American Journal of Plant Sciences, 2013, 4, 1899-1910
http://dx.doi.org/10.4236/ajps.2013.49233 Published Online September 2013 (http://www.scirp.org/journal/ajps)
Sand Dune Species Distribution and Size Variations in Two
Areas Inside a Natural Protected Area Subjected to
Different Human Disturbance
Loretta Gratani, Maria Fiore Crescente, Laura Varone, Emanuela Gini, Carlo Ricotta, Andrea Bonito
Department of Environmental Biology, Sapienza University of Rome, Rome, Italy.
Received June 28th, 2013; revised July 30th, 2013; accepted August 15th, 2013
Copyright © 2013 Loretta Gratani et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Sand dune species were analyzed across two areas included in the “Roman Coastal State Nature Reserve” (Italy): Ostia
(O) and Marina di Palidoro (P). Significant variations in species distribution, dry mass and size over the gradient from
the water-edge toward the inland between O and P were observed. Species colonize O, on an average, at 79 m from the
water-edge extended along the gradient toward the inland over a length of 26 m. PD is 40.8 ± 9.9 plants·m−2. Ononis
variegata and Elymus farctus have the highest PD (15.4 ± 1.3 plants·m−2), followed by Silene colora ta and Sporobulus
pungens (4.3 ± 3.9 plants·m−2), by Cakile maritima, Echinophora spino sa, Eryngium maritimum, Ammophila arenaria,
Anthemis maritima, Cyperus capitatus, Medicago marina and Calystegia soldanella (<0.5 plants·m−2), with C.
soldanella having the lowest PD (0.02 plants·m−2). On an average, in P, the species colonize the dune at 17 m from the
water-edge for a length of 46 m toward the inland, PD is on an average 21.5 ± 16.1 plants·m−2. S. pungens, E. farctus
and O. variegata have the highest PD (6.0 ± 2.4 plants·m−2), followed by C. capitatus (2.1 ± 4.7 plants·m−2), by S. col-
orata and A. maritima (0.4 ± 0.1 plants·m−2) and by E. spinosa, E. maritimum, M. marina, Pancratium maritimum and C.
soldanella (0.2 plants·m−2). The results underline a larger species presence along the gradient from the water-edge to-
ward the inland in P site compared to O site where, on the contrary, plants exclusively colonize the inner dune area due
to the strong human disturbance which causes the foredune to become flat. Nevertheless, the presence of the most im-
portant autoctonous sand dune species (on an average, 15.3 ± 0.5 species) can provide information for restoring the
perturbed dune areas when preparing management strategies considering that the maintenance of coastal areas depends
on the maintenance of native species.
Keywords: Dune Vegetation; Human Disturbance; Plant Density; Organic Soil Matter
1. Introduction
Some critical factors affect the survival and distribution
of coastal sand dune species which grow on a physiologi-
cally dried substrate characterised by a low mineral con-
tent [1-4]. A factor which contributes to select dune spe-
cies is the climatic effect on sand movements [5,6] such
as wind-speed entrainment thresholds for sand particles
and salt burial [7,8]. With regard to species assemblage,
dune-builder plants may grow on fore-dunes, burial-tol-
erant plants on inter-dunes and shrubs on stabilized
dunes [9]. Morphological and physiological plant adapta-
tions are important especially on fore-dunes [10-12]
where few species are capable of withstanding the stress
factors imposed by limited environmental resources and
recurrent disturbance. On older dunes, where salt spray,
nutrient and water are no longer exclusive limiting fac-
tors, competition for space and light may affect species
richness [13-15]. Plant species presence is also related to
organic matter which varies from water-edge toward the
inland [11,13].
The ecological state of sea coasts is often critical
worldwide [16]. In Europe most of the well conserved
coastal dune areas are at present under protection [17]
and are included in the EU Directive Habitat 92/43/CEE.
Nevertheless, dunes are the most threatened habitats by
the expansion of urban areas and the development of
seaside tourism [9,18] leading to the fragmentation of
vegetation and the disappearance of vegetation bands
developing on mobile dunes [19]. Disturbance is defined
as a stochastic event in opposition to environmental
stress which is predictable and rather continuous [20].

