Specific structure of primordial forests in the Middle East and North Africa: Shaping landscapes to maximize functionality of rain-cloud formation

Specific structure of primordial forests in the Middle East and North Africa: Shaping landscapes to maximize functionality of rain-cloud formation

Haruka Yoshimura, Ph.D.

Fig. 1 Normalization of regional hydrological cycle (rain-cloud formation) integrated with urban-heat-island mitigation in urban planning and management: Garden like ancient lush woods. To ensure rain-cloud formation, high LAI vegetation structure should be incorporated into urban areas to form continuous geographical distribution. The traditional design principal of Japanese landscape garden is to create an atmosphere of “deep ancient forests and mysterious torrent of valleys under tree shades,” to mitigate microclimate around building and in building, in a limited space, rapidly. Tree species of the ancient temperate forests of the “Epic of Gilgamesh” are almost all gone in the Middle East and North Africa. However, some of tree and plant genera of the primeval forests survive in both Eurasian and African continents. As freshwater is a non-substitutable resource for human life and food production, new paradigms in total land governance are urgently required. (References of urban-heat-island mitigation: http://harukanoor2.blogspot.jp/)

Primeval forests for wetter climate control

Prior to humanization of landscape, primeval forests thickly covered the land in the Middle East and North Africa.

The “Epic of Gilgamesh” vividly describes the green mountains covered with deep primeval cedar forests, where the “tall cedars raised aloft their luxuriance and cast a delightful shade,” in the lower reaches of Tigris-Euphrates River Basin (in present-day Iraq, vicinity of Uruk; 31°19´N, 45°38´E), around 5, 000 years ago. During the reign of Pharaoh Snefru dated around 2,600 B.C., an ancient Egyptian text known as the “Palermo Stone” mentions that forty ships filled with cedar wood arrived from Lebanon to Egypt for construction of a ship of a hundred cubits (about 50 m or about 170 ft.) in length and to make the doors of a palace. At that time, cedar wood resources on Mount Lebanon (34°18´N, 36°07´E), the chain of mountains extending from Turkey into Palestine, must have looked inexhaustible. Cedar wood had been a staple of the Phoenician economy for 3,000 years, from the time of the Pharaoh Snefru of the Old Kingdom of Egypt (ca. 2600 B.C.) until the reign of Emperor Hadrian (A.D. 117–138) of the Roman Empire (Mikesell 1969; Markoe 2006).

Julius Caesar (100–44 B.C.) in Rome was eager to exploit timber from the vast expanse of forests of Mount Atlas that sloped toward Africa, where the deep primeval forests that remained must have appeared unchanged since the world began (Perlin 2005). Today the so-called North Western Sahara Basin, which extends over much of Algeria, Libya and Tunisia, is a hyper arid region.

When the Portuguese first set foot on the island of Madeira (32°39´N, 16°54´W) in 1420, about 520 km (323 miles) west of the African coast, it was so thickly wooded by cedars and other species that they named it “isola de Madeira,” or “island of timber.” An early visitor of a Portuguese navigator Diogo Gomes (1420–1500) mentioned that the island was so well forested that he “could not see what was on the ground because it was completely covered by trees” (Perlin 2005).

The principal groundwater aquifers in the Middle East and North Africa were most recently recharged during Late Pleistocene and Early Holocene when the climate of the area was much wetter (Scanlon et al. 2006; Edmunds 2009). At that time, the active recharge to the aquifers was maintained by sufficient surface water of massive lakes and river systems along with the fairly deep surviving forests covering vast geographical areas in the Middle East and North Africa. Sufficient surface water supply originated with sufficient rainfall (precipitation).

The deep primeval forests covering these vast geographical areas played a crucial part in occurrence of rainfall (precipitation) via rain-cloud formation by the interaction between abundant moisture released active transpiration of the forests and evaporated water from the oceans, seas, lakes and rivers (http://harukanoor4.blogspot.jp/2016/). Effectively, the deep primeval forests have evolved in a way to maximize the function of rain-cloud formation over a period of 145 million years. 

