Usefulness of Social Sensing Using Text Mining of Tweets for Detection of Autumn Phenology

Can social sensing detect the spatio-temporal variability of autumn phenology? We analyzed data published on the Twitter social media website through the text mining of non-geotagged tweets regarding a forested, mountainous region in Japan. We were able to map the spatial characteristic of tweets regarding peak leaf coloring along an altitudinal gradient and found that text mining of tweets is a useful approach to the in situ collection of autumn phenology information at multiple locations over a broad spatial scale. Potential uncertainties in this approach were examined and compared to other online research sources and methods, including Google Trends and information on widely available websites and live camera images. Finally, we suggest ways to reduce the uncertainties identified within our approach and to create better integration between text mining of tweets and other online research data sources and methods.

Global and regional ecological boundaries drive abrupt changes in avian frugivory interactions

Species interactions can propagate disturbances across space, though ecological and biogeographic boundaries may limit this spread. We tested whether large-scale ecological boundaries (ecoregions and biomes) and human disturbance gradients increase dissimilarity among ecological networks, while accounting for background spatial and elevational effects and differences in network sampling. We assessed network dissimilarity patterns over a broad spatial scale, using 196 quantitative avian frugivory networks (encompassing 1,496 plant and 1,003 bird species) distributed across 67 ecoregions and 11 biomes. Dissimilarity in species and interactions, but not in network structure, increased significantly across ecoregion and biome boundaries and along human disturbance gradients. Our findings suggest that ecological boundaries contribute to maintaining the world's biodiversity of interactions and mitigating the propagation of disturbances at large spatial scales.

A data-driven evaluation of post-fire landslide susceptibility

Wildfires change the hydrologic and geomorphic response of watersheds, which has been associated with cascading hazards that include shallow landslides and debris flows. This study evaluates post-wildfire landslide trigger characteristics by comparing precipitation preceding landslides at both burned and unburned locations. Landslide events are selected from the NASA Global Landslide Catalog (GLC) to facilitate regional inter-comparison. Fire and precipitation histories for each site are established using MODIS global burned area and CHIRPS precipitation data, respectively. Analysis of normalized seven-day accumulated precipitation for sites across all regions shows that, globally, landslides at burned sites are preceded by less precipitation than landslides without antecedent burn events. This supports the hypothesis that fire increases rainfall-driven landslide hazards. An analysis of the seasonality of landslides at burned and unburned locations shows that landslide-triggering storms in burned locations tend to exhibit different seasonality from other rainfall-triggered landslides, with a variety of seasonal shifts ranging from approximately six months in the Pacific Northwest of North America to one week in the Himalaya region. Overall, this manuscript offers an exploration of regional differences in the characteristics of rainfall-triggered landslides over a broad spatial scale and encompassing a variety of climates, geographies, and burn conditions.

Biomass and height of Ascophyllum nodosum after two decades of continuous commercial harvesting in eastern Canada

With the increasing demand for seaweed resources worldwide, management must ensure that the harvest of wild seaweed stocks is sustainable. We evaluate the impact of over 25 years of commercial harvesting of Ascophyllum nodosum in eastern Canada by comparing the biomass and height of the seaweed in the late 1990s to the late 2010s over a broad spatial scale spanning the provinces of Nova Scotia and New Brunswick. There has been no significant decrease in the biomass of A. nodosum in either province, and biomass has increased in some regions of New Brunswick during that period. The average height of A. nodosum has decreased by 7.8 cm in Nova Scotia while it increased by 13.8 cm in New Brunswick. Biomass of A. nodosum in unharvested sectors was 7% higher than that in harvested sectors while height of A. nodosum in unharvested sectors in New Brunswick is similar to the values observed in harvested sectors. Over the same period, water temperature has increased in both provinces and, in recent years, has at times exceeded the optimal growing temperature for A. nodosum within bays in Nova Scotia. We conclude that the current management and harvest of A. nodosum in eastern Canada are sustainable and maintain the biomass and height of A. nodosum beds but that control sites are necessary to offer adequate comparisons as environmental conditions are changing.

Assessing the quantitative impact of ecosystem shifts on human societies

A wide range of ecosystems have been reported to show abrupt and drastic shifts in their states. Such shifts in ecosystem states, typically known as regime shifts, are hardly predictable and not readily reversible once they have taken place, and can have considerable impacts on human societies that are dependent on those ecosystems. Nevertheless, earlier studies have rarely quantified the consequences of ecosystem shifts for human societies, instead focusing largely on identifying the occurrence of shifts, understanding drivers and mechanisms, and developing early warning signals for forecasting. We address this knowledge gap by searching for scientific evidence on the quantitative impacts of ecosystem shifts on human societies. Based on a set of pre-defined search criteria we identified a total of 92 papers that discussed particular ecosystem shifts and associated impacts. The number of papers reporting ecosystem shifts and associated impacts has considerably increased over the past 20 years, indicating a recent rise in the interest in the issue among scientific communities. The 92 papers reported state shifts in a wide range of ecosystems, with marine ecosystem shifts reported most frequently (in 22 papers), followed by shifts in wetland (18 papers) and forest (10 papers) ecosystems. Climate change was by far the most frequently reported driver of ecosystem shifts (reported in 32 papers), followed by land use change (12 papers) and nutrient inputs (nine papers). Only 17 (18%) out of the 92 papers described the quantitative consequences of ecosystem shifts for human societies. Estimated economic consequences ranged from 5 million US dollars per year relating to eutrophication of Swedish coastal waters, to costs of 200 billion US dollars linked to macro-algal green tides along the Qingdao coast. We found that our knowledge of quantitative impacts of ecosystem shifts on human societies is still severely limited, especially in terms of risks to human health and survival and, at a broad spatial scale, where multiple ecosystem shifts could interact to exacerbate the extent or severity of their impacts.

