The influence of duration-of-inundation on development of a man-initiated Spartina alterniflora Loisel. Marsh in north carolina

J. Exp. Mar. Biol. Ecol., 1985, Vol. 94, pp. 259-268

259

Elsevier

JEM 591

THE INFLUENCE OF DURATION-OF-INUNDATION OF A MAN-INITIATED SPARTZNA

ALTERNZFLORA

ON DEVELOPMENT Loisel. MARSH IN

NORTH CAROLINA’

ERNEST D. SENECA Department of Botany, North Carolina State University. Raleigh, NC 27695, U.S.A.

STEPHEN W. BROOME

and WILLIAM W. WOODHOUSE,

JR.

Department of Soil Science, North Carolina State University, Raleigh, NC 29695, U.S.A.

(Received 15 July 1985; revision received 4 September 1985; accepted 13 September 1985) Abstract:

The relative growth responses of a man-initiated Spartina altemiflora Loisel. marsh were monitored annually in four duration-of-inundation zones (4, 7, 9, and 11 h daily) during a 4-yr period following the Ill-month establishment period, with another sampling 10 yr later. There was a general trend ofmaximum values for height, number of flowers. m - 2, basal area, and aboveground standing crop to occur in the 7-h inundation zone and for these values to decrease in the 9- and 1l-h zones at the end of the second growing season (17 months after planting). This trend was reversed from the third through the fifth growing seasons with height, number of flowers . m - 2, and aboveground standing crop significantly higher in the longest (1 l-h) inundation zone. Although other angiosperms began invading the upper elevation, lesser inundated zones during the second growing season, populations were too small to sample until the following growing season (29 months after planting), when they constituted = 40% of the aboveground standing crop in the uppermost (4-h) zone. The aboveground standing crop of the S. alterniflora-dominated 11-h inundation zone became stabilized by the third growing season, but the belowground material dry weight continued to increase in all zones through the fifth season when its rate of accumulation began to stabilize in the lowermost zones. Although the uppermost zone was dominated by Phragmites communis Trin. by the twelfth season, Spartina altemiflora dominated the other zones where it constituted more than three-fourths of the aboveground standing crop and had spread N 30 m beyond the planting toward the open water of the estuary. The number of invading species present in the ORh season decreased by > 65% in the twelfth season, but the remaining invaders generally constituted relatively more of the aboveground standing crop by the twelfth season. Over the 12 seasons the experimental S. alterniflora planting developed into a marsh with the species composition dictated by the availability of disseminules of other angiosperms under the prevailing environmental conditions of duration-of-inundation and salinity. Key words: inundation; man-initiated; marsh; Spartina altemifora; North Carolina

The influence of elevation on duration-of-inundation and drainage of marsh vegetation has been well-recognized by ecologists (Chapman, 1938; Penfound & Hathaway, ’ Paper number 10001 ofthe Journal Series ofthe North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. 0022-0981851503.30 0 19x5 Elscvrer

Science Publishers B.V. (Biomedical

Division)

260

ERNESTD.SENECAE7'AL.

1938; Adams, 1963; Ranwell et al., 1964; Redfield, 1972; Mendelssohn & Seneca, 1980). Duration-of-inundation may affect spatial distribution or zonation of marsh vegetation (Adams, 1963; Redfield, 1972) and also the relative vegetative vigor of populations or stands within a marsh (Mendelssohn 8z Seneca, 1980). Techniques and procedures have been developed for the establishment of Spartina altemiflora in the intertidal zone on coarse sandy dredged material and along eroding estuarine shorelines to stabilize the substratum and to initiate marsh development (Broome et al., 1974; Woodhouse et al., 1974; Garbisch et al., 1975; Seneca et al., 1976; Woodhouse et al., 1976; Woodhouse, 1979). Usually 16 to 18 months, which include two aboveground growing seasons, are required for a man-initiated marsh to stabilize the substratum material and develop vegetative cover similar to that of a natural marsh. We are unaware of studies that have monitored S. altemiflora growth and development following initiation for more than a few years, although studies spanning shorter periods are available (Woodhouse et al., 1974; Cammen, 1975; Garbisch et al., 1975; Seneca et al., 1976). The current study documents the relative growth responses of an experimental planting of S. alterniflora Loisel. in four zones of duration-ofinundation during a 4-yr period following the 17-month establishment period, with another sampling the tenth year following the establishment period. The investigation also monitored invasion of the experimental marsh by other angiosperms and temporal changes in their relative contribution to the aboveground standing crop in the four zones. MATERIALS

