Journal of the Torrey Botanical Society最新文献

{"title":"Effects of individual bunchgrasses on potential C and N mineralization of longleaf pine savanna soils1","authors":"J. West, L. Donovan, J. Torrey","doi":"10.2307/4126913","DOIUrl":"https://doi.org/10.2307/4126913","url":null,"abstract":"WEST, J. B. AND L. A. DONOVAN. (Department of Plant Biology, University of Georgia, Athens, GA 30602). Effects of individual bunchgrasses on potential C and N mineralization of longleaf pine savanna soils.3 J. Torrey Bot. Soc. 131:120-125. 2004.-A recent conceptual model of grasslands in the US argues that, because of the discontinuous cover of plants in systems strongly limited by precipitation, the presence or absence of individual plants has significant effects on soil processes, with relatively small effects of species differences. In systems not strongly limited by precipitation, resource limitations are thought to vary in space and time, vegetation is more continuous, and species differences are relatively more important. We ask whether the model can be applied to grass species effects on potential net C and N mineralization in a southeastern US savanna ecosystem. These savannas have very sandy soils, strong soil resource limitations, and discontinuous plant cover, even though they receive 1200 mm yr-' rainfall. Based on the discontinuous herbaceous vegetation, an extension of the model would predict that native perennial bunchgrasses would have strong plant presence effects, and small or no species identity effects on these soil processes. Soils were sampled in a paired fashion, directly under a plant (either Aristida stricta, Schizachyrium scoparium, or Andropogon ternarius) and in adjacent unvegetated locations, and aboveground biomass was collected. Net C-min was significantly higher under plants compared to unvegetated locations, but there were also significant species identity effects, with the greatest rates observed under A. stricta. This pattern is likely explained by the greater biomass of A. stricta, because net C-min was positively related to biomass. For net N-min, there were neither plant presence nor species identity effects. There was, however, a positive relationship between net C-min and net N-min for both S. scoparium and A. ternarius soils, but not for A. stricta, suggesting a subtle, but potentially important, difference among species in their effects on N cycling. The results suggest that individual grasses have significant effects on soil processes in this system, but that the conceptual model developed for grasslands may not generalize to the effects of grasses on the soils of these savannas.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126913","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controls on the distribution of Mnium arizonicum along an elevation gradient in the Front Ranges of the Rocky Mountains, Alberta1","authors":"N. Cleavitt","doi":"10.2307/4126916","DOIUrl":"https://doi.org/10.2307/4126916","url":null,"abstract":"endemic to North America and in the northern Rocky Mountains it occurs most abundantly in the understory of subalpine tree islands formed by Abies lasiocarpa and Picea engelmannii. This species reproduces almost entirely through apical fragment regeneration and its expansion into lower elevation sites may be dispersal limited. Mnium arizonicum was experimentally dispersed along an elevation gradient as apical fragments and colony transplants. Individual performance was expected to interact with factors that vary with elevation such as habitat characteristics and competition intensity. Habitat characteristics were assessed at the site level by detailed site mapping and at the scale of the study area by restricted-random 5 m radius plots. The interaction between M. arizonicum and Hylocomium splendens was investigated for a switch from competition to facilitation along the elevation gradient. The experimental design included six elevation classes with three replicate sites and within each site two microsites (Picea tree base and Hylocomium carpet) each with three replicate plots. At sites where M. arizonicum was most abundant, it was excluded from the smallest tree islands with higher tree densities. In the region of the study area, the occurrence of M. arizonicum was most probable around tree bases located at 2000+ m with a thin (< 3 cm) litter layer and with one or more other bryophyte species present at the same tree base. The effects of microsite (Picea base versus Hylocomium carpet) on M. arizonicum performance were clearer in both life stages than the effects of elevation. Hylocomium microsites had consistently lower regeneration of apical fragments, but higher in situ effective quantum yield of adult transplants compared with Picea bases. Within the Picea base microsites, plots at intermediate elevations (1600-1800 m) received more light and were sub-optimal in terms of fragment regeneration, fragment sprout production, and in situ effective quantum yield of adult transplants. In the study area, the ability of M. arizonicum to extend its range into lower elevation sites was limited at intermediate elevations around tree bases that had deeper litter layers at intermediate elevation sites and in Hylocomium microsites by competitive pressure from this dominant forest floor moss.