sand accretion and salinity as constraints on the establishment ofleymus arenariusfor land...

Annals of Botany 78 : 611–618, 1996

Sand Accretion and Salinity as Constraints on the Establishment of

Leymus arenarius for Land Reclamation in Iceland

S. GREIPSSON* and A. J. DAVY

School of Biological Sciences, Uni�ersity of East Anglia, Norwich, NR4 7TJ, UK

Received: 29 February 1996 Accepted: 13 May 1996

Seed harvested from wild populations of Leymus arenarius is sown extensively in Iceland to stabilize sandy barrens,on the coast and inland. Sand accretion can reach 50 cm over 3 months in summer near the outwash of glacial riverson the south coast of Iceland and thus may be an important factor influencing survival and growth of L. arenarius.

Newly germinated seedlings had great potential for elongation in darkness (etiolation). The length of the longestetiolated leaf increased significantly with seed mass. The etiolation response proved to be a good predictor of theirability to emerge from burial with sand. The mean length of etiolated shoots was approx. 16 cm and 40% of seedlingsemerged when germinating seeds were buried with 15 cm of sand, whereas none emerged from burial under 20 cm ofsand. A moderately high and sustained rate of sand deposition (2–4 cm week−"), applied to 10-week old seedlings ina glasshouse experiment, significantly increased leaf length and the allocation of biomass to shoots, such that overallbiomass was slightly but not significantly increased.

The growth responses of seedlings of one coastal population and two inland populations of Leymus arenarius werecompared when challenged with salinities ranging from 0 to 600 m NaCl in sand culture. The numbers of tillersproduced by the coastal population was stimulated by salinity in the range 200–400 m NaCl, unlike their inlandcounterparts. The total dry mass of the coastal population was less adversely affected by high salinity than that ofthe two inland populations, mainly because root biomass was reduced less ; total leaf area was also slightly lessreduced in the coastal population. The reclamation of sand barrens in Iceland with high accretion rates would benefitfrom sowing seeds from larger-seeded populations, at a depth of 5–10 cm; at coastal reclamation sites, it would bepreferable to use seed from the more salt-tolerant coastal populations. # 1996 Annals of Botany Company

Key words : Leymus arenarius, lyme grass, sand accretion, etiolation, seedling emergence, seed mass, salt tolerance,revegetation.

INTRODUCTION

Mobile sand, resulting from volcanic activity, glaciers andother erosive forces is one of the major environmentalproblems faced by Iceland (Runo! lfsson, 1987). Muchmaterial is carried to the coast by torrential glacial rivers,where it is deposited and blown back on-shore by theprevailing winds to create vast, desolate, sandy plains(Greipsson and El-Mayas, 1996). The only dune-buildinggrass suitable for stabilizing drifting sands and erodingfronts in the cold climate is Leymus arenarius (L.) Hochst.(Syn. Elymus arenarius L.) and this grass has been usedextensively, both near the coast and inland (Sigurbjo$ rnsson,1960; Greipsson and Davy, 1994a). The scale of use dictatesthat planting must be from seed rather than clonalpropagation and so eventual success in vegetative coverdepends critically on the uncertainties of seedling estab-lishment and survival in a physically unstable environment;sand levels on frontal dunes may fluctuate violently withwind or tide, and sea spray may impose salinity stress.

Burial with sand is a major hazard. Seeds can be burieddeeper than their capacity to emerge and seedlings may beunable to elongate as fast as the sand accretes. Emergence

* Present address : Soil Conservation Service of Iceland,Gunnarsholt, 851 Hella, Iceland.

from burial in sand involves both the ability to survivedarkness (Sykes and Wilson, 1990) and the potential toelongate and penetrate a thick sand layer. This will dependpartly on seed mass (Maun and Lapierre, 1986; Davy andFigueroa, 1993) but seedlings of beach plants may showplastic responses in biomass allocation in response to sandaccretion (Harris and Davy, 1987). The ability to elongatein the dark (etiolate) is likely to be an indication of thepotential of a seedling to emerge from burial.

Tolerance of salinity is also a factor relevant to es-tablishment. Leymus arenarius is primarily a coastal species(Bond, 1952) that has long been regarded as a halophyte(Benecke, 1930; Benecke and Arnold, 1931). However, inIceland, there are inland populations whose germination isless tolerant of salinity than the coastal ones (Greipsson andDavy, 1994b) and it is not known to what extent seedlingsof different populations of L. arenarius vary in their salttolerance. Beach and dune grasses typically experience saltspray but long periods of inundation in sea water are rarebecause of the rapid drainage of sands. Rozema et al. (1985)considered that airborne salt-spray rather than continuoussoil salinity limits plant growth on the beach. Exposure tosalinity, like erosion and accretion, tends to be episodic (DeJong, 1979; Barbour, DeJong and Pavlik, 1985).

