    [From the U.S. Government Printing Office, www.gpo.gov]

          --' ter for Marine and Coastal Studies- North Carolina State University
     Coastal Zone
     Information    3
      Center

                 Dune Stabilization with Panicum amarum
                      Along the North Carolina Coast

                                                    COASTAL ZONE
                                                    INFORMATM  CENTER

                                      By                 MAY 2 6 1977
                         E. D. SENECA, W. W. WOODHOUSE, JR.,
                                and S. W. BROOME

                                REPORT NO. 77-1
                                  UNC-SG-77-03
                                FEBRUARY, 1977

     C

     57.2
      N6
     no. 77-03

             COASTAL ZOE
             JNF~Timo CENTER

    CENTER FOR MARINE AND COASTAL STUDIES
      NORTH CAROLINA STATE UNIVERSITY
          RALEIGH, NORTH CAROLINA

    Dune Stabilization with Panicum amarum
       Along the North Carolina Coast

                    by

     E. D. Seneca, W. W. Woodhouse, Jr.,
             and S. W. Broome

              Report No. 77-1
               UNC-SG-77-03

               February, 1977

                                               COASTAL ZONE
                                               INEhHUNU ~CENTER
                           ACKNOWLEDGEMENTS

    This publication is a reprint of Miscellaneous Report No. 76-3 prepared
    by the Coastal Engineering Research Center, U. S. Army Corps of Engineers
    dated February, 1976. In addition to funding by the North Carolina State
    Coastal Research Program, financial support was provided by the Univer-
    sity of North Carolina Sea Grant College Program, Office of Sea Grant,
    NOAA, U.S. Department of Commerce under Grant Number 2-35178, and the
    North Carolina Department of Administration. The U.S. Government is
    authorized to produce and distribute reprints for governmental purposes
    notwithstanding any copyright that may appear hereon.

                                     PREFACE

        This report is published to assist coastal engineers in dune stabili-
    zation by the establishment and development of vegetation. The work was
    carried out under the coastal ecology research program of the U.S. Army
    Coastal Engineering Research Center (CERC).

        The report was prepared by E.D. Seneca, Associate Professor of Botany
    and Soil Science; W.W. Woodhouse, Jr., Professor of Soil Science; and
    S.W. Broome, Research Associate in Soil Science; North Carolina State
    University, Raleigh, North Carolina, under CERC Contract No. DACW72-73-
    C-0025. Support was received from the North Carolina Sea Grant Program,
    Office of Sea Grant, National Oceanic and Atmospheric Administration,
    Department of Commerce, Grant No. 2-35178 and 04-3-158-40; the North
    Carolina Coastal Research Program; and the North Carolina Agricultural
    Experiment Station.

        The authors express appreciation to personnel of the Cape Hatteras
    and Cape Lookout National Seashores, National Park Service, for permission
    to obtain the original transplants and for cooperation during the study.
    Special 'thanks are due D.M. Bryan, C.L. Campbell, Jr., and U.O. Highfill
    for their assistance in all phases of the fieldwork, and to D.W. Woodard,
    marine biologist, formerly of CERC, for his encouragement throughout the
    course of this study.

       Mr. R.M. Yancey, Chief, Ecology Branch, was the CERC contract monitor
    for the report, under the general supervision of Mr. R,P. Savage, Chief,
    Research Division.

        Comments on the publication are invited.

       Approved for publication in accordance with Public Law 166, 79th
    Congress, approved 31 July 1945, as supplemented by Public Law 172, 88th
    Congress, approved 7 November 1963.

                                                 JMS L. TRAYB
                                               Colonel, Corps    Engineers
                                              Commander and   rector

                                          CONTENTS

                                                                                    Page

      I INTRODUCTION.                                                    .........................7

     II METHODS ..                                                       ..........................9
            1. Nursery Propagation.                                       ...................9
            2. Planting at Duck, North Carolina .                        .........._9
            3. Planting at Drum Inlet, North Carolina.                    .........14

    III RESULTS AND DISCUSSION ..                                        ...................16
            1. Duck Planting.                                             ......................16
            2. Drum Inlet Planting.                                      ...................20

     IV SUMMARY AND CONCLUSIONS.                                        ...................40

         LITERATURE CITED.                                              .......................42

                                           TABLES

     I Mean number of leaves, mean number of culms, and mean cover
         per 14-meter transect at Duck, 1973.                           .............18

     2 Stand count by treatment for certain plots at Duck, 1973  ....19             .

     3 Invading flowering plants to the experimental planting at
         Duck, June and September 1974.                                  ................22

     4 Frequency for 13 plant species at Duck, 1974.                     .........23

     5 Mean estimated cover for all plant species at Duck, 1974  ....24

     6 Mean aboveground biomass for five plant species at
         Duck, 1974.                                                     ..........................25

     7 Mean number of leaves per transect for four dune grasses
          at Drum Inlet, 1973.                                            .....................28

     8 Mean number of culms per transect for four dune grasses
          at Drum Inlet, 1973.                                            .....................29

     9 Mean cover per transect for four dune grasses at
          Drum Inlet, 1973.                                               .......................30

    10 Frequency for six dune plants at Drum Inlet, 1974.                .......32

    11 Mean estimated cover for all plant species at Drum
          Inlet, 1974 ..........................3

                                              4

                                 CONTENTS

                             TABLES-Continued
                                                                Page
    12  Mean aboveground biomass for five dune plants at Drum
        Inlet, 1974 ..........................35

    13 Cumulative mean volume of sand accumulated over 3-, 15-,
        and 27-month periods at Drum Inlet ...............38

                                 FIGURES

    1 Panicum craumaw (bitter panicum) near Duck ............                 8

    2 Map of bitter panicum sites of origin, nursery, and
        experimental planting sites ..................10

    3 Bitter panicum nursery at Clayton, North Carolina, 1972,
        6 months after establishment ..................11

    4 Bitter panicum transplants; pruned and unpruned ......... 12

    5 Experimental planting site at Duck, June 1973 ..........13

    6  Experimental planting site at Drum Inlet, March 1973 ...... 15

    7  Experimental planting site at Duck, September 1973 ....... 17

    8 Experimental planting site at Duck, June 1974 .......... 21

    9  Experimental planting site at Duck, September 1974 ....... 21

    10 Sand accumulation on the sound side of 0.61-meter fence at
        Drum Inlet planting site, May 1973 ...............27

    11  Experimental planting of American beachgrass, bitter
        panicum, and sea oats at Drum Inlet ..............27

    12 Bitter panicum treatment in experimental planting at
        Drum Inlet, September 1973 . . . ................31

    13  Bitter panicum treatment in experimental planting at
        Drum Inlet, October 1974 ....................31

    14 Experimental planting of American beachgrass, bitter
        panicum, and sea oats at Drum Inlet, October 1974 .......            33

    15 Hatteras beachgrass treatment in experimental planting at
        Drum Inlet ...........................36

                                   5

                                    CONTENTS

                                FIGURES-Continued
                                                                         Page
    16 Mean dune cross sections in meters above mean sea level
        for seven treatments at Drum Inlet, 1973 to 1975 . . . . . . . . 39

              DUNE STABILIZATION WITH PANICUM AMARUM ALONG THE
                          THE NORTH CAROLINA COAST

                                     by

                      E.D. Seneca, W.W. Woodhouse, Jr.,
                               and S.W. Broome

                              I. INTRODUCTION

         The perennial coastal dune grass Panicum amarumn Ell. (bitter
    panicum) (Fig. 1) is distributed on foredunes in a discontinuous manner
    from New England to Florida, and around the gulf to Texas. The
    taxonomy, distribution, and habitat preferences of bitter panicum have
    been described in a study by Palmer (1975). She indicated that this
    grass is a sterile form of Panicum amarulum Hitchc. & Chase (shoredune
    panicum), and is well adapted to the foredune habitat. The shoot and
    rhizome systems have the potential to produce new shoots and roots at
    the respective nodes as described by Dahl, et al. (1974). The growing
    season (aboveground growth) along the North Carolina coast is from May
    through October, which is about 2 to 3 months less at this latitude than
    that of Ammophila breviligulata Fern. (American beachgrass). However,
    unlike American beachgrass which is a temporary stabilizer and often
    loses dominance within 5 to 10 years along the southeastern coasts,
    bitter panicum forms a part of the permanent cover along with UnioZa
    paniculata L. (sea oats).

