Forests Phenolic Compounds Instigate Cloud Precipitation

Background The wind shakes trees uttering their leaves generating heat within. Mechanosensing is a crucial process in regulating trees’ growth and development. Mechanical stresses generate internal and external signals in trees. The aim is to establish the myriad of communication signals between forests, their ecology, wind and the clouds.


Introduction
Mechanosensing is an important process contributing to the regulation of plant growth and development (Berlyn, 1961;Hamant, 2013). Mechanical stresses generate internal signals produced during tissue and cellular development (Ingber, 2005;Hamant et al., 2008) or via external signals from the ecosystem, particularly the wind (Moulia et al., 2011). A number of factors in uence mechanosensing, though some factors predominate in certain situations. It has been shown that trees display adaptation to the local wind environment. Like other plants, trees can enhance their endurance to transpirational ow by opening and closing their stomata. Wind is one of several factors that can interact virtually to affect stomatal function. Winds can alter leaf form and temperature, which means that the short-term outcomes of wind on photosynthesis are diverse and unpredictable (van Gardingen and Grace, 1991;Telewski, 1995).
The mechanics of plant responses to wind have been widely researched (de Langre, 2008). Much of the research focuses on tree pliability (Mayer, 1987;Kerzenmacher and Gardiner, 1998;Selier and Fourcaud, 2005;Rodriguez et al., 2012) or crop crown movement (Py et al., 2005(Py et al., , 2006Dupont and Gosselin, 2010). Wind has been found to in uence the time-averaged transformation settings and form of leaves via the mechanism of recon guration (Vogel, 1989;Gosselin et al., 2010;Tadrist et al., 2014). Regarding leaf sway, Roden (2003) patterned aspen leaf utter as a speci c recurrent rotation, and Niklas (1991) identi ed poplar leaf sway as a possible example of the conventional linked type of uttering (Tadrist et al., 2015). The uttering of leaves generates energy for plants and causes stress. Plants are highly sensitive to a range of effects, from signi cant to minor physical damage, and respond to mechanical stresses promptly or over longer periods depending on the degree of stress detected (Chehab et al., 2008;Chen et al., 2005;Karban and Baldwin, 1997). Plants respond to stress by producing phytohormones and volatile terpene compounds (VTCs) and by triggering defence-associated genes (Chehab et al., 2009;Green and Ryan, 1972), which can result in development deceleration, leaf deterioration and possible organ detachment (Jaffe and Biro, 1979). It has been found that shaking cocklebur plants causes a surge in leaf senescence (Salisbury, 1963) and that placing seedlings on a shaker table causes phloem to proliferate (Berlyn lab, unpublished). Other research has shown that plants respond to mechanical stimuli through chlorophyll content modi cation and stomata closure, which leads to senescence and abscission (Biddington, 1986).
Tree survival depends on the chemistry of phenolic compounds, which are a class of chemicals characterised by a hydroxylated benzene ring (Smith, 1997). In trees, phenolics are present as polymers, acids or glycosylated esters (Harbome, 1979) and perform diverse roles. Phenolic compounds or polyphenols are one of the most widespread class of compounds in plant ecology, and there are more than 8,000 known phenolic structures (Tsao, 2010). These phenolics exists in almost all plant organs and have myriad functions based on their structure; they act as skeletal components of different tissues and as pigments in a variety of plant organs (Ignat et al., 2011). Polyphenols are secondary metabolites that are essential for plant development and propagation (Tanase et al., 2019). Phenolic acids are present in the combined soluble form conjugated with sugars or organic acids and comprise elements of composite structures, such as lignins and hydrolyzable tannins (Tomás- Barberán and Clifford, 2000).
