nucleus (DRN), and particularly a subpopulation of DRN neurons, can also respond selectively and powerfully to changes in external stimuli to maintain a constant body temperature. We also showed that this effect is achieved by inducing changes in both thermogenesis and locomotor activity, and mediated via projections to the anterior hypothalamus and to other brain areas known to be involved in thermoregulation. This part of my graduate work is detailed in the Appendix section. Taken together, these experiments reveal a circuit configuration that allows for the robust control of an innate homeostatic response

Climate, Not Conflict, Explains Extreme Middle East Dust Storm

The recent dust storm in the Middle East (September 2015) was publicized in the media as a sign of an impending ‘Dust Bowl.’ Its severity, demonstrated by extreme aerosol optical depth in the atmosphere in the 99th percentile compared to historical data, was attributed to the ongoing regional conflict. However, surface meteorological and remote sensing data, as well as regional climate model simulations, support an alternative hypothesis: the historically unprecedented aridity played a more prominent role, as evidenced by unusual climatic and meteorological conditions prior to and during the storm. Remotely sensed normalized difference vegetation index demonstrates that vegetation cover was high in 2015 relative to the prior drought and conflict periods, suggesting that agricultural activity was not diminished during that year, thus negating the media narrative. Instead, meteorological simulations using the Weather Research and Forecasting (WRF) model show that the storm was associated with a cyclone and ‘Shamal’ winds, typical for dust storm generation in this region, that were immediately followed by an unusual wind reversal at low levels that spread dust west to the Mediterranean Coast. These unusual meteorological conditions were aided by a significant reduction in the critical shear stress due to extreme dry and hot conditions, thereby enhancing dust availability for erosion during this storm. Concluding, unusual aridity, combined with unique synoptic weather patterns, enhanced dust emission and westward long-range transport across the region, thus generating the extreme storm