Where is welwitschia found

Its natural range extends over an area of , square km along the southwestern coast of Africa from the Kuiseb River the Tropic of Capricorn in central Namibia to the Bentiaba River in southern Angola. Its preferred habitat appears to be hyper-arid gravel plains or gypsum-rich soils.

Below are five best locations in Namibia to see a variety of wild Welwitschia mirabilis plants growing within distinct, but equally natural habitats numbered as on the map above. It is the most popular and widely advertised site in the Central Namib Desert for viewing Welwitschia plants. Situated between the Khan and Swakop rivers, it is a part of the Namib-Naukluft Park and has an easy access both from Swakopmund in the west and Windhoek in the east.

Typical landscape of the Welwitschia Plains. A permit , which can be obtained in Swakopmund, is required to access the Welwitschia Plains. With this permit, you will also receive a hand-drawn map of the Namib-Naukluft Park containing the small section dedicated to the Welwitschia Drive.

The round trip is km and takes about hours to tour with stops. It is an arid and barren place, but the area by the Swakop river provides some shade and is equipped with picnic tables and even campsites for overnight stays if desired. Look for 13 labelled stone beacons.

The Swakopmund location along the Welwitschia Drive boasts the oldest known plant colony, some of which are of remarkable size. The two largest Welwitschias both female plants in existence are growing here. These are also the oldest living Welwitschia plants , with an age of years as estimated by carbon dating. The latter plant occupies an area 9. Local mining activities resulted in excavation of some old Welwitschia plants in the area.

The leaves of the mature welwitschia usually grow about 8 to 15 cm per year. It has been recorded that some have measured 1. History The welwitschia plant is eponymous to its discoverer — Friedrich Welwitsch. Welwitsch was an Austrian botanist who first researched and recorded the plant in in the Namib Desert in the southern regions of Angola. Dr Friedrich Welwitsch Dr. Friedrich Welwitsch was born in Austria in He was a theatre critic for a while, and then fled to Portugal where he worked as a plant collector.

Many years later, the Portuguese government dispatched him to Angola where he made more than collections during his 12 years in the country. Some of his discoveries were entirely unknown and new to science then and his collections were valuable for its information and research. The stem shows a continuous transition into a broad taproot that rapidly gets thinner with depth within the first meter.

Further away from the stem, one to four smaller roots of only 1—3 cm diameter typically spread horizontally but also exploit deeper soil layers. Kutschera et al. After germination, young plants rapidly develop a taproot. Several authors 17 , 20 have interpreted Welwitschia as a phreatophyte based on the preferred habitat adjacent to drainage lines and the pronounced taproot formation.

However, Bornman 21 reported that roots near the Brandberg do not extend deeper than 3 m. A recent study 13 details the root architecture and water uptake of plants near the Swakop River. No roots deeper than cm were observed, and the majority exploited rainwater within a gypsum crust and deeper petrocalcitic horizons.

Only a small percentage showed upward growth, indicating uptake of a smaller amount of topsoil water. Similarly, a study at Gobabeb 22 did not show an influence of fog on leaf growth rate or germination.

Based on current knowledge of the range and phylogenetic position, we seek to establish a new and complete biogeographical record. Additionally, we explore the genetic similarities among seventeen range-wide populations using the first developed SSR markers for Welwitschia. It is remarkable that beyond the foci of the aforementioned studies and around other publications 22 , there has been no attempt to capture the environmental niche of Welwitschia within the whole range but see 23 for some partial range elements.

Therefore, our objectives are to 1 investigate genetic differentiation among the sample records from all range fragments in Angola and Namibia to determine whether they support the existence of two subspecies; 2 examine environmental differences among the geographic fragments; and 3 discuss the results that most obviously characterize the ecological niche of Welwitschia.

Our systematic mapping results allow for drawing a new map of the range of Welwitschia Fig. A total of Welwitschia locations is derived from own observations, while 87 locations were compiled from herbaria and published literature. The resulting confirmed locations are shown in Fig. We also mapped landscapes with a continuous presence of Welwitschia.

Based on the mapping, we could also group and name all the resulting range fragments Table 1. The broadest section in a W—E direction connects populations located just west of Khorixas at With the newly found locations, the area of distribution of the genus almost doubles in Angola. New northernmost, southernmost, and easternmost records have been made as well as new populations closer to the Atlantic coast than previously recorded.

We found a new northernmost record in Angola, north of Fael at Similarly, the southernmost record could be extended slightly to Disjunct distribution area of Welwitschia and its relation to annual rainfall. The black dots represent Welwitschia locations confirmed by or newly recorded during this project. Large populations with a quasi-continuous presence are shown in gray.

Isolated range fragments are named in yellow. White numbers and names designate the locations of populations sampled for SSR analysis. The isolation of range fragments is indicated by their distance in km. The white bar designates a major geographic gene-flow barrier; within Welwitschia , the broken lines designate geographic gene-flow barriers within subspecies.