AND

METHODS

In early April, 1971, transplants of S. altem$ora from several populations along the North Carolina coast were planted in a randomized design on an old dredged material disposal island in the Cape Fear River estuary near Snow’s Cut (34”07’N:77”56’W). Each transplant consisted of a single stem (culm) often with small young culms at the base and a well-developed root system. Transplants were hand-planted in 15 three-row plots which were oriented perpendicular to the shoreline from 0.4 to 0.8 m above mean sea level (MSL). They were spaced 0.9 m apart in the rows which were also 0.9 m apart. Dredged material was deposited on the planting site 60 days prior to transplanting. The site had a slope of 1.5 to 2.0%, and consisted of 96% sand, 1y0 silt, and 3% clay. The salinity of interstitial water averaged z lo%,. In September of the second aboveground growing season (17 months after planting) and for three consecutive growing seasons thereafter, the planting was sampled by stratifying into four elevation zones (0.7 to 0.8, 0.6 to 0.7, 0.5 to 0.6, and 0.4 to 0.5 m MSL) which were observed to be inundated = 4, 7, 9, and 11 h daily, respectively, on an average tide. These relative duration-of-inundation times were verified by predicted values determined for known elevations based on tide table data. The 15 plots were parallel and adjacent to each other and extended over the elevation gradient. Each plot contained all four duration-of-inundation zones. Within each inundation zone in

INUNDATION

AND MARSH

DEVELOPMENT

261

each of the 15 plots, the average height of the five tallest culms, the number of flowering culms, the total number of culms, basal area, and aboveground dry weight (standing crop) were determined for a 0.2%m2 sample during each growing season. Basal area was determined by clipping the aboveground cuhns at their bases, bunching them together, and measuring the cross-sectional diameter from which basal area was calculated. The aboveground standing crop of invading species was also determined in each 0.25-m2 sample plot the third, fourth, and fiftfi growing seasons. One belowground core sample (8.5 cm in diameter and 30 cm depth) was colfected from each 0.25m2 sample area at the end of the second growing season and two were collected each of the following three growing seasons. These cores sampled the zone of maximum root concentration, as determined from preliminary samples. This belowground material consisted of culm bases, rhizomes, and roots. No attempt was made to separate live from dead material or to separate the below~ound material of different species as they invaded the planting. In early October, 1982, 10 years following the initial 17-month establishment period, the planting was sampled in the same manner as described above with the following exceptions. Aboveground material was sampled with seven 0.25-m’ plots in each zone and only one belowground core was collected from each plot. Analysis of variance was performed according to Steele & Torrie (1960) using the Statistical Analysis System (Barr et al., 1979). All statistically significant differences were determined at the 0.05 level. RESULTS

Analysis of variance of second through f#th growing season data indicated significant differences in S. altemzjlora growth among the four inundation zones based on all variables except belowground material (Table I, Fig. 1). With the exception of the number of cuhns, there was a general trend for maximum values for all variables to occur in the 7-h in~dation zone at the end of the second growing season; at this time, height, number of flowers, basal area, and aboveground standing crop were significantly greater in the 4- and 7-h inundation zones than in the 1l-h zone. Third, fourth, and fifth growing season data for all growth variables generally described a trend of increasing values from the 4- to the 1l-h inundation zone (Table I, Fig. 1). Maximal values, which were si~i~c~tly higher than those in all other zones, occurred in the 1l-h zone for height, number of Ilowers, and above~ound standing crop from the third through the fifth seasons. There were also significantly more total cuhns per unit area in this zone in the fourth and fifth seasons. For aboveground standing crop, each successively longer inundation zone produced signiticantly more biomass from the third to the fifth season. Further, the aboveground standing crop in the 1l-h inundation zone stabilized by the third growing season. The below~ound material dry weight data continued to increase in all zones through the fifth growing season (Fig. 1). Several flowering plants invaded the experimental planting the second growing

ERNEST D. SENECA ET AL.

