Mountain Laurel Research Articles

Remembering

Remembering Renea Winchester (bio) This year marks the seventy-fifth anniversary of the Great Smoky Mountains National Park. May all who have family buried there return to their heritage and remember, and may others seeking to learn more about the families who lost their homes experience the majesty and wonder of the land many called home. The road narrows and turns to grass. I inhale deeply and fight back tears. I am home. Several generations of family members have loaded into the back of pickup trucks then parted a sea of tourists to visit a place we hold sacred. While others flock to the Great Smoky Mountains National Park to play, we travel to a place few will ever see. We travel in part out of duty and respect. We travel to honor our heritage, and remember. Before we reach this sacred ground, Dad must maneuver through visitors who believe they are alone in the wilderness. Children trample endangered species of flora and fauna. Tree limbs are broken for walking sticks. They maneuver cumbersome remnants from worn out tires and expel water through soggy shoes with a squish. They walk, through no fault of their own, unaware of the history these grand mountains possess. Not too long ago, the creek was the lifeblood of the community. White water rapids transported enormous hand-cut logs to town where Carolina Wood Turning Company converted them into lumber. The crystal clear water also held tiny nuggets of gold few ever found. The creek provided families with fish and offered a cool drink. But today, in our hurried world, we don't seem to need the creek for food or water. Her purpose now is recreation. My feet dangle from the edge of the tailgate. "Hi ya'll," I wave then quickly add, "how ya'll doin'?" My overdrawn greeting evokes an eye roll. "How did these trucks get in here?" Someone says as we pass. The caravan of trucks presses higher and soon reaches the place where tubing is prohibited. Dad takes the left fork, and I give a final wave as we leave civilization. The sound of water tickling rocks can be heard above the rumbling of rusty tailpipes. I close my eyes, inhale deeply, and lift my face toward the heavens. [End Page 65] Beside me, my aunt says, "No place in the world smells as good as this." The fragrance, a mixture of vanishing memories, honeysuckle, and decaying leaves, tugs at my heart, squeezing out painful remembrances with each beat. As a child, I piled in the back of an older, rustier pickup truck. In those days you could ride on the main highway in the back of a truck without getting a ticket. My heart longs for those times again; when I sang songs to the top of my lungs and stood on my tiptoes to pick leaves from low-hanging limbs. Today, I duck as we pass under the same trees and keep a watchful eye on children as they reach toward the heavens to capture leaves. This year the weather is beautiful, and bugs are few. Mountain laurel welcomes us with a grand display. White umbrella-like blooms litter the road. I smile and watch a breeze pluck a peppermint-colored bloom and spin it to the forest floor where it lands without a sound. Dad interrupts my sightseeing when he yells out the window, "Pick up your feet. There's a hog-waller up ahead." I scan the woods, hoping to see the hog that has been rolling around in the dingy mud puddle. For a moment, I feel five years old. I'm anxious to touch this place. I want to leap from the truck and splash about in the mud. Instead, I pick up my feet as the truck disturbs the puddle so my shoes won't be sucked off. My laughter mixes with the children's and echoes through the valley as the truck bounces from side to side. "Hang on back thair," Dad calls. The muddy water crashes back in place. Not a single shoe is lost. It's a good day. Overhead the hemlocks are loosing the battle with the Wooly...

Terrain and Landform Influence on Tsuga canadensis (L.) Carrière (Eastern Hemlock) Distribution in the Southern Appalachian Mountains

