Curtis J. Hansen

Abstract Introductions of new crops can provide alternate market opportunities, but also pose ecological risks. New crops lack established management, have uncertain performance issues, and may become weedy in their introduced region. The introduction of hemp (Cannabis sativa L.) into southern Florida poses a unique introduction scenario because of the subtropical climate and no commercial production on record, unlike in other eastern and midwest United States. We assessed escape from cultivation for hemp by tracking establishment and reproduction of volunteer plants from the earliest modern hemp planting in Florida. Hemp is a weed across much of the United States matching its historical distribution and has been assessed to be of high invasion risk for Florida because of its biological attributes, history of escape, and colonization in other states and countries. We conducted monitoring of volunteer plants and a seed establishment experiment in southern Florida and found that hemp volunteer plants occurred in pulses over time, with variable and declining germination. Volunteer plants persisted for up to two years and appeared in areas that were disked and mowed according to USDA approved hemp crop termination procedures. In the seed establishment experiment, we found that hemp established in disturbed soils (∼9% of seeds planted) and that mean plant heights and seed counts were positively related to soil disturbance and nutrient addition. These findings show that hemp plantings should be monitored for volunteer establishment, and containment plans should be in place to control the establishment of volunteer hemp plants in agricultural fields. Our study further illustrates the need for multi-year monitoring and repeat termination procedures to ensure containment of hemp volunteers. There was limited evidence of volunteer establishment in surrounding areas and on undisturbed land. However, seed containment, equipment cleaning, and the monitoring of nearby fields and seed transportation routes remains warranted.

Abstract Trichomes are diverse and functionally important plant structures that vary in response to selection pressures across ecological gradients and evolutionary timescales. Classic hypotheses predict higher investment in trichomes in arid environments, at lower latitudes, and in long-lived species, as well as shifts in trichome production to reduce conflict between defense traits and mutualisms. However, tests of these hypotheses often rely on aggregate trichome metrics and neglect the rich diversity of trichome phenotypes. Here, we collected data on fine-scale patterns of trichome length, density, and type in 52 species of blazingstars (Mentzelia: Loasaceae) and tested whether individual trichome traits were consistent with existing adaptive hypotheses. Contrary to longstanding hypotheses, we found that Mentzelia species tend to display greater trichome investment in less arid environments and at higher latitudes. Barbed trichomes are significantly less common on the upper surface of the leaf, possibly reducing defense-pollination conflict. Species with larger petals (a proxy for reliance on insect pollinators) also shift investment away from insect-trapping hairs on the underside of the leaf. Examining trichome types separately revealed that different morphologies show distinct responses to abiotic and biotic factors, demonstrating the need to consider multiple axes of diversity when testing adaptive hypotheses for complex traits.

Prunus persica (peach), a well-known fruit species belonging to the family Rosaceae, has a long history of human consumption. Its hard and easily preserved fruitstones (endocarps) have often been found at archaeological sites in many parts of the world. However, there are several species within Prunus subg. Prunus sect. Persica with similar stone morphologies. In order to correctly identify the stones of P. persica and related taxa, we first sampled, described and analysed the stone morphological characteristics of all five species in sect. Persica , together with the related taxa P . armeniaca , P . mume and P . salicina . Then detailed fruitstone descriptions and measurements were made together with an illustrated key to the various species, to enable the identification of peaches at species level and to explore and understand the processes of domestication, cultivation and distribution of P. persica and its allies.

AbstractPremiseBiotic disjunctions have attracted scientific attention for the past 200 years. Despite being represented in many familiar plants (such as bald cypress, flowering dogwood, sweetgum, partridgeberry, etc.), the eastern North American (ENA)–Mexican (M) disjunction remains poorly understood. Major outstanding questions include the divergence times of taxa exhibiting the disjunction and environmental/geological processes that may underlie the disjunction. Symphyotrichum Nees (Asteraceae), one of the most diverse genera in the eastern USA, displays several examples of disjunct ENA–M taxa.MethodsWe generated target capture data using the Angiosperms353 baitset and generated the first well‐sampled phylogenomic hypothesis for Symphyotrichum and its close relatives. Focusing on S. subgenus Virgulus, we used MCMCTREE to perform divergence time estimation and the R package BioGeoBEARS to infer ancestral regions and biogeographic transitions between North America and Mexico. Finally, we used the ancestral niche reconstruction method Utremi to test for a role of historical aridification in generating the disjunction.ResultsOur molecular data suggest a recent radiation of Symphyotrichum at the Plio‐Pleistocene boundary (~2.5 mya), with early connections to Mexico in ancestral lineages that closed off shortly after and were followed by vicariance across this region. Except for some present‐day broadly distributed species, there is a complete lack of movement between ENA and M after ~0.5 mya.ConclusionsA reconstructed disjunct distribution of suitable habitat in Pleistocene climatic models corroborates results from biogeographic modeling and confirms glacial cycles are more likely to be associated with the breakup of ENA–M biogeographic connections.

