Seed dispersal structures plant populations and communities but may be affected by forest fragmentation. Recent work demonstrates that white-tailed deer (Odocoileus virginianus Zimmerman) can be important seed dispersers in North American forests, potentially moving seeds over long distances. However, little is known about the role of deer as seed dispersal agents in landscapes characterized by small, isolated forest patches. The objectives of this study were to (a) determine how habitat structure influenced the spatial distribution of deer activity, and (b) describe which plant species and traits were dispersed by deer in a highly fragmented, agricultural matrix. I collected deer fecal pellet groups from 10 forest patches in plots that ranged from 10 to 100 m from forest edge. Pellet groups were cold-stratified and planted in a greenhouse to quantify seeds dispersed by deer. The number of pellet groups collected was highest near forest edges but was not influenced by patch size or isolation; 258 seedlings from 15 species emerged from collected pellets, with three species contributing 80% of seedlings. Most seedlings emerging from deer pellets were herbaceous, nonnative plants with a foliage-as-fruit dispersal mode. Plants with these traits typically perform well in high-light habitats, such as forest edges, where deer are most active. These results suggest that while seed dispersal by deer is common in highly fragmented forest patches, it is most likely to benefit shade-intolerant herbaceous species, maintaining populations of those plants along forest edges.

American beech (Fagus grandifolia Ehrh.) regenerates both from seed and also clonally via root sprouts. Regenerating beech saplings often form dense and depauperate understories that cast deep shade and displace co-occurring species. The relative proportion of saplings that originate from seed versus root sprouts varies widely throughout the range of beech. Although the cause for that variation remains unclear, it may be linked to canopy or soil disturbances, the spread of beech bark disease (BBD), or overabundant deer. Here, we asked whether the long-term exclusion of deer and the absence of BBD would favor the regeneration of saplings (20–150 cm tall) of seed origin versus those of sprout origin. We addressed this question using deer exclosures (16 and 60 yr old) and paired controls in one forest in Pennsylvania where BBD had caused major adult mortality and another where BBD was not present. We found that excluding deer significantly decreased the relative proportion of root sprouts from approximately 60% to approximately 25% in each forest, regardless of stand age, exclosure age, soil type, and presence or absence of BBD. Our findings provide evidence that deer, acting as herbivores, seed predators, agents of physical disturbance, or all of those simultaneously, create forest understories where root sprouts predominate. Although speculative, our results may apply to large regions because deer have been overabundant throughout much of the geographic range of American beech.

Dasistoma macrophylla (Nutt.) Raf. is a photosynthetically competent hemiparasitic plant known to parasitize 21 different tree species. How different tree species vary in quality as hosts for this hemiparasite and how parasitism affects host growth have not been explored. We tested the hypothesis that D. macrophylla form more vascular connections, known as haustoria, to roots of the tree species that promotes greater growth of the hemiparasite in a greenhouse experiment. Juvenile Acer saccharum Marshall (sugar maple), a known host, and Quercus macrocarpa Michx. (bur oak), a previously untested species common to the locality, were grown alone or with one seedling of D. macrophylla derived from one of two populations. Additional D. macrophylla seedlings were grown alone. After 17 wk, dry shoot and root mass of the tree, dry shoot, and root mass of the hemiparasite, and the number of haustoria formed by the hemiparasite were determined. Dasistoma macrocarpa grew better with A. saccharum than it did with Q. macrocarpa. Growth of hemiparasites in the absence of a host was intermediate to growth with either tree. Consistent with greater growth on A. saccharum, D. macrocarpa formed significantly more haustoria on A. saccharum, and both shoot and root growth of maples was strongly reduced. The hemiparasite formed few connections with the bur oak, and shoot and root mass of Q. macrocarpa was unaffected by the parasitism. This study supported the hypothesis that tree species differ in quality as hosts, and D. macrophylla adversely affect valuable hosts.