Acknowledging that freshwater is a non-substitutable resource for food production and human life, an intrinsic solution (shaping landscapes for returning precipitation by restoring interaction between the atmosphere and terrestrial ecosystems) should be implemented (http://harukanoor4.blogspot.jp/). New paradigms in land planning and management, including urban planning and management, with strategic vision on water governance are urgently required (Fig. 1). Understanding of the species composition and forest structure of the primeval forests is essential to guide the restoration of terrestrial biome to maximize its functionality of regional hydrological cycle.

Evolution of temperate forests in the Northern Hemisphere

During the Jurassic Period of the Mesozoic Era, the “Age of Dinosaurs,” the Earth was covered with non-flowering plants such as ferns, horsetails, and Gymnosperms (seed-producing non-flowering plants). Jurassic Gymnosperms included seed-bearing trees: Cycas, Ginkgo and conifers such as yew (Taxus), the monkey puzzle tree (Araucaria), and cypress (Cupressus). The rapid diversification of angiosperms (flowering plants) in the early Cretaceous led to fundamental changes of terrestrial landscapes to angiosperm-dominated ecosystems of the Cenozoic Era (e.g., Crane et al. 1995).

Continental Drift (the movement of the continental plates) is closely tied to the global distribution of the tree and plant genera. In the Jurassic, the supercontinent Pangaea broke up into the supercontinents Laurasia (North America and Eurasia) and Gondwana (Africa, South America, India, New Zealand, Madagascar, Australia and Antarctica). In the late Cretaceous, when angiosperms had already achieved widespread dominance, Laurasia split into North America and Eurasia. Therefore, temperate forests in the Northern Hemisphere show similarity between North America and Eurasia, composed of common flowering tree genera such as oak (Quercus), beech (Fagus), hornbeam (Carpinus), birch (Betula), alder (Alnus), hackberries (Celtis) and maple (Acer). Tropical upland forests are forests above 800 m in the tropical zone. These temperate tree genera are also distributed in tropical upland forests in North America and East Asia, occasionally crossing the equator in the Southern Hemisphere. Fir (Abies), A genus of Eurasian conifer most closely related to the genus Cedrus (cedar), distributes in the temperate zone and the tropical uplands in North America and East Asia, mixed with the flowering tree genera. As most temperate forests in North America and Eurasia have been cleared by human activity for agriculture or human settlement, only scattered remnants of original forests remain.

The Cenozoic Era is referred as the “Age of Mammals” because mammals rose to dominance with the Cretaceous-Paleogene extinction event that wiped out remaining non-avian dinosaurs. Rapid diversification of angiosperms and slow diversification of gymnosperms continued and a mostly continuously distributed angiosperm-dominated forest formed in the Northern Hemisphere during the Tertiary Period of the Cenozoic Era. Human evolution began in the Quaternary Period of the Cenozoic Era.

During the long formation period of the widespread angiosperm-dominated forests in the Tertiary, Africa and Arabia (both split from Gondwana) lay so close to Eurasia that Eurasian temperate tree and plant genera dispersed over North Africa and the Arabian Peninsula. In the late Cretaceous, Africa and Arabia was moved northward to meet Europe and then collided with Eurasia in Turkish-Arabian region from the Eocene to the Oligocene (35–30 million years ago) in the Tertiary time (Jolivet 2000). Subsequently, Eurasian temperate tree and plant genera spread southward into the temperate zone and the tropical uplands in North Africa and the Arabian Peninsula, the same as in North America and East Asia. Conversely, the southern elements originated on Gondwana were dispersed northward into the warm temperate zone of Eurasia.

(The Indian subcontinent collided with the Eurasian plate about 50–55 million years ago, after long drifting in the Indian Ocean. Species composition of the Indian forests is different from the Eurasian primeval forests, as tree and plant species (genera) evolved in isolation.)

