McCune, Jenny L.

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    A new record of Stylophorum diphyllum (Michx.) Nutt. in Canada: a case study of the value and limitations of building species distribution models for very rare plants
    (BioOne, 2019) McCune, Jenny L.
    Stylophorum diphyllum (Michx.) Nutt. is an endangered plant of rich floodplain forests in southern Ontario, Canada. Prior to 2015 there were only four known populations in Ontario. I built a species distribution model (SDM) based on the known occurrences, and tested it by surveying 156 forest sites that varied in their predicted suitability. An indicator species analysis showed that sites predicted to be suitable had significantly higher frequency and abundance of common species usually associated with S. diphyllum, demonstrating the ability of the SDM to pinpoint similar habitat, although none of these sites contained S. diphyllum. The most important predictors used by the SDM to determine habitat suitability were growing season precipitation, surficial geology, and soil texture. I discovered a new population of S. diphyllum more than 50 km north of the known populations, at one of the sites not predicted to be suitable. This demonstrates a clear example of SDM overfitting, which may occur when models are built based on few, spatially limited occurrence records. Nonetheless, the key environmental predictors remained the same in an updated SDM including the new record. Stylophorum diphyllum provides a case study of both the value and the limitations of using SDMs to predict suitable habitat for very rare and geographically restricted plants, and the need for more rare plant surveys even in human-dominated landscapes.
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    Are we accurately estimating the potential role of pollution in the decline of species at risk in Canada?
    (Canadian Science Publishing, 2019) McCune, Jenny L.; Colla, Sheila R.; Coristine, Laura E.; Davy, Christina M.; Flockhart, D. T. Tyler; Schuster, Richard; Orihel, Diane M.
    Pollution is a pervasive, albeit often invisible, threat to biodiversity in Canada. Currently, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) relies on expert opinion to assess the scope (i.e., the proportion of a species’ population that may be affected) of pollution to species at risk. Here, we describe a spatially explicit, quantitative method for assessing the scope of pollution as a threat to species at risk in Canada. Using this method, we quantified the geographic co-occurrence of 488 terrestrial and freshwater species and pollution sources and determined that, on average, 57% of the mapped occurrences of each species at risk co-occurred with at least one pollution source. Furthermore, we found a weak correlation between the scope of the threat of pollution as assessed by COSEWIC expert panels and the geographic overlap of species occurrences and pollution sources that we determined with our quantitative method. Experts frequently identified scope of pollution as absent or negligible even for species with extensive co-occurrence with pollution sources, especially vascular plants. Clearly, a quantitative approach is needed to make accurate estimates of the scope of pollution as a threat to species at risk in Canada.
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    Assessing public comitment to endangered species protection: a Canadian case study
    (Canadian Science Publishing, 2017) McCune, Jenny L.; Carlsson, Anja M.; Colla, Sheila; Davy, Christina; Favaro, Brett; Ford, Adam T.; Fraser, Kevin C.; Martins, Eduardo G.
    Preventing the extinction of species will require limiting human activities in key areas, but it is unclear to what extent the public is committed to these limits and the associated costs. We commissioned an online survey of 1000 Canadians and asked them if it is important to prevent the extinction of wild species in Canada. We used specific scenarios illustrating the need for limits to personal activities, private property rights, and industrial development to further test their support. The respondents were strongly committed to species conservation in principle (89% agree), including the need to limit industrial development (80% agree). There was less support for limiting private property rights (63% agree), and more uncertainty when scenarios suggested potential loss of property rights and industry-based jobs. This highlights the high level of public concern regarding the economic impacts of preventing extinctions, and the need for more programs to encourage voluntary stewardship of endangered species on private land. Opinion polls that measure public support for conservation without acknowledging the concessions required may result in overly optimistic estimates of the level of support. Most Canadians in our sample supported endangered species conservation even when the necessity of limiting human activities was explicitly stated.
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    Comparing the effect of landscape context on vascular plant and bryophyte communities in a human-dominated landscape
    (Wiley, 2020) McCune, Jenny L.; Frendo, Christina J.; Ramadan, Mohammed; Baldwin, Lyn K.
    Aims: It is important to understand the effect of landscape context on biological communities to predict how biodiversity will be affected on human-dominated land-scapes. While many studies have tested the effects of landscape context on the spe-cies richness and composition of vascular plants, few have compared the responses of vascular plants and bryophytes on the same landscape. We sampled non-epiphytic bryophytes and vascular plants in 184 plots to test whether three landscape context factors measured four years or four decades previously could predict bryophyte or vascular plant species richness and composition after accounting for local factors.Location: Temperate forests and oak savannahs, Vancouver Island, British Columbia, Canada.Methods: We used model selection and comparisons to test the effects of surround-ing road density, total amount of forest, and distance to the nearest forest edge on species richness, species richness of non-disturbance-associated species, and com-munity composition after controlling for important local predictors including sub-strate availability and topography.Results: The species richness of non-disturbance-associated vascular plants was lower in plots with greater surrounding historical road density, and perennial stayer bryophyte richness declined with increasing historical road density and lower histori-cal forest amount, suggesting a potential extinction debt. Landscape context signifi-cantly affected total species richness and community composition of vascular plants, but not bryophytes.Conclusion: While bryophytes appear to be less sensitive overall to landscape con-text than vascular plants, disturbance-intolerant perennial stayer bryophytes may decline in the future in response to the increased road density and loss of forest cover that has occurred over the past four decades.