Recent work has highlighted the importance of en-vironmental conditions and seed mass in determining the

0305-7364}96}11061108 $25.00}0 # 1996 Annals of Botany Company

612 Greipsson and Da�y—Sand Accretion, Salinity and Growth in Leymus arenarius

germination success of L. arenarius in restoration pro-grammes (Greipsson and Davy, 1994b, 1995). The workdescribed in this paper has focused on the next critical stageof its life-history by examining the effects of burial with sandand of salinity on seedling establishment and growth, andtheir significance for restoration. Our aims were to investi-gate (1) the ability of seedlings of L. arenarius to etiolateand effects of seed mass on their elongation; (2) their abilityto emerge from different depths of burial in sand; (3) theeffects of varying sand accretion rates on seedling growth, inrelation to accretion rates in the field; (4) the effects ofepisodes of varying salinity on the growth of seedlings ofinland and coastal populations.

MATERIALS AND METHODS

Field measurements of sand accretion

Sand accretion was measured in easily accessible Leymusdunes on the coast at Krosssandur in the south of Iceland,an area with high sand deposition rates, because of itsproximity to a glacial river. Sand deposition was assessed bydriving four galvanized iron stakes (2-m fence posts) to adepth of 50 cm in Jun. 1989 and measuring the heightprojecting above ground at intervals. Measurements weremade monthly from Jul. to Sep. 1989, and in Jul. and Sep.1990.

Effects of seed mass on seedling elongation in darkness

A batch of seeds with a wide range of mass was collectedfrom the population at Vatnsbæir in the north of Iceland inlate Aug. 1989. Plants in this area experience very high ratesof sand accretion, because a nearby glacial river supplieslarge amounts of fresh sand to the shore. Ten individualspikes were collected and air-dried, before being stored inpaper bags at room temperature. Sixty seeds (caryopses) ofvarying size were cleaned manually from the husks andweighed individually. Then they were stratified for 2 weeksat 5 °C, before being allowed to germinate on moist filterpaper in Petri dishes, in the dark under alternatingtemperatures (12 h, 10 °C}12 h, 30 °C), as prescribed byGreipsson and Davy (1994b). Each germinating seed wasplaced in a 20 cm test tube with a double layer of a wet filterpaper at the bottom. These were placed in the dark at roomtemperature for 14 d, after which time seedlings ceased toelongate. The lengths of the longest root, the longest leafand the coleoptile were recorded.

Emergence of seedlings from different depths of burial insand

Seeds from the Vatnsbæir population of average size(mean mass 12±6³0±2 mg) were selected and allowed togerminate, as described previously. The germinating seedswere subsequently placed in polythene buckets (25 cmtall¬17±5 cm diameter), on a 3-cm thick bed of washedsilica sand (Leighton Buzzard DA 21D, Hepworth Mineralsand Chemicals Ltd, UK), and covered with 5, 10, 15 or20 cm of moist sand. The sand had rounded grains (mean

size 337 µm and range 90–1000 µm) and a loose bulk densityof 1±49 kg l−" when dry. Five seeds, at equal spacing, wereplanted in each of three replicate buckets for each depth ofburial. The buckets were kept at room temperature(17–22 °C) and the sand was kept moist by careful weeklywatering. The emergence of all seedlings was recorded overa period of 30 d.

Effects of rate of sand accretion on growth of seedlings

Seeds from the Vatnsbæir population were allowed togerminate, as previously, and the seedlings were grown onfor 10 weeks in a heated glasshouse (17–22 °C) withsupplementary lighting (see below) at the University of EastAnglia, UK, in a mixture of John Innes compost no. 3 andwashed silica sand (2:1 by volume) in individual plastic pots(12±7 cm diameter¬12 cm deep). Seedlings were then trans-planted to individual vertical earthenware tubes (22 cmdiameter¬30 cm deep), without disturbing the root ball.The root ball settled to a depth of 8 cm in the wider tubesand washed silica sand was added to complete this level.