The primordial forests in the Middle East and North Africa

Although historical records show that luxuriant forests once covered the Middle East and North Africa, today only trees, shrubs and plants that have adapted to the arid conditions survive in the arid areas in the Middle East and North Africa. As the split between African plate and Arabian plate started in the Eocene in the Tertiary time, African elements of the flora are common to the flora of the Arabian deserts: tree genera such as Balanites (Zygophyllaceae) and Maerua (Capparaceae); herbaceous genera such as Moltkiopsis (Boraginaceae).

At the maximum development of the temperate forest biome during the Tertiary, the terrestrial ecosystems, composed of Eurasian temperate tree genera associated with African elements originated on Gondwana, appear to have been widespread in the temperate zone and the tropical uplands in the Middle East and North Africa.

Recent research of fossil pollen data (Nascimento et al. 2009) shows that the temperate forest biome was once widespread throughout Europe, North Africa and the Arabian Peninsula. Fossil pollen data from La Laguna (Tenerife; 28°30´N, 16°19´W) in Canary Islands, located 100 km (62 mi) from the African coast, indicates that two Eurasian flowering tree taxa, oak (Quercus) and hornbeam (Carpinus) appear to have been significant components from 4,700 to 2,000 years ago, which are now extinct on the Canary Islands. Based on the recent research, the Eurasian flowering tree taxa such as oak (Quercus), beech (Fagus), hornbeam (Carpinus), hackberries (Celtis) and maple (Acer) mixed with Eurasian coniferous tree genera such as cedar (Cedrus) possibly spread over the temperate zone and the tropical uplands in North Africa and the Arabian Peninsula.

Fig. 2 Primordial cedar forest: Angiosperm-dominated forest mixed with coniferous trees such as cedar as a canopy component. Prior human disturbance, deep forests, composed of Eurasian temperate tree genera such as oak (Quercus) and maple (Acer) associated with African elements (originated on Gondwana) such as Phoenix, dragon tree (Dracaena) and Vachellia (Acacia), were densely covered in the temperate zone and the tropical uplands in the Middle East and North Africa. Terrestrial biomes composed of biodiversity have evolved to maximize photosynthesis forming tall canopies and highly stratified foliage structure.

Species composition and forest structure of the primordial forests in the Middle East. In the remnant cedar forests of Lebanon (on the Arabian Plate), Beals (1965) indicates that the diverse Eurasian temperate tree genera such as oak (Quercus) and maple (Acer) are mixed with cedar (Cedrus libani). Prior human disturbance between around 12,000 and 10,000 years ago, pollen records from Lebanon indicates that the primordial cedar forests were composed of Eurasian temperate tree genera associated with African elements. Pollen data from the Aammiq wetland [foothill of Mount Lebanon; 33°46´N, 35°46´E, 865 m above sea level (asl.)] and from the Chamsine/Anjar wetlands (foothills of Anti-Lebanon Mountain; 33°44´N, 35°57´E, 856 m asl.) indicate that the primordial cedar forests were composed of Eurasian flowering tree genera such as oak (Quercus), maple (Acer), willow (Salix), chestnut (Castanea) and walnut (Juglans) mixed with Eurasian coniferous trees genera cedar (Cedrus libani) and pine (Pinus), associated with African elements such as Pistacia (Hajar et al. 2010). The structures of both the remnant cedar forests and the primordial cedar forests during late Pleistocene show a typical Eurasian temperate forest, angiosperm-dominated forest mixed with coniferous trees as a canopy component (Fig. 2).

Until around 5000 years ago, the angiosperm-dominated forest mixed with cedar remained intact in the downstream regions of the Tigris-Euphrates River Basin (on the Arabian Plate), as the Epic of Gilgamesh suggests.

The Angiosperm-dominated forests mixed with cedar were possibly widespread over the temperate zone and the tropical uplands in the Arabian Peninsula.

Occurrence of fossil pollen of Eurasian temperate tree genera, such as oak (Quercus), birch (Betula), alder (Alnus), beech (Fagus), pine (Pinus) and cedar (Cedrus) in the Arabian Peninsula, is generally interpreted as the effect of long-distance transportation. However, based on the current research that the temperate forest biome once widespread throughout the Arabian Peninsula, the presence of the fossil pollen of Eurasian temperate tree genera could be interpreted as the local presence.

