دراسة الأحداث البيولوجية: الفرق بين النسختين

 

'''Phenology''' is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation). The word is derived from the [[Greek language|Greek]] φαίνω (''phainō''), "to show, to bring to light, make to appear"<ref>[http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dfai%2Fnw φαίνω], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref> + λόγος (''[[logos]]''), amongst others "study, discourse, reasoning"<ref>[http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dlo%2Fgos λόγος], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref> and indicates that phenology has been principally concerned with the dates of first occurrence of biological events in their annual cycle. Examples include the date of emergence of leaves and flowers, the first flight of butterflies and the first appearance of [[bird migration|migratory]] birds, the date of leaf colouring and fall in deciduous trees, the dates of egg-laying of birds and amphibia, or the timing of the developmental cycles of [[temperate]]-zone [[honeybee|honey bee]] colonies. In the scientific literature on [[ecology]], the term is used more generally to indicate the time frame for any seasonal biological phenomena, including the dates of last appearance (e.g., the seasonal phenology of a species may be from April through September).

The concept of [[Growing-degree day]] contributes to our understanding of phenology.

 

Observations of phenological events have provided indications of the progress of the natural calendar since ancient agricultural times. Many cultures have traditional phenological proverbs and sayings which indicate a time for action: "When the sloe tree is white as a sheet, sow your barley whether it be dry or wet" or attempt to forecast future climate: "If oak's before ash, you're in for a splash. If ash before oak, you're in for a soak". But the indications can be pretty unreliable, as an alternative version of the rhyme shows: "If the oak is out before the [[Fraxinus excelsior|ash]], 'Twill be a summer of wet and splash; If the ash is out before the oak,'Twill be a summer of fire and smoke." Theoretically, though, these are not mutually exclusive, as one forecasts immediate conditions and one forecasts future conditions.

 

In Japan and China the time of blossoming of cherry and peach trees is associated with ancient festivals and some of these dates can be traced back to the eighth century. Such historical records may, in principle, be capable of providing estimates of climate at dates before instrumental records became available. For example, records of the harvest dates of the [[pinot noir]] [[grape]] in [[Burgundy (region)|Burgundy]] have been used in an attempt to reconstruct spring–summer temperatures from 1370 to 2003;<ref name=Chuine>{{cite journal | last1 = Chuine | first1 = I. | last2 = Yiou | first2 = P. | last3 = Viovy | first3 = N. | last4 = Seguin | first4 = B. | last5 = Daux | first5 = V. | last6 = Le Roy | first6 = Ladurie | year = 2004 | title = Grape ripening as a past climate indicator | url = http://www.cefe.cnrs.fr/fe/pdf/2004_Nature_432_289_290.pdf | format = PDF | journal = Nature | volume = 432 | issue = 7015| pages = 289–290 | doi = 10.1038/432289a | pmid = 15549085 |bibcode = 2004Natur.432..289C }}</ref><ref name=Keenan2007>{{cite journal | last1 = Keenan | first1 = D.J. | year = 2007 | title = Grape harvest dates are poor indicators of summer warmth | url = http://www.informath.org/pubs/TAC06a.pdf | format = PDF | journal = Theoretical and Applied Climatology | volume = 87 | issue = | pages = 255–256 | doi = 10.1007/s00704-006-0197-9 |bibcode = 2007ThApC..87..255K }}</ref> the reconstructed values during 1787–2000 have a correlation with Paris instrumental data of about 0.75.

 

[[Robert Marsham]] is the founding father of modern phenological recording. Marsham was a wealthy landowner who kept systematic records of "Indications of spring" on his estate at [[Stratton Strawless]], [[Norfolk]], from 1736. These were in the form of dates of the first occurrence of events such as flowering, bud burst, emergence or flight of an insect. Consistent records of the same events or "phenophases" were maintained by generations of the same family over unprecedentedly long periods of time, eventually ending with the death of Mary Marsham in 1958, so that trends can be observed and related to long-term climate records. The data show significant variation in dates which broadly correspond with warm and cold years. Between 1850 and 1950 a long-term trend of gradual climate warming is observable, and during this same period the Marsham record of oak leafing dates tended to become earlier.<ref name="Sparks & Carey">{{cite journal | last1 = Sparks | first1 = T.H. | last2 = Carey | first2 = P.D. | year = 1995 | title = The responses of species to climate over two centuries: an analysis of the Marsham phenological record, 1736-1947 | url = | journal = Journal of Ecology | volume = 83 | issue = 2| pages = 321–329 | doi = 10.2307/2261570 }}</ref>

 

However, these phenological parameters are only an approximation of the true biological growth stages. This is mainly due to the limitation of current space based remote sensing, especially the spatial resolution, and the nature of vegetation index. A pixel in an image does not contain a pure target (like a tree, a shrub, etc.) but contains a mixture of whatever intersected the sensor's field of view.

 

* [[Citizen science]]

* [[Nature Detectives]]

* [[Biological life cycle]]

 

 

* [http://www.pwrc.usgs.gov/bpp/ North American Bird Phenology Program] Citizen science program to digitize bird phenology records

* [http://neoninc.org/budburst/ Project Budburst] Citizen Science for Plant Phenology in the USA