The family Onocleaceae represents a small family of terrestrial ferns, with four genera and around five species. It has a circumboreal to north temperate distribution, and exhibits a disjunct distribution between Eurasia and North America, including Mexico. Historically, the taxonomy and classification of this family has been subject to debate and contention among scholars, leading to contradictory classifications and disagreements on the number of genera and species within the family. Furthermore, due to this disjunct intercontinental distribution and the lack of detailed study across its wide range, this family merits further study to clarify its distributional pattern. Maximum likelihood and Bayesian phylogenetic reconstructions were based on a concatenated sequence dataset for 17 plastid loci and one nuclear locus, which were generated from 106 ingroup and six outgroup taxa from three families. Phylogenetic analyses support that Onocleaceae is composed of four main clades, and Pentarhizidium was recovered as the first branching lineages in Onocleaceae. Molecular dating and ancestral area reconstruction analyses suggest that the stem group of Onocleaceae originated in Late Cretaceous, with subsequent diversification and establishment of the genera Matteuccia, Onoclea, Onocleopsis, and Pentarhizidium during the Paleogene and Neogene. The ancestors of Matteuccia, Onoclea, and Onocleopsis could have migrated to North America via the Beringian land bridge or North Atlantic land bridge which suggests that the diversification of Matteuccia + Onoclea + Onocleopsis closely aligns with the Paleocene-Eocene Thermal Maximum (PETM). In addition, these results suggest that Onocleaceae species diversity peaks during the late Neogene to Quaternary. Studies such as this enhance our understanding of the mechanisms and climatic conditions shaping disjunct distribution in ferns and lycophytes of eastern Asia, North America, and Mexico and contribute to a growing body of evidence from other taxa, to advance our understanding of the origins and migration of plants across continents.

Urban forests are increasingly threatened by invasive shrub species in the understory. Accurate mapping of these species is crucial for effective management of their prevention and mitigation. This study focuses on the detection of invasive shrub species in forested areas of the Chicago metropolitan region using high-density airborne LiDAR data and high-resolution imagery. We analyzed the structural and spectral characteristics of forests with and without invasive shrub species. We tested whether forests with invasive shrub species have a simpler canopy structure than those not invaded, and whether high-density LiDAR based structural metrics are more effective in detecting the presence of invasive shrub species than spectral-based NDVI. Our binomial logistic model demonstrated a test accuracy rate of 93 % for detecting invasive shrub species. Our findings show that forest patches invaded by these species exhibit higher vegetation area density, lower height, and lower NDVI (full leaf on season) values than non-invaded patches. LiDAR-derived canopy structural metrics are shown to be more effective than NDVI for detecting invasive shrub species. To ensure the reliability of our predicted map, we tested correspondence between our invasion estimation map with the ground identified samples that were not used in model testing and training. These validation results demonstrated the predictive ability of our model, showing accuracy rates of 83 % and 77 % for tree survey (DBH > 5 cm) and shrub survey (Height > 1 m & DBH < 5 cm), respectively. Our study demonstrates that LiDAR-derived metrics along with spectral imagery can successfully map invasive shrubs in urban forests.

