Journal of the Torrey Botanical Society

Online ISSN: 1095-5674
Publications
Article
Includes bibliographical references. Thesis (M.S.)--University of New Hampshire, 1990.
 
Article
Elliott, K. J. and J. M. Vose (Coweeta Hydrologic Laboratory, Southern Research Station, USDA Forest Service, Otto, NC 28763). Effects of prescribed burning on shortleaf pine (Pinus echinata Mill.)/mixed-hardwood forests. J. Torrey Bot. Soc. 132: 236-251. 2005.-We examined the effects of a single dormant season fire on overstory and understory species diversity and composition and tree seedling regeneration patterns the first and second years following a prescribed burn in the Conasauga River Watershed of southeastern Tennessee and northern Georgia. We asked: Can a single dormant season fire initiate a trajectory of overstory and understory species change consistent with restoring Pinus echinata/mixed-oak/bluestem (Andropogon gyrans and Schizachyrium scoparium)-grass community types? Six sub-watersheds (similar in vegetation, soil type, stream size, and disturbance history) were located within the Conasauga River Watershed; four of the sites were burned in March 2001, and two sites were designated as controls. Within each site, vegetation was measured in layers: the overstory layer (trees > or = 5.0-cm DBH), the midstory layer (woody stems < 5.0-cm DBH and > or = 0.5 m height), and the ground flora layer (woody stems < 0.5-m height and all herbaceous species). All plots were sampled before the prescribed burn (Sept. 2000) and after the burn in July of 2001 and 2002. Consistent with the goals of the land managers, all the prescribed fires resulted in low-to-moderate intensity and low severity fires. However, we found no significant change in overstory, midstory, or ground flora species diversity after burning. We found no regeneration of P. echinata seedlings after the prescribed fire. Although fire reduced basal area of woody species in the midstory, prolific sprouting from hardwoods resulted in higher density of fire-sensitive hardwoods such as Acer rubrum, Oxydendrum arboretum, and Nyssa sylvatica. Density of Pinus strobus, an undesirable species, was reduced by 20% and its basal area was reduced by 50% after the burn. Overstory mortality occurred in small size class hardwoods as a result of the fire, but most of the mortality occurred in P. echinata and P. virginiana Miller due to infestation with pine bark beetles. The prescribed fires were not of sufficient intensity to: reduce overstory basal area, prepare a seedbed for successful pine germination, affect diversity of any of the vegetation layers, or promote A. gyrans and S. scoparium recruitment. Thus, additional fire treatments or a combination of fire and thinning treatments will be necessary to restore these ecosystems to P. echinata/mixed-oak/bluestem grass community types.
 
Article
Bloodroot Valley, in central Staten Island, south-eastern New York State, has unusual vegetation. It is a highly disturbed area in which serpentinite rubble has been deposited on till-covered serpentinite bedrock. Bloodroot Valley is reputed to contain the only wild, albeit augmented, population of Sanguinaria canadensis found on Staten Island. The hypothesis of the study was that variation in observed plant associations would correlate with variations in soil properties. This study compared two distinct vegetative patterns on opposing slopes, existing within meters of each other, and each associated with different soil properties. Human disturbance in one area of Bloodroot Valley has fostered a unique soil condition that reflects a blend of features of serpentinite soils, anthropogenic calcium deposits and river floodplains. Vegetation on the west slope in Bloodroot Valley contains neither "serpentinite flora" nor flora typical of the adjacent mixed oak forest, but rather, a floodplain type plant association with Hydrophyllum virginianum as dominant.
 
Article
The magnificent stands of old-growth trees that characterize the forests of western North America depend on periodic fires for their creation or survival. Deprived of that essential disturbance process eventually they die, leaving an overcrowded growth of smaller trees vulnerable to intense blazes and epidemics of insects and disease. In Mimicking Nature's Fire, forest ecologists Stephen Arno and Carl Fiedler present practical solutions to the pervasive problem of deteriorating forest conditions in western North America. Advocating a new direction in forest management, they explore the promise of "restoration forestry" -- an ecologically based approach that seeks to establish forest structures in which fire can once again serve as a beneficial process rather than as a destructive aberration. The book begins with an overview of fundamentals: why traditional forestry tried to exclude fire from forests, why that attempt failed, and why foresters and ecologists now recognize the need for management based on how natural ecosystems operate. Subsequent chapters consider: how fire's historic role provides a foundation for designing restoration strategies; why a hands-off approach will not return forests to their historical condition; how management goals influence the strategies used in restoration forestry. The second part of the book presents case studies of restoration projects in the western United States and Canada, representing different forest types, different historic fire regimes, and contrasting management goals. For each project, the authors describe why and how the project is being conducted, profile forest conditions, and describe methods of treatment. They also report what has been accomplished, identify obstacles to restoration, and offer their candid but understanding evaluation. Mimicking Nature's Fire concludes by placing restoration forestry in the broad context of conserving forests worldwide and outlining factors critical for its success.
 
