A Rigorous Observation Model for the Risley Prism-Based Livox Mid-40 Lidar Sensor.

Modern lidar sensors are continuing to decrease in size, weight, and cost, but the demand for fast, abundant, and high-accuracy lidar observations is only increasing. The Livox Mid-40 lidar sensor was designed for use within sense-and-avoid navigation systems for autonomous vehicles, but has also found adoption within aerial mapping systems. In order to characterize the overall quality of the point clouds from the Mid-40 sensor and enable sensor calibration, a rigorous model of the sensor's raw observations is needed. This paper presents the development of an angular observation model for the Mid-40 sensor, and its application within an extended Kalman filter that uses the sensor's data to estimate the model's operating parameters, systematic errors, and the instantaneous prism rotation angles for the Risley prism optical steering mechanism. The analysis suggests that the Mid-40's angular observations are more accurate than the specifications provided by the manufacturer. Additionally, it is shown that the prism rotation angles can be used within a planar constrained least-squares adjustment to theoretically improve the accuracy of the angular observations of the Mid-40 sensor.

Evaluating the data quality of iNaturalist termite records.

Citizen science (CS) contributes to the knowledge about species distributions, which is a critical foundation in the studies of invasive species, biological conservation, and response to climatic change. In this study, we assessed the value of CS for termites worldwide. First, we compared the abundance and species diversity of geo-tagged termite records in iNaturalist to that of the University of Florida termite collection (UFTC) and the Global Biodiversity Information Facility (GBIF). Second, we quantified how the combination of these data sources affected the number of genera that satisfy data requirements for ecological niche modeling. Third, we assessed the taxonomic correctness of iNaturalist termite records in the Americas at the genus and family level through expert review based on photo identification. Results showed that iNaturalist records were less abundant than those in the UFTC and in GBIF, although they complemented the latter two in selected world regions. A combination of GBIF and the UFTC led to a significant increase in the number of termite genera satisfying the abundance criterion for niche modeling compared to either of those two sources alone, whereas adding iNaturalist observations as a third source only had a moderate effect on the number of termite genera satisfying that criterion. Although research grade observations in iNaturalist require a community-supported and agreed upon identification (ID) below the family taxonomic rank, our results indicated that iNaturalist data do not exhibit a higher taxonomic classification accuracy when they are designated research grade. This means that non-research grade observations can be used to more completely map the presence of termite locations in certain geographic locations without significantly jeopardizing data quality. We concluded that CS termite observation records can, to some extent, complement expert termite collections in terms of geographic coverage and species diversity. Based on recent data contribution patterns in CS data, the role of CS termite contributions is expected to grow significantly in the near future.

Individual Movement Strategies Revealed through Novel Clustering of Emergent Movement Patterns.

Understanding movement is critical in several disciplines but analysis methods often neglect key information by adopting each location as sampling unit, rather than each individual. We introduce a novel statistical method that, by focusing on individuals, enables better identification of temporal dynamics of connectivity, traits of individuals that explain emergent movement patterns, and sites that play a critical role in connecting subpopulations. We apply this method to two examples that span movement networks that vary considerably in size and questions: movements of an endangered raptor, the snail kite (Rostrhamus sociabilis plumbeus), and human movement in Florida inferred from Twitter. For snail kites, our method reveals substantial differences in movement strategies for different bird cohorts and temporal changes in connectivity driven by the invasion of an exotic food resource, illustrating the challenge of identifying critical connectivity sites for conservation in the presence of global change. For human movement, our method is able to reliably determine the origin of Florida visitors and identify distinct movement patterns within Florida for visitors from different places, providing near real-time information on the spatial and temporal patterns of tourists. These results emphasize the need to integrate individual variation to generate new insights when modeling movement data.

Dispersal Flights of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae).

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a pest of major economic concern. This termite is particularly known for its tendency to establish populations in nonendemic areas via maritime vessels as well as human-aided transport of infested materials. The natural spread of this species after new introductions occurs in part by dispersal flights originating from mature colonies. Dispersal flight activity is also the primary variable for the evaluation of area-wide management programs. Few studies exist describing the dynamics and distribution of a typical dispersal flight for this species. The present study used data collected by mark-recapture of C. formosanus alates over 12 individual evenings of dispersal flights in the New Orleans French Quarter. In this study, we found that for one selected flight dispersal location, which was not affected by a high density of trap locations nearby, alates flew on average 621 m from their parent colony. A new record of a 1,300-m dispersal flight was recorded. Spatial analysis showed that neither wind nor light affected the direction of flight, which may, however, be attributed to scarce light and wind measurements in the study region.

Predicting the geographical distribution of two invasive termite species from occurrence data.

