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Rebecca J. Howard - One of the best experts on this subject based on the ideXlab platform.

  • Response of Schoenoplectus acutus and Schoenoplectus californicus at Different Life-History Stages to Hydrologic Regime
    Wetlands, 2015
    Co-Authors: Taylor M. Sloey, Rebecca J. Howard, Mark W. Hester
    Abstract:

    For wetland restoration success to be maximized, restoration managers need better information regarding how the frequency, depth, and duration of flooding affect soil chemistry and the survival, growth, and morphology of targeted plant species. In a greenhouse study we investigated the impact of four different flooding durations (0 %, 40 %, 60 %, and 100 %) on soil physicochemistry and the responses of seedlings and adults of two species of emergent wetland macrophytes commonly used in restoration efforts (Schoenoplectus acutus and Schoenoplectus californicus). The longest flooding duration, which created more reducing soil conditions, resulted in significantly reduced survival of S. acutus adults (34 ± 21 % survival) and complete mortality of seedlings of both species. Schoenoplectus californicus adults exhibited higher flooding tolerance, showing little impact of flooding on morphology and physiology. A companion field study indicated that S. californicus maintained stem strength regardless of flooding duration or depth, supporting the greenhouse study results. This information serves to improve our understanding of the ecological differences between these species as well as provide restoration managers with better guidelines for targeted elevation and hydrologic regimes for these species in order to enhance the success of restoration plantings and better predict restoration site development.

  • Intraspecific variation in growth of marsh macrophytes in response to salinity and soil type: Implications for wetland restoration
    Estuaries and Coasts, 2010
    Co-Authors: Rebecca J. Howard
    Abstract:

    Abstract Genetic diversity within plant populations can influence plant community structure along environmental gradients. In wetland habitats, salinity and soil type are factors that can vary along gradients and therefore affect plant growth. To test for intraspecific growth variation in response to these factors, a greenhouse study was conducted using common plants that occur in northern Gulf of Mexico brackish and salt marshes. Individual plants of Distichlis spicata, Phragmites australis, Schoenoplectus californicus, and Schoenoplectus robustus were collected from several locations along the coast in Louisiana, USA. Plant identity, based on collection location, was used as a measure of intraspecific variability. Prepared soil mixtures were organic, silt, or clay, and salinity treatments were 0 or 18 psu. Significant intraspecific variation in stem number, total stem height, or biomass was found in all species. Within species, response to soil type varied, but increased salinity significantly decreased growth in all individuals. Findings indicate that inclusion of multiple genets within species is an important consideration for marsh restoration projects that include vegetation plantings. This strategy will facilitate establishment of plant communities that have the flexibility to adapt to changing environmental conditions and, therefore, are capable of persisting over time.

  • Clonal variation in response to salinity and flooding stress in four marsh macrophytes of the northern gulf of Mexico, USA
    Environmental and Experimental Botany, 2006
    Co-Authors: Rebecca J. Howard, Patricia S. Rafferty
    Abstract:

    Intraspecific variation in stress tolerance can be an important factor influencing plant population structure in coastal wetland habitats. We studied clones of four species of emergent marsh macrophytes native to the northern coast of the Gulf of Mexico in Louisiana, USA, to examine variation in response to salinity and flooding stress under controlled greenhouse conditions. Clones of Distichlis spicata, Phragmites australis, Schoenoplectus californicus, and Schoenoplectus robustus were collected across the coastal zone of Louisiana. After vegetative propagation through at least three generations to remove acclimation to field conditions, four to six clones of each species were selected for use in the experiment. Treatments consisted of three salinity levels and two water depths, and species were assigned to either a brackish marsh (P. australis, S. californicus) or salt marsh (D. spicata, S. robustus) group for treatment application. Treatment effects on plant growth (stem number, total height, and mean height, and aboveground and belowground biomass) were examined, and physicochemical characteristics within treatments (redox potential, and interstitial water pH, salinity, temperature, and nutrients) were monitored. Clonal variation in growth was indicated in all species, and was more pronounced in D. spicata and P. australis than in S. californicus and S. robustus. Distichlis spicata and P. australis clones were assigned to relative categories of low, intermediate, and high tolerance to the imposed stressors. Similar generalizations on clonal stress tolerance were not possible for the two Schoenoplectus species. Overall species response to imposed stressors was also identified through non-statistical comparisons. Phragmites australis was more tolerant than S. californicus of increased salinity. Distichlis spicata was more tolerant of increased salinity but less tolerant of increased water depth than was S. robustus. Our results suggest that information on species and clone variations in growth and tolerance to salinity and flooding stressors can be used to select a variety of plant materials suitable for wetland restoration projects.

Fred Rumsey - One of the best experts on this subject based on the ideXlab platform.