Phenolics are esteri ed with sugar moieties or are equally puri ed in the entire plants; most are present in cell walls or stored in vacuoles (Smith, 1997). Disruption to cells caused by environmental stress or laboratory tissue emulsi cation can generate phenolic compounds, which separate enzymatically from their ester bonds and quickly alter cell components, such as enzymes and proteins (Chalker-Scott and Fuchigami, 1989). Any form of mechanical damage is likely to intensify phenolic synthesis (Thorp and Hall, 1984;de Jaegher et al., 1985;van Loon and Gerritsen, 1986) and accumulation (Baldwin and Schultz, 1983;Barker and Peterson, 1984;Kimmerer, 1988), particularly in cell walls (Berlyn and Mark, 1965;de Jaegher et al., 1985;Biggs, 1986;Rickard and Gahan, 1983;Biddington, 1985). Phenolics are functional compounds in plants, acting as a stress-defensive mechanism and attracting or defending against herbivores and plant pathogens (Treutter, 2005). Phenolics are widely distributed in plants, including in the roots, shoots, woody tissues, leaves, phloem, owers and leaf buds, pollen and styles (Misirli et al., 1995).
Plants play an essential role in the biogeochemical sequences of carbon and water and, therefore, are an important element affecting the Earth's climate (Carslaw et al., 2010). Further, plants continually release responsive biogenic volatile organic compounds to the atmosphere, where they contribute to atmospheric gas-phase chemistry and particle construction (Mentel et al., 2013). Plants are the main source of volatile organic compound emissions globally (Guenther et al., 2012). Once released into the atmosphere, plant volatiles undergo oxidative processes that produce low-volatility vapours and biogenic secondary organic aerosol (Riccobono et al., 2014;Tröstl et al., 2016). Atmospheric aerosols affect the climate by dispersing and absorbing radiation and by contributing to the development of clouds (IPCC, 2013;Pajunoja et al., 2015). This paper aims to examine the ongoing and interconnected relationship between forests and wind, which is integral to internal and external communication, cloud formation and precipitation.

Materials And Methods
The last-standing forest in Hourieland is located in the Nehle Valley north of the ancient town of Akra, between Hasya Qalotk in the Pïris Range and Seré Akra Range (current Kurdistan; Figure 01). The majority of trees in the forest are Berï (Oak; quercus) and related species, including the common Berï that produces acorns; the Mazi that produces berries the size of hazelnuts, which are used for beer and medicine; Gordïl (Dyer's oak; Quercus lusitanica); and Mask, which produces legume-rich leaves and mango-sized loofah. Less common trees in the same forest include the Pistachio (pistacia); the Bink, which produces legumerich leaves and medicine; the Dindar (the rare Hurrian Dindar medicinal berry tree); the Kavot (the rare Hurrian medicinal berry tree); the Kezan (pistacia atlantica), which produces hard shell wild pistachios; and the Banoshk, which produces soft shell wild pistachios. Most of these trees are evergreen. Evergreen, leathery-leaved shrubs and trees characterise temperate forests in much of the southern hemisphere, as well as Mediterranean scrub, slightly wetter sclerophyll forests, and even wetter temperate rain forests in areas of winter rainfall on the west sides of the continents at mid-latitude. Evergreen, needle-leaved conifers dominate many boreal forests at high latitudes in the northern hemisphere (Small, 1972;Givinish, 2002). Chabot and Hicks (1982) argued that frequent frosts favoured vessel-less (and, perhaps coincidently, evergreen) conifers at high latitudes and altitudes. These trees shed their leaves in spring during and after leaf growth (Nitta and Ohsawa, 1997), though most species keep two or more cohorts of old leaves in the early mid-spring (Suehiro and Kameyama, 1992). The conditions are comparable to sclerophylls in the Mediterranean Basin, which shed their leaves mainly in spring (Escudero et al., 1992;Rapp, 1969;Montserrat-Martí and Pérez-Rontomé, 2002), although the leaves of some species constantly regenerate to compensate for old, damaged leaves and those consumed by herbivores. This area was the subject of a 10-year study conducted by the author of the present study. While the oak tree family is ubiquitous in Hourieland, the rare dindar, bink, kavot, kazan and banoshk species only grow in upper valleys that are adapted to heavy snow cover, and all are endangered. The author, always accompanied by the elder Dad Kadan and several of his trusted relatives, quanti ed the lost forest and measured the sumac farms. The area was also calculated through visual observation of the two peaks at the Hasya Qalotka Range and the two peaks at the Deré Kadana Range. A Panasonic camcorder AG-HPX500, Nikon D5600 SLR camera and mobile phones were used to lm the burnt and cleared areas. Using the rope method, the Waré Mirdavia forest was calculated at approximately 10 Km^2, as shown in Figure 03. For each clearing, the USGS map was marked with the yellow coloured lot measuring 2500 m^2 by the author and the crew, and for each sumac farm, a rust coloured lot was added for every 2500 m^2. The green lots indicated what was left of the forest. Each 1 K^2 consisted of 400 lots. As the upper valley area measured approximately 10 x 1 〖 Km〗^2, there were a total of 4,000 lots.