         There is no universal agreement among dune researchers as to the
    reason for the discontinuous distribution and, until recently, for the
    relative sparsity of bitter panicum along much of the coast. Some
    researchers believe that this grass was grazed out by free-roving
    livestock, while others feel that certain environmental factors are
    responsible. Dahl, et al. (1974) noted that it is preferred by cattle
    to several other dune grasses on the Texas coast. Whatever the
    limiting factors were in the past, within recent years established
    stands of bitter panicum on the North Carolina coast have spread and new
    areas are being colonized.

         Earlier dune building and stabilization studies along the North
    Carolina coast have concentrated on American beachgrass (Woodhouse and
    Hanes, 1967) and sea oats (Woodhouse, Seneca, and Cooper, 1968).
    Although American beachgrass is a good dune builder at this latitude, it
    is attacked by a scale insect, Eriococcus carolinae Williams (Campbell
    and Fuzy, 1972), is susceptible to the mushroom-forming fungus,
    Marasmius sp. (Lucas, et al., 1971), and appears less drought tolerant
    than sea oats. A controlled environment study with seedlings grown from
    seed collected along the Atlantic and gulf coasts suggested that
    temperature is a major factor responsible for the observed replacement
    of American beachgrass by sea oats south of the Virginia-North Carolina
    line (Seneca, 1972). A recent study on the Texas coast established that
    bitter panicum and sea oats were the two best adapted plants tested for

                                     7

                                                                                                        *   ~~~~    *~~~~? ~ ~ ~

              i�  �  : ::    ;  :::::#--                  v $7

                         i: ~  ~      ~

                         i~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~*.* y::
           i~~~~                1

    Figure~ :~; 1. .aiw    m       m(itrpncu)na    uk                            ot       aoia

                                    i:~~~~~

    dune building and sand stabilizing (Dahl, et al., 1974). In that study,
    American beachgrass was not successfully established, and bitter
    panicum was more successfully transplanted and easier to procure and
    handle than sea oats.

         This study began in the spring of 1972 to determine the dune
    building and sand stabilizing potentials of bitter panicum along the
    North Carolina coast.

                                II. METHODS

    1. Nursery Propagation.

         Plants of bitter panicum were collected from Hatteras Island and
    Ocracoke Island, North Carolina, in March 1972, to establish a nursery
    at Clayton, North Carolina (Fig. 2). Single culm (stem) plants were
    spaced 0.6 meters apart in rows 1.1 meters apart. These transplants
    were cultivated to control weeds, and fertilized in mid and late summer.
    By fall, there were about 10 culms for every original one (Fig. 3).
    This number coverts to about 660 culms per are (100 square meters) in
    the first year. By the end of the second growing season there were
    about 1,650 culms per are.

         Field experiments with these plants began in the spring of 1973,
    at Duck and Drum Inlet (Fig. 2). About 2 man-hours were required to
    prepare 1,000 plants for field planting. Processing included digging,
    breaking apart into usable transplants (Fig. 4), dipping in a clay
    slurry, and packaging in reinforced paper to prevent desiccation.
    These plants and two other dune grasses were used to test the dune
    stabilization effectiveness of mixed species plantings with primary
    emphasis on bitter panicum.

    2. Planting at Duck, North Carolina.

         The experimental planting at Duck was located about 300 meters
    inland on a relatively broad, high, unstabilized sandy site (Fig. 5),
    which is a part of the barrier island site of the Coastal Engineering
    Research Center (CERC) Field Research Facility. This area was once part
    of an aerial practice gunnery range and was largely denuded of
    vegetation. Stabilization at this site became more of a concern than
    dune building.

         The planting was established on 4 and 5 April 1973, using
    mechanical procedures developed earlier (Woodhouse and Hanes, 1967).
    Six planting treatments were replicated three times in 14- by 50-meter
    plots. Each plot consisted of plants in 14 rows running toward the
    ocean with 0.9 meters between rows and 0.9 meters between plants within
    rows except for certain rows in which bitter panicum plants were buried.

         The six treatments consisted of: (a) nursery transplants of
    bitter panicum from Hatteras Island stock; (b) nursery transplants of

                                      9

             EASTERN NORTH CAROLINA

                                                  4-DUCK
                                                     360 N. Lat.

    0 CLAYTON

                                                        ISLAND
                                                  ,,...  HATTERAS

                                                         HATTERAS
                                                OCRACOKE ISLAND
                                              35 N. Lat.

                                       CAPE LOOKOUT

               340 N. Lat.

              CAPE FEAR

     Figure 2o  Map of bitter panicum sites of origin (Hatteras and Ocracoke
              Islands), nursery (Clayton), and experimental planting sites
              (Duck and Drum Inlet).

                                 I0

    Figure 3. Bitter panicum nursery at Clayton, North Carolina, September
               1972, 6 months after establishment0

                                       II

    Figure 4.  Bitter panicum transplants; top transplant pruned to
               facilitate machine planting, bottom transplant unpruned.

                                    12

                                    - - -~~~~~~~~~~~~~~~

    Figure S. Experimental planting site at Duck, North Carolina, June 1973.

                                           13

    bitter panicum from Ocracoke Island stock; (c) nursery transplants of
    Hatteras beachgrass, a locally adapted strain of American beachgrass;
    (d) a combination of transplants used in (a) and sea oats from Duck;
    (e) a combination of transplants used in (a) and (c); and (f) a
    combination of transplants used in (a), (c), and (d).
         The planting was sampled in October 1973 and 1974. Nine 14-meter
    transects were sampled in 1973, across the width of each of the 18
    experimental plots. A modification of the line intercept technique was
    used to determine number of leaves, culms (stems), and percentage of the
    length of the transect actually occupied by shoots (plant cover) for
    American beachgrass, bitter panicum, and sea oats. A stand count was
    also conducted on selected plots to compare the number of living bitter
    panicum plants per row where the entire transplant was buried in a furrow
    with those established by the conventional upright planting technique.
         Five 1-square-meter quadrats (subplots) were sampled in 1974, in
    each of the 18 plots. The different species present and the estimated
    combined cover were recorded for each plot. The aboveground vegetation
    was clipped for selected species for subsequent biomass determinations,
    and dried at 70� Celsius prior to dry weight determinations for
    American beachgrass, bitter panicum, shoredune panicum, Triplasis
    purpurea (Walt.) Chapm. (purple sandgrass), and sea oats.
         The planting was observed periodically and fertilized at the rate
    of 56 kilograms of nitrogen per hectare (one time the first growing
    season and three times the.second).

