| [on the nucleolytic effect of black birch tinder]. | | 1968 | 5190581 |
| canny's compensating pressure theory fails a test. | canny's compensating pressure theory for water transport (american journal of botany 85: 897-909) has evolved from the premise that cavitation pressures are only a few tenths of a megapascal negative (approximately -0.3 mpa). in contradiction, "vulnerability curves" indicate that xylem pressures can drop below -3 mpa in some species without causing a loss of hydraulic conductivity. canny claims these curves do not measure the limits to negative pressure by cavitation, but rather the limits to th ... | 1999 | 10449385 |
| hydraulic responses to environmental perturbations in tsuga canadensis and betula lenta. | eastern hemlock (tsuga canadensis (l). carr.) is a late-successional species found across the northeastern united states of america that is currently threatened by the exotic pest, hemlock woolly adelgid (adelges tsugae annand). because whole-tree physiological characteristics may scale to influence ecosystem processes, we considered whole-tree hydraulic controls in eastern hemlock and the replacement species black birch (betula lenta l.). through a series of misting perturbations, whole-tree re ... | 2008 | 18595846 |
| survivors, not invaders, control forest development following simulated hurricane. | wind disturbance profoundly shapes temperate forests but few studies have evaluated patterns and mechanisms of long-term forest dynamics following major windthrows. in 1990, we initiated a large hurricane simulation experiment in a 0.8-ha manipulation (pulldown) and 0.6-ha control area of a maturing quercus rubra--acer rubrum forest in new england. we toppled 276 trees in the pulldown, using a winch and cable, in the northwesterly direction of natural treefall from major hurricanes. eighty perce ... | 2013 | 23691660 |
| sawfly poisoning in sheep and goats. | in september 1984 some sheep in a flock of 250 suffered depression, anorexia, incoordination and difficulty in rising; 50 ewes and weaners died. post mortem examination revealed petechial bleeding, massive acute liver necrosis and in some animals degeneration of the kidney tubules. the rumen and gut contained many larvae of the blue-black birch sawfly (arge pullata). laboratory and field observations indicated that these were the cause of the illness. | 1987 | 2891213 |
| geographic variation and evolution in the life cycle of the witch-hazel leaf gall aphid, hormaphis hamamelidis. | two divergent life cycles associated with different elevations and latitudes have been documented for the witch-hazel leaf gall aphid, hormaphis hamamelidis. at low elevation in northern virginia, the aphid had seven distinct generations alternating between the primary host, witchhazel (hamamelis virginiana), and a secondary host, river birch (betula nigra). these findings confirm the original published life cycle description for the same locality. a second, abbreviated life cycle consisting of ... | 1989 | 28312355 |
| oak loss increases foliar nitrogen, δ(15)n and growth rates of betula lenta in a northern temperate deciduous forest. | oak forests dominate much of the eastern usa, but their future is uncertain due to a number of threats and widespread failure of oak regeneration. a sudden loss of oaks (quercus spp.) could be accompanied by major changes in forest nitrogen (n) cycles with important implications for plant nutrient uptake and tree species composition. in this study, we measured the changes in n use and growth rates of black birch trees (betula lenta l.) following oak girdling at the black rock forest in southeast ... | 2012 | 22851552 |
| sybr green- and taqman-based quantitative pcr approaches allow assessment of the abundance and relative distribution of frankia clusters in soils. | the nodule-forming actinobacterial genus frankia can generally be divided into 4 taxonomic clusters, with clusters 1, 2, and 3 representing nitrogen-fixing strains of different host infection groups and cluster 4 representing atypical, generally non-nitrogen-fixing strains. recently, quantitative pcr (qpcr)-based quantification methods have been developed for frankiae of clusters 1 and 3; however, similar approaches for clusters 2 and 4 were missing. we amended a database of partial 23s rrna gen ... | 2017 | 27986724 |
| foliar δ15n is affected by foliar nitrogen uptake, soil nitrogen, and mycorrhizae along a nitrogen deposition gradient. | foliar nitrogen isotope (δ(15)n) composition patterns have been linked to soil n, mycorrhizal fractionation, and within-plant fractionations. however, few studies have examined the potential importance of the direct foliar uptake of gaseous reactive n on foliar δ(15)n. using an experimental set-up in which the rate of mycorrhizal infection was reduced using a fungicide, we examined the influence of mycorrhizae on foliar δ(15)n in potted red maple (acer rubrum) seedlings along a regional n deposi ... | 2013 | 23070141 |
| interspecific variation in resistance of asian, european, and north american birches (betula spp.) to bronze birch borer (coleoptera: buprestidae). | bronze birch borer (agrilus anxius gory) is the key pest of birches (betula spp.) in north america, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. in a 20-yr common garden experiment initiated in 1979 in ohio, north american birch species, including paper birch (betula papyrifera marshall), 'whitespire' gray birch (betula populifolia marshall), and river birch (betula nigra l.), were muc ... | 2011 | 22251643 |