Forty plants of similar size were allocated to four sand-accretion treatments, with ten replicates for each. Threetreatments, in the earthenware tubes, comprised sandadditions of 0, 2 and 4 cm week−", respectively; the fourthtreatment consisted of plants retained in the plastic pots,without sand accretion, but without the shading effects andincreased rooting volume associated with being in the tube(control for tubes). In order to complete the highest accretionrate, 6-cm plastic collars were fitted to extend the tubeswhen necessary. The treatments were laid out in randomizedblocks on the bench of a heated glasshouse, with sup-plementary light (high pressure sodium, 310 W) adjusted togive a 16-h daylength. Tubes and pots were watered once aweek and re-randomized every 3 weeks. Plants wereharvested 50 d after the first addition of sand (i.e. after sevenincrements totalling 14 and 28 cm of silica sand respectivelyfor treatments 2 and 3). For each plant, the shoot height andleaf lengths were measured. Then roots and rhizomes werecarefully washed free of the sand and separated from theshoots ; finally, the plant fractions were dried at 80 °C for48 h before weighing. Comparisons between mean valueswere made using one-way ANOVA and subsequentlyTukey’s multiple range test.

Effect of salinity on the growth of seedlings

Seeds were collected in Aug. 1989 from one coastalpopulation at Thorla! ksho$ fn and two inland populations atKeldur and Sandvı!k, respectively. They were air-dried andstored in paper bags at room temperature until use. Theseeds were allowed to germinate as described previously,before being transferred to sand culture. Quartz sand (21grade) was sterilized by autoclaving for 20 min at 115 °C.Seedlings were planted in individual plastic plant pots(12±7 cm diameter¬12 cm deep), each lined with fibreglassfilter paper, and filled with the sand. Five replicate plantsfrom each population were subjected to four salt concen-trations (0, 200, 400 and 600 m NaCl). They were given arepeating 3-d cycle of solutions, applied to the surface of

Greipsson and Da�y—Sand Accretion, Salinity and Growth in Leymus arenarius 613

the culture, which started with 50 ml of a 0±5 strengthHoagland’s nutrient solution (Hoagland and Arnon, 1938),followed by 50 ml of distilled water and then 50 ml of theappropriate salt solution. This was designed to mimicepisodic salinity and prevent the accumulation of salts in thesand. Each pot drained freely to a plastic saucer, which wassubsequently emptied as necessary, to avoid cross-con-tamination of solutions. The surface of the sand in each potwas covered with sterilized black polythene beads to preventalgal growth. The experiment was laid out in randomizedblocks on a glasshouse bench, with supplementary light(high pressure sodium, 310 W) adjusted to give a 16-hdaylength. Pots were re-randomized every 3 weeks. Meandaily maximum}minimum temperatures in the glasshousewere 23}16, 25}16 and 26}17 °C for Feb., Mar. and Apr.1990, respectively, during the experiment. Plants wereharvested after 90 d; leaf areas were measured using a leafarea meter (Lambda Instruments Corp., Model LI-3000)and dry masses determined (80 °C for 48 h).

Responses relative to plants in the same populationtreated with 0 m NaCl were calculated and the percentagedata transformed to the arcsine square root before statisticalcomparison using one-way ANOVA and, subsequently,Tukey’s multiple range test.

RESULTS

Field measurements of sand accretion

Sand accretion at Krosssandur was rapid (Fig. 1). Totalaccretion averaged 26±1 cm between Jul. and Sep. 1989, witha maximum value of 33±5 and a minimum value of 19±2 cm.The maximum sand deposition recorded over 1 month atany post was 22±5 cm. Between Sep. 1989 and Jul. 1990 therewas no net sand deposition and erosion of 10±5 cm of sandwas recorded at one post. From Jul. to Aug. 1990, onaverage, 47±6 cm of sand was deposited. The maximum sanddeposition at any post in 1990 was 52±6 cm. Over the whole

Sep.

80

0Jul.

1989

Rel

ativ

e sa

nd

leve

l (cm

)

60

40

20

Aug. Sep. Jul. Aug.1990

F. 1. Sand deposition in Leymus arenarius dunes at Krosssandur onthe south coast of Iceland during the summers of 1989 and 1990.Changes in the sand level were measured relative to four permanent

metal stakes (D, E, *, +).

20

30

0

Len

gth

of

lon

gest

leaf

(cm

)

15

10

5

5 10 15Seed mass (mg)

20

25

F. 2. The relationship between etiolation potential, measured aslength of the longest leaf after 2 weeks in darkness, and seed mass inLeymus arenarius. Regression equation: y¯ 5±496 x!