    3. Planting at Drum Inlet, North Carolina.

         The experimental planting at Drum Inlet was located about 100 meters
    inland on the level strand 1 or 2 meters above the normal mean high tide
    level (Fig. 6). There were scattered clumps of native Spartina patens
    (Ait.) Muhl. (saltmeadow cordgrass) and sea oats throughout the planting
    site. Since the study was concerned with dune building as well as
    stabilization at this site, a 0.61-meter sand fence (Fig. 6) was
    constructed in February 1973 to accumulate a ridge of sand before
    planting.
         The planting was established during 13 to 15 March 1973, using
    mechanical procedures cited earlier. The variably spaced, mixed
    species planting was designed to determine dune building and dune
    stabilization response by three species of grass with primary emphasis
    on bitter panicum. Seven treatments consisted of nursery-grown
    transplants of: (a) NJ-327 American beachgrass; (b) Cape American
    beachgrass (Gaffney and Duell, 1974) formerly NJ-390; (c) Hatteras
    beachgrass, a locally adapted strain of American beachgrass; (d)
    bitter panicum from Hatteras Island; (e) a combination of (c) and
    (d); (f) a combination of (d) and sea oats from Drum Inlet; and (g) a
    combination of (c), (d), and (f). One row of sea oats and two rows of
    bitter panicum (buried) ran through all plots of all treatments.
    Saltmeadow cordgrass was not planted. The planting was oriented

                                      14

    Figure 6. Experimental planting site at Drum Inlet, North Carolina,
              March 1973.

                                    15

    parallel to the beach with each treatment replicated twice by 14- by
    70-meter plots. Within these 16-row plots, the center 4 rows were
    spaced 0.46 meters apart, the 4 rows on either side of the center 4
    rows were spaced 0.76 meters apart, and the outermost 2 rows on either
    side were spaced 1.1 meters apart. In the spring of 1974, greenhouse-
    grown seedlings of sea oats were planted 1.5 meters apart on the crest
    of the dune in barren areas.

         The planting was sampled in October 1973 and 1974. The 14
    experimental plots were sampled in 1973 in the same manner as those
    at Duck except that saltmeadow cordgrass was also sampled. Eight 1-
    square-meter quadrats were sampled in 1974 on the oceanside and 8 on
    the sound side of the dune in each of the 14 plots. The plant species
    present and the estimated combined cover were recorded for each
    quadrat. The aboveground vegetation was clipped by species for
    subsequent biomass determinations, and dried at 700 Celsius before
    dry weight determinations for American beachgrass, Euphorbia
    poZygonifoZia L. (seaside spurge), bitter panicum, saltmeadow cordgrass,
    and sea oats.

         The planting was observed periodically and fertilized twice during
    the first growing season at the rate of 56 kilograms of nitrogen per
    hectare. Elevation surveys were conducted in June 1973, 1974, and
    1975, by running two cross sections per plot with a level to determine
    sand accumulation. The experimental area was also repaired in the
    spring of 1974, by filling gaps with sand and replanting barren areas.

                        III. RESULTS AND DISCUSSION

    1. Duck Planting.

         a. 1973. There was little growth in the April transplants by
    June 1973 (Fig. 5). Although much of the sand was still bare of
    vegetation in September 1973, surviving transplants of bitter panicum
    were well established and the area was becoming stabilized (Fig. 7).
    With the exception of plot 3, which was a mixed species treatment
    consisting of bitter panicum plus Hatteras beachgrass, the number of
    leaves, culms, and the cover was greater with bitter panicum than either
    of the other two dune grasses in all plots of two- and three-species
    treatments (Table 1). Only bitter panicum yielded cover values of
    more than 0.50 percent. American beachgrass and sea oats were
    initially found in scattered clumps throughout the planting site
    (Table 1).

         A count on selected plots indicated the number of living bitter
    panicum plants was greater in rows where the entire plant had been
    buried in a furrow than in rows established by the conventional upright
    planting technique (Table 2). Average percentages of living transplants
    were 31 for Hatteras beachgrass, 62 for bitter panicum, and 16 for
    sea oats. Although survival of bitter panicum was good, growth during
    the first growing season was slow compared to the other experimental

                                                                                                             * ~ ~~~~~~~~~~~~ A .
                                             Figure 7. Experimental planting site at Duck, North Carolina,

                                                  September ~? 197 3~i ?~i~i,~,~,~ ~,~                                                                      ....       ,
                                   i*',!~:~                           -4. ~ ~!ii~ i ~!~!i~17
                               ~~~                             ~                                          .       . , ii~
                                                        4   4.-  *4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~**~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~�~~~~~~~~~~~~~~~~~~~~~~~4~ ~~~ ~~~ ~~~ ~
                                                      /

                                                                      *~~~~~~~~~~~~~~~~~~~~.~~~~~~~~~                                          ~iii,?!:F~!:,C :*~,

                                                           Fiur o xprmeta latigsie tDukNrt Crlia

    *~~~~~~~etme    195

              *   ~ ~             4~xx~~4t  fT                                            i

    Table 1. Mean number of leaves, mean number of culms, and mean cover per 14-meter transect at Duck,
              North Carolina, 19731.

            Treatment          Plot No.    Mean No. leaves    Mean No. culms per             Mean cover
                                          per 14-m transect       14-m transect       per transect (percent)
                                            A2     P3      U4    A2      P3    U4           AZ    P3    U4

    Bitter panicum (Hatteras)    1         0.78  35.33   4.22  0.44  11.00  1.33            0.02  1.35  0.11
                                  7              30.78   7.67           8.22  1.33               1.17  0.23
                                 14              56.78                 14.22                     1.86

    Bitter panicum (Ocracoke)    5                46.22                 12.78                     1.55
                                 11       0.33  42.44           0.11  12.44              <0.01  1.40
                                 16       1.00  21.78  17.22  0.33   8.67  4.78           0.03  0.63  0.47

    Hatteras beachgrass            4        6.67                  2.00                      0.09
                                 12       5.89            1.11  2.33          0.33        0.14          0.03
                                 13       7.22                  2.22                      0.19

    Bitter panicum (Hatteras)
      plus                         2       0.56  11.33   5.11  0.22   4.00  1.11            0.02  0.39  0.11
    Sea oats (Duck)                9       0.44   9.00   2.44  0.22   5.00  0.56           <0.01  0.60  0.07
                                 17              32.56   1.00          10.11  0.33               1.12  0.02

    Bitter panicum (Hatteras)
      plus                         3      10.89  11.22   4.56  3.22   2.67  1.33            0.15  0.30  0.09
    Hatteras beachgrass            8        3.44  28.11   0.78  1.00   7.11  0.33           0.06  0.93  0.01
                                 15       1.89  24.56           0.78   8.78               0.03  0.92

    Bitter panicum (Hatteras)
       plus                        6       3.56  14.44            1.44   3.78               0.07  0.54
    Sea oats (Duck) plus          10        4.33  15.11   0.89  1.78   3.89  0.22           0.08  0.50   0.02
    Hatteras beachgrass           18        2.44  24.89   1.00  0.89   7.22  0.22           0.05  0.79   0.02

    1.  Based on nine transects per plot per treatment, n = 162.
    2.  Ammnophila breviligulata (American beachgrass).
    3.  Panicum amarn (bitter panicum).
    4. UnioZa panicuZata (sea oats).

                             Table 2. Stand count by treatment for certain plots at Duck, North Carolina, 1973.

                                  Treatment                      Plot No.                        Survival  (percent)
                                                                                 American              Bitter               Sea oats
                                                                                beachgrass            panicum
                                                                                                 buried2     upright3

                             Bitter panicum (Hatteras)               1                              62          56
                                                                     7
                                                                    14                             73           47
                             Bitter panicum (Ocracoke)               5                              69          50
                                                                    11
                                                                    16                             59           50
                             Hatteras beachgrass                     4
                                                                    12               36
    '0                                                               13               29
                             Bitter panicum (Hatteras) plus          2                                                          9
                             Sea oats (Duck)                         9                                                         13
                                                                    17                                                         25
                             Bitter panicum (Hatteras) plus          3
                             Hatteras beachgrass                     8
                                                                    15
                             Bitter panicum (Hatteras) plus          6
                             Sea oats (Duck) plus                   10
                             Hatteras beachgrass                    18               27             77                         16

                              1.  Number of living plants divided by the total number of possible transplants per row
                                  by standard upright planting technique.