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    Conserving plant species at risk in Canada: land tenure, threats, and representation in federal programs
    (Canadian Science Publishing, 2020) McCune, Jenny L.; Morrison, Peter D. S.
    Fully 37% of species listed under Canada’s Species at Risk Act (SARA) are plants or lichens. The law does not automatically protect species on private land, and it is unknown how many at-risk plants grow mainly on private land. We analyzed official status reports and related documents for 234 plant species at risk to determine land tenure and evaluated differences in threats and changes in status. We also assessed how well plants were represented in two federal programs: the Natural Areas Conservation Program (NACP) and the Habitat Stewardship Program (HSP). Of SARA-listed plant species, 35% have the majority of their known populations on private land while <10% occur mostly on federal land. Species growing mainly on private land were no more or less likely to decline in status over time compared with others. Plant species at risk were less likely than other taxonomic groups to be found on land protected under the NACP. The proportion of HSP projects targeting plants is well below the expected proportion based on the number of listed species. We recommend that policy-makers promote and prioritize actions to increase the representation of plant species in federally funded programs, especially on private lands.
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    Context-dependent interactions and the regulation of species richness in freshwater fish
    (Nature Publishing Group, 2018) MacDougall, Andrew S.; Harvey, Eric; McCune, Jenny L.; Nilsson, Karin A.; Bennett, Joseph; Firn, Jennifer; Bartley, Timothy; Grace, James B.; Kelly, Jocelyn; Tunney, Tyler D.; McMeans, Bailey; Matsuzaki, Shin-Ichiro S.; Kadoya, Taku; Esch, Ellen; Cazelles, Kevin; Lester, Nigel; McCann, Kevin S.
    Species richness is regulated by a complex network of scale-dependent processes. This complexity can obscure the influence of limiting species interactions, making it difficult to determine if abiotic or biotic drivers are more predominant regulators of richness. Using integrative modeling of freshwater fish richness from 721 lakes along an 11o latitudinal gradient, we find negative interactions to be a relatively minor independent predictor of species richness in lakes despite the widespread presence of predators. Instead, interaction effects, when detectable among major functional groups and 231 species pairs, were strong, often positive, but contextually dependent on environment. These results are consistent with the idea that negative interactions internally structure lake communities but do not consistently ‘scale-up’ to regulate richness independently of the environment. The importance of environment for interaction outcomes and its role in the regulation of species richness highlights the potential sensitivity of fish communities to the environmental changes affecting lakes globally.
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    Do traits of plant species predict the efficacy of species distribution models for finding new occurences?
    (Wiley, 2020) McCune, Jenny L.; Rosner-Katz, Hanna; Bennett, Joseph R.; Schuster, Richard; Kharouba, Heather M.
    Species distribution models (SDMs) are used to test ecological theory and to direct targeted surveys for species of conservation concern. Several studies have tested for an influence of species traits on the predictive accuracy of SDMs. However, most used the same set of environmental predictors for all species and/or did not use truly independent data to test SDM accuracy. We built eight SDMs for each of 24 plant species of conservation concern, varying the environmental predictors included in each SDM version. We then measured the accuracy of each SDM using independent presence and absence data to calculate area under the receiver operating characteristic curve (AUC) and true positive rate (TPR). We used generalized linear mixed models to test for a relationship between species traits and SDM accuracy, while accounting for variation in SDM performance that might be introduced by different predictor sets. All traits affected one or both SDM accuracy measures. Species with lighter seeds, animal-dispersed seeds, and a higher density of occurrences had higher AUC and TPR than other species, all else being equal. Long-lived woody species had higher AUC than herbaceous species, but lower TPR. These results support the hypothesis that the strength of species–environment correlations is affected by characteristics of species or their geographic distributions. However, because each species has multiple traits, and because AUC and TPR can be affected differently, there is no straightforward way to determine a priori which species will yield useful SDMs based on their traits. Most species yielded at least one useful SDM. Therefore, it is worthwhile to build and test SDMs for the purpose of finding new populations of plant species of conservation concern, regardless of these species’ traits.
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    Habitat characteristics of Botrychium species in the Castle Region, Alberta, Canada
    (Brigham Young University, 2024) Chisholm, Trinitas; McCune, Jenny L.