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1900
Most common environmental stress factors are drought
and soil nutrient deficiency [21]. Among human distur-
bance, infrastructure development is widespread on
coasts in Europe. Furthermore, landscape fragmentation
disrupts large scale geo-morphological processes [22]
and mechanical damages through trampling reduce or
even destroy vegetation [13]. Increased knowledge of
plant species response to stress factors (i.e. climate, soil,
anthropogenic interference) aims at the long-term land
use planning to ensure sustainability of coastal resources
while providing management flexibility for the future
[23].
The main objective of this research was to compare the
species presence in two areas included in a natural pro-
tected area developing along the Tyrrhenian coast near
Rome and subjected to a different human disturbance.
Considering the importance of biological diversity main-
tenance [24-27], we analyzed variations in sand dune
species presence, dry mass and size over the gradient
from the water-edge toward the inland.
2. Methods
2.1. The Study Area
The study was carried out in the year 2012 in the Roman
Coastal State Nature Reserve (Italian decree of 1996)
which extended for ca 43 Km along the Tyrrhenian coast
near Rome (Italy). Two areas were selected: Ostia
(41˚41'00"N 12˚22'39"E) and Marina di Palidoro
(41˚54'43"N 12˚08'47"E) (Figure 1). Despite the two
areas being under protection, in recent years they were
subjected to human disturbance. In particular, Ostia (O)
was a small populated city (85,301 people/km2, data
from Rome Municipality for the year 2010) where nu-
merous buildings and bathing establishments were built
in the last 50 years. Two sub-areas were selected for
measurements: O1 (41˚40'58"N, 12˚22'40"E) near a gully,
extending along the coast line for ca 200 m, and O2
(41˚40'37"N, 12˚23'14"E) near a bathing establishment,
extending along the coastline for ca 400 m. At both O1
and O2 the sand dune appeared flat up to 70 - 80 m from
the water-edge, followed by a mobile dune area charac-
terised by a moderate slope of ca 6%, which finished
with the fixed dune colonized by Mediterranean shrubs.
The distance from the water-edge to the shrubby layer
was 109 m and 100 m in O1 and O2, respectively. Dune
species were present at 85 and 73 m from the water-edge
in O1 and O2, respectively.
Marina di Palidoro (P) was characterized by a lower
human disturbance than O because of few buildings and
bathing establishments. Two sub-areas were selected in P
for measurements: P1 (41˚55'06"N, 12˚08'17"E) near the
hospital Bambino Gesù, extending along the coast line
for ca 1600 m, and P2 (41˚54'43"N, 12˚08'46"E) near a
block of flats, extending along the coast line for ca 700 m.
In P1 and P2 the drift line and the foredune extended
along the gradient from the water-edge toward the inland
for ca 33 m and 41 m, respectively, was characterized by
a moderate slope (ca 2%). Then it was followed by a
mobile dune area extending for ca 20 m and 32 m in P1
and P2, respectively, and by the fixed dune with Medi-
terranean shrubs. The distance from the water-edge to the
Figure 1. The two studied areas along the Thyrrenian coast near Rome, Ostia (O, 41˚41'00"N, 12˚22'39"E) and Marina di
alidoro (P, 41˚54'43"N, 12˚08'47"E), and the considered sub-areas (O1, O2, P1 and P2) are indicated. P

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1901
shrubby layer was 53 m and 73 m for P1 an d P2, respec-
tively. Species were present at 20 and 15 m from the wa-
ter-edge, in P1 and P2 respectively.
A transect oriented from the water-edge toward the
inland was established in each of the selected sub-areas
(O1, O2, P1, P2) for vegetation sampling. Along each
transect, plots (10 × 10 m each) were established, 3 m
apart, starting from the water-edge to the inland (i.e.
Mediterranean shrubby). Plot numbers were established
in relation to the extension in length of the dune from
water edge toward the inland and to species presence. In
each sub-area the first plot was established where the
first species presence occurred. In particular, two plots
were established in O1 (O1a, and O1b at 85 and 98 m from
the water edge, respectively), O2 (O2a, O2b at 73 m and 86
m from the water edge, respectively), and in P1 (P1a and
P1b at 20 and 33 m from the water-edge, respectively),
and four plots in P2 (P2a, P2b, P2c and P2d at 15, 28, 41 and
54 m from the water-edge, respectively).
