In many ecological communities, the effects of exotic species are likely to extend beyond their direct interactions with natives, due to indirect effects. This dynamic might be particularly consequential in cases where invasive insects or other exotic herbivores target foundation plant species in the communities they invade. In this study at a site in western Massachusetts, we used experimental transplants to gauge the potential effects of a decline in the evergreen conifer Tsuga canadensis due to ongoing spread of two exotic insect pests on a liverwort, Bazzania trilobata, whose distribution is closely linked to dense stands of this conifer in the northeastern USA. After 4 years, transplanted B. trilobata samples moved to forest areas with lower abundance of T. canadensis declined significantly, particularly on sites with higher solar radiation, as determined by local slope and aspect. In addition, samples manually cleared of deciduous leaf litter were ∼ 17% larger than those exposed to natural accumulation of leaf litter, indicating a direct negative effect of deciduous trees on the liverwort that might increase as these tree species replace T. canadensis lost to invasive pests. A parallel experiment documented high mortality of B. trilobata (55%) when subjected to open canopy conditions similar to those resulting from selective “salvage” logging of hemlock in the region. These results indicate that the spread of exotic insect pests targeting T. canadensis is likely to produce strong indirect negative effects on the liverwort B. trilobata, via diminished commensal interactions with the conifer and increased amensalistic effects from the deciduous tree species that commonly replace it.

Lilium michiganense Farw. (Michigan lily) is a rare species native to the even rarer tallgrass prairie biome. In Iowa, extensive conversion of native prairie lands for agriculture has led to tallgrass plant communities existing only in scattered fragments. Fragmented landscapes provide challenges for animal-pollinated species, especially for rare plant species. Unfortunately, there is little published literature about the reproductive biology of many species, including the Michigan lily. We recorded pollinators of Michigan lily in three remnant prairies in northwest Iowa. We also examined nine 10- ×10-m tallgrass prairie plots, including Michigan lilies for plant species composition, because that may influence pollinator availability. Species composition (analysis of similarity, R = 0.93, P = 0.04) of the three prairies was significantly different. Species flowering coincident with Michigan lilies were both bee- and butterfly-pollinated species (floral visitors/pollinators were recorded on individual flowers of Michigan lilies only). This suggests that plant-species composition is not a limiting factor in pollination for the Michigan lily. Indicator species analysis identified distinct indicator species for each prairie; however, neither those species nor the most abundant animal-pollinated species were flowering at the same time as the Michigan lily. The observed pollinator of Michigan lily was the nonnative honeybee (Apis mellifera L.) with an 89% success rate. No other floral visitors to the lilies were observed throughout the study. Additional studies are needed to test for differences in pollinator availability and abundance because of annual weather variability.

Vicia ocalensis Godfrey & Kral (Ocala vetch) is a declining endemic plant that is state-listed as endangered in Florida and as critically imperiled globally. This perennial vine is historically known from only three populations along the shorelines of separate spring systems within the Ocala National Forest. One of these populations recently rejuvenated after being absent for 15 years. All populations have experienced great annual fluctuations in size, and are increasingly threatened by recreational use of the springs, herbicide treatment, and other habitat disturbances. The aims of this study are to assess genetic diversity within and between the three historical populations of V. ocalensis and characterize habitat supporting the two extant populations of V. ocalensis to inform conservation strategies. We analyzed 743 amplified fragment length polymorphism (AFLP) markers. Our AFLP results show evidence of high inbreeding and weak genetic differentiation among populations. Genetic diversity within Population 1 and Population 3 was lower than Population 2. Complementary monitoring data over the last 10 yr shows population size declines in these three populations. The low genetic diversity and inbreeding is a concern for this species, especially coupled with habitat loss, degradation, and fragmentation. Our analysis of habitat suggests that germination substrate is a key component in determining suitable habitat for V. ocalensis, but understory and overstory plants may also influence habitat suitability. Habitat protection, restoration of similar habitats, population introductions, and ex situ preservation are all recommended for this species.

Phragmites australis is regarded as an important cosmopolitan species that has the potential to enhance the structure, function, and stability of the Yellow River delta, China. This study investigated the responses of Phragmites australis to various hydrologic and salinity conditions with a focus on plant growth, leaf morphology, biomass and allocation, gas exchange, and chlorophyll fluorescence physiology. The plants were subjected to a full factorial design with three soil salinity levels, two levels of rainfall amounts, and two watering frequencies. Results from a 62-day experiment revealed that both higher soil salinity and lower rainfall amounts greatly reduced plant growth, average leaf area, and photosynthetic characteristics (e.g., net photosynthetic rate, transpiration rate, and stomatal conductance). The interactive effects of soil salinity and rainfall amounts were found on most gas-exchange parameters and biomass parameters. Lower rainfall frequency reduced total chlorophyll concentration, intercellular carbon dioxide, and stomatal limitation value, but the total biomass and biomass of each part were not affected. Although it may suffer from higher salinity and drought in the long term, Phragmites australis will continue to dominate wetland communities of the Yellow River delta, at least in the short term.

