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This study provides quantitative ecological targets for restoring degraded peat-based Carolina Bays in the Carolina Flatwoods Ecoregion. Cluster analysis of vegetation data from three Carolina Bay reference sites in Bladen County, North Carolina, indicated four plant communities present: pond pine (Pinus serotina) woodland, non-riverine swamp forest dominated by swamp gum (Nyssa biflora), high pocosin dominated by evergreen shrubs with scattered pond pine, and bay forest dominated by loblolly bay (Gordonia lasianthus). We classified bay soils according to surface organic layer thickness (OLT) into mineral, histic, shallow organic, and deep organic types. We monitored the water table of each soil type in one bay throughout one growing season. The soil types with corresponding water table regimes were: mineral (9.4 cm mean OLT with a rooting zone water table [RZWT] 39% of the monitoring period), histic (27.5 cm OLT and 76% RZWT), shallow organic (63.9 cm OLT and 84% RZWT), and deep organic (102.5 cm OLT and 57% RZWT). Pearson residual analysis and correspondence analysis revealed that pond pine woodland was positively associated with mineral and histic soils, non-riverine swamp forest with shallow organic soil, bay forest with deep organic soil, and high pocosin with deep organic soil. We concluded that peat-based Carolina Bay restoration in the Carolina Flatwoods Ecoregion should be gauged against reference data which suggests: 1) pond pine woodland be established on mineral and histic soils; 2) non-riverine swamp forest be established on shallow organic soils; and 3) high pocosin and bay forest be established on deep organic soils.
Both native and invasive species that form forest understory layers affect tree seedling establishment worldwide. We compared the density and survival of canopy tree seedlings under and outside patches of the native shrub, Asimina triloba (L.) Dunal (Annonaceae) (pawpaw). We also conducted a manipulative experiment to determine whether above ground or below ground competition was more important in seedling growth and survival. Above ground competition was manipulated by tying back pawpaw stems and below ground competition by trenching the perimeter of the study plots. Overstory density (measured by a canopy densiometer) was greater under pawpaw than outside pawpaw. Tree seedling density was approximately three times greater outside pawpaw than under pawpaw over the range of sites. Seedlings under pawpaw were both younger and shorter than those outside of pawpaw. Survival varied by species. Acer saccharum seedlings were about one and a half times more likely to survive outside pawpaw than under pawpaw. Prunus serotina seedlings were about three times more likely to survive outside pawpaw than under pawpaw. In contrast, pawpaw did not affect the survival of Fraxinus spp. seedlings. The combination of above ground and below ground factors was more important in the survival and growth (measured by biomass) of planted A. saccharum seedlings under pawpaw than either above ground or below ground factors alone. Given that conditions such as elevated deer herbivory and tree diseases may provide opportunities for pawpaw to expand, continued attention to the pawpaw understory is warranted.
Assessing the factors that may contribute to rarity in flowering plants is important in preserving biodiversity. One method of examining these factors is through comparisons of rare species to more common congeners. While these studies are fairly common, most focus on comparisons of intrinsic factors, such as growth and dispersal rates and other physical attributes. In contrast, this study examined the effects of extrinsic factors, specifically herbivory by white-tailed deer (Odocoileus virginianus) and competition with an invasive vine, Lonicera japonica, on a rare forest herb, Trillium reliquum and its more common congeners, Trillium maculatum and Trillium cuneatum. We used a factorial design involving deer exclusion and honeysuckle removal to determine effects on relative growth of rare and common trilliums. We found that a common trillium was more susceptible to herbivory than T. reliquum in one of the three sites with a similar trend in a second site and no effect in the third. Deer also significantly reduced relative leaf area (a measure of growth) for all species, reduced the probability of subadult transitions to reproductives, and increased the probability of non-emergence in two sites. While deer had a significant effect in this study, there was no detectable effect of honeysuckle presence on growth for any species of trillium during this time period. Our results show that the long-term management of white-tailed deer will be important to the conservation of spring ephemeral herbs such as T. reliquum, T. cuneatum, and T. maculatum.
Sweet-scented Indian-plantain, Hasteola suaveolens (L.) Pojark., is a species of special concern in 13 states and jurisdictions in the eastern United States and occurs predominantly in riparian habitats. In the Allegheny National Forest (ANF) of northwestern Pennsylvania, H. suaveolens is considered a species with viability concerns. I surveyed riparian plant communities in the Allegheny River Islands Wilderness (ARIW) of the ANF to provide information on the habitat affinities of H. suaveolens useful for conservation and management needs. Hasteola suaveolens was located within 13 of 42 survey sites on six of the seven islands in the ARIW and occurred in three riparian community types: a floodplain scour community dominated by native herbaceous plants an Acer saccharinum–Platanus occidentalis floodplain savanna community and a Platanus occidentalis–Carya cordiformis (Wang.) K. Koch–Ulmus rubra Muhl. floodplain savanna community. Occurrences of H. suaveolens were largely associated with elevated floodplain geomorphic surfaces having moderately drained to well-drained soils that were located above high energy scour zones.
