Christopher J. Anderson

ExScal: elements of an extreme scale wireless sensor network

Project ExScal (for extreme scale) fielded a 1000+ node wireless sensor network and a 200+ node peer-to-peer ad hoc network of 802.11 devices in a 13km by 300m remote area in Florida, USA during December 2004. In comparison with previous deployments, the ExScal application is relatively complex and its networks are the largest ones of either type fielded to date. In this paper, we overview the key requirements of ExScal, the corresponding design of the hardware/software platform and application, and some results of our experiments.

Creating Wetlands: Primary Succession, Water Quality Changes, and Self-Design over 15 Years

The succession of vegetation, soil development, water quality changes, and carbon and nitrogen dynamics are summarized in this article for a pair of 1-hectare flow-through-created riverine wetlands for their first 15 years. Wetland plant richness increased from 13 originally planted species to 116 species overall after 15 years, with most of the increase occurring in the first 5 years. The planted wetland had a higher plant community diversity index for 15 years, whereas the unplanted wetland was more productive. Wetland soils turned hydric within a few years; soil organic carbon doubled in 10 years and almost tripled in 15 years. Nutrient removal was similar in the two wetlands in most years, with a trend of decreased removal over 15 years for phosphorus. Denitrification accounted for a small percentage of the nitrogen reduction in the wetlands. The wetlands were effective carbon sinks with retention rates of 1800–2700 kilograms of carbon per hectare per year, higher than in comparable reference wetlands and more commonly studied boreal peatlands. Methane emission rates are low enough to create little concern that the wetlands are net sources of climate change radiative forcing. Planting appears to have influenced carbon accumulation, methane emissions, and macrophyte community diversity.

Sediment, Carbon, and Nutrient Accumulation at Two 10-Year-Old Created Riverine Marshes

Two 1-ha riverine wetlands at the Olentangy Wetland Research Park in Columbus, Ohio, USA were constructed in 1993 with a nearly identical geomorphology and have maintained an identical hydrology since their creation. The only initial difference was that one wetland was planted with native macrophytes in 1994 while the other was not. Sediment and nutrient accumulation was evaluated in May 2004, ten years after the wetlands were created. Higher mean sediment accumulation was detected in the deeper open water (OW) zones of both wetlands (6.1 ±0.6 and 7.3 ±0.5 kg m−2 yr−1) than in the emergent (EM) vegetation zones (3.7 ±0.2 and 3.9 ±0.3 kg m−2 yr−1). Directional spatial structure associated with sediment accumulation was detected in both wetlands and was attributed to the greater accumulation in the OW zones and the gradual decrease in accumulation from inflow to outflow. Despite several years of markedly higher productivity in Wetland 2, this wetland showed no evidence of greater organic C accumulation; however, the dense Typha established during those years may have elicited greater deposition and reduced re-suspension of sediment in the OW zones. Large accumulations of Ca (235 ±23 and 235 ±15 kg m−2 yr−1) and inorganic C (71.6 ±6.9 and 70.3 ±4.8 g m−2 yr−1) in the OW zones of both wetlands suggest that CaCO3 deposition has remained a critical process where alga productivity has been highest. Annual rates of sediment and nutrient accumulation for each wetland were lower than those calculated in previous years and typically fall between ranges seen for newly created wetlands and natural wetlands.

Effect of Pulsing on Macrophyte Productivity and Nutrient Uptake: A Wetland Mesocosm Experiment

Abstract A study was conducted to evaluate the effect of a pulsing hydrology on the productivity and nutrient uptake of an herbaceous riverine wetland. Pulsing effects were evaluated using 20 0.9-m2 wetland mesocosms: 10 planted with Schoenoplectus tabernaemontani (C.C. Gmel) Palla and the other 10 planted with Typha angustifolia L. For each species, half the mesocosms were subjected to a 3-mo pulsing regime while the others were subjected to steady-flow conditions. Hydrology parameters were selected to approximate a pulsing experiment being carried out concurrently at two 1-ha wetlands at the research site. Typha wetlands were significantly more productive than Schoenoplectus wetlands; however no significant differences in productivity or morphology were observed between pulsed or steady-flow wetlands among species groups. No significant differences in nutrient concentrations, uptake or uptake efficiency were detected among species groups either, however hydrology did influence plant tissue N:P ratios. For all wetland mesocosms, the mean N:P ratio was 9.2 ± 0.6 for steady flow wetlands and 11.7 ± 0.5 for pulsed, suggesting that the steady flow wetlands were more N limited than pulsed wetlands. The potential applications and limitations of applying these results to the 1-ha wetlands study are discussed.

Project exscal

Project ExScal (for Extreme Scale) fielded a 1000+ node wireless sensor network and a 200+ node ad hoc network of 802.11 devices in a 1.3km by 300m remote area in Florida during December 2004. In several respects, these networks are likely the largest deployed networks of either type to date. We overview here the key requirements of the project, describe briefly how they were met and experimentally tested, and provide a pointer to our experimental results.

