Invasive cordgrass (Spartina spp.) in south‐eastern Australia induces island formation,salt marsh development,and carbon storage

Invasive vegetation species can lead to major changes in the geomorphology of coastal systems. Within temperate estuaries in the southern hemisphere, especially Australia and New Zealand, the cordgrass Spartina spp. has become established. These species are highly invasive, and their prolific growth leads to the development of supratidal environments in formerly intertidal and subtidal environments. Here, we quantified the impact of Spartina invasion on the geomorphology and sequestration capacity of carbon in the sediments of Anderson Inlet, Victoria, Australia. Spartina was first introduced to the area in the 1930s to aid in land reclamation and control coastal erosion associated with coastal development. We found that Spartina now dominates the intertidal areas of the Inlet and promotes accretion (18 mm/year) causing the formation of over 108 ha of supratidal islands over the past 100 years. These newly formed islands are calculated to potentially contain over 5.5 million tonnes of CO₂ equivalent carbon. Future management of the inlet and other Spartina‐dominated environments within Australian presents a dilemma for resource managers; on the one hand, Spartina is highly invasive and can outcompete native tidal marshes, thereby warranting its eradication, but on the other hand it is likely more resilient to rising sea levels and has the potential for carbon sequestration. Whether or not the potential advantages outweigh the significant habitat change that is anticipated, any management strategies will likely require additional research into costs and benefits of all ecosystem services provided by Spartina including in relation to nutrient cycling, shoreline stabilisation, and biodiversity as well as in response to the longevity of carbon found within the sediments.     

Multiphase flow simulation through porous media with explicitly resolved fractures

Accurate simulation of multiphase flow in fractured porous media remains a challenge. An important problem is the representation of the discontinuous or near discontinuous behaviour of saturation in real geological formations. In the classical continuum approach, a refined mesh is required at the interface between fracture and porous media to capture the steep gradients in saturation and saturation‐dependent transport properties. This dramatically increases the computational load when large numbers of fractures are present in the numerical model. A discontinuous finite element method is reported here to model flow in fractured porous media. The governing multiphase porous media flow equations are solved in the adaptive mesh computational fluid dynamics code IC‐FERST on unstructured meshes. The method is based on a mixed control volume – discontinuous finite element formulation. This is combined with the P_N+1DG‐P_NDG element pair, which has discontinuous (order N+1) representation for velocity and discontinuous (order N) representation for pressure. A number of test cases are used to evaluate the method's ability to model fracture flow. The first is used to verify the performance of the element pair on structured and unstructured meshes of different resolution. Multiphase flow is then modelled in a range of idealised and simple fracture patterns. Solutions with sharp saturation fronts and computational economy in terms of mesh size are illustrated.     

No Trinity: The tripartite relations between Agudat Yisrael,the Mizrahi movement,and the Zionist Organization

This article investigates the dynamics between the two major Orthodox political movements of the twentieth century – the religious Zionist movement Mizrahi and its non-Zionist opponent Agudat Yisrael – in the context of their tripartite relationship with the Zionist Organization. Due to its increased involvement in Palestinian affairs, the Agudah entered negotiations with the Zionists in the mid-1920s. These negotiations and the possibility of cooperation between Agudat Yisrael and the Zionist Organization threatened the position of the religious Zionists within the ZO. The resulting competition between the two Orthodox groups led to the refinement of party platforms and the crystallization of independent political camps.     

Obedient children and reckless rebels: Jabotinsky's youth politics and the case for authoritarian leadership, 1931–1933

This article traces the pivotal role that ideas about “youth” and “generationhood” played in Vladimir Jabotinsky's political strategy as leader of the Union of Revisionist Zionists and its youth movement, Brit Yosef Trumpeldor (Betar). During the leadership struggle within the movement between 1931 and 1933, Jabotinsky believed that he could draw upon debates sweeping across Europe about the nature of youth, their role in politics, and the challenges of “generational conflict” in order to convince his followers that his increasingly authoritarian behavior was the only mode of leadership available to Zionist leaders in the 1930s. The article demonstrates that Jabotinsky's deliberately ambiguous and provocative constructions of “youth” and “generationhood” within the movement's party literature and in articles addressed to the Polish Jewish public, as well as the innovative ways in which he delimited “youth” from “adult” in his movement's regulations, allowed him to further embrace authoritarian measures within the movement without publicly abandoning his claim to be a firm proponent of democracy.     

Latent trajectory models for space‐time analysis: An application in deciphering spatial panel data

This article introduces latent trajectory models (LTMs), an approach often employed in social sciences to handle longitudinal data, to the arena of GIScience, particularly space‐time analysis. Using the space‐time data collected at county level for the whole United States through webpage search on the keyword “climate change,” we show that LTMs, when combined with eigenvector filtering of spatial dependence in data, are very useful in unveiling temporal trends hidden in such data: the webpage‐data derived popularity measure for climate change has been increasing from December 2011 to March 2013, but the increase rate has been slowing down. In addition, LTMs help reveal potential mechanisms behind observed space‐time trajectories through linking the webpage‐data derived popularity measure about climate change to a set of socio‐demographic covariates. Our analysis shows that controlling for population density, greater drought exposure, higher percent of people who are 16 years old or above, and higher household income are positively predictive of the trajectory slopes. Higher percentages of Republicans and number of hot days in summer are negatively related to the trajectory slopes. Implications of these results are examined, concluding with consideration of the potential utility of LTMs in space‐time analysis and more generally in GIScience.