2.2. Climate and Microclimate
The selected areas were characterised by a Mediterranean
type of climate. At O, the total annual rainfall was 589
mm, the mean minimum air temperature of the coldest
months (January and February) was 4.8˚C and the mean
maximum air temperature of the warmest months (July
and August) was 29.1˚C (data from the Meteorological
Station of Pratica di Mare, for the years 2000-2012)
(Figure 2). At P, the total annual rainfall was 556 mm,
the mean minimum air temperature of the coldest months
(January and February) was 3.2˚C and the mean maxi-
mum air temperature of the warmest months (July and
August) was 29.6˚C (data from the Meteorological Sta-
tion of Fiumicino, for the years 2000-2012) (Figure 2).
The dominant winds were from W and the others from S
and SE. The mean yearly winds speed was 16.6 knots
and 18.7 knots at O and P, respectively [28].
Microclimate was measured in the considered sub-ar-
eas at 20, 40, 60, 80, 100 m from the water-edge toward
the inland, periodically (twice a month) during the study
period. In each sampling occasion, air temperature (T,
˚C), relative air humidity (RH, %), total irradiance (I,
μmol photon m−2·s−1) and wind speed (W, m/s) were re-
corded at 50 cm from the sand level. On each sampling
occasion, measurements were carried out at 12:00 a.m.
Figure 2. Climate diagrams of Ostia (O) and Marina di Palidoro (P) (data from the Meteorological Station of Pratica di Mare
and of Fiumicino, respectively, for the period 2000-2011). Total monthly rainfall (R, mm, columns), mean monthly air tem-
erature (T, ˚C, lines), annual mean temperature (Tann.mean) and total annual rainfall (Rtot) are shown. p

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1902
Air temperature and air humidity were measured by a
thermo-hygrometer (HD8901, Delta Ohm, I), total ir-
radiance by a radiometer (LI-185B with a 190SB Quan-
tum Sensor, LI-COR, USA) and wind speed by an ane-
mometer (LUTRON AM-4201).
2.3. Sand Characterization
Triplicate sand samples were collected in the considered
sub-areas at 20, 40, 60, 80, 100 m from the water-edge,
for determination of sand water content (SWC, %), pH,
soil organic matter (SOM, %) content and total nitrogen
(N, %) content. All sand samples were collected at the
end of May (at least 5 days after the last rainfall) at a
depth of 40 cm by a drill. Sand samples were transported
immediately to the laboratory. Sand samples were air
dried at room temperature and then passed through 2 mm
sieve. SWC was determined on sand samples (500 g each)
as fresh sand minus dry sand divided by dry sand percent,
calculated after oven-dried at 90˚C to a constant mass. The
pH was measured with a glass electrode in a suspension
of sand in deionized water. SOM was determined col-
orimetrically with potassium dichromate, according to [29]
and the N content by Kjeldahl method, according to [30].
2.4. Plant Species Presence and Plant Traits
Species presence was recorded in the considered plots
from May to June, corresponding to the maximum plant
biomass [31,32]. The number of plants per species was
counted in each plot to calculate plant density (PD, indi-
viduals·m–2).
Measurements of plant traits were carried out on rep-
resentative plant species (5 plants per species in each plot)
at the beginning of June. It included plant height (H, m),
total plant volume per plot (V, cm3·m–2), total plant area
per unit of covered area at sand level (PA, cm2·m–2) and
total aboveground plant biomass (TPB, g·m–2). Plant
material was harvested, oven dried and then weighed to
obtain dry mass (DM, g), according to [33]. TPB per
species was calculated by multiplying DM and PD. H
was defined as the maximum vertical distance from the
sand level to the highest point of the plant. V was calcu-
lated by the volume of a cylinder, according to [34].
2.5. Statistical Analysis
The main gradients in species composition were ex-
tracted by ordination (principal coordinate analysis,
PcoA) which was performed on the plot-to-plot dissimi-
larity matrix and calculated with the Jaccard coefficient
for species presence and absence data.
Differences of the means for the considered traits were
tested by one-way ANOVA, and Tukey test for multiple
comparisons. Kolmogorov-Smirnov and Levene tests
were used to verify the assumption of normality and ho-
mogeneity of variances, respectively.
All statistical tests were performed by using Statistica
6.0 (Statsoft, USA). All data were shown as mean ± S.D.