Article
Very little is known about how emerald ash borer will affect hardwood swamps, which often have a large ash component compared to upland forests. The aim of this research project was to investigate the current status of ash swamps that have become infested with emerald ash borer and make predictions about the future state of these forests. We surveyed three hardwood swamps in southern Michigan that varied in the amount of ash present (12.4%-58.8% basal area), which appears to affect how these communities will change as a result of emerald ash borer. Our analyses indicate that the two swamps with the least amount of ash will likely experience a proportional increase in surrounding trees, while structure of the site with the most ash will be altered in the future and may transition to a forest that is strongly influenced by shrub-like individuals as well as non-ash canopy trees.
 
Twenty-six Symphyotrichum georgianum populations sampled across the species' range.  
Results of analysis of molecular variance (AMOVA; Excoffier 2006: http://lgb.unige.ch/arlequin/) based on 36 single nucleotide polymorphic (SNP) markers from 26 Symphyotrichum georgianum populations.
Genetic relationships among 26 Symphyotrichum georgianum populations roughly follow geographic proximity. Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis using Nei's genetic distances based on 36 single nucleotide polymorphic marker profiles. Alabama (filled square), Georgia (open square), North Carolina (filled circle), and South Carolina (open circle).  
Average (6 1 SE) percentage polymorphic loci and average gene diversity for small (, 100 stems) and large (. 500 stems) Symphyotrichum georgianum populations from Alabama (AL), Georgia (GA), South Carolina (SC), and North Carolina (NC).  
Article
Single nucleotide polymorphic (SNP) markers were used to characterize the genetic structure of Symphyotrichum georgianum (Alexander) G.L. Nesom, known more commonly as the Georgia aster, from 26 populations across the species' range. This species is considered vulnerable (G3) and was a candidate for listing under the Endangered Species Act. We sampled large (> 500 stems) and small (< 100 stems) populations from across the entire range for the species. Next generation sequencing was used to assess 36 SNP markers for pooled population samples, consisting of equal amounts of genomic DNA from 30 individual stems sampled across each population. Most of the genetic variation was partitioned within and less among populations, which is consistent with perennial outcrossing species. There was a significant (r = 0.506, P < 0.001) positive association between geographic distance and genetic distance among populations, indicating increasing genetic distance (genetic dissimilarity) with increasing geographic distances between populations. There was no statistically significant difference in genetic diversity between large and small populations, but trends were observed. The Georgia and North Carolina large populations were more genetically diverse than the small populations, while the small populations were more genetically diverse than the large populations in Alabama and South Carolina. Symphyotrichum georgianum is an outcrossing perennial aster with a rhizomatous growth habit. Extensive clonal growth could account for the low genetic diversity estimates from large populations; however, quantifying the extent of clonal growth within sites is beyond the scope of the current study. There was no association between genetic diversity measures and seed fill or germination rates. Additional fine scale genetic structure studies are underway to address the extent of clonal growth in these remnant populations and how that may affect viable seed production.
 
Change in area of scrub gaps after creation by burn piles. Area of scrub gaps (N ¼ 12) from 1993 to 2003 (116 mo after the burn). Area remaining open declined as Area ¼ 53.209-0.337 (time), r ¼À0.626, P , 0.001. Seven of these gaps burned in 2004. Area of four scrub gaps from 1993 to 2007 (163 mo after the burn). Area remaining open declined as Area ¼ 47.782-0.304 (time), r ¼À0.70, P , 0.001. These gaps did not burn in 2004. Error bars indicate 1 SE.
Plant groups in the Shiloh scrub matrix and gaps.
Changes in area of gaps burned a second and third time. (A) Area of seven gaps created in 1993 and burned again in 2004. Error bars indicate 1 SE. After the first burn, gap area declined as Area ¼ 50.624-0.311 (time), r ¼ À0.678, P , 0.001; after the second burn gap area declined as Area ¼ 37.919-0.699 (time), r ¼ À0.565, P ¼ 0.002. (B) Area of four gaps created in 1993 and burned in 2004 and 2008. After the first burn, gap area declined as Area ¼ 48.330-0.348 (time), r ¼À0.752, P , 0.001; after the second burn, gap area declined as Area ¼ 41.101-0.828 (time), r ¼À0.752, P ¼ 0.001; after the third burn, gap area declined as Area ¼ 38.8050.734 (time), r ¼ À0.686, P ¼ 0.001.
Article
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.
 