This study examines the breeding system of Ruellia succulenta (Acanthaceae), an herbaceous perennial found in the pine rockland habitat of southern Florida. Hand pollination treatments were performed on 75 plants, 25 from each of three sites. Treatments applied to test plants included: 1) control (no manipulation), 2) anthers-removed, 3) self-pollinated, and 4) cross-pollinated. The pollination protocol investigated facultative autogamy, apomixis, and self-compatibility. Fruit set and seed number per fruit were recorded. In addition to determining breeding system, the data were used to evaluate inbreeding depression at the earliest life history stages (i.e., fruit and seed set), and to identify the mechanism of self-pollination. Results showed R. succulenta to be fully self-compatible and facultatively autogamous. Plants were unable to set fruit without pollen deposition, indicating the lack of apomixis. There is no evidence of inbreeding depression in fruit set or seed set for the self- vs. cross-pollinated treatments. The mechanism of autofertility appeared to be delayed self-pollination as the corolla abscised and the anthers were dragged past the persistent stigma.
Cross-sections of 36 post oaks (Quercus stellata Wang.) were examined to determine the fire history of a post oak woodland in Hamilton County, Illinois. The 226-year tree ring record contained three distinct periods; a fire era from 1776 to1850 having a mean fire return interval of 1.97 years, a fire-free period from 1851 to1884, and a second fire era from 1885 to 1996 having a mean fire return interval of 1.44 years. The fire-free interval corresponds with the rapid settlement of Hamilton County during 1850–85. The fires between 1770 and 1850 are considered landscape fires associated with Native Americans and/or early European settlers, while those between 1885 and 1996 are thought to be due to burning of local woodlands, a practice that became increasingly less common in the late 20th century. Three post oak cohorts were identified, including 211–224 year-old (217-year mean), 137–151 year-old (144-year mean), and 104–115 year-old (105-year mean) age classes. Post oak recruitment ended and fire sensitive hickories (Carya ovata and C. tomentosa), black cherry (Prunus serotina), sassafras (Sassafras albidum), and black oak (Quercus velutina) now dominate the seedling and sapling layers of the woodland.
Vascular plant checklists (floras) supply key information for biodiversity studies by providing a comprehensive picture of the floristic composition of a specific study area. A bibliography of floras conducted within the state of North Carolina was compiled. Eighty-six floras were completed within North Carolina between the years 1834 and 2009. Floras conducted in North Carolina cover areas of varying size, from small islands and state parks to entire counties. These studies include journal articles, government publications, technical reports and Master's theses. More than half of the flora citations were not published in scientific journals and were often difficult to discover or obtain.
The vascular plants of Sandy Run Savannas State Natural Area, located in portions of Onslow and Pender counties, North Carolina, are presented as an annotated species list. A total of 590 taxa in 315 genera and 119 families were collected from eight plant communities. Families with the highest numbers of species were the Asteraceae (80), Poaceae (66), and Cyperaceae (65). Two species, Carex lutea (golden sedge) and Thalictrum cooleyi (Cooley's meadowrue), have federal endangered status. A total of 23 taxa are tracked by the North Carolina Natural Heritage Program, while 29 others are considered rare, but not included on the priority list. Of 44 species considered strict endemic or near-endemic taxa to the North and South Carolina Coastal Plain, 18 (41%) were collected in this study. Selected pine savannas within the site were rated as nationally significant by the North Carolina Natural Heritage Program. Fifty-one (51) non-native species were present and represented 8.7% of the flora.
Amaranthus (Amaranthaceae) is a globally distributed plant genus composed of both weedy and cultivated species. While there have been previous attempts to resolve phylogenetic relationships within the genus, little attention has been placed on systematic relationships of the federally threatened coastal species Amaranthus pumilus Raf., endemic to eastern United States barrier islands, nor on genetic variability within the genus. In the present study, single primer ISSRs were employed to measure both genetic diversity and the phylogenetic position of A. pumilus. Leaf tissue samples were taken from wild populations on Fenwick Island, Delaware and from wild and propagated populations on Assateague Island National Seashore, Maryland. Genetic variation was detected among and within A. pumilus populations, though variability was low. Fenwick populations exhibited the highest genetic variability (h = 0.1016), while on Assateague the wild A. pumilus population had higher variability (0.0340) than the propagated population (0.0185). Due to its desirable characteristics in plant breeding trials, genetic variation within A. pumilus was also compared to variation of grain varieties A. hypochondriacus L. and A. cruentus L. Genetic diversity within A. pumilus was lower than either grain species sampled (0.2263 and 0.2947). Phylogenetic analyses included 41 accessions representing 33 Amaranthus species, and maximum parsimony, neighbor-joining, and Bayesian consensus trees were constructed. Though considerable phylogenetic signal was detected within the data matrix, phylogenetic resolution was low. Amaranthus pumilus grouped with the coastal species A. arenicola I.M. Johnst. in all consensus trees, which is the first postulated relationship of this pair.