We sought to determine if elevated CO₂ resulted in long-lasting changes to plant structure and function, particularly disturbance response patterns. Minimal legacy effects were observed 1 yr after the termination of a previous long-term experiment; however, those observations were based on 1 yr of data and only focused on fine root growth, herbivory, and arthropod diversity. We examined above- and belowground biomass inside the footprints of chambers from a former long-term elevated CO₂ experiment in a scrub-oak community 7 yr after CO₂ enrichment ceased and 2 yr after fire. Aboveground biomass was 40.6% higher in the previously elevated plots compared with ambient plots, suggesting that there are legacy effects in the form of more rapid aboveground recovery from fire on previously elevated CO₂ plots. Belowground biomass exhibited minimal change since the historic CO₂ enrichment, suggesting that differences were a result of the original treatment. After disturbance, regrowth occurs via sprouting from large belowground structures; thus changes in aboveground recovery are likely due to changes to belowground biomass caused by altered atmospheric CO₂. Elevated CO₂ has significantly affected disturbance recovery patterns in this community. These changes have the potential to alter plant carbon allocation patterns in frequently disturbed systems.

We conducted lichen surveys on mixed broadleaf-conifer plots along an elevation gradient in a northern hardwood forest to test whether current community patterns were more indicative of a gradient in atmospheric inputs of sulfur and nitrogen or a gradient of moisture availability with elevation gain. Our lichen surveys of 12 0.38-ha plots throughout the Hubbard Brook Experimental Forest in north-central New Hampshire revealed four new species records for the state: Heterodermia squamulosa, Hypotrachyna afrorevoluta, Parmelia fertilis, and Parmotremaarnoldii. Lichen composition was related to elevation, tree basal area and size of the largest tree. The percent of fruticose lichen species was significantly, positively related to elevation. Species richness also increased with elevation, but was only significantly related to aspect, particularly southness. Species abundance is related positively to tree basal area. The pollution indices were mainly correlated to each other though the sulfur index was correlated to the second ordination axis. Overall, the Hubbard Brook valley appears to have a relatively diverse lichen assemblage related more strongly to plot characteristics than to pollution indices.

Effective pollination is essential to the ability of introduced plant species to establish and spread in novel habitats. In this study we examine the pollination biology of the introduced tree species Triadica sebifera on the Gulf Coast of the United States. We assessed its potential for reproduction via autogamy, self-fertilization, wind pollination, and pollen dispersal by insects, and compared visitation by native and introduced pollinators. We found little evidence of autogamy in emasculated inflorescences, and though trees were self-compatible, protandry within inflorescences and synchrony of flowering on branch systems were effective at preventing self-fertilization. Pollen was poorly dispersed by wind, and no pollen was found on traps 8 m from source trees. Although numerous insects visited inflorescences, only bees in the families Apidae and Halictidae carried more than traces of pollen. Both the introduced honeybee, Apis mellifera, and native bees carried large amounts of pollen, and native bees dominated the visitor community at three of four study sites. The results suggest that T. sebifera is primarily outcrossing and bee-pollinated, and is effectively pollinated by native generalist bees in its introduced range.

A study on the reproductive biology of the federally endangered Physaria globosa was conducted near Hartsville, TN, at one of the largest known populations of the species from February through July 2016. Objectives included (a) establishment of baseline reproductive phenology for P. globosa, (b) documentation of the diversity and frequency of floral visitors, and (c) determination of effective insect pollen vectors. Flowers were open for three days and displayed characteristics typical of outcrossing. Six insect species were identified as effective vectors for P. globosa pollen, including two dipterans and four halictid bees. While pollen loads were not significantly different among the vectors, floral visitors were ranked by frequency in descending order as follows: Nemotelus bruesii, Toxomerus geminatus, Lasioglossum illinoense, Halictus ligatus, Lasioglossum versatus, and Augochlorella striata. Information on natural history of this species is vital to aiding conservation efforts for P. globosa across its range.