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126916","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Age-specific and season-specific mollusk damage to seedlings of grassland Asteraceael","authors":"U. Scheidel, H. Bruelheide, H. Bruelheide","doi":"10.2307/4126915","DOIUrl":"https://doi.org/10.2307/4126915","url":null,"abstract":"seedlings of the montane C. pseudophrygia and the closely related, widely distributed C. jacea revealed similar growth patterns and nearly the same damage, and therefore gave no indication that the lower altitudinal distribution limit of C. pseudophrygia may be caused by a more severe seedling herbivory. In contrast to Centaurea, the highly palatable Arnica montana seedlings were completely consumed within a few days after transplantation, irrespective of age class and without any regeneration events, supporting previous hypotheses that mollusk herbivory is a limiting factor for the geographical range of Arnica montana. In general, the results confirm that a high sampling resolution in time is of great importance to detect agespecific mortality factors in plant population studies.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126915","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of climate factors on demographic changes in the New York populations of the federally-listed Phyllitis scolopendrium (L.) Newm. var. americana","authors":"N. Kelsall, C. Hazard, D. Leopold, C. Hazard, D. Leopold, J. Torrey","doi":"10.2307/4126917","DOIUrl":"https://doi.org/10.2307/4126917","url":null,"abstract":"KELSALL, N., C. HAZARD, AND D. J. LEOPOLD (Department of Environmental and Forest Biology, SUNY College of Environmental Science and Forestry, 1 Forestry Drive Syracuse, New York 13210). Influence of climate factors on demographic changes in the New York populations of the federally-listed Phyllitis scolopendrium (L.) Newm. var. americana J. Torrey Bot. Soc. 131:161-168. 2004.-Approximately 92% of the U.S. population of American hart's-tongue fern (Phyllitis scolopendrium var. americana) is found in Onondaga and Madison counties, New York, in 17 distinct colonies. All New York colonies have been periodically censused since 1916, though rarely in the same year. This study examines census data of the total New York population during and following the severe drought of 1999 and during the summers of 2000 and 2002. Additionally, the long-term (1922-2002) census data of seven colonies are examined relative to climate data for the same period. The total New York population has declined overall since the last previous census in 1995. No climate variables explained more than 23% of variation in population size of any growth phase. The lack of controlling, largescale climate factors suggests that the distribution of hart's-tongue fern in New York is determined mostly by the occurence of habitat capable of buffering climatic fluctuations. Future work should combine small-scale habitat and large-scale climate factors in any analysis.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126917","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compressive/tensile stresses and lignified cells as resistance components in joints of Opuntia ficus-indica and Opuntia parryi var. parryi (Cactaceae)","authors":"L. Evans, J. Pancrudo, K. Lagrazon, Z. Kahn-Jetter, B. Litkouhi","doi":"10.2307/4126912","DOIUrl":"https://doi.org/10.2307/4126912","url":null,"abstract":"to being separated from the plant. Bending stress (due solely to the weight of the branches) was the predominant stress (mean bending stresses were 167 and 383 kPa for 0. ficus-indica and 0. parryi var. parryi, respectively) between stem segments. Axial, shear, and torsion stresses were relatively low compared with bending stresses for both species. Data of 0. ficus-indica and 0. parryi var. parryi show that 23.6 and 25.3% of tensile portions of joints were composed of lignified xylem cells, respectively, while compressive portions of the same joints had only 10.8 and 14.7% lignified xylem cells, respectively. The relative radial positions of lignified xylem cells for compressive, tensile and lateral portions of joints for 0. ficus-indica and 0. parryi var. parryi were analyzed. In general, lignified xylem cells were closer to the external surface in tensile tissues than in compressive and lateral tissues of joints. Thus, lignified xylem cells are located in a position to provide a high level of resistance to bending. Maximum bending stresses were positively related with amounts of lignified xylem cells in joints for both species. For 0. ficus-indica the best-fit line was y = 1.48 x + 24.2 (P = 0.012) with an r2 = 0.76. For 0. parryi var. parryi, the best-fit line was y = 54.0 x - 11.7 (P = 0.01) with an r2 = 0.92. The 1.48 slope value for 0. ficus-indica was low compared with the 54.0 slope value for 0. parryi var. parryi. Large slope values for a species may reflect a greater ability of lignified xylem cells to resist stress. In five Opuntia species for which data are available, there was a strong negative relationship between slope values and joint diameter. However, high slope values occurred in species with more horizontal stem segments. Overall, these results show bending stress is the main stress between stem segments, lignified xylem cells in stem joints provide the main resistance to joint stresses, and slope values of stress versus amounts of lignified xylem cells may be related to plant morphology.