We examined the relationships between hemlock distribution and abundance and terrain attributes for the Coweeta Basin in the southern Appalachian Mountains. Field measurements were combined with GIS mapping methods to develop predictive models of abundance and distribution of Tsuga canadensis (L.) Carrière (eastern hemlock) and evaluate the co-occurrence of Rhododendron maximum L. (rosebay) and Kalmia latifolia L. (mountain laurel). Terrain variables were derived from USGS DEM 30-meter digital maps. Elevation, slope, aspect, terrain shape index, landform, and distance from stream were calculated from field measurements and the digital data. Terrain attributes such as elevation (r2 = 0.97, p < 0.0001), distance to stream (r2 = 0.94, p < 0.0001), and terrain shape index (r2 = 0.61, p = 0.0015) were good predictors of T. canadensis abundance. Terrain shape index explained 56% of the variation in R. maximum percent aerial cover (r2 = 0.56, p = 0.005). In the Coweeta Basin, T. canadensis was distributed as few, large trees mostly concentrated in near-stream locations, and it was closely associated with R. maximum. Tsuga canadensis mortality due to Adelges tsugae Annand (hemlock wooly adelgid) will result in a minor decrease in basin-wide basal area, but will substantially reduce near-stream basal area, and will also remove the largest trees in near-stream environments. In similar landscapes across the southern Appalachians, where T. canadensis co-occurs with R. maximum, riparian shading will likely remain unchanged.

Salinity Tolerance of Sophora secundiflora and Cercis canadensis var. mexicana

Use of reclaimed water to irrigate urban landscapes will likely increase because fresh water supply is diminishing and the population continues to grow in the semiarid southwestern United States. Salt tolerance of two native landscape woody ornamentals, Texas mountain laurel (Sophora secundiflora) and Mexican redbud (Cercis canadensis var. mexicana), was investigated in a greenhouse experiment. Seedlings of the two species were grown in two substrates mixed with composted mulch and a commercial potting mix at two ratios and irrigated with saline solutions at three salinity levels: 1.6 (control, nutrient solution), 3.0, or 6.0 dS·m−1 electrical conductivity (EC). There was no interaction between substrate and EC of irrigation water. Foliar salt damages such as leaf drop, leaf curl, and edge burn were observed in Mexican redbud when the plants were irrigated with solutions at EC of 3.0 and 6.0 dS·m−1. No symptoms were observed on Texas mountain laurel plants, although plants irrigated at EC of 3.0 and 6.0 dS·m−1 were smaller compared with controls. Shoot growth and elongation of both species were reduced by the elevated salinity of irrigation water, and the reduction in Mexican redbud was greater than Texas mountain laurel. Leaf photosynthesis rate and leaf stomatal conductance were also reduced in Texas mountain laurel by the elevated salinity of irrigation water. Tissue Na+ and Cl– concentrations were higher in Texas mountain laurel irrigated with water of elevated salinity.

Spatial pattern in herb diversity and abundance of second growth mixed deciduous-evergreen forest of southern New England, USA

This study was designed to answer questions about the patterns of understory diversity in managed forests of southern New England, and the factors that appear associated with those patterns. At the landscape-level, we used plot data to answer questions regarding the spatial distribution of forest understory plant species. Data from a combination of fixed area (understory vegetation) and variable radius (overstory trees) plot methods are combined with site variables for the analysis. Univariate and multivariate statistical methods are used to test for understory diversity relationships with overstory cover types and topography separately, and in combination. Analyses also test for relationships between specific understory species and cover types. In general the understory flora is dominated by four common clonal species that occur across the range of forest cover types: wild sarsaparilla ( Aralia nudicaulis L.), Canada mayflower ( Maianthemum candense Desf.), star flower ( Trientalis borealis Raf.), and partridgeberry ( Mitchella repens L.). Results also show that over story composition and structure can be used to assess understory species richness. Species richness follows a general trend among cover types of: hardwood ≥ regenerating forest, hardwood–pine, and pine ≥ mixed ≥ hardwood–hemlock > hemlock. Eastern hemlock ( Tsuga canadensis L. Carriere) and mountain laurel ( Kalmia latifolia L.) (which decreased in dominance from ridge to valley) both showed negative trends with understory species richness. Topographic position also appears associated with understory floristic patterns (particularly for the hardwood cover type), both in terms of species richness and compositional diversity which both increased from ridge, to midslope, to valley. However, overstory composition (covertype) appears to have a higher order influence on vegetation and mediates the role of topography. The results from this study provide foresters with a better understanding for maintaining floristic diversity and composition of the understory in managed forests.