Plant interactions influence species distribution in an ecosystem. These interactions may be related to phylogeny because close relatives might grow apart due to stronger competition. Physical traits, such as size, may also influence species distribution. We tested whether woody plants from phylogenetically distant species grow closer to each other than phylogenetically closer ones in desert scrubland, pine-oak forest, and thornscrub in northeastern Mexico. The study was carried out using nearest neighbor physical distances. Plant crown diameter was tested for correlation with physical distance to neighbor plants to see if plant size influenced distance to neighbor individuals. Phylogeny did not correlate with physical distance between plants. Crown diameter was correlated with physical distance to the nearest neighbor only in desert scrubland. Our hypothesis of greater physical distance between closely related species was not supported by our results, and the opposite was found for 20% of the species studied.

Exotic species that become invasive can have a strong impact on the success of native species because of traits that enhance their competitive abilities. This study investigates three potential trait differences between common invasive and native shrubs that could enhance the competitive success of invasives: resistance to herbivory, length of autumn leaf retention, and timing of spring leaf emergence. We measured herbivory per plant by leaf-chewing insects, autumn leaf color change and retention, and spring leaf-out in five native and five invasive shrub species in Wildman Woods near Richmond, Indiana, during the fall of 2014 and the spring of 2015. Although we found variation among species, native plants as a group had significantly greater percent leaf herbivory per plant compared to invasive plants, while invasive plants kept chlorophyll significantly later in autumn and had longer leaf retention. Invasive plants also leaf out slightly earlier than native species. Our findings in 2014 were very similar to previous unpublished work in the same area on several of the same species in 2002, 2004, and 2007, suggesting that these patterns are consistent between years. Overall, we found evidence that lower herbivory rates, longer leaf retention in fall, and perhaps earlier leaf-out in spring could improve the competitive abilities of invasive shrub species through increased season-long photosynthesis.

This study intends to verify whether edaphic factors contribute to the structural arrangement of the woody restinga vegetation in the Northeast region of Brazil, and whether there is similarity between the restingas of the Amazonian and Northeast coasts. To sample the restinga vegetation of Maranhão State, we used the point-quarter method. In each quadrant, we collected soil samples to determine the chemical and physical variables. We built a matrix to correlate the soil variables with the species, using the canonical correspondence analysis, and used cluster analysis for the similarity. The analysis resulted in 32 species and 17 families. Astrocaryum vulgare, Protium heptaphyllum, Anacardium occidentale, Coccoloba latifolia, and Tilesia baccata presented higher importance value. The Shannon's diversity index was 2.9 nat.ind-¹, and Pielou's equality was 0.8. The correlation analysis showed that only Chioccoca alba and Mouriri guianensis presented positive correlation with magnesium, organic matter, sum of bases, and base saturation. Regarding similarity, the flora of the restinga in the present study resembles the restinga of Alcântara, in Maranhão State, and an area of Ceará State. Finally, we assert that such studies of the Northeast coastal vegetation constitute an important tool to assist in the development of strategies for biodiversity conservation.

The decline and near extirpation of lichens from urban areas was documented worldwide over the past 2 centuries, with the lowest diversity observed in many cities during the 1960s and 1970s. One major contributing factor to this observed decline was high levels of unregulated air pollution, which has a strong negative impact on lichen growth and survival. Since then lichens have begun recolonizing cities, in many cases at a rapid rate. New York City followed these same trends in urban lichen diversity changes. To better understand the current state of New York City lichen diversity, we have been conducting surveys at green spaces throughout the city. During one of these surveys we found a single thallus of Usnea on one very large, old red oak (Quercus rubra L.) at Woodlawn Cemetery in the Bronx. The individual was too poorly developed to identify by its morphology and chemistry, so we took a DNA barcoding approach. Molecular data confidently assigned the thallus as Usnea mutabilis Stirton. Finding this thallus was highly notable, as it is the first report of an Usnea from New York City since 1824. The thallus is about 1.5 cm long, which suggests that it established within the last 30 yr. This finding highlights the continued improvement of urban environments for lichen recolonization, and the importance of cemeteries in providing stable green spaces for urban biodiversity.