| simulating carbon dioxide exchange rates of deciduous tree species: evidence for a general pattern in biochemical changes and water stress response. | deciduous trees have a seasonal carbon dioxide exchange pattern that is attributed to changes in leaf biochemical properties. however, it is not known if the pattern in leaf biochemical properties - maximum rubisco carboxylation (v(cmax)) and electron transport (j(max)) - differ between species. this study explored whether a general pattern of changes in v(cmax), j(max), and a standardized soil moisture response accounted for carbon dioxide exchange of deciduous trees throughout the growing seas ... | 2009 | 19567419 |
| effects of winter temperatures on two birch (betula) species. | in massachusetts, low winter temperatures delay the onset of flowering in black birch (betula lenta l.), but not in gray birch (b. populifolia marsh.). during the winter of 2006, male inflorescences and twigs of black birch had higher water contents than those of gray birch, and the inflorescences of black birch experienced greater frost kill than those of gray birch. vessels diameters were greater in black than in gray birch, a difference associated with a higher incidence of winter xylem embol ... | 2008 | 18244951 |
| water use and carbon exchange of red oak- and eastern hemlock-dominated forests in the northeastern usa: implications for ecosystem-level effects of hemlock woolly adelgid. | water use and carbon exchange of a red oak-dominated (quercus rubra l.) forest and an eastern hemlock-dominated (tsuga canadensis l.) forest, each located within the harvard forest in north-central massachusetts, were measured for 2 years by the eddy flux method. water use by the red oak forest reached 4 mm day(-1), compared to a maximum of 2 mm day(-1) by the eastern hemlock forest. maximal carbon (c) uptake rate was also higher in the red oak forest than in the eastern hemlock forest (about 25 ... | 2008 | 18244947 |
| investigation of essential oil extracts from four native jamaican species of bursera for antibacterial activity. | bacterial infection with organisms resistant to antibiotics have increased during the last few decades worldwide. because of this increase, the authors decided to subject the essential oils from the stem, leaves and fruits of the four native jamaica species of bursera to microbial studies. | 2007 | 17621840 |
| metabolic response of river birch and european birch and european birch roots to hypoxia. | flood tolerance of woody plants has been attributed to internal oxygen diffusion from shoot to root, metabolic adaptation within the root, or both. the purpose of this study was to compare several biochemical and physiological responses of birch roots to hypoxia in order to determine the nature of root metabolic adaptation to low oxygen tension. one-year-old seedlings of flood-tolerant river birch (betula nigra l.) and flood-intolerant european birch (betula pendula roth) were transferred to sol ... | 1984 | 16663817 |
| forest regeneration composition and development in upland, mixed-oak forests. | advance regeneration in 52 mature mixed-oak stands was analyzed and described. red maple (acer rubrum l.) was the most abundant species in the study area. among oak (quercus) species, northern red oak (q. rubra l.) was the most abundant within the allegheny plateau physiographic province, whereas chestnut oak (q. montana l.) was the most abundant within the ridge and valley physiographic province. sixteen stands, for which data are available through the fourth growing season following harvest, w ... | 2005 | 16137935 |
| abundance and relative distribution of frankia host infection groups under actinorhizal alnus glutinosa and non-actinorhizal betula nigra trees. | quantitative polymerase chain reaction (qpcr) was used to assess the abundance and relative distribution of host infection groups of the root-nodule forming, nitrogen-fixing actinomycete frankia in four soils with similar physicochemical characteristics, two of which were vegetated with a host plant, alnus glutinosa, and two with a non-host plant, betula nigra. analyses of dapi-stained cells at three locations, i.e., at a distance of less than 1 m (near stem), 2.5 m (middle crown), and 3-5 m (cr ... | 2016 | 26143359 |
| heterodera betulae n. sp. (heteroderidae), a cyst-forming nematode from river birch. | a new species of the genus heterodera a. schmidt, 1871 parasitic on river birch, betula nigra l., is described and illustrated. females and cysts are lemon-shaped to almost spherical with slight vulval protrusion. female cuticles have a thick subcrystalline layer. the average cyst size is 763 by 616 [mu]. they are circumfenestrate with small anal opening and lack a yellow phase. the cyst wall pattern is typically network-like. all eggs are retained in the cyst, although a well-developed matrix i ... | 1969 | 19325672 |
| changes in composition, structure and aboveground biomass over seventy-six years (1930-2006) in the black rock forest, hudson highlands, southeastern new york state. | we sought to quantify changes in tree species composition, forest structure and aboveground forest biomass (agb) over 76 years (1930-2006) in the deciduous black rock forest in southeastern new york, usa. we used data from periodic forest inventories, published floras and a set of eight long-term plots, along with species-specific allometric equations to estimate agb and carbon content. between the early 1930s and 2000, three species were extirpated from the forest (american elm (ulmus americana ... | 2008 | 18244941 |