±%#) ; r#¯ 0±42;

n¯ 60.

period from Jul. 1989 to Sep. 1990 an average of 71±4 cm ofsand deposition was found on these coastal dunes. Theplants growing under these extreme conditions of accretionwere vigorous and produced seeds in the autumns of both1989 and 1990.

Effects of seed mass on seedling elongation in darkness

Etiolated seedlings produced shoots with a mean longest-leaf length of 15±6 cm but ranging from 5±6 to 26±0 cm. Leaflength was strongly dependent on seed mass (Fig. 2),suggesting that it was limited by the resources stored in theseed. The relationship was best described by a powerfunction, which was highly significant and accounted fornearly half of the variation in leaf length (r#¯ 0±42, P!0±001). The mean length of the longest root produced was15±4 cm (range, 6±8–30±0 cm). The relationship betweenlongest root and seed again fitted a power function and wassignificant but it accounted for much less variation than thatfor its leaf counterpart (r#¯ 0±12, P! 0±01).

Emergence of seedlings from different depths of burial insand

As expected, both the percentage emergence of seedlings(Fig. 3) and their rate of emergence declined with increasingdepth of burial in sand. The first seedling from the 5 cmsand burial emerged after 5 d and 100% emergence wasobserved after 7 d. The first emergence from the 10 and15 cm burial depths were after 6 and 11 d, respectively andthe maximum emergences were reached after 12 and 15 d,respectively. No seedlings managed to emerge from a depthof burial with sand of 20 cm. Hence the effective emergence


25

100

0

Mea

n e

mer

gen

ce (

%)

50

25

10 15 20Depth of burial (cm)

75

5

F. 3. The mean percentage emergence of Leymus arenarius seedlingsafter burial at different depths with sand at germination. Vertical bars

represent³s.e., n¯ 3. Curve interpolated.

limit for newly germinated seeds of Leymus arenarius isbetween 15 and 20 cm.

Effects of rate of sand accretion on growth of seedlings

The growth responses of seedlings of L. arenarius toexperimental depositions of sand are shown in Fig. 4. Thetotal dry mass per plant accumulated over the experiment(Fig. 4A) was significantly lower in the controls retained inplastic pots than in all treatments that had been applied inthe earthenware tubes; this may reflect the smaller rootingvolume available to the plants in pots. There were nosignificant differences in total dry mass between the plantsfrom three treatments in tubes. The number of tillersproduced per plant did not differ significantly between anyof the treatments. This apparent stability was achievedthrough very different patterns of resource allocation in thetreatments. The shoot dry mass per plant was significantlygreater for plants that received 2 and 4 cm week−" of sanddeposition than for plants receiving no sand, which in turnwas significantly greater than the ‘controls ’ (Fig. 4B). Thepattern for root biomass was almost the inverse of this, withplants receiving 4 cm week−" yielding significantly less thanthe no-accretion or control treatments but not significantlyless than plants receiving 2 cm week−" accretion (Fig. 4C).This led to strikingly and significantly lower root massratios (root mass}total mass) in plants experiencing ac-cretion; the control values were also significantly greaterthan those from the tubes with no accretion, suggesting thatrooting volume, nutrient limitation or shade contributed tothe responses observed (Fig. 4D). The significantly longerleaves in plants given 2 and 4 cm week−" of sand depositionand the fact that leaves in the controls were significantlyshorter than those from the tubes receiving no sand (Fig.4E) also implicate light in the response. The much greaternumber of dead leaves per plant in the controls (Fig. 4F)probably reflects the fact that the low shoot biomass andshoot-mass ratio was associated with high leaf turnover ;within the tubes, numbers of dead leaves increased steadilywith accretion rate.

Effects of salinity on the growth of seedlings

The growth responses of plants of the three populationsto challenges with increasing salinities are shown in Fig. 5.Increasing salinity reduced the dry mass of roots andshoots, leaf area, leaf length and the number of leaves of allpopulations. The coastal population, from Thorla! ksho$ fn,was consistently more tolerant of salinity than the inlandpopulations from Keldur and Sandvı!k. The total dry massof the coastal population was significantly less reduced bytreatment with 400 and 600 m NaCl (Fig. 5A) than thoseof the inland ones, and this tolerance was attributable moreto effects on root dry mass (Fig. 5C) than on shoot dry mass(Fig. 5B). The most obvious difference was in tillerproduction (Fig. 5D): tiller number was stimulated only inthe coastal population at 200–400 m NaCl, such that at400 m its relative production of tillers was nearly threetimes that of the two inland populations. The coastalpopulation maintained a larger leaf area, relative to thenon-saline control, at all salinities but the difference wasonly significant at 600 m, when leaf areas were small (Fig.5E). There was no difference between the populations in theeffect on leaf length (Fig. 5F) and there was no evidencethat salinity treatment caused mortality in any population.