Changes in Wetland Forest Structure, Basal Growth, and Composition across a Tidal Gradient

Abstract Because of their proximity to oceanic waters, freshwater tidal forests are susceptible to impacts from future climate change and sea level rise. These wetlands are historically understudied and we conducted our study to improve the understanding of structural changes in forested wetlands as they become tidally influenced. Using 20 forested stands across a tidal gradient on the lower Apalachicola River, Florida we examined changes in forest structure (tree density, size classes), basal growth, sapling/shrub cover and richness, understory cover/richness, and coarse woody debris. Tidal wetlands had greater tree (>2.5 cm DBH) density compared to nontidal forests (1446 ± 159 and 962 ± 100 stems ha−1, respectively) and more small trees (2.5 to 5.0 cm DBH) (699 and 359 stems ha−1, respectively). Over a 3 y period (2007 to 2010), basal area increment ranged from −0.07 to 0.30 m2 ha−1 y−1 for tidal wetlands and 0.07 to 0.55 m2 ha−1 y−1 for nontidal wetlands. Both forests experienced tree mortality during the study that influenced basal area. Tidal wetland tree mortality appeared to result from saltwater intrusion while several nontidal forest plots were affected by downed trees during a winter wind storm. Mean sapling/shrub (<2.5 cm DBH) density and richness in tidal forests were more than twice that estimated for nontidal forests. Mean herbaceous cover in tidal wetlands (72 ± 4%) was significantly higher than nontidal forests (19 ± 4%) and dominated by perennial herbaceous plants as opposed to nontidal wetlands that were often dominated by tree seedlings. Mean, large, coarse, woody, debris biomass (>7.62 cm diameter) was significantly lower in tidal wetlands compared to nontidal wetlands. Results demonstrated that riparian forests can have large and sudden shifts in stand structure and species composition related to tidal influences where rivers approach the coast.

Classification of organisms: living and fossil

The classification advanced herein provides a framework to which any organism can be readily placed and offers comprehensive coverage of the entire biological spectrum. The viruses are incorporated as a kingdom of organisms and a rationale advanced for a 6-kingdom system. Many seldom-classified fossil organisms are included, with a significant number of them classified at an advanced level. Individual phyla are recognized for the fossil genera Tribrachidium, Amiskwia, Dinomischus, Anomalocaris, Tullimonstrum, Hallucigenia, Opabinia and Pikaia. Other seldom-recognized phyla include viruses, conularids, loriciferans, tentaculites, hyoliths, scleritophores, myzostomans, acorn worms, conodonts, monoblastozoans and volborthellids. The notion that failures (geologically) cannot be phyla is rejected. A system of kingdom-related and rank-related suffixes is incorporated with the flexible opportunity, if deemed necessary, to advance or reduce taxa by re-suffixing. Other features of the complete classification of Anderson (Classification of Organisms: Living and Fossil, Golden Crowns Press, Lancaster, OH, 1992) include the elimination of duplicate taxa, incorporation of geologic ranges and number of species for many groups, and extensive usage of common names, which are completely indexed.

Erratum to: Sediment, carbon, and nutrient accumulations at two 10-year-old created riverine marshes

The following corrections should be made for the article by Christopher J. Anderson and William J. Mitsch in Vol. 26, No. 3, pp. 779–792, titled: ‘‘Sediment, carbon, and nutrient accumulations at two 10-year-old created riverine marshes’’: In the sentence starting on the twelfth line of the Abstract (p. 779, ‘‘Large accumulations...’’), the reported accumulation of Ca should be changed from ‘‘kg’’to‘‘g’’toread:235623and235615 g m yr. In the first sentence of the Results (p. 783, ‘‘Mean bulk density...), the reported bulk density of the EM zone sediment in Wetland 2 should be changed from ‘‘0.57 60.05 g cm’’ to ‘‘0.50 60.03 g cm’’. On p. 784 and 785, legend text for Figures 4 and 5 were inadvertently switched. Under the figure on p. 784 (second column) the legend should read: ‘‘Figure 4. Correlogram (Moran’s I over mean distance) for sediment accumulation in a) Wetland 1 and b) Wetland 2 for isotropic and anisotropic (0u, 45u, and 135u) analyses’’. Under the figure on p. 785 the legend should read: ‘‘Figure 5. Spatial distribution maps of sediment accumulations for Wetland 1 and 2. Maps were generated by ordinary point kriging using anisotropic variogram models (0u and 135u, respectively). Degree bearings provided for reference’’. WETLANDS, Vol. 27, No. 3, September 2007, p. 774 ’ 2007, The Society of Wetland Scientists

Floristic Composition of Alabama Piedmont Floodplains across a Gradient of Stream Channel Incision

Abstract Stream channel incision in the Piedmont of the southeastern US has resulted in a loss of stream and floodplain functions. Reduced flood frequency and lowered water tables typify incised low-order streams of the region. The objective of this study was to determine if a quantifiable shift in riparian vegetation community structure exists along a gradient of channel incision. Stream channel incision was described using bank height ratio (BHR), defined as the ratio of streambank height to bankfull depth. Ten low-order streams in the Alabama Piedmont were selected across a gradient of BHR values (1.0–5.2). Stream incision is strongly correlated with a shift of community type in the ground flora stratum, from wetland-adapted species at low degrees of incision to plants typical of upland settings at incised sites. Based on Nonmetric Multidimensional Scaling (NMDS) ordinations, functional composition of the ground flora layer was significantly related to median groundwater depth and BHR. These results suggest strong linkages between channel incision, subsequent lowered water table levels and decreased soil moisture, and herbaceous/ground flora composition in floodplains of the Alabama Piedmont.