Profiles of species-level parameters from edge to interior zones in three tallgrass prairie preserves in eastern Illinois. Shown are trends from noncrop-edge zones (solid line) and crop-edge zones (dashed line). Each point represents average among transects (n ¼ 6) per site and sites (n ¼ 3). Error bars are SE.
Functional group differences between edge and interior zones recorded from three remnant mesic tallgrass prairies in east-central Illinois. (a) Mean percent cover for each functional group contrasting the baseline edge and interior zones. (b) Proportion of cover for major functional group categories contrasting baseline data from edge and interior zones.  
Change in cover among functional groups in repeated samples 5–6 yr following baseline, contrasting edge and interior zones in three tallgrass prairie remnants in east-central Illinois. (a) Change in percent cover. (b) Change in proportion of baseline cover.  
Results from indicator species analysis for functional groups examining zone affiliation (edge vs. interior zones).
Article
To evaluate the floristic sustainability of three small, isolated tallgrass prairie remnants, spatial and temporal patterns of species and functional group (FG) composition, richness, diversity, and dominance were examined to determine whether there was divergence between edge (outer 10 m) and interior zones. These remnants, all protected and managed nature preserves, are rectangular in shape and range in area from 1.29 ha to 1.77 ha; each is bordered by cropland and unmanaged or mowed ruderal grassland. A stratified sampling design was established using permanently marked transects oriented perpendicular to the long axis of each site. Vegetation data were collected in 50 cm × 50 cm quadrats along each transect; prairies were resampled 5–6 yr following baseline data collection. The null expectations were no differences between edge and interior zones, no differences between edge type (crop and noncrop), and no change over time. Results from linear mixed-effects models identified significant differences between edge and interior zones for native species density, native diversity, dominance, percent native cover, and measures of floristic quality; however, there were no time differences and no significant zone × time interactions. Distance from edge to peak levels of species density and diversity was about 15 m yielding core habitats 43% to 50% of remnant size. Beta diversity based on species presence was greater in edge zones compared to interior zones, and declined slightly in repeated samples. Functional group diversity was lower in edge zones compared to interior zones and declined significantly in the repeated samples. Functional groups with significant affiliation to the edge zone were nonnative grasses, woody vines, ferns/allies, and nonnative legumes; FGs affiliated with the interior zone were C4 grasses, hemiparasites, nitrogen-fixing shrubs, and perennial forbs. One site was sampled three times following 5–6 yr intervals and there were no additional within-site differences in the third sample. These prairies support a rich diversity of native species; however, patterns suggest they are effectively smaller than they appear with a trend of declining functional diversity.
 
Article
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.
 
Article
The Exhibition's website defines botanical art as being identifiable to at least the genus level, and all of the catalogued works, regardless of medium, share an attention to detail. Many images in the Catalogue convey the flora so accurately that they could be mistaken for photographs. Some are surreal because of their vibrancy, like the specimen of Wisteria painted by Margaret Joyce Wilson. All of the pieces demonstrate an art form aesthetically pleasing to even nonbotanical individuals, but one that also communicates the essence of these species in a scientifically informative way. Like the works being illustrated, the Catalogue successfully marries art with information, which is provided in concise captions with each image and includes the plant's binomial, the artist's name, techniques and media used, and the size of the original work.
 
Article
Climate change has altered the phenological timing of plants across the globe. These changes are especially concerning for plants with small distributions and in unique ecological sites. Here, we examined changes in phenology with respect to temperature and year over a 125-yr span for 12 herbaceous species native to the lowlands of the New Jersey Pine Barrens using herbarium specimens and citizen science observations. Among early summer flowering species, flowering occurred on average 1.42 days/C earlier in the spring of the corresponding year. Early summer flowering species flowered at an average rate of 0.071 days/yr earlier over the 125-yr study period, whereas no significant change was detected in flowering times of late summer species. Exploration of a set of sister taxa with differing range sizes resulted in no detectable shifts in phenology, which may be explained by evolutionary relatedness or flowering in late summer. The variation in responses to species in the New Jersey Pine Barrens may alter the balance of this ecosystem in the future, as some species respond to changing temperatures, whereas others do not. These results add to a growing body of work suggesting that variations in temperature due to climate change are affecting plant phenology.
 
Article
Trillium grandiflorum is a widely distributed, non-clonal, long-lived, white-flowered perennial herb. We examined the pollination biology and self-compatibility of Trillium grandiflorum in five populations distributed across northern Wisconsin and the western Upper Peninsula of Michigan. Self-pollination was almost entirely ineffective in producing seeds in all populations, suggesting strong self-incompatibility. Natural seed set varied slightly across populations, with an average of 71% of ovules fertilized per fruit. At the population level, seed set was not limited by receipt of pollen. At the plant level, seed set per flower first increased, then decreased in response to an increasing density of flowering plants within 2 m. This suggests that neighboring flowers facilitate pollinator visitation at low densities then compete for visits at higher densities. Observed pollinator visitation rates support this interpretation. The presence of self-incompatibility and the absence of clonal spread could make Trillium grandiflorum vulnerable to disruptions in pollinator service.
 