Fossil pollen date form Pleistocene lake sediment in An Nafud in Saudi Arabia (27°51´N, 41°26´E, in temperate zone on the Arabian Plate) shows occurrence of Eurasian temperate tree genera, oak (Quercus), birch (Betula), alder (Alnus) and pine (Pinus) mixed with African elements (originated on Gondwana) such as Vachellia (considered members of genus Acacia until 2005), Maerua, Balanites and Hyphaene (Schulz and Whiney 1986). During 34,000 and 24,000 years ago, degraded remnant of the primeval temperate forests appears to have remained in the Arabian Peninsula. Fossil pollen of Holocene lake sediments from An Nafud and adjacent areas indicates that the landscape changed to semi-desert of grasses with some shrubs during 8,400 and 5,400 years ago. Occurrence of the fossil pollen, Vachellia (Acasia), Maerua (Capparaceae), Balanites (Zygophyllaceae) and doum palm (Hyphaene), similar to the present vegetation, indicates aridization of the oasis in the temperate zone of the Arabian Peninsula. Though, pine (Pinus), the Eurasian temperate coniferous tree genera tolerant to dry conditions, appears to have still survived at the time.

Fossil pollen data from early Holocene of Palaeolake Mundafan in southern Saudi Arabia, in the Rub,’ al-Khali, the ‘Empty Quarter,’ (18°32´N, 45°23´E, 860 m asl., in tropical upland on the Arabian Plate), where inhabited by hippopotamus (Crassard et al. 2013), shows occurrence of the Eurasian temperate tree genera of pine (Pinus) mixed with xerophytic (adapted to a dry environment) shrubs, Tamarix and Zizipus, about 8,000 years ago (Lézine et al. 2010). From around 8,000 years ago, disappearance of tree pollen types and increase of herbaceous plants such as Poaceae indicate gradual aridization at the time in the southern Arabian Peninsula (Lézine et al. 2010).

Fossil pollen data from early Holocene palaeolake sediment of Al-Hawa in Yemen (15°52´N, 46°52´E, 710 m asl., in tropical upland on the Arabian Plate) indicates occurrence of the Eurasian temperate tree genera: oak (Quercus), birch (Betula), beech (Fagus) and cedar (Cedrus), mixed with African elements: Vachellia (Acacia), Dipterygium (Capparidaceae) and Tribulus (Zygophyllaceae) (Lézine et al. 1998). From 8,700 to 7,800 years ago, remnant of primordial cedar forests appears to have survived in the tropical upland of the Arabian Peninsula.

The presence of the fossil pollen of Eurasian temperate tree genera strongly suggests that the ancient deep forests, composed of the Eurasian temperate tree genera associated with African elements, were extended in tropical uplands on the Arabian Peninsula, at the maximum development of the temperate forest biome during the Tertiary.

Species composition and forest structure of the primordial forests in North Africa. In North Africa, fragmented angiosperm-dominated forest mixed with coniferous trees such as cedar (Atlas cedar, Cedrus atlantica) survives in the Atlas Mountains. In remnant forests of the Atlas Mountains, diverse Eurasian temperate flowering tree genera such as oak (Quercus), birch (Betula), maple (Acer), willow (Salix) and chestnut (Castanea) are mixed with conifers such as Atlas cedar (Cedrus atlantica) and fir (Abies) as the dominant canopy component.

Pollen and plant microfossil records show that the Sahara in the present-day desert was either steppe, at low elevation, or temperate xerophytic woods/scrub, or even warm mixed forest in the Saharan mountains around 6,000 years ago (Jolly et al. 1998).

Fossil pollen data from La Laguna (Tenerife, Canary Islands; 28°30´N, 16°19´W) shows occurrence of two Eurasian temperate flowering tree genera, oak (Quercus) and hornbeam (Carpinus) associated with African elements such as Phoenix and dragon tree (Dracaena), from 4,700 to 2,000 years ago (Nascimento et al. 2009). Based on the recent research, distribution of the Eurasian temperate tree genera appears to have been spread over the temperate zone in North Africa.