262

TABLE I Means

and s$’ for hour measures of Spartim alterniflora growth for four duration-of-inundation second through fifth, plus the twelfth growing season following planting.

Zone (h) by season

Months after planting

Second 4 7 9 11 4

17

Third 4 I 9 11 s,

29

Fourth 4 7 9 11 s,

41

Fifth 4 7 9 11 s,

53

Twelfth 4 I 9 11 s,

zone? for

Height (cm)

No. flowering culms.m-2

142 151 136 134 4

94 101 99 88 3

251 298 320 286 5

119 128 91 15 10

93 123 144 154 5

23 21 55 19 5

194 239 238 255 14

120 125 125 106 16

106 121 145 163 5

20 29 42 87 10

122 151 176 234 19

100 94 127 134 20

123 129 140 162 6

18 22 38 60 8

106 162 181 261 26

106 125 148 139 16

_c

-=

_=

_c 121 159 159 22

137 120 127 127 10

15 13 13 5

Total no. culms .rn-a

241 207 242 47

Basal area (cm*.m-*)

a Standard error of equally replicated duration-of-inundation zones, n = 60 for second through fifth seasons, n = 21 for twelfth season. b The 4-, 7-, 9-, and 1l-h duration-of-inundation zones were 0.7-0.8, 0.6-0.7, 0.5-0.6, 0.4-0.5 m MSL in elevation, respectively. c No S. alremifloru in samples; a number of invading species were present.

season but populations were too few to sample for biomass until the third and subsequent growing seasons (Table II, Fig. 1). The invaders were mostly characteristic of brackish and freshwater marshes but some were common upland weeds (Table II). Through the fifth season, Aster subulatus, A. tenuifolius, Scirpus americanus, S. robustus, and S. validus constituted the highest proportions of aboveground dry weight of

INUNDATION

AND MARSH

DEVELOPMENT

263

invading species, except for Phragmites communis in the 4-h zone in the fifth season (Table III). Scirpus americanus, S. robustus, Aster subulatus, and A. tenuifolius were the only invaders sampled in the 1l-h zone through the fifth season where they constituted < 2% of the sample weight each season.

5000

0 I

4500

n

I

ABOVEGROUND,~.oltrrnifloro ABOVEGROUND.INVADING SPECIES BELOWGROUND,ALL SPECIES

4000

% 3000 s s=2500 0

”

234512

234512

234512

234512

Fig. 1. September aboveground and belowground standing crops + SE bars for Spartina alterniflora and invading species for second through fifth plus twelfth growing seasons following planting for each of four duration-of-inundation zones: means and SE for invading species in 1 l-h inundation zone by season: 3rd=4~3,4th=12~8,5th=15~7,and12th=35~26g~m-*; the 4-, 7-, 9-, and 1 l-h duration-ofinundation zones were 0.7-0.8, 0.6-0.7, 0.5-0.6, and 0.4-0.5 m MSL in elevation, respectively.

The proportion of total aboveground dry weight contributed by invading species was highest (41%) in the 4-h inundation zone in the third growing season and it remained relatively constant in this zone through the fifth season (Table III, Fig. 1). During the fourth growing season it was highest and about equal in the 4- and 7-h inundation zones, where it constituted 44 and 43%, respectively of the standing crop. There was limited invasion, primarily by Scipus validus, in the 9-h zone at that time. The 4-h zone still had the highest proportion of total aboveground dry weight contributed by invading

264

ERNEST

D. SENECA

ET AL.