Applying Hotspot Detection Methods in Forestry: A Case Study of Chestnut Oak Regeneration

Hotspot detection has been widely adopted in health sciences for disease surveillance, but rarely in natural resource disciplines. In this paper, two spatial scan statistics (SaTScan and ClusterSeer) and a nonspatial classification and regression trees method were evaluated as techniques for identifying chestnut oak (Quercus Montana) regeneration hotspots among 50 mixed-oak stands in the central Appalachian region of the eastern United States. Hotspots defined by the three methods had a moderate level of conformity and revealed similar chestnut oak regeneration site affinity. Chestnut oak regeneration hotspots were positively associated with the abundance of chestnut oak trees in the overstory and a moderate cover of heather species (VacciniumandGaylussaciaspp.) but were negatively associated with the abundance of hayscented fern (Dennstaedtia punctilobula) and mountain laurel (Kalmia latiforia). In general, hotspot detection is a viable tool for assisting natural resource managers with identifying areas possessing significantly high or low tree regeneration.

Variation in Soil and Forest Floor Characteristics Along Gradients of Ericaceous, Evergreen Shrub Cover in the Southern Appalachians

Ericaceous shrubs can influence soil properties in many ecosystems. In this study, we examined how soil and forest floor properties vary among sites with different ericaceous evergreen shrub basal area in the southern Appalachian mountains. We randomly located plots along transects that included open understories and understories with varying amounts of Rhododendron maximum (rosebay rhododendron) and Kalmia latifolia (mountain laurel) at three sites. The three sites were a mid-elevation ridge, a low-elevation cove, and a high-elevation southwest-facing slope. Basal area of R. maximum was more correlated with soil properties of the forest floor than was K. latifolia. Increasing R. maximum basal area was correlated with increasing mass of lower quality litter and humus as indicated by higher C:N ratios. Moreover, this correlation supports our prediction that understory evergreen shrubs may have considerable effect on forest floor resource heterogeneity in mature stands.

In a Dream of the Locust

Silence green and filling with wind. Into the core where the eye was born in darkness Blessed in a fugue of pulsations Ivory beginnings returned The mountain laurel reached its peak in the acidic shale We cannot help noticing what makes us disappear We cannot help believing in the silence that made us Out of the great death that emptied us Squirming in a bucket of song and laughter. Where did such a sound find a beginning Where did such a beginning find a sound To claim and name itself. A pulsation that cannot help itself Even as we are carried in our machines To the ends of our tissue, the ends of o r matter. Soon we will not fear the end of things Soon the locust will reverse itself in our sleep.

Long-Term Effects of High Intensity Prescribed Fire on Vegetation Dynamics in the Wine Spring Creek Watershed, Western North Carolina, USA

We examined the long-term effects of a prescribed fire in a southern Appalachian watershed in Nantahala National Forest, western North Carolina, USA. Fire was prescribed in 1995 on this site by forest managers to restore a degraded pine (Pinus spp.)-hardwood community, specifically to stimulate forage production, promote pine and oak (Quercus spp.) regeneration, and increase plant diversity. Before and after the prescribed fire, permanent plots were sampled across a south-facing hillslope, which corresponded to three community types: mesic, near-stream cove (riparian); dry, mixed-oak (mid-slope); and xeric, pine-hardwood (ridge). In an earlier paper, we reported the first two years of post-burn vegetation response from this prescribed burn. In our current study, we compared the pre-burn (1994) forest condition with 10 years post-burn (2005) vegetation measurements to determine the effects of fire on the mortality and regeneration of overstory trees, understory shrubs, and herbaceous-layer species. Overstory mortality was high immediately after the burn at the ridge location and ten years after the fire. Mortality of pitch pine (Pinus rigida Miller) (91.8 %) and hickory (Carya spp.) (77.5 %) reduced overstory basal area from 26.97 m2 ha−1 pre-burn to 18.86 m2 ha−1 post-burn in 1995 and to 9.13 m2 ha−1 in 2005. At the mid-slope and riparian locations, no significant overstory mortality occurred over time. Understory density was significantly higher 10 years after the burn (2005) than pre-burn, and basal area had returned to pre-burn levels. Density of mountain laurel (Kalmia latifolia L.), black huckleberry (Gaylussacia baccata [Wang.] K. Koch), and blueberry (Vaccinium spp.) had increased due to prolific sprouting. The prescribed fire had varying effects on diversity across the hillslope gradient over time. On the ridge, overstory diversity declined following the fire (H’basal area = 1.14 in 1994, H’basal area = 0.75 in 1995, and H’basal area = 0.80 in 2005). Diversity significantly increased in the herbaceous layer and remained higher than pre-burn conditions through 2005 (H’cover = 1.02 in 1994, H’cover = 1.97 in 1995, and H’cover = 2.25 in 2005). For the mid-slope and riparian positions, no change in diversity was observed in the overstory, understory or herbaceous layer.