Fossil pollen data from tropical upland in Africa indicates the presence of the Eurasian temperate flowering tree genera during the late Pleistocene and Holocene period. Fossil pollen data from Lake Victoria in Uganda (0°18´N, 33°20´E, 1,134 m asl., in tropical upland) indicates occurrence of Eurasian temperate flowering tree genera hackberries (Celtis) associated with Podocarpus (a genus of conifers endemic to the ancient supercontinent Gondwana), from 13,000 years ago to present (Kendall 1969). Similarly, fossil record from Ahakagyezi Swamp in southwest Uganda (1°5´S, 29°54´E, 2,100 m asl., in tropical upland) shows occurrence of Eurasian temperate tree genera hackberries (Celtis) associated with Podocarpus, during the late Pleistocene to Holocene (Taylor 1993). Podocarpus pollen dramatically increased around 4,000 years ago elsewhere in eastern Africa, e.g., in the Lake Victoria in Uganda (Kendall 1969) and in the Ahakagyazi Swamp in Uganda (Taylor 1993). In Eastern Africa, forests and woodlands had been cleared for cultivation beyond 4,800 years ago. As Podocarpus favours drier sites within moist montane forests, the Podocarpus expansion suggests onset of drier climate due to decreased rainfall (Hamilton et al. 1986). Drought tolerant hackberries (Celtis) increased simultaneously with the Podocarpus expansion. A long history of forest clearance and consequent soil erosion in Africa have significantly transformed the regional hydrological cycle.

At the maximum development of the temperate forest biome during the Tertiary, distribution of the Eurasian temperate tree genera appears to have been widespread over the tropical uplands in North Africa.

The island of Madeira (32°39´N, 16°54´W), about 520 km (323 miles) west of the African coast, was thickly wooded by cedars and other species when the Portuguese first set foot in 1420. An early chronicler commented that “the trees growing on Madeira attained such height they seemed to touch the sky.”

Prior human disturbance, the tall and thick primeval forests such as in the island of Madeira in 1420, composed of Eurasian temperate tree genera associated with African elements (originated on Gondwana) such as Phoenix, dragon tree (Dracaena) and Vachellia (Acacia), were densely covered in the temperate zone and the tropical uplands in North Africa.

Shaping landscapes to maximize its functionality of rain-cloud formation

Evolution of high LAI vegetation

More than 3 billon years ago, early life on Earth, photosynthetic bacteria, developed the capacity to efficiently capture solar energy and use it to power the synthesis of organic molecules. The energy of solar radiation has been harnessed through the process of photosynthesis. About 475 million years ago, first land plants, which descended from green algae (aquatic photosynthetic organisms), evolved. They were unable to grow tall as lacking vascular structure (stems and roots). About 425 million years ago, a new type of land plant, vascular plants, appeared in the Silurian Period of the Paleozoic Era. The vascular plants are able to grow tall canopies to capture more sunlight.

The terrestrial ecosystems seem to have evolved to maximize the process of photosynthesis via forming tall canopies and highly stratified foliage structure to capture more sunlight effectively. To grow tall canopies and to develop stratified foliage structure for capturing solar radiation effectively, terrestrial ecosystems appear to have evolved an integrated biome composed of a mixture of conifers and flowering tree genera with understory vegetation of diverse vascular plants (flowering plants, conifers, ferns, horsetails and clubmosses) (Fig. 2).

Leaf area index (LAI, the ratio of leaf area per unit ground area) is a powerful parameter of vegetation productivity, as primary production (estimated amount of organic compounds fixed atmospheric carbon dioxide via photosynthesis) is closely related to light interception. A high LAI of over 8 is the level found in mature forests such as temperate broad-leaved evergreen forests and tropical rain forests (Odum 1971; Whittaker and Likens 1973; Chapin 2003).