                              2. Entire transplant buried in a furrow.

                              3. Transplant planted upright.

    planting site at Drum Inlet. There were no noticeable differences in
    the performance of the selections of bitter panicum from Hatteras and
    Ocracoke. The low survival of Hatteras beachgrass cannot be explained;
    it is possible that the transplants were initially of low vigor. The
    low survival of sea oats is consistent with results from other
    experiments and those of Dahl, et al. (1975).

         b. 1974. Plant cover was estimated to be about 70 percent in June
    1974. Of the three dune grasses planted in April 1973, only bitter
    panicum contributed an appreciable amount of this estimate (Fig. 8).
    The remainder of the cover was composed of native plants that invaded the
    planting (Table 3); a few seedlings of American beachgrass and sea oats
    were observed. Cenchrus tribuliodes L. (sand spur), Diodia teres Walt.
    (buttonweed), Oenothera humifusa Nutt. (evening primrose), and purple
    sandgrass were the most widely distributed invading species (Table 4).
    Only 0. hwnifusa is a perennial.

         By September 1974, plant cover was estimated to be about 75 percent
    (Fig. 9). Again, only bitter panicum contributed an appreciable amount
    of this estimate, with the remainder composed of the invading native
    plants (Table 3). Purple sandgrass, one of the four abundant invaders,
    was the most prominent. Although the shoots of bitter panicum were well
    developed, the rhizomes had not proliferated rapidly over the area.
    This growth response was possibly due to the lack of sand movement.
    Bitter panicum is most healthy and vigorous in areas accumulating
    moderate amounts of sand.

         Plant frequency, the percentage of sample plots in which a plant
    species occurs, is a relative measure of distribution. In the October
    sampling, values of 60 percent and above were obtained for bitter
    panicum in all plots of original planting (Table 4). However, for both
    American beachgrass and sea oats, frequency values were 60 percent or
    below in the experimental plots; in several plots these species were not
    recorded in the sample.

         Except for plot 18, cover values were 70 percent and above (Table
    5). The relatively high cover values were largely due to the invading
    species, particularly the annual, purple sandgrass.

         Bitter panicum contributed about 27 percent of the aboveground dry
    weight, and averaged about 30 grams per square meter in the plots of
    original planting, 1, 2, 3, 5, and 6, and where purple sandgrass biomass
    was also determined (Table 6). Purple sandgrass was sampled for biomass
    in only six plots, but since it was uniformly distributed it probably
    contributed at least a minimum biomass of 37 grams per square meter
    which would be more than that of bitter panicum (Table 6).

    2. Drum Inlet Planting.

         a. 1973. Survival of transplants in June 1973 was estimated at
    75 percent, except for the two rows adjacent to the 0.61-meter sand

                                    20

    Figure 8o Experimental planting site at
              Duck, North Carolina, June 1974,

    Figure 9o Experimental planting site at
               Duck, North Carolina, September
               1974.

                       21

    Table 3. Invading flowering plants to the experimental planting at
              Duck, June and September 1974.

               Name                         Growth   Abundance1      Month
                                             form                  recorded

    Ambrosia artemisiifoZia L. (ragweed)    herb    infrequent    Sept.
    Carex sp.                                sedge   rare           June
    Cenchrus tribuloides L. (sand spur)      grass   abundant       June, Sept.
    Chenopodium ambrosioides L. (Mexican-
       tea)                                  herb    rare           Sept.
    Cyperus iria L. (rice flatsedge)         sedge   rare           Sept.
    Digitaria fiZiformis (L.) Koeler
       (slender fingergrass)                 grass   infrequent    Sept.
    Diodia teres Walt. (buttonweed)          herb    abundant       June, Sept.
    Erigeron canadensis L. (horseweed)       herb    infrequent    June, Sept.
    Euphorbia poZygonifolia L. (seaside
       spurge)                               herb    common         Sept.
    GhaphaZium obtusifoZium L. (rabbit
       tobacco)                              herb    infrequent    June, Sept.
    Myrica pensylvanica Loisel. (bayberry)  shrub   rare            June, Sept.
    Oenothera humifusa Nutt. (evening
       primrose)                             herb    abundant       June, Sept.
    Panicum amaruZum Hitchc. & Chase
       (shoredune panicum)                   grass   common         June, Sept.
    PhysaZis viscosa ssp. maritima
       (M. A. Curtis) Waterfall (ground
       cherry)                               herb    infrequent    June, Sept.
    Spartina patens (Ait.) Muhl.
       (saltmeadow cordgrass)                grass   rare           June, Sept.
    TripZasis purpurea (Walt.) Chapm.
       (purple sandgrass)                    grass   abundant       June, Sept.

    1. Scale of abundance from most to least abundant: abundant, common,
        infrequent, rare.

                                      22

    Table 4.  Frequency for 13 plant species at Duck, North Carolina, 1974.

                                  u)        CA                                              CA

                                        0 co                                   '            $ O

    Treatment               Plot             .c
                                       ~No. .   C                   b 30    Cu
                                  No   C    O             b.    C 0                   Q       0  bh

    Bitter panicum
                               C7   4P.    4 10              0     00    6                      1
                                  14   40       6$0                             0   100

    Bitter panicum
       (Ocracoke)           5     2                0 60 20        20 20        80    20           80
                            11         60         80      60      1 00 4100
                            16     80           100               20    80          20 100            c
                           12     40  ;840 80   80                              20               100

                           13        20 20  100                    40                . 20        100
    Bitter panicum
       (Hatteras)              2  4      0    0       20      20   10    80               10 20
                           Sea oats0 (Duck)  9  40                10       0                     100

                           17          80     -100                 40    80    60               .100
    Bitter panicum
       (Hatteras) plus     16           803 60   100          2      0    80    20               100
    Hatteras beachgrass      4     60  100   20 80                  100          40               100
                           12     40   80         80               80           20               100    20
                          13     20        20  100                40    80    20                100
    Bitter panicum
       (Hatteras) plus      2     40  100         80 20             40    80                      80 20
    Sea oats (Duck)          9          40        100               20   100           20         100
                          17          80  -   100                 40   100    60               .100
    Bitter panicum
       (Hatteras) plus      3     60  100         60          20    40    80                 20  100
    Hatteras beachgrass      8     20  100        100                80   100                     100
                          is         100        100               40    80    20                100

    Bitter panicum
       (Hatteras) plus'   6             60        60                40    80           20        100
    Sea oats (Duck) plus   10      40   80         80               80    60           20         100   20
    Hatteras beachgrass    18           60         60                      60                     100   20

    1. The percentage of sample plots in which a species occurred, based on five 1-square-meter
        sample subplots in each replicate (plot) per treatment, n = 90.

                                   1
    Table 5.  Mean estimated cover  for all plant species at Duck,
              North Carolina, 1974.

          Treatment                         Plot No.           Mean estimated
                                                              cover (percent)

    Bitter panicum (Hatteras)                   1                     75
                                               7                     80
                                              14                     80

    Bitter panicum (Ocracoke)                   5                     75
                                              11                     75
                                              16                     75

    Hatteras beachgrass                         4                     80
                                              12                     70
                                              13                     60

    Bitter panicum (Hatteras) plus              2                     80
    Sea oats (Duck)                             9                     75
                                              17                     75

    Bitter panicum (Hatteras) plus              3                     80
    Hatteras beachgrass                         8                     80
                                              15                     80

    Bitter panicum (Hatteras) plus              6                     75
    Sea oats (Duck) plus                       10                      70
    Hatteras beachgrass                        18                      55

    1.  Percentage of ground surface covered by shade as determined by
        projecting area covered by vegetation groundward, based on five
        1-square-meter sample subplots in each replicate (plot) per
        treatment, n = 90.