3. Results
3.1. Microclimate and Sand Characterization
The microclimate of the considered sub-areas (P1 and P2
and O1 and O2) is shown in Figure 3. In all the consid-
ered sub-areas, T increased by 15% from water-edge to
the inland, while RH and I decreased by 13%, 6% re-
spectively (mean of P1, P2, O1 and O2). The wind (W)
action decreased, on an average, 56% from water-edge
toward the inland, both in O and P sub-areas.
The O and P sand characterization is shown in Figure
4. In the considered sub-areas, SWC and pH decreased
on an average, 18% and 11% from the water-edge toward
the inland, respectively, while SOM and N content in-
creased more than 100% and 113%, respectively (mean
of O and P).
3.2. Plant Traits
Data on species presence, PD, H, V, PA and TPB in the
considered plots are shown in Table 1. The number of
species was larger in P (15.5 ± 0.5, mean of P1 and P2
plots) than in O (14.5 ± 0.5, mean of O1 and O2 plots). A
larger PD was monitored in P1b, and P2c, (37.7 ± 3.1
plants·m–2, mean value) and in O1b and O2b (48.8 ± 0.15
plants·m–2, mean value) than in the other plots (22.1 ±
14.3 plants·m–2, mean value). Crucianella maritima (PD
= 0.53 plants·m–2, mean value) was monitored only in P2d.
The plots farer from the water-edge had a higher H than
those closer to it. In particular, H was on an average 59%
higher in O1b than in O1a and 70% higher in O2b than in
O2a. H was 41% higher in P1b than in P1a, and 74% higher
in P2c and P2d than in P2a and P2b. On an average, PA was
82% larger in O1b than in O1a and 94% larger in O2b than
in O2a. PA was 266% larger in P1b than in P1a, and 577%
larger in P2c and P2d than in P2a and P2b. TPB ranged from
1145.8 g·m–2 (in O) to 1413.0 g·m–2 (in P) and it was the
highest in O2b (304.9 g·m–2) among O plots, and in P2d
(394.4 g·m–2) among P plots.
As regards to the species, E. farctus had the highest
TPB and V (141.6 ± 62.2 g·m–2 and 19837 ± 8885
cm3·m–2 respectively, mean of the considered P and O
plots) and Chamaesyce peplis the lowest one (0.008 ±
0.010 g·m–2 and 1.9 ± 2.1 cm3·m–2 respectively, mean of
the considered P and O plots).
3.3. Principal Coordinate Analysis
PCoA extracted two factors accounting for 53.33% of the

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1903
Figure 3. Air temperature (T, ˚C), relative air humidity (RH, %), total irradiance (I, μmol photons m–2·s–1) and wind speed
(W, m·s–1) measured at 50 cm from the sand level, at 12:00 a.m., in the considered sub-areas at Ostia (O1, O2) and at Marina
di Palidoro (P1 and P2). Measurements were carried out at 20, 40, 60, 80, 100 m from water-edge. Mean values ± standard
deviation are shown. For each sub-area different letters indicate significant differences among the distances over the gradient
from the water-edge toward the inland.

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1904
Figure 4. Sand water content (SWC, %), pH, soil organic matter (SOM, %) and total nitrogen content (N, %) collected in the
considered sub-areas in Ostia (O1, O2) and Marina di Palidoro (P1 and P2) at 20, 40, 60, 80, 100 m from water-edge. Mean
values ± standard deviation are shown. For each distance over the gradient from the water-edge toward the inland sub-area
different letters indicate significant differences among the sub-areas.

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1905
Table 1. Data on species presence, plant density, plant height, plant area, plant volume and total plant biomass of the
considered plots used in this study. For each species different letters indicate significant differences among the plots.