Article
Recent studies have demonstrated substantial changes in the composition and structure of forests in northeastern North America following Euro-American settlement. Especially striking are the “homogenization” of tree species composition across the region and a steep decline in conifer abundance. However, the presettlement distribution and subsequent changes for individual species at a finer scale are not well documented. In this study, we examine the presettlement and current distribution of Pinus strobus L. (eastern white pine) on specific habitats in the northern hardwood forest of Wisconsin by re-surveying 201 nineteenth-century land survey corners. The status of P. strobus regeneration was evaluated in the second-growth forests, as well as in a set of remnant old-growth stands on comparable sites. P. strobus occurred across a broad range of habitats in the presettlement landscape, including highly productive, mesic sites where it rarely occurs in the modern forest. Former white pine-hemlock-hardwood forests most often transitioned to Acer or Populus dominance, matching compositional transitions of the overall landscape. Pinus strobus was retained at ∼28% of presettlement locations, but a large majority of these were dry-mesic or lower-productivity mesic/wet-mesic sites. The modern distribution of P. strobus in hemlock-hardwood forests appears to be strongly influenced by historical factors, rather than site limitations. Pinus strobus regeneration was rare across habitats in the modern landscape; thus, the habitat differences that led to differential retention may not be as influential on its future distribution. Our findings indicate that restoration of P. strobus to a wide variety of habitats, including high-productivity mesic sites, is supported by historical information and that active restoration is probably necessary across a spectrum of habitats.
 
Flora on the old High Line, July 2019.
Summary of lichens, bryophytes, and vascular flora of the High Line, New York City, NY in 2002 and 2019. Those from 2019 are in parentheses. Total values are for vascular plants.
Article
This study compares the lichen, moss, and vascular plant species found on the abandoned High Line rail line in 2002 with those found on a three-block remnant of the High Line between 30th and 33rd Streets and 12th Avenue in 2019. One hundred fifty-five species were identified in 125 genera belonging to 47 families in the 2002 study. The 2019 study identified 79 species within 68 genera belonging to 32 families. Ten lichens were identified in 2019; four were identified in 2002. The number of mosses found in 2019 remained the same (six species); four species were new to the study area, and four species found in 2002 were not relocated. The loss of vascular plant species on the old High Line in 2019 is a function of its reduced size, a three-block remnant of the original site. The increase in lichen diversity might reflect improved air quality and continued lack of disturbance to suitable substrates at the remnant site.
 
Detrended correspondence analysis of woody overstory species from the Fernow Experimental Forest stratified by measurement period. Results are based on relative requency of stems only for all time periods since the 1856 survey data did not include tree size.
Diversity (A) and evenness (B) of stands within the Fernow Experimental Forest with respect to the year of observation. Results are based on relative frequency of stems for all time periods since the 1856 survey data did not include tree size. Quadratic response coefficient derived from a standardized independent variable, i.e., xi = xi -x.
Detrended correspondence analysis of second-growth understory species composition from the Fernow Experimental Forest (Compartment 8 and vicinity) stratified by silvicultural treatment. Results are based on IV's which combined relative frequency and relative basal area of individual species.
Understory richness (A) and diversity (B) stratified by silvicultural treatment. Results are based on IV's which combined relative frequency and relative basal area of individual species.
Article
This study examined the composition of woody species in a mixed mesophytic forest in the central Appalachian region with respect to both time and different disturbance regimes. Species composition and diversity were assessed from 1856 to 1997 on a tract of land that currently is part of the Fernow Experimental Forest in north-central West Virginia. Additionally, the effect of different silvicultural disturbances are described using inventory data from four silvicultural demonstration areas initiated in 1948. These areas included a commercial clearcut, diameter-limit harvesting, single-tree selection, and an area that has not been artificially manipulated since initial logging around the turn of the century (ca 1907). Witness tree data from early land surveys (1856 and 1915) conducted in the same watershed were used to gain some insight into species frequency prior to and after initial logging. A forest inventory conducted in 1922 provided a more detailed description of the vegetation in the vicinity of the post-1948 stand data. The Shannon-Weiner Diversity Index was calculated based on species importance values for all time periods and management activities. Detrended correspondence analysis was used to assess differences in composition related to time and management activity. Data from old-growth (1856), early second-growth (1915 and 1922), and more mature second-growth stands were well separated in ordination space. A decline in species diversity from a high in 1922 to a low in 1997 appears to be driving this separation. Diversity declined primarily due to a reduction in evenness, which was significantly correlated with increasing importance of Acer saccharum. Relative A. saccharum importance is increasing in both the overstory and understory for all disturbance regimes. The increasing dominance of this species with time, regardless of stand age or disturbance regime evaluated, may be unprecedented and suggests new silvicultural techniques are needed to maintain the diversity of central Appalachian forests.
 
Article
A century of dramatically altered disturbance regimes has likely changed patterns of forest regeneration, with potential detrimental consequences for the future diversity, composition, and function of late-succession and old-growth forest stands. We quantified the diversity and composition of tree species in the canopy and understory layers of 19 late-successional and old-growth forest stands in Pennsylvania to evaluate the consequences of existing regeneration patterns for the future composition of these communities. Despite relatively high canopy diversity across all stands, the understory of all stands was comprised of a small homogeneous subset of the canopy species. In addition, understory layers had lower species diversity than their respective canopies and showed a significant lack of species intermediate in shade tolerance. Oak species, which often require fire to regenerate, were common in the canopy of 12 stands, but nearly absent from the understory layer of all stands. Our findings are consistent for late-succession and old-growth stands located across a large geographic area of Pennsylvania and across stands of varying sizes, canopy species composition, and location in different physiographic provinces. These findings suggest that disruptions to historical disturbance and browsing regimes play a strong role in this dramatic homogenization of understory species composition. In the absence of large-scale disturbance, these stands will become relatively depauperate and composed of a homogeneous subset of species that are simultaneously shade-tolerant, browse-tolerant, and fire-intolerant.
 