Suitability of Different Host Plants for Oviposition and Development of Homalodisca vitripennis (Hemiptera: Cicadellidae) and Its Implication on Mass Rearing

Abstract The glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), is a major pest of grapevine (Vitis vinifera L.) in Texas and California. It is a known vector of Pierce's disease and is considered the most significant insect pest threatening the grape industry in the United States. We evaluated the preference of four host plants for feeding and oviposition by H. vitripennis adult females. We also measured the suitability of nine host plants for the growth and development of eggs and nymphs under greenhouse and laboratory conditions, respectively. Embryonic survival exceeded 85% on all tested host plants, with the exception of sweet potato, Ipomoea batatas (L.) Lam. More than 80% of the nymphs successfully reached adulthood on sweet potato, black-eyed pea [Vigna unguiculata unguiculata (L.) Walp.], and eggplant (Solanum melongena L). Developmental time of immature H. vitripennis nymphs was significantly affected by the plants on which they fed. The nymphs were more likely to die during the first instar on host plants such as Texas mountain laurel Evonymus japonica (Thunb.), or citrange Citrus sinensis × Poncirus trifoliata. Host suitability (nutrients) and stem and leaf texture, which varied among host plant species selected, seem to both play a significant role in nymphal development. Adult females were able to feed on woody plants, but a preference for black-eyed pea and sweet potato was observed. In captivity and given the plant choices offered, they deposited more egg masses on hibiscus (Hibiscus rosa-sinensis L.) and black-eyed pea.

Organic Matter Application Improves Posttransplant Root Growth of Three Native Woody Shrubs

The need for reliable planting techniques that encourage posttransplant root growth in adverse conditions has prompted research into planting above soil grade (above-grade). Container-grown Morella cerifera (L.) Small (syn. Myrica cerifera L.) (wax myrtle), Illicium floridanum Ellis (Florida anise tree), and Kalmia latifolia L. (mountain laurel) plants were planted in Horhizotrons (root observation chambers) in a greenhouse in Auburn, AL, on 1 Mar. 2006, 6 June 2006, and 3 Jan. 2007, respectively. The experiment was repeated with all three species being planted 18 June 2007. Horhizotrons contained four glass quadrants extending away from the root ball providing a nondestructive method for measuring root growth of the same plant into different rhizosphere conditions. Each quadrant was filled with a native sandy loam soil in the lower 10 cm. The upper 10 cm of the quadrants were filled randomly with: 1) milled pine bark (PB); 2) peat (P); 3) cotton gin compost (CGC); or 4) more native soil with no organic matter (NOM). Horizontal root lengths (HRL, length measured parallel to the ground from the root ball to the root tip) of the five longest roots visible along each side of a quadrant were measured weekly for M. cerifera and I. floridanum and biweekly for K. latifolia. These measurements represented lateral growth and penetration of roots into surrounding substrates on transplanting. When roots of a species neared the end of the quadrant, the experiment was ended for that species. M. cerifera had the fastest rate of lateral root growth followed by I. floridanum and then by K. latifolia. In most cases, roots grew initially into the organic matter rather than the soil when organic matter was present. In general, HRL and root dry weight (RDW) of I. floridanum and K. latifolia were greatest in PB and P, whereas for M. cerifera, these were greatest in P. Differences in root growth among substrates were not as pronounced for M. cerifera as for the other species, perhaps as a result of its rapid increase in HRL. Increased root growth in PB and P may be attributed to the ideal physical and chemical properties of these substrates. Results suggest that planting above soil grade with organic matter may increase posttransplant root growth compared with planting at grade with no organic matter.

