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We studied a cohort-based, long-lived species to determine whether favorable periods that promote regeneration are driven by local, regional, or global-scale factors. Limited demographic data exist for the keystone species Carnegiea gigantea over its range. We obtained a data set collected for 12,232 plants over an area of more than 11 km2 at a restricted military zone, located far from any other studied population. We developed the establishment pattern for the species over the last 200 yr and compared population growth trends with those for other sites and with global-scale volcanism, which has been previously linked to the regeneration of the species. This population was significantly related to the two closer sites, suggesting a regional influence in regeneration and cohort establishment. Other eastern sites like ours also exhibited a regeneration peak in the 1920s. This population was not significantly related to volcanic eruptions, as has been documented elsewhere, though this may be due to subsequent mortality at the site, which would have effectively erased the record of establishment in past periods. Unlike past work, our study goes beyond a single population. We synthesized data from other known populations in order to produce, for the first time, a coherent picture of the patterns of regeneration over much of the species' range. Large-scale climatic (e.g., unusually rainy periods) and geologic (global-scale volcanism) events promote the establishment of cohorts during the same time periods historically, though to differing extents in different populations: hot, western populations have particularly large cohorts in response to volcanism, while more eastern sites may have observable cohorts during known wetter periods. Thus, these different large-scale phenomena appear to be of varying significance in a population on the basis of the population's location and associated environment. This provides insight into global climate change impacts on the species, whose keystone status will ultimately affect the success of and changes in the entire biome. [ABSTRACT FROM AUTHOR]

This paper attempts to establish linkages between growth by a keystone wetland plant, Panicum hemitomon Schultes, and the independent and interactive effect of nutrient and hydrologic regime to inform management and rehabilitation of thick-mat floating marsh (TMFM). To do so a manipulative glasshouse experiment employing created TMFM similar to that under consideration for field trials and two levels each of N, P and hydrology was conducted. P. hemitomon grew vigorously under saturated (flooding level with the surface of the mat) when compared to inundated (+15 cm flooding) hydrologic conditions, and under enriched (50 g m−2 year−1) when compared to non-enriched (25 g m−2 year−1) N. Further, and as inferred from net CO2 assimilation, shoot biomass and rhizome biomass and length, N-enriched conditions seemed to lessen inundation stress. For all variables the interaction between N and hydrology was non-significant and there was no observable effect of P. We were unable to infer root or mat buoyancy from root specific gravity measurements but it was evident at harvest that saturation or minimal flooding is required for vigorous root and rhizome growth. This study provides insight to the notion that decreased mat buoyancy (and increased flooding level) resulting from sediment deposition associated with Mississippi River diversions could adversely affect TMFM sustainability, but more clearly demonstrates the need to maintain saturated hydrologic conditions for achieving the type of root and rhizome growth we feel is required for TMFM rehabilitation. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the range-wide population structure and phylogeography of thuriferous juniper (Juniperus thurifera L.), a species with a highly disjunct distribution in the western Mediterranean. We genotyped a total of 327 individuals from 20 populations using amplified fragment length polymorphisms (AFLP). Different analyses such as principal co-ordinate analysis (PCoA), nonmetric multidimensional scaling of F ST distances among populations, unweighted pair group method with arithmetic mean (UPGMA), and Bayesian clustering revealed that the Strait of Gibraltar acted as an efficient barrier against gene flow between the Moroccan and European populations for a very long time, and consequently support that the Moroccan populations should be recognised as a distinct subspecies (J. thurifera L. subsp. africana (Maire) Romo and Boratyńsky). The Algerian population was genetically more closely related to the European than to the Moroccan ones, probably due to dispersal events from Europe to Algeria. With respect to the mainland European populations, our data are not conclusive to reject any of the two following hypotheses: (1) the Iberian Peninsula was subdivided into different gene pools, and was the source for the colonisation of the Pyrenees and the Alps; and (2) the pattern we see today is partly the result of immigration into the Iberian Peninsula, e.g. from the Alps. Finally, the Corsican population was closely related genetically to two northern Iberian populations most probably due to relatively recent long-distance dispersal. [Copyright &y& Elsevier]

The article presents a study on the dynamics of sedimentary structures at the reach scales using a field approach. The aims of the study are to determine the processes of sedimentary structures development from a manipulated bed surface and to show the impact of keystones in the evolution of the sedimentary structures by monitoring the displacement of individual tagged particles. The author states that the initial manipulations of the bed headed to a more fragmented surface in the experimental section. Sedimentary structures, however, developed very fast, with an equilibrium bed surface developing only two sediment transport events of low magnitude discharge.