DISCUSSION

The sand accretion rates of about 35 cm per summerrecorded in Leymus dunes at Krosssandur in the south ofIceland were high by any standards (e.g. Olson, 1958; vander Valk, 1974) and emphasize the severe conditionsencountered by germinating seeds. Net accumulation wasmore or less confined to the period from Jul. to Sep.This presumably reflects changes in the balance betweenerosive and accreting effects arising from variations in windspeed and direction (Harris and Davy, 1986). It alsocoincides with the main growing season of L. arenarius inIceland, when the new seedlings would become established;however it is probably also the period when the potentiallysand-trapping leaf cover of L. arenarius is best developed.

The ability of Leymus arenarius seedlings to emerge fromsubstantial burial with sand was clearly demonstrated.Although emergence declined with increasing depth, a highproportion of buried germinating seeds emerged from up to10 cm and there was reasonable emergence from 15 cm;none emerged from 20 cm. Clarke (1965) reported that theemergence of L. arenarius seeds of unspecified mass waslimited by sand burial to 12±7 cm and that only 50%emerged from only 7±6 cm. This relatively poor emergencemight have been the result of small seed size, as Harris(1982), also working with British material, found that 50%of seedlings emerged from 12±7 cm depth of sand burialwithin 67 d but none emerged from a depth of 17±8 cm. Themean seed mass of 11±2 mg was similar to those in ourexperiment and thus the effective limit to L. arenariusemergence from sand burial probably lies between 15 cmand 17±8 cm. The mean potential for leaf elongation in thedark (etiolation) of about 16 cm corresponded well with thisemergence limit. Etiolation potential is thus a good andconvenient predictor of the ability of germinating seeds to


100

0Control

Sand accretion treatment (cm week–1)

Lea

f le

ngt

h (

cm)

60

40

20

80

0 2 4

a

b

c cE4

0Control

Nu

mbe

r of

dea

d le

aves

3

2

1

0 2 4

a

bbc

c

F

1.6

0Control

Roo

t dr

y m

ass

(g)

0.8

0.4

1.2

0 2 4

a

a

ab

b

C0.6

0Control

Roo

t m

ass

rati

o

0.4

0.2

0 2 4

a

b

c

c

D

4

0Control

Tota

l dry

mas

s (g

) 3

2

1

0 2 4

a

bb bA

3

0Control

Sh

oot

dry

mas

s (g

)

2

1

0 2 4

a

b

cc

B

F. 4. Effects of different sand accretion treatments on the growth of seedlings of Leymus arenarius. Treatments : 0 (9), 2 (8) and 4 (+) cmweek−" of sand addition in 30 cm earthenware tubes, and controls (*) retained in plastic plant pots. The values represent mean performance perplant at final harvest. A, Total dry mass ; B, shoot dry mass ; C, root dry mass ; D, root-mass ratio (root dry mass}total dry mass) ; E, length oflongest leaf ; F, number of dead leaves. Means were compared using one-way ANOVA (n¯ 10) and subsequently Tukey’s multiple range test.

Means with the same letter are not significantly different at P! 0±05.

emerge from burial with sand, even though it takes noaccount of the penetrative force required. Seeds of L.arenarius exhibit great variation in mass between popu-lations, between spikes in a population and even withinspikes and spikelets (Greipsson and Davy, 1995). Thestrong dependence of etiolation potential on seed masssupports the idea that larger, better-endowed seeds wouldbe at a considerable advantage under rapidly accretingconditions. Estimates of the proportion of seeds likely toemerge from any depth could be made from their massdistribution, using fitted curves of the type shown in Fig. 2.