As proper weather balloons were not available in Hourieland, a cluster of small balloons lled with helium and tted in polyester fabric was utilised ( Figure 04). The balloons were secured to a tree trunk in the upper valley with a 1 km main thick rope. Every 100 m, a 25 m single-coloured fabric strip was attached to the main rope to visually gauge the direction and speed of the wind. A second auxiliary 1 km thick rope was used to transport equipment to the upper sphere. A third 2 k+ m thinner rope was passed through a ring at the base of the weather balloon and was subsequently passed through two more rings enclosing the auxiliary transport rope. The base of an empty one-litre aluminium bottle was secured to the end of the 2 k+m third rope ( Figure 05A and B). Water was boiled in a deep pan, and the aluminium bottle was immersed until it lled up and reached the temperature of the water. The aluminium bottle was lifted out of the pan, and a cork with four horizontal channels on its side was placed against the bottle's ori ce. The bottle was turned upside down to allow the hot water to pour out. The bottle was immediately secured with the cork to insulate it from the air. The pressure inside the bottle pulled the cork into the bottle's neck quickly so that the bottle became airless. A fourth 1 km thin rope was secured through the middle of the cork. A U-shaped steel bar with a hole for the cork's rope to pass through and a spring secured against the cork's top was tightened to the bottle's neck by a steel ring fastener ( Figure 05A and B). During high winds that shook the trees and uttered their leaves, the aluminium bottle was lifted 50 m above ground. The third and fourth thin ropes were pulled down at the same time that the cork was pulled out of the bottle's neck, which allowed the phenolic saturated air to ll the bottle through the four horizontal channels on the side of the cork. Once the third and fourth ropes were loosened, the steel spring pushed the cork back up the bottle's neck, securing the phenolics in the aluminium bottle. This bottle was then lowered to the ground, and its contents were tested using an olfactometer. The process was repeated, and the airless aluminium bottle was sent up to 50 m above the previous collection position until the last reading was collected at the base of the weather balloon. Wind speed was also measured using a portable anemometer. As it was cumbersome to send the anemometer up using the balloon ropes, one of Dad Kadan's relatives climbed up the peaks of the Hasya Qalotka and Deré Kadana ranges each time the phenolics were counted in the day or night during late autumn.
Deforestation can occur when populations increase, cash cropping escalates or when power tools are used for clearing and cultivating (Vanclay, 1993). In the present study, the constant deforestation of both the lower and upper valleys caused snow cover to decline.