                                        24

    Table 6.  Mean aboveground biomassl for five plant species at Duck,
              North Carolina, 1974.

         Treatment                     Plot    Mean aboveground dry wt (g/m2)
                                       No.     A       p3     p4      T     U

    Bitter panicum (Hatteras)            1              67             113
                                        7              17
                                        14              46
                                        x7             43

    Bitter panicum (Ocracoke)            5       1      72      2       37
                                       11              45
                                       16              58     6
                                        x7             58

    Hatteras beachgrass                  4      10        9             96    3
                                       12      1              5              1
                                       137 3                  3
                                        x               3

    Bitter panicum (Hatteras) plus       2      26        6            102   25
    Sea oats (Duck)                      9               85
                                       17              91    94
                                        x              61

    Bitter panicum (Hatteras) plus       3      15      35             149
    Hatteras beachgrass                   8      5       15
                                       15 7            55    25
                                        x              35

    Bitter panicum (Hatteras) plus       6               23             74
    Sea oats (Duck) plus                10       5        6                   1
    Hatteras beachgrass                 18                7 7                 1
                                        x              12

    1.  Based on five 1-square-meter sample subplots in each replicate
        (plot) per treatment, n = 90.

    2.  Ammophila brevitigutata (American beachgrass).

    3. Panicuwn amarum (bitter panicum).

    4.  Panicmn amarulum (shoredune panicum).

    5.  Triplasis purpurea (purple sandgrass); sampled in only one replicate
        (plots 1 to 6).

    6.  Vnioa panicutata (sea oats).

    7. Treatment means for bitter panicum only, standard error of the
        difference among equally replicated treatment means,  s-  = 21;
        lsd      =47.                                              d
           0.05

                                      25

    fence where sand accumulation had buried the transplants about 45
    centimeters deep (Fig. 10). Dahl, et al. (1975) noted that survival
    of transplants buried by 15 centimeters or more of sand was less than
    the upright transplants. Growth and vigor of the surviving plants at
    Drum Inlet continued to be good through the remainder of the growing
    season (Fig. 11).

         The number of leaves, culms, and the cover in the October sample,
    was equal to or greater for American beachgrass and sea oats than for
    bitter panicum in all plots with treatments of two and three species
    (Tables 7, 8, and 9). All three selections of American beachgrass
    (NJ-327, Cape, and Hatteras beachgrass) produced greater values for
    number of leaves, culms, and the cover than the Hatteras selection of
    bitter panicum in single species treatments. The relatively large
    values for sea oats were partly due to a row of this species running
    through all plots. There were also scattered clumps of native
    saltmeadow cordgrass and sea oats in the experimental area.

         b.  1974.  Growth of bitter panicum and sea oats was healthier
    and more vigorous during the 1974 growing season. The increased amount
    of sand trapped and cover established from 1973 to 1974 was readily
    apparent (Figs. 12 and 13).

         In the October sample, frequency values of 50 percent and above
    were obtained for the originally planted species (Table 10), except for
    sea oats in the three-way mixture (Hatteras beachgrass plus bitter
    panicum plus sea oats) (Fig. 14). Bitter panicum had spread into all
    six American beachgrass experimental plots, but was more prevalent on
    the oceanside of the dune.   American beachgrass was not found in the
    bitter panicum experimental plots 4 and 8, and plot 6 of the bitter
    panicum plus sea oats treatment. Annuals, CakilZe edentuZa (Bigelow)
    Hooker (sea rocket) and seaside spurge, invaded some of the
    experimental plots (Table 10). Except for plots 10, 12, and 14,
    cover values were higher on the oceanside than on the sound side of
    the dune (Table 11). This condition was largely due to burial of
    first-year transplants on the sound side of the dune sections by
    about 45 centimeters of sand.  In general, cover values were somewhat
    higher in the plots with bitter panicum than in the three American
    beachgrass treatments.

         Although a few plants invaded the experimental planting, the three
    originally planted species (American beachgrass, bitter panicum, and
    sea oats) still constituted 99.5 percent of the aboveground biomass
    after two growing seasons (Table 12). Bitter panicum provided more cover
    per unit biomass than American beachgrass. This condition is well
    illustrated by comparing oceanside of the dune bitter panicum plots
    4 and 8 (Fig. 13) with oceanside of the dune American beachgrass plots
    3 and 13 (Fig. 15). All of these plots had frequencies of 100 percent,
    but the bitter panicum plots had higher cover values (Table 11) and
    the American beachgrass plots had higher biomass values (Table 12).

                                      26

    Figure 10. Sand accumulation on the
                sound side of 0.61-meter
                fence at Drum Inlet planting
                 site, May 1973

    Figure 11. Experimental planting of
               American beachgrass, bitter
               panicum, and sea oats at Drum
                Inlet, September 1973.

                      27

    Table 7.  Mean number of leaves per transect for four dune grassesl at
              Drum Inlet, North Carolina, 1973.

              Treatment                Plot             Mean No. leaves
                                        No.          per 14-m transect
                                                  A2       P3    S4       U5

    NJ-327 American beachgrass            1      104.33    0.33  2.11    4.33
                                        12     201.67    2.78  3.78   14.33

    Cape American beachgrass              2      105.00           4.56
                                        14     158.11           5.56    3.56

    Hatteras beachgrass                    3     162.00                    4.67
                                        13     167.89    1.44  6.89   15.89

    Bitter panicum (Hatteras)             4               69.78  0.56    4.33
                                         8               37.78          15.22

    Hatteras beachgrass plus              5       78.11   17.22            7.89
    Bitter panicum (Hatteras)            11       81.89   32.00           59.11

    Bitter panicum (Hatteras) plus        6        1.56   19.22          66.33
    Sea oats (Drum Inlet)                10        5.33   32.44  8.44   61.33

    Hatteras beachgrass plus              7       29.22    9.44  3.33   19.11
    Bitter panicum (Hatteras) plus        9       35.78    9.89           41.67
    Sea oats (Drum Inlet)

    1.  Based on nine transects per plot per treatment, n = 126.
    2.  AmmnophilZa brevilZiguZata (American beachgrass).
    3. Panicum amarum (bitter panicum).
    4. Spartina patens (saltmeadow cordgrass).
    5. UnioZa panicuZata (sea oats).

                                       28

    Table 8.  Mean number of culms per transect for four dune grasses  at
              Drum Inlet, North Carolina, 1973.

              Treatment               Plot            Mean No. culms
                                       No.          per 14-m transect

                                                A      P         S4     U5

    NJ-327 American beachgrass           1     27.56   0.22       0.09   1.33
                                       12     61.89   0.78      1.11   2.78

    Cape American beachgrass             2     31.22              1.67
                                       14     42.00             2.67   1.33

    Hatteras beachgrass                  3     37.00                     0.89
                                       13     36.22   0.44      2.00   3.44

    Bitter panicum (Hatteras)            4             15.89     0.22   1.11
                                        8            11.56              4.89

    Hatteras beachgrass plus             5     17.78   5.00              1.89
    Bitter panicum (Hatteras)           11     23.89   8.56             13.67

    Bitter panicum (Hatteras) plus       6      0.44   4.22             18.44
    Sea oats (Drum Inlet)               10      1.22   8.67       3.89  16.11

    Hatteras beachgrass plus             7     10.22   3.00       1.67   5.78
    Bitter panicum (Hatteras) plus       9      8.00   3.11              9.89
    Sea oats (Drum Inlet)

    1.  Based on nine transects per plot per treatment, n = 126.
    2. AmmophiZla breviZiguZata (American beachgrass).
    3.  Panicum amarum (bitter panicum).
    4.  Spartina patens (saltmeadow cordgrass).
    5.  Uniola panicuZata (sea oats).