The ability of young seedlings to grow through rapid sandaccretion is similarly impressive.Germination ofL. arenariusin the field in Iceland normally begins in late April or earlyMay (Sigurbjo$ rnsson, 1960). Hence seedlings should have atleast 2 months for establishment before they have to copewith substantial sand accretion. The accretion experimentreported here using 10-week old seedlings should have been

a reasonable simulation of the field situation, even thoughconditions in the glasshouse were undoubtedly morefavourable for rapid growth than those in the field. Plantsresponded to burial by allocating biomass to shoot (lowerroot-mass ratios) and leaf (longer leaves) growth ratherthan to the roots, much as has been reported after completeburial in seedlings of the related fore-dune grass Elymusfarctus (Harris and Davy, 1987). Total biomass was slightlybut not significantly increased by the sand additions.Stimulation of growth by moderate accretion treatmentshas been reported in the dune grasses Festuca arenaria (F.rubra ssp. arenaria) by Anderson and Taylor (1979) andAgropyron psammophilum (Zhang and Maun, 1990). Thereis also evidence of enhanced rates of photosynthetic CO

#

uptake after emergence from burial in Ammophilabre�iligulata and Calamo�ilfa longifolia (Yuan, Maun andHopkins, 1993). The stimulatory effect might have beenmore marked in our experiment had it not been for nutrient


600

100

0Concentration of sodium chloride solution (mM)

Rel

ativ

e le

af a

rea

(%)

60

40

20

200 400

80

b

a

ab

a b

a

a

bb

E

600

100

0

Rel

ativ

e le

af le

ngt

h (

%)

60

40

20

200 400

80

aa

a

Fa

aa a

a a

600

100

0

Rel

ativ

e ro

ot d

ry m

ass

(%)

60

40

20

200 400

80

b

b

a

a

a

a

a

bb

C

600

120

0

Rel

ativ

e ti

ller

nu

mbe

r (%

)

60

40

20

200 400

80

b

aa

a

bc

Da

a

600

100

0

Rel

ativ

e to

tal d

ry m

ass

(%)

60

40

20

200 400

80

b

aa

a

a

bb

A

600

100

0

Rel

ativ

e sh

oot

dry

mas

s (%

)

60

40

20

200 400

80

a

a

a

bb

B

a

a

a

b

100

a

b

a

F. 5. Growth responses of seedlings of Leymus arenarius to a salinity gradient represented by challenges with sodium chloride solutions on a3-d cycle in sand culture. Plants from one coastal population, Thorla! ksho$ fn (+) are compared with those from two inland populations, atKeldur (^) and Sandvı!kur (D). Responses shown are relative to mean plant performance in the absence of treatment with sodium chloride. A,Total dry mass ; B, shoot dry mass ; C, root dry mass ; D, number of tillers ; E, leaf area; F, length of longest leaf. Data were root-arcsinetransformed, before populations at each salinity level were compared using one-way ANOVA and Tukey’s multiple range test. Populations at

any salinity with the same letter are not significantly different at P! 0±05.

limitation and the shading effects of the earthenware tubesin the early stages of sand addition. The sand used in thisexperiment was from a deep quarry and did not containmacronutrients that could explain the increased growth;furthermore, no extra adventitious-root development wasobserved as a result of sand addition. Like Ammophilaspecies, L. arenarius flourishes where sands are drifting butits stands begin to decline in vigour as soon as sands arestabilized (Runo! lfsson, 1978).

Leymus arenarius is a highly salt-tolerant species (Benecke,1930; Benecke and Arnold, 1931; Sykes and Wilson, 1989)that can accumulate high concentrations of glycine betaine,a compatible osmotic substrate in halophytes (Stewart et al.,1979; Smirnoff and Stewart, 1985). It is also amongst thestrandline and dune species that are most tolerant of saltspray (Sykes and Wilson, 1988), probably because it has athick layer of epicuticular wax on the leaves, like its closerelative Leymus mollis (Klebesadel, 1985). Our findings also

showed significantly greater tolerance in the growthresponses of seedlings from a coastal population comparedwith those of seedlings from inland populations. Similarlygreater tolerance of coastal populations at the seedgermination stage has already been reported (Greipsson andDavy, 1994b). The increased tiller production in the coastalpopulation when challenged with sodium chloride solutionsof 200–400 m was in strong contrast to the behaviour ofthe inland populations, although the underlying mechanismfor this phenomenon is not yet clear. Total dry mass wassignificantly less reduced by high salinity in the coastalpopulation than in the inland ones and this was mainlythrough an effect on root biomass. Such populationdifferentiation in salinity tolerance is most likely to have astrong genetic component, even though further work wouldbe required to establish this, because of the possiblephenotypic carryover effects when using seed collecteddirectly from the field. Salt-resistant ecotypes of the