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126912","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproductive biology of Vincetoxicum rossicum (Kleo.) Barb. (Asclepiadaceae), an invasive alien in Ontario'","authors":"M. Denis, N. Cappuccino","doi":"10.2307/4126923","DOIUrl":"https://doi.org/10.2307/4126923","url":null,"abstract":"ST. DENIS, M. AND N. CAPPUCCINO (Department of Biology, Carleton University, Ottawa, Ontario, K1S 5B6 Canada). Reproductive biology of Vincetoxicum rossicum (Kleo.) Barb. (Asclepiadaceae), an invasive alien in Ontario. J. TORREY BOT. SOC. 131:8-15. 2004.-We investigated the reproductive biology of the alien invasive vine Vincetoxicum rossicum (Asclepiadaceae) and evaluated pollinator visitation rate in the field, evidenced by missing pollinaria, to flowers of isolated plants and those of plants in dense monocultures. Flowers in dense monocultures were visited less frequently than those on isolated plants surrounded by old-field grasses. Visited flowers were more likely to produce fruit and those fruits contained more polyembryonic seeds. However, a greenhouse experiment in which we crossor self-pollinated flowers revealed no difference in fruit set, seed production, seed weight or embryony. This suggests that the higher fruit set and greater polyembryony of visited flowers in the field was not the consequence of visitation, but may have been the result of floral visitors having chosen the most vigorous flowers. Day-old flowers emasculated in the greenhouse experiment occasionally produced a fruit, indicating that the germination of self-pollen begins the day a flower opens. The ability to produce large numbers of selfed seeds is no doubt advantageous to this highly invasive asclepiad.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126923","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Factors controlling the fire-induced flowering response of the federally endangered Schwalbea americana L. (Scrophulariaceae)1","authors":"A. H. Norden, L. Kirkman, J. Jones, L. Kirkman","doi":"10.2307/4126924","DOIUrl":"https://doi.org/10.2307/4126924","url":null,"abstract":"NORDEN, A. H. AND L. K. KIRKMAN (J. W. Jones Ecological Research Center, Rt. 2 Box 2324, Newton, GA 39870-9651). Factors controlling the fire-induced flowering response of the federally endangered Schwalbea americana L. (Scrophulariaceae). J. Torrey Bot. Soc. 131:16-22. 2004.-The fire-maintained longleaf pine ecosystem of the southeastern Coastal Plain harbors nearly 200 rare and endangered plant species, many of which depend on frequent fire for persistence. One such fire-dependent species is the federally endangered hemiparasite, Schwalbea americana L. (Scrophulariaceae). Regardless of season of burn, fire stimulates flowering and subsequent seed production in this species, but the specific mechanisms involved in this fire-induced flowering response are unknown. The purpose of this study was to determine the factors controlling the flowering response to fire. Using experimental treatments in the field and greenhouse, we examined the effect of variables associated with fire that may influence flowering of S. americana. Our field treatments included fire, shading immediately following fire, stem clipping plus competing vegetation exclusion, and mowing plus raking. Greenhouse treatments consisted of a gradient of light levels plus stem clipping. Our findings indicate that flowering, and subsequent viable seed production, is stimulated by a combination of clipping and increased light. These results suggest alternative management options for S. americana during years in which prescribed fire is not feasible. If prescribed fire is not an option, we suggest that mowing plus raking could be used as a temporary means to stimulate flowering and promote seed production and future seedling establishment.