                                       29

    Table 9.  Mean cover per transect for four dune grasses  at Drum
              Inlet, North Carolina, 1973.

              Treatment                Plot             Mean cover
                                        No.      per transect (percent)

                                                A2     P3         S4    U5

    NJ-327 American beachgrass            1     2.18   0.02       0.03  0.05
                                        12     4.01   0.04       0.05  0.26

    Cape American beachgrass              2     2.51              0.03
                                        14     3.55              0.06  0.10

    Hatteras beachgrass                   3     2.63                    0.16
                                        13     2.61   0.07       0.07  0.30

    Bitter panicum (Hatteras)             4            1.74      <0.01  0.02
                                         8            1.30             0.37

    Hatteras beachgrass plus              5     1.39   0.60             0.14
    Bitter panicum (Hatteras)            11     1.19   1.16             1.17

    Bitter panicum (Hatteras) plus        6     0.03   0.73             1.40
    Sea oats (Drum Inlet)                10     0.14   1.30       0.08  1.30

    Hatteras beachgrass plus              7     0.76   0.32       0.04  0.48
    Bitter panicum (Hatteras) plus       9      0.81   0.38             0.81
    Sea oats (Drum Inlet)

    1.  Based on nine transects per plot per treatment, n = 126.
    2.  AmmophiZa breviZiguZata (American beachgrass).
    3.  Panicum amarum (bitter panicum).
    4. Spartina patens (saltmeadow cordgrass).
    5.  UnioZa paniculata (sea oats).

                                       30

    Figure 12. Bitter panicum treatment in
                experimental planting at Drum
                Inlet, September 1973.

    Figure 13. Bitter panicum treatment in
               experimental planting at Drum
                Inlet, October 1974.

                      31

    Table 10.  Frequencyl for six dune plants at Drum Inlet, North Carolina, 1974.

                 Treatment                   Plot      Oceanside                  Frequency (percent)
                                             No.      or sound
                                                        side of         2                              6      7
                                                         dune          A      C3      E4      p5      S6     U

    NJ-327 American beachgrass                 1          ocean        100                     62
                                                         sound        100
                                              12         ocean         75                      62      12     12
                                                         sound         88             12      25             25
    Cape American beacligrass                  2          ocean         88             12      38      12
                                                         sound       100
                                              14         ocean         100             12      12      12
                                                         sound        100     12      38              12
    Hatteras beachgrass                        3          ocean        100                     50
                                                         sound        100            25
                                              13         ocean        100                      62
                                                         sound       100                      12
    Bitter panicum (Hatteras)                  4          ocean                               100
                                                         sound                        12      50
                                               8         ocean                         12     100             25
                                                         sound                                88
    Hatteras beachgrass plus                   5          ocean        100                     88              12
    Bitter panicum (Hatteras)                             sound        100             12      62
                                              11         ocean         88              12     100             25
                                                         sound         75     12      50      88             38
    Bitter panicum (Hatteras) plus             6          ocean                        12      88            100
    Sea oats (Drum Inlet)                                 sound                                50             88
                                              10         ocean          12                    100            100
                                                         sound         25     12             100             75
    Hatteras beachgrass plus                   7          ocean         50             12      7S             75
    Bitter panicum (Hatteras) plus                        sound         75             12      75             75
    Sea oats (Drum Inlet)                      9          ocean         50                      88     12     75
                                                         sound         88                     75             12

    1. The percentage of sample plots in which a species occurred, based on eight 1-square-meter sample
        subplots on oceanside and eight on sound side of dune per plot per treatment, n = 224.
    2. AmnophiZa breviligulata (American beachgrass).
    3. Cakie edentuta (sea rocket).
    4. Euphorbia polygonifotia (seaside spurge).
    5. Panicum amarwn (bitter panicum).
    6.  Spartina patens (saltmeadow cordgrass).
    7. UnioZa panicuZata (sea oats).

                                                       32

    Figure 14o Experimental planting of American beachgrass, bitter panicum,
                and sea oats at Drum Inlet, North Carolina, October 1974.

                                      33

                                    1
    Table 11.  Mean estimated cover  for all plant species at Drum Inlet,
               North Carolina, 1974.

              Treatment                Plot    Oceanside    Mean estimated
                                        No.     or sound          cover
                                                side of         (percent)
                                                  dune

    NJ-327 American beachgrass            1       ocean             16
                                                 sound             8
                                        12       ocean             21
                                                 sound            22
    Cape American beachgrass              2       ocean             16
                                                 sound              8
                                        14       ocean             12
                                                 sound            21
    Hatteras beachgrass                   3       ocean             24
                                                 sound            18
                                        13       ocean             20
                                                 sound            14
    Bitter panicum (Hatteras)            4        ocean             33
                                                 sound             13
                                         8.      ocean             46
                                                 sound             16
    Hatteras beachgrass plus              5       ocean             18
    Bitter panicum (Hatteras)                     sound             16
                                        11       ocean             33
                                                 sound             29
    Bitter panicum (Hatteras) plus       6        ocean             36
    Sea oats (Drum Inlet)                         sound             33
                                        10       ocean             26
                                                 sound             41
    Hatteras beachgrass plus              7       ocean             17
    Bitter panicum (Hatteras) plus                sound             16
    Sea oats (Drum Inlet)                 9       ocean             30
                                                 sound             11

    1.  Percentage of ground surface covered by shade as determined by
        projecting area covered by vegetation groundward, based on eight
        1-square-meter sample subplots on oceanside and eight on sound side
        of dune per plot per treatment, n = 224.

                                       34

    Table 12.  Mean aboveground biomassl for five dune plants at Drum Inlet, North Carolina, 1974.

            Treatment                   Plot            Oceanside                   Mean aboveground dry
                                         No.           or sound                        weight (g/m2)
                                                        side of
                                                         dune                A2     E3      p4     S5     U6

    NJ-327 American beachgrass             1              ocean              162            23
                                                         sound               73                    4
                                         12             ocean              120             50             25
                                                         sound              223     3      25             13
    Cape American beachgrass               2              ocean              120            43
                                                         sound              110
                                         14             ocean              214             12      3
                                                         sound              345     1       6
    Hatteras beachgrass                    3              ocean              268              6
                                                         sound              174
                                         13             ocean               225            35      2       1
                                                         sound              234
    Bitter panicum (Hatteras)              4              ocean                            142
                                                         sound                             49
                                          8             ocean                             157             14
                                                         sound                             58
    Hatteras beachgrass plus               5              ocean              142            45              3
    Bitter panicum (Hatteras)                             sound              100            57
                                         11             ocean               87            117             34
                                                         sound               84            58             48

    Bitter panicum (Hatteras) plus         6             ocean                              90            116
    Sea oats (Drum Inlet)                                 sound                             68            119
                                         10             ocean                              86             60
                                                         sound               16           200             34

    Hatteras beachgrass plus               7              ocean               99     1      29            143
    Bitter panicum (Hatteras) plus                       sound                24            82              6
    Sea oats (Drum Inlet)                  9              ocean              116            82    10       22
                                                         sound               46            33              1

    1.  Based on eight 1-square-meter sample subplots on oceanside and eight on sound side of dune per
        plot per treatment, n = 224.

    2.  AmnophiZa breviZiguZata (American beachgrass).
    3.  Euphorbia poZygonifolia (seaside spurge).
    4.  Pcmianur amarn  (bitter panicum).
    5.  Spartina patens (saltmeadow cordgrass).
    6.  Uniola panicuZata (sea oats).