Distance (m) 85 - 95 98 - 10873 - 8386 - 9620 - 3033 - 4315 - 25 28 - 38 41 - 5154 - 64
Plot
Species O1a O
1b O 2a O 2b P 1a P 1b P 2a P 2b P 2c P 2d
PD (plant·m−2) PD (plant·m−2) PD (plant·m−2) PD (plant·m−2)
Cakile maritima Scop. 0.01 a - - 0.01 a0.02 a- 0.88 b - 0.02 a-
Echinophora spinosa L. 0.05 a 0.12 b0.07 a0.11 b0.02 a0.07 a - 0.02 a 0.16 c0.25 d
Eryngium maritimum L. - 0.01 a- 0.10 b0.07 ab0.03 a - 0.15 c - 0.15 c
Elymus farctus (Viv.) Runemark
ex Melderis 18.60 a 12.09 b20.70 a14.00 b11.85 b5.15 c - 9.00 d 13.15 b5.04 c
Ammophila arenaria (L.) Link - 1.16 a- 0.80 ac- 0.14 b - - 0.54 c-
Anthemis maritimaL. 0.26 a 0.39 b0.14 a0.58 b0.05 c1.36 d - - 0.18 a0.59 b
Cyperus capitatus Vand. - 0.59 ab- 0.31 a- 0.79 b - - - 11.75 c
Ononis variegataL. 0.14 a 28.3 b- 29.40 b- 13.25 c- - - 6.02 d
Medicago marinaL. - 0.15 a0.02 b0.02 b- 0.04 b - - - 0.12 a
Crucianella maritimaL. - - - - - - - - - 0.53
Calystegia soldanella(L.) R. Br. 0.02a - - - - 0.03 a - - - 0.06 b
Sporobolus pungens(Schreb.) Kunth 16.55a 2.85 b7.85 c1.20 d- 13.00 e- 0.15 f 25.75 g5.50 c
Silene colorataPoir. 0.71a 3.10 b0.04 c2.45 b- 0.92 d - - - 1.43 e
Pancratium maritimumL. - 0.01a - 0.01 a0.03 ac0.71 b - - 0.01 a0.05 c
Salsola kaliL. 0.12a - 0.01 b- 0.02 b- 0.07 c 0.12 a 0.04 bc-
Chamaesyce peplis (L.) Prokh. 0.01a - 0.01 a- 0.01 a- - - 0.08 b-
Total 17.54 48.76 28.8248.96 12.04 35.46 0.07 9.43 39.91 31.46
H (cm) H (cm) H (cm) H (cm)
Cakile maritima Scop. 22.0 a - - 35.0 b11.5 c- 16.5 d - 19.3 d-
Echinophora spinosa L. 40.6 a 36.5 a29.5 b29.1 b10.8 c21.0 d - 28.5 b 26.6 b17.2 e
Eryngium maritimum L. - 22.5 a- 26.4 b21.8 ac19.3 c - 12.3 d - 24.9 ab
Elymus farctus (Viv.) Runemark
ex Melderis 43.0 a 43.0 a40.5 a64.8 b43.7 a43.5 a - 53.7 c 44.0 a41.0 a
Ammophila arenaria (L.) Link - 92.5 a- 105.0 b- 28.0 c - - 108.1 b-
Anthemis maritimaL. 16.3 a 16.9 ab19.5 b14.6 a13.1 a17.4 ab- - 20.2 b13.3 a
Cyperus capitatus Vand. - 39.0 a- 37.8 a- 36.0 a - - - 44.5 b
Ononis variegataL. 10.1 a 11.5 a- 9.5 a - 9.5 a - - - 11.5 a
Medicago marinaL. - 12.4 a7.8 b 9.3 b - 12.6 a - - - 15.6 a
Crucianella maritimaL. - - - - - - - - - 18.2
Calystegia soldanella(L.) R. Br. 3.5 a - - - - 3.5 a - - - 6.5 b
Sporobolus pungens(Schreb.) Kunth 19.0 ac 19.0 ac17.0 a16.0 a- 10.5 b - 10.1 b 11.0 b21.5 c
Silene colorataPoir. 14.0 a 15.5 a20.0 b14.5 a- 14.0 a - - - 20.0 b
Pancratium maritimumL. - 15.5 a- 17.0 a10.6 b28.5 c - - 38.0 d41.7 d
Salsola kaliL. 10.4 a - 9.8 a - 2.3 b - 2.0 b 2.3 b 2.4 b -
Chamaesyce peplis (L.) Prokh. 4.0 a - 4.5 a - 2.0 b - - - 2.4 b -
Mean 18.3 29.5 18.6 31.6 14.5 20.3 9.3 21.4 30.2 23.0
PA (cm2·m−2) PA (cm2·m−2) PA (cm2·m−2) PA (cm2·m−2)
Cakile maritima Scop. 15.00 a - - 13.35 a4.00 b- 352.00 c - 81.63 d-
Echinophora spinosa L. 136.45 a 321.71 b99.63 c158.77 d3.14 e22.02 f- 4.50 e 232.55 g109.86 c
Eryngium maritimum L. - 4.02 a- 231.43 b22.79 c10.59 c- 49.28 d - 104.26 e
Elymus farctus (Viv.) Runemark