Over the past century, the abundance of many plant species has declined noticeably, including in the herbaceous understory of temperate deciduous forests. Two separate censuses of Trelease Woods in Illinois, USA, one in 1994–95 that was repeated in 2015, and a second made annually from 1994–2015, indicated major losses for herb species. Quadrat frequency, flowering quadrat frequency, number of species, number of species in flower, number of individuals, and species diversity (H′) all declined greatly over the census period. Most species saw a marked decline in frequency and density, with the number of individuals declining by two-thirds and some species disappearing entirely. Gains from new colonization were minor in comparison. Among persisting species, almost all became shorter and stopped flowering. Number of individuals per species in 1994 and percentage of individuals lost by 2015 were not related. Spring ephemeral species had less loss in frequency and percentage of individuals lost per species than four other phenological syndromes. Although multiple factors changed during the study period, the specific mechanisms behind these biodiversity changes were not addressed by the study. This biodiversity loss is expected to continue and persist with little chance of recovery for dispersal-limited herb species in this isolated, fragmented forest.

This article presents the discovery of earliest known references to the cultivation of Japanese knotweed, Reynoutria japonica, in North America. As described in articles from 1868, 1872, and 1875 there were three distinct introductions of the plant in the 1860s, two from Europe and one from Japan. The European introductions consisted of the now widespread, seedless female clone introduced into commerce by Philipp von Siebold in the 1840s and a dwarf, seed-producing variety with reddish stems, probably also introduced by von Siebold. The introduction from Japan was sent by Thomas Hogg to his brother James's nursery in New York City and produced “an abundance of rose-colored fruits.” Serendipitously, an herbarium specimen collected from Hogg's plant in 1873 was discovered in in 2006 and its examination strongly suggests that the introduction consisted of at least one male and one female plant. Thomas Hogg's independent introduction of the species from Japan could well explain the higher levels of genetic diversity displayed by Japanese knotweed populations in eastern North America compared to those in Europe.

Aplectrum hyemale and Tipularia discolor are wintergreen orchids native to the eastern and central United States. Each produces a single leaf in late fall that persists through the winter and senesces in early spring. Both species occur in scattered patches in the understory of deciduous forests, and although they overlap in range and often co-occur in the landscape, their habitat and photosynthetic potential have not been compared directly. In this study we examine the relative abundance of A. hyemale and T. discolor in western North Carolina and quantify habitat characteristics and levels of leaf chlorophyll for each species. We conducted broad-scale surveys (walkabouts) of seven sites in Pisgah National Forest during the winter and collected habitat data in 26 patches of each species in one mesic forest. Both species shared similar habitat attributes at this site (plants located ∼ 2 m from overstory trees of similar diameter in ∼ 45% sunlight). However, across all sites, T. discolor was three times more abundant than A. hyemale, more likely to occur in large patches (> 20 plants), and more consistently distributed across a range of slope aspects. In contrast, A. hyemale occurred most often on slopes facing 91–180°, and at elevations > 750 m. Whereas A. hyemale was most often associated with Liriodendron tulipifera overstory trees, T. discolor was often in close proximity to Quercus spp. as well as L. tulipifera. Leaf chlorophyll was twice as high in A. hyemale, which could support differences in photosynthetic strategies, or reflect differences in leaf size and morphology.

Pinus palustris Mill. (longleaf pine) ecosystems support a diversity of rare plants and animals, but have been substantially degraded by historical human impacts. A suite of natural disturbances influence development and succession in P. palustris ecosystems, ranging from frequent, low-intensity events such as surface fires to infrequent, catastrophic events such as hurricanes. Like hurricanes, tornadoes may produce catastrophic winds that create canopy openings necessary for regeneration of P. palustris and other shade-intolerant species. Despite their pervasiveness in some P. palustris ecosystems, we know relatively little about the impacts of tornadoes. Our study, conducted July–August 2015 in fire-restored P. palustris stands of the Alabama Fall Line Hills, applied a nested sampling design to compare dead trees, live trees, saplings, seedlings, and herbaceous plants in plots either undisturbed or directly impacted by an Enhanced Fujita scale 3 tornado on April 27, 2011. Most wind-killed trees were uprooted or snapped, and consisted primarily of large P. palustris stems. Pinus palustris persisted, however, with increased relative densities in the tree, sapling, and seedling strata of wind-disturbed neighborhoods. The relative densities of Quercus L. (oak) trees and saplings also increased. Combined with an herbaceous stratum composition typical of other restored P. palustris stands, desirable woody species recovery indicated that the stands surveyed here were resilient to the 2011 tornado. Contrary to expectations, the tornado reduced woody stem diversity and herbaceous cover. These results may serve as a benchmark for tracking species-specific changes in P. palustris communities and guide management decisions, including those designed to promote native forest diversity.

