Impacts of Surviving and Dead Shrubs and Grasses on Floral Diversity and Community Structure of Sandy Dunes of the UAE (original) (raw)
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The Arab Gulf desert region is dominated by few shrubs and grasses, although mostly devoid of vegetation. The impact of both live and dead shrubs and grasses on plant diversity and community composition on sand dunes of the United Arab Emirates was assessed. Species richness, diversity indices (Simpson, ShannoneWiener, and Brillouin), and plant abundance were significantly greater under dead grasses than in the surrounding open areas. However, the opposite was true for live grasses. Dead and live shrubs did not differ significantly in species richness and abundance. The relative interaction index indicated that live nurse grasses inhibited 13 species and facilitated only one species, whereas dead grasses facilitated 13 species and did not inhibit any species. Live shrubs facilitated four species and inhibited two, but dead shrubs facilitated 10 species and inhibited none. Organic matter and most of the assessed soil nutrients were significantly higher under both shrubs and grasses than in the barren spaces in-between. The facilitative effect of dead grasses on soil characteristics was more obvious. The results support the feasibility of growing nurse shrubs and grasses to restore degraded arid desert environment.
During the period of Jun 2004 until Feb 2005 a study was carried out to assess and quantify the vegetation cover and plant community in the Dubai Desert Conservation Reserve (DDCR). This was done to provide baseline data that will serve as the preliminary basis for temporal comparison, provided that monitoring is a continuously ongoing activity in DDCR. An emphasis was placed on assessing the density, cover and diversity of the flora of DDCR and in addition an attempt is made to map the vegetation of DDCR. A total of 269 plots covering 1883000 m² were sampled over the DDCR and Al Maha Reserve (AMR). The sampling was done using plot sampling approach over the 2 main habitats; Gravel plains and Sand dunes. A standard of 10% coverage was maintained. In each plot several parameters were measured for each species; density, relative density, frequency, relative frequency, abundance, relative abundance and importance value. Diversity indices were used to quantitatively assess the diversity...
Arid Land Research and Management, 2019
Most of the sand dunes close to the Mediterranean coast of Egypt have been destroyed due to human pressures. The remaining dunes are under extreme threat due to unplanned development. This study aims to explore the floristic patterns and detect which drivers threaten their conservation status. Eighty-five random plots of 100 m 2 each along 12 transects perpendicular to the seashore in the northwestern coastal dunes were sampled. Classification of plots using plant cover percentage was carried out through agglomerative hierarchical clustering and principal coordinate analysis. Canonical correspondence analysis (CCA) and variance partitioning (VP) were used to define the drivers that influence the floristic patterns. Therophytes and chamaephytes represent 30% of each of the 113 vascular plant species recorded in the present study. Four clusters of plant species corresponding to four dune-types were identified: Ammophila arenaria-Ononis vaginalis in foredunes, Echinops spinosissimus-Launaea fragilis in embryonic dunes, Echinops spinosissimus-Allium erdelii in transitional and Echinops spinosissimus-Thymelaea hirsuta in stabilized dunes. Stabilized dunes showed the highest diversity (species richness H dune ¼ 1.37, evenness E dune ¼ 0.88) and rarity indices (R ¼ 0.52) as well as a steeper rarefaction curve. CCA disclosed that organic matter and CaCO 3 content, distance from the coastline, overcutting, trampling, and urbanization were correlated with the floristic patterns. VP showed that the examined variables justified for 53% of the variance in the floristic composition. Our results can be considered by managers to fulfill an appropriate conservation plan to preserve and manage the coastal dunes in arid regions.
Journal of Forest …, 2009
The present study analyses the effect of land use on the vegetation of some desert ecosystems in Abu Dhabi, United Arab Emirates (UAE). Three sites were selected to represent different types of land use, inside Umm Al-Banadeq forest, outside the forest and along Abu Dhabi-Al Ain Trucks Road. In total, fifty-two stands were examined; including a matrix of 14 species x 52 stands. Based on species cover data, stands were classified using TWINSPAN and ordinated using DCA. Four vegetation groups were generated at level three of classification. Zygophyllum mandavillei was dominant in most vegetation groups; Heliotropium bacciferum dominated vegetation groups inhabited the forest. Species richness, species turnover, relative evenness and relative concentration of dominance of forest vegetation groups were 2.8, 5.7, 0.7, and 2.0, respectively. The differences were attributed to both natural variability and forestry-induced changes, including change in land use, drainage and ploughing and shading by trees. Vegetation group inhabited Abu Dhabi-Al Ain Trucks Road, that were dominated by Haloxylon salicornicum and Zygophyllum mandavillei have high total cover (8.8 m per m-1). Most community and vegetation attributes were significantly higher inside the forest than outside. Human interventions and environmental factors affected species diversity and abundance of these communities.