The influence of keystone consumers on community structure is frequently context-dependent; the same species plays a central organising role in some situations, but not others. On Christmas Island, in the Indian Ocean, a single species of omnivorous land crab, Gecarcoidea natalis, dominates the forest floor across intact rainforest. We hypothesised that this consumer plays a key role in regulating seedling recruitment and in controlling litter dynamics on the island, independent of the type of vegetation in which it occurred. To test this hypothesis, we conducted crab exclusion experiments in two forest types on the island and followed the dynamics of seedling recruitment and litter processing for six years. To determine if these effects were likely to be general across the island, we compared land crab densities and seedling abundance and diversity at ten sites across island rainforest. Surveys across island rainforest showed that seedlings of species susceptible to predation by land crabs are consistently rare. Abundance and diversity of these species were negatively correlated to red crab abundance. Although red land crabs may be important determinants of seedling recruitment to the overstorey, differences in overstorey and seedling composition at the sites suggests that recruitment of vulnerable trees still occurs at a temporal scale exceeding that of this study. These “windows” of recruitment may be related to infrequent events that reduce the effects of land crabs. Our results suggest that unlike the context dependence of most keystone consumers in continental systems, a single consumer, the red land crab, consistently controls the dynamics of seedling recruitment across this island rainforest. [ABSTRACT FROM AUTHOR]

This paper describes the development and study of a disposable and inexpensive microfluidic chip, fabricated from poly(dimethylsiloxane) (PDMS) incorporating conventional chromatographic reversed-phase silica particles (C18) without the use of frits, permanent physical barriers, tapers, or restrictors. The packing of C18 modified silica particles into the microfluidic channels is made possible by the hydrophobic nature and excellent elasticity of PDMS. Keystone-, clamping-, and anchor-effects provide the stability and the compactness of the packing and attenuated wall-effects were observed. [ABSTRACT FROM AUTHOR]

1. Ecosystems have higher-order emerging properties that can affect the conservation of species. We identify some of these properties in order to facilitate a better understanding of them. 2. Nonlinear, indirect effects of food web interactions among species can produce counterintuitive changes in populations. 3. Species differ in their roles and linkages with other species in the system. These roles are a property of the system. Such differences in roles influence how we conserve individual species. 4. Ecosystems operate at a multitude of interacting spatial and temporal scales, which together structure the system and affect the dynamics of individual populations. 5. Disturbance also structures an ecosystem, producing both long-term slow changes and sudden shifts in ecosystem dynamics. 6. Ecosystems therefore can have multiple states, determined both by disturbance regimes and biotic interactions. Conservation should recognize a possible multiplicity of natural states while avoiding aberrant (human-induced) states. 7. Ecosystem processes are influenced by the composition of the biota they contain. Disturbances to the biota can distort processes and functions, which in turn can endanger individual species. 8. The goal of ecosystem conservation is the long-term persistence of the biota in the system. There are two paradigms: community-based conservation (CBC) and protected area conservation. Both have their advantages but neither is sufficient to protect the biota on its own. 9. CBC is required to conserve the majority of the world's biota not included in protected areas. However, current CBC methods favour a few idiosyncratic species, distort the species complex, and ignore the majority. More comprehensive methods are required for this approach to meet the goal of ecosystem conservation. 10. Protected areas are essential to conserve species unable to coexist with humans. They also function as ecological baselines to monitor the effects of humans on their own ecosystems. 11. However, protected areas suffer from loss of habitat through attrition of critical areas. Thus, renewal (addition) of habitat is required in order to achieve the long-term persistence of biota in functioning ecosystems. Identification of minimum habitat areas and restoration of ecosystems become two major priorities for future research. [ABSTRACT FROM AUTHOR]

Phenological transects were employed to assess monthly leaf, flower, unripe fruit and ripe fruit abundance for a total of 1732 individual plants within five tropical forest habitats at the ‘Lago Caiman Research Camp’, Noel Kempff Mercado National Park, northeastern Santa Cruz Department, Bolivia. Fruit surveys along trails were conducted concomitantly to assess fruit availability for the resident terrestrial frugivore community. The results of the two methodologies are compared and discussed with respect to wildlife and forest management in the region. Phenological transects revealed that Cerrado forest, tall forest, low vine forest, Sartenejal (swamp) forest, and pied mont (premontane) forest, showed seasonal variations in flower, unripe fruit and ripe fruit abundance, however, the broad temporal patterns were significantly different across habitats. Seasonal variation in overall foliage abundance was only marked for Cerrado forest. Ripe fruit production within the study site was not significantly different across months, with different habitats peaking asynchronously in abundance. From a frugivory perspective, overall ripe fleshy fruit abundance also varied considerably between habitats, and again showed asynchronous peaks in habitat production. However, both methodologies revealed the early dry season (June–July) as a period of ripe fleshy fruit scarcity throughout the study area. This period represents a resource ‘bottleneck’ for the resident frugivore community and phenological results allowed the identification of a number of keystone fruit resources for the region. Furthermore, fruit resources which are super-abundant in the early–mid wet season (November–February) might also be considered keystone resources for the region, given that they are available in an otherwise fruit scarce forest. The dynamic spatial patterning of fruit availability at Lago Caiman suggests that certain habitats might be considered keystone habitats, since they provide the majority of fruit resources on a seasonal basis. Finally, the potential of phenological information in tropical forest management plans is discussed and underlined by the observation that rainfall in itself fails to predict fruit availability in the dominant habitats at Lago Caiman. [Copyright &y& Elsevier]