essentially non-halophytic grasses Festuca rubra andAgrostis stolonifera are well-known (Hannon and Bradshaw,1968; Tiku and Snaydon, 1971; Ahmad and Wainright,1977). Previous work on inland and coastal populations ofthe dune grass Ammophila bre�iligulata did not find anydifferentiation with respect to salinity tolerance (Seneca andCooper, 1971) but Altai wildrye (Leymus angustus) popu-lations showed genetic variation for epicuticular waxproduction (Jefferson, 1994). Gorham, McDonnell andWyn Jones (1984) compared four Leymus species (L.giganteus, L. angustus, L. sabulosus and L. triticoides) inhydroponic culture and found that their biomass variedbetween 46 and 78% of controls after 2 weeks oftreatment with 200 m NaCl. Direct comparisons aredifficult because of the different culture and treatmenttechniques employed.

Clear practical recommendations can be made from thiswork. The only practicable source of Leymus arenarius seedfor reclamation projects at present is by harvesting fromwild populations. There is large variation in the mean seedmass of the populations available (Greipsson and Davy,1995). The results reported here indicate that there would beclear benefits for establishment in selecting large-seededsource populations for the revegetation of areas withpotentially high sand accretion rates. Drilling at 5–10 cmdepth would allow good emergence and yet avoid the severedesiccation risk of the surface layers of sand. At sites wherethere is a coastal influence, there would be further advantagein using seed exclusively from coastal populations, bothbecause of its greater tolerance of salinity for germination(Greipsson and Davy, 1994b) and because of the greatertolerance to salinity of growth in the resulting seedlings.

ACKNOWLEDGEMENTS

S. Greipsson was supported by awards from the Committeeof Vice-Chancellors and Principals of Universities of Britain(ORS), the Foreign and Commonwealth Office (FCO) andthe Icelandic Environmental Protection Society. The SoilConservation Service of Iceland also supported this workfinancially.

LITERATURE CITED

Ahmad J, Wainwright SJ. 1977. Tolerance to salt, partial anaerobiosisand osmotic stress in Agrostis stolonifera. New Phytologist 79 :605–612.

Anderson C, Taylor K. 1979. Some factors affecting the growth of twopopulations of Festuca rubra var. arenaria on the dunes ofBlakeney Point, Norfolk. In: Jefferies RL,Davy AJ, eds. Ecologicalprocesses in coastal en�ironments. Oxford: Blackwell ScientificPublications, 129–144.

Barbour MG, de Jong TM, Pavlik BM. 1985. Marine beach and duneplant communities. In:ChabotBF,MooneyHA, eds.Physiologicalecology of North American plant communities. New York:Chapman and Hall, 296–322.

Benecke W. 1930. Zu$ r Biologie der Strand- und Du$ nenflora. l.Vergleichende Versuche u$ ber die Saltztoleranz von Ammophilaarenaria Link, Elymus arenarius L. und Agropyron junceum L.Bericht der Deutschen botanischen Gesellschaft 48 : 127–139.

Benecke W, Arnold A. 1931. Zu$ r Biologie der Strand und Du$ nenflora,ll. Der Salzgehalt der naturlichen Standorte von Agropyronjunceum P.B. und Ammophila arenaria Roth auf dem Sandstrande

von Norderney. Bericht der Deutschen botanischen Gesellschaft 49 :363–381.

Bond TET. 1952. Biological flora of the British Isles. Elymus arenariusL. Journal of Ecology 40 : 217–227.

Clarke SM. 1965. Some aspects of the autecology of Elymus arenariusL. PhD thesis University of Hull, UK.

De Jong TM. 1979. Water and salinity relations of Californian beachspecies. Journal of Ecology 67 : 647–663.

Davy AJ, Figueroa ME. 1993. The colonization of strandlines. In:Miles J, Walton DWH, eds. Primary succession on land. Oxford:Blackwell Scientific Publications, 113–131.

Gorham J, McDonnell E, Wyn Jones RG. 1984. Salt tolerance in theTriticeae: Leymus sabulosus. Journal of Experimental Botany 35 :1200–1209.

Greipsson S, Davy AJ. 1994a. Leymus arenarius. Characteristics anduses of a dune-building grass. Icelandic Agricultural Sciences 8 :41–50.

Greipsson S, Davy AJ. 1994b. Germination of Leymus arenarius and itssignificance for land reclamation in Iceland. Annals of Botany 73 :393–401.