The black line marks the border between Angola and Namibia. The blue lines are isohyets of mean annual rainfall in mm increments. The horizontal black line marks the border between Angola and Namibia. The white dots refer to all locality names mentioned in the text and tables.

The new northernmost record is nearest to the coast, 4. From N to S, the other large range fragments have the following minimum distances to the coast: The Welwitschia population farthest from the Atlantic coast km is situated just W of Khorixas at This is also the most humid site at just over mm mean annual precipitation MAP , compared to the majority of populations at less than mm MAP.

The biogeographical range of Welwitschia is strongly fragmented into spatially isolated, disjunct partial ranges in a linear spatial arrangement from north to south along the hyperarid to arid Namib Desert. The range fragments are presented in Fig.

In both countries, we found aggregates of two large range fragments separated by gaps smaller than 30 km; the two in Angola Tombua—Virei and Iona are km from the two in Namibia Etendeka and Messum.

In the space between them and in the extreme north and south of the whole range are additional small range fragments. The aggregate of the two Namibian range fragments, Etendeka and Messum, is larger in area, while the two Angolan range fragments, Tombua—Virei and Iona, contain the largest number of individual plants.

The high number of individuals strongly correlates to the very high plant density in Tombua—Virei and Iona. In our standard plots of m 2 we often counted more than plants: for example, in plot 36, In a first approximation, populations of the genus Welwitschia are viable within an arid niche defined by a MAP of less than mm; many fragments in parts receive less than mm, and the more southern range fragments less than 50 mm Fig.

At the arid extreme of the niche, the coastal Welwitschia records of the Messum fragment at Goboboseberge are just above 20 mm MAP. With regards to the rock types Table 2 , granite, basalt, limestone, sandstone, and mica schist play an important role in different range fragments.

Rocky plains with shallow leptosols and rocky or stony slopes—especially at the lower end of a slope, often in sandy patches below granite boulders or other larger rock surfaces—are also found in some places. Calcretes are found in most of the range fragments, while gypcretes play an important role in the western parts of the Messum and Khan—Swakop range fragments.

Concerning neighboring vegetation, Welwitschia mirabilis is most often associated with the following perennials in decreasing order of importance : Zygophyllum stapffii , Zygophyllum simplex , Arthraerua leubnitziae , Calicorema capitata , Petalidium variabile , Adenolobus pechuellii , and Commiphora wildii In contrast, Welwitschia mirabilis is obviously outcompeted by Acacia reficiens , Acacia mellifera , Acacia tortilis , Colophospermum mopane , and sometimes Salvadora persica , as can be deduced from the immediate disappearance of Welwitschia at the margin of stands of these woody species—for example, when approaching Virei or Khorixas from the west.

We conducted a principal component analysis PCA of 16 scaled bioclimatic variables from the WorldClim dataset and a set of 16 lithological units extracted from digitized geological maps of Angola and Namibia. The first two axes of the PCA already explain approximately The observed pattern clearly separates the Angolan and Namibian range fragments on the first two principal axes, while the transitional fragments Sanitatas, Ougams, Ganias are separated on the third axis see Supplementary Figure S1 online.

The first principal axis describes a warm—wet Angola versus cold—dry Namibia gradient, while the second axis reflects the gradient of climatic variability, in particular concerning temperature range. The third axis only represents 8. We also conducted a multivariate group test ANOSIM to verify statistical differences in bioclimatic composition among the fragments.

The R-statistic of 0. Finally, we conducted a Kruskal—Wallis test and Nemenyi post hoc test to analyze the differences among the range fragments in each environmental parameter Table 3.

The overall pattern supports the findings of the PCA. PCA of bioclimate and geology for all observed Welwitschia samples. Colors highlight the different range fragments. Lithology: aeolian 1 , basalt 2 , calcareous 3 , complex 5 , gneiss 6 , granite 7 , mica 8 , mudstone 9 , quartzite 10 , calcrete 11 , sandstone 12 , sand 13 , volcanic We used samples from 17 populations Fig.

At the largest spatial scale Fig. The split between the northern and southern subgroups is located in Namibia at Only one population of the southern subgroup Etendeka-7 shows a weak genetic relationship to the northern subgroup Fig. Looking deeper into the genetic structure of the two subgroups, we divided the sampling set according to the two gene pools, and we reanalyzed the northern and southern populations separately. The structure analysis of plants of the northern subgroup Fig.

Especially, the populations of the Kaoko range fragment Sanitatas This population is located in northern Namibia, where it is geographically separated by km from the large Iona range fragment in Angola. Most of the individuals of population 2 are assigned to the same gene pool Fig.

