**2. Phenology**

In general, Phenology is the observation and measurement of events in time [2]. Obviously, the word phenology is composed of the part "pheno" which refers to phenomena and "logy" which is commonly known to mean science or study, thus phenology is literally the study or science of phenomena. Practically, Phenology refers to the study the cyclic phenomena of living beings mainly plants and animals including insect and their succession in seasons as well as their timings [1, 3]. This is under the direct influence and control of climate and surrounding environmental conditions including the duration of sunlight, precipitation, temperature and other life-controlling factors [1]. The recent climate changes makes the deep mastery and comprehension of phenology worthwhile, because some unpredicted climate changes could cause many crop damages. Actually, the assessment of impacts of projected climate changes on natural ecosystems is not based on accurate scientific modeling or field studies at regional level [1], and It is well documented that plant and animal phenology is changing in response to recent climate warming in the Palearctic [3]; besides, global change, encompassing natural and anthropogenic changes to the Earth system at sub-annual to geologic time scales, has strong interactions with vegetation phenology [4]. Thus phenology is central and crucial as a background for the discipline of agronomy and mainly agro-meteorology to predict the eventual response of living being to the unpredictable climate changes and therefore probable agricultural damages.

The term of phenology was first introduced in 1853 by the Belgian botanist Charles Morren. It refers to the science that measures the timing of life cycle events for plants, animals, and microbes, and detects how the environment influences the timing of those events. Namely, it focuses on how environmental factors mainly climatic variables influence the phenol-phases to hence make a harmony between seasons and life cycle events including defoliation, plant dormancy, leaf budburst,

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bodies of living beings.

*Climate as the Major Factor Controlling Phenology DOI: http://dx.doi.org/10.5772/intechopen.95893*

and precipitation affect its timing [2].

**3. Climate and weather**

place in due season [6].

in many regions.

**4. Climate elements controlling phenology**

the elaboration of the discipline of bioclimatology.

blooming and first flower, last flower, first ripe fruit, and leaf shedding, and for animals this includes molting, mating, egg-laying or birthing, fledging, emergence from hibernation, and migration. Thus, phenologists record the dates when every event occurs, its duration and how environmental conditions such as temperature

The timing of phenological events can be quite sensitive to environmental conditions mainly climatic [2, 4, 5]. For example, an advance of leaf budburst and blooming for could be caused by warming an drought in spring and this could be for two weeks earlier than usual, whereas cold and moisture could exceptionally could equally delay them. Thus, weather and climate controls the timing of phenol-phases which vary among years [2]. Effectively, climate cyclic variations are the controlling variables of phenol-phases timing. In plants, bud-burst, leaf-expansion, abscission, flowering, fertilization, seedset, fruiting, seed dispersal and germination all take

On the one hand weather is limited to a very short period of time from one day to less than week and it includes atmospheric conditions of a region, such as temperature, precipitation, humidity, wind, and sunshine. The climate of a region, on the other hand, concern a long period more than thirty years commonly defined as the conventional period for climatic studies. Climate consists of the generally-prevailing weather conditions for this period and in a large geographic region. For example, Santa Barbara, California is characterized by a Mediterranean climate – warm, dry summers and cool, moist winters. There are, however, daily and weekly changes in the weather that can rapidly change the temperature, sunshine, and wind conditions [2]. Nonetheless, there is no steady rhythm for all years particularly in the context of recent climate changes. This would not be tolerated by some species and therefore they are likely been extinguished and rarified

Temperature, solar radiation, and water availability are assumed to be the key factors that control plant phenology [4]. However, not only these climatic factors. Indeed, temperature is an inevitable factor on which depends all the chemical reaction and mainly those occurring inside cells of living organism. In addition the temperature is both a characteristic of live and an indispensable condition to survive. Some biological functions and reaction may be inhibited or stopped by cold like in hibernation and dormancy. The solar radiation is unequivocally source of energy which is transformed from it luminous form to the chemical form (ATP) by the photosynthesis in the chlorophyll within plants. Furthermore, sun light is factor to fixate the calcium, to product vitamin and the duration of insolation which is called photoperiod determines the season of fall, season of bud bursting and blooming. Precipitations are source of water for crops. Water is indispensable for any form of life on earth. Indeed water is the solvent in all physiological solution in living organisms. As well as it transmits nutrients and regulates temperature of

In fact all the climate with its elements and their features including duration, frequency and intensity are influencing phenophases and living beings lives whence blooming and first flower, last flower, first ripe fruit, and leaf shedding, and for animals this includes molting, mating, egg-laying or birthing, fledging, emergence from hibernation, and migration. Thus, phenologists record the dates when every event occurs, its duration and how environmental conditions such as temperature and precipitation affect its timing [2].