Effect of Backfill Composition on Post-Transplant Root Growth of Kalmia latifolia L.

Abstract Post-transplant root growth is critical for landscape plant establishment. The Horhizotron™ provides a way to easily measure root growth in a wide range of rhizosphere conditions. Mountain laurel (Kalmia latifolia L.) plants were removed from their containers and planted in Horhizotrons in a greenhouse in Auburn, AL, and outdoors in Blacksburg, VA. Each Horhizotron contained four glass quadrants extending away from the root ball, and each quadrant within a Horhizotron was filled with a different substrate (treatment): 1) 100% pine bark (Pinus taeda L., PB), 2) 100% soil, 3) a mixture of 50:50 (by vol) PB:soil, or 4) 100% soil along the bottom of the quadrant to a depth of 10 cm (4 in) and 100% PB layered 10 cm (4 in) deep on top of the soil. Root growth along the glass panes of each quadrant was measured bi-weekly in Auburn and weekly in Blacksburg. In both locations, roots were longer in all treatments containing pine bark than in 100% soil. When pine bark was layered on top of soil, roots grew into the pine bark but did not grow into the soil. Results suggest that amending soil backfill with pine bark can increase post-transplant root growth of container-grown mountain laurel.

Effect of Root-zone Temperature on Survival, Growth, and Root Morphology of Kalmia latifolia and Ilex crenata ‘Compacta’

Abstract Root-zone temperature (RZT) is an important environmental factor affecting growth and performance of woody ornamental plants in the landscape. Research was conducted to compare the effects of RZT on survival, growth, and root morphology of a difficult-to-transplant species, mountain laurel (Kalmia latifolia L.), and an easy to transplant species, Japanese holly (Ilex crenata Thunb.). Seedlings of mountain laurel or micropropagated liners of mountain laurel (Kalmia latifolia L. ‘Sarah’) and rooted stem cuttings of Japanese holly (Ilex crenata Thunb. ‘Compacta’) were grown hydroponically for 12 weeks in controlled environment conditions under long days at 9-hr days/15-hr nights of 26/22C (79/72F) with RZTs of 16, 24, or 32C (61, 75, or 90F). Compared to 16 and 24C (61 and 75F), percent survival of mountain laurel was reduced by a RZT of 32C (90F), whereas percent survival of Compacta holly was unaffected by RZT. Root dry weight of mountain laurel was reduced 72% at 32C (90F) while top dry weight was unaffected by RZT. Top and root dry weights of Compacta holly were unaffected by RZT. Root: top ratio of mountain laurel was reduced by increasing RZT, whereas root: top ratio of Compacta holly was unaffected by RZT. Root area of mountain laurel and Compacta holly were reduced 80 and 64%, respectively, at 32C (90F) compared with 16C (61F). Number of lateral roots in the apical 2 cm (0.8 in) of primary roots of both taxa increased with increasing RZT. Results of this research indicate that reducing RZT in the landscape may increase survival and root growth of transplanted mountain laurel.

Fuels on disturbed and undisturbed sites in the southern Appalachian Mountains, USA

Fuel distribution in the southern Appalachian Mountain region was measured in over 1000 study plots that were stratified by topographic position (aspect and slope position) and disturbance history. Few fuel differences occurred among topographic positions for undisturbed plots, indicating that fuel accumulation is no greater on highly productive sites than on less productive sites. Litter was slightly higher on undisturbed upper slopes (4.2 t/ha) than on lower slopes (3.7 t/ha) but woody fuels showed no significant differences. Rhododendron ( Rhododendron spp.) and mountain laurel ( Kalmia latifolia L.) were less common than expected, occurring on 25% and 42% of sampled plots, respectively. Disturbance history and type played a greater role in determining fuel loads than did topographic position. Disturbances had occurred on 30% of sample plots within the past 10 years and were most common on exposed slopes. Litter was significantly lower in burned plots (3.5 t/ha vs. 4.0 t/ha in undisturbed plots). One-hour fuels (1.0 t/ha) were significantly higher on beetle-killed plots than on undisturbed plots (0.7 t/ha) while larger woody fuels tended to be greater in plots subjected to beetle attack, fire, and wind.