ex Melderis 672.00 a 423.15 b724.50 a490.00 b414.75 b180.25 c- 315.00 d 460.25 b176.40 c
Ammophila arenaria (L.) Link - 29.05 a- 20.00 a- 3.38 b - - 181.03 c-
Anthemis maritimaL. 413.90 a 524.19 b358.68 a654.05 c187.08 d1415.94 e- - 626.01 c887.86 f
Cyperus capitatus Vand. - 28.08 ab- 14.64 a- 37.68 b- - - 564.00 c

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1906
Continued
Ononis variegataL. 41.99 a 707.50 b- 735.00 b- 331.25 c- - - 138.00 d
Medicago marinaL. - 507.74 a12.56 b97.50 c- 104.8 c- - - 495.73 a
Crucianella maritimaL. - - - - - - - - - 498.45
Calystegia soldanella(L.) R. Br. 0.29 a - - - - 1.05 a - - - 11.00 b
Sporobolus pungens(Schreb.) Kunth136.80 a 22.80 b62.80 c9.60 d- 104.00 e- 1.20 f 206.00 g44.00 c
Silene colorataPoir. 4.26 a 18.60 b0.21 c14.70 b- 5.49 a - - - 8.55 d
Pancratium maritimumL. - 1.63 a - 2.72 a1.47 a 101.52 b- - 14.23 c65.89 d
Salsola kaliL. 0.82 a - 0.08 b- 0.10 b - 1.48 c 0.96 a 0.38 d -
Chamaesyce peplis (L.) Prokh. 0.16 a - 0.29 a- 0.28 a - - - 2.12 b -
Total 1421.66 2588.461258.762441.75633.612317.96353.48 370.94 1804.203104.01
V (cm3·m−2) V (cm3·m−2) V (cm3·m−2) V (cm3·m−2)
Cakile maritima Scop. 330.0 a - - 467.1 b46.0 c - 5808.0 d - 1571.3 e-
Echinophora spinosa L. 5543.3 a 11742.2 b2941.2 c4626.5 d33.8 e 461.5 f- 128.3 g 6194.0 h1892.8 i
Eryngium maritimum L. - 90.5 a - 6114.4 b495.8 c204.8 d- 606.9 e - 2598.5 f
Elymus farctus (Viv.) Runemark
ex Melderis 28896.0 a 18195.5 b29342.3 a31752.0 a18106.8 b7840.9 c- 16915.5 b 20251.0 b7232.4 c
Ammophila arenaria (L.) Link - 2686.7 a- 2100.0 a- 94.5 b - - 19576.7 c-
Anthemis maritimaL. 6736.7 a 8862.5 b7008.6 a9569.7 b2447.6 c24605.4 d- - 12629.8 e11801.1 e
Cyperus capitatus Vand. - 1095.1 ab- 552.7 b- 1356.5 a- - - 25098.0 c
Ononis variegataL. 425.6 a 8136.3 b- 6982.5 b- 3146.9 c- - - 1587.0 d
Medicago marinaL. - 6315.7 a97.3 b901.9 c- 1320.4 d- - - 7736.9 a
Crucianella maritimaL. - - - - - - - - - 9090.7
Calystegia soldanella(L.) R. Br. 1.0 a - - - - 3.7 a - - - 71.5 b
Sporobolus pungens(Schreb.) Kunth2599.2 a 433.2 b1067.6 c153.6 d- 1092.0 c- 12.1 e 2266.0 f946.0 c
Silene colorataPoir. 59.6 a 288.3 b4.2 c 213.2 b- 76.9 a - - - 171.0 d
Pancratium maritimumL. - 25.2 a - 46.2 a15.6 a 2893.3 b- - 540.7 c2747.5 b
Salsola kaliL. 8.6 a - 0.8 b - 0.2 b - 3.0 c 2.3 c 0.9 b -
Chamaesyce peplis (L.) Prokh. 0.6 a - 1.3 a - 0.6 a - - - 5.1 b -
Total 44600.6 57871.140463.263479.721146.443096.75811.0 17665.0 63035.370973.5
TPB (g·m−2) TPB (g·m−2) TPB (g·m−2) TPB (g·m−2)
Cakile maritima Scop. 0.250 a - - 0.222 a0.067 b- 5.870 c - 1.361 d-
Echinophora spinosa L. 4.107 a 9.683 b2.999 c4.779 a0.120 e0.662 f- 0.120 e 7.000 g3.307 c
Eryngium maritimum L. - 0.257 a- 14.808 b1.460 c0.678 ac- 3.155 d - 6.671 e
Elymus farctus (Viv.) Runemark
ex Melderis 216.318 a 140.607 b240.741 a162.820 b137.816 b59.895 c- 104.67 d 152.935 b58.615 c
Ammophila arenaria (L.) Link - 20.308 a- 13.984 a- 2.360 c- - 126.574 d-