We studied the floristic composition, the abundance, and the vertical distribution pattern of the vascular epiphyte community of a woodland savanna forest fragment in the municipality of Bauru, State of São Paulo, southeastern Brazil. We sampled 533 specimens of vascular epiphytes of 17 species from 12 genera and four families: Bromeliaceae, Cactaceae, Orchidaceae, and Polypodiaceae. The families Bromeliaceae and Polypodiaceae were the richest in species and the most abundant. We observed that most epiphyte individuals concentrate in the high-trunk stratum. We attribute the low species richness and low abundance of epiphytes observed in the woodland savanna to the existence of a climatic seasonality characterized by a season of low rainfall that limits colonization by a large number of species and individuals. We believe that humidity and solar irradiation determine the vertical distribution pattern of epiphytes in the woodland savanna.

Twenty-one species of tall, long-lived columnar cactus species show extensive bark coverage (epidermal browning) in the Americas. Each species shows more bark coverage on equatorial-facing surfaces than on polar-facing surfaces. In addition, controlled experiments with supplemental UV-B irradiation show the initial stages of bark coverage. These two facts suggest that UV-B irradiation is the cause of sunlight-induced bark coverage. This sunlight-induced bark leads to premature morbidity and mortality. Saguaro cactus (Carnegiea gigantea (Engelm.) Britton & Rose) of southern Arizona is the most researched cactus species with regard to this bark coverage. The current effort focused on bark coverage rates on 12 cactus surfaces at 1.7 m height above ground by comparing logistic curves of relative bark coverage among stem surfaces. Logistic curves have been used to document progress of many diseases in humans. In this study, logistic curves were best fit to data with least squares analysis in all cases to build a model of bark formation on cactus surfaces. Percentages of bark formation were estimated on south-, east-, west-, and north-facing crests and the two associated troughs of each crest on each cactus plant, data from the 12 surfaces were obtained for analysis. Because south-facing crest surfaces exhibited bark formation before other surfaces, bark coverage rate on the 11 other surfaces was compared with bark coverage on south crests. Bark formation occurred on east and west crests about 3 yr after bark formation on south crests, and bark on north crests occurred about 8 yr after bark formation on south crests. On all surfaces, bark formation on troughs occurred after bark formation on crests. On average, the delay in bark coverage on south-, east-, west-, and north-facing troughs was 6−7, 3−5, 5–8, and 4−6 yr, respectively, compared with their respective crests. Young saguaros do not exhibit bark coverage. However, once bark coverage began on south-facing crests at 1.7 m above the ground, on average all stem surfaces at 1.7 m had complete bark covering within 45 yr. This rate of bark coverage is consistent with mortality rates of more than 2% per year for the past several decades among adult saguaros.

The taxonomic delimitation and generic placement of Santessoniella crossophylla (Old Gray Crosslobes), a cyanolichen endemic to eastern North America, are revisited based on newly generated nrITS and mtSSU sequences. A population from Nova Scotia whose identification as S. crossophylla has been questioned is confirmed as belonging to the species. The monospecific genus Rockefellera is introduced to accommodate lichens ascribable to S. crossophylla in light of molecular results herein presented. The new name honors the Rockefeller family for their century-long support of North American conservation efforts, particularly with respect to national parks.