Phylogeography of a ground beetle species in La Gomera (Canary Islands): the effects of landscape topology and population history

Paraeutrichopus pecoudi (Coleoptera, Carabidae) is a species endemic to the mountain laurel forests of La Gomera in the Canary archipelago. La Gomera is an island of volcanic origin (9.4 mya), where a well-preserved laurel forest is partly fragmented by valleys and ridges. Historically restricted gene flow with isolation by distance are deduced at different clade levels for P. pecoudi populations, an expected scenario arising from landscape discontinuity, which has caused local isolation of these flightless insects. Methodological considerations were investigated for nested clade phylogeographic analysis (NCPA), comparing the results obtained using either (a) pairwise distances between collecting sites measured as surface (route) distances or (b) standard geographical distances calculated from latitude-longitude coordinates. Some differences were found in the NCPA statistics and associated inferences at the higher clade levels in relation to the assumed distance criteria. Coalescent simulations and posterior automated NCPAs assuming different geographical distances were performed to test the robustness of the method when considering the distances used. These analyses showed no significant differences in NCPA conclusions, and the scenario of restricted gene flow was recovered using both distance calculators at the same rate, although the parameter statistics were slightly different. We suggest that in landscapes with extreme topography, geographical distances separating populations are certainly underestimated by standard techniques. More complex and explicit descriptions of the potential dispersal of terrestrial organisms should be explored for implementation in statistical phylogeography in such cases.

Use of Landsat ETM and Topographic Data to Characterize Evergreen Understory Communities in Appalachian Deciduous Forests

Evergreen understory vegetation was classified using Landsat ETM imagery and ancillary data in two physiographic provinces in the central Appalachian highlands; the Ridge and Valley and the Allegheny Plateau. These evergreen understory communities are dominated by rosebay rhododendron (Rhododendron maximum L.) and mountain laurel (Kalmia latifolia L.), which are spatially extensive and ecologically important to the structure and functioning of Appalachian forests. DEM-derived topographic information was integrated with Landsat data to assess its potential to improve classification accuracy, maximum likelihood, and minimum distance, and decision tree classification approaches were tested with these data in a factorial manner. An overall accuracy of 87.1 percent (K hat =.806) was achieved in the Ridge and Valley province by employing a maximum likelihood approach using Landsat data alone, while an 82.9 percent overall accuracy (K hat =.755) was obtained for the Allegheny Plateau employing a hybrid decision tree classification approach with Landsat and topographic data.

BBGD: an online database for blueberry genomic data

BackgroundBlueberry is a member of the Ericaceae family, which also includes closely related cranberry and more distantly related rhododendron, azalea, and mountain laurel. Blueberry is a major berry crop in the United States, and one that has great nutritional and economical value. Extreme low temperatures, however, reduce crop yield and cause major losses to US farmers. A better understanding of the genes and biochemical pathways that are up- or down-regulated during cold acclimation is needed to produce blueberry cultivars with enhanced cold hardiness. To that end, the blueberry genomics database (BBDG) was developed. Along with the analysis tools and web-based query interfaces, the database serves both the broader Ericaceae research community and the blueberry research community specifically by making available ESTs and gene expression data in searchable formats and in elucidating the underlying mechanisms of cold acclimation and freeze tolerance in blueberry.DescriptionBBGD is the world's first database for blueberry genomics. BBGD is both a sequence and gene expression database. It stores both EST and microarray data and allows scientists to correlate expression profiles with gene function. BBGD is a public online database. Presently, the main focus of the database is the identification of genes in blueberry that are significantly induced or suppressed after low temperature exposure.ConclusionBy using the database, researchers have developed EST-based markers for mapping and have identified a number of "candidate" cold tolerance genes that are highly expressed in blueberry flower buds after exposure to low temperatures.