Greipsson S, Davy AJ. 1995. Seed mass and germination behaviour inpopulations of the dune-building grass Leymus arenarius. Annalsof Botany 76 : 493–501.

Greipsson S, El-Mayas H. 1996. The stabilization of coastal sands inIceland. In: Jones PS, Healy MG, Williams AT, eds. Studies inEuropean coastal management. Cardigan, UK: Samara Publishing(in press).

Hannon N, Bradshaw AD. 1968. Evolution of salt tolerance in two co-existing species of grass. Nature 220 : 1342–1343.

Harris D. 1982. Growth responses of Elymus farctus to disturbancesencountered in the strandline. PhD thesis, University of EastAnglia, Norwich, UK.

Harris D, Davy AJ. 1986. Strandline colonization by Elymus farctus inrelation to sand mobility and rabbit grazing. Journal of Ecology74 : 1045–1056.

Harris D, Davy AJ. 1987. Seedling growth in Elymus farctus afterepisodes of burial with sand. Annals of Botany 60 : 587–593.

Hoagland DR, Arnon DI. 1938. The water-culture method for growingplants without soil. California Agricultural Experimental StationCircular 347.

Jefferson PG. 1994. Genetic variation for epicuticular wax productionin Altai wildrye populations that differ in glaucousness. CropSciences 34 : 367–371.

Klebesadel LJ. 1985. Beach wildrye. Characteristics and uses of a nativeAlaskan grass of uniquely coastal distribution. Agroborealis 17 :31–38.

Maun MA, Lapierre J. 1986. Effects of burial by sand on seedgermination and seedling emergence of four dune species. AmericanJournal of Botany 73 : 450–455.

Olson JS. 1958. Lake Michigan dune development. II. Plants as agentsand tools of geomorphology. Journal of Geology 66 : 345–351.

Rozema J, Bijwaard P, Prast G, Broekman R. 1985. Ecophysiologicaladaptations of coastal halophytes from foredunes and salt marshes.Vegetatio 62 : 499–521.

Runo! lfsson S. 1978. Soil conservation in Iceland. In: Holdgate W,Woodman MJ, eds. The breakdown and restoration of ecosystems,NATO Conference Series, Serie 1 Ecology. New York: PlenumPress, 231–240.

Runo! lfsson S. 1987. Land reclamation in Iceland. Arctic and AlpineResearch 19 : 514–517.

Seneca ED, Cooper AW. 1971. Germination and seedling response totemperature, daylength, and salinity by Ammophila bre�iligulatafrom Michigan and North Carolina. Botanical Gazette 132 :203–215.

Sigurbjo$ rnsson B. 1960. Studies on the Icelandic Elymus. PhD thesis,Cornell University, Ithaca, New York.

Smirnoff N, Stewart GR. 1985. Stress metabolites and their role incoastal plants. Vegetatio 62 : 273–278.

Stewart GR, Larher F, Ahmed I, Lee JA. 1979. Nitrogen metabolismand salt tolerance in higher plant halophytes. In: Jefferies RL,Davy AJ, eds. Ecological processes in coastal en�ironments. Oxford:Blackwell Scientific Publications, 211–227.

Sykes MT, Wilson JB. 1988. An experimental investigation into the


response of some New Zealand sand dune species to salt spray.Annals of Botany 62 : 159–166.

Sykes MT, Wilson JB. 1989. The effect of salinity on the growth ofsome New Zealand sand dune species. Acta Botanica Neerlandica38 : 173–182.

Sykes MT, Wilson JB. 1990. Dark tolerance in plants of dunes.Functional Ecology 4 : 799–805.

Tiku BL, Snaydon RW. 1977. Salinity tolerance within the grass speciesAgrostis stolonifera. Plant and Soil 35 : 421–431.

van der Valk AG. 1974. Environmental factors controlling thedistribution of forbs on coastal foredunes in Cape Hatterasnational seashore. Canadian Journal of Botany 52 : 1057–1073.

Yuan T, Maun MA, Hopkins WG. 1993. Effects of sand accretion onphotosynthesis, leaf-water potential and morphology of two dunegrasses. Functional Ecology 7 : 676–682.

Zhang J, Maun MA. 1990. Effects of sand burial on seed germination,seedling emergence, survival, and growth of Agropyron psammo-philum. Canadian Journal of Botany 68 : 304–310.

sand accretion and salinity as constraints on the establishment ofleymus arenariusfor land...

Documents