An analysis of vegetation and species diversity patterns in sand dune and gravel desert ecosystem
Botanical Sciences, 2016
This study provides an analysis of vegetation and environmental relationships as well as diversity patterns in sand dunes and gravel desert plains of northern Badrud, Iran. A total of 63 species representing 49 genera and 15 families were recorded. The largest families were Asteraceae (22.2 %) and Chenopodiaceae (19.0 %). Therophytes (66.67 %) were the dominant life form. Chronological analysis showed 57.14 % Irano-Turani elements. Data from 60 1.5 × 2 m 2 quadrats, selected systematically randomized along three transects, were collected. Both two-way indicator species analysis (TWINSPAN) and cluster analysis using Ward's method resulted in the recognition of three communities: an Artemisia sieberi community in the center plain with a Shannon-Wiener diversity index of 0.3, a Stipagrostis plumosa-Schismus arabicus community on the lower sand dunes with a Shannon-Wiener diversity index of 0.7, and a Haloxylon ammodendron community on the higher sand dunes with a Shannon-Wiener diversity index of 0.2. Detrended correspondence analysis (DCA), non-metric multidimensional scaling (NMDS), and multi-response permutation procedure (MRPP), confirmed the separation of TWINSPAN groups as well as the heterogeneity of the Artemisia sieberi-Schismus arabicus community, suggesting a distinct group with Artemisia sieberi and Schismus arabicus as the dominant species. Vegetation environmental analysis by means of multivariate techniques of principal component analysis (PCA) and canonical correspondence analysis (CCA) indicated that very coarse gravel has a strong negative effect on diversity and a negative effect on species cover percentage. Bare ground showed a highly positive effect on diversity variables. Soil analysis suggests final seral stages of succession towards severe desertification.
Journal of Arid Environments, 1997
Dwarf shrubs play a predominant role in the natural vegetation cover of Kuwait, with the chenopod Haloxylon salicornicum widespread in northern parts of the country. A number of influences, largely anthropogenic in nature, have led to serious land degradation in many areas. The present study deals with species diversity and other floristic attributes of the ephemeral vegetation in a sand-depleted Haloxylon salicornicum community, contrasting the situation of miniature dunes formed at the base of shrubs with that of the interdune space. The importance of such dunes and their associated shrub cover as a protection against further land deterioration is examined.
Agriculture, 2021
Grazing is one of the most important land management activities worldwide, and cases of overgrazing increase erosion, land degradation, and plant invasion. The objective of this study was to assess the effect on individual species and species composition in response to groups of plants removals or grass seeding after four years of vegetation transformation in a microphyllous desert shrubland excluded from cattle grazing. Nine treatments involved (1) clearing of vegetation and seeding of Bouteloua curtipendula (BOCU), a native grass, (2) clearing and seeding of Chloris gayana (CHGA), an introduce grass from Africa, (3) clearing except for grasses (GRA), (4) clearing except for grasses and fodder shrubs (GRA-SHR), (5) free grazing by cattle (GRAZ), (6) clearing except fodder shrubs (SHR), (7) no modification (CON), (8) clearing of all plants (BARE), and (9) clearing except plants not eaten by cattle (UND). Treatments were replicated five times each in 10 m × 10 m experimental plots. P...
Effects of camel grazing on the ecology of small perennial plants in the Dubai (UAE) inland desert.
2005
Camel grazing is recognized as a primary cause of ecological degradation in the UAE. A study of perennial plant species o1m in height was conducted along a fence separating continuously camel grazed land from land in which camels had been replaced by oryx and gazelle species for 5 years (Al Maha). Vegetation regeneration in Al Maha in the absence of camels was considerable on all substrates (gravel, stable sand, and semi-stable sand) but was greatest on the gravel substratum, indicating that ecology in this habitat is most at risk. Observed regeneration was primarily through vegetative reproduction and growth of existing plants, showing that existing species can tolerate heavy grazing. Therefore, an equilibrium grazing model of continuous and reversible vegetation dynamics is most suitable for management of this ecological zone. Species richness was greater in Al Maha due to the greater number of plants, but biodiversity was unaffected. There was some evidence of localized dune stabilization within Al Maha due to increased vegetative cover. Further recovery of vegetation within Al Maha is discussed. This study highlights the need for reduced grazing pressure throughout the Dubai inland desert, and in particular on gravel substrata.
Changes in plant species composition of coastal dune habitats over a 20-year period
AoB plants, 2015
Coastal sandy ecosystems are increasingly being threatened by human pressure, causing loss of biodiversity, habitat degradation and landscape modifications. However, there are still very few detailed studies focusing on compositional changes in coastal dune plant communities over time. In this work, we investigated how coastal dune EU habitats (from pioneer annual beach communities to Mediterranean scrubs on the landward fixed dunes) have changed during the last twenty years. Using phytosociological relevés conducted in 1989-1990 and in 2010-2012, we investigated changes in floristic composition over time. We then compared plant cover and the proportion of ruderal, alien and habitat diagnostic species ("focal species") in the two periods. Finally, we used Ellenberg indicator values to define the "preferences" of the plant species for temperature and moisture. We found that only fore dune habitats showed significant differences in species cover between the two tim...