Results
The irresponsible clearing without replacing the steep surfaces with the sumac weed, decimated the forest in the upper valley (Table 01 Fish farms were decimated. The available water from the severely downgraded Zéwa Gulley waterfalls became strictly rationed, causing angst and disputes. While more than ve readings were conducted in measuring snow depth intermittently, (Table 02) shows the decline in snow cover over the 10 year period of the study at both the lower and upper valleys. With less snow cover days spring season would logically yield less water discharge to downstream areas, as well as gradual increase in temperature, particularly in summer when water was needed most. The extreme decline in snow precipitation maybe caused by the extreme decline in forest cover. On closer inspection at tree level, the portable olfactometer registered the presence of phenolics by all the trees in the forest. To determine the quantity of phenolic compounds in the oak, dye oak, mazi, mask, pistachio, bink, dindar, kavot, kazan and banoshk, the author took 10 x 100 g samples from each tree. The samples were separately mixed with 250 g combination of methanol (CH OH)/acetone ([CH3]2CO)/water (H2O), boiled in a kettle each at 80-90° C. The author obtained total phenols from the ten tree species.
The result of the 100 g samples taken from the 10 trees after separately mixed with 250 g mixture of methanol (CH OH)/acetone ([CH3]2CO)/water (H2O), boiled in a kettle each at 80-90° C came as follows: To state total phenols in a sample of 100 g of the oak tree the author performed the extraction, added FC reagent and read the absorbance at 753 and its curve resulted 0. Data were obtained from plants on the ground. However, due to the heat generated by the uttering of leaves, the phenolics collected using the aluminium bottle from the atmosphere between 800 m and 2,000 m above sea level showed a higher percentage, and quanti cation varied from 1,000-2,000 µ from 2009-2016. The quanti cation later decreased to 200-300 µ in 2017 and decreased again in 2018 (Table 03). The lake of phenolics changed constantly according to the intensity of the wind and the amount of time that the leaves uttered. Therefore, the more live tree leaves, the more leaves that uttered and the more phenolics were discharged above the forest.

Discussion
Trees endure signi cant wind forces and usually survive with little or no wounding (James and Haritos, 2014). The dynamic responses of trees have been studied using multifaceted prototypes and multi-model approaches that specify the morphology of trees and the dynamic interfaces of branches, which can affect the damping reaction in winds (Rodriguez et al., 2008). The damping reaction has the important effect of causing tree leaves to utter and subsequently, friction and heat. When an object moves along a surface or through a viscous liquid or gas, the force resisting its motion is referred to as 'friction'.
Frictional forces are nonconservative and convert the kinetic energy of a material in sliding contact to internal energy (Krim, 2012). Fluctuations of particles have the same origin as dissipative frictional forces in which one force (wind) performs work against another (wind) that tries to shift a system in a particular direction (Einstein, 1906;Krim, 2012). If the two mica surfaces of a single leaf are made to slide relative to each other with a molecularly thin lm between them (i.e., molecules between the upper and underside of a leaf; Figure 07), a viscous friction form is expected to occur for liquid-like behaviour, assuming that the shear occurs in the lm and not at the mica-liquid boundary (Klein andKumacheva, 1995-1998;Docherty and Cummings, 2010;Mate and Marchon, 2000). Even without acknowledging wind-affected movement, the wind has an important effect on the thermal condition of plants (Schuepp, 1972;Vogel, 2009) and in gaseous interactions and transference (Grace, 1978;Defraeye et al., 2012). In the presence of a gradient of gas concentration, molecular agitation is responsible for the transfer of mass, which is generally referred to as 'diffusion', although this word can also be applied to momentum and heat (Monteith and Unsworth, 2013). Based on the notion that the signi cance of leaf design lies in hydraulic and thermal management (Nicotra et al., 2011), Rupp and Petra (2019) proposed the theory of leaves as heat and mass exchange biostructures. The leaf surface heat transfer coe cient increases with increasing wind speed and decreases as the measuring position moves along the wind direction from the leading edge (Jürges, 1924;Yoshida et al., 2012;Asawa et al., 2016;Kinoshita and Yoshida, 2017). The effect of wind on the movement of the leaves of trees is crucial for biological purposes (e.g., photosynthesis, pathogen development and herbivory) and also has indirect in uences, such as on witransmission or animal communication (Tadrist et al., 2018).