Lianas are known as both disturbance creators and beneficiaries, and through their high competitiveness for resources, they possess the potential to significantly affect forest ecosystems. Euonymus fortunei (Turcz.) Hand.-Mazz. (wintercreeper) is an evergreen liana that is steadily invading forests in eastern North America, disrupting native plant communities and altering ecosystem functions. Establishment in novel environments may be limited by dormancy-breaking and germination requirements, parameters for which little is known for many invasive species, but especially for wintercreeper. We examined the mechanisms of seed dormancy by conducting a “move-along” experiment using fresh (FR) and maternally persisting (MP) seeds. Additionally, we sought to characterize the nature of seed dispersal by birds by deploying seed traps within an invaded forest in central Kentucky. We report that wintercreeper seeds display conditional, nondeep physiological dormancy. Although germination occurs at a high percentage and rate after cold stratification, a cold period is only facultative to break dormancy. Although FR seeds had greater viability (98.6%) vs. MP seeds (85.7%), the latter experienced earlier germination (an average of 41 days, across all treatments). We observed the presence of polyembryos in 24.4% of germinating wintercreeper seeds. Our findings indicate that bird-mediated seed dispersal occurs throughout the winter from seeds that persist aboveground on maternal lianas. Taken altogether, these results suggest that wintercreeper is capable of long distance, animal-assisted dispersal as well as recruitment in areas with mild or nonexistent winters. These data contribute to the growing body of wintercreeper-invasion literature, bringing further attention to an emerging invader and aiding land managers in prioritizing management strategies in the prevention and eradication of this species.

Nonindustrial private forest (NIPF) landowners own a substantial amount of acreage within the southern USA. The NIPF landowners are usually less financially motivated and implement relatively less-intensive management options, such as partial harvesting, to pursue a variety of multiuse objectives. Understanding how developmental processes are influenced by partial harvesting is vital to constructing viable silvicultural prescriptions. Liquidambar styraciflua L., Quercus alba L., and Ostrya virginia (Mill.) K. Koch seedling (10–105 cm tall) growth and physiology were investigated in relation to different gap sizes and within-gap positions in a mixed Pinus L.–hardwood forest. The levels of photosynthetically active radiation that penetrated the overstory conditions allowed shade-intolerant Liquidambar styraciflua to produce greater (mean ± SE) monthly height and groundline diameter growth (12 ± 0.94 cm and 0.2 ± 0.02 cm, respectively) than Ostrya virginia (8 ± 0.87 cm and 0.1 ± 0.02 cm, respectively) and Quercus alba (4 ± 0.51 cm and 0.1 ± 0.01 cm, respectively), which was facilitated, in part, by significantly higher photosynthetic rates (P < 0.01). Solely manipulating the overstory conditions within mature, Pinus-hardwood mixtures may not be adequate for Quercus regeneration in those mixtures and is conducive to Liquidambar styraciflua obtaining a more-dominant canopy position in the future.

Sandy gaps in the shrub matrix of oak (Quercus L.)–saw palmetto (Serenoa repens (W. Bartram) Small) scrub are created by fire but typically close quickly because of rapid regrowth. Such gaps are important habitat features for rare scrub flora and fauna and appear to have been more common in the historical landscape. We followed, from 1993 to 2016, the dynamics of 12 gaps (32.2–98.1 m²) created by burning slash piles as part of restoration of long-unburned scrub. Gaps closed slowly, primarily by canopy spread of oaks around the gaps. In the absence of subsequent fire, gaps closed within approximately 12 yr. When burned a second or third time, gap area increased to near the initial after-burn size but then declined in area more rapidly than after the initial fire. Vegetation that reestablished in gaps differed from that of the scrub matrix in having less cover of scrub oaks, less cover of S. repens > 0.5 m, greater cover of native shrubs and forbs > 0.5 m, and more bare ground. Soil heating from slash-pile burning killed the roots and rhizomes from which scrub oaks, Serenoa, and ericaceous shrubs sprout; this altered and slowed the after-fire recovery.

The vascular flora at 50 small sidewalk plots in Greenpoint, Brooklyn, Kings County, NY, and also bordering St. John's University, Jamaica, Queens County, NY was identified and compared during spring and fall 2007 through the spring and fall 2011 growing seasons. One hundred twenty-one vascular plant species within 94 genera and 37 families have been identified. Eighty-four taxa were identified in Brooklyn while 71 taxa were identified in Queens; many taxa in Brooklyn were also found in Queens as well. Ninety-six taxa were identified at both sites in the spring while 55 taxa were identified in the fall. The Asteraceae (22 species) and Poaceae (15 species) were the largest families in the flora. Eighty-five taxa, 69% of the flora, are not native to the region. Thirty-one taxa were observed only once during the 5-yr study; those observed only once, twice, and three times composed 50% of the flora. A parsimony algorithm was used to evaluate the distribution and co-occurrence of 121 vascular plant species identified at the above sites in Brooklyn and Queens in the fall and spring of 2007 to 2011. A total of 1,000 plots were sampled during the 5-yr study. The hierarchical cluster analysis forms two major clusters representing a Queens section, Queens fall 2007 to Queens fall 2011, and a Brooklyn section from Brooklyn fall 2007 to Brooklyn spring 2009. The data did not have enough resolution to produce a single unambiguous tree. This may be explained by the dynamic nature of these “islands,” as many species colonize these “islands” briefly and disappear. The high diversity at the sidewalk plots may be a product of local disturbance.

Couepia is a monophyletic and exclusively Neotropical genus of Chrysobalanaceae, occurring mainly in lowland tropical forests. In eastern Brazil, Bahia is the state with the highest species richness for both the genus and family, with significant diversity in the coastal Atlantic Forest. Here we report the discovery of Couepia oxossii from Atlantic Forest, which was initially misidentified as Couepia pernambucensis. The new species is described and illustrated, and comments on its morphological traits and conservation status are also provided.