Vegetation of Thumamah Nature Park: a managed arid land site in Saudi Arabia

Thumamah Nature Park is located at about

100 km north of Arriyadh (Saudi Arabia), having an area

of 170 km2. The Park was established since 30 years ago.

The aim of this study is to analyze the vegetation structure

in relation to the environmental factors in different habitat

types. The phenological activities around the year of the 20

dominant species were monitored. 119 species were identified,

of which 51 (43 %) annuals and 68 (57 %) perennials

after 30 years of exclusive human impact. The

Saharo-Arabian component species were the highest

among the monoregional species (64 %) in most life forms,

while the Sahelien-Somali Masai attained the highest

among the biregionals (46 %). The TWINSPAN, DCA and

CCA analyses separated seven vegetation groups. The first

two groups were dominated by psammophytic species,

which occupy the lower sandy plain as shown in group I

with Rhanterium epapposum–Rhazya stricta and group II

with Pennisetum divisum–Haloxylon salicornicum. The

escarpment habitat was characterized by three groups, viz.,

group III with Acacia gerrardii–Panicum turgidum, group

IV with Panicum turgidum and group V with Acacia ehrenbergiana–

Lasiurus scindicus. Vegetation in the upland

plateau was represented by the remaining two groups;

group VI with Helianthemum lippii and group VII with

Helianthemum kahiricum. The environmental variables

that affect the species distribution and diversity in the park

include the altitude, soil texture, pH, EC, Ca, Mg and Mn.

The increased plant species richness, turnover, evenness

and cover were mostly due to the increase of the herbaceous

species. Plant populations showed interspecific

variations in their relative timing of phenological phases

with reproductive activity period ranged between 3 and

6 months with unimodal flowering peak. Three floweringfruiting

activities were recorded during late winter–spring,

summer and late autumn–early winter. In an attempt to

explain the vegetation dynamics after 30 years conservation,

the progressive succession varied among the different

habitat types, including the lower sandy sites, the escarpment

and the upland rocky habitats, which reflect the

relationship between altitude, edaphic factors and the type

of vegetation units in each habitat type after exclusion of

the human impact.

Mohamed Abdel Raouf Mousa Elsheikh

Vegetation of Thumamah Nature Park: a managed arid land site in Saudi Arabia

A., El-Sheikh, M. . 2013