Leaf uttering has various effects on vital biological plant processes. For example, leaf uttering can reduce insect herbivory (Yamazaki, 2011) and enhance heat exchange (Schuepp, 1972;Grace, 1978), gas trade (Nikora, 2010) and photosynthesis (Roden and Pearcy, 1993;Roden, 2003). The uttering of leaves may also be important in decreasing the water content of leaves and disposing of pathogens in water droplets. Tree foliage may interrelate by shaking, touching, leaf-to-leaf rubbing or by closing into bundles (Vogel, 1989), assuming that all foliage is the same except for their position in relation to photosynthesis (Pearcy, 1990;Rascher and Nadbal, 2006).
In line with optimisation theory, stomatal aperture varies over time to mitigate water loss for the required amount of carbon gain (Cowan, 1977). For example, there is no carbon gain in plants at night as the stomata shut due to the absence of photosynthetically active radiation, which is essential for the light reaction of photosynthesis. However, the fractional shutting of the stomata of some trees at night may present an ecological advantage. Under these conditions, fractional stomatal shutting can be encouraged by enabling trees to continue photosynthesis until evening and improving photosynthetic e ciency earlier in the morning than competitors (Daley and Phillips, 2006). However, wind can close stomata (Kozlowski, 1979). In the present study, trees were found to open their stomata at night, not due to the presence of light, but because they were violently shaken by the wind (Figure 07). When strong winds pass through a tree, uttering the leaves rapidly, heat is generated from the accelerated movement. The mechanically heated tree responds by sending phenolic compounds to the stomata to defend itself from 'attack' by a herbivore, when the wind is responsible for the assault. At higher than usual temperatures at night or daytime, phenolic compounds saturate the guards surrounding the stomata gates, mostly at the lower side of the leaves, which forces the stomata to swell and open and enables the accumulated phenolic compounds to escape through the gates and attack the predator. The wind then carries the escaped lightweight phenolic compounds into the air. Aerosols are solid or liquid particles that are su ciently small to remain suspended in the atmosphere for long periods (Monteith and Unsworth, 2013). The phenolic compound particles subsequently collide with incoming or stationary cloud particles, which causes them to become heavier and form snow, which descends to the ground due to gravity. Slight (i.e., ~100 m) differentials in topography and vegetation considerably change the near-surface ow eld through mechanical means, such as ow parting around obstructions, improved turbulence from ampli ed surface coarseness, and speeding-up over elevations and thermally driven ows stimulated by local variant ground heating in montane areas (Defant, 1949;Banta, 1984;Banta and Cotton, 1982;Whiteman, 2000;Zardi and Whiteman, 2013;Chrust et al., 2013). The rst indications of imminent precipitation are low surface, chaotic and violent winds that shake the trees and oating clouds of dust that accumulate on leaves, followed by a cleansing process. The end of this period is called a 'perfume front', whereby wind violently shakes the trees, uttering their leaves, triggering stress mechanism responses, generating heat and stimulating the fresh and clean leaves to release phenolic substances ( Figure 08). Mechanical stress as a consequence of shaking and bundling has been shown to prompt the biosynthesis and adaptation of ethylene and VTCs in balsam r trees (Korankye et al., 2018).
The signalling mechanism between the wind and forests, which is the natural seeding of clouds, was observed by the author over 10 years and for numerous generations by Hurrian elders and their ancestors ( Figure 08). In 1991, during the rst Gulf War, the soot from burning oil elds in Kuwait precipitated over Hourieland. The falling soot was given the name 'black rain' and also fell as black snow on the mountains. Clouds may have formed from nearby open waters, including the Mosul Dam, and the Hurrian forests. However, the presence of large amounts of seeding soot in the clouds suggests that the clouds may have travelled over 1,000 km from the southern Gulf north towards Hourieland, covering the mountains and the phenolic lakes in Hourieland, where cloud precipitation then occurred.