Article
Archival information was searched for evidence of lightning strikes and subsequent ignitions in Pennsylvania forests. Between 1912-1917, twenty-eight different tree species were struck by lightning 2553 times igniting 77 individual trees. These data probably underestimate the number of ignited fires due to rugged terrain, inefficient fire reporting, and minimal fire control resources of this early era. Lightning strikes occurred most often between June-August, peaking in July with 877 strikes. These data provide direct evidence that lightning strikes and tree ignitions occur relatively frequently in Pennsylvania forests. Recent data provide substantial evidence for large areas burned by lightning ignitions during drought years in the past thirty-seven years.
 
Article
This study documents changes in the distribution of non-native woody species from 1938 to 1999 within 30 forests of a $54\>km^2$ landscape in Monroe County, New York. Within these forests, the mean number of exotic species increased nearly three-fold from 1938 to 1999, and two species not naturalized within the landscape in 1938, Lonicera morrowii and Rosa multiflora, had become widespread by 1999. In 1999, the most abundant exotic was Lonicera morrowii, which had greater cover within forests on wetter portions of the landscape where much of the surrounding agricultural land had been abandoned. Though exotics accounted for < 10 % of relative cover within the shrub layer and < 1 % of the tree layer, their cover was higher in portions of some forests, especially near edges. In 1999, six species had covers > 25 % within patches $> 100\>m^2$: Acer platanoides, Crataegus monogyna, Ligustrum vulgare, Lonicera morrowii, Robinia pseudoacacia and Rosa multiflora. These species in particular may represent on-going invasions that could alter this landscape's forested habitats.
 
Comparison between plant species diversity of Pelham Bay Park found in 1946-1947 by H. E. Ahles and the 1994-1998 flora.
Article
This vascular flora of Pelham Bay Park, Bronx County, New York is based on collections made by H.E. Ahles in 1946-47 and by the authors from March of 1994 through October of 1998. Altogether, 123 families, 471 genera and 956 species are reported here. Of these 956 species, 583 (61.0%) are native, 321 (33.6%) non-native and 52 (5.4%) either planted or introduced and not spreading to any degree. The largest families were the Asteraceae (120 species) and the Poaceae (106 species), and the largest genera were Carex, Polygonum and Aster. The park's current flora is analyzed by habitat and four plant communities are described and discussed. Most of the extant plant species diversity occurs in two habitats: 255 species were found primarily in the woodland community, and 288 species usually occurred in the grassland/meadow community. According to current criteria in New York, 27 native species collected in 1994-98 are considered uncommon, rare, threatened or endangered in the state. The most pernicious non-native species that occur in PBPK are: Acer platanoides, Alliaria petiolata, Ampelopsis brevipedunculata, and Rhamnus frangula. The future of the remaining natural areas of Pelham Bay Park will depend upon the degree biologists make people aware of the significant plant species diversity remaining in New York City's second largest park.
 
Article
Studies of the growth, survival, and sex ratios of dioecious species have been predominantly short-term. This research investigated growth rates, survivorship, and sex ratios among cohorts of Juniperus virginiana L. from 1963 through 2000. Males (M) and females (F) in six old-fields of different ages on the New Jersey Piedmont were analyzed, starting with the initial data on height and sex expression collected by John Small on labeled recruits from 1963 through 1976. These plants were relocated and censused during the summer and fall of 2000. No changes in sex expression were recorded between 1976 and 2000. The overall sex ratio was almost 1:1 (333 M, 332 F); only one of the fields showed a significant departure from 1:1. Males grew slightly, but significantly, faster in height than females, but relative growth rates dropped by approximately 50% for both males and females once they became reproductive. Female trees were on average 23 cm taller (and older) than males at first reproduction. Heights in those males and females surviving to 2000 were not significantly different. There was no effect of an individual's sex on its likelihood of dying, but plants that became established later were shorter, often non-reproductive, and had an increased risk of mortality. These long-term results strongly support genetically-determined sex ratios and a lack of major differences between males and females in growth rates and survival, which had been suggested by single-year studies elsewhere in the species' range.
 