                                                      35

                      .1~~~~~ /

    Figure 15o Hatteras beachgrass treatment in experimental planting at
               Drum Inlet, North Carolina, October 1974o

                                    36

         c.  Sand Accumulation..  Volumes of sand accumulated :during the
    initial 3 months (Table 13) were largely due to sand accumulation by the
    0.61-meter fence (Fig. 10), not the planted vegetation. After 3 months,
    the bitter panicum plots had as much or more sand than the other
    experimental plots except the American beachgrass plots 1 and 2 (NJ-327
    and Cape, respectively). These values had no uniform correlation with
    the 15- and 27-month values. For example, plots 1, 2, 4, and 6 had
    higher values after 3 months than the other replicate plots (12, 14, 8,
    and 10) in the respective treatments, but lower values after 27
    months (Table 13).  These results indicate that the. sand fence'did
    not significantly influence the 15- and 27-month values which were
    primarily due to the differential sand-trapping potentials of the
    vegetation.

         After 27 months, the three American beachgrass treatments had
    trapped more sand than all other treatments, and over twice as much
    as the bitter panicum treatment (Table 13, Fig. 16). The Hatteras
    beachgrass treatment accumulated slightly more sand over the 24-month
    period, June 1973 to June'1975, than the other two American beachgrass
    treatments. Over this same period, the bitter panicum treatment
    averaged about l:cubic meter of sand accumulation per linear meter of dune
    which is about one-fifth as much sand as any other treatment. Even if the
    best replicate of the bitter panicum treatment is considered, sand accumu-
    lation during this period was only-l.9 cubic meters per linear meter or
    one-third the sand accumulated by other treatments.

         All three mixed species treatments accumulated over 5 cubic meters
    of sand per meter of dune over the 24-month period.  Although the
    bitter panicum plus sea oats treatment accumulated more sand'than the
    other two mixed species treatments, American beachgrass or sea oats
    planted with bitter panicum accumulated more sand than did bitter
    panicum alone.

         Three treatments (Hatteras beachgrass, bitter panicum plus sea oats,
    and Hatteras beachgrass plus bitter panicum plus sea& oats) trapped over
    1 cubic meter of sand per meter of dune more in June 1973 to June 1974,
    than in June 1974 to June 1975. Only the NJ-327 American beachgrass
    treatment accumulated more than one-half meter of sand per meter of
    dune during the second 12-month period. If the supply of moving sand
    was equal over both years, the vegetation should have caught more sand
    during the second year since the vegetation was more dense at that time.

         Cross-section profiles indicate that the dune crest in all
    treatments moved seaward about 3 meters from June 1973 to June
    1975 (Fig. 16). The dune crest in the Hatteras beachgrass treatment
    moved the most, about 5 meters. We have observed other experimental
    American beachgrass dunes move seaward more rapidly than those
    of sea oats. This movement is due partially to American beachgrass'
    tremendous vegetative growth (by rhizomes) potential under conditions

                                      37

    Table 13.  Cumulative mean volume of sand1 accumulated over 3-, 15-, and
               27-month periods at Drum Inlet, North Carolina.

              Treatment               Plot    Volume of sand (cubic meters
                                       No.     per meter of dune) by time
                                                      after planting2
                                              3 months   15 months   27 months

    NJ-327 American beachgrass           1        3.4         4.8          7.1
                                        12       2.4         7.1         10.8
                                        -3
                                        x       2.9         6.0          9.0
    Cape American beachgrass             2        4.0         6.7          8.8
                                        14       2.7         6.6         10.3
                                        -3
                                        x       3.3         6.6          9.5
    Hatteras beachgrass                  3        2.7         6.9         10.7
                                        13       2.3         6.8          9.8
                                        x       2.5         6.9         10.2
    Bitter panicum (Hatteras)            4        3.3         3.0          3.7
                                        8       3.1         4.9          5.0
                                        x       3.2         4.0          4.3
    Hatteras beachgrass plus             5        2.3         4.8          7.3
    Bitter panicum (Hatteras)           113       2.6         5.4          8.4
                                        x       2.4         5.1          7.9
    Bitter panicum (Hatteras) plus       6        3.3         5.6          7.7
    Sea oats (Drum Inlet)               103       1.7         6.7          9.7
                                        x       2.5         6.2          8.7
    Hatteras beachgrass plus             7        2.6         6.3          7.2
    Bitter panicum (Hatteras) plus       9        2.8         6.4          9.2
    Sea oats (Drum Inlet)                x        2.7         6.4          8.2

    1.  Based on two elevational cross sections for each of two replicates
        per treatment.
    2.  Planting established in March 1973.
    3. Treatment mean.

                                       38

           NJ - 327 American beachgrass

       i-i    Planting width
        'I6. 4     12.  I16.    '23.  NA .  k '.  W.    W .  11.  h
               Cape  American  beachgrass

       9.     ..e   C32.  19.  N20.  '2.  N21.   V2   . '6   H.  e.
                  Hatteras beachgrass

           a ~ ~~~~~~~~~~~~~~~~~~~~~. *.M----

                      Bitter panicum            S13 -

         9.6 era bU.Se    p i.;    . u. biter  he.ne.cu.  he

        Hatteras beachgrass   plus bitter p anicumnpu  o~f

                '16 S.         W  ~ .  130.    14.  1.  '.   H.

    F~~~~itter 16pManicun cross sectioats

             inamteras aboecgru  mlsbteraniupw sea ot
                         level (Sa  Oforsee
                         treatments~~~$2    at ru
                         I~~nle. 17 o 95

        U.~~3

    of sand accumulation. Based on the 1975 profiles, oceanside and
    sound side dune slopes were most gentle in the American beachgrass
    treatments; the sound side slope was steeper in the other treatments,
    all of which included bitter panicum. Dune side slopes were steepest
    in the Hatteras beachgrass plus bitter panicum plus sea oats treatment.

                        IV. SUMMARY AND CONCLUSIONS

         Single culm transplants of bitter panicum can be planted in an
    inland nursery, and with routine cultivation and fertilization, can
    yield a supply of transplants for field planting at the end of the
    first growing season. A tenfold increase in number of culms was
    obtained at the end of the first growing season at Clayton, with an
    additional 2.5-fold increase by the end of the second growing season.
    The plants should be separated into single culm transplants after
    digging, dipped in a clay slurry, and packaged in reinforced paper to
    prevent desiccation. About 2 man-hours are required to dig and process
    1,000 transplants for field planting. This is about twice the time
    required to process an equal amount of American beachgrass transplants.

         Bitter panicum has the potential to stabilize foredunes and inland
    sandy areas. On the high sandy site at Duck, bitter panicum
    contributed more toward stabilizing the site than American beachgrass
    or sea oats. However, the American beachgrass planting stock may not
    have been as vigorous as generally encountered. Although bitter panicum
    can stabilize an area where relatively little sand is moving, such as
    the Duck site, the species was more vigorous and spread more at the
    foredune site at Drum Inlet where moderate amounts of sand were
    accumulating.

         Production of new shoots by bitter panicum plants buried in a 15-
    centimeter furrow was higher than transplants planted in the conventional
    upright manner at Duck. However, most of the buried transplants at
    Drum Inlet were covered by 45 centimeters of sand and unable to grow.
    Transplants should be planted in the conventional manner in areas
    accumulating sand, but may be buried in a furrow in nursery plantings
    and in areas not accumulating much sand. Recent observations suggest
    that a furrow planting technique which allows the tip end of the
    transplant to protrude above the sand, may be as good as upright
    planting, even in areas accumulating sand.

         On the foredune planting site at Drum Inlet, each of three
    selections of American beachgrass accumulated over five times more
    sand than bitter panicum in a 24-month period. Sand accumulations in
    mixed species plantings of bitter panicum with American beachgrass
    and sea oats over this period of time were more comparable with that
    of American beachgrass alone. Both American beachgrass and sea oats
    were more efficient sand trappers than bitter panicum.