(64) Effect of Backfill Composition on Posttransplant Root Growth of Kalmia latifolia L.

Posttransplant root growth is critical for landscape plant establishment. The Horhizotron provides a way to easily measure root growth in a wide range of rhizosphere conditions. Mountain laurel (Kalmia latifolia L.) plants were removed from their containers and planted in Horhizotrons in a greenhouse in Auburn, Ala., and outdoors in Blacksburg, Va. Each Horhizotron contained four glass quadrants extending away from the root ball, and each quadrant within a Horhizotron was filled with a different substrate (treatment): 1) 100% pine bark (Pinus taeda L., PB), 2) 100% soil, 3) a mixture of 50 PB: 50 soil (by volume), or 4) 100% soil along the bottom of the quadrant to a depth of 10 cm (4 inches) and 100% PB layered 10 cm (4 inches) deep on top of the soil. Root growth along the glass panes of each quadrant was measured biweekly in Auburn and weekly in Blacksburg. Roots were longer in all treatments containing pine bark than in 100% soil. When pine bark was layered on top of soil, roots grew into the pine bark but did not grow into the soil. Results suggest that amending soil backfill with pine bark can increase posttransplant root growth of container-grown mountain laurel.

Carbon sequestration and nutrient cycling implications of the evergreen understory layer in Appalachian forests

Evergreen understory communities dominated by mountain laurel ( Kalmia latifolia L.) and/or rosebay rhododendron ( Rhododendron maximum L.) are an important but often overlooked component of Appalachian forests. In the dense thickets in which these species often occur, they have high carbon sequestration potential and play important roles in nutrient storage and cycling. We used allometric modeling of the aboveground biomass to quantify the importance of K. latifolia and R. maximum, relative to overstory tree species, in driving biogeochemical cycling in the Central Appalachian mountains. Carbon sequestration and nitrogen and phosphorus storage potentials were investigated by running 50-year simulations of the ecosystem accounting model NuCSS for two situations: forests comprising the canopy overstory layer with or without the evergreen understory layer. When simulating forests in several test watersheds based only on the composition and biomass of the overstory canopy, these forests contain between 1631 and 4825 kg/ha less in overall C content and 41–224 kg/ha less N content than if the evergreen understory layer is included. Additional N uptake by evergreen understory vegetation was estimated to amount to between 6 and 11 kg N ha −1 yr −1 at year 50 for the overstory-with-understory forest compared to the overstory-only forest. Vegetation pool nutrient storage was higher by 2–4% for N, and by 2–14% for P at year 50 when R. maximum and K. latifolia were included in the model. Aboveground standing biomass of R. maximum and K. latifolia accounted for only a modest portion of the C sequestered and N stored in the forest ecosystems at the watershed scale. In contrast, notably higher amounts of C and N were simulated as stored in the forest floor and soil pools when the understory was included. N storage predominated in the forest floor compared to the soil pool when a larger amount of R. maximum was present in a watershed, most likely due to the larger amounts of recalcitrant litter produced annually by this species compared to K. latifolia. In addition, storage of P in K. latifolia and R. maximum exceeded expectations compared to their watershed-scale standing biomass.

Embryo germination and proliferation in vitro of Juglans regia L.