Article
In recent years, the eastern United States has experienced little tree mortality due to insects; nonetheless, the emerald ash borer threatens future composition of the ash genus, which is distributed in the eastern and central United States. Given probable decline of the ash genus due to the emerald ash borer, I assessed recent range dynamics of F. pennsylvanica Marsh. (green ash), F. americana L. (white ash), F. nigra Marsh. (black ash), and Populus deltoides Bartr. ex. Marsh. (eastern cottonwood), one of the species that has been replaced by F. pennsylvanica. I compared current and oldest available USDA Forest Service Forest Inventory and Analysis surveys. Fraxinus pennsylvanica expanded 32 million ha in range (≥ 0.5% of total species composition, or total number of stems) during approximately a mean difference of 29 years. Moreover, F. pennsylvanica increased 6 million ha where it was present at ≥ 10% of total species composition. Fraxinus americana increased 15 million ha in range but decreased 7.5 million ha where it was present at ≥ 10% of composition. Fraxinus nigra remained stable in range and generally increased in composition. Similarly to F. americana, P. deltoides increased in range 16 million ha but decreased 11 million ha where it was present at ≥ 10% of composition. There were no indications of mortality due to emerald ash borer. Throughout most of their ranges, ashes were a minor species within diverse and dense forests of the eastern United States. The greatest impacts of emerald ash borer should occur in the central United States, where F. pennsylvanica was a major species of riparian woodlands and provides structure to dependent wildlife and plants and where emerald ash borer recently has been discovered.
 
Article
This study spans a period of 25 years, 1973-1998. It combines present data with findings reported in 1978 and 1979. Vascular plants growing along 10 miles of the Bronx River Parkway Reservation between Bronxville north to the Kensico Dam Plaza in Valhalla are recorded. Plants are categorized into five major groups: Vascular Cryptogams, Gymnosperms, Monocotyledons, Woody Dicotyledons and Herbaceous Dicotyledons. Reported are 128 families, 387 genera, and 785 species of which 279 or 35.5% are nonindigenous. This finding is 5.5% higher than the 30% alien species reported for New York State. Invasive aliens remain very constant; they represented 10.5% of the listed species in 1978 and 10.6% 20 years later. Moreover, 91.7% of these foreign invaders have been on the Reservation for at least 25 years. Nevertheless there is great concern regarding their presence; they tend to displace local flora, change ecosystems, upset biodiversity and need to be controlled.
 
Article
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.
 
Article
Twenty one noteworthy species of vascular plants are reported from the Torrey Range, encompassing southeastern New York, northern New Jersey, and southwestern Connecticut: Amaranthus pumilus, Arethusa bulbosa, Aristolochia serpentaria, Bolboschoenus maritimus ssp. paludosus, Bouteloua curtipendula, Campanula glomerata, Cardamine impatiens, Chimaphila umbellata ssp. cisatlantica, Cyperus retrorsus, Diospyros virginiana, Gaylussacia dumosa, Glaux maritima, Heracleum mantegazzianum, Hydrocotyle verticillata, Hypericum hypericoides ssp. multicaule, Polygala lutea, Pycnanthemum torrei, Sedum sexangulare, Spergula morisonii, Tropaeolum majus, and Uvularia puberula. Fourteen species are listed as rare in either New York, New Jersey, or Connecticut, and one is on the federal list of threatened species. Four species are new records for the Torrey Range. Two species found on Staten Island had not been reported from there since the 1860s, and three species from Long Island are re-located populations from the 1920s and 1930s. Two species have become, or have the potential to become, invasive weeds.
 
Article
Twenty one noteworthy species of vascular plants are reported from the Torrey Range, encompassing southeastern New York, northern New Jersey, and southwestern Connecticut: Amaranthus pumilus, Arethusa bulbosa, Aristolochia serpentaria, Bolboschoenus maritimus ssp. paludosus, Bouteloua curtipendula, Campanula glomerata, Cardamine impatiens, Chimaphila umbellata ssp. cisatlantica, Cyperus retrorsus, Diospyros virginiana, Gaylussacia dumosa, Glaux maritima, Heracleum mantegazzianum, Hydrocotyle verticillata, Hypericum hypericoides ssp. multicaule, Polygala lutea, Pycnanthemum torrei, Sedum sexangulare, Spergula morisonii, Tropaeolum majus, and Uvularia puberula. Fourteen species are listed as rare in either New York, New Jersey, or Connecticut, and one is on the federal list of threatened species. Four species are new records for the Torrey Range. Two species found on Staten Island had not been reported from there since the 1860s, and three species from Long Island are re-located populations from the 1920s and 1930s. Two species have become, or have the potential to become, invasive weeds.
 
Article
Twenty-four noteworthy species of vascular plants are reported from the Torrey Range, encompassing southeastern New York, northern New Jersey, and southwestern Connecticut: Acalypha australis, Carex arctata, Carex typhina, Corallorhiza trífida, Corydalis incisa, Cyperus polystachyos var. texensis, Cypripedium parviflorum var. makasin, Dryopteris celsa, Froelichia floridana, Galium boréale, Houstonia pusilla, Isotria medeoloides, Juglans ailantifolia, Juncus brachy carpus, Kyllinga pumila, Nymphoides peltata, Oldenlandia uniflora, Phlox divaricata, Platanthera pallida, Pycnanthemum verticillatum, Ranunculus pusillus, Schoenoplectus mucronatus, Stylophorum diphyllum, and Trichostema setaceum.
 