The populations 1, 3, and 4 are even more strongly assigned to combinations of three gene pools. These populations overlap significantly in ordination owing to smaller genetic distances between individuals Fig. The PCoA patterns of the southern taxon populations are shown in Fig. The large Etendeka range fragment with populations Etendeka-8 and Etendeka-9 is located in the center.

Closely attached are the more coastal populations Etendeka-6 and Etendeka-7 , and Messum, 11 and In contrast, populations Kuiseb and Kuiseb—17 of the Kuiseb range fragment cluster separately at the upper left corner of the PCoA, while populations Khans-Swakop to Khan-Swakop—15 of the Khan—Swakop range fragment are grouped separately at the upper right corner.

The structure analysis of the southern subgroup revealed a best K of four different gene pools. These are presented in Fig. The populations of the Khan—Swakop range fragment Khan-Swakop to 15 and Kuiseb range fragment Kuiseb and Kuiseb—17 in the south are assigned to one unique gene pool Fig. The Khan—Swakop and Kuiseb fragments are genetically and geographically well separated from the large central Etendeka—Messum aggregate with gap widths of 83 km and km, respectively.

In contrast, the gene pool of Ganias-7 is also found in the western parts of the large Etendeka range fragment. The extant Welwitschia mirabilis has developed considerable genetic diversity within the refuge. Our results support the existence of two well-separated taxa within Welwitschia , located in both the northern and southern parts of the total range, as proposed by 7. The gene-flow barrier is located in Namibia at The structure analysis Fig. This sharp discontinuity is in contrast to their moderate spatial isolation: the nearest range fragments are only 65 km away.

At Moreover, the first two principal axes of the PCA of 19 scaled bioclimatic variables and geological units indicate that the environmental conditions of the Sanitatas and Ougams range fragments are similar to the other Namibian range fragments Fig. On the third PCA axis, the Sanitatas range fragment is distinctive for having slightly less variability than most Namibian samples and a slightly cooler and drier climate than the Angolan samples. However, the location of the discontinuity coincides with an important biogeographical limitation, namely the southern boundary of the Kaokoveld desert ecoregion It should also be noted that this barrier is equidistant to the range fragments forming the largest aggregations by area in the north Iona and Tombua—Virei and south Etendeka and Messum.

It is possible that these major gene pools in the past were the only to survive and later expanded equally into the intermediate space. Further research is needed to explain this biogeographical boundary with regards to Welwitschia and other taxa.

Although these data clearly show geographic isolation, at present there is no evidence of reproductive isolation. Therefore, the two taxa are correctly regarded as subspecies of Welwitschia mirabilis , with ssp.

We found further genetic diversity within each of the two subspecies. The structure analyses identified up to three gene pools for individuals from both subspecies in the large central range fragments Fig. The round trip by car takes approximately four hours, allowing one to get out at each of the numbered beacons to explore the area.

The required permit, which allows entrance to the park as a whole, is obtainable from the Namibia Wildlife Resorts office in Swakopmund. If you decide to stay over in the park, there are many camping sites to choose from, including one at the Welwitschia trail. A camping permit can also be obtained from the office. How to get there: From Swakopmund follow the tarred road to Windhoek and then turn off onto the Khomas Hochland road signposted just beyond the Martin Luther steam engine.

Continue along this road, crossing the Swakop River, until you reach the entrance to the Namib Naukluft Park. After a short distance you will see the signpost at the start of the trail.

Turn left here. After a short while you will come across the first of the 13 numbered stone beacons that indicate places of particular interest. At a first glance it would seem that the Namib desert is a dry and barren region, but look again. The ground and stones are covered with a great variety of lichens.

They depend for their survival on the mist that moves in from the sea over the desert at night and in the morning. Take note of the lichens that look like black fragments of dead plant material. They lie loose on the surface and tend to collect in furrows. If placed in water they unfold and change colour.

Along the way two kinds of drought resistant shrubs are predominant: The Dollar bush, name given because of its coin-like round leaves, and the Ink bush, with its fine leaves and spindly appearance.

Both these kinds of plants are well adapted to an area which receives an average of less than 20 mm of rain a year, and then mostly in single downpours. Often there is no rain in the area at all for several years.

Here the tracks of an oxwagon trail, used decades ago, can still be seen where it leaves the present road. The route was called the "Baaiweg" as supplies were transported from the coast to the inland. These tracks are still visible today because the lichens that were destroyed by the routes are not yet fully reestablished. Lichens grow extremely slowly, less than 1 mm a year. It is therefore most important for the ecology in the area that travellers should keep to existing roads at all times.

The valleys of the Swakop river form a spectacular ''moon landscape''. It came into existence as the river cut through the softer surface deposits.

These soft materials were laid down some million years ago when the area's climate was more wet. In the background one can see the Rossing mountain. Because of the Namib's exceptional climate with its misty nights, the lichen fields here are more extensive than anywhere else in the world.