Predicting the potential habitat of species under both current and future climate change scenarios is crucial for monitoring invasive species and understanding a species' response to different environmental conditions. Frequently, the only data available on a species is the location of its occurrence (presence-only data). Using occurrence records only, two models were used to predict the geographical distribution of two destructive invasive termite species, Coptotermes gestroi (Wasmann) and Coptotermes formosanus Shiraki. The first model uses a Bayesian linear logistic regression approach adjusted for presence-only data while the second one is the widely used maximum entropy approach (Maxent). Results show that the predicted distributions of both C. gestroi and C. formosanus are strongly linked to urban development. The impact of future scenarios such as climate warming and population growth on the biotic distribution of both termite species was also assessed. Future climate warming seems to affect their projected probability of presence to a lesser extent than population growth. The Bayesian logistic approach outperformed Maxent consistently in all models according to evaluation criteria such as model sensitivity and ecological realism. The importance of further studies for an explicit treatment of residual spatial autocorrelation and a more comprehensive comparison between both statistical approaches is suggested.

Simulating the spread of an invasive termite in an urban environment using a stochastic individual-based model.

Invasive termites are destructive insect pests that cause billions of dollars in property damage every year. Termite species can be transported overseas by maritime vessels. However, only if the climatic conditions are suitable will the introduced species flourish. Models predicting the areas of infestation following initial introduction of an invasive species could help regulatory agencies develop successful early detection, quarantine, or eradication efforts. At present, no model has been developed to estimate the geographic spread of a termite infestation from a set of surveyed locations. In the current study, we used actual field data as a starting point, and relevant information on termite species to develop a spatially-explicit stochastic individual-based simulation to predict areas potentially infested by an invasive termite, Nasutitermes corniger (Motschulsky), in Dania Beach, FL. The Monte Carlo technique is used to assess outcome uncertainty. A set of model realizations describing potential areas of infestation were considered in a sensitivity analysis, which showed that the model results had greatest sensitivity to number of alates released from nest, alate survival, maximum pheromone attraction distance between heterosexual pairs, and mean flight distance. Results showed that the areas predicted as infested in all simulation runs of a baseline model cover the spatial extent of all locations recently discovered. The model presented in this study could be applied to any invasive termite species after proper calibration of parameters. The simulation herein can be used by regulatory authorities to define most probable quarantine and survey zones.

Identification of environmental, managerial, and sociodemographic correlates of hiker volume on the Florida National Scenic Trail.

PURPOSE: The purpose of this study was to identify the association of environmental, managerial, and sociodemographic variables with hiker volume on the Florida National Scenic Trail. DESIGN: Monthly hiker count data from 43 count stations along the Florida National Scenic Trail were used. For each station the characteristics of the built and natural environment as well as sociodemographic variables were computed within a Geographic Information System based on census, land use, and land cover data, together with managerial data. SETTING: Counts were performed on access points of the Florida National Scenic Trail located between the panhandle area in the northwest and the Everglades in the south. SUBJECTS: A total of 34,734 hikers were counted across the 43 stations over 12-month periods for years 2003-2004 and 2008-2009. MEASURES: Hiker volume was measured through infrared counters and registration cards at trail access points. ANALYSIS: A negative binomial regression with monthly hiker counts as response variable. RESULTS: Positive associations with hiker volume were observed for (population density per hectare) 2 (ß â€Š=  .207, p < .02), residential areas (ß â€Š=  .041, p < .0003), household income between $25,000 and $49,999 (ß â€Š=  .266, p < .0001), household income between $50,000 and $99,999 (ß â€Š=  .135, p < .0001), open water (ß â€Š=  .135, p < .0001), and station kilometers north (ß â€Š=  .003, p < .0001). Negative associations with hiker volume were observed for age <18 (ß â€Š=  -.305, p < .0001) and presence of trail fees (ß â€Š=  -.583, p < .0001). Positive and negative associations were observed for different categories in categorical variables including prominent vegetation type (p < .0001), trail management agency (p < .0001), and month (p < .0001). CONCLUSIONS: The correlates should be considered for the design, planning, and promotion of hiking trails in publicly managed areas to increase hiker volume.

Spatial association of marine dockage with land-borne infestations of invasive termites (Isoptera: Rhinotermitidae: Coptotermes) in urban south Florida.

Marine vessels have been implicated in the anthropogenic dispersal of invasive termites for the past 500 yr. It has long been suspected that two invasive termites, the Formosan subterranean termite, Coptotermes formosanus Shiraki, and Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae), were introduced to and dispersed throughout South Florida by sailboats and yachts. We compared the distances between 190 terrestrial point records for Formosan subterranean termite, 177 records for C. gestroi, and random locations with the nearest marine dockage by using spatial analysis. Results show that the median distance to nearest docks associated with C. gestroi is significantly smaller than for the random points. Results also reveal that the median distance to nearest docks associated with Formosan subterranean termite is significantly smaller than for the random points. These results support the hypothesis that C. gestroi and Formosan subterranean termite are significantly closer to potential infested boat locations, i.e., marine docks, than random points in these urban areas. The results of our study suggest yet another source of aggregation in the context of exotic species, namely, hubs for pleasure boating.