Article
Twenty noteworthy species of vascular plants are reported from the Torrey Range, encompassing southeastern New York, northern New Jersey, and southwestern Connecticut: Actinidia arguta, Carex kobomugi, C. merritt-fernaldii, Crocanthemum propinquum, Cyperus acuminatus, C. difformis, C. echinatus, C. pseudovegetus, Euphorbia serpens, Geum vernum, Hedeoma hispida, Hydrangea paniculata, Hydrocharis morsus-ranae, Juncus diffusissimus, Kalopanax septemlobus, Muhlenbergia asperifolia, Rotala ramosior, Scirpus pallidus, Tripidium ravennae, and Viola bicolor.
 
Article
DIGGINS, T. P. (Department of Biological Sciences, Youngstown State University, One University Plaza, Youngstown, OH 44555). A 300-year successional sequence in an eastern United States riparian hardwood forest. J. Torrey Bot. Soc. 140: 65-88. 2013.-Hardwood-dominated riparian forest was surveyed in 83 quadrats on 3 floodplains, 11 lower terraces, and 8 upper terraces along 11 km of Zoar Valley Canyon, a minimally disturbed segment of 5th-6th order Cattaraugus Creek in western New York State, USA. Increment core-based stand ages from 8 to >300 years constituted the longest middle-order riparian sequence yet studied in the East. Comparisons of aerial images starting in 1929 with present-day increment cores indicated trees have reached breast height and persisted on recent lower terraces within at most 627 years after deposition, suggesting landform age and type associated primary succession rather than flood-regime driven secondary succession or maintenance of early seral stages. In 2009, the second largest flood since 1940 caused only modest damage even to floodplain stands, supporting this premise. Regressions of stand characteristics on age across the 300-year sequence revealed logarithmic increases in tree diameter and height, stand basal area, and shade tolerance as succession has progressed. Non-metric multidimensional scaling (NMDS) ordination of stand characteristics and species distributions further revealed coherent successional gradients, including affinity vs. divergence among species of varying life history traits; e. g., an association between late-seral Acer saccharum and Fagus grandifolia and their divergence from pioneering Populus deltoides and Salix nigra. It also revealed a convincing association of biotic variables with a directional and strongly discriminated ordination distribution of landform types of increasing maturity; i.e., geomorphic patterns. Successional trends eventually leveled off beyond similar to 150-200 years' stand age, suggesting a dynamic equilibrium (perhaps now reflecting a gap-phase and no longer true primary succession) that bears structural, compositional, and aesthetic resemblance to scattered old-growth in the surrounding uplands. It has been questioned, especially in the East, whether riparian succession often proceeds so far, or if hydrologic processes more likely interrupt the progression. In Zoar Valley, where vegetational succession appears to have been generally protected from both natural (flood damage, inundation) and anthropogenic disruption (logging, flow regulation), multi-aged old-growth stages occur on upper terraces throughout the riparian zone.
 
Article
As humans increasingly disturb coastal ecosystems, there is a need to understand the interaction between natural and human-caused disturbances in order to conserve these ecosystems. The goals of this study were: (1) to quantify the size and composition of seed banks in areas of intact maritime chaparral and nearby abandoned roads; (2) to investigate whether a burning regime is necessary to induce germination of the species present in the seed bank; and (3) to compare the seed bank composition with the vegetation in maritime chaparral and abandoned roads. Soil samples for seed bank analysis were collected in October 1996 from seven paired areas of intact chaparral and abandoned roads near Monterey, California. Seed bank samples were subjected to a burn or a control (no burn) treatment, after which germination was monitored in a greenhouse for five months. In spring 1997, vegetation at each area was surveyed. Results of the seed bank study indicated that greater numbers of native plant species and native seeds germinated in intact chaparral compared to road areas, whereas numbers of exotic plant species and seeds germinating were similar in the two habitats. Burning reduced the number of native species and seeds that germinated, and to a lesser extent the number of exotic species and seeds that germinated from the seed bank. In the field survey, intact chaparral areas had greater numbers of native species and greater native cover than roads, whereas road areas had greater numbers and cover of exotic species. Several species were found only in field surveys; in particular, few chaparral shrub seeds germinated from the seed bank. Similarity between the seed bank and vegetation was low in both chaparral and road sites. The results suggest that although many native species of chaparral plants are present in the seed bank, planting of some species may help accelerate recovery in disturbed areas.
 
Article
Lichens are known to be sensitive to changes in air quality. The recent closure of a coal-fired electric generating plant in New Jersey has set up a natural experiment to study the potential rebound of nearby lichen communities. The study area is the Abbott Marshlands, an ecologically important freshwater tidal wetland along the Delaware River, much of which is protected open space. To establish a baseline for future study, a biodiversity inventory of lichens and allied fungi was undertaken in the Abbott Marshlands, yielding 57 species.
 