Mate-searching context of prey influences the predator–prey space race

Predation risk is a strong driver of prey distribution and movement. However, fitness-influencing behaviours, such as mating, can alter risk and influence predator–prey space-use dynamics. In tree crickets, Oecanthus henryi , mate searching involves acoustic signalling by immobile males and phonotactic movement by females. Space-use patterns in tree crickets relative to their primary predators, green lynx spiders ( Peucetia viridans ), should therefore depend on their current mate-searching state; whether males are calling or non-calling and whether females are phonotactic or non-phonotactic. We first measured the degree of spatial anchoring of crickets to specific bushes in the field and determined whether that influenced the probability of broad-scale spatial overlap with spiders. In the absence of spiders, all crickets, independent of sex or male calling status, were found to be spatially anchored to specific types of bushes and not uniformly distributed on the landscape. At the broad spatial scale, spiders were more likely to be found on bushes with female crickets and, to a lesser degree, calling male crickets. At a finer spatial scale within a bush, movement strategies of crickets not only varied depending on the presence or absence of a spider, but also on their current mate-searching state. Phonotactic females showed clear predator avoidance, whereas calling and non-calling males moved towards the spider instead of away, similar to predator inspection behaviour seen in many taxa. As the strongly selected sex, males are more likely to undertake risky mate-searching activities, which includes inspection of predator positions. Overall, we found that all crickets were predictably anchored at the landscape scale, but their sex and mate-seeking behaviour influenced the degree of overlap with predators and their antipredator movement strategies. Reproductive strategies within a prey species, therefore, can alter predator–prey space race at multiple spatial scales.

Evolutionary time drives global tetrapod diversity

Global variation in species richness is widely recognized, but the explanation for what drives it continues to be debated. Previous efforts have focused on a subset of potential drivers, including evolutionary rate, evolutionary time (maximum clade age of species restricted to a region), dispersal (migration from one region to another), ecological factors and climatic stability. However, no study has evaluated these competing hypotheses simultaneously at a broad spatial scale. Here, we examine their relative contribution in determining the richness of the most comprehensive dataset of tetrapods to our knowledge (84% of the described species), distinguishing between the direct influences of evolutionary rate, evolutionary time and dispersal, and the indirect influences of ecological factors and climatic stability through their effect on direct factors. We found that evolutionary time exerted a primary influence on species richness, with evolutionary rate being of secondary importance. By contrast, dispersal did not significantly affect richness patterns. Ecological and climatic stability factors influenced species richness indirectly by modifying evolutionary time (i.e. persistence time) and rate. Overall, our findings suggest that global heterogeneity in tetrapod richness is explained primarily by the length of time species have had to diversify.

Competition and coexistence in sympatric skunks

Ecological niches of three species of skunks (Mephitidae: Conepatus leuconotus, Mephitis mephitis, M. macroura) in and near their overlap zone in the American Southwest were studied to determine if competition may be limiting distribution of these species. A species distribution model developed in MaxEnt was used to identify suitable habitat for each species, from which contact zones for each species pair were identified. Principal components derived from habitat and climate variables inside and outside of contact zones for each species, and between species pairs within the contact zone were then compared. Species differed in environmental space inside and outside of contact zones, but species pairs did not differ within contact zones, indicating no evidence of competitive exclusion, and possible niche convergence at a broad spatial scale

A dasymetric method to apportion tornado casualty counts spatially

This paper describes a dasymetric technique to spatially apportion casualty counts from tornado events in the U.S. Storm Prediction Center's database. Apportionment is performed with respect to the proportion of damage path area and to the underlying population density. The method is illustrated with raster grids on tornadoes occurring between 1955 and 2015 within the most tornado-prone region of the United States. Validation of the results using county- and grid-level data reveals strong correlation between dasymetric estimated and location-specific counts. On a broad spatial scale the method provides a better estimate of where casualties have occurred than counting the number of casualty-producing tornadoes. Case studies using the 1974 Xenia, OH and the 1994 Piedmont, AL tornadoes highlight limitations of the method and indicate that results will be improved with more precise tornado path information. Future work that includes socioeconomic variables (demographics, ethnicity, poverty and housing stock/value) might allow populations to be profiled with regards to vulnerability.

Fine-Scale Genetic Structure and Reproductive Biology of the Blueberry Pathogen Monilinia vaccinii-corymbosi

The fungus Monilinia vaccinii-corymbosi, a pathogen of Vaccinium spp., requires asexual and sexual spore production to complete its life cycle. A recent study found population structuring of M. vaccinii-corymbosi over a broad spatial scale in the United States. In this study, we examined fine-scale genetic structuring, temporal dynamics, and reproductive biology within a 125-by-132-m blueberry plot from 2010 to 2012. In total, 395 isolates of M. vaccinii-corymbosi were sampled from infected shoots and fruit to examine their multilocus haplotype (MLH) using microsatellite markers. The MLH of 190 single-ascospore isolates from 21 apothecia was also determined. Little to no genetic differentiation and unrestricted gene flow were detected among four sampled time points and between infected tissue types. Discriminant analysis of principal components suggested genetic structuring within the field, with at least K = 3 genetically distinct clusters maintained over four sampled time points. Single-ascospore progeny from eight apothecia had identical MLH and at least two distinct MLH were detected from 13 apothecia. Tests for linkage disequilibrium suggested that genetically diverse ascospore progeny were the product of recombination. This study supports the idea that the fine-scale dynamics of M. vaccinii-corymbosi may be complex, with genetic structuring, inbreeding, and outcrossing detected in the study area.