species (42%) in the fifth season, but there were decreases in both the 7- and 9-h zones. The proportion of total aboveground dry weight contributed by the invading species decreased as the duration-of-inundation increased every season except for the 9-h zone TABLE II Presence of flowering plants which invaded the Sparcitzaaltemz~oru planting during the second through the fifth, plus twelfth growing season following planting. Growing season Scientific name

2

3

4

Aeschynomene indica L. Altemanthera philoxeroides (Mart.) Griseb. Amaranthus cannabinus (L.) J. D. Sauer Aster subulatus Michx. Aster renuifolius L. Atrzplex patula L. Bomkhia fmtescens (L.) DC. Cypencs polystachyos var. texensis (Torr.) Fern. Cypems strigosus L. Daubentonia punicea (Cav.) DC. Echinochloa walteri (Pursh) Heller Erianthus gikanteus (Walt.) Muhl. Fimbristylis spadicea (L.) Vahl. Iva fmtescens L. Juncus roemerianus Scheele Panicum dichotomifomm Michx. Panicum virgatum L. Phragmites communis Trin. Pluchea purpurascens (SW.) DC. Polygonum pensylvanicum L. Sabatia stellaris Pursh Scirpus americanus Pers. Scirpus robustus Pursh Scirpus validus Vahl. Spartina cynosuroides (L.) Roth. Spartina patens (Alt.) Muhl. Suaeda linearis (HI.) Moq. Vigna luteola (Jacq.) Benth.

X X X X

X X X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X X

in the twelfth season. The reverse was true for Spartina altemiflora which contributed nearly 100 and 58% of the total aboveground dry weight in the ll- and 4-h zones, respectively, through the fifth season. The total aboveground standing crop for S. altemiflora plus invading species increased as the duration-of-inundation increased each season after the second with a maximal crop of 13 13 g * m - 2 in the S. alternljlora -dominated 11-h zone after the fifth season (Fig. 1). Although belowground standing crop decreased as the duration-of-inundation increased during the second growing season, this trend was reversed generally from the

INUNDATION

265

AND MARSH DEVELOPMENT

third to the ftith growing seasons (Fig. 1). It remained relatively constant (1534 to 1565 g. m - 2, in the 4-h zone until the fifth season when it increased by > 800 g. m - *. This increase coincided with the invasion of P~rugm~tes commu~is, which contributed significant belowground material, primarily in the form of its relatively large, prolific rhizomes. The total aboveground and belowground dry weight for all species was highest in the 9- and 1 l-h inundation zones and significantly lower in the 4-h zone in the fifth growing season {Fig. 1). TABLE III Percentage of aboveground dry weight produced by Spnrtino altemiflora and invading species in four duration-of-inundation zonesa for second through liRh, plus twelfth growing season following planting: tr, trace amount, < 0.5 %. % dry weight produced by inundation zone (h) by season Species

4

I

3

4

5

12

3

4

19 65 00 0 0

3

1 0 104

3

1 7

0 0

0 0

tr

1

Aster subulatus A. tenusfolius funcuf roemerianus Phra~ites communis Plucheu purpurascens Scirpus americanus S. robustus S. validus Spartina alternijlora S. cynosuroides

0 0 1 6 563034 1 17 59 56 000400

Other speciesi’

10

I

0700 90 2 0 14 0

11

1 30

8 58

0 0

88

57

2

0

tr

tr

a The 4-, 7-, 9-, and 1l-h duration-of-inundation in elevation, respectively. b Listed in Table II.