Anthemis maritimaL. 27.417 a 34.724 b23.760 a43.325 c12.393 d93.795 e- - 41.468 c58.814 f
Cyperus capitatus Vand. - 3.463 ab- 1.806 a- 4.647 b- - - 69.560 c
Ononis variegataL. 2.872 a 48.393 b- 50.274 b- 22.658 c- - 10.294 d
Medicago marinaL. - 34.770 a0.860 b6.677 c- 7.177 c- - - 33.947 a
Crucianella maritimaL. - - - - - - - - - 41.335
Calystegia soldanella(L.) R. Br. 0.007 a - - - - 0.025 a- - - 0.262 b
Sporobolus pungens(Schreb.) Kunth15.391 a 2.651 b7.301 c1.116 d- 12.090 e- 0.140 f 23.948 g5.115 bc
Silene colorataPoir. 0.234 a 1.023 b0.012 c0.809 bd- 0.630 de- - - 0.470 ae
Pancratium maritimumL. - 2.614 a- 4.375 b2.316 a163.306 c- - 22.888 d105.987 e
Salsola kaliL. 0.047 cd - 0.006 a- 0.006 a- 0.084 b 0.063 bc 0.022 d-
Chamaesyce peplis (L.) Prokh. 0.002 a - 0.003 a- 0.003 a- - - 0.023 b-
Total 266.646 298.493275.680304.995154.180367.9225.954 108.150 376.218394.378

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1907
Our results on the whole show significant variations of
species presence and density between Ostia and Marina
di Palidoro in response to the different human distur-
bance. The strong human disturbance at Ostia is the re-
sult of the large presence of beach establishments, nu-
merous buildings, the intense use of mechanical means to
clean the area and a strong human trampling all year long,
which have largely altered the sand dune, and in particu-
lar the foredune. In response to these factors, species
colonize the dune area, on an average, at 79 m from the
water-edge (mean of O1 and O2) extending along the gra-
dient toward the inland over a length of 26 m (mean
value). PD is 40.8 ± 9.9 plants·m–2 (mean of all the con-
sidered O plots). In particular, O. variegata and E. farc-
tus have the highest PD (15.4 ± 1.3 plants·m–2 mean
value), followed by S. colorata and S. pugens (4.3 ± 3.9
plants·m–2, mean value), by Ca. maritima, E. spinosa, E.
maritimum, A. arenaria, A. maritima, C. capitatus, M.
marina and C. soldanella (lower than 0.5 plants·m–2). C.
soldanella is a prostrate plant with long rhizomes that
survives seawater inundation better than many other spe-
cies [40] which causes the aerial parts to die but the bur-
ied rhizome may survive. This species co-occurs with E.
farctus in many other foredune areas in Europe [41]. H
and TPB vary from 18.3 m to 31.6 m and from 266.7
g·m–2 to 305.0 g·m–2, respectively.
total variance. Factor 1 and 2 accounted for 34.80% and
18.53% of the total variance, respectively. The first fac-
tor reflected the turnover of the vegetation along the
sea-inland vegetation zonation, with higher scores of the
factor indicating species closer to the water-edge. Varia-
tion in species composition among plots was greater in
the longer and less disturbed transect of P (P2) as under-
lined by a greater dispersion of the plots in this sub-area
along the second ordination axis (Figure 5).