Bamboos are popular ornamental plants in the EPPO region though some of them have been observed to escape the confines of planting and establish in the natural environment. The aim of this study is to produce a risk‐based list of bamboo species which are recorded in the natural environment in the EPPO region, and to determine if any of the species require a pest risk analysis. Forty‐two bamboo species were identified as being present in the natural environment in the EPPO region. Of these, 11 species fulfil the three pre‐selected criteria for species to be considered potentially harmful: (1) the species is naturalized in at least one EPPO country; (2) the species has a running dispersal behaviour (leptomorph); and (3) there is evidence of invasive behaviour in at least one country. These 11 species were prioritized using the EPPO prioritization process for invasive alien plants. Owing to their high spread potential and potential high impact, three species, namely Phyllostachys aurea, Pseudosasa japonica and Sasa palmata, proceeded to the second stage of the prioritization process (risk management stage). All three species were identified as having a high priority for a pest risk analysis. In 2024, the EPPO Panel on Invasive Alien Plants agreed with the results of the study but noted that further information on impacts would be beneficial and therefore the Panel agreed that Ph. aurea and S. palmata should be added to the EPPO Alert List along with the already included P. japonica. This will raise awareness of these species in the region and further information can be gathered to support the development of a risk assessment.

The cabbage seedpod weevil (CSW), Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae) is an important pest of brassicaceous crops, including canola ( Brassica napus Linnaeus). CSW consumes seeds of its host from inside the developing pods. It was introduced to North America from Europe and now occurs throughout the United States of America and Canada. Climate is one of the most important factors that determines species distribution and abundance. CLIMEX is a bioclimate model development application. Based on climate inputs, bioclimatic simulation models are tools that predict the potential geographic distribution and abundance of insects and plants. This study updated a previous bioclimatic model for CSW and presents a new model for canola. Validated models were used to conduct bioclimatic analysis of both species, the results of which provide a better understanding of how climate affects spatial distribution and abundance of CSW and the distribution and yield of canola. Application of incremental temperature and moisture scenarios were used to predict the spatial relationship of CSW risk and canola yield. We anticipate that the canola model will be applied to future bioclimatic studies of pests and beneficial insects of canola. Both the CSW and canola model can be used in climate change studies using datasets for predicted future climates.

This study assesses the potential effects of climate change on the distribution of the Drosera genus, which is a carnivorous plant group widely distributed in South America. The Drosera species act as adequate biological indicators, with their fitness performance reflecting the health of ecosystems. Through the application of species distribution models and the analysis of bioclimatic variables, the adaptability of 39 Drosera species to evolving climatic conditions was assessed, revealing their capacity to thrive in diverse habitats, from nutrient-deficient soils to regions with high atmospheric CO2 concentrations. While many species show adaptability, environmental forecasts using two General Circulation Models indicate a decrease in favorable habitats by 2050 and 2070. It is expected that about 71.79 % of species will encounter shrinking habitat suitability, while 28.21 % may see an increase in habitat suitability. This anticipated habitat loss underscores the critical need for proactive conservation measures, including habitat preservation, ecological restoration, assisted migration, and genetic conservation efforts, to counteract the adverse effects of climate change. Additionally, the study highlights the importance of refining species distribution models and deepening our understanding of the ecological dynamics of Drosera species in response to environmental changes. By offering insights into the challenges and opportunities for conserving Drosera species in a changing climate, this work lays a solid groundwork for future ecological research and conservation initiatives. It calls for an integrated approach that combines scientific inquiry with strategic conservation actions to ensure the survival of these unique plant group and ecological integrity during global environmental shifts.

Lonicera japonica, an importante rsource plant, possesses significant medicinal, economic, and ecological value. To understand its response to climate change and to optimize its conservation and utilization, this study employed the Biomod2 ensemble model to predict its potential distribution under future climate scenarios and identified key environmental factors influencing its distribution. The results showed that under current climatic conditions, the potential distribution of honeysuckle is primarily concentrated in low-altitude regions of central and eastern China and the Sichuan Basin. In future scenarios, the overall distribution pattern changes less, and the area of highly suitable habitats slightly decreases by 0.80%. Distribution analysis indicated a trend of northward migration towards higher latitudes. Temperature-related factors, including temperature seasonality, the minimum temperature of the coldest month, the mean temperature of the coldest quarter, and the annual mean temperature, were identified as dominant factors affecting its distribution. The Biomod2 ensemble model significantly improved the precision and accuracy of suitability predictions compared to single models, providing a scientific basis for predicting the future geographic distribution of honeysuckle and for establishing and utilizing its cultivation regions in China.