J. Browning - One of the best experts on this subject based on the ideXlab platform.

  • Studies in Cyperaceae in southern Africa. 25: Schoenoplectus tabernaemontani
    South African Journal of Botany, 1995
    Co-Authors: J. Browning, K.d. Gordon-gray, S. Galen Smith
    Abstract:

    Southern African plants previously known as Schoenoplectus lacustris (L.) Palla or Scirpus lacustris L. are recircumscribed morphologically, and distributional and habitat details are given. They are transferred to Sch. tabernaemontani (C.C. Gmel.) Palla, which includes Sch. validus (Vahl) A. Love & D. Love, and with which they fit more precisely. The broad conception of Scirpus lacustris L. as a complex species incorporating S. tabernaemontani C.C. Gmel. is more effectively treated as several individual species, in many cases linked in certain parts of their ranges by natural hybrids.

  • Studies in Cyperaceae in southern Africa 23: a reassessment of Schoenoplectus litoralis, Sch. subulatus and Scirpus pterolepis
    South African Journal of Botany, 1994
    Co-Authors: J. Browning, K.d. Gordon-gray, C.j. Ward
    Abstract:

    A summary of the history of the taxon currently known in southern Africa as Schoenoplectus litoralis (Schrad.) Palla is given. The epithet litoralis is no longer applicable to these plants. A case is made for the recognition of two species in southern Africa, namely Schoenoplectus subulatus (Vahl) K. Lye, limited to Namibia, and the widespread Scirpus pterolepis (Nees) Kunth that, with transference to Schoenoplectus and because of priority, must become Schoenoplectus scirpoideus (Schrad.) J. Browning comb. nov.

  • Studies in Cyperaceae in southern Africa. 20: Changed status of Schoenoplectus corymbosus var. brachyceras and report of hybrids
    South African Journal of Botany, 1992
    Co-Authors: J. Browning
    Abstract:

    1. Schoenoplectus corymbosus (Roth ex Roem. & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye is reverted to specific status as S . brachyceras (A. Rich.) K. Lye. 2. Suspected natural hybridization between Schoenoplectus brachyceras and S . decipiens (Nees) J. Raynal is reported. Variants (interpreted as introgressives) occurred together with both putative parents under vlei conditions near Wakkerstroom, Transvaal, South Africa. Significant morphological features that support this hybridization are described and illustrated.

  • Studies in Cyperaceae in southern Africa 17: An examination of Schoenoplectus muricinux (C.B. CI.) J. Raynal sensu lato
    South African Journal of Botany, 1991
    Co-Authors: J. Browning
    Abstract:

    Herbarium material of the sub-tropical and southern African species, Schoenoplectus muricinux (C.B. CI.) J. Raynal sensu lato was found to comprise three different entities. Two of these are Schoenoplectus muricinux sensu stricto and Schoenoplectus muriculatus (Kuekenth.) J. Browning comb. nov., syn. Scirpus muriculatus Kuekenth. The third, with a distribution restricted to the geographic area of Maputaland, Natal, is Schoenoplectus confusus (N.E. Br.) K. Lye subsp. natalitius J. Browning (subsp. nov.). The new subspecies is established on the basis of morphological differences from the typical subspecies and its two varieties. Schoenoplectus confusus has not previously been recorded for southern Africa. A key to identification, formal descriptions, distribution maps and illustrations are provided for the two species and one subspecies in southern Africa. Schoenoplectus muricinux s.l. is briefly surveyed in sub-tropical Africa.

  • Studies in Cyperaceae in southern Africa. 18: A re-appraisal of Schoenoplectus Corymbosus
    South African Journal of Botany, 1991
    Co-Authors: J. Browning
    Abstract:

    Material in South African herbaria (and some from other parts of Africa and India) of the Indian and African species, Schoenoplectus corymbosus (Roth ex Roem. & Schult.) J. Raynal was examined. Two varieties, the typical var. corymbosus and var. brachyceras (A. Rich.) K. Lye, are recognized for southern Africa. These are the same as those recognized by Haines and Lye (1983) for East Africa, but some alternative criteria are proposed for their recognition. The development of hypogynous bristles and vegetative proliferation are briefly discussed. The history of the species is summarized, and a key to identification, formal descriptions, a distribution map and illustrations are provided.

Hans Brix - One of the best experts on this subject based on the ideXlab platform.

  • Alum application to improve water quality in a municipal wastewater treatment wetland: Effects on macrophyte growth and nutrient uptake
    Chemosphere, 2010
    Co-Authors: Lynette M. Malecki-brown, John R. White, Hans Brix
    Abstract:

    Application of low doses of alum to treatment wetlands to reduce elevated outflow winter phosphorus concentrations were tested in mesocosms vegetated with either Typhadomingensis, Schoenoplectus californicus, or submerged aquatic vegetation (SAV) (Najas guadalupensis-dominated). Alum was pumped to experimental units at a rate of 0.91 g Al m(-2) d(-1) and water quality monitored for 3 months. The alum application significantly improved the outflow water quality and overall the growth of the plants was unaffected by the alum application. Biomass and growth varied between species and through time, but no significant effects of alum application were detected. The concentrations of nutrients and mineral elements in the aboveground tissues differed between species and over time, but only the concentration of Al in plant tissue was increased by alum additions. The concentration of Al was 50-fold higher in alum-treated SAV as compared to the control, and in Typha and Schoenoplectus the concentrations were 4- and 2-fold, higher, respectively. The N/P ratios in the plant tissues were low (

Heather Carpenter - One of the best experts on this subject based on the ideXlab platform.