1. Focal species (i.e. indicators, keystones, umbrellas, and flagships) have been advocated for the management and conservation of natural environments. 2. The assumption has been that the presence or abundance of a focal species is a means to understanding the composition and/or state of the more complex community. 3. We review the characteristics of focal species, and evaluate their appropriateness and utility judged against conservation objectives. 4. It appears that indicator species (of both composition and condition) may be of greatest general utility, and that several types of focal species may exhibit useful indicator properties. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Presents information on a study to examine the consequences of extreme spatial and temporal variation in the recruitment of a prey species supporting keystone and diffuse predation. Information on the keystone predator's hypothesis; Methodology used to conduct the study; Results of the study; Discussion based on the results of the study.

Florence Cathedral continues to yield surprises, and it is not always necessary to dig for them. A detail as small and seemingly insignificant as a keystone is here revealed as evidence of a trecento project for a set of minor lanterns. Ironically, but for good reasons, this scheme was abandoned by the very architects who in all likelihood actually crafted the keystone, Filippo Brunelleschi and Lorenzo Ghiberti. The detail is full of implications about Early Renaissance architectural practice, and it would be the first documented, completed architectural "work" involving Brunelleschi. [ABSTRACT FROM AUTHOR]

The article discusses the importance of creativity and bricolage in ancient Renaissance architecture. According to the author, architectural collections are composed of sculpture, low reliefs and columns which displayed the appropriation of antiquity. It is expressed that the reassemblages of these structures made direct reference to their origins. The arrangement of pediments, historical friezes, keystones, pilasters, frames and balustrades functioned as quotations of ancient temples, thermae, villas and palaces.

CALIFORNIA REACHED a landmark achievement last year by hitting a keystone renewable energy target just before Christmas, raising hopes of a prosperous new year for investors, project developers and manufacturers. [ABSTRACT FROM AUTHOR]

Conflict between humans and large predators is a longstanding challenge that can present negative consequences for humans and wildlife. Sharks have a global distribution and are considered to pose a potential threat to humans; concurrently many shark species are themselves threatened. Developing strategies for coexistence between humans and this keystone group is imperative. We assess blimp surveillance as a technique to simply and effectively reduce shark encounters at ocean beaches and determine the social acceptance of this technique as compared to an established mitigation strategy—shark meshing. We demonstrate the suitability of blimps for risk mitigation, with detection probabilities of shark analogues by professional lifeguards of 0.93 in ideal swimming conditions. Social surveys indicate strong social acceptance of blimps and preference for non-lethal shark mitigation. We show that continuous aerial surveillance can provide a measurable reduction in risk from sharks, improving beach safety and facilitating coexistence between people and wildlife. [ABSTRACT FROM AUTHOR]

The article discusses the planned transformation of Penn Museum keystone galleries into showcases of collections that tell stories of mankind's past as of spring 2016. Topics covered include the current "The Golden Age of King Midas," and the renovation and innovation for the Ancient Middle East, Asian, and Egyptian gallery spaces. Also noted is the galleries' expected engagement of visitors of all ages.

Recent advances in complex networks research allow to take a closer look at various ecological interactions that involve both plants and animals at the level of ecosystems. Especially mutualistic interactions (eg. pollination) play a crucial role in generating and sustaining biodiversity of terrestrial ecosystems. Many authors regard them as "architecture of biodiversity" because usually they connect dozens or even hundreds of species, forming large and complex networks of reciprocally beneficial interactions. The structure of such networks is highly heterogeneous and asymmetric: most of the species are rather weakly connected, while some of taxa develop much stronger relationships. Based on our studies in semi-natural habitats in NE Poland we will demonstrate how new mathematical tools allow to analyse the pollination network structure and can be farther applied to indicate "keystone" species which may be important in determining the stability of the studied ecosystems. [ABSTRACT FROM AUTHOR]