                                     40

         Cross section profiles indicated that American beachgrass dunes
    moved seaward more rapidly and had more gentle side slopes than
    bitter panicum dunes. These findings and other observations suggest
    that American beachgrass dunes can repair themselves more rapidly
    following storm attack than dunes with bitter panicum or sea oats.

         The length of the growing season, and the width and number of
    leaves per unit area may be factors related to differential sand
    accumulation by the three dune grasses tested. The leaves of bitter
    panicum are wider and generally fewer per unit area than those of
    either American beachgrass or sea oats. Therefore, bitter panicum
    may not be as effective at trapping sand. The relatively short (May
    to October) growing season of bitter panicum compared to the
    relatively long one (February to November) for American beachgrass
    at this latitude may be one of the reasons for not accumulating as
    much sand as American beachgrass. The growing season of sea oats
    coincides closely with that of bitter panicum; other factors, such
    as leaf width and density, may be responsible for the differential-
    sand trapping between the two species. Since bitter panicum has a
    longer growing season at a more southerly latitude, it is probably
    a better dune builder farther south.

         Sand accumulation and dune profile data suggest that bitter
    panicum should not be used in monospecific plantings to build dunes
    along the North Carolina coast. The results indicate that the mixed
    species planting is almost as good at dune building as monospecific
    stands of American beachgrass. These mixed species plantings are
    ecologically more desirable because of the insect, disease, and
    physiological problems associated with American beachgrass at this
    latitude, In a mixed species planting of American beachgrass, bitter
    panicum, and sea oats, a dune can be built primarily by the sand
    trapping potentials of American beachgrass and sea oats; when American
    beachgrass begins dying out, it can rapidly be replaced by the other
    two native grasses to stabilize the area. The principal values of
    bitter panicum are in stabilizing sandy coastal areas and in mixed
    species plantings to build and stabilize coastal dunes in the
    southeastern United States.

                                    41

                                 LITERATURE CITED

    CAMPBELL, W.V., and FUZY, E.A., "Survey of the Scale Insect Effect on
     American Beach Grass," Shore and Beach, Vol. 40, No. 1, Apr. 1972,
     pp. 18-19.

    DAHL, B.E., et al., "Construction and Stabilization of Coastal Foredunes
      with Vegetation; Padre Island, Texas," MP 9-75, U.S. Army, Corps of
      Engineers, Coastal Engineering Research Center, Fort Belvoir, Va.,
      Sept. 1975.

    GAFFNEY, F.B., and DUELL, R.W., "Registration of Cape American Beachgrass,"
      Crop Science, Vol. 14, No. 5, Sept.-Oct. 1974, p. 777.

    LUCAS, L.T., et al., "Marasmius Blight, a New Disease of American Beach-
      grass," Plant Disease Reporter, Vol. 55, No. 7, July 1971, pp. 582-585.

    PALMER, P.G., "A Biosystematic Study of the Panicum amarum - P. amarulum
      complex (Gramineae)," Brittonia, Vol. 27, No. 2, Apr.-June 1975,
      pp. 142-150.

    SENECA, E.D., "Germination and Seedling Response of Atlantic and Gulf
      Coasts Populations of Uniola paniculata," American Journal of Botany,
      Vol. 59, No. 3, Mar. 1972, pp. 290-296.

    WOODHOUSE, W.W., Jr., and HANES, R.E., "Dune Stabilization with Vegetation
      on the Outer Banks of North Carolina," TM-22, U.S. Army, Corps of
      Engineers, Coastal Engineering Research Center, Washington, D.C., Aug.
      1967.

    WOODHOUSE, W.W., Jr., SENECA, E.D., and COOPER, A.W., "Use of Sea Oats
      for Dune Stabilization in the Southeast," Shore and Beach, Vol. 36,
      No. 2, Oct. 1968, pp. 15-21.

                                       42

                        PREVIOUS PUBLICATIONS PUBLISHED
                                      By    J
                   THE CENTER FOR MARINE AND COASTAL STUDIES

    Wave-Current Force Spectra, C. C. Tung and N. E. Huang, Report No. 72-2,
         December, 1972.

    A Survey of North Carolina Beach Erosion by Air Photo Methods, H. E. Wahls,
         Report No. 73-1, May, 1973.

    Sediment Movement in Tubbs Inlet,'North Carolina, Robert P. Masterson, Jr.,
         Jerry L. Machemehl and Victor V. Cavaroc, Jr., Report No. 73-2,
         June, 1973.

    Influence of Current On Some Statistical Properties of Waves, C. C. Tung
         and N. E. Huang, Report No. 73-3, December, 1973.

    CTD Sensors, Specific Conductance and the Determination of Salinity,
         C. E. Knowles, Report No. 73-3, August, 1973.

    Planning for North Carolina's Coastal Inlets - An Analysis of the Present
         Process and Recommendations for the Future, William S. Tilley,
         Report No. 73-4, September, 1973.

    A Preliminary Study of Storm-Induced Beach Erosion for North Carolina,
         C. E. Knowles and Jay Langfelder and Richard McDonald, Report
         No. 73-5, October, 1973.

    A Historical Review of Some of North Carolina's Coastal Inlets, Jay
         Langfelder, Tom French, Richard McDonald and Richard Ledbetter,
         Report No. 74-1, January, 1974.

    Statistical Properties of Kinematics and Dynamics of a Random Gravity
         Wave Field, C. C. Tung, Report No. 74-2, June, 1974.

    A New Technique of Beach Erosion Control, Tom French, Jerry L. Machemehl
         and N. E. Huang, Report No. 74-3, June, 1974.

    Citizen Participation in North Carolina's Coastal Area Management Program,
         Steve Tilley, Report No. 74-4, June, 1974.

    An Experimental Study of Scour Around Marine Foundations Due to
         Oscillatory Waves and Undirectional Currents, Greg N. Abad and
         Jerry L. Machemehl, Report No. 74-5, September, 1974.

    Proceedings of A Conference on Coastal Management, Report No. 74-6,
         September, 1974.

    Statistical Properties of Fluid Motion and Fluid Force in A Random
         Wave Field, Keikhosrow Pajouhi and C. C. Tung, Report No. 75-1,
         May, 1975

    Previous Publications Published Cont'd.                               Page 2

         A Numerical Method for Solutions of Systems of Non-Linear Algebraic
              Equations , John M. Klinck and Leonard J. Pietrafesa, Report No.
             75-2, July, 1975.

         Wave-Current Interactions in Water of Variable Depths , A. M. Radwan,
             C. C. Tung and N. E. Huang, Repbrt No. 75-3, August, 1975.

         Conference Proceedings Energy From The Oceans Fact or Fantasy?
             Jerome Kohl, Report No. 76-1, UNC-SG-76-04, January, 1976.

         Lonq Waves Trapped by the Cape Fear Continental Shelf Topography:
             A Model Study of Their Propagation Characteristics and Circula-
             tion Patterns , David A. Brooks, Report No. 76-2, July, 1976.

         A Comparative Study of Three Methods of Inhibiting Scour Around A
            Vertical Circular Cylinder, David M. Rooney and Jerry L. Machemehl,
            Report No. 76-3, September, 1976.
        A Flow Study of Drum Inlet, North Carolina, Paul R. Blankinship,
             Report No. 76-4, UNC-SG-76-13 November, 1976

        Dune Stabilization with Panicum amarum Along the North Carolina Coast,
            E. D. Seneca, W. W. Woodhouse, Jr., and S. W. Broome, Report No.
            77-1, UNC-SG-77-03, February, 1977.