4. Discussion
The natural vegetation of the Tyrrhenian coast which
includes “The Roman Coast State Nature Reserve” until
the years 1970-1980 was characterised by different
vegetation bands. In particular, after the aphytoic dune
area, the first community on the strandline was charac-
terized by Ca. maritima, E. peplis and Salsola kali, fol-
lowed by a second community on the foredune with E.
farctus, S. pungens, and C. capitatus. The third commu-
nity which contributed to dune consolidation was char-
acterized by A. arenaria, E. spinosa, O. variegata, E.
maritimum and M. marina and the inner community by
Cr. maritima and P. maritimum, followed by the Medi-
terranean maquis [9,35].
In stressful environments, species are patchily distrib-
uted [36-38], however, spatial species aggregation may also
be caused by within-community environmental hetero-
geneity and preference for common micro-habitats [39].
The lower human disturbance at P in respect to O, de-
termines the species presence, on an average, at 14.5 m
from the water-edge extending along the gradient toward
Figure 5. Ordination diagram of the considered plots for Ostia (sub-areas O1 and O2) and Marina di Palidoro (sub-areas P1
nd P2). The variance associated to the first two axes of the principal coordinate analysis is 34.80% and 18.53%, respectively. a

Sand Dune Species Distribution and Size Variations in Two Areas Inside a Natural Protected
Area Subjected to Different Human Disturbance
1908
the inland for a length of 61 m (mean value) and PD is
21.5 ± 16.1 plants·m–2 (mean of all the considered P
plots). In particular, S. pungens, E. farctus and O. varie-
gata have the highest PD (6.0 ± 2.4 plants·m–2, mean
value), followed by C. capitatus (2.1 ± 4.7 plants·m–2,
mean value), by S. colorata and A. maritima (0.4 ± 0.1
plants·m–2, mean value) and by E. spinosa, E. maritimum,
M. marina, P. maritimum and C. soldanella (lower than
0.2 plants·m–2). E. farctus and A. arenaria are rhizoma-
tous species, with this last being the most important
sand-fixing species with positive effects on sand stability
[18,34,42] and the mycorrhizal symbiosis playing an im-
portant role in the growth [43,44].
The results underline the larger species presence along
the gradient from the water-edge toward the inland in P
compared to O where, on the contrary, plants exclusively
colonize the inner areas due to the strong human distur-
bance which causes the fore-dune to become flat. More-
over, P2, characterised by a relatively lower disturbance
than P1, has a 72% higher PD and a species distribution
over a longer strip from water-edge toward the inland (53
and 73 m in P1 and P2, respectively). The study under-
lines the ability of the considered sand dune species to
colonize the inner patch where microclimate and soil
conditions are more favourable (by a 56% lower wind
action and 12% higher SOM content, mean of the con-
sidered O and P plots) than the areas closer to the water-
edge. In response to the more favourable conditions, H
increases by 62% in the plots further from the water-
edge.
5. Conclusion
An increase in human impact in the near future, along
with global change, could act on sand dune species
changing their tolerance to stress factors. A management
plan needs to restore the most damaged dune areas and
actively prevent further environmental impacts. This
could be accomplished by developing and implementing
strategies which reconcile demands for human recreation
with conservation that is within the ecological carrying
capacity of coastal dunes [45]. Vegetation is an important
controlling factor for dune morphology [46]. An efficient
conservative management would consist of a temporary
protection of already degraded areas [2]. A combination
of a large variety of driving forces might suggest an un-
surmountable complexity. In fact every dune site has its
own history and management policy which should in-
corporate this [22]. Moreover, the maintenance of coastal
areas depends on the maintenance of native species [47].
Our results give information on the biodiversity of the
Tyrrhenian coast including a natural protected area. The
presence of the most important autoctonous sand dune
species (on an average, 15, 15, 15 and 16 autoctonous
species grow at O1, O2, P1 and P2, respectively) can pro-
vide information for restoring the perturbed dune areas
when preparing management strategies. In particular, A.
arenaria could have a positive effect on sand dune stabi-
lization by contributing to plant colonization under fa-
vourable conditions [48]. It must be emphasized that
species diversity and recovery capacity depend mostly on
the undisturbed sand deposits in the foredunes by the
limitation of human trampling and use of mechanical
means and infrastructure development. This could favor
sand deposits and consequently the species shift from the
inland toward the water-edge, thus maintaining the
coastal areas and their ecosystem services.
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