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126924","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Colonization of old fields by trees vs. shrubs: seed dispersal and seedling establishment1","authors":"S. Gardescu, P. Marks","doi":"10.2307/4126928","DOIUrl":"https://doi.org/10.2307/4126928","url":null,"abstract":"A. rubrum, 0.7 for F. americana, vs. 0 to 0.02 for the shrubs). For the trees, but not the shrubs, both seed input and seedling emergence in the fields showed a strong relationship to seed source abundance along the field edges, using index values based on the distances from potential source plants. Results of seed augmentation experiments showed that seedling emergence was strongly limited by seed input, but secondarily by environment; more C. racemosa emerged in moister plots and more F. americana and V. dentatum under short vegetation. Once established, seedlings of the shrubs often survived better and grew faster than did the tree seedlings. As a result of net overall differences in seedling emergence and survival, the number of seeds required to get one surviving fifth-year seedling was lowest for the shrubs (20 to 35 seeds), somewhat higher for F. americana (55), and highest for A. rubrum (326).","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126928","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Salt spray effects on forest succession in rare coastal sandplain heathlands: evidence from field surveys and Pinus rigida transplant experiments'","authors":"M. Griffiths, C. Orians, M. Griffiths","doi":"10.2307/4126925","DOIUrl":"https://doi.org/10.2307/4126925","url":null,"abstract":"GRIFFITHS M. E. AND C. M. ORIANS (Department of Biology, Tufts University, Medford, MA 02155). Salt spray effects on forest succession in rare coastal sandplain heathlands: evidence from field surveys and Pinus rigida transplant experiments. J. Torrey Bot. Soc. 131: 23-31. 2004.-Coastal sandplain heathland is a rare ecosystem maintained by recurrent disturbances and chronic abiotic stress. In areas with low disturbance or stress, heathland communities are succeeded by tree species, such as Pinus rigida, that outcompete native heathland plants. We propose that salt spray is an important natural abiotic stress factor that helps to maintain heathlands near the coast by slowing tree succession. We investigated whether salt spray inhibits succession in heathlands on Martha's Vineyard, Massachusetts, by surveying natural field distributions of species and by quantifying the survival and growth of P rigida seedlings transplanted at different distances from the ocean. Tree species did not grow in areas with high salt spray and multivariate analyses identified salt spray as an important ecological factor influencing species distributions in coastal heathlands. Although transplanted P. rigida seedlings exhibited low mortality close to the ocean, they exhibited higher water stress and needle necrosis as well as inhibition of growth, suggesting that salt spray may be important in suppressing trees close to the","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126925","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Response of forest understory vegetation to a major ice storm","authors":"Angela T. Darwin, D. Ladd, Robert Galdins, Thomas A. Contreras, L. Fahrig","doi":"10.2307/4126927","DOIUrl":"https://doi.org/10.2307/4126927","url":null,"abstract":"DARWIN, A.T., D. LADD, R. GALDINS, T. A. CONTRERAS AND L. FAHRIG (Dept. of Biol., Carleton University, Ottawa, ON, Canada KiS 5B6). Response of forest understory vegetation to a major ice storm. J. Torrey Bot. Soc. 131:45-52. 2004.-In January of 1998, Ottawa, Ontario was hit with a major ice storm. Detailed pre-storm vegetation data had been collected in 1997 in 164 forest interior sampling plots across a 3,000 km2 region. These data included information on shrubs/saplings, woody seeds and seedlings, herbaceous seeds and ground cover, and canopy cover. For the four growing seasons following the ice storm (1998-2001), we resampled the same 164 plots. In addition, in 1998 we estimated an ice storm damage index for each plot, and the volume of downed coarse woody debris due to the ice storm in each plot. The objectives of this paper were to examine changes in shrubs/saplings and ground vegetation in response to ice storm damage over the four-year period following the storm. Contrary to our initial expectations, we found that woody seedlings showed a large decrease in density immediately following the storm (1998). Woody seedling density recovered to pre-storm levels by 2001. We hypothesize that the decrease in woody seedling density resulted from reduced seedling germination due to lower light availability on the forest floor, which resulted from the large amount of woody debris created by the storm. We also found that shrub/sapling counts showed a large increase in 1999, most likely due to increased light to the understory, due to opening of the upper canopy. Herbaceous cover increased from 1998 to 2000, but returned to pre-storm levels the following year (2001). The between-plot variation in these understory changes was positively correlated to plot damage from the ice storm, indicating that they resulted from the storm. Overall, it appears that the forest understory plant structure is rapidly returning to pre-ice storm conditions.","PeriodicalId":49977,"journal":{"name":"Journal of the Torrey Botanical Society","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2307/4126927","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69302824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}