remained in the central area with a slight movement toward the left, indicating the
increased presence of Typha. The border site quadrats dominated by Echinochloa
and Sagittaria (top center) changed to an area similar to the control area dominated
by native species.
16.4 Discussion
16.4.1 Invasive Species Removal
This study showed that removing the topsoil (in higher ground) up to 30–40 cm
and continuous flooding for 16 months decreased significantly the dominance of
Echinochloa and increased the dominance of native wetland plant species. López
Rosas (2007) experimentally exposed Echinochloa, Sagittaria, and Typha to
prolonged inundation and at the end of the experiment the biomass was lower for
Echinochloa compared with the native species (Sagittaria and Typha). The
opposite trend was recorded when shorter flooding periods were applied to the
same species. In this study, modifying the hydroperiod by flooding the area for
16 months after cutting the exotic grass prevented it from re-sprouting. Also, the
prolonged flooding helped native species that are more tolerant to inundation to recolonize the area successfully. However, long-term monitoring is needed, for
instance, 2009 was a relatively dry year that induced the exotic grass re-sprouting
in some favorable areas, considering the grass requirements. Shading the area
(50–60 %) was also useful as there were patches of native species interspersed
with the exotic species. Shading in controlled experiments (50 %), has been
documented to be an efficient mechanism for decreasing the invader’s biomass
(López Rosas 2007).
Another species that had to be removed from the site was D. brownei, which is
a native shrub/climber species that may be dominant in disturbed sites and covers
isolated or wetland edge trees, also forming dense, spiny thickets. Dalbergia has
been observed to increase its cover in the Reserve Cienaga del Fuerte, north of
Veracruz, after hurricanes Dean and Lorenzo in 2007. There is no published
information about the ecological response of this species to anthropogenic
b Fig. 16.5 Principal components analysis (PCA) ordination of quadrats in five wetland areas and
the RIVs of plant species in March 2007 (Time 0) and April 2010 (Time 36): a significant abiotic
vectors were water level (r = -0.67) and Eh (r = 0.64), where the angle and length of vectors
indicate the direction and strength of the relationships between abiotic factors and ordination
scores. b Succession vectors that indicate the change in species composition of each wetland zone
16 Interdune Wetland Restoration
265
increased presence of Typha. The border site quadrats dominated by Echinochloa
and Sagittaria (top center) changed to an area similar to the control area dominated
by native species.
16.4 Discussion
16.4.1 Invasive Species Removal
This study showed that removing the topsoil (in higher ground) up to 30–40 cm
and continuous flooding for 16 months decreased significantly the dominance of
Echinochloa and increased the dominance of native wetland plant species. López
Rosas (2007) experimentally exposed Echinochloa, Sagittaria, and Typha to
prolonged inundation and at the end of the experiment the biomass was lower for
Echinochloa compared with the native species (Sagittaria and Typha). The
opposite trend was recorded when shorter flooding periods were applied to the
same species. In this study, modifying the hydroperiod by flooding the area for
16 months after cutting the exotic grass prevented it from re-sprouting. Also, the
prolonged flooding helped native species that are more tolerant to inundation to recolonize the area successfully. However, long-term monitoring is needed, for
instance, 2009 was a relatively dry year that induced the exotic grass re-sprouting
in some favorable areas, considering the grass requirements. Shading the area
(50–60 %) was also useful as there were patches of native species interspersed
with the exotic species. Shading in controlled experiments (50 %), has been
documented to be an efficient mechanism for decreasing the invader’s biomass
(López Rosas 2007).
Another species that had to be removed from the site was D. brownei, which is
a native shrub/climber species that may be dominant in disturbed sites and covers
isolated or wetland edge trees, also forming dense, spiny thickets. Dalbergia has
been observed to increase its cover in the Reserve Cienaga del Fuerte, north of
Veracruz, after hurricanes Dean and Lorenzo in 2007. There is no published
information about the ecological response of this species to anthropogenic
b Fig. 16.5 Principal components analysis (PCA) ordination of quadrats in five wetland areas and
the RIVs of plant species in March 2007 (Time 0) and April 2010 (Time 36): a significant abiotic
vectors were water level (r = -0.67) and Eh (r = 0.64), where the angle and length of vectors
indicate the direction and strength of the relationships between abiotic factors and ordination
scores. b Succession vectors that indicate the change in species composition of each wetland zone
16 Interdune Wetland Restoration
265