Article
Study of reproductive patterns of understory species is of great importance because they influence the regeneration dynamics of a forest, and the biogeographic origin of these species will also define their responses to environmental conditions. In this study, we answer the following questions: Are there temporal patterns in the reproductive phenology of understory species? If so, what are the variables that influence them? How do the reproductive patterns of the species differ according to their biogeographic origin? To answer these questions, in the Abies religiosa forest in the Magdalena River Basin, Mexico City, we determined the flowering and fruiting patterns of 55 species using multivariate analyses. Spearman's correlations were calculated between the patterns found and the environmental variables, and Augspurger's synchrony indexes were also calculated. Our results showed three flowering and three fruiting patterns. The correlations showed a significant and positive relationship between flowering and precipitation during the rainy season. A significant and negative relationship was found between dry season fruiting pattern and soil moisture. The highest values of flowering and fruiting for both introduced species and native weeds occurred in different months than for characteristic understory species. Our results suggest strong relationships between reproductive patterns and biotic factors, mainly those related to species growth form and biogeographic origin. This is the first phenology study of this area, and it forms a basis for generation of hypotheses related to forest management and conservation.
 
Article
Both abiotic and biotic factors can influence distributions of invasive plant species, and it is important to understand how such factors contribute to invasion success in order to develop successful management strategies. Microstegium vimineum, known as stiltgrass, is an invasive annual grass in U.S. eastern deciduous forests that can outcompete native understory species, decrease diversity, and prevent the regeneration of native trees. Microstegium is also known to form associations with arbuscular mycorrhizal fungi (AMF), but research has yet to demonstrate whether this association has a role in Microstegium invasion and dominance over native vegetation. We conducted a field survey in invaded and uninvaded habitats across six sites near Louisville, KY, USA, to explore the relative importance of biotic versus abiotic factors in predicting Microstegium abundance and size. Canopy openness was the strongest predictor of Microstegium abundance, followed by soil moisture. Soil nitrogen was the strongest predictor of Microstegium tiller height. Surprisingly, AMF extraradical hyphal abundance and root colonization were not significant predictors of Microstegium abundance or size. In terms of abiotic factors, our results confirm previous studies that have demonstrated that Microstegium grows best in areas with high light and high soil moisture; however, our analysis provides further insight by assessing the relative importance of each of these factors for Microstegium invasion.
 
Article
The species of Xyridaceae are grouped into two subfamilies: Xyridoideae, which includes the genus Xyris, and Abolbodoideae, comprising the genera Abolboda, Achlyphila, Aratitiyopea and Orectanthe. Since the inter-and infra-familiar relationships in Xyridaceae are not yet well established, this study aimed to characterize the morphology and anatomy of vegetative organs and inflorescence axis of Abolboda species in order to assess characters with taxonomic value. Characteristics such as the length and width of leaves, length of inflorescence axes, length of bracts of the inflorescence axis node, number and type of vascular bundles in the mesophyll, presence or absence of bundle sheath extensions in the leaves and shape of the leaf margin are important to delimit the species. The presence of an epidermis with thin-walled cells in the adaxial side and slightly thickened walls on the abaxial side and a hypodermis facing the adaxial side of the leaves differentiates Abolboda from the other genera of Xyridaceae. Partially thickened epidermal cells and nodes on the inflorescence axes are also diagnostic characters of Abolboda. The species of Abolboda have anatomical characteristics that contrast with those of Xyris and others that are similar to those of other genera of Xyridaceae, supporting the division of the family into two subfamilies.
 
Article
Repeated measurements of permanent plots in northeastern U.S. forests provide an opportunity to assess how stand-level changes impact carbon storage in aboveground biomass over time. We used 42 years of census data for >6000 individual trees in a 2.9- ha permanent plot at the Harvard Forest (Petersham, MA, USA) to determine how changes in stand age, structure, and species composition affect carbon storage in aboveground biomass in a Quercus-Acer forest. From 1969 to 2011, the biomass of live trees increased linearly (R2 = 0.99, p = 0.0002), from 150 Mg ha−1 to 268 Mg ha−1, confirming that this ca. 110-year-old stand is still in the aggradation phase of stand development. Over time, a higher proportion of the stand's biomass occurs in large trees. Quercus rubra L. (red oak) accounts for >80 percent of the increase in aboveground biomass due to the rapid growth of dominant stems and low canopy mortality rates. Changes in the biomass of live Acer rubrum L. (red maple) stagnated after 1991, in contrast with region-wide increases, while the proportion of total biomass in subordinate Betula alleghaniensis Britton (yellow birch), Betula lenta L. (black birch), Fagus grandifolia Ehrh. (American beech), and Castanea dentata (Marshall) Borkh. (American chestnut) increased. In the absence of major canopy disturbance we predict that Q. rubra dominance will continue to increase and the stand will steadily accrue carbon for the next century.
 
Top-cited authors
David Foster
  • Harvard University
Oscar E Gaggiotti
  • University of St Andrews
David Alan Orwig
  • Harvard University
Brian C McCarthy
  • Ohio University
K.J. Elliott
  • United States Department of Agriculture