    ABSTRACT.—Moonwort (Botrychium Swartz) is a genus of ferns found in high diversity in the Rocky Mountains of southwestern Alberta, Canada. These small, cryptic plants are thought to prefer disturbed areas, such as trail sides. However, this idea may result from survey bias toward accessible areas near trails, or greater ease of spotting these plants in barren areas. Castle Provincial Park and Castle Wildland Provincial Park (CCWPP) are 2 recently established protected areas within this global hotspot of Botrychium diversity. Prior to 2018, provincial and international databases included only 30 records of Botrychium throughout CCWPP. Therefore, their frequency in the parks and their habitat preferences are not well understood. We used new records from the Castle region plus online herbarium records to build a genus-level species distribution model (SDM) and surveyed 24 sites of varying predicted suitability at least 100 m from trails. We then used all known records, including new records gathered during vegetation surveys, to assess habitat associations of any Botrychium species found throughout CCWPP. Botrychium occurred in a wide variety of vegetation types, with some species limited to one vegetation type. Overall, most Botrychium occurrences were on south-facing slopes, in grassland vegetation, 10–100 m away from official marked trails. We discovered 7 new occurrences in surveys at least 100 m from trails. Although 6 of the 7 new off-trail occurrences were found at sites with >40% suitability, the SDM was not a significant predictor of Botrychium occurrence. Our results show that Botrychium occurs across a wide range of vegetation types, topographic conditions, and proximity to trails and there are likely many undiscovered populations in CCWPP.
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    Species distribution models rarely predict the biology of real populations
    (Wiley, 2022) Lee-Yaw, Julie A.; McCune, Jenny L.; Pironon, Samuel; Sheth, Seema N.
    Species distribution models (SDMs) are widely used in ecology. In theory, SDMs capture (at least part of) species' ecological niches and can be used to make inferences about the distribution of suitable habitat for species of interest. Because habitat suitability is expected to influence population demography, SDMs have been used to estimate a variety of population parameters, from occurrence to genetic diversity. However, a critical look at the ability of SDMs to predict independent data across different aspects of population biology is lacking. Here, we systematically reviewed the literature, retrieving 201 studies that tested predictions from SDMs against independent assessments of occurrence, abundance, population performance, and genetic diversity. Although there is some support for the ability of SDMs to predict occurrence (~53% of studies depending on how support was assessed), the predictive performance of these models declines progressively from occurrence to abundance, to population mean fitness, to genetic diversity. At the same time, we observed higher success among studies that evaluated performance for single versus multiple species, pointing to a possible publication bias. Thus, the limited accuracy of SDMs reported here may reflect the best-case scenario. We discuss the limitations of these models and provide specific recommendations for their use for different applications going forward. However, we emphasize that predictions from SDMs, especially when used to inform conservation decisions, should be treated as hypotheses to be tested with independent data rather than as stand-ins for the population parameters we seek to know.
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    The influence of landscape context on short- and long-term forest change following a severe ice storm
    (Wiley, 2019) Lloren, Jed I.; Fahrig, Lenore; Bennett, Joseph R.; Contreras, Thomas A.; McCune, Jenny L.
    1. When deforestation results in small forest fragments surrounded by a non‐forest matrix, forest stands within these fragments experience changes in structure and community composition. They also continue to experience natural disturbances like hurricanes and ice storms. It remains unclear whether the landscape context of forest stands influences plant community response to natural disturbances.2. Using data from surveys of forested plots in the years immediately following and 19 years after a severe ice storm, we measured changes in woody stem density, species richness and beta diversity.3. Plots with greater storm damage had greater gains in stems and species, and greater shifts in community composition. In addition, there were interactions between the degree of storm damage and landscape context. The short‐term ef‐fects of storm damage were magnified in plots with less forest on the surrounding landscape and farther from the forest edge. In plots with high damage, a return towards pre‐storm conditions over the long‐term occurred more often in plots farther from the forest edge compared to those close to the edge.4. Synthesis. Future climate scenarios predict increases in severe weather and accompanying ecosystem disturbance. Our results show that it is important to consider landscape context when assessing the response of forest communities to such disturbances.
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    Using stacked SDMs with accuracy and rarity weighting to optimize surveys for rare plant species
    (Springer, 2020) Rosner-Katz, Hanna; McCune, Jenny L.; Bennett, Joseph R.
    Effective conservation of rare species requires reasonable knowledge of population locations. However, surveys for rare species can be time-intensive and therefore expensive. We test a methodology using stacked species distribution models (S-SDMs) to efficiently discover the greatest number of new rare species’ occurrences possible. We used S-SDMs for 22 rare plant species in southern Ontario, Canada to predict the best survey locations among individual 1-ha cells. For each cell, we weighted distribution model outputs by accuracy and species rarity to create an efficiency value. We used these efficiency values as an index to determine the locations of our field surveys. We conducted field surveys in multi-species cells, “MSC” (areas with high predicted efficiency for multiple species) and single species cells, “SSC” (areas with high probability for only one species) to determine the relative efficiency of a multi-species survey approach. MSC were more than twice as likely as SSC to have at least one rare plant species discovered. Efficiency ranks were also useful in directing surveyors toward incidental discoveries of other rare species that were not modeled. Our technique of using S-SDMs can help direct surveys to more efficiently find rare species occurrences.