Nursing Back to Health: Shrubs Facilitate the Restoration of Native Forbs with Reductions in Non-Native Competition in an Invaded Arid Shrubland

Restoring native species to invaded arid ecosystems is challenging as non-native species often limit native species establishment, which limits success. Nurse plant facilitation may be utilized to improve native species establishment through reductions in abiotic and biotic stresses but this has not yet been tested for native forb restoration in invaded arid ecosystems. Five native forb species were seeded in shrub and open microsites, with and without exclosures. Non-native removals were done to determine if shrubs could facilitate native forbs establishment in an invaded arid shrubland. Shrubs facilitated native species, and interestingly, most natives co-existed with non-natives. However, non-native removals had a large positive effect for two less competitive native species. Exclosures overall were not effective at increasing native density. Seeding natives with shrubs and non-native removals are recommended as effective strategies for increasing native species establishment in invaded arid systems

Shrubs indirectly increase desert seedbanks through facilitation of the plant community

The mechanisms supporting positive ecological interactions are important. Foundation species can structure desert biodiversity by facilitating seedbanks of annual plants, but the direct and indirect mechanisms of shrub effects on seedbank have not been experimentally decoupled. We conducted the first test of shrubs increasing seedbank densities through direct effects on the seedbank (i.e. shrub seed-trapping, animal-mediated dispersal) and indirect effects by facilitating the annual plant community (i.e. seed deposition, annual seed-trapping). Two distinct desert ecosystems were used to contrast transient seedbank densities in shrub and open microsites by manipulating annual plant density and the presence of the persistent seedbank. We measured transient seedbank densities at the end of the growing season by collecting soil samples and extracting seeds from each respective treatment. Transient seedbank densities were greatest in shrub canopies and with relatively higher annual plant densities. The persistent seedbank contributed to transient seedbank densities only in one desert and in the open microsite. Shrubs indirectly increased seedbank densities by facilitation the seed production of the annual plants. Therefore, shrubs are increasing seedbank independently of the annual plant community, likely through trapping effects, and dependently by facilitating seed production of the annuals. These findings provide evidence for a previously undescribed mechanism that supports annual seedbanks and thus desert biodiversity. We also identify shrubs as being significant drivers of desert plant communities and emphasize the need to consider multiple mechanisms to improve our ability to predict the response of ecosystems to change.York University Librarie

Conservation Conundrum: At-risk Bumble Bees (Bombus spp.) Show Preference for Invasive Tufted Vetch (Vicia cracca) While Foraging in Protected Areas

In recent decades, some bumble bee species have declined, including in North America. Declines have been reported in species of bumble bees historically present in Ontario, including: yellow bumble bee (Bombus fervidus) (Fabricus, 1798), American bumble bee (Bombus pensylvanicus) (DeGeer, 1773), and yellow-banded bumble bee (Bombus terricola) (Kirby, 1837). Threats contributing to bumble bee population declines include: land-use changes, habitat loss, climate change, pathogen spillover, and pesticide use. A response to the need for action on pollinator preservation in North America has been to encourage ‘bee-friendly’ plantings. Previous studies show differences in common and at-risk bumble bee foraging; however, similar data are unavailable for Ontario. Our research question is whether there is a difference in co-occurring at-risk and common bumble bee (Bombus spp.) floral use (including nectar and pollen collection) in protected areas in southern Ontario. We hypothesize that common and at-risk species forage differently, predicting that at-risk species forage on a limited selection of host plants. We conducted a field survey of sites in southern Ontario, using observational methods to determine bumble bee foraging by species. The results of a redundancy analysis show a difference in foraging between common and at-risk bumblebee species. At-risk bumble bee species show a preference for foraging on invasive, naturalized Vicia cracca (tufted vetch). This finding raises the question of how to preserve or provide forage for at-risk bumble bees, when they show an association with an invasive species often subject to control in protected areas.York University Librarie

The Conservation Management and Ecology of Northeastern North American Bumble Bees

Bumble bees (Bombus spp.; Apidae) are among the pollinators most in decline globally with a main cause being habitat loss. Habitat requirements for bumble bees are poorly understood presenting a research gap. The purpose of my dissertation is to characterize the habitat of bumble bees at different spatial scales using: a systematic literature review of bumble bee nesting and overwintering habitat globally (Chapter 1); surveys of local and landcover variables for two at-risk bumble bee species (Bombus terricola, and B. pensylvanicus) in southern Ontario (Chapter 2); identification of conservation priority areas for bumble bee species in Canada (Chapter 3); and an analysis of the methodology for locating bumble bee nests using detection dogs (Chapter 4). The main findings were: current literature on bumble bee nesting and overwintering habitat is limited and biased towards the United Kingdom and agricultural habitats (Ch.1). Bumble bees overwinter underground, often on shaded banks or near trees. Nests were mostly underground and found in many landscapes (Ch.1). B. terricola and B. pensylvanicus have distinct habitat characteristics (Ch.2). Landscape predictors explained more variation in the species data than local or floral resources (Ch.2). Among local variables, floral resources were consistently important throughout the season (Ch.2). Most bumble bee conservation priority areas are in western Canada, southern Ontario, southern Quebec and across the Maritimes and are most often located within woody savannas (Ch.3). Climate change is predicted to shift priority areas to more northerly latitudes and to higher elevations (Ch.3). These priority areas do not overlap highly with current protected areas (Ch.3). Using detection dogs to locate the scent of bumble bee nests was more nuanced than expected (Ch.4). The detection distance for nests was short, so dogs needed to conduct detailed searches for nests (Ch.4). Nests may also have multiple entrances which complicates confirming detections made by dogs (Ch.4). The challenges with deploying detection dogs to locate bumble bee nests could be mitigated with careful study design should be carefully considered in future research. This research addresses many gaps in our understanding of bumble bee habitats and will be valuable in informing conservation policy

