Vegetation patterns and their underlying processes: where are we now?

This Special Feature of the Journal of Vegetation Science contains ten contributions from the 56th Symposium of the International Association for Vegetation Science (IAVS), which was held in Tartu, Estonia, 26–30 Jun 2013, and focused on processes underlying vegetation patterns. These contributions give an overview of recent advances in vegetation science, with topics ranging from the introduction of new methods and ideas to comprehensive analysis of vegetation patterns on a global scale. The focus of these Special Feature contributions indicates that vegetation science is becoming more global, more complex and more interdisciplinary. It is likely that progress in methods and accumulation of data have led vegetation science into a ‘new era of discovery’.     

Mechanochemical Synthesis: A Tool to Tune Cation Site Disorder and Ionic Transport Properties of Li3MCl6 (M = Y,Er) Superionic Conductors

The lithium‐conducting, rare‐earth halides, Li₃MX₆ (M = Y, Er; X = Cl, Br), have garnered significantly rising interest recently, as they have been reported to have oxidative stability and high ionic conductivities. However, while a multitude of materials exhibit a superionic conductivity close to 1 mS cm^?1, the exact design strategies to further improve the ionic transport properties have not been established yet. Here, the influence of the employed synthesis method of mechanochemical milling, compared to subsequent crystallization routines as well as classic solid‐state syntheses on the structure and resulting transport behavior of Li₃ErCl₆ and Li₃YCl₆ are explored. Using a combination of X‐ray diffraction, pair distribution function analysis, density functional theory, and impedance spectroscopy, insights into the average and local structural features that influence the underlying transport are provided. The existence of a cation defect within the structure in which Er/Y are disordered to a new position strongly benefits the transport properties. A synthetically tuned, increasing degree of this disordering leads to a decreasing activation energy and increasing ionic conductivity. This work sheds light on the possible synthesis strategies and helps to systematically understand and further improve the properties of this class of materials.     

To compete or not to compete: an experimental study of interactions between plant species with contrasting root behaviour

Game-theoretic models predict that plants with root systems that avoid belowground competition will be displaced by plants that overproduce roots in substrate shared with competitors. Despite this, both types of root response to neighbours have been documented. We used two co-occurring clonal species (Glechoma hederacea and Fragaria vesca) with contrasting root responses to neighbours (avoidance of competition and contesting of resources, respectively) to examine whether functional variation in other traits affected the success of each rooting strategy, leading to a different outcome from that predicted on the basis of root behaviour alone. Vegetative propagation rates, morphology and biomass allocation patterns were examined when each species was challenged with competition from physically separate ramets with either the same rooting strategy (intraclonal competition) or the contrasting rooting strategy (interspecific competition). Contrary to the predictions of game-theoretic models, the species that exhibits avoidance of root competition (Glechoma) was not competitively inferior to the species that does not (Fragaria). Glechoma achieved greater total mass in the interspecific treatment than in the intraclonal treatment. However, Fragaria did not experience more intense competition from Glechoma than it did in the intraclonal treatment. Strong interference between the two species appeared to be avoided because Glechoma invested preferentially in rapid exploitation of unoccupied space, whereas Fragaria invested in increasing the competitive ability and local persistence of established ramets. Our results suggest that interspecific trade-offs between traits related to competitive ability and resource exploitation can allow coexistence of species with contrasting rooting behaviours. Full assessment of the adaptive value of different root responses to neighbours therefore requires concurrent consideration of the combined effects of a wide array of functional traits.     

Autogenic succession in boreal mires — A review

The main features of autogenic bog development are discussed. Using extensive literature the changes in vegetation, surface topography, soil environment and hydrology are characterized. Oligotrophy and low pH seem to be the most important factors directing bog succession. The decrease in decomposition rates correlates with increase of the content of dissolved oxygen in the soil water. Due to substantial changes in local environment bog succession should be considered first of all as an ecosystem process. In comparison with mineral land communities bog succession is characterized by more deterministic development. Both successional convergence and divergence are observed. In every case the concrete character of bog dynamics depends on the spatial and temporal scales of investigation.