The olfactometer reading of the space above the forest recorded a higher quantity of phenolics than the usual forest sphere. While the usual forest sphere phenolics hovered around 200-300 -m^3 at 5°C and 500 -m^3 at 15°C, 50 m above the tree line, the olfactometer registered around 1000-2000 -m^3 ( Figure  09). The measurements were taken at several elevations from the valley below up to the mountain ridge. A weather balloon 1,000 m above the ground was used for the upper valley of Waré Mirdavia. Snow often precipitated at night and continued the next day or for many days or months depending on the topography, size and density of the lake of phenolics. The lake of phenolics is as large, dense and quanti ably high as the number of trees on the ground. The more forested an area, the more precipitation occurred.  (Ramankutty and Foley, 1999). Deforestation has considerable and pervasive adverse effects on climate, hydrology, soil and biodiversity and also affects humans and the economy (Meyfroidt and Lambin, 2011). Large swathes of native forests have been destroyed to produce resources. In their limited and reduced condition, the remaining native forests face the possibility of the rapid and severe stress of climate change and ampli ed climate variability (Dale et al., 2001). The mountain cryosphere of snow, ice and permafrost plays an important role in these ecosystems and is a crucial source of water for downstream regions (Huss et al., 2017). Multifaceted interactions between cloud cover, solid and liquid precipitation, surface albedo and net radiation contribute to further degradations in glacier mass balance and snow-covered topographies (Painter et al., 2012). As a result, glacierised mountains are threatened by conditions that lead to declines in snow and ice cover (Huss et al., 2017). Ellison et al. (2017) argued for the need to reverse the pattern of deforestation, explaining the cooling and hydrologic effects of forests on the earth. Their ndings are in line with new research that suggests that forests act as 'biotic pumps', 'generators' or 'recyclers' to regulate the surrounding water balance (Makarieva et al., 2006;Makarieva and Gorshkov, 2007;Sheil and Murdiyarso, 2009;Ellison et al., 2012;Sheil, 2014). A concerted effort to promote forestation, therefore, is needed to counter the catastrophic effects of global warming and preserve living standards.

Conclusion
Wind is a quintessential element in its relay with forests, clouds and their topography. Numerous studies established that forests have a de nite impact on precipitation, so as the topography of the targeted region, in this instance a seldom researched area called Hourieland. In this poorly managed area the last forest was cleared to plant the poor yielding sumac shrub, without utilizing most of the cleared land. It resulted in extreme decline in snow cover, and even drought. The study of this locality observed the various wind speeds, levels and directions, which set the ecology of the montane orography, where surface fog and spherical clouds interacted with the trees to dust, wet, and cleanse the forest. The wind exerted force against the trees, uttering their leaves, causing them to heat up, prompting the trees' external and internal signaling mechanisms to react, emitting phenolic compounds. These light weight aerosols formed a lake above the forest. The wind also generated and transported clouds from nearby and distant open waters. The cloud particles collided with the lake of phenolic compounds above the forest resulting in precipitation. Large scale deforestation resulted in less or not enough phenolics to form a lake of phenolics above the forest location, resulting in less aerosol and cloud particle reaction, and less precipitation of snow cover. The author acknowledges the immense contribution and dedication of Dad Kadan, elder of the village of Ba-Mij-Mij for his long term Hurrian hospitality, guidance, protection, support and ora and fauna knowledge.
Funding "The research did not receive funding from any entity other than the author" Availability of data and material "All data are within the manuscript" Code availability (N/A) Funding (N/A) Con icts of interest/Competing interests (include appropriate disclosures) "The author declares that they have no con ict of interest/competing interests." Ethics approval (N/A) Consent to participate "The author consents to participate in whatever the journal endeavors to do with the manuscript" Consent for publication "The author consents for the journal to publish the manuscript and its data as it sees t." Availability of data and material "All data included" Code availability (N/A) Authors' contributions "The author is the sole authority for this manuscript and all its contents."

Key Message
Forests produce abundance of phenolic compounds which condense clouds particles, forming ice particles and resulting in precipitation. Year