Макарова, О. А. Фенологический атлас растений / Н. В. Поликарпова, О. А. Макарова ; М-во природ. ресурсов и экологии Рос. Федерации, Федер. гос. бюджет. учреждение «Гос. природ. заповедник «Пасвик» ; [худож.: Хохлов В. А. ; пер.: Кислова О. С.]. - Рязань : Голос губернии, 2016.

22Д A phenological atlas of plants Senescence in such plants is quite gradual. The end of leaf fall date is defined as the day on which the crown of a tree or shrub became completely leafless. Minor amounts of leaves sometimes retained on the top of the crown can be ignored. The inside of the crown in pine has shed yellow needles and the crown is green again, but appearing sparser. Needle drop in spruce is observed starting October-November and may take quite a while. The fallen needles are distinctly visible on the snow cover, especially after windy days. Further info Fenolog .rgo.ru : End of leaffa ll (needle fa ll) is recorded on the day when nearly all the monitored specimens of a species are completely free of leaves (needles). Occasional dry leaves on shoots are disregarded, just like single plant specimens with delayed end of leaf fall. After heavy autumn frost (-3 - -5°C), leaf fall would be very intensive, sometimes taking just a few hours (in alder, pine). On windy days leaf fall should be monitored more frequently not to miss its end. If frost happens early, the leaves of some plant species turn brown and stay on through the winter. This situation should also be properly recorded. In late autumn, after leaf fall had ended, woody species go to true dormancy. In this period, the plants w ill not resume growth even if the environmental conditions are favorable, such as during winter thaw. It would however be wrong to think that all life within a plant comes to a halt in this period. There are complex biochemical processes underway to prepare the plant for the next growing season. Late in winter, the phase o f relative or enforced dormancy replaces the true dormancy phase long before bud break. This condition in plants means they are prepared to start vegetative development as soon as external factors permit. Terentjeva £ Yu. (2008): End of leaffa ll is recorded on the day when all leaves had fallen or only dry leaves remain on a plant. In trees and shrubs producing two or more generations of leaves per season autumn leaf senescence happens with a time lag. In winter annual trees and shrubs, older leaves seasonally die back every year. Complete senescence - a leaf has fully changed color, wilted, dried up.