This paper presents the optimal culture conditions for the in vitro embryo germination and proliferation of Juglans regia L. rootstock cv. Peralta, selected by the IMIDA fruticulture team. J. regia L. rootstock cv. Peralta is characterised by its resistance to salinity, lime and by its vigour. The first experiment determined the best culture medium for in vitro embryo germination. The Murashige and Skoog medium (MS; Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassays with tobacco tissues cultures. Physiol. Plant. 15, 473–497), the medium developed by our team for walnut (NGE), the Lloyd and McCown medium (WPM; Lloyd, G., McCown, B., 1981. Commercially feasible micropropagation of mountain laurel, Kalmia latifolia, by the use of shoot tip culture. Proc. Plant Prop. Soc. 30, 421–427) and that of Driver and Kuniyuki (DKW; Driver, J.A., Kuniyuki, A.M., 1984. In vitro propagation of Paradox walnut rootstock. HortScience 19 (4), 507–509), were compared, all without growth regulators. The best germination percentage was obtained in WPM (81%) with significant differences between the different media. In the second experiment, the optimal benzylaminopurine and indole butyric acid concentrations were determined for the proliferation stage of the explants obtained in the first experiment. The proliferation rates obtained varied from 0 in the medium without cytokinins to 6 in the medium with 0.5 mg l −1 BAP. The cluster proliferation quality and other parameters studied indicate that the optimal treatment was 0.5 mg l −1 BAP.

From Genealogy, a novel

from Genealogy, a novel Maud Casey (bio) Firefly Flash It becomes one of those family stories, the kind the family is so good at telling, a story more real than the event itself. See, look, this explains everything. That night, the family still trembles with an adrenaline rush that comes from dodging death, death who has stepped out of the shadows where it's been lurking all along, foolishly forgotten. In honor of the event, Sam institutes mandatory family dinner. She announces this in what Bernard calls her inimitable Midwestern way (he calls it this because it annoys her but also because it makes her feel known) – Let's fix an existential crisis, but quick, with something practical, he drawls until she throws something substantial but not dangerous, a spoon, a breadbasket, tonight a flip-flop. "No more drifting in and out. No more eating in front of the television. No more blah, blah, blah, fuzzy around the edges," Sam says from where she leans into a stuck window with her shoulder. The sleeves of the loose blouse she put back on after the accident flutter in the breeze coming in the window on the other side of the room, the one she has succeeded in opening. Through the window, stony Rhode Island fields and fields and more fields filled with mountain laurel, Hollow Joe Pye Weed, jeweled forget-me-nots, eggs-and-butter, Queen Anne's lace, mullein, goldenrod. The gray bark on the trees, trunks entwined with the vines of wild grapes, turns rose with the setting sun, and in the distance, the ocean is a quivering blue line. This new place is paradise; before they went to the beach this afternoon, Sam took the children to pick blackberries from the bushes just outside the front door, and the children stained their hands purple despite her best efforts to keep them from eating all of the berries so there would be enough for a pie. There's not, but she doesn't care. They can do whatever they want. The life preserver snagged on the rocks, held their daughter aloft. They are a lucky, lucky family. She is a lucky, lucky [End Page 28] woman, and she will do whatever it takes to prove she never wanted to be anything else, that there never was a moment, a flash, a blink, a not-even-a-second, when she didn't want her children to be alive and well, when a tragedy might have suited her. "Why does it have to sound like a punishment?" Bernard teases. He's in a great mood. "Mandatory family dinner." He leans over what used to be the train depot's ticket counter, now serving as the entrance to the kitchen, hands in the lobster-claw pot holders Marguerite loves, and twirls a fork around his ear: cuckoo, cuckoo. "Where is your italicist?" Sam asks, grunting as she still tries to open the window. "You know that little man who jumps up and down behind you whenever you make a really important point?" This is a new family joke, one Sam is especially proud of because the first time she made it, Bernard spit the water he was drinking onto his plate. "By the way," Sam says, laughing despite herself at her own joke, "if I ever get this window open, I'm throwing myself out of it." Bernard sticks his head out over the ticket counter again, this time with a spice bottle in each lobster-claw hand. "Don't throw yourself out of the window yet. Wait until we've had dinner." And suddenly the window flies open and there is the smell of the blooming flowers of late spring, and the warm, salty breeze off the ocean, and the underlying rich odor of cow manure. The original giant clock from the train depot hangs in between the bay windows over Sam's head; its second hand sweeping through time as if dismissing it: out of my way! "We'll eat together like those families we've only heard about and we'll enjoy it!" Sam shouts. She collapses in an armchair stuffed with dolls bought at a thrift store, a...