9 5

12

tr tr 10 0 Otr

3

4

tr tr 1 4 00

11 5

12

3

4

5

12

0 4 00

0 3

0 tr 0

1 tr 0

1 tr 0

0 0 0

010000

tr

5000 1 4 7 tr 76 0

0000

00000

87 8

0000 0

0

4

tr

tr

tr 0

0 3

6 3 87 79 012

0 100 0

0 99 0

0 99 0

2 96 0

20

3

2

427 92 68 0 0

tr

000000

zones were 0.7-0.8,0.6-0.7,0.5-0.6,

0000 and 0.4-0.5 m MSL

By the twelfth growing season, the 4-h inundation zone was dominated by P. cornrnu~~ with some Spartina c~~o~ro~e~, but no S. u~te~z~or~ (Table 1X1,Fig. 1). The aboveground standing crop at this time was almost twice that at the end of the fifth growing season in this zone (Fig. 1). The twelfth season’s total aboveground standing crop in the 7-h inundation zone was about equal to, and those in the 9- and 11-h inundation zones significantly less than, corresponding values in these zones in the f&th growing season. In each of these zones, 5’. ultem~~oru constituted more than threefourths of the aboveground standing crop after 12 seasons. Belowground standing crop also decreased in the 1l-h inundation zone from the fifth to the twelfth season (Fig. 1). Although S. alternzfloraconstituted 96% of the aboveground standing crop in this zone in the twelfth season, there was a significant decrease in its standing crop after the fifth season and invading species were relatively infrequent, It is ~teres~ng that of the 21 invading species recorded in the fourth and fifth growing seasons, only 6 were observed in the twelfth season.

166

ERNESTD. SENECAETAL. DISCUSSION

Growth variables for S. altemiflora were generally higher in the 4- and 7-h durationof-inundation zones than in the 11-h zone after the second growing season. This condition was reversed from the third through the fifth seasons as growth of S. altemiflora increased with increasing duration-of-inundation. Through the first 17 months, S. altemiflora experienced little interspecific competition as it exploited the unoccupied substratum resource and achieved nearly complete vegetative cover. Although present in only limited numbers during this establishment period, invading angiosperms became relatively numerous in the shorter periods of inundation during the third growing season. Reduced aboveground standing crop for S. aitemifIora in the 4- and 7-h zones at this time may have been due to competition with these invading plants. The decline in aboveground standing crop of S. altemiflora in these zones was not compensated for by the production of the invading species until sometime after the fifth, but not later than the twelfth season. Invasion of the upper parts of the marsh by other plants was possible because of available seed sources already on the dredged material disposal island and the invading species’ tolerance to relatively low substratum salinity (X lo%,) and relatively short periods of inundation. S. altemifIora was able to maintain dominance in the lower two zones apparently because few invading plants could tolerate the longer period of tidal inundation. Total aboveground and belowground standing crop for all species after the fifth growing season was highest in the 9- and 1l-h inundation zones where S. altern$ora appeared best adapted to out-compete other species. Although we have no data on sedimentation rate, observations at this site since the fifth growing season indicated sediment accretion. By the twelfth season, the 11-h inundation zone was no longer inundated for this length of time. The original planting contained a zone (1 1 + ) which was lower in elevation and was inundated longer than 11 h daily. By the twelfth season, this lower zone was more comparable to the 1l-h zone and we sampled it in a similar manner. This 11+ zone was completely dominated by S. altemifora with no invading species and contained 806 f 88 and 2946 f 211 g ’ m - 2 aboveground and belowground standing crops, respectively. When compared to the value of belowground standing crop (2843 g. m - 2, for the fifth season in the 1l-h zone, the twelfth season value for this variable in the 11 + zone suggests that the rate of belowground material accumulation has stabilized. With sediment accretion, vegetation from the original planting has spread 30 m toward the open water of the estuary such that the marsh has expanded greatly. At the higher elevations, invading native marsh species now dominate whereas at the lower elevations with sediment accretion, S. altemifora is spreading and maintaining dominance down to about mean sea level. It is important for management personnel to realize that planting of an unvegetated intertidal area along the Atlantic coast of the United States with S. aZtemz$oradoes not in itself guarantee an S. altemifora-dominated marsh several years hence, even if the initial planting is successfully established. Assuming successful establishment, other

