Spatial patterns and functional redundancies in a changing boreal lake landscape

Global transformations extend beyond local habitats; therefore, larger-scale approaches are needed to assess community-level responses and resilience to unfolding environmental changes. Using long-term data (1996-2011), we evaluated spatial patterns and functional redundancies in the littoral invertebrate communities of 85 Swedish lakes, with the objective of assessing their potential resilience to environmental change at regional scales (that is, spatial resilience). Multivariate spatial modeling was used to differentiate groups of invertebrate species exhibiting spatial patterns in composition and abundance (that is, deterministic species) from those lacking spatial patterns (that is, stochastic species). We then determined the functional feeding attributes of the deterministic and stochastic invertebrate species, to infer resilience. Between one and three distinct spatial patterns in invertebrate composition and abundance were identified in approximately one-third of the species; the remainder were stochastic. We observed substantial differences in metrics between deterministic and stochastic species. Functional richness and diversity decreased over time in the deterministic group, suggesting a loss of resilience in regional invertebrate communities. However, taxon richness and redundancy increased monotonically in the stochastic group, indicating the capacity of regional invertebrate communities to adapt to change. Our results suggest that a refined picture of spatial resilience emerges if patterns of both the deterministic and stochastic species are accounted for. Spatially extensive monitoring may help increase our mechanistic understanding of community-level responses and resilience to regional environmental change, insights that are critical for developing management and conservation agendas in this current period of rapid environmental transformation

1,4-Dimethyl­piperazin-1-ium 3-hy­droxy-2-naphtho­ate

The reaction of 1,4-dimethyl­piperazine and 3-hy­droxy-2-naphthoic acid gives the title 1:1 salt, C6H15N2 +·C11H7O3 −, with a singly protonated piperazinium cation. In the crystal, a single N—H⋯O hydrogen bond links the cations and anions into discrete pairs and the aromatic anions stack along the crystallographic a-axis direction. This results in layers of cations and anions alternating along the crystallographic c-axis direction. An intra­molecular O—H⋯O hydrogen bond is also present

Optimal scales to observe habitat dynamics: A coral reef example

A new technique to estimate the characteristic length scales (CLSs) of real ecological systems provides an objective means to identify the optimal scale(s) of observation to best detect underlying dynamical trends. Application of the technique to natural systems has focused on identifying appropriate scales to measure the dynamics of species as descriptors of community and ecosystem dynamics. However, ecosystem monitoring is often based not on assessing single species, but on species assemblages, functional groups, or habitat types. We asked whether the concept of CLSs based on dynamic interactions among species could be extended to examine interactions among habitat types and thus to identify optimal scales for observing habitat dynamics. A time series of three spatial maps of benthic habitats on a Caribbean coral reef was constructed from aerial photographs, Compact Airborne Spectrographic Imager (CASI) images, and IKONOS satellite images, providing the short time sequence required for this technique. We estimated the CLS based on the dynamics of three distinct habitat types: dense stands of seagrass, sparse stands of seagrass, and Montastrea patch reefs. Despite notable differences in the areal extent of and relative change in these habitats over the 21-year observation period, analyses based on each habitat type indicated a similar CLS of similar to 300 m. We interpret the consistency of CLSs among habitats to indicate that the dynamics of the three habitat types are linked. The results are encouraging, and they indicate that CLS techniques can be used to identify the appropriate scale at which to monitor ecosystem trends on the basis of the dynamics of only one of a disparate suite of habitat types

Panarchy and management of lake ecosystems

A key challenge of the Anthropocene is to confront the dynamic complexity of systems of people and nature to guide robust interventions and adaptations across spatiotemporal scales. Panarchy, a concept rooted in resilience theory, accounts for this complexity, having at its core multiscale organization, interconnectedness of scales, and dynamic system structure at each scale. Despite the increasing use of panarchy in sustainability research, quantitative tests of its premises are scarce, particularly as they pertain to management consequences in ecosystems. In this study we compared the physicochemical environment of managed (limed) and minimally disturbed reference lakes and used time series modeling and correlation analyses to test the premises of panarchy theory: (1) that both lake types show dynamic structure at multiple temporal scales, (2) that this structure differs between lake types due to liming interacting with the natural disturbance regime of lakes, and (3) that liming manifests across temporal scales due to cross-scale connectivity. Hypotheses 1 and 3 were verified whereas support for hypothesis 2 was ambiguous. The literature suggests that liming is a “command-and-control” management form that fails to foster self-organization manifested in lakes returning to pre-liming conditions once management is ceased. In this context, our results suggest that redundance of liming footprints across scales, a feature contributing to resilience, in the physicochemical environment alone may not be enough to create a self-organizing limed lake regime. Further research studying the broader biophysical lake environment, including ecological communities of pelagic and benthic habitats, will contribute to a better understanding of managed lake panarchies. Such insight may further our knowledge of ecosystem management in general and of limed lakes in particular

The Distribution of High and Low Redshift Type Ia Supernovae

The distribution of high redshift Type Ia supernovae (SNe Ia) with respect to projected distance from the center of the host galaxy is studied and compared to the distribution of local SNe. The distribution of high-z SNe Ia is found to be similar to the local sample of SNe Ia discovered with CCDs, but different than the sample discovered photographically. This is shown to be due to the Shaw effect. These results have implications for the use of SNe Ia to determine cosmological parameters if the local sample of supernovae used to calibrate the light curve decline relationships is drawn from a sample discovered photographically. A K-S test shows that the probability that the high redshift SNe of the Supernova Cosmology Project are drawn from the same distribution as the low redshift calibrators of Riess et al. is 0.1%. This is a potential problem because photographically discovered SNe are preferentially discovered farther away from the galaxy nucleus, where SNe show a lower scatter in absolute magnitude, and are on average 0.3 magnitudes fainter than SNe located closer to the center of their host galaxy. This raises questions about whether or not the calibration SNe sample the full range of parameters potentially present in high redshift SNe Ia. The limited data available suggest that the calibration process is adequate; however, it would be preferable if high redshift SNe and the low redshift SNe used to calibrate them were drawn from the same sample, as subtle differences may be important. Data are also presented which suggest that the seeming anti-Malmquist trend noticed by Tammann et al.(1996, 1998) for SNe Ia in galaxies with Cepheid distances may be due to the location of the SNe in their host galaxies.Comment: 16 pages, 2 figures Accepted for publication in the Astrophysical Journa

Spatial Ecology of the Coachwhip, Masticophis flagellum (Squamata: Colubridae), in Eastern Texas

We radio-tracked nine Masticophis flagellum (Coachwhips) to determine home range, habitat use, and movements in eastern Texas from April to October 2000. Home ranges of Coachwhips contained more oak savanna macrohabitat than early-successional pine plantation or forested seep, based on the availability of these three macrohabitats in the study area. Likewise, within their individual home ranges, Coachwhips used oak savanna more than the other two macrohabitats, based on availability. An analysis of microhabitat use revealed that, relative to random sites within their home range, Coachwhips were found at sites with fewer pine trees and more herbaceous vegetation taller than 30 cm. Results of the two analyses, macrohabitat and microhabitat, were consistent: oak savannas contained relatively few pine trees but much herbaceous vegetation taller than 30 cm. Coachwhips made frequent long-distance moves, which resulted in large home ranges. Core activity areas, however, were small. These core activity areas were always within the oak savanna macrohabitat. Long movements, large home ranges, and small core activity areas likely were a result of the preferred oak savanna macrohabitat being patchily distributed in the landscape