Crucial role of high LAI vegetation in regional hydrological cycle

Water is a renewable resource in the sense that evaporated water returns via rainfall (precipitation) by the interaction between transpiration of the terrestrial biomes and evaporated water from the oceans, seas, lakes and rivers (http://harukanoor4.blogspot.jp/). Photosynthesis is directly related to transpiration under sufficient water supply conditions (e.g., Running and Coughlan 1988), as the process of photosynthesis synchronizes with transpiration. Primordial forests, an extreme system of the most highly evolved high LAI vegetation, developed the capacity to provide the most abundant supply of moisture via active transpiration, which in turn contribute to cloud-formation.

 

Land governance incorporated the structure of the primordial forests in the Middle East and North Africa 

Today, being accustomed to cultivated fields and large cities, it is difficult for us to imagine the density and height of the high LAI terrestrial biomes composed of diverse trees and plants. The “Epic of Gilgamesh” describes that mountains in the lower reaches of Tigris-Euphrates River Basin were covered deep forests “where the foliage was so dense that the sun could barely shine through,” as highly-stratified canopy foliage structure of the primordial cedar forests, characterized by high LAI values, effectively intercept solar radiation. To develop tall terrestrial biomes composed of biodiversity, it takes a long time of about 425 million years from the first landing of plants. The primordial forests in the Middle East and North Africa were looked like the Medieval Period forests in the island of Madeira, which was so thickly wooded that “the trees growing on the forests attained such height they seemed to touch the sky.”

The water resources upon which people depend came substantially from the regional hydrological cycle that evaporated water returns via rainfall (precipitation) by the interaction between terrestrial biomes and evaporated water from the oceans, seas, lakes and rivers. The land in the Middle East and North Africa has experienced decline in this function. To avoid a catastrophic risk that stems from a spreading water shortage and ever growing food insecurity, new paradigms in land planning and management incorporating restoration of high LAI vegetation with the strategic vision on restoring regional hydrological cycle are urgently needed. 

For intelligent choice of Homo sapiens

Whittaker and Likens (1973) stress the importance of high LAI vegetation of forests: “Stability of surface is again critical. Given stable surfaces, land plants have so evolved that long-lived plants are dominant. These plants use the biomass that is the accumulated profit of net productivity for their extensive root and aboveground structures. These structures are in turn part of the basis of high productivity through their support of photosynthetic surfaces and contribution to the pattern of nutrient use and retention.” 

Ancient lore in the Middle East and North Africa says that this area will someday “be green again.” However, natural restoration of vegetation does not occur automatically, due to a long history of forest clearance, consequent widespread aridization and lack of biogeographical access to the tree and plant species once ubiquitous in the terrestrial ecosystems.

Primordial forests composed of biodiversity, extreme system of the most highly evolved of high LAI vegetation, developed a most advanced system on Earth contribute to cloud-formation. Therefore, restoration of high LAI vegetation mimic the natural system requires multiple mixed planting with canopy forming tall trees, mid-story small trees/shrubs, and diverse under-story vascular plants (e.g., Fig.1). Large numbers of tree and plant species once ubiquitous in the terrestrial ecosystems are extinct in the Middle East and North Africa. In order to shape landscapes with high LAI vegetation structures, tree and plant genera from Europe, Asia (including Japan) and Africa will substitute for the extinct genera in the Middle East and North Africa. 

Because of the critical feature that there is largely no substitute for freshwater for human life and food security, shaping water landscapes along with deep primordial forests is essential for intelligent choice for sustainable future of humans. Today many lands all around the world have declined contribution to the regional hydrological cycle that evaporated water returns via rainfall (precipitation) by the interaction between terrestrial biomes and evaporated water from the oceans, seas, lakes and rivers, as most primordial forests have been cleared. As consequent water shortage and growing food insecurity pose the challenge for our future, the total land governance incorporated the high LAI vegetation structures is urgently required around the world. The primordial forests have endemic structures (e.g., the Pacific Northwest of North America, Waring and Franklin 1979). Appropriate for the biogeographical history, latitude, altitude, site aspect and for our cultures, we should shape continuous lush landscapes over vast geographical areas with maximize use of our ability to transform nature (see explanation in http://harukanoor4.blogspot.jp/2016/).

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