INUNDATION

AND MARSH DEVELOPMENT

267

factors such as duration-of-inundation, salinity levels, and plant species composition of natural marshes in the vicinity are important considerations in predicting composition of rn~-initiated marshes three or more years after planting. In lower salinity sites of the estuary one would expect competition from numerous angiosperms tolerant of brackish water and relatively short periods of inundation. Under these conditions, S. alternifIora would probably remain dominant as a border at the lowest elevation of vegetation. Results of monitoring this experimental planting of S. aite~z~ora over a period of 12 growing seasons indicates that it was an almost pure stand through the first 17 months. From the third through the twelfth growing season, it became a mixed species marsh in the upper elevation zones and remained S. alte~z~ora-dominated at the lower elevation zones. The experimental planting developed into a marsh with the species composition dictated by the availability of disseminules of other angiosperms under the prevailing environmental conditions of duration-of-inundation and relatively low salinity. ACKNOWLEDGEMENTS

The authors wish to thank C. L. Campbell, L. L. Hobbs, and Dr. R. J. Monroe, Statistici~, N. C. State University. Research was supported by the Coastal En~nee~ng Research Center, U. S. Army Corps of Engineers Contract No. DACW 72-72-C-0012; the Univ. of North Carolina Sea Grant College Program, Office of Sea Grant, NOAA, Department of Commerce, Grant No.’ GH-103; and the North Carolina State Univ. A~cult~~ Research Service.

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Vol. 44, pp. 445-456. BARR, A.J., J.H. GOODNIGHT,J.P. SALL, W.H. BLAIR & D.M. CHILKO, 1979. SAS user’s guide. SAS Institute, Inc., P. 0. Box 10066, Raleigh, NC, 494 pp. BROOME,S. W., W. W. WOODHOUSE,JR. 62 E. D. SENECA,1974. Propagation of smooth cordgrass, Spartina ~~fer~z~ora,from seed in North Carolina. Chesapeake Sci., Vol. 15, pp. 214-221. CAMMEN,L.M., 1975. Accumulation rate and turnover time of organic carbon in a salt marsh sediment. Limnol. Oceanogr., Vol. 20, pp. 1012-1015. CHAPMAN,V. J., 1938. Studies in salt-marsh ecology. I-III. J. Ecol., Vol. 26, pp. 144-179. GARBISCH,E. W., JR., P. B. WOLLER& R. J. MCCALLUM,1975. Salt marsh establishment and development. U. S. Army Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va., Tech. Memo. No. 52, 110 pp. MENDELSSOHN,LA. & E.D. SENECA, 1980. The influence of soil drainage on the growth of salt marsh cordgrass Spartina altern#lora in North Carolina. Estuarine Coastal Mar. Sci., Vol. 11, pp.27-40. PENFOUND, W.T. & ES. HATHAWAY,1938. Plant communities in the marshlands of south-western Louisiana. Ecol. Monogr., Vol. 8, pp. l-56. RANWELL,D.S., E.C.F. BIRD, J.C.E. HUBBARS& R.E. STEBBINGS,1964. Spar&a salt marshes in Southern Engiand. V. Tidal submergence and chlorinity in Poole Ha&our. J. EC& Vol. 52, pp. 627-64 1. REDFIELD,A.C., 1972. Development of a New England salt marsh. Ecol. Monogr., Vol. 42, pp. 201-237.

268 SENECA, E.D.,

ERNEST

D. SENECA

ETAL.

S.W. BROOME, W.W. WOODHOUSE, JR., L.M. CAMMEN & J.T. LYON, III, 1976. Establishing Spartina alternijlora marsh in North Carolina. Environ. Conserv., Vol. 3, pp. 185-188. STEELE,R. G.D. & J. H. TORRIE, 1960. Principles andprocedures ofstatistics. McGraw-Hill Book Company, Inc., New York, 481 pp. WOODHOUSE,W. W., JR., 1979. Building marshes along the coasts of the continental United States. U. S. Army Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va. Spec. Rept. 4,96 pp. WOODHOUSE,W. W., JR., E. D. SENECA& S. W. BROOME,1974. Propagation of Spartina altemiflra for substrate stabilization and salt marsh development. U.S. Army Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va. Tech. Memo. 46, 115 pp. WOODHOUSE,W. W., JR., E. D. SENECAJr S. W. BROOME,1976. Propagation and use of Spartina alterniJora for shoreline erosion abatement. U. S. Army Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va. Tech. Rept. 76-2, 68 pp.