MSc thesis papers .xls

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Articles retained for a systematic review of the stats used in restoration ecology

<p>A systematic literature search was conducted using ISI Web of Knowledge on October 2, 2014 with the following search terms: restor* AND grass* OR savanna AND (non-native* OR invas* OR invad* OR alien). The search was then refined to include only articles within the ‘Ecology’ Web of Science category which resulted in 340 articles. These articles were then screened to remove reviews and any articles not relevant to restoration ecology. This resulted in 103 retained articles for the systematic review (shown here). These articles were then individually analyzed and data including year of publication, average citation rate per year, diversity of statistical tests, type of tests, whether assumptions were tested, sample size and number and type of factors used were extracted</p

A global meta-analytic contrast of cushion-plant effects on plants and on arthropods

Nurse plant facilitation is a commonly reported plant–plant interaction and is an important factor influencing community structure in stressful environments. Cushion plants are an example of alpine nurse plants that modify microclimatic conditions within their canopies to create favourable environments for other plants. In this meta-analysis, the facilitative effects of cushion plants was expanded from previous syntheses of the topic and the relative strength of facilitation for other plants and for arthropods were compared globally.The abundance, diversity, and species presence/absence effect size estimates were tested as plant responses to nurse plants and a composite measure was tested for arthropods. The strength of facilitation was on average three times greater for arthropods relative to all plant responses to cushions. Plant species presence, i.e., frequency of occurrence, was not enhanced by nurse-plants. Cushion plants nonetheless acted as nurse plants for both plants and arthropods in most alpine contexts globally, and although responses by other plant species currently dominate the facilitation literature, preliminary synthesis of the evidence suggests that the potential impacts of nurses may be even greater for other trophic levels

The dataset for A global meta-analytic contrast of cushion-plant facilitation of plants and arthropods

<p>https://peerj.com/articles/265/</p> <p><br>Nurse plant facilitation is a commonly reported plant–plant interaction and is an important factor influencing community structure in stressful environments. Cushion plants are an example of alpine nurse plants that modify microclimatic conditions within their canopies to create favourable environments for other plants. In this meta-analysis, the facilitative effects of cushion plants was expanded from previous syntheses of the topic and the relative strength of facilitation for other plants and for arthropods were compared globally.The abundance, diversity, and species presence/absence effect size estimates were tested as plant responses to nurse plants and a composite measure was tested for arthropods. The strength of facilitation was on average three times greater for arthropods relative to all plant responses to cushions. Plant species presence, i.e., frequency of occurrence, was not enhanced by nurse-plants. Cushion plants nonetheless acted as nurse plants for both plants and arthropods in most alpine contexts globally, and although responses by other plant species currently dominate the facilitation literature, preliminary synthesis of the evidence suggests that the potential impacts of nurses may be even greater for other trophic levels.</p> <p> </p

Identifying conservation priority areas for North American bumble bee species in Canada under current and future climate scenarios

Abstract Many bumble bee species are declining globally from multiple threats including climate change. Identifying conservation priority areas with a changing climate will be important for conserving bumble bee species. Using systematic conservation planning, we identified priority areas for 44 bumble bee species in Canada under current and projected climates (year 2050). Conservation priority areas were identified as those that contained targeted amounts of each species predicted occurrence through climate envelope models, while minimizing the area cost of conserving the identified conservation priority areas. Conservation priority areas in the two periods were compared to established protected areas and land cover types to determine the area of current and future priority sites that are protected and the types of landscapes within priority areas. Notably, conservation priority areas were rarely within established protected areas. Priority areas were most often in croplands and grasslands, mainly within the mountain west, central and Southern Ontario, Northern Quebec, and Atlantic Canada under all climate scenarios. Conservation priority areas are predicted to increase in elevation and latitude with climate change. Our findings identify the most important regions in Canada for conserving bumble bee species under current and future climates including consistently selected future sites

Net plant-plant interactions change in magnitude along gradients of environmental stress and time

<p>